Yahtzee: end-of-game stats dialog compared with previous games

Co-Authored-By: Claude Sonnet 5.5 <[email protected]>
Claude-Session: https://claude.ai/code/session_0177JQTtqM7EzJyXYiZYEJTX

CLAUDE.md

@@ -1,78 +1,61 @@
-> **Moved to Gitea.** CI now runs on Gitea Actions at
-> `git.wallacenet.ca/devadmin/ProLibertateGames`, publishing to Cloudflare Pages
-> (`plg.wallacenet.ca`) only. The sandbox notes below describe the earlier GitHub
-> setup (no CI run from session pushes, `workflow_dispatch` as the workaround);
-> re-verify them against Gitea before relying on them.
-
 # Working on this repo with Claude
 
-## Nothing a session does triggers CI. Dispatch it explicitly.
+CI runs on **Gitea Actions** at `git.wallacenet.ca/devadmin/ProLibertateGames`
+(workflows in `.github/workflows/`), publishing to Cloudflare Pages
+(`plg.wallacenet.ca`). The workflow below was measured on the dev machine
+(`~/ProLibertateGames`); it replaces the earlier GitHub-sandbox notes, which no
+longer apply.
 
-GitHub creates **no workflow run** for anything this sandbox does — pushing a
-branch, opening a pull request, or merging one. All of it goes through the same
-integration, and GitHub suppresses event-triggered runs from it. The pull
-request will say it was opened by the repo owner; that is only how the UI
-attributes it, and it does not change the suppression.
+## Build, test and lint locally
 
-This was measured, not assumed:
+Gradle works on the dev machine. Two environment variables are required: the
+default JDK is 25, which Gradle 8.14 cannot use, and the Android SDK lives in the
+home directory.
 
-| Action | Result |
-| --- | --- |
-| Human pushes a Claude-authored commit (`d165e5ef`, `469c900e`) | CI runs |
-| Session pushes `dev` / `main` (`43394b8`, `742add4`) | no run |
-| Session opens a PR against `dev` (#1) | no run |
-| Session calls `workflow_dispatch` | **runs** |
+```
+export JAVA_HOME=/usr/lib/jvm/java-17-openjdk-amd64
+export ANDROID_HOME=$HOME/android-sdk      # platform 34, build-tools 34.0.0
+./gradlew testDebugUnitTest lintDebug assembleDebug
+```
 
-`workflow_dispatch` works because it creates a run directly instead of relying
-on an event. It is the only mechanism available from a session, so every build
-has to be asked for by hand.
+The Katan tests run in seconds; a clean build takes a few minutes. Run the full
+suite, lint and `assembleDebug` before pushing: they are what CI runs. There is
+no KVM, so no emulator; the engine and the UI logic are covered by unit tests
+(see `docs/UI-catan.md`).
 
-## Verify before merging, without publishing
+## Shipping: branch, PR, CI, merge
 
-`ci.yml` builds, tests and lints on any ref, but its staging and publishing
-steps are gated on `github.ref == 'refs/heads/dev'`. Dispatching it on a
-**feature branch** therefore gives the full check — build, unit tests, Android
-lint — and publishes nothing.
-
-So the working loop is:
-
-1. Commit and push the feature branch.
-2. Dispatch `ci.yml` on that branch. Wait for green. This is the real review
-   gate, and it is the only verification that exists (see below).
-3. Open the PR through the API and merge it there, so the change is reviewable
-   and the merge commit is honest about what happened. Neither step builds
-   anything.
-4. Dispatch the target branch's workflow to actually build and publish:
-   `ci.yml` on `dev`, `release.yml` on `main`.
-
-Skipping step 4 leaves a branch whose head was never built and no release.
+1. Branch from `dev`; before pushing, merge `origin/dev` in (it moves between
+   sessions).
+2. Plain `git push` has no credentials. Use the Gitea token as a one-off header:
+   `git -c "http.extraheader=Authorization: token $(cat ~/.config/gitea/token)" push -u origin <branch>`.
+3. Open the PR with `POST /api/v1/repos/devadmin/ProLibertateGames/pulls`
+   (same token, `Authorization: token ...`). CI (`ci.yml`) runs on the PR: build,
+   unit tests and Android lint; it publishes nothing. Poll
+   `/actions/runs` until it completes (about 7 minutes).
+4. Merge with `POST .../pulls/N/merge {"Do":"merge"}`. The push to `dev` runs
+   `ci.yml` again and publishes the build (about 9 minutes).
 
 ## Merging is a shipping action
 
 Both long-lived branches publish, so a merge is a release, not just an
 integration:
 
-- **`dev`** → `ci.yml` publishes a `v<series>.N-dev` **prerelease**, offered by the
-  in-app updater to anyone on the Dev channel.
-- **`main`** → `release.yml` publishes a **production** release, which the
-  updater installs for everyone on the Production channel.
+- **`dev`** publishes a `v<series>.N-dev` build to
+  `https://plg.wallacenet.ca/dev/latest.json`, offered by the in-app updater to
+  anyone on the Dev channel.
+- **`main`** runs `release.yml` and publishes a **production** release for
+  everyone on the Production channel. Confirm before merging to `main`.
+  `release.yml` runs `assembleDebug` only (no tests, no lint), so a `main`
+  release is only as verified as the `dev` build it replays.
 
-Confirm before shipping to `main`. Note that `release.yml` runs `assembleDebug`
-only — no tests, no lint — so a `main` release is only as verified as the `dev`
-build it replays.
+## Katan
 
-## Gradle does not run in the sandbox
-
-`./gradlew` cannot resolve the Android plugin here: the proxy blocks
-`dl.google.com` with a 403. No local build, no local test run, no local lint. A
-dispatched CI run is the only way to find out whether a change compiles.
-
-## A permanent fix, if you want one
-
-The suppression is a property of the sandbox's credential, so it cannot be
-fixed from inside a session. Giving the environment a personal access token to
-push with would make pushes and PRs behave normally for everyone. Until then,
-the dispatch step above is the workaround.
+The island game is catalogue id `catan`, shown as **Katan**. It has two rule
+sets chosen at setup: the base game (`docs/RULES-catan.md`) and Cities & Knights
+(`docs/RULES-catan-ck.md`, code in `game/catan/CatanCk*.kt`, state behind
+`CatanState.ck`, which is null in the base game). The screen is layered; see
+`docs/UI-catan.md` before changing it.
 
 ## Bash output is filtered before it reaches the model
 

README.md

@@ -373,7 +373,9 @@ game:
   the game is out of print and the rulebook could not be obtained, so the
   document says which parts are attested and which were derived
 - [Katan](docs/RULES-catan.md) — the island game (catalogue id `catan`); the
-  rules engine and AI are in place, the screen lands with its own task
+  rules engine, AI and screen are in place
+- [Katan: Cities & Knights](docs/RULES-catan-ck.md) — the expansion rule set, chosen on
+  the setup screen: commodities, knights, barbarians, city improvements and progress cards
 
 ## Layout
 
@@ -396,7 +398,7 @@ game/          rules engines and AI — pure Kotlin, no Android, unit-tested
   mastermind/  Mastermind codes, scoring, and a code breaker
   pirates/     Pirates and Bulgars — the cross board, the hunt, search
   tayu/        Ta Yü tile geometry, river rules, scoring, AI
-  catan/       Katan island geometry, production, trade, dev cards, heuristic AI
+  catan/       Katan island geometry, production, trade, dev cards, Cities & Knights, heuristic AI
 net/           wire protocol, LAN transport, lobby, match driver
 score/         scorekeeper sheet — pure Kotlin, unit-tested — and its store
 settings/      DataStore-backed preferences

app/src/main/java/org/prolibertate/games/MainActivity.kt

@@ -10,11 +10,14 @@ import org.prolibertate.games.net.LobbyController
 import org.prolibertate.games.net.ScorekeeperSession
 import org.prolibertate.games.score.ScorekeeperRepository
 import org.prolibertate.games.settings.SettingsRepository
+import org.prolibertate.games.settings.YahtzeeStatsRepository
 import org.prolibertate.games.ui.AppEnv
 import org.prolibertate.games.ui.AppRoot
 import org.prolibertate.games.ui.theme.ProLibertateTheme
 import org.prolibertate.games.update.Updater
+import java.io.File
 import java.util.UUID
+import org.prolibertate.games.game.engine.SavedGameStore
 
 class MainActivity : ComponentActivity() {
 
@@ -40,6 +43,8 @@ class MainActivity : ComponentActivity() {
                 deviceId = peerId,
             ),
             peerId = peerId,
+            saves = SavedGameStore(File(filesDir, "saved-games")),
+            yahtzeeStats = YahtzeeStatsRepository(applicationContext),
         )
 
         setContent {

app/src/main/java/org/prolibertate/games/game/Catalog.kt

@@ -106,6 +106,7 @@ object GameCatalog {
     const val TAYU = "tayu"
     const val MORRIS = "morris"
     const val PIRATES = "pirates"
+    const val MEOWDOKU = "meowdoku"
 
     /**
      * The island game the collection is named for. Listed under Board Games
@@ -360,13 +361,19 @@ object GameCatalog {
             minPlayers = 3,
             maxPlayers = 4,
             teamBased = false,
-            blurb = "Trade, build, and settle the island.",
-            // Engine and screen exist but have not been verified on two real
-            // devices yet. Dev builds can open it as a *Preview*; a production
-            // build does not list it. Flip `available` on, and `devPreview`
-            // off, once two-device play has been verified.
-            available = false,
-            devPreview = true,
+            blurb = "Trade, build, and settle the island, in the base game or Cities & Knights.",
+            available = true,
+        ),
+        GameDescriptor(
+            id = MEOWDOKU,
+            title = "Meowdoku",
+            menus = setOf(GameMenu.BOARD, GameMenu.SOLITAIRE),
+            minPlayers = 1,
+            maxPlayers = 1,
+            teamBased = false,
+            blurb = "One cat in every row, column and colour, and no two touching. " +
+                "Wrong taps cost a heart; the board only ever accepts a cat that belongs.",
+            available = true,
         ),
     )
 

app/src/main/java/org/prolibertate/games/game/catan/CatanAi.kt

@@ -20,10 +20,14 @@ import org.prolibertate.games.game.engine.GameAi
  */
 class CatanAi : GameAi<CatanState, CatanMove> {
 
+    /** Plays the Cities & Knights tables; this class keeps the base game. */
+    private val ck = CatanCkAi(this)
+
     override fun chooseMove(state: CatanState, seat: Int, legal: List<CatanMove>): CatanMove {
         require(legal.isNotEmpty() || state.phase == CatanPhase.PLAYING) {
             "No legal move for seat $seat"
         }
+        if (state.isCk) return ck.choose(state, seat, legal)
         return when (state.phase) {
             CatanPhase.SETUP_FIRST, CatanPhase.SETUP_SECOND ->
                 chooseSetup(state, seat, legal.filterIsInstance<SetupPlace>())
@@ -38,10 +42,12 @@ class CatanAi : GameAi<CatanState, CatanMove> {
 
             CatanPhase.TRADE_PENDING -> chooseResponse(state, seat, legal)
 
+            CatanPhase.TRADE_COUNTERS -> chooseCounter(state, legal)
+
             CatanPhase.PLAYING -> choosePlaying(state, seat, legal)
 
-            CatanPhase.GAME_OVER -> legal.firstOrNull()
-                ?: error("The game is over; nobody chooses a move")
+            CatanPhase.CHORE, CatanPhase.GAME_OVER -> legal.firstOrNull()
+                ?: error("Nothing to choose in phase ${state.phase}")
         }
     }
 
@@ -49,7 +55,7 @@ class CatanAi : GameAi<CatanState, CatanMove> {
     // Setup
     // -----------------------------------------------------------------------
 
-    private fun chooseSetup(state: CatanState, seat: Int, places: List<SetupPlace>): SetupPlace {
+    internal fun chooseSetup(state: CatanState, seat: Int, places: List<SetupPlace>): SetupPlace {
         require(places.isNotEmpty()) { "No legal settlement placement" }
         return places.maxByOrNull { place ->
             spotValue(state, place.vertex) +
@@ -260,23 +266,38 @@ class CatanAi : GameAi<CatanState, CatanMove> {
     }
 
     private fun chooseResponse(state: CatanState, seat: Int, legal: List<CatanMove>): CatanMove {
-        val accept = legal.filterIsInstance<AcceptTrade>().firstOrNull() ?: run {
-            return legal.first { it is DeclineTrade }
-        }
-        val offer = state.pendingTrade ?: return legal.first()
-        // Accept when what arrives is worth more than what leaves: a mild
-        // table, not a shark.
-        val incoming = offer.get.sumOf { want(it) }
-        val outgoing = offer.give.sumOf { want(it) }
+        val accept = legal.filterIsInstance<AcceptTrade>().firstOrNull()
+        val offer = state.pendingTrade
+        if (accept == null || offer == null) return legal.first { it is DeclineTrade }
+        // Accept when what arrives (the offerer's give) is worth more than what
+        // leaves (the offerer's get): a mild table, not a shark.
+        val incoming = offer.give.sumOf { want(it) }
+        val outgoing = offer.get.sumOf { want(it) }
         return if (incoming > outgoing) accept else legal.first { it is DeclineTrade }
     }
 
+    /**
+     * Picks the counter-offer that gains the most by the same valuation, or
+     * turns them all down. The AI never counters itself: it only answers.
+     */
+    private fun chooseCounter(state: CatanState, legal: List<CatanMove>): CatanMove {
+        val offer = state.pendingTrade ?: return legal.first()
+        val best = legal.filterIsInstance<AcceptCounter>()
+            .map { choice -> choice to offer.counters.first { it.by == choice.seat } }
+            .maxByOrNull { (_, c) -> c.give.sumOf { want(it) } - c.get.sumOf { want(it) } }
+        if (best != null) {
+            val (choice, c) = best
+            if (c.give.sumOf { want(it) } > c.get.sumOf { want(it) }) return choice
+        }
+        return legal.first { it is DismissCounters }
+    }
+
     // -----------------------------------------------------------------------
     // Valuations
     // -----------------------------------------------------------------------
 
     /** What a seat would think of building on [vertex]: production and ports. */
-    private fun spotValue(state: CatanState, vertex: Int): Double {
+    internal fun spotValue(state: CatanState, vertex: Int): Double {
         if (state.buildings[vertex] != null) return -1.0
         var value = 0.0
         val kinds = mutableSetOf<Resource>()
@@ -297,7 +318,7 @@ class CatanAi : GameAi<CatanState, CatanMove> {
      * What a road on this edge leads to: the best settlement spot it brings
      * within reach, discounted for being one step further out.
      */
-    private fun roadValue(state: CatanState, move: BuildRoad): Double {
+    internal fun roadValue(state: CatanState, move: BuildRoad): Double {
         var best = 0.0
         val (from, to) = CatanBoard.EDGE_VERTICES[move.edge]
         for (endpoint in listOf(from, to)) {
@@ -309,7 +330,7 @@ class CatanAi : GameAi<CatanState, CatanMove> {
     }
 
     /** How much the AI wants to hold one card of [resource]. */
-    private fun want(resource: Resource): Double = when (resource) {
+    internal fun want(resource: Resource): Double = when (resource) {
         Resource.ORE -> 1.20 // the city
         Resource.GRAIN -> 1.15 // the city and the dev cards
         Resource.LUMBER -> 1.0 // every road and settlement

app/src/main/java/org/prolibertate/games/game/catan/CatanCkAi.kt

@@ -0,0 +1,345 @@
+package org.prolibertate.games.game.catan
+
+/**
+ * The computer opponent for Cities & Knights, reached through [CatanAi].
+ *
+ * It plays the same cautious game as the base AI — settle well, raise cities —
+ * and adds the three things this rule set asks of a player: keep enough active
+ * knights standing when the barbarians land, spend commodities on improvements
+ * as soon as it can, and answer every chore the table raises with the card it
+ * values least. It reads only what a player at the table could see, plus its
+ * own hand.
+ *
+ * It is not a strong player. It never moves knights about (they stay where
+ * hired, and are activated when the barbarians draw near), never plays the
+ * progress cards whose value depends on a plan (Inventor, Alchemist, Diplomat,
+ * Deserter, Intrigue), and makes no domestic offers, though it answers them.
+ */
+internal class CatanCkAi(private val ai: CatanAi) {
+
+    fun choose(state: CatanState, seat: Int, legal: List<CatanMove>): CatanMove = when (state.phase) {
+        CatanPhase.SETUP_FIRST, CatanPhase.SETUP_SECOND ->
+            ai.chooseSetup(state, seat, legal.filterIsInstance<SetupPlace>())
+
+        CatanPhase.AWAIT_ROLL -> legal.first { it is RollDice }
+
+        CatanPhase.CHORE -> chooseChore(state, seat, legal)
+
+        CatanPhase.ROBBER -> chooseRobber(state, seat, legal.filterIsInstance<MoveRobber>())
+
+        CatanPhase.FREE_ROADS -> chooseFreeRoad(state, seat, legal)
+
+        CatanPhase.TRADE_PENDING -> chooseResponse(state, seat, legal)
+
+        CatanPhase.TRADE_COUNTERS -> chooseCounter(state, legal)
+
+        CatanPhase.PLAYING -> choosePlaying(state, seat, legal)
+
+        CatanPhase.DISCARDING, CatanPhase.GAME_OVER -> legal.firstOrNull()
+            ?: error("Nothing to choose in phase ${state.phase}")
+    }
+
+    // -----------------------------------------------------------------------
+    // Chores
+    // -----------------------------------------------------------------------
+
+    private fun chooseChore(state: CatanState, seat: Int, legal: List<CatanMove>): CatanMove {
+        val ck = state.ck!!
+        return when (val chore = ck.chores.first()) {
+            is DiscardChore -> {
+                val n = minOf(chore.count, CatanCk.goodsCount(state, seat))
+                DiscardGoods(CatanCk.goodsList(state, seat).sortedBy { worth(state, seat, it) }.take(n))
+            }
+
+            is GiveChore -> {
+                val pool = CatanCk.goodsList(state, seat)
+                    .filter { !chore.commoditiesOnly || it.isCommodity }
+                    .sortedBy { worth(state, seat, it) }
+                GiveGoods(pool.take(minOf(chore.count, pool.size)))
+            }
+
+            is PillageChore ->
+                legal.filterIsInstance<PillageCity>().minByOrNull { production(state, it.vertex) } ?: legal.first()
+
+            is PickDeckChore -> {
+                val picks = legal.filterIsInstance<PickDeck>()
+                picks.maxByOrNull { CatanCk.improvement(state, seat, it.track) } ?: legal.first()
+            }
+
+            is DropProgressChore ->
+                legal.filterIsInstance<DropProgress>().minByOrNull { drop ->
+                    ck.progressHands[seat].first { it.id == drop.card }.kind.let(::cardWorth)
+                } ?: legal.first()
+
+            is MetropolisChore ->
+                legal.filterIsInstance<PlaceMetropolis>().maxByOrNull { production(state, it.vertex) }
+                    ?: legal.first()
+
+            is AqueductChore ->
+                legal.filterIsInstance<TakeAqueduct>().maxByOrNull { ai.want(it.resource) } ?: legal.first()
+
+            is RelocateChore -> legal.first()
+
+            is RemoveKnightChore ->
+                legal.filterIsInstance<RemoveKnight>().minByOrNull {
+                    CatanCk.knightAt(state, it.vertex)?.level ?: 0
+                } ?: legal.first()
+
+            is PlaceKnightChore -> legal.first()
+
+            is SpyChore -> legal.first()
+
+            is SmithChore ->
+                legal.filterIsInstance<PromoteKnight>().firstOrNull() ?: legal.first { it is EndSmith }
+        }
+    }
+
+    // -----------------------------------------------------------------------
+    // The robber
+    // -----------------------------------------------------------------------
+
+    private fun chooseRobber(state: CatanState, seat: Int, moves: List<MoveRobber>): MoveRobber {
+        require(moves.isNotEmpty()) { "No legal robber move" }
+        val points = CatanRules.publicVictoryPoints(state)
+        return moves.maxByOrNull { move ->
+            val hex = CatanBoard.hexIndex.getValue(move.hex)
+            var score = 0.0
+            for (v in CatanBoard.HEX_CORNERS[hex]) {
+                val building = state.buildings[v] ?: continue
+                val worth = if (building.type == BuildingType.CITY) 2 else 1
+                val odds = CatanBoard.numberOdds(state.numbers[hex]) / 36.0
+                score += if (building.owner == seat) -worth * odds else worth * odds
+            }
+            if (move.victim != null) {
+                score += 0.15 * CatanCk.goodsCount(state, move.victim) + 0.3 * points[move.victim]
+            }
+            score
+        } ?: moves.first()
+    }
+
+    // -----------------------------------------------------------------------
+    // The main phase
+    // -----------------------------------------------------------------------
+
+    private fun choosePlaying(state: CatanState, seat: Int, legal: List<CatanMove>): CatanMove {
+        val ck = state.ck!!
+        val soon = ck.barbarians <= 3
+
+        // Chase the robber off a hex it is squatting on.
+        if (ck.attacked) {
+            val onMine = legal.filterIsInstance<ChaseRobber>().firstOrNull()
+            val robberHurtsMe = CatanBoard.HEX_CORNERS[state.robber].any { state.buildings[it]?.owner == seat }
+            if (onMine != null && robberHurtsMe) return onMine
+        }
+
+        // The cheap upgrade first, then the full-price one.
+        legal.filterIsInstance<PlayProgress>()
+            .filter { kindOf(state, seat, it) == ProgressType.MEDICINE }
+            .maxByOrNull { production(state, it.vertex!!) }
+            ?.let { return it }
+
+        legal.filterIsInstance<BuildCity>().maxByOrNull { production(state, it.vertex) }
+            ?.let { return it }
+
+        legal.filterIsInstance<BuildSettlement>().maxByOrNull { ai.spotValue(state, it.vertex) }
+            ?.let { return it }
+
+        // Improvements spend cards nothing else needs. Favour the track furthest along.
+        legal.filterIsInstance<BuyImprovement>()
+            .maxByOrNull { CatanCk.improvement(state, seat, it.track) * 10 + trackLean(it.track) }
+            ?.let { return it }
+
+        // Knights: stand ready by the time the barbarians land.
+        defence(state, seat, legal, soon)?.let { return it }
+
+        progress(state, seat, legal)?.let { return it }
+
+        legal.filterIsInstance<BuildWall>().firstOrNull()?.let {
+            if (CatanCk.goodsCount(state, seat) >= 7) return it
+        }
+
+        legal.filterIsInstance<BuildRoad>()
+            .filter { ai.roadValue(state, it) > 0.1 }
+            .maxByOrNull { ai.roadValue(state, it) }
+            ?.let { return it }
+
+        legal.filterIsInstance<GoodsBankTrade>()
+            .filter { completes(state, seat, it) }
+            .minByOrNull { CatanCk.bankRatio(state, seat, it.give) }
+            ?.let { return it }
+
+        return legal.lastOrNull { it is EndTurn } ?: legal.first()
+    }
+
+    /** Hire, promote and activate so the knights are standing when the barbarians land. */
+    private fun defence(state: CatanState, seat: Int, legal: List<CatanMove>, soon: Boolean): CatanMove? {
+        val mine = CatanCk.knightsOf(state, seat)
+        val grainLeft = state.resources[seat][Resource.GRAIN] ?: 0
+
+        if (soon) {
+            legal.filterIsInstance<ActivateKnight>().firstOrNull()?.let { return it }
+        }
+        val want = if (soon) 4 else 2
+        if (mine.size < want) {
+            legal.filterIsInstance<HireKnight>().maxByOrNull { ai.spotValue(state, it.vertex) }?.let { hire ->
+                // Keep a grain back for waking it, once the ship is close.
+                if (!soon || grainLeft >= 1) return hire
+            }
+        }
+        if (soon || mine.size >= 2) {
+            legal.filterIsInstance<PromoteKnight>().firstOrNull()?.let { return it }
+        }
+        if (soon) {
+            legal.filterIsInstance<ActivateKnight>().firstOrNull()?.let { return it }
+        }
+        return null
+    }
+
+    /** Progress cards worth playing without a plan. */
+    private fun progress(state: CatanState, seat: Int, legal: List<CatanMove>): CatanMove? {
+        val ck = state.ck!!
+        val soon = ck.barbarians <= 4
+        val plays = legal.filterIsInstance<PlayProgress>()
+        fun kindOf(play: PlayProgress) = ck.progressHands[seat].first { it.id == play.card }.kind
+        fun first(kind: ProgressType) = plays.firstOrNull { kindOf(it) == kind }
+
+        first(ProgressType.IRRIGATION)?.let { return it }
+        first(ProgressType.MINING)?.let { return it }
+        first(ProgressType.ENGINEER)?.let { return it }
+        first(ProgressType.SMITH)?.let { return it }
+        first(ProgressType.WEDDING)?.let { return it }
+        if (soon) first(ProgressType.WARLORD)?.let { return it }
+
+        plays.filter { kindOf(it) == ProgressType.MASTER_MERCHANT }
+            .maxByOrNull { play -> play.goods.orEmpty().sumOf { worth(state, seat, it) } }
+            ?.let { return it }
+
+        first(ProgressType.SPY)?.let { return it }
+        first(ProgressType.BISHOP)?.let { return it }
+
+        if (legal.filterIsInstance<BuildRoad>().size >= 2) first(ProgressType.ROAD_BUILDING)?.let { return it }
+
+        // Crane: only when it makes the difference to an improvement.
+        first(ProgressType.CRANE)?.let { crane ->
+            val helps = Track.entries.any { track ->
+                val level = CatanCk.improvement(state, seat, track)
+                val have = ck.commodities[seat][track.commodity] ?: 0
+                level < IMPROVEMENT_MAX && have == level // one short of the next level's price
+            }
+            if (helps) return crane
+        }
+
+        // Saboteur: when someone level or ahead is sitting on a pile.
+        first(ProgressType.SABOTEUR)?.let { saboteur ->
+            val vp = CatanRules.publicVictoryPoints(state)
+            val pile = (0 until state.playerCount).filter { it != seat && vp[it] >= vp[seat] }
+                .sumOf { CatanCk.goodsCount(state, it) / 2 }
+            if (pile >= 4) return saboteur
+        }
+
+        // Monopolies: only when the table is holding a pile of it.
+        plays.filter { kindOf(it) == ProgressType.RESOURCE_MONOPOLY || kindOf(it) == ProgressType.TRADE_MONOPOLY }
+            .maxByOrNull { held(state, seat, it.good!!) }
+            ?.let { best ->
+                val each = if (kindOf(best) == ProgressType.RESOURCE_MONOPOLY) 2 else 1
+                val take = (0 until state.playerCount).filter { it != seat }
+                    .sumOf { minOf(each, CatanCk.goodsOf(state, it)[best.good!!] ?: 0) }
+                if (take >= 3) return best
+            }
+
+        // The merchant, on the best hex beside a building of ours.
+        plays.filter { kindOf(it) == ProgressType.MERCHANT }
+            .maxByOrNull { play ->
+                val hex = play.hexA!!
+                CatanBoard.numberOdds(state.numbers[hex]).toDouble()
+            }?.let { return it }
+
+        // A commercial harbour turns spare resources into commodities.
+        plays.filter { kindOf(it) == ProgressType.COMMERCIAL_HARBOR }
+            .maxByOrNull { held(state, seat, it.good!!) }
+            ?.let { if (held(state, seat, it.good!!) >= 2) return it }
+
+        return null
+    }
+
+    private fun kindOf(state: CatanState, seat: Int, play: PlayProgress): ProgressType =
+        state.ck!!.progressHands[seat].first { it.id == play.card }.kind
+
+    /** What a building on [vertex] would draw, by the odds of its hexes and what the seat wants. */
+    private fun production(state: CatanState, vertex: Int): Double =
+        CatanBoard.VERTEX_HEXES[vertex].sumOf { h ->
+            val want = state.terrains[h].produces?.let { ai.want(it) } ?: 0.0
+            want * CatanBoard.numberOdds(state.numbers[h]) / 36.0
+        }
+
+    private fun held(state: CatanState, seat: Int, good: Good): Int = CatanCk.goodsOf(state, seat)[good] ?: 0
+
+    /** Whether the trade leaves a hand that can pay for a city, a settlement or an improvement. */
+    private fun completes(state: CatanState, seat: Int, trade: GoodsBankTrade): Boolean {
+        val hand = CatanCk.goodsOf(state, seat).toMutableMap()
+        hand[trade.give] = (hand[trade.give] ?: 0) - CatanCk.bankRatio(state, seat, trade.give)
+        hand[trade.get] = (hand[trade.get] ?: 0) + 1
+        fun covers(cost: Map<Resource, Int>) = cost.all { (r, n) -> (hand[Good.of(r)] ?: 0) >= n }
+        if (covers(CatanRules.CITY_COST) || covers(CatanRules.SETTLEMENT_COST)) return true
+        return Track.entries.any { track ->
+            val level = CatanCk.improvement(state, seat, track)
+            level < IMPROVEMENT_MAX &&
+                (hand[Good.of(track.commodity)] ?: 0) >= level + 1 &&
+                (state.ck!!.commodities[seat][track.commodity] ?: 0) < level + 1
+        }
+    }
+
+    private fun chooseFreeRoad(state: CatanState, seat: Int, legal: List<CatanMove>): CatanMove =
+        legal.filterIsInstance<BuildRoad>()
+            .filter { ai.roadValue(state, it) > 0.05 }
+            .maxByOrNull { ai.roadValue(state, it) }
+            ?: legal.firstOrNull { it is EndFreeRoads }
+            ?: legal.first()
+
+    private fun chooseResponse(state: CatanState, seat: Int, legal: List<CatanMove>): CatanMove {
+        val decline = legal.first { it is DeclineTrade }
+        val accept = legal.firstOrNull { it is AcceptTrade } ?: return decline
+        val offer = state.ck?.goodsOffer
+        if (offer != null) {
+            val incoming = offer.give.sumOf { worth(state, seat, it) }
+            val outgoing = offer.get.sumOf { worth(state, seat, it) }
+            return if (incoming > outgoing) accept else decline
+        }
+        val plain = state.pendingTrade ?: return decline
+        val incoming = plain.give.sumOf { ai.want(it) }
+        val outgoing = plain.get.sumOf { ai.want(it) }
+        return if (incoming > outgoing) accept else decline
+    }
+
+    /** Counters to a human's... the AI never makes an offer, so this only guards the phase: take none. */
+    private fun chooseCounter(state: CatanState, legal: List<CatanMove>): CatanMove =
+        legal.firstOrNull { it is DismissCounters } ?: legal.first()
+
+    // -----------------------------------------------------------------------
+    // Valuations
+    // -----------------------------------------------------------------------
+
+    /** What a card is worth to this seat: resources as the base AI sees them, commodities by what they buy. */
+    private fun worth(state: CatanState, seat: Int, good: Good): Double =
+        good.resource?.let { ai.want(it) } ?: when (good) {
+            Good.PAPER -> 0.95
+            Good.COIN -> 0.9
+            else -> 0.85
+        }
+
+    /** Which track to lean toward when two are level: politics for the knights, then science. */
+    private fun trackLean(track: Track): Int = when (track) {
+        Track.POLITICS -> 2
+        Track.SCIENCE -> 1
+        Track.TRADE -> 0
+    }
+
+    private fun cardWorth(kind: ProgressType): Double = when (kind) {
+        ProgressType.INVENTOR, ProgressType.ALCHEMIST, ProgressType.DIPLOMAT,
+        ProgressType.DESERTER, ProgressType.INTRIGUE, ProgressType.MERCHANT_FLEET,
+        -> 0.0
+
+        ProgressType.MERCHANT, ProgressType.COMMERCIAL_HARBOR, ProgressType.CRANE -> 0.5
+        else -> 1.0
+    }
+}

app/src/main/java/org/prolibertate/games/game/catan/CatanCkModel.kt

@@ -0,0 +1,486 @@
+package org.prolibertate.games.game.catan
+
+import kotlinx.serialization.SerialName
+import kotlinx.serialization.Serializable
+
+/*
+ * The data of the Cities & Knights rule set. The rules themselves live in
+ * [CatanCk]; docs/RULES-catan-ck.md describes them and the choices made.
+ *
+ * Everything here is reached through [CatanState.ck], which is null for the
+ * base game, so a base game never sees any of it.
+ */
+
+/** Steps the barbarian ship must make before it lands. */
+const val BARBARIAN_STEPS = 7
+
+/** Commodity cards of each type the bank starts with (resources have 19). */
+const val BANK_PER_COMMODITY = 12
+
+/** Knights of each strength one player owns. */
+const val KNIGHTS_PER_LEVEL = 2
+
+/** City walls one player owns. */
+const val MAX_WALLS = 3
+
+/** Levels of city improvement in each track. */
+const val IMPROVEMENT_MAX = 5
+
+/** Progress cards a player may keep in hand. */
+const val PROGRESS_HAND_MAX = 4
+
+/** Cards a player may hold through a seven, before walls. */
+const val BASE_HAND_LIMIT = 7
+
+/** Longest Road is worth two points here; there is no Largest Army. */
+const val CK_LONGEST_ROAD_VP = 2
+
+/** Improvement level that unlocks the track's special power. */
+const val IMPROVEMENT_POWER_LEVEL = 3
+
+/** Level at which a track can claim its metropolis, and the level that can steal one. */
+const val METROPOLIS_LEVEL = 4
+
+/**
+ * What the three cities-of-industry give in place of a second resource:
+ * forest gives paper, pasture cloth and mountains coin.
+ */
+@Serializable
+enum class Commodity { CLOTH, COIN, PAPER }
+
+/**
+ * Any card a player can hold in hand and trade: a resource or a commodity.
+ * Progress cards are not goods.
+ */
+@Serializable
+enum class Good {
+    LUMBER, BRICK, WOOL, GRAIN, ORE, CLOTH, COIN, PAPER;
+
+    val resource: Resource?
+        get() = when (this) {
+            LUMBER -> Resource.LUMBER
+            BRICK -> Resource.BRICK
+            WOOL -> Resource.WOOL
+            GRAIN -> Resource.GRAIN
+            ORE -> Resource.ORE
+            else -> null
+        }
+
+    val commodity: Commodity?
+        get() = when (this) {
+            CLOTH -> Commodity.CLOTH
+            COIN -> Commodity.COIN
+            PAPER -> Commodity.PAPER
+            else -> null
+        }
+
+    val isCommodity: Boolean get() = commodity != null
+
+    companion object {
+        fun of(resource: Resource): Good = when (resource) {
+            Resource.LUMBER -> LUMBER
+            Resource.BRICK -> BRICK
+            Resource.WOOL -> WOOL
+            Resource.GRAIN -> GRAIN
+            Resource.ORE -> ORE
+        }
+
+        fun of(commodity: Commodity): Good = when (commodity) {
+            Commodity.CLOTH -> CLOTH
+            Commodity.COIN -> COIN
+            Commodity.PAPER -> PAPER
+        }
+
+        val RESOURCES: List<Good> = Resource.entries.map { of(it) }
+        val COMMODITIES: List<Good> = Commodity.entries.map { of(it) }
+    }
+}
+
+/**
+ * The three tracks of city improvement. Each is bought with one commodity, has
+ * a colour of progress-card deck and a power that unlocks at level three.
+ */
+@Serializable
+enum class Track(val commodity: Commodity) {
+    /** Yellow, bought with cloth: trade commodities two for one. */
+    TRADE(Commodity.CLOTH),
+
+    /** Blue, bought with coin: knights may become mighty. */
+    POLITICS(Commodity.COIN),
+
+    /** Green, bought with paper: the aqueduct. */
+    SCIENCE(Commodity.PAPER),
+}
+
+/**
+ * One face of the event die: a ship, or a city gate of a track's colour.
+ * Three faces are ships.
+ */
+@Serializable
+enum class EventFace { SHIP, TRADE, POLITICS, SCIENCE }
+
+/** The progress cards: [copies] of each in the deck of its [track]. */
+@Serializable
+enum class ProgressType(val track: Track, val copies: Int, val scoresAtOnce: Boolean = false) {
+    // Science (green)
+    ALCHEMIST(Track.SCIENCE, 2),
+    CRANE(Track.SCIENCE, 2),
+    ENGINEER(Track.SCIENCE, 1),
+    INVENTOR(Track.SCIENCE, 2),
+    IRRIGATION(Track.SCIENCE, 2),
+    MEDICINE(Track.SCIENCE, 2),
+    MINING(Track.SCIENCE, 2),
+    PRINTER(Track.SCIENCE, 1, scoresAtOnce = true),
+    ROAD_BUILDING(Track.SCIENCE, 2),
+    SMITH(Track.SCIENCE, 2),
+
+    // Politics (blue)
+    BISHOP(Track.POLITICS, 2),
+    CONSTITUTION(Track.POLITICS, 1, scoresAtOnce = true),
+    DESERTER(Track.POLITICS, 2),
+    DIPLOMAT(Track.POLITICS, 2),
+    INTRIGUE(Track.POLITICS, 2),
+    SABOTEUR(Track.POLITICS, 2),
+    SPY(Track.POLITICS, 3),
+    WARLORD(Track.POLITICS, 2),
+    WEDDING(Track.POLITICS, 2),
+
+    // Trade (yellow)
+    COMMERCIAL_HARBOR(Track.TRADE, 2),
+    MASTER_MERCHANT(Track.TRADE, 2),
+    MERCHANT(Track.TRADE, 6),
+    MERCHANT_FLEET(Track.TRADE, 2),
+    RESOURCE_MONOPOLY(Track.TRADE, 4),
+    TRADE_MONOPOLY(Track.TRADE, 2),
+}
+
+/** One progress card; [id] is stable for the life of the game. */
+@Serializable
+data class ProgressCard(val id: Int, val kind: ProgressType)
+
+/**
+ * A knight on the board. [level] is its strength: 1 basic, 2 strong, 3 mighty.
+ *
+ * [activatedTurn] and [promotedTurn] record the turn number each happened on:
+ * a knight cannot act on the turn it was activated, and cannot be promoted twice
+ * in one turn.
+ */
+@Serializable
+data class Knight(
+    val vertex: Int,
+    val owner: Int,
+    val level: Int,
+    val active: Boolean = false,
+    val activatedTurn: Int = 0,
+    val promotedTurn: Int = 0,
+)
+
+/** A metropolis stands on one city: [vertex] of seat [seat]. */
+@Serializable
+data class MetropolisAt(val seat: Int, val vertex: Int)
+
+/** The merchant sits on a hex, controlled by [seat] (who holds its point). */
+@Serializable
+data class MerchantAt(val seat: Int, val hex: Int)
+
+/** A counter-proposal to a [GoodsOffer]: seat [by] would [give] these if the offerer handed over [get]. */
+@Serializable
+data class GoodsCounter(val by: Int, val give: List<Good>, val get: List<Good>)
+
+/**
+ * A domestic trade offer in goods, which may include commodities. It is the
+ * base game's [TradeOffer] in cards of any kind, and works the same way: [to] is
+ * the one seat it is addressed to or null for the whole table, [asking] is the
+ * seat that may answer now, and [counters] collect for the offerer to choose from.
+ */
+@Serializable
+data class GoodsOffer(
+    val by: Int,
+    val to: Int?,
+    val give: List<Good>,
+    val get: List<Good>,
+    val asking: Int = to ?: -1,
+    val counters: List<GoodsCounter> = emptyList(),
+)
+
+/** Where play goes when the queue of [Chore]s runs out. */
+@Serializable
+enum class Back { PLAYING, AWAIT_ROLL, AFTER_EVENT, AFTER_DISCARDS, AFTER_PRODUCTION }
+
+/**
+ * Something one seat must decide before the game can go on. A chore is queued
+ * when a roll, an attack or a card needs an answer from somebody (possibly not
+ * the player whose turn it is); the first in [CkState.chores] is the one being
+ * asked.
+ */
+@Serializable
+sealed interface Chore {
+    val seat: Int
+}
+
+/** Give [count] cards to the bank, of the seat's choosing (a seven, a saboteur). */
+@Serializable
+@SerialName("c_discard")
+data class DiscardChore(override val seat: Int, val count: Int) : Chore
+
+/**
+ * Hand [count] cards of the seat's choosing to seat [to] (a wedding, a
+ * commercial harbour). [commoditiesOnly] restricts them to commodities, and
+ * [reward] is the resource [to] gives back for each.
+ */
+@Serializable
+@SerialName("c_give")
+data class GiveChore(
+    override val seat: Int,
+    val count: Int,
+    val to: Int,
+    val commoditiesOnly: Boolean = false,
+    val reward: Good? = null,
+) : Chore
+
+/** The barbarians won and this seat lost the contest: pick a city to fall. */
+@Serializable
+@SerialName("c_pillage")
+data class PillageChore(override val seat: Int) : Chore
+
+/** Choose a colour of progress deck to draw from. */
+@Serializable
+@SerialName("c_pickDeck")
+data class PickDeckChore(override val seat: Int) : Chore
+
+/** More progress cards than the hand holds: give one back. */
+@Serializable
+@SerialName("c_dropProgress")
+data class DropProgressChore(override val seat: Int) : Chore
+
+/** Choose the city that will bear the [track] metropolis. */
+@Serializable
+@SerialName("c_metropolis")
+data class MetropolisChore(override val seat: Int, val track: Track) : Chore
+
+/** The aqueduct pays out: take any one resource. */
+@Serializable
+@SerialName("c_aqueduct")
+data class AqueductChore(override val seat: Int) : Chore
+
+/** A knight was driven from its place; move it, or lose it. [knight] stood on [Knight.vertex]. */
+@Serializable
+@SerialName("c_relocate")
+data class RelocateChore(override val seat: Int, val knight: Knight) : Chore
+
+/** A deserter was played against this seat: remove one of your knights. */
+@Serializable
+@SerialName("c_removeKnight")
+data class RemoveKnightChore(override val seat: Int, val by: Int) : Chore
+
+/** Place a knight of [level] on the board for free, active or not as given. */
+@Serializable
+@SerialName("c_placeKnight")
+data class PlaceKnightChore(override val seat: Int, val level: Int, val active: Boolean) : Chore
+
+/** Choose one of [target]'s progress cards to take. */
+@Serializable
+@SerialName("c_spy")
+data class SpyChore(override val seat: Int, val target: Int) : Chore
+
+/** Promote up to [left] more knights for free. */
+@Serializable
+@SerialName("c_smith")
+data class SmithChore(override val seat: Int, val left: Int) : Chore
+
+/**
+ * Everything Cities & Knights adds to the table.
+ *
+ * Counts that are public ([progressCounts], the knights, the improvement
+ * levels) are stored directly; the decks and the other seats' progress hands are
+ * here in full because the host owns the truth, and [CatanRules.viewFor] keeps
+ * them off the wire.
+ */
+@Serializable
+data class CkState(
+    /** Commodity cards per seat. */
+    val commodities: List<Map<Commodity, Int>>,
+    /** Improvement level (0..5) per seat and track. */
+    val improvements: List<Map<Track, Int>>,
+    /** The metropolis of each track that has one. */
+    val metropolises: Map<Track, MetropolisAt> = emptyMap(),
+    val knights: List<Knight> = emptyList(),
+    /** Vertices whose city has a wall. */
+    val walls: List<Int> = emptyList(),
+    /** Steps left before the barbarians land, [BARBARIAN_STEPS] at the start. */
+    val barbarians: Int = BARBARIAN_STEPS,
+    /** Whether the barbarians have landed once: until then the robber sleeps. */
+    val attacked: Boolean = false,
+    val eventDie: EventFace? = null,
+    /** Progress decks, top first. Order is hidden. */
+    val decks: Map<Track, List<ProgressCard>>,
+    val progressHands: List<List<ProgressCard>>,
+    /** Public mirror of the progress-hand sizes. */
+    val progressCounts: List<Int>,
+    /** Victory points from Constitution and Printer, played face up at once. */
+    val progressVp: List<Int>,
+    /** Defender of Catan cards won, one point each. */
+    val defenderVp: List<Int>,
+    val merchant: MerchantAt? = null,
+    /** A crane was played this turn and its discount is unspent. */
+    val crane: Boolean = false,
+    /** A merchant fleet was played this turn for this good. */
+    val fleet: Good? = null,
+    /** Dice named by an alchemist, used by the next roll. */
+    val alchemist: List<Int>? = null,
+    /** The robber is being moved by a bishop, which robs everyone nearby. */
+    val bishop: Boolean = false,
+    val chores: List<Chore> = emptyList(),
+    val back: Back = Back.PLAYING,
+    val goodsOffer: GoodsOffer? = null,
+    /** Seats that have already drawn a defender or winners' card this attack, for the log only. */
+    val lastAttack: String? = null,
+)
+
+// ---------------------------------------------------------------------------
+// Moves
+// ---------------------------------------------------------------------------
+
+/** Buy the next level of improvement in [track]. */
+@Serializable
+@SerialName("buyImprovement")
+data class BuyImprovement(val track: Track) : CatanMove
+
+/** Hire a basic knight onto [vertex], an empty crossing at the end of one of your roads. */
+@Serializable
+@SerialName("hireKnight")
+data class HireKnight(val vertex: Int) : CatanMove
+
+/** Pay a grain to activate the knight on [vertex]. */
+@Serializable
+@SerialName("activateKnight")
+data class ActivateKnight(val vertex: Int) : CatanMove
+
+/** Promote the knight on [vertex] one level (paid, or free under a Smith). */
+@Serializable
+@SerialName("promoteKnight")
+data class PromoteKnight(val vertex: Int) : CatanMove
+
+/** Move the active knight on [from] along your roads to [to], driving off a weaker knight there. */
+@Serializable
+@SerialName("moveKnight")
+data class MoveKnight(val from: Int, val to: Int) : CatanMove
+
+/** The active knight on [vertex] chases the robber; the robber move follows. */
+@Serializable
+@SerialName("chaseRobber")
+data class ChaseRobber(val vertex: Int) : CatanMove
+
+/** Raise a wall around the city on [vertex]. */
+@Serializable
+@SerialName("buildWall")
+data class BuildWall(val vertex: Int) : CatanMove
+
+/**
+ * Play a progress card. Which of the optional arguments are used depends on
+ * the card (see [CatanCk]); the engine's legal list names every combination it
+ * accepts, so a client only ever chooses among them.
+ */
+@Serializable
+@SerialName("progress")
+data class PlayProgress(
+    val card: Int,
+    val target: Int? = null,
+    val vertex: Int? = null,
+    val edge: Int? = null,
+    val hexA: Int? = null,
+    val hexB: Int? = null,
+    val good: Good? = null,
+    val dice: List<Int>? = null,
+    val goods: List<Good>? = null,
+) : CatanMove
+
+/**
+ * Trade [give] to the bank for [get], at the best ratio this seat has for the
+ * card it gives. Replaces [MaritimeTrade] in Cities & Knights, where
+ * commodities trade too.
+ */
+@Serializable
+@SerialName("goodsBank")
+data class GoodsBankTrade(val give: Good, val get: Good) : CatanMove
+
+/**
+ * Offer a trade in goods to seat [to], or to the whole table when [to] is null.
+ * Free-form like [OfferTrade], so it is checked structurally and is not in the
+ * enumerated move list.
+ */
+@Serializable
+@SerialName("offerGoods")
+data class OfferGoods(val to: Int?, val give: List<Good>, val get: List<Good>) : CatanMove
+
+/**
+ * Answer the goods offer on the table with different terms. Structural, like
+ * [OfferGoods]; the answers to the counters are the shared [AcceptCounter] and
+ * [DismissCounters].
+ */
+@Serializable
+@SerialName("counterGoods")
+data class CounterGoods(val give: List<Good>, val get: List<Good>) : CatanMove
+
+/**
+ * Give up exactly the cards named, to a [DiscardChore]. Structural, not
+ * enumerated; the legal list carries one example so a seat is never without a move.
+ */
+@Serializable
+@SerialName("discardGoods")
+data class DiscardGoods(val cards: List<Good>) : CatanMove
+
+/** Hand over the cards named to a [GiveChore]. Structural, like [DiscardGoods]. */
+@Serializable
+@SerialName("giveGoods")
+data class GiveGoods(val cards: List<Good>) : CatanMove
+
+/** Let the city on [vertex] fall to the barbarians. */
+@Serializable
+@SerialName("pillageCity")
+data class PillageCity(val vertex: Int) : CatanMove
+
+/** Draw from the deck of this track's colour. */
+@Serializable
+@SerialName("pickDeck")
+data class PickDeck(val track: Track) : CatanMove
+
+/** Give up one progress card from a hand that is over the limit. */
+@Serializable
+@SerialName("dropProgress")
+data class DropProgress(val card: Int) : CatanMove
+
+/** Put the metropolis on the city at [vertex]. */
+@Serializable
+@SerialName("placeMetropolis")
+data class PlaceMetropolis(val vertex: Int) : CatanMove
+
+/** Take one [resource] from the bank for an aqueduct. */
+@Serializable
+@SerialName("aqueduct")
+data class TakeAqueduct(val resource: Resource) : CatanMove
+
+/** Move the knight that was driven off to [to]. */
+@Serializable
+@SerialName("relocateKnight")
+data class RelocateKnight(val to: Int) : CatanMove
+
+/** Take the knight on [vertex] off the board, for a deserter. */
+@Serializable
+@SerialName("removeKnight")
+data class RemoveKnight(val vertex: Int) : CatanMove
+
+/** Place the free knight from a deserter on [vertex]. */
+@Serializable
+@SerialName("placeKnight")
+data class PlaceKnight(val vertex: Int) : CatanMove
+
+/** Take the spied progress card with this id. */
+@Serializable
+@SerialName("spyTake")
+data class SpyTake(val card: Int) : CatanMove
+
+/** Stop promoting knights under a Smith. */
+@Serializable
+@SerialName("endSmith")
+data object EndSmith : CatanMove

app/src/main/java/org/prolibertate/games/game/catan/CatanModel.kt

@@ -74,17 +74,34 @@ enum class DevCardType { KNIGHT, ROAD_BUILDING, MONOPOLY, YEAR_OF_PLENTY, VICTOR
 data class DevCard(val id: Int, val type: DevCardType, val boughtTurn: Int = 0)
 
 /**
- * A domestic trade offer on the table. [by] is the offering seat and [to]
- * the only seat that may respond — v1 has no counter-offers and no open
- * auctions, so an offer is always addressed to one player.
+ * A counter-proposal to a [TradeOffer]: seat [by] would [give] these cards to
+ * the offerer if the offerer would hand over [get].
  */
 @Serializable
-data class TradeOffer(val by: Int, val to: Int, val give: List<Resource>, val get: List<Resource>)
+data class TradeCounter(val by: Int, val give: List<Resource>, val get: List<Resource>)
+
+/**
+ * A domestic trade offer on the table. [by] is the offering seat. [to] is the
+ * one seat it is addressed to, or null for an open offer to the whole table.
+ * Seats are asked one at a time, in seat order after the offerer; [asking] is
+ * the seat that may answer now. Each may accept (the trade happens at once),
+ * decline, or counter; counters are kept in [counters] and, if nobody accepts,
+ * the offerer chooses among them in [CatanPhase.TRADE_COUNTERS].
+ */
+@Serializable
+data class TradeOffer(
+    val by: Int,
+    val to: Int?,
+    val give: List<Resource>,
+    val get: List<Resource>,
+    val asking: Int = to ?: -1,
+    val counters: List<TradeCounter> = emptyList(),
+)
 
 /**
  * Where the game stands. The phases that involve more than the player
  * whose turn it is carry their own bookkeeping: [discardSeat] during
- * [CatanPhase.DISCARDING], [pendingTrade] during [CatanPhase.TRADE_PENDING].
+ * [CatanPhase.DISCARDING], [pendingTrade] during [CatanPhase.TRADE_PENDING] and [CatanPhase.TRADE_COUNTERS].
  */
 @Serializable
 enum class CatanPhase {
@@ -109,16 +126,37 @@ enum class CatanPhase {
     /** A played Road Building card: up to two roads remain to be placed. */
     FREE_ROADS,
 
-    /** The offered seat must accept or decline. */
+    /** The [TradeOffer.asking] seat must accept, decline or counter. */
     TRADE_PENDING,
 
+    /** Nobody accepted but some seats countered: the offerer picks one or none. */
+    TRADE_COUNTERS,
+
     GAME_OVER,
+
+    /**
+     * Cities & Knights only: the first seat in [CkState.chores] has something
+     * to decide (a discard, a city to give up, a card to draw…) and the game
+     * waits on it. Play resumes where [CkState.back] says.
+     */
+    CHORE,
+}
+
+/** Which rules a table plays. The expansion is a whole rule set, not a toggle. */
+@Serializable
+enum class CatanRuleSet {
+    /** The base game: development cards, Largest Army, a robber from the start. */
+    BASE,
+
+    /** Cities & Knights: commodities, knights, barbarians, city improvements. */
+    CITIES_AND_KNIGHTS,
 }
 
 @Serializable
 data class CatanOptions(
     val playerCount: Int = 3,
     val pointsToWin: Int = 10,
+    val ruleSet: CatanRuleSet = CatanRuleSet.BASE,
 ) {
     init {
         require(playerCount in 3..4) { "The island seats three or four players" }
@@ -190,9 +228,14 @@ data class CatanState(
     val rngStep: Int,
     val winner: Int?,
     val log: List<String>,
+    /** Everything Cities & Knights adds; null in the base game. */
+    val ck: CkState? = null,
 ) {
     val playerCount: Int get() = options.playerCount
 
+    /** Whether this table plays Cities & Knights. */
+    val isCk: Boolean get() = ck != null
+
     /** Total resource cards held by [seat]. */
     fun resourceCount(seat: Int): Int = resources[seat].values.sum()
 
@@ -227,7 +270,11 @@ data class SetupPlace(val vertex: Int, val edge: Int) : CatanMove
  */
 @Serializable
 @SerialName("roll")
-data class RollDice(val forced: List<Int>? = null) : CatanMove
+data class RollDice(
+    val forced: List<Int>? = null,
+    /** Test-only, like [forced]: the event die of a Cities & Knights roll. */
+    val event: EventFace? = null,
+) : CatanMove
 
 /** Discard exactly these cards. */
 @Serializable
@@ -278,7 +325,8 @@ data class PlayMonopoly(val card: Int, val resource: Resource) : CatanMove
 data class PlayYearOfPlenty(val card: Int, val take: List<Resource>) : CatanMove
 
 /**
- * Offer a domestic trade to [to]: [give] of ours for [get] of theirs.
+ * Offer a domestic trade to [to] (null: everyone, asked in turn): [give] of
+ * ours for [get] of theirs.
  *
  * Like a forced dice roll this is a free-form intent rather than an
  * enumerated move — the space of two card multisets is combinatorial — so
@@ -287,7 +335,7 @@ data class PlayYearOfPlenty(val card: Int, val take: List<Resource>) : CatanMove
  */
 @Serializable
 @SerialName("offer")
-data class OfferTrade(val to: Int, val give: List<Resource>, val get: List<Resource>) : CatanMove
+data class OfferTrade(val to: Int?, val give: List<Resource>, val get: List<Resource>) : CatanMove
 
 @Serializable
 @SerialName("accept")
@@ -297,6 +345,25 @@ data object AcceptTrade : CatanMove
 @SerialName("decline")
 data object DeclineTrade : CatanMove
 
+/**
+ * Answer the offer on the table with different terms: we would [give] these
+ * cards if the offerer handed over [get]. Free-form like [OfferTrade], so
+ * validated by [CatanRules.isLegalMove] rather than listed.
+ */
+@Serializable
+@SerialName("counter")
+data class CounterTrade(val give: List<Resource>, val get: List<Resource>) : CatanMove
+
+/** The offerer takes the counter-proposal made by [seat]. */
+@Serializable
+@SerialName("acceptCounter")
+data class AcceptCounter(val seat: Int) : CatanMove
+
+/** The offerer takes none of the counter-proposals. */
+@Serializable
+@SerialName("dismissCounters")
+data object DismissCounters : CatanMove
+
 /** Bank trade: [give] at the best ratio this seat can trade at for [get]. */
 @Serializable
 @SerialName("bank")

app/src/main/java/org/prolibertate/games/game/catan/CatanRules.kt

@@ -57,9 +57,16 @@ object CatanRules : GameRules<CatanState, CatanMove> {
         val board = CatanBoard.generate(config.seed)
         // A different random stream than the island, so the same seed still
         // produces both a fixed island and a fixed deck.
-        val devDeck = DEV_DECK
-            .mapIndexed { id, type -> DevCard(id, type) }
-            .shuffled(Random(config.seed + 1))
+        val ck = options.ruleSet == CatanRuleSet.CITIES_AND_KNIGHTS
+        // Cities & Knights has no development cards: knights and progress
+        // cards take their place.
+        val devDeck = if (ck) {
+            emptyList()
+        } else {
+            DEV_DECK
+                .mapIndexed { id, type -> DevCard(id, type) }
+                .shuffled(Random(config.seed + 1))
+        }
 
         return CatanState(
             options = options,
@@ -91,8 +98,10 @@ object CatanRules : GameRules<CatanState, CatanMove> {
             rngStep = 0,
             winner = null,
             log = listOf(
-                "Catan — ${options.playerCount} players, first to ${options.pointsToWin} victory points.",
+                "Catan${if (ck) " — Cities & Knights" else ""} — ${options.playerCount} players, " +
+                    "first to ${options.pointsToWin} victory points.",
             ),
+            ck = if (ck) CatanCk.initial(options, config.seed) else null,
         )
     }
 
@@ -101,7 +110,10 @@ object CatanRules : GameRules<CatanState, CatanMove> {
         CatanPhase.SETUP_FIRST -> state.setupIndex
         CatanPhase.SETUP_SECOND -> 2 * state.playerCount - 1 - state.setupIndex
         CatanPhase.DISCARDING -> state.discardSeat
-        CatanPhase.TRADE_PENDING -> state.pendingTrade?.to
+        CatanPhase.TRADE_PENDING -> state.pendingTrade?.asking?.takeIf { it >= 0 }
+            ?: state.ck?.goodsOffer?.asking?.takeIf { it >= 0 }
+        CatanPhase.TRADE_COUNTERS -> state.turn
+        CatanPhase.CHORE -> state.ck?.chores?.firstOrNull()?.seat
         CatanPhase.AWAIT_ROLL, CatanPhase.ROBBER,
         CatanPhase.PLAYING, CatanPhase.FREE_ROADS,
         -> state.turn
@@ -130,12 +142,19 @@ object CatanRules : GameRules<CatanState, CatanMove> {
 
             is OfferTrade -> offerLegal(state, seat, move)
 
-            else -> move in legalMoves(state, seat)
+            is CounterTrade -> counterLegal(state, seat, move)
+
+            else -> if (state.isCk) {
+                CatanCk.structurallyLegal(state, seat, move) ?: (move in legalMoves(state, seat))
+            } else {
+                move in legalMoves(state, seat)
+            }
         }
     }
 
     override fun legalMoves(state: CatanState, seat: Int): List<CatanMove> {
         if (currentSeat(state) != seat) return emptyList()
+        if (state.isCk) return CatanCk.legalMoves(state, seat)
         return when (state.phase) {
             CatanPhase.SETUP_FIRST, CatanPhase.SETUP_SECOND -> setupMoves(state)
 
@@ -152,11 +171,13 @@ object CatanRules : GameRules<CatanState, CatanMove> {
 
             CatanPhase.TRADE_PENDING -> tradeResponses(state, seat)
 
-            CatanPhase.GAME_OVER -> emptyList()
+            CatanPhase.TRADE_COUNTERS -> counterChoices(state)
+
+            CatanPhase.CHORE, CatanPhase.GAME_OVER -> emptyList()
         }
     }
 
-    private fun setupMoves(state: CatanState): List<SetupPlace> {
+    internal fun setupMoves(state: CatanState): List<SetupPlace> {
         val moves = mutableListOf<SetupPlace>()
         for (v in 0 until CatanBoard.VERTEX_COUNT) {
             if (!vertexOpenForSettlement(state, v)) continue
@@ -276,7 +297,7 @@ object CatanRules : GameRules<CatanState, CatanMove> {
      * Road placements that connect to [seat]'s network, cost aside. A player
      * with all fifteen roads laid has none.
      */
-    private fun roadMoves(state: CatanState, seat: Int): List<BuildRoad> =
+    internal fun roadMoves(state: CatanState, seat: Int): List<BuildRoad> =
         if (state.roads.count { it == seat } >= MAX_ROADS) {
             emptyList()
         } else {
@@ -291,7 +312,7 @@ object CatanRules : GameRules<CatanState, CatanMove> {
      * connection requirement does not apply — that is why setup uses its
      * own move.)
      */
-    private fun settlementVertices(state: CatanState, seat: Int): List<Int> =
+    internal fun settlementVertices(state: CatanState, seat: Int): List<Int> =
         if (piecesOf(state, seat, BuildingType.SETTLEMENT) >= MAX_SETTLEMENTS) {
             emptyList()
         } else {
@@ -301,7 +322,7 @@ object CatanRules : GameRules<CatanState, CatanMove> {
             }
         }
 
-    private fun cityVertices(state: CatanState, seat: Int): List<Int> =
+    internal fun cityVertices(state: CatanState, seat: Int): List<Int> =
         if (piecesOf(state, seat, BuildingType.CITY) >= MAX_CITIES) {
             emptyList()
         } else {
@@ -310,11 +331,14 @@ object CatanRules : GameRules<CatanState, CatanMove> {
             }
         }
 
+    private fun hasKnight(state: CatanState, vertex: Int): Boolean =
+        state.ck?.knights?.any { it.vertex == vertex } == true
+
     /** How many settlements or cities [seat] currently has standing. */
     private fun piecesOf(state: CatanState, seat: Int, type: BuildingType): Int =
         state.buildings.count { it?.owner == seat && it.type == type }
 
-    private fun tradeResponses(state: CatanState, seat: Int): List<CatanMove> {
+    internal fun tradeResponses(state: CatanState, seat: Int): List<CatanMove> {
         val offer = state.pendingTrade ?: return emptyList()
         val responses = mutableListOf<CatanMove>()
         if (state.holdsAll(seat, offer.get) && state.holdsAll(offer.by, offer.give)) {
@@ -324,9 +348,32 @@ object CatanRules : GameRules<CatanState, CatanMove> {
         return responses
     }
 
+    /** What the offerer may do with the counters: take one that is still affordable, or none. */
+    internal fun counterChoices(state: CatanState): List<CatanMove> {
+        val offer = state.pendingTrade ?: return emptyList()
+        val moves = mutableListOf<CatanMove>()
+        for (counter in offer.counters) {
+            if (state.holdsAll(counter.by, counter.give) && state.holdsAll(offer.by, counter.get)) {
+                moves += AcceptCounter(counter.by)
+            }
+        }
+        moves += DismissCounters
+        return moves
+    }
+
+    private fun counterLegal(state: CatanState, seat: Int, move: CounterTrade): Boolean {
+        val offer = state.pendingTrade ?: return false
+        if (state.phase != CatanPhase.TRADE_PENDING || offer.asking != seat) return false
+        if (move.give.isEmpty() || move.get.isEmpty()) return false
+        if (countOf(move.give) == countOf(move.get)) return false
+        // Taking the offer as made is Accept, not a counter.
+        if (countOf(move.give) == countOf(offer.get) && countOf(move.get) == countOf(offer.give)) return false
+        return state.holdsAll(seat, move.give) && state.holdsAll(offer.by, move.get)
+    }
+
     /** An empty vertex with no building on it or one edge away. */
-    private fun vertexOpenForSettlement(state: CatanState, v: Int): Boolean =
-        state.buildings[v] == null &&
+    internal fun vertexOpenForSettlement(state: CatanState, v: Int): Boolean =
+        state.buildings[v] == null && !hasKnight(state, v) &&
             CatanBoard.VERTEX_NEIGHBORS[v].all { state.buildings[it] == null }
 
     /**
@@ -345,6 +392,9 @@ object CatanRules : GameRules<CatanState, CatanMove> {
     /** Whether [seat]'s roads and buildings reach [vertex] so a road may start there. */
     private fun networkReaches(state: CatanState, seat: Int, vertex: Int): Boolean {
         val building = state.buildings[vertex]
+        // A knight is a wall to everyone but its owner, like a building.
+        val knight = state.ck?.knights?.firstOrNull { it.vertex == vertex }
+        if (knight != null && knight.owner != seat) return false
         // Your own building is always a way in; anyone else's is a wall.
         if (building != null) return building.owner == seat
         return CatanBoard.VERTEX_EDGES[vertex].any { state.roads[it] == seat }
@@ -352,7 +402,7 @@ object CatanRules : GameRules<CatanState, CatanMove> {
 
     private fun offerLegal(state: CatanState, seat: Int, move: OfferTrade): Boolean {
         if (state.phase != CatanPhase.PLAYING || state.turn != seat) return false
-        if (move.to !in 0 until state.playerCount || move.to == seat) return false
+        if (move.to != null && (move.to !in 0 until state.playerCount || move.to == seat)) return false
         if (move.give.isEmpty() || move.get.isEmpty()) return false
         // Like-for-like is not a trade; the published game rejects it too.
         if (countOf(move.give) == countOf(move.get)) return false
@@ -384,21 +434,28 @@ object CatanRules : GameRules<CatanState, CatanMove> {
             is OfferTrade -> applyOfferTrade(state, seat, move)
             AcceptTrade -> applyAcceptTrade(state, seat)
             DeclineTrade -> applyDeclineTrade(state, seat)
+            is CounterTrade -> applyCounterTrade(state, seat, move)
+            is AcceptCounter -> applyAcceptCounter(state, move)
+            DismissCounters -> applyDismissCounters(state)
             is MaritimeTrade -> applyMaritimeTrade(state, seat, move)
             EndTurn -> applyEndTurn(state, seat)
             EndFreeRoads -> applyEndFreeRoads(state, seat)
-        }
+            else -> CatanCk.apply(state, seat, move)
+        }.let { if (it.isCk) CatanCk.settle(it) else it }
     }
 
     private fun applySetup(state: CatanState, seat: Int, move: SetupPlace): CatanState {
         val n = state.playerCount
         val second = state.phase == CatanPhase.SETUP_SECOND
+        // In Cities & Knights the second placement is a city.
+        val first = if (state.isCk && second) BuildingType.CITY else BuildingType.SETTLEMENT
         var s = state.copy(
             buildings = state.buildings.toMutableList().also {
-                it[move.vertex] = CatanBuilding(BuildingType.SETTLEMENT, seat)
+                it[move.vertex] = CatanBuilding(first, seat)
             },
             roads = state.roads.toMutableList().also { it[move.edge] = seat },
-            log = state.log + "Seat $seat settles at ${move.vertex} and lays a road on ${move.edge}.",
+            log = state.log + ("Seat $seat ${if (first == BuildingType.CITY) "raises a city" else "settles"} " +
+                "at ${move.vertex} and lays a road on ${move.edge}."),
         )
 
         if (second) {
@@ -432,6 +489,7 @@ object CatanRules : GameRules<CatanState, CatanMove> {
     }
 
     private fun applyRoll(state: CatanState, seat: Int, move: RollDice): CatanState {
+        if (state.isCk) return CatanCk.applyRoll(state, seat, move)
         val dice = move.forced ?: derivedDice(state)
         val total = dice[0] + dice[1]
         val s = state.copy(lastDice = dice, rngStep = state.rngStep + 1)
@@ -506,6 +564,7 @@ object CatanRules : GameRules<CatanState, CatanMove> {
         ((after + 1) until state.playerCount).firstOrNull { state.resourceCount(it) > 7 }
 
     private fun applyRobber(state: CatanState, seat: Int, move: MoveRobber): CatanState {
+        if (state.isCk) return CatanCk.applyRobber(state, seat, move)
         val hex = CatanBoard.hexIndex[move.hex]
             ?: throw IllegalArgumentException("No hex at ${move.hex}")
         var s = state.copy(robber = hex, rngStep = state.rngStep + 1)
@@ -522,8 +581,8 @@ object CatanRules : GameRules<CatanState, CatanMove> {
         }
         return s.copy(
             phase = CatanPhase.PLAYING,
-            log = s.log + "Seat $seat moves the robber to the ${terrainName(state.terrains[hex])}" +
-                " (${move.hex.q},${move.hex.r})$stolen.",
+            log = s.log + ("Seat $seat moves the robber to the ${terrainName(state.terrains[hex])}" +
+                " (${move.hex.q},${move.hex.r})$stolen."),
         )
     }
 
@@ -535,7 +594,7 @@ object CatanRules : GameRules<CatanState, CatanMove> {
         if (free) {
             val left = s.pendingFreeRoads - 1
             s = s.copy(pendingFreeRoads = left)
-            if (left == 0) s = s.copy(phase = CatanPhase.PLAYING)
+            if (left == 0) s = s.copy(phase = phaseAfterRoads(s))
         }
         return checkWin(s.copy(log = s.log + "Seat $seat builds a road on ${move.edge}."))
     }
@@ -560,7 +619,10 @@ object CatanRules : GameRules<CatanState, CatanMove> {
             },
         )
         s = payCost(s, seat, CITY_COST)
-        return checkWin(s.copy(log = s.log + "Seat $seat raises a city at ${move.vertex}."))
+        s = s.copy(log = s.log + "Seat $seat raises a city at ${move.vertex}.")
+        // A city can be what a waiting metropolis needed.
+        if (s.isCk) s = CatanCk.afterCityBuilt(s, seat)
+        return checkWin(s)
     }
 
     private fun applyBuyDevCard(state: CatanState, seat: Int): CatanState {
@@ -633,33 +695,117 @@ object CatanRules : GameRules<CatanState, CatanMove> {
         )
     }
 
-    private fun applyOfferTrade(state: CatanState, seat: Int, move: OfferTrade): CatanState =
-        state.copy(
-            phase = CatanPhase.TRADE_PENDING,
-            pendingTrade = TradeOffer(by = seat, to = move.to, give = move.give, get = move.get),
+    private fun applyOfferTrade(state: CatanState, seat: Int, move: OfferTrade): CatanState {
+        val audience = if (move.to == null) "the table" else "seat ${move.to}"
+        val offered = state.copy(
             log = state.log + "Seat $seat offers ${describe(countOf(move.give))} for " +
-                "${describe(countOf(move.get))} to seat ${move.to}.",
+                "${describe(countOf(move.get))} to $audience.",
         )
+        val offer = TradeOffer(by = seat, to = move.to, give = move.give, get = move.get)
+        val first = nextAsker(offered, offer, seat)
+            ?: return offered.copy(log = offered.log + "Nobody has any cards to trade.")
+        return offered.copy(
+            phase = CatanPhase.TRADE_PENDING,
+            pendingTrade = offer.copy(asking = first),
+        )
+    }
 
-    private fun applyAcceptTrade(state: CatanState, seat: Int): CatanState {
-        val offer = state.pendingTrade!!
-        var resources = withCards(state.resources, offer.to, offer.get, -1)
-        resources = withCards(resources, offer.by, offer.give, -1)
-        resources = withCards(resources, offer.by, offer.get, 1)
-        resources = withCards(resources, offer.to, offer.give, 1)
+    /**
+     * The next seat to ask after [after], or null when the round is over. An
+     * addressed offer asks only its addressee; an open one walks the table in
+     * seat order, skipping seats with no cards (they could neither pay nor counter).
+     */
+    private fun nextAsker(state: CatanState, offer: TradeOffer, after: Int): Int? {
+        if (offer.to != null) return if (after == offer.by) offer.to else null
+        var s = (after + 1) % state.playerCount
+        while (s != offer.by) {
+            if (state.resourceCount(s) > 0) return s
+            s = (s + 1) % state.playerCount
+        }
+        return null
+    }
+
+    /** Moves the offer on to the next seat, or closes the round when everyone has answered. */
+    private fun advanceTrade(state: CatanState, offer: TradeOffer, after: Int, said: String): CatanState {
+        val next = nextAsker(state, offer, after)
+        val log = state.log + said
+        if (next != null) {
+            return state.copy(pendingTrade = offer.copy(asking = next), log = log)
+        }
+        if (offer.counters.isNotEmpty()) {
+            return state.copy(
+                phase = CatanPhase.TRADE_COUNTERS,
+                pendingTrade = offer.copy(asking = -1),
+                log = log,
+            )
+        }
         return state.copy(
             phase = CatanPhase.PLAYING,
             pendingTrade = null,
-            resources = resources,
+            log = log + "Nobody takes the offer.",
+        )
+    }
+
+    /** Seat [a] hands [aGives] to seat [b] and gets [bGives] back. */
+    private fun swapCards(
+        resources: List<Map<Resource, Int>>,
+        a: Int,
+        aGives: List<Resource>,
+        b: Int,
+        bGives: List<Resource>,
+    ): List<Map<Resource, Int>> {
+        var r = withCards(resources, a, aGives, -1)
+        r = withCards(r, b, bGives, -1)
+        r = withCards(r, b, aGives, 1)
+        return withCards(r, a, bGives, 1)
+    }
+
+    private fun applyAcceptTrade(state: CatanState, seat: Int): CatanState {
+        if (state.ck?.goodsOffer != null) return CatanCk.answerOffer(state, seat, accept = true)
+        val offer = state.pendingTrade!!
+        return state.copy(
+            phase = CatanPhase.PLAYING,
+            pendingTrade = null,
+            resources = swapCards(state.resources, offer.by, offer.give, seat, offer.get),
             log = state.log + "Seat $seat accepts — the cards cross the table.",
         )
     }
 
     private fun applyDeclineTrade(state: CatanState, seat: Int): CatanState =
-        state.copy(
+        if (state.ck?.goodsOffer != null) {
+            CatanCk.answerOffer(state, seat, accept = false)
+        } else {
+            advanceTrade(state, state.pendingTrade!!, seat, "Seat $seat declines the offer.")
+        }
+
+    private fun applyCounterTrade(state: CatanState, seat: Int, move: CounterTrade): CatanState {
+        val offer = state.pendingTrade!!
+        val counter = TradeCounter(by = seat, give = move.give, get = move.get)
+        return advanceTrade(
+            state,
+            offer.copy(counters = offer.counters + counter),
+            seat,
+            "Seat $seat counters: ${describe(countOf(move.give))} for ${describe(countOf(move.get))}.",
+        )
+    }
+
+    private fun applyAcceptCounter(state: CatanState, move: AcceptCounter): CatanState {
+        if (state.ck?.goodsOffer != null) return CatanCk.acceptCounter(state, move)
+        val offer = state.pendingTrade!!
+        val counter = offer.counters.first { it.by == move.seat }
+        return state.copy(
             phase = CatanPhase.PLAYING,
             pendingTrade = null,
-            log = state.log + "Seat $seat declines the offer.",
+            resources = swapCards(state.resources, offer.by, counter.get, counter.by, counter.give),
+            log = state.log + "Seat ${offer.by} takes seat ${counter.by}'s counter — the cards cross the table.",
+        )
+    }
+
+    private fun applyDismissCounters(state: CatanState): CatanState =
+        if (state.ck?.goodsOffer != null) CatanCk.dismissCounters(state) else state.copy(
+            phase = CatanPhase.PLAYING,
+            pendingTrade = null,
+            log = state.log + "Seat ${state.turn} turns the counter-offers down.",
         )
 
     private fun applyMaritimeTrade(state: CatanState, seat: Int, move: MaritimeTrade): CatanState {
@@ -668,8 +814,8 @@ object CatanRules : GameRules<CatanState, CatanMove> {
         val s = state.copy(resources = withCards(paid, seat, listOf(move.get), 1))
         val via = if (ratio == 4) "the bank" else "a $ratio:1 harbour"
         return s.copy(
-            log = s.log + "Seat $seat trades $ratio ${move.give.name.lowercase()} for a " +
-                "${move.get.name.lowercase()} via $via.",
+            log = s.log + ("Seat $seat trades $ratio ${move.give.name.lowercase()} for a " +
+                "${move.get.name.lowercase()} via $via."),
         )
     }
 
@@ -679,7 +825,7 @@ object CatanRules : GameRules<CatanState, CatanMove> {
         if (settled.phase == CatanPhase.GAME_OVER) return settled
 
         val next = (state.turn + 1) % state.playerCount
-        val s = state.copy(
+        val s = (if (state.isCk) CatanCk.endTurn(state) else state).copy(
             turn = next,
             turnNumber = state.turnNumber + 1,
             phase = CatanPhase.AWAIT_ROLL,
@@ -692,9 +838,13 @@ object CatanRules : GameRules<CatanState, CatanMove> {
         return checkWin(s)
     }
 
+    /** Where play goes after free roads: a card played before the roll returns to the roll. */
+    private fun phaseAfterRoads(state: CatanState): CatanPhase =
+        if (state.ck?.back == Back.AWAIT_ROLL) CatanPhase.AWAIT_ROLL else CatanPhase.PLAYING
+
     private fun applyEndFreeRoads(state: CatanState, seat: Int): CatanState =
         state.copy(
-            phase = CatanPhase.PLAYING,
+            phase = phaseAfterRoads(state),
             pendingFreeRoads = 0,
             log = state.log + "Seat $seat forfeits the remaining free road.",
         )
@@ -710,6 +860,7 @@ object CatanRules : GameRules<CatanState, CatanMove> {
      * view or the host's copy.
      */
     fun publicVictoryPoints(state: CatanState): List<Int> {
+        if (state.isCk) return CatanCk.publicVictoryPoints(state)
         val points = IntArray(state.playerCount)
         state.buildings.forEach { building ->
             if (building != null) {
@@ -725,7 +876,7 @@ object CatanRules : GameRules<CatanState, CatanMove> {
         publicVictoryPoints(state)[seat] +
             state.devHands[seat].count { it.type == DevCardType.VICTORY_POINT }
 
-    private fun checkWin(state: CatanState): CatanState {
+    internal fun checkWin(state: CatanState): CatanState {
         if (state.phase == CatanPhase.GAME_OVER) return state
         val seat = state.turn
         val points = victoryPoints(state, seat)
@@ -746,7 +897,7 @@ object CatanRules : GameRules<CatanState, CatanMove> {
      * road falls below five segments the award reopens to the longest road
      * of five or more, lowest seat first on a tie.
      */
-    private fun refreshLongestRoad(state: CatanState): CatanState {
+    internal fun refreshLongestRoad(state: CatanState): CatanState {
         val lengths = (0 until state.playerCount).map { longestRoadFor(state, it) }
         val holder = state.longestRoadOwner
         val best = lengths
@@ -782,6 +933,7 @@ object CatanRules : GameRules<CatanState, CatanMove> {
             val building = state.buildings[v]
             if (building != null && building.owner != seat) blocked[v] = true
         }
+        state.ck?.knights?.forEach { if (it.owner != seat) blocked[it.vertex] = true }
         for (start in 0 until CatanBoard.VERTEX_COUNT) {
             if (CatanBoard.VERTEX_EDGES[start].none { state.roads[it] == seat }) continue
             val visited = BooleanArray(CatanBoard.VERTEX_COUNT)
@@ -843,7 +995,7 @@ object CatanRules : GameRules<CatanState, CatanMove> {
     fun bankSupply(state: CatanState, resource: Resource): Int =
         BANK_PER_RESOURCE - state.resources.sumOf { it[resource] ?: 0 }
 
-    private fun affordable(state: CatanState, seat: Int, cost: Map<Resource, Int>): Boolean =
+    internal fun affordable(state: CatanState, seat: Int, cost: Map<Resource, Int>): Boolean =
         cost.all { (resource, need) -> (state.resources[seat][resource] ?: 0) >= need }
 
     private fun payCost(state: CatanState, seat: Int, cost: Map<Resource, Int>): CatanState =
@@ -894,6 +1046,16 @@ object CatanRules : GameRules<CatanState, CatanMove> {
         return best
     }
 
+    /** 3 if [seat] has a settlement on a generic harbour, else the bank's 4. */
+    fun genericPortRatio(state: CatanState, seat: Int): Int {
+        for (port in state.ports) {
+            if (port.resource != null) continue
+            val (a, b) = CatanBoard.EDGE_VERTICES[port.edge]
+            if (state.buildings[a]?.owner == seat || state.buildings[b]?.owner == seat) return port.ratio
+        }
+        return 4
+    }
+
     // -----------------------------------------------------------------------
     // Results, redaction and wire format
     // -----------------------------------------------------------------------
@@ -908,12 +1070,15 @@ object CatanRules : GameRules<CatanState, CatanMove> {
         else -> "Seat $winner wins"
     }
 
-    override fun viewFor(state: CatanState, seat: Int): CatanState = state.copy(
-        // Hidden information stays with the holder and the host.
-        devDeck = emptyList(),
-        devHands = state.devHands.mapIndexed { index, hand ->
-            if (index == seat) hand else emptyList()
-        },
+    override fun viewFor(state: CatanState, seat: Int): CatanState = CatanCk.viewFor(
+        state.copy(
+            // Hidden information stays with the holder and the host.
+            devDeck = emptyList(),
+            devHands = state.devHands.mapIndexed { index, hand ->
+                if (index == seat) hand else emptyList()
+            },
+        ),
+        seat,
     )
 
     override fun encodeState(state: CatanState): String = json.encodeToString(state)

app/src/main/java/org/prolibertate/games/game/engine/SavedGame.kt

@@ -0,0 +1,101 @@
+package org.prolibertate.games.game.engine
+
+import kotlinx.serialization.Serializable
+import kotlinx.serialization.json.Json
+import java.io.File
+
+/**
+ * A game in progress, kept so it can be picked up again after the app has been
+ * closed.
+ *
+ * The match is stored the way the host holds it: the [config] it was dealt from
+ * (seed, seats, options) and the whole authoritative [stateJson], hidden cards
+ * included, as the game's own rules encode it. Nothing here knows what game it
+ * is; [gameId] is only the name of the slot.
+ */
+@Serializable
+data class SavedMatch(
+    val gameId: String,
+    val config: TableConfig,
+    /** The seat the person at this device plays. */
+    val localSeat: Int,
+    val stateJson: String,
+    /** Wall-clock milliseconds when the position was written. */
+    val savedAtMillis: Long,
+    /** A line saying how the game stands, from the rules' own summary. */
+    val summary: String = "",
+)
+
+/**
+ * One saved game per game, kept as a file each under [directory].
+ *
+ * One slot per game rather than a list: the player is mid-way through a game of
+ * Chess or they are not. Starting a new one replaces it, which is what the
+ * resume prompt on the setup screen says.
+ *
+ * Writes are atomic — the position goes to a temporary file that is then moved
+ * over the real one — so being killed half way through a save leaves the
+ * previous position, not half of the new one. Reads never throw: a file that
+ * will not parse is a game that cannot be resumed, so it is removed and reported
+ * as absent.
+ */
+class SavedGameStore(private val directory: File) {
+
+    private val json = Json {
+        ignoreUnknownKeys = true
+        encodeDefaults = true
+    }
+
+    private fun fileFor(gameId: String): File {
+        // The ids are catalogue constants, but they become file names, so
+        // nothing that could climb out of the directory is let through.
+        require(gameId.isNotBlank() && gameId.all { it.isLetterOrDigit() || it == '_' || it == '-' }) {
+            "Not a game id: $gameId"
+        }
+        return File(directory, "$gameId.json")
+    }
+
+    /** Writes [match] over whatever was saved for its game. */
+    @Synchronized
+    fun save(match: SavedMatch) {
+        directory.mkdirs()
+        val target = fileFor(match.gameId)
+        val temp = File(directory, "${match.gameId}.json.tmp")
+        temp.writeText(json.encodeToString(SavedMatch.serializer(), match))
+        if (!temp.renameTo(target)) {
+            // Some file systems will not rename over an existing file.
+            target.delete()
+            check(temp.renameTo(target)) { "Could not write the saved game" }
+        }
+    }
+
+    /** The saved game for [gameId], or null if there is none or it cannot be read. */
+    @Synchronized
+    fun load(gameId: String): SavedMatch? {
+        val file = fileFor(gameId)
+        if (!file.isFile) return null
+        val match = runCatching {
+            json.decodeFromString(SavedMatch.serializer(), file.readText())
+        }.getOrNull()
+        if (match == null || match.gameId != gameId) {
+            file.delete()
+            return null
+        }
+        return match
+    }
+
+    /** Forgets the saved game for [gameId]. A no-op if there is none. */
+    @Synchronized
+    fun clear(gameId: String) {
+        fileFor(gameId).delete()
+    }
+
+    /** Every readable saved game, the most recently played first. */
+    @Synchronized
+    fun all(): List<SavedMatch> {
+        val files = directory.listFiles { f -> f.isFile && f.name.endsWith(".json") } ?: return emptyList()
+        return files
+            .mapNotNull { file -> runCatching { load(file.name.removeSuffix(".json")) }.getOrNull() }
+            .sortedByDescending { it.savedAtMillis }
+    }
+}

app/src/main/java/org/prolibertate/games/game/meowdoku/MeowdokuAi.kt

@@ -0,0 +1,39 @@
+package org.prolibertate.games.game.meowdoku
+
+import org.prolibertate.games.game.engine.GameAi
+
+/**
+ * Plays the board for the one seat.
+ *
+ * Like peg solitaire's AI, nothing normally asks it to: the single seat belongs
+ * to the person holding the phone. It exists because an empty seat has to be
+ * playable by something, and because "the computer can finish this board" is a
+ * property worth testing — a generated puzzle that only a human could unpack is
+ * a broken promise about uniqueness.
+ *
+ * It reads the answer from the state. The rules hold it, the seat is alone with
+ * it, and a solver that deduced its way there would be the same length as the
+ * hint engine in the original game without making this seat any more honest.
+ */
+object MeowdokuAi : GameAi<MeowdokuState, MeowdokuMove> {
+
+    override fun chooseMove(
+        state: MeowdokuState,
+        seat: Int,
+        legal: List<MeowdokuMove>,
+    ): MeowdokuMove {
+        require(legal.isNotEmpty()) { "No move available" }
+        val places = legal.filterIsInstance<PlaceCat>().associateBy { it.square }
+
+        // The first cat still missing. A cross on its square is no obstacle:
+        // crossed squares take attempts like anything else, and a correct one
+        // replaces the cross.
+        for (row in 0 until state.side) {
+            if (state.cats.none { it.row == row }) {
+                places[Square(row, state.catCols[row])]?.let { return it }
+            }
+        }
+
+        return legal.first()
+    }
+}

app/src/main/java/org/prolibertate/games/game/meowdoku/MeowdokuGenerator.kt

@@ -0,0 +1,371 @@
+package org.prolibertate.games.game.meowdoku
+
+import kotlin.math.abs
+
+/**
+ * Builds the puzzles.
+ *
+ * A Meowdoku puzzle is an N by N board, a colouring of it into N regions, and a
+ * hidden answer of N cats. The three are not chosen separately: the cats come
+ * first, then the regions grow out from them so every region owns exactly one
+ * cat, then the finished board is checked to make sure it has only that one
+ * answer. A puzzle with two answers is a puzzle with no answer, since the second
+ * one cannot be deduced from what is printed.
+ *
+ * The construction is seeded and reproducible: the same seed gives the same
+ * board, which is what lets a saved game come back unchanged and lets a test
+ * speak about "the" puzzle for a seed.
+ */
+object MeowdokuGenerator {
+
+    /** Smallest and largest boards worth dealing; anything bigger is a wall. */
+    val MIN_SIDE = 4
+    val MAX_SIDE = 10
+
+    /**
+     * The answer, as the column of the cat in each row.
+     *
+     * One cat per row and one per column is already built in, since the rows are
+     * enumerated once each and no column is taken twice.
+     */
+    fun placeCats(side: Int, rng: SeededRng): IntArray {
+        val cols = IntArray(side) { -1 }
+        val placed = placeCatsFrom(0, side, cols, rng)
+        // Every board from four up has a placement, and the search is complete,
+        // so failing here would mean the generator itself is broken.
+        check(placed) { "No way to settle $side cats on a $side board" }
+        return cols
+    }
+
+    private fun placeCatsFrom(row: Int, side: Int, cols: IntArray, rng: SeededRng): Boolean {
+        if (row == side) return true
+        for (col in rng.shuffled(cols.indices.toList())) {
+            if (catFitsHere(row, col, cols)) {
+                cols[row] = col
+                if (placeCatsFrom(row + 1, side, cols, rng)) return true
+                cols[row] = -1
+            }
+        }
+        return false
+    }
+
+    /**
+     * Whether a cat at [row],[col] is at peace with the cats in the rows above.
+     *
+     * No shared column, and no shared corner: a cat grooms the squares touching
+     * its own on all eight sides, so a neighbour one step away in any direction
+     * is too close.
+     */
+    fun catFitsHere(row: Int, col: Int, cols: IntArray): Boolean {
+        for (r in 0 until row) {
+            val c = cols[r]
+            if (c == col) return false
+            if (abs(r - row) <= 1 && abs(c - col) <= 1) return false
+        }
+        return true
+    }
+
+    /**
+     * The colours of the board, as a region id per square.
+     *
+     * Each region starts as the cat it contains and grows outwards one square at
+     * a time. The first [strips] regions are grown as straight bars along their
+     * cat's row or column, alternating which way they run: a board of nothing but
+     * blobs reads as texture, and the bars are what give the regions a shape a
+     * player can reason about. The rest take the shortest border square, which
+     * keeps them clumped rather than trailing off into the far corner.
+     */
+    fun growRegions(side: Int, catCols: IntArray, rng: SeededRng, strips: Int): Array<IntArray> {
+        val regions = Array(side) { IntArray(side) { -1 } }
+        val dirs = listOf(0 to 1, 0 to -1, 1 to 0, -1 to 0)
+
+        // Region i owns the cat in row i, which is where its colour starts.
+        for (r in 0 until side) regions[r][catCols[r]] = r
+
+        val sizes = IntArray(side) { 1 }
+        var unassigned = side * side - side
+
+        // The straight bars are laid first, and the rest is grown around them.
+        // The straight bars are laid first, and the rest is grown around them.
+        // Bar i runs along its cat's row when i is even, down its column when odd.
+        val stripRegions = rng.shuffled((0 until side).toList()).take(strips.coerceIn(0, side - 1)).toSet()
+        for ((n, region) in stripRegions.withIndex()) {
+            val r0 = region
+            val c0 = catCols[r0]
+            val extra = 1 + rng.nextInt(3)
+            var added = 0
+            if (n % 2 == 0) {
+                var left = c0 - 1
+                var right = c0 + 1
+                while (added < extra) {
+                    val goLeft = rng.nextBoolean()
+                    when {
+                        goLeft && left >= 0 && regions[r0][left] == -1 ->
+                            regions[r0][left--] = region
+                        right < side && regions[r0][right] == -1 ->
+                            regions[r0][right++] = region
+                        left >= 0 && regions[r0][left] == -1 ->
+                            regions[r0][left--] = region
+                        else -> break
+                    }
+                    sizes[region]++
+                    unassigned--
+                    added++
+                }
+            } else {
+                var up = r0 - 1
+                var down = r0 + 1
+                while (added < extra) {
+                    val goUp = rng.nextBoolean()
+                    when {
+                        goUp && up >= 0 && regions[up][c0] == -1 ->
+                            regions[up--][c0] = region
+                        down < side && regions[down][c0] == -1 ->
+                            regions[down++][c0] = region
+                        up >= 0 && regions[up][c0] == -1 ->
+                            regions[up--][c0] = region
+                        else -> break
+                    }
+                    sizes[region]++
+                    unassigned--
+                    added++
+                }
+            }
+        }
+
+        // What is left goes to whichever neighbouring region is smallest, so no
+        // region dies young while another sprawls.
+        var guard = side * side * 20
+        while (unassigned > 0 && guard > 0) {
+            guard--
+            for (r in 0 until side) {
+                for (c in 0 until side) {
+                    if (regions[r][c] != -1) continue
+                    var best = -1
+                    for ((dr, dc) in dirs) {
+                        val nr = r + dr
+                        val nc = c + dc
+                        if (nr !in 0 until side || nc !in 0 until side) continue
+                        val neighbour = regions[nr][nc]
+                        if (neighbour == -1 || neighbour in stripRegions) continue
+                        if (best == -1 || sizes[neighbour] < sizes[best]) best = neighbour
+                    }
+                    if (best == -1) {
+                        for ((dr, dc) in dirs) {
+                            val nr = r + dr
+                            val nc = c + dc
+                            if (nr !in 0 until side || nc !in 0 until side) continue
+                            val neighbour = regions[nr][nc]
+                            if (neighbour != -1 && (best == -1 || sizes[neighbour] < sizes[best])) {
+                                best = neighbour
+                            }
+                        }
+                    }
+                    if (best != -1) {
+                        regions[r][c] = best
+                        sizes[best]++
+                        unassigned--
+                    }
+                }
+            }
+        }
+        for (r in 0 until side) {
+            for (c in 0 until side) {
+                if (regions[r][c] == -1) regions[r][c] = 0
+            }
+        }
+        return regions
+    }
+
+    /**
+     * How many answers this coloured board has, up to [limit].
+     *
+     * A depth-first search with the obvious propagation: once a row is given a
+     * cat, the squares that cat excludes — its column, the rows beside it, and
+     * everything in its colour — lose their candidates. A row whose candidate
+     * list runs out fails immediately and the search backtracks, which is what
+     * makes the count finish quickly on boards of this size.
+     *
+     * Nothing about the true cats is handed to the search; it sees the colours
+     * and the rules and no more.
+     */
+    fun countSolutions(side: Int, regions: Array<IntArray>, limit: Int = 2): Int {
+        val candidates = Array(side) { r -> (0 until side).toMutableSet() }
+        val colsTaken = BooleanArray(side)
+        val coloursTaken = BooleanArray(side)
+        val count = IntArray(1)
+        solve(0, side, regions, candidates, colsTaken, coloursTaken, count, limit)
+        return count[0]
+    }
+
+    private fun solve(
+        row: Int,
+        side: Int,
+        regions: Array<IntArray>,
+        candidates: Array<MutableSet<Int>>,
+        colsTaken: BooleanArray,
+        coloursTaken: BooleanArray,
+        count: IntArray,
+        limit: Int,
+    ) {
+        if (count[0] >= limit) return
+        if (row == side) {
+            count[0]++
+            return
+        }
+        for (col in candidates[row].toList()) {
+            val colour = regions[row][col]
+            if (colsTaken[col] || coloursTaken[colour]) continue
+            val undo = exclude(row, col, side, regions, candidates)
+            if (undo != null) {
+                colsTaken[col] = true
+                coloursTaken[colour] = true
+                solve(row + 1, side, regions, candidates, colsTaken, coloursTaken, count, limit)
+                colsTaken[col] = false
+                coloursTaken[colour] = false
+                undo()
+            }
+            if (count[0] >= limit) return
+        }
+    }
+
+    /**
+     * Crosses out what the cat at [row],[col] forbids, and returns the function
+     * that puts it back. Returns null if some row loses its last candidate,
+     * which means this placement is a dead end.
+     */
+    private fun exclude(
+        row: Int,
+        col: Int,
+        side: Int,
+        regions: Array<IntArray>,
+        candidates: Array<MutableSet<Int>>,
+    ): (() -> Unit)? {
+        val colour = regions[row][col]
+        val saved = Array(side) { r -> candidates[r].toMutableSet() }
+        var dead = false
+        for (r in 0 until side) {
+            if (r == row) continue
+            candidates[r].remove(col)
+            if (abs(r - row) == 1) {
+                candidates[r].remove(col - 1)
+                candidates[r].remove(col + 1)
+            }
+            candidates[r].removeAll { c -> regions[r][c] == colour }
+            if (candidates[r].isEmpty()) dead = true
+        }
+        if (dead) {
+            for (r in 0 until side) candidates[r] = saved[r]
+            return null
+        }
+        return {
+            for (r in 0 until side) candidates[r] = saved[r]
+        }
+    }
+
+    /**
+     * A complete puzzle: the colours, the answer, and a proof it is unique.
+     *
+     * Generation is rejection rather than construction — build a board, check it,
+     * throw it away if the check fails — and the attempts walk forward from
+     * [seed] so a seed that has a puzzle within a few tries gives the same one
+     * every time.
+     */
+    fun generate(side: Int, seed: Long): MeowdokuPuzzle? {
+        val base = (seed xor (seed ushr 32)).toInt()
+        for (attempt in 0 until MAX_ATTEMPTS) {
+            val rng = SeededRng(base + attempt * 7919)
+            val catCols = placeCats(side, rng)
+            val regions = growRegions(side, catCols, SeededRng(base * 31 + attempt * 104729), strips = side / 2)
+            if (distinctColours(side, regions) != side) continue
+            if (countSolutions(side, regions, limit = 2) != 1) continue
+            return MeowdokuPuzzle(side, regions, catCols)
+        }
+        return null
+    }
+
+    private const val MAX_ATTEMPTS = 4000
+
+    /** How many different colours a board actually shows. */
+    private fun distinctColours(side: Int, regions: Array<IntArray>): Int =
+        regions.flatMap { it.toList() }.distinct().size
+}
+
+/**
+ * A board and its answer.
+ *
+ * The answer is stored rather than re-derived because the rules need it to
+ * referee: a tap either lands a cat or loses a heart, and that is judged against
+ * the solution, not against whether the player could have deduced it.
+ */
+data class MeowdokuPuzzle(
+    val side: Int,
+    /** Region id per square; ids run 0 until side. */
+    val regions: Array<IntArray>,
+    /** The column of the cat in each row. */
+    val catCols: IntArray,
+) {
+    fun regionOf(row: Int, col: Int): Int = regions[row][col]
+
+    /** Every colour id, in board order, for a legend or a palette. */
+    val colours: List<Int> get() = (0 until side).toList()
+
+    fun solutionSquares(): List<Pair<Int, Int>> =
+        catCols.indices.map { it to catCols[it] }
+
+    override fun equals(other: Any?): Boolean = other is MeowdokuPuzzle &&
+        side == other.side &&
+        regions.contentDeepEquals(other.regions) &&
+        catCols.contentEquals(other.catCols)
+
+    override fun hashCode(): Int = 31 * side + regions.contentDeepHashCode()
+}
+
+/**
+ * A 32-bit linear congruential generator.
+ *
+ * Deliberately not [kotlin.random.Random]: that one is seeded per-JVM and can
+ * change between releases, and a puzzle generator that drifts silently corrupts
+ * saved games. This one is small, explicit, and the same everywhere.
+ */
+class SeededRng(seed: Int) {
+    private var state = if (seed == 0) DEFAULT_SEED else seed
+
+    /** The next 31 bits, as a non-negative int. */
+    fun nextInt(): Int {
+        state = state * MULTIPLIER + 1
+        return (state ushr 1) and 0x7FFF_FFFF
+    }
+
+    /** A value in 0 until [bound], taken by rejection so it stays uniform. */
+    fun nextInt(bound: Int): Int {
+        require(bound > 0)
+        while (true) {
+            val n = nextInt()
+            // 2^31 is a multiple of no useful number of squares, so a bare
+            // modulus biases the low values; the slack is thrown and redrawn.
+            if (n < Int.MAX_VALUE - (Int.MAX_VALUE % bound)) return n % bound
+        }
+    }
+
+    fun nextBoolean(): Boolean = nextInt(2) == 0
+
+    /** The same list every time for the same seed, in a different order. */
+    fun <T> shuffled(items: List<T>): List<T> {
+        val out = items.toMutableList()
+        for (i in out.lastIndex downTo 1) {
+            val j = nextInt(i + 1)
+            val tmp = out[i]
+            out[i] = out[j]
+            out[j] = tmp
+        }
+        return out
+    }
+
+    private companion object {
+        // The constants of the old VAX C library's `rand`, which are well tested
+        // and give a period of the full 31 bits.
+        const val MULTIPLIER = 1103515245
+        const val DEFAULT_SEED = 0x5DEECE66D.toInt()
+    }
+}

app/src/main/java/org/prolibertate/games/game/meowdoku/MeowdokuModel.kt

@@ -0,0 +1,119 @@
+package org.prolibertate.games.game.meowdoku
+
+import kotlinx.serialization.SerialName
+import kotlinx.serialization.Serializable
+
+// Meowdoku hides N cats in an N by N board: exactly one cat in every row, every
+// column and every colour, and no two cats sharing even a corner. A tap crosses
+// a square over; a second tap on that square asks the board whether a cat
+// lives there. A right answer lands the cat, a wrong one costs a heart and
+// keeps the cross — so the crossing over is both the player's note and the
+// first half of every guess, and the hearts are what stop it being a lottery.
+
+/** One square of the board. */
+@Serializable
+data class Square(val row: Int, val col: Int)
+
+@Serializable
+data class MeowdokuOptions(
+    /** The board is [side] by [side], and the answer is [side] cats. */
+    val side: Int = 6,
+    /**
+     * How many wrong taps the board forgives. The original game deals three,
+     * and the hearts on a level are part of its difficulty rather than a
+     * courtesy.
+     */
+    val hearts: Int = 3,
+    /** How many cats the board will show on demand. */
+    val hints: Int = 3,
+) {
+    init {
+        require(side in MeowdokuGenerator.MIN_SIDE..MeowdokuGenerator.MAX_SIDE) {
+            "No board of $side squares a side"
+        }
+        require(hearts in 1..9) { "A board with no hearts is lost before it is dealt" }
+        require(hints in 0..9) { "Hints must read on the board, not scroll" }
+    }
+}
+
+/**
+ * The dealt board plus the marks on it.
+ *
+ * [cats] and [marks] are sets rather than a state per square because a square's
+ * story is exactly those two memberships: nothing is a cat and crossed, and the
+ * empty squares carry no information worth storing.
+ */
+@Serializable
+data class MeowdokuState(
+    val options: MeowdokuOptions,
+    /** The region id of every square, row by row. Ids run 0 until [side]. */
+    val regions: List<List<Int>>,
+    /** The column of the cat in each row — the answer, kept so taps can be judged. */
+    val catCols: List<Int>,
+    /** Cats the player has found (or a hint has shown). */
+    val cats: Set<Square>,
+    /** Squares crossed over: wrong taps and pencil marks alike. */
+    val marks: Set<Square>,
+    val heartsLeft: Int,
+    val hintsLeft: Int,
+    /** Wrong taps so far, which is how a solved board says how it was solved. */
+    val wrongCats: Int,
+    /** The last square touched, and whether touching it cost a heart. */
+    val lastSquare: Square? = null,
+    val lastWrong: Boolean = false,
+    val log: List<String>,
+) {
+    val side: Int get() = options.side
+
+    /** Cats found, out of the [side] the board hides. */
+    val catsFound: Int get() = cats.size
+
+    val solved: Boolean get() = catsFound == side
+
+    /** Out of hearts, with cats still missing. */
+    val lost: Boolean get() = heartsLeft == 0 && !solved
+
+    fun regionOf(square: Square): Int = regions[square.row][square.col]
+
+    fun isCatSquare(square: Square): Boolean = catCols[square.row] == square.col
+}
+
+/** What the player may do to a board. */
+@Serializable
+sealed interface MeowdokuMove
+
+/**
+ * The second tap of a double tap: the cat attempt.
+ *
+ * One move rather than two, because that is what the player is doing: the board
+ * decides whether the tap found a cat or cost a heart. The square may carry the
+ * cross its own first tap just drew — that cross is part of the double tap,
+ * not a decision against it — and a correct attempt replaces it.
+ */
+@Serializable
+@SerialName("cat")
+data class PlaceCat(val square: Square) : MeowdokuMove
+
+/**
+ * Draws or erases a cross on a square with no cat on it.
+ *
+ * This is the first tap of a tap pair and every cell of a drag stroke, so it is
+ * the note-taking half of the scheme: free, unrewarded, and the board cannot
+ * lose a heart over it. A cross drawn here can still be tapped through with a
+ * cat attempt — the note is the player's, and only they get to change their
+ * mind about it.
+ */
+@Serializable
+@SerialName("pencil")
+data class TogglePencil(val square: Square) : MeowdokuMove
+
+/**
+ * Spends a hint to show the cat in the first row that lacks one.
+ *
+ * The original game sells hints; here they are simply counted, and the one
+ * choice that has to be made about them — a hint is placed by the board, not
+ * guessed at by the player — is the same either way.
+ */
+@Serializable
+@SerialName("hint")
+data object TakeHint : MeowdokuMove

app/src/main/java/org/prolibertate/games/game/meowdoku/MeowdokuRules.kt

@@ -0,0 +1,197 @@
+package org.prolibertate.games.game.meowdoku
+
+import kotlinx.serialization.encodeToString
+import kotlinx.serialization.json.Json
+import org.prolibertate.games.game.GameCatalog
+import org.prolibertate.games.game.engine.GameRules
+import org.prolibertate.games.game.engine.TableConfig
+
+/**
+ * Meowdoku as a pure state machine. See RULES-meowdoku.md.
+ *
+ * The engine is a second single-seat game, alongside peg solitaire, and it
+ * inherits the same freedom: there is nobody to hide anything from, so
+ * [viewFor] hands out the whole board including the answer. The answer lives in
+ * the state rather than being re-derived because judging a tap against a
+ * deduction the player could have made is a different thing from judging it
+ * against what the board was dealt — and the deduction engine (crossing out
+ * rows, columns and colours) belongs to the player, not the referee.
+ */
+object MeowdokuRules : GameRules<MeowdokuState, MeowdokuMove> {
+
+    override val gameId: String = GameCatalog.MEOWDOKU
+
+    /** The one seat. */
+    const val SOLO_SEAT: Int = 0
+
+    private val json = Json {
+        ignoreUnknownKeys = true
+        encodeDefaults = true
+    }
+
+    override fun initialState(config: TableConfig): MeowdokuState {
+        val options = json.decodeFromString<MeowdokuOptions>(config.optionsJson)
+        require(config.seats.size == 1) {
+            "Meowdoku seats one, not ${config.seats.size}"
+        }
+        val puzzle = deal(options.side, config.seed)
+        return MeowdokuState(
+            options = options,
+            regions = puzzle.regions.map { it.toList() },
+            catCols = puzzle.catCols.toList(),
+            cats = emptySet(),
+            marks = emptySet(),
+            heartsLeft = options.hearts,
+            hintsLeft = options.hints,
+            wrongCats = 0,
+            log = listOf("A ${options.side} by ${options.side} board, ${options.side} cats to find."),
+        )
+    }
+
+    /**
+     * Deals until the board is good.
+     *
+     * A seed whose first attempts all fail to produce a unique board moves the
+     * seed along rather than giving up: the same table asked twice gets the
+     * same board both times, which is what a saved game and a unit test need.
+     */
+    private fun deal(side: Int, seed: Long): MeowdokuPuzzle {
+        var trySeed = seed
+        repeat(DEAL_TRIES) {
+            MeowdokuGenerator.generate(side, trySeed)?.let { return it }
+            trySeed = trySeed * 6364136223846793005L + 1442695040888963407L
+        }
+        error("No unique ${side} x $side board within $DEAL_TRIES deals of seed $seed")
+    }
+
+    private const val DEAL_TRIES = 8
+
+    /**
+     * Every tap the board would take.
+     *
+     * The scheme is the original's: the first tap crosses a square over and
+     * opens a short window, and a second tap in that window is the cat attempt
+     * — so an attempt is offered on every square without a cat, crossed or
+     * not. The cross the attempt replaces is exactly the cross the first tap
+     * drew. Cats, once placed, are never tapped again: they are not a guess
+     * you take back.
+     *
+     * The list is written row by row, which is also the order the hint uses.
+     */
+    override fun legalMoves(state: MeowdokuState, seat: Int): List<MeowdokuMove> {
+        if (seat != SOLO_SEAT || isFinished(state)) return emptyList()
+        val cats = ArrayList<MeowdokuMove>()
+        val pencils = ArrayList<MeowdokuMove>()
+        for (row in 0 until state.side) {
+            for (col in 0 until state.side) {
+                val square = Square(row, col)
+                if (square in state.cats) continue
+                cats += PlaceCat(square)
+                pencils += TogglePencil(square)
+            }
+        }
+        val hint = if (state.hintsLeft > 0) listOf(TakeHint) else emptyList()
+        return cats + pencils + hint
+    }
+
+    override fun applyMove(
+        state: MeowdokuState,
+        seat: Int,
+        move: MeowdokuMove,
+    ): MeowdokuState {
+        require(seat == SOLO_SEAT) { "Meowdoku has one seat" }
+        require(move in legalMoves(state, seat)) { "$move is not a legal move" }
+        return when (move) {
+            is PlaceCat -> tap(state, move.square)
+            is TogglePencil -> pencil(state, move.square)
+            TakeHint -> hint(state)
+        }
+    }
+
+    /**
+     * The second tap of a double tap: found a cat, or lost a heart.
+     *
+     * A correct tap clears the cross the first tap left behind — the cat
+     * replaces it. A wrong one leaves the cross where it is and spends a
+     * heart, because a wrong square crossed twice is the same mistake twice,
+     * and the board remembers it either way.
+     */
+    private fun tap(state: MeowdokuState, square: Square): MeowdokuState {
+        if (state.isCatSquare(square)) {
+            val next = state.copy(
+                cats = state.cats + square,
+                marks = state.marks - square,
+                lastSquare = square,
+                lastWrong = false,
+            )
+            val note = if (next.solved) {
+                "All ${next.side} cats, ${next.wrongCats} wrong taps."
+            } else {
+                "Found a cat at row ${square.row + 1}, column ${square.col + 1}."
+            }
+            return next.copy(log = next.log + note)
+        }
+        val hearts = state.heartsLeft - 1
+        val next = state.copy(
+            marks = state.marks + square,
+            heartsLeft = hearts,
+            wrongCats = state.wrongCats + 1,
+            lastSquare = square,
+            lastWrong = true,
+        )
+        return if (hearts == 0) {
+            next.copy(log = next.log + "Out of hearts, with ${next.side - next.catsFound} cats still hiding.")
+        } else {
+            next
+        }
+    }
+
+    private fun pencil(state: MeowdokuState, square: Square): MeowdokuState {
+        val marks = if (square in state.marks) state.marks - square else state.marks + square
+        return state.copy(marks = marks, lastSquare = square, lastWrong = false)
+    }
+
+    /**
+     * Shows the cat in the first row without one.
+     *
+     * A revealed cat lands like a found one — and erases a pencil cross on its
+     * square, because the point of a hint is that the player stops having to
+     * work out whether the board contradicts their own notes.
+     */
+    private fun hint(state: MeowdokuState): MeowdokuState {
+        val row = (0 until state.side).first { r -> state.cats.none { it.row == r } }
+        val square = Square(row, state.catCols[row])
+        return state.copy(
+            cats = state.cats + square,
+            marks = state.marks - square,
+            hintsLeft = state.hintsLeft - 1,
+            lastSquare = square,
+            lastWrong = false,
+            log = state.log + "A hint shows the cat in row ${row + 1}.",
+        )
+    }
+
+    /** A board is finished when it is solved or when the hearts run out. */
+    override fun isFinished(state: MeowdokuState): Boolean = state.solved || state.lost
+
+    override fun currentSeat(state: MeowdokuState): Int? =
+        if (isFinished(state)) null else SOLO_SEAT
+
+    override fun summary(state: MeowdokuState): String = when {
+        state.solved -> "Solved with ${state.heartsLeft} hearts to spare"
+        state.lost -> "Lost with ${state.catsFound} of ${state.side} cats found"
+        else -> "${state.catsFound} of ${state.side} cats, ${state.heartsLeft} hearts left"
+    }
+
+    /**
+     * Nothing to strip. One person plays, and the answer in the state is there
+     * for the referee, not as a secret. Should a second seat ever race through
+     * the same board, this is where [MeowdokuState.catCols] gets hidden.
+     */
+    override fun viewFor(state: MeowdokuState, seat: Int): MeowdokuState = state
+
+    override fun encodeState(state: MeowdokuState): String = json.encodeToString(state)
+    override fun decodeState(json: String): MeowdokuState = this.json.decodeFromString(json)
+    override fun encodeMove(move: MeowdokuMove): String = json.encodeToString(move)
+    override fun decodeMove(json: String): MeowdokuMove = this.json.decodeFromString(json)
+}

app/src/main/java/org/prolibertate/games/game/yahtzee/YahtzeeStats.kt

@@ -0,0 +1,58 @@
+package org.prolibertate.games.game.yahtzee
+
+import kotlinx.serialization.Serializable
+
+/** What one finished game says about the local player's card. */
+@Serializable
+data class YahtzeeRecord(
+    val total: Int,
+    val gotBonus: Boolean,
+    /** Yahtzees scored, counting the extra ones that earned the hundred. */
+    val yahtzees: Int,
+    /** Boxes written in as nothing. */
+    val zeros: Int,
+    val players: Int,
+    val won: Boolean,
+)
+
+/** Builds the record of [seat]'s card in a finished game. Ties for first count as a win. */
+fun recordOf(state: YahtzeeState, seat: Int): YahtzeeRecord {
+    val card = state.cards[seat]
+    val mine = state.totalFor(seat)
+    val best = state.cards.indices.maxOf { state.totalFor(it) }
+    return YahtzeeRecord(
+        total = mine,
+        gotBonus = card.upperBonus > 0,
+        yahtzees = (if (card[YahtzeeCategory.YAHTZEE] == YAHTZEE_SCORE) 1 else 0) +
+            state.yahtzeeBonuses[seat] / YAHTZEE_BONUS,
+        zeros = card.boxes.count { it == 0 },
+        players = state.cards.size,
+        won = mine >= best,
+    )
+}
+
+/** A game set against the ones before it. [rank] is 1 for a new best. */
+data class YahtzeeComparison(
+    val current: YahtzeeRecord,
+    val previousGames: Int,
+    val bestBefore: Int?,
+    val averageBefore: Double?,
+    val rank: Int,
+    val gamesRanked: Int,
+    val bonusRateBefore: Double?,
+    val yahtzeesBefore: Int,
+    val winRateBefore: Double?,
+)
+
+fun compareToHistory(previous: List<YahtzeeRecord>, current: YahtzeeRecord): YahtzeeComparison =
+    YahtzeeComparison(
+        current = current,
+        previousGames = previous.size,
+        bestBefore = previous.maxOfOrNull { it.total },
+        averageBefore = previous.takeIf { it.isNotEmpty() }?.map { it.total }?.average(),
+        rank = 1 + previous.count { it.total > current.total },
+        gamesRanked = previous.size + 1,
+        bonusRateBefore = previous.takeIf { it.isNotEmpty() }?.let { p -> p.count { it.gotBonus }.toDouble() / p.size },
+        yahtzeesBefore = previous.sumOf { it.yahtzees },
+        winRateBefore = previous.takeIf { it.isNotEmpty() }?.let { p -> p.count { it.won }.toDouble() / p.size },
+    )

app/src/main/java/org/prolibertate/games/net/MatchController.kt

@@ -96,6 +96,27 @@ class MatchController<S : Any, M : Any>(
 
     /** Host only: the true state. Clients never see this. */
     private var authoritative: S? = null
+
+    /** A position to carry on from instead of dealing, set by [restore] before [startAsHost]. */
+    private var restored: S? = null
+
+    /**
+     * Host only: told about every position the table reaches, so it can be kept
+     * for later. Called under the table's lock, so it must return quickly — the
+     * snapshot encodes its state only when asked, and the work of writing it
+     * belongs to whoever is listening.
+     */
+    var onHostState: ((HostSnapshot) -> Unit)? = null
+
+    /** One position of the table, as handed to [onHostState]. */
+    class HostSnapshot(
+        val finished: Boolean,
+        val summary: String,
+        private val encode: () -> String,
+    ) {
+        /** The whole true state, encoded by the game's own rules. */
+        fun stateJson(): String = encode()
+    }
     private val lock = Mutex()
     private var sequence = 0
 
@@ -160,7 +181,7 @@ class MatchController<S : Any, M : Any>(
         check(role == Role.HOST) { "Not hosting" }
         clients.forEach { connection -> listenToPeer(connection) }
         scope.launch {
-            val initial = runCatching { rules.initialState(config) }.getOrElse { error ->
+            val initial = restored ?: runCatching { rules.initialState(config) }.getOrElse { error ->
                 // A table the rules will not accept is a dead end, not a reason
                 // to take the app down with it: this runs in the screen's own
                 // scope, where nothing would catch it.
@@ -175,6 +196,20 @@ class MatchController<S : Any, M : Any>(
         }
     }
 
+    /**
+     * Host: carry on from a saved position instead of dealing a new game.
+     *
+     * Call before [startAsHost]. Returns false, and changes nothing, if
+     * [stateJson] cannot be read by this version of the game — a save made by an
+     * older build, say — and the caller should deal a fresh table instead.
+     */
+    fun restore(stateJson: String): Boolean {
+        check(role == Role.HOST) { "Only a host can restore a game" }
+        val state = runCatching { rules.decodeState(stateJson) }.getOrNull() ?: return false
+        restored = state
+        return true
+    }
+
     private fun listenToPeer(connection: Connection) {
         peers[connection.peerId] = connection
         peerJobs[connection.peerId] = scope.launch {
@@ -449,6 +484,16 @@ class MatchController<S : Any, M : Any>(
         }
         _finished.value = rules.isFinished(current)
 
+        if (role == Role.HOST) {
+            onHostState?.invoke(
+                HostSnapshot(
+                    finished = rules.isFinished(current),
+                    summary = rules.summary(current),
+                    encode = { rules.encodeState(current) },
+                ),
+            )
+        }
+
         for (slot in config.seats) {
             val peerId = slot.peerId ?: continue
             val connection = peers[peerId] ?: continue

app/src/main/java/org/prolibertate/games/net/MatchSaver.kt

@@ -0,0 +1,95 @@
+package org.prolibertate.games.net
+
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.Job
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.collectLatest
+import kotlinx.coroutines.flow.filterNotNull
+import kotlinx.coroutines.launch
+import org.prolibertate.games.game.engine.SavedGameStore
+import org.prolibertate.games.game.engine.SavedMatch
+import org.prolibertate.games.game.engine.TableConfig
+
+/**
+ * Keeps the position of one table on disk as it is played.
+ *
+ * It is fed every position the host reaches ([offer]) and writes the newest one
+ * off the main thread. Positions that arrive while a write is under way are
+ * dropped in favour of the latest — a computer's turn can be several moves in a
+ * second, and only where the game stands matters. A finished game is not kept:
+ * its slot is cleared, so a won game is not offered back as one to resume.
+ *
+ * [flush] writes whatever has not been written yet, on the caller's thread. It
+ * is what makes leaving the table, or the app going to the background, safe: the
+ * background writer may not have caught up, and the process may not be given the
+ * chance to let it.
+ */
+class MatchSaver(
+    private val store: SavedGameStore,
+    private val gameId: String,
+    private val config: TableConfig,
+    private val localSeat: Int,
+    private val scope: CoroutineScope,
+    private val clock: () -> Long = System::currentTimeMillis,
+) {
+    private val latest = MutableStateFlow<MatchController.HostSnapshot?>(null)
+    private var worker: Job? = null
+    private var written: MatchController.HostSnapshot? = null
+    private var discarded = false
+
+    /** Starts the background writer. */
+    fun start() {
+        worker = scope.launch(Dispatchers.IO) {
+            latest.filterNotNull().collectLatest { write(it) }
+        }
+    }
+
+    /** Hands over the newest position. Cheap: the encoding happens on the writer. */
+    fun offer(snapshot: MatchController.HostSnapshot) {
+        latest.value = snapshot
+    }
+
+    /** Writes the newest position now if the writer has not already. */
+    fun flush() {
+        latest.value?.let { write(it) }
+    }
+
+    /** The game was ended on purpose: forget the saved position and write no more. */
+    @Synchronized
+    fun discard() {
+        discarded = true
+        worker?.cancel()
+        worker = null
+        runCatching { store.clear(gameId) }
+    }
+
+    fun stop() {
+        worker?.cancel()
+        worker = null
+    }
+
+    @Synchronized
+    private fun write(snapshot: MatchController.HostSnapshot) {
+        if (discarded || snapshot === written) return
+        written = snapshot
+        // Saving is a courtesy to the player: a full disk must not take the game
+        // down with it.
+        runCatching {
+            if (snapshot.finished) {
+                store.clear(gameId)
+            } else {
+                store.save(
+                    SavedMatch(
+                        gameId = gameId,
+                        config = config,
+                        localSeat = localSeat,
+                        stateJson = snapshot.stateJson(),
+                        savedAtMillis = clock(),
+                        summary = snapshot.summary,
+                    ),
+                )
+            }
+        }
+    }
+}

app/src/main/java/org/prolibertate/games/score/RecentNames.kt

@@ -0,0 +1,17 @@
+package org.prolibertate.games.score
+
+/** The short list of names offered when a column is being named. */
+object RecentNames {
+    const val LIMIT = 10
+
+    /**
+     * [name] moved to the front of [names], trimmed, with any earlier copy
+     * (compared ignoring case) dropped and the list cut to [LIMIT]. A blank name
+     * leaves the list as it was.
+     */
+    fun with(names: List<String>, name: String): List<String> {
+        val typed = name.trim()
+        if (typed.isEmpty()) return names
+        return (listOf(typed) + names.filterNot { it.equals(typed, ignoreCase = true) }).take(LIMIT)
+    }
+}

app/src/main/java/org/prolibertate/games/score/ScorekeeperRepository.kt

@@ -29,6 +29,7 @@ class ScorekeeperRepository(private val context: Context) {
 
     private object Keys {
         val SHEET = stringPreferencesKey("sheet")
+        val RECENT_NAMES = stringPreferencesKey("recent_names")
     }
 
     // Unknown keys are ignored so a sheet written by a newer build can still be
@@ -45,6 +46,24 @@ class ScorekeeperRepository(private val context: Context) {
             ?: ScoreSheet()
     }
 
+    /** The names last used on a sheet, most recent first, for the rename dialog. */
+    val recentNames: Flow<List<String>> = context.scorekeeperDataStore.data.map { prefs ->
+        prefs[Keys.RECENT_NAMES]
+            ?.let { stored ->
+                runCatching { json.decodeFromString<List<String>>(stored) }.getOrNull()
+            }
+            ?: emptyList()
+    }
+
+    suspend fun rememberName(name: String) {
+        context.scorekeeperDataStore.edit { prefs ->
+            val current = prefs[Keys.RECENT_NAMES]
+                ?.let { runCatching { json.decodeFromString<List<String>>(it) }.getOrNull() }
+                .orEmpty()
+            prefs[Keys.RECENT_NAMES] = json.encodeToString(RecentNames.with(current, name))
+        }
+    }
+
     suspend fun save(sheet: ScoreSheet) {
         context.scorekeeperDataStore.edit { it[Keys.SHEET] = json.encodeToString(sheet) }
     }

app/src/main/java/org/prolibertate/games/score/SheetOp.kt

@@ -31,8 +31,18 @@ sealed interface SheetOp {
 /** Sets a fresh sheet up for [count] players, scored by round or by tally. */
 @Serializable
 @SerialName("start")
-data class StartSheet(val count: Int, val mode: ScoringMode = ScoringMode.ROUNDS) : SheetOp {
-    override fun applyTo(sheet: ScoreSheet): ScoreSheet = ScoreSheet.of(count, mode)
+data class StartSheet(
+    val count: Int,
+    val mode: ScoringMode = ScoringMode.ROUNDS,
+    /** Names for the first seats, in order; a seat past the end stays unnamed. */
+    val names: List<String> = emptyList(),
+) : SheetOp {
+    override fun applyTo(sheet: ScoreSheet): ScoreSheet {
+        val seated = ScoreSheet.of(count, mode)
+        return seated.players.foldIndexed(seated) { index, acc, player ->
+            names.getOrNull(index)?.let { acc.renamed(player.id, it) } ?: acc
+        }
+    }
 }
 
 /** Rubs everything out. */

app/src/main/java/org/prolibertate/games/settings/SettingsRepository.kt

@@ -24,6 +24,8 @@ data class Settings(
     val soundEnabled: Boolean = true,
     val animationSpeed: Float = 1.0f,
     val checkForUpdatesOnLaunch: Boolean = true,
+    /** Multiplies the system font size across the whole app. */
+    val textScale: Float = 1.0f,
     /**
      * Exactly what the user has typed, which may be blank while they are
      * mid-edit. Nothing substitutes a default into this value: doing so meant
@@ -46,6 +48,8 @@ data class Settings(
     companion object {
         const val MIN_SPEED = 0.5f
         const val MAX_SPEED = 2.0f
+        const val MIN_TEXT_SCALE = 0.8f
+        const val MAX_TEXT_SCALE = 1.6f
         const val DEFAULT_PLAYER_NAME = "Player"
     }
 }
@@ -56,6 +60,7 @@ class SettingsRepository(private val context: Context) {
         val SOUND = booleanPreferencesKey("sound_enabled")
         val SPEED = floatPreferencesKey("animation_speed")
         val UPDATE_ON_LAUNCH = booleanPreferencesKey("check_updates_on_launch")
+        val TEXT_SCALE = floatPreferencesKey("text_scale")
         val NAME = stringPreferencesKey("player_name")
         // There is deliberately no update-channel key. The channel is a
         // property of the installed APK, not a preference — an install that
@@ -69,6 +74,8 @@ class SettingsRepository(private val context: Context) {
             soundEnabled = prefs[Keys.SOUND] ?: true,
             animationSpeed = prefs[Keys.SPEED] ?: 1.0f,
             checkForUpdatesOnLaunch = prefs[Keys.UPDATE_ON_LAUNCH] ?: true,
+            textScale = (prefs[Keys.TEXT_SCALE] ?: 1.0f)
+                .coerceIn(Settings.MIN_TEXT_SCALE, Settings.MAX_TEXT_SCALE),
             playerName = prefs[Keys.NAME] ?: "",
         )
     }
@@ -83,6 +90,12 @@ class SettingsRepository(private val context: Context) {
         }
     }
 
+    suspend fun setTextScale(scale: Float) {
+        context.dataStore.edit {
+            it[Keys.TEXT_SCALE] = scale.coerceIn(Settings.MIN_TEXT_SCALE, Settings.MAX_TEXT_SCALE)
+        }
+    }
+
     suspend fun setCheckForUpdatesOnLaunch(enabled: Boolean) {
         context.dataStore.edit { it[Keys.UPDATE_ON_LAUNCH] = enabled }
     }

app/src/main/java/org/prolibertate/games/settings/YahtzeeStatsRepository.kt

@@ -0,0 +1,42 @@
+package org.prolibertate.games.settings
+
+import android.content.Context
+import androidx.datastore.core.DataStore
+import androidx.datastore.preferences.core.Preferences
+import androidx.datastore.preferences.core.edit
+import androidx.datastore.preferences.core.stringPreferencesKey
+import androidx.datastore.preferences.preferencesDataStore
+import kotlinx.coroutines.flow.first
+import kotlinx.serialization.encodeToString
+import kotlinx.serialization.json.Json
+import org.prolibertate.games.game.yahtzee.YahtzeeComparison
+import org.prolibertate.games.game.yahtzee.YahtzeeRecord
+import org.prolibertate.games.game.yahtzee.compareToHistory
+
+private val Context.yahtzeeStatsStore: DataStore<Preferences> by preferencesDataStore(
+    name = "yahtzee_stats",
+)
+
+/** The local player's finished Yahtzee games, newest last, kept to the last [KEEP]. */
+class YahtzeeStatsRepository(private val context: Context) {
+
+    private val key = stringPreferencesKey("games")
+    private val json = Json { ignoreUnknownKeys = true }
+
+    private fun decode(stored: String?): List<YahtzeeRecord> =
+        stored?.let { runCatching { json.decodeFromString<List<YahtzeeRecord>>(it) }.getOrNull() }
+            .orEmpty()
+
+    /** Compares [record] with every earlier game, then adds it to the history. */
+    suspend fun finish(record: YahtzeeRecord): YahtzeeComparison {
+        val previous = decode(context.yahtzeeStatsStore.data.first()[key])
+        context.yahtzeeStatsStore.edit {
+            it[key] = json.encodeToString((previous + record).takeLast(KEEP))
+        }
+        return compareToHistory(previous, record)
+    }
+
+    private companion object {
+        const val KEEP = 500
+    }
+}

app/src/main/java/org/prolibertate/games/ui/AppRoot.kt

@@ -20,6 +20,8 @@ import androidx.compose.material3.Card
 import androidx.compose.material3.CardDefaults
 import androidx.compose.material3.ExperimentalMaterial3Api
 import androidx.compose.material3.MaterialTheme
+import androidx.compose.ui.platform.LocalDensity
+import androidx.compose.ui.unit.Density
 import androidx.compose.material3.OutlinedButton
 import androidx.compose.material3.Scaffold
 import androidx.compose.material3.Text
@@ -29,6 +31,8 @@ import androidx.compose.runtime.Composable
 import androidx.compose.runtime.CompositionLocalProvider
 import androidx.compose.runtime.collectAsState
 import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableIntStateOf
+import androidx.compose.runtime.produceState
 import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.remember
 import androidx.compose.runtime.setValue
@@ -47,9 +51,14 @@ import org.prolibertate.games.net.ScorekeeperSession
 import org.prolibertate.games.score.ScorekeeperRepository
 import org.prolibertate.games.settings.Settings
 import org.prolibertate.games.settings.SettingsRepository
+import org.prolibertate.games.settings.YahtzeeStatsRepository
 import org.prolibertate.games.ui.game.LocalCardSpeed
 import org.prolibertate.games.update.UpdateChannel
 import org.prolibertate.games.update.Updater
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.withContext
+import org.prolibertate.games.game.engine.SavedGameStore
+import org.prolibertate.games.game.engine.SavedMatch
 
 /** Everything the screens need, assembled once by the activity. */
 class AppEnv(
@@ -60,6 +69,9 @@ class AppEnv(
     /** The shared score sheet, for the Scorekeeper to host or join. */
     val scoreSession: ScorekeeperSession,
     val peerId: String,
+    /** Games in progress, kept between sessions. */
+    val saves: SavedGameStore,
+    val yahtzeeStats: YahtzeeStatsRepository,
 )
 
 /**
@@ -83,6 +95,8 @@ sealed interface Route {
         val config: TableConfig,
         val hosting: Boolean,
         val localSeat: Int,
+        /** A saved position to carry on from, as the game's rules encoded it; null deals a new game. */
+        val resumeState: String? = null,
     ) : Route
 }
 
@@ -129,7 +143,14 @@ fun AppRoot(env: AppEnv) {
         // Card motion reads its speed from here rather than from a parameter.
         // Every card screen animates, most of them several layers deep, and the
         // alternative was passing one unchanging number down through all of it.
-        CompositionLocalProvider(LocalCardSpeed provides settings.animationSpeed) {
+        val density = LocalDensity.current
+        val scaledDensity = remember(density, settings.textScale) {
+            Density(density.density, density.fontScale * settings.textScale)
+        }
+        CompositionLocalProvider(
+            LocalCardSpeed provides settings.animationSpeed,
+            LocalDensity provides scaledDensity,
+        ) {
             AppContent(
                 env = env,
                 settings = settings,
@@ -167,6 +188,10 @@ private fun AppContent(
             // Dev builds show the games that are not finished yet; production
             // releases list only what can actually be played.
             showComingSoon = showComingSoon,
+            saved = savedGames(env, stack),
+            onResume = { saved ->
+                push(Route.Play(saved.gameId, saved.config, true, saved.localSeat, saved.stateJson))
+            },
             onPickSection = { push(Route.Section(it)) },
             onJoinGame = { push(Route.Lobby(gameId = "", optionsJson = "{}", hosting = false)) },
             onScorekeeper = { push(Route.Scorekeeper) },
@@ -194,15 +219,30 @@ private fun AppContent(
             onBack = { pop() },
         )
 
-        is Route.Setup -> GameSetupScreen(
-            descriptor = GameCatalog.byId(route.gameId)!!,
-            playerName = settings.displayName,
-            onBack = { pop() },
-            onPlayOffline = { config, seat -> push(Route.Play(route.gameId, config, true, seat)) },
-            onHostOnline = { optionsJson ->
-                push(Route.Lobby(route.gameId, optionsJson, hosting = true))
-            },
-        )
+        is Route.Setup -> {
+            // Bumped when the saved game is thrown away, so the banner goes with it.
+            var discards by remember(route) { mutableIntStateOf(0) }
+            val saved by produceState<SavedMatch?>(null, route, discards) {
+                value = withContext(Dispatchers.IO) { env.saves.load(route.gameId) }
+            }
+            GameSetupScreen(
+                descriptor = GameCatalog.byId(route.gameId)!!,
+                playerName = settings.displayName,
+                onBack = { pop() },
+                onPlayOffline = { config, seat -> push(Route.Play(route.gameId, config, true, seat)) },
+                onHostOnline = { optionsJson ->
+                    push(Route.Lobby(route.gameId, optionsJson, hosting = true))
+                },
+                saved = saved,
+                onResume = { match ->
+                    push(Route.Play(match.gameId, match.config, true, match.localSeat, match.stateJson))
+                },
+                onDiscardSaved = {
+                    env.saves.clear(route.gameId)
+                    discards++
+                },
+            )
+        }
 
         is Route.Lobby -> LobbyScreen(
             env = env,
@@ -231,6 +271,8 @@ private fun AppContent(
 @Composable
 fun MainMenuScreen(
     showComingSoon: Boolean,
+    saved: List<SavedMatch>,
+    onResume: (SavedMatch) -> Unit,
     onPickSection: (GameMenu) -> Unit,
     onJoinGame: () -> Unit,
     onScorekeeper: () -> Unit,
@@ -280,6 +322,23 @@ fun MainMenuScreen(
                     )
                 }
 
+                // Games left half-played, most recent first, above everything
+                // else: coming back to the app is mostly coming back to one.
+                if (saved.isNotEmpty()) {
+                    Text(
+                        "Continue",
+                        style = MaterialTheme.typography.labelLarge,
+                        modifier = Modifier.fillMaxWidth(),
+                    )
+                    val now = System.currentTimeMillis()
+                    saved.forEach { match ->
+                        val title = GameCatalog.byId(match.gameId)?.title ?: match.gameId
+                        Button(onClick = { onResume(match) }, modifier = Modifier.fillMaxWidth()) {
+                            Text(savedLine(title, match, now))
+                        }
+                    }
+                }
+
                 // Below the games, and full width like them, so the column
                 // stays one column all the way down.
                 OutlinedButton(
@@ -490,3 +549,17 @@ fun PrimaryAction(text: String, enabled: Boolean = true, onClick: () -> Unit) {
         Text(text)
     }
 }
+
+/**
+ * The saved games, read off the main thread each time the menu is the screen
+ * showing — which is when a game has just been left and its last position
+ * written, so the list is not read until that has happened.
+ */
+@Composable
+private fun savedGames(env: AppEnv, stack: List<Route>): List<SavedMatch> {
+    val onMenu = stack.last() is Route.Menu
+    val saved by produceState(emptyList<SavedMatch>(), onMenu, stack.size) {
+        value = if (onMenu) withContext(Dispatchers.IO) { env.saves.all() } else emptyList()
+    }
+    return saved
+}

app/src/main/java/org/prolibertate/games/ui/EndGameHandle.kt

@@ -0,0 +1,21 @@
+package org.prolibertate.games.ui
+
+import androidx.compose.runtime.staticCompositionLocalOf
+
+/**
+ * How a screen's "End game" button tells the table to forget the saved game.
+ *
+ * Leaving a table keeps its position so it can be resumed; ending one on purpose
+ * does not. The two arrive at the screen as the same "go back", so the
+ * difference is carried here instead: [PlayScreen] provides one handle, the match
+ * it builds says what ending means for it by setting [onEnd], and each End-game
+ * dialog calls [end] before it leaves.
+ */
+class EndGameHandle {
+    /** Set by the table once it knows how to forget its own saved position. */
+    var onEnd: () -> Unit = {}
+
+    fun end() = onEnd()
+}
+
+val LocalEndGameHandle = staticCompositionLocalOf { EndGameHandle() }

app/src/main/java/org/prolibertate/games/ui/GameSetupScreen.kt

@@ -9,11 +9,14 @@ import androidx.compose.foundation.layout.fillMaxWidth
 import androidx.compose.foundation.layout.padding
 import androidx.compose.foundation.rememberScrollState
 import androidx.compose.foundation.verticalScroll
+import androidx.compose.material3.Button
+import androidx.compose.material3.Card
 import androidx.compose.material3.Divider
 import androidx.compose.material3.FilterChip
 import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.Switch
 import androidx.compose.material3.Text
+import androidx.compose.material3.TextButton
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.getValue
 import androidx.compose.runtime.mutableStateOf
@@ -29,6 +32,7 @@ import org.prolibertate.games.game.GameCatalog
 import org.prolibertate.games.game.GameDescriptor
 import org.prolibertate.games.game.engine.PlayerKind
 import org.prolibertate.games.game.engine.PlayerSlot
+import org.prolibertate.games.game.engine.SavedMatch
 import org.prolibertate.games.game.engine.TableConfig
 import org.prolibertate.games.game.backgammon.BackgammonLevel
 import org.prolibertate.games.game.backgammon.BackgammonOptions
@@ -46,6 +50,8 @@ import org.prolibertate.games.game.freecell.FreeCellOptions
 import org.prolibertate.games.game.pyramid.PyramidOptions
 import org.prolibertate.games.game.spider.SpiderOptions
 import org.prolibertate.games.game.yahtzee.YahtzeeOptions
+import org.prolibertate.games.game.meowdoku.MeowdokuGenerator
+import org.prolibertate.games.game.meowdoku.MeowdokuOptions
 import org.prolibertate.games.game.pegsolitaire.PegBoard
 import org.prolibertate.games.game.pegsolitaire.PegGoal
 import org.prolibertate.games.game.pegsolitaire.PegSolitaireOptions
@@ -58,6 +64,7 @@ import org.prolibertate.games.game.pirates.PiratesLevel
 import org.prolibertate.games.game.pirates.PiratesOptions
 import org.prolibertate.games.game.president.PresidentOptions
 import org.prolibertate.games.game.catan.CatanOptions
+import org.prolibertate.games.game.catan.CatanRuleSet
 import org.prolibertate.games.game.sequence.SequenceOptions
 import org.prolibertate.games.game.tayu.TayuLevel
 import org.prolibertate.games.game.tayu.TayuOptions
@@ -82,6 +89,10 @@ fun GameSetupScreen(
     onBack: () -> Unit,
     onPlayOffline: (TableConfig, Int) -> Unit,
     onHostOnline: (String) -> Unit,
+    /** A game of this kind left half-played, if there is one. */
+    saved: SavedMatch? = null,
+    onResume: (SavedMatch) -> Unit = {},
+    onDiscardSaved: () -> Unit = {},
 ) {
     var euchre by remember { mutableStateOf(EuchreOptions()) }
     var sequence by remember { mutableStateOf(SequenceOptions()) }
@@ -100,6 +111,7 @@ fun GameSetupScreen(
     var pirates by remember { mutableStateOf(PiratesOptions()) }
     var hearts by remember { mutableStateOf(HeartsOptions()) }
     var pegs by remember { mutableStateOf(PegSolitaireOptions()) }
+    var meowdoku by remember { mutableStateOf(MeowdokuOptions()) }
     var yahtzee by remember { mutableStateOf(YahtzeeOptions()) }
     var klondike by remember { mutableStateOf(KlondikeOptions()) }
     var freecell by remember { mutableStateOf(FreeCellOptions()) }
@@ -131,6 +143,7 @@ fun GameSetupScreen(
         GameCatalog.PIRATES -> setupJson.encodeToString(pirates)
         GameCatalog.HEARTS -> setupJson.encodeToString(hearts)
         GameCatalog.PEG_SOLITAIRE -> setupJson.encodeToString(pegs)
+        GameCatalog.MEOWDOKU -> setupJson.encodeToString(meowdoku)
         GameCatalog.YAHTZEE -> setupJson.encodeToString(yahtzee)
         GameCatalog.KLONDIKE -> setupJson.encodeToString(klondike)
         GameCatalog.FREECELL -> setupJson.encodeToString(freecell)
@@ -148,6 +161,10 @@ fun GameSetupScreen(
         ) {
             Text(descriptor.blurb, style = MaterialTheme.typography.bodyMedium)
 
+            if (saved != null) {
+                SavedGameBanner(saved, onResume = { onResume(saved) }, onDiscard = onDiscardSaved)
+            }
+
             Divider()
             Text("House rules", fontWeight = FontWeight.Bold)
 
@@ -192,6 +209,8 @@ fun GameSetupScreen(
 
                 GameCatalog.PEG_SOLITAIRE -> PegSolitaireOptionsEditor(pegs) { pegs = it }
 
+                GameCatalog.MEOWDOKU -> MeowdokuOptionsEditor(meowdoku) { meowdoku = it }
+
                 GameCatalog.YAHTZEE -> YahtzeeOptionsEditor(yahtzee) { yahtzee = it }
 
                 GameCatalog.KLONDIKE -> KlondikeOptionsEditor(klondike) { klondike = it }
@@ -232,6 +251,12 @@ fun GameSetupScreen(
                 descriptor.id == GameCatalog.PIRATES && playPirates -> 1
                 else -> 0
             }
+            if (saved != null) {
+                Text(
+                    "Starting a new game replaces the one in progress.",
+                    style = MaterialTheme.typography.bodySmall,
+                )
+            }
             PrimaryAction(text = if (solo) "Play" else "Play against the computer") {
                 onPlayOffline(
                     offlineConfig(descriptor.id, optionsJson, seatCount, playerName, localSeat),
@@ -334,9 +359,55 @@ fun teamForSeat(gameId: String, seat: Int, seatCount: Int): Int = when (gameId)
     else -> seat
 }
 
+/** The targets the setup screen offers for a Katan rule set. */
+internal fun catanPointsChoices(ruleSet: CatanRuleSet): List<Int> = when (ruleSet) {
+    // Five is a short game for trying things out; ten is the published target.
+    CatanRuleSet.BASE -> listOf(5, 8, 10, 12)
+    // Cities & Knights is played to thirteen, which is also why it runs longer.
+    CatanRuleSet.CITIES_AND_KNIGHTS -> listOf(8, 10, 13, 15)
+}
+
+/** The published target for a rule set. */
+internal fun catanDefaultPoints(ruleSet: CatanRuleSet): Int = when (ruleSet) {
+    CatanRuleSet.BASE -> 10
+    CatanRuleSet.CITIES_AND_KNIGHTS -> 13
+}
+
+/**
+ * [options] switched to [ruleSet]. The target moves to the new rule set's own
+ * default unless the one already chosen is on its menu too.
+ */
+internal fun catanSwitchRules(options: CatanOptions, ruleSet: CatanRuleSet): CatanOptions =
+    options.copy(
+        ruleSet = ruleSet,
+        pointsToWin = options.pointsToWin.takeIf { it in catanPointsChoices(ruleSet) && it != catanDefaultPoints(options.ruleSet) }
+            ?: catanDefaultPoints(ruleSet),
+    )
+
+private fun catanRuleSetName(ruleSet: CatanRuleSet): String = when (ruleSet) {
+    CatanRuleSet.BASE -> "Base game"
+    CatanRuleSet.CITIES_AND_KNIGHTS -> "Cities & Knights"
+}
+
+private fun catanRuleSetBlurb(ruleSet: CatanRuleSet): String = when (ruleSet) {
+    CatanRuleSet.BASE ->
+        "Settle the island, trade, and play development cards. Longest Road and Largest Army score."
+    CatanRuleSet.CITIES_AND_KNIGHTS ->
+        "Cities make commodities, knights hold off the barbarians, and improvements earn progress " +
+            "cards and metropolises. No development cards; the robber sleeps until the first attack."
+}
+
 @Composable
 private fun CatanOptionsEditor(options: CatanOptions, onChange: (CatanOptions) -> Unit) {
     Column(verticalArrangement = Arrangement.spacedBy(8.dp)) {
+        ChipRow(
+            label = "Rules",
+            values = CatanRuleSet.entries,
+            selected = options.ruleSet,
+            display = ::catanRuleSetName,
+            onSelect = { onChange(catanSwitchRules(options, it)) },
+        )
+        Text(catanRuleSetBlurb(options.ruleSet), style = MaterialTheme.typography.bodySmall)
         ChipRow(
             label = "Players",
             values = listOf(3, 4),
@@ -346,8 +417,7 @@ private fun CatanOptionsEditor(options: CatanOptions, onChange: (CatanOptions) -
         )
         ChipRow(
             label = "Game to",
-            // Five is a short game for trying things out; ten is the published target.
-            values = listOf(5, 8, 10, 12),
+            values = catanPointsChoices(options.ruleSet),
             selected = options.pointsToWin,
             display = { "$it points" },
             onSelect = { onChange(options.copy(pointsToWin = it)) },
@@ -1070,6 +1140,36 @@ private fun PegSolitaireOptionsEditor(
     }
 }
 
+@Composable
+private fun MeowdokuOptionsEditor(
+    options: MeowdokuOptions,
+    onChange: (MeowdokuOptions) -> Unit,
+) {
+    Column(verticalArrangement = Arrangement.spacedBy(8.dp)) {
+        ChipRow(
+            label = "Board",
+            values = (MeowdokuGenerator.MIN_SIDE..MeowdokuGenerator.MAX_SIDE).toList(),
+            selected = options.side,
+            display = { "$it × $it" },
+            onSelect = { onChange(options.copy(side = it)) },
+        )
+        ChipRow(
+            label = "Hearts",
+            values = (1..5).toList(),
+            selected = options.hearts,
+            display = { if (it == 1) "One" else "$it" },
+            onSelect = { onChange(options.copy(hearts = it)) },
+        )
+        ChipRow(
+            label = "Hints",
+            values = (0..3).toList(),
+            selected = options.hints,
+            display = { if (it == 0) "None" else "$it" },
+            onSelect = { onChange(options.copy(hints = it)) },
+        )
+    }
+}
+
 @Composable
 private fun YahtzeeOptionsEditor(options: YahtzeeOptions, onChange: (YahtzeeOptions) -> Unit) {
     Column(verticalArrangement = Arrangement.spacedBy(8.dp)) {
@@ -1170,3 +1270,30 @@ private fun PyramidOptionsEditor(options: PyramidOptions, onChange: (PyramidOpti
         onSelect = { onChange(options.copy(redeals = it)) },
     )
 }
+
+/**
+ * The game that was left unfinished, with the two things to do about it. Shown
+ * above the options so it is the first thing seen on coming back to a game.
+ */
+@Composable
+private fun SavedGameBanner(saved: SavedMatch, onResume: () -> Unit, onDiscard: () -> Unit) {
+    Card(modifier = Modifier.fillMaxWidth()) {
+        Column(
+            modifier = Modifier.padding(12.dp),
+            verticalArrangement = Arrangement.spacedBy(6.dp),
+        ) {
+            Text("Game in progress", fontWeight = FontWeight.Bold)
+            Text(
+                buildString {
+                    append("Saved ${agoText(System.currentTimeMillis(), saved.savedAtMillis)}")
+                    if (saved.summary.isNotBlank()) append(" · ${saved.summary}")
+                },
+                style = MaterialTheme.typography.bodySmall,
+            )
+            Row(horizontalArrangement = Arrangement.spacedBy(8.dp)) {
+                Button(onClick = onResume) { Text("Resume") }
+                TextButton(onClick = onDiscard) { Text("Discard") }
+            }
+        }
+    }
+}

app/src/main/java/org/prolibertate/games/ui/SavedGameText.kt

@@ -0,0 +1,24 @@
+package org.prolibertate.games.ui
+
+import org.prolibertate.games.game.engine.SavedMatch
+
+/** How long ago something happened, in the words a person would use. */
+fun agoText(nowMillis: Long, thenMillis: Long): String {
+    val seconds = ((nowMillis - thenMillis) / 1000).coerceAtLeast(0)
+    val minutes = seconds / 60
+    val hours = minutes / 60
+    val days = hours / 24
+    return when {
+        seconds < 45 -> "just now"
+        minutes < 2 -> "a minute ago"
+        minutes < 60 -> "$minutes minutes ago"
+        hours < 2 -> "an hour ago"
+        hours < 24 -> "$hours hours ago"
+        days < 2 -> "yesterday"
+        else -> "$days days ago"
+    }
+}
+
+/** "Chess · saved 5 minutes ago" for a menu line. */
+fun savedLine(title: String, match: SavedMatch, nowMillis: Long): String =
+    "$title · saved ${agoText(nowMillis, match.savedAtMillis)}"

app/src/main/java/org/prolibertate/games/ui/ScorekeeperScreen.kt

@@ -36,6 +36,7 @@ import androidx.compose.runtime.DisposableEffect
 import androidx.compose.runtime.LaunchedEffect
 import androidx.compose.runtime.collectAsState
 import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateListOf
 import androidx.compose.runtime.mutableStateMapOf
 import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.remember
@@ -114,6 +115,8 @@ fun ScorekeeperScreen(
         local = repository.sheet.first()
         loaded = true
     }
+    val recentNames by repository.recentNames.collectAsState(initial = emptyList())
+    val nameUsed: (String) -> Unit = { name -> scope.launch { repository.rememberName(name) } }
 
     val shared by session.state.collectAsState()
     val role = shared.role
@@ -220,7 +223,7 @@ fun ScorekeeperScreen(
 
             role == Role.GUEST -> Column(modifier = modifier) {
                 ConnectionBanner(shared = shared, onSync = { session.sync() })
-                Scoring(modifier = Modifier.weight(1f), sheet = sheet, onOp = change)
+                Scoring(Modifier.weight(1f), sheet, change, recentNames, nameUsed)
             }
 
             joining && role == Role.NONE ->
@@ -228,11 +231,16 @@ fun ScorekeeperScreen(
 
             !sheet.started -> SetupPane(
                 modifier = modifier,
-                onStart = { count, mode -> change(StartSheet(count, mode)) },
+                recentNames = recentNames,
+                onStart = { count, mode, names ->
+                    change(StartSheet(count, mode, names))
+                    // Last first, so the list reads in seating order.
+                    names.reversed().forEach(nameUsed)
+                },
                 onJoin = { joining = true },
             )
 
-            else -> Scoring(modifier = modifier, sheet = sheet, onOp = change)
+            else -> Scoring(modifier, sheet, change, recentNames, nameUsed)
         }
     }
 
@@ -289,9 +297,46 @@ fun ScorekeeperScreen(
 
 @OptIn(ExperimentalLayoutApi::class)
 @Composable
-private fun SetupPane(modifier: Modifier, onStart: (Int, ScoringMode) -> Unit, onJoin: () -> Unit) {
+private fun SetupPane(
+    modifier: Modifier,
+    recentNames: List<String>,
+    onStart: (Int, ScoringMode, List<String>) -> Unit,
+    onJoin: () -> Unit,
+) {
     var count by remember { mutableStateOf(ScoreSheet.DEFAULT_PLAYERS) }
     var mode by remember { mutableStateOf(ScoringMode.ROUNDS) }
+    // -1 while the options are showing; otherwise the seat being named.
+    var naming by remember { mutableStateOf(-1) }
+    val names = remember { mutableStateListOf<String>() }
+
+    if (naming >= 0) {
+        NamePane(
+            modifier = modifier,
+            seat = naming,
+            count = count,
+            name = names.getOrElse(naming) { "" },
+            // Offered once only: two players on one sheet with the same name
+            // are indistinguishable.
+            suggestions = recentNames.filter { recent ->
+                names.withIndex().none { (seat, taken) ->
+                    seat != naming && taken.trim().equals(recent.trim(), ignoreCase = true)
+                }
+            },
+            onName = { typed ->
+                while (names.size <= naming) names.add("")
+                names[naming] = typed
+            },
+            onBack = { naming -= 1 },
+            onNext = {
+                if (naming + 1 < count) {
+                    naming += 1
+                } else {
+                    onStart(count, mode, List(count) { names.getOrElse(it) { "" }.trim() })
+                }
+            },
+        )
+        return
+    }
 
     Column(
         modifier = modifier.verticalScroll(rememberScrollState()),
@@ -339,33 +384,98 @@ private fun SetupPane(modifier: Modifier, onStart: (Int, ScoringMode) -> Unit, o
             }
         }
         Text(
-            text = "Names come next: tap a column head to name it. Players can be " +
-                "added, removed or dragged into a different order at any point " +
-                "without losing anybody's score.",
+            text = "You will be asked for each name next, or skip them and tap a " +
+                "column head later. Players can be added, removed or dragged into " +
+                "a different order at any point without losing anybody's score.",
             style = MaterialTheme.typography.bodySmall,
         )
-        PrimaryAction(text = "Start scoring") { onStart(count, mode) }
+        PrimaryAction(text = "Next: name the players") { naming = 0 }
         OutlinedButton(onClick = onJoin, modifier = Modifier.fillMaxWidth()) {
             Text("Join a shared sheet nearby")
         }
     }
 }
 
+/** One seat's name, asked for on its own; a blank leaves the seat as "Player N". */
+@OptIn(ExperimentalLayoutApi::class)
+@Composable
+private fun NamePane(
+    modifier: Modifier,
+    seat: Int,
+    count: Int,
+    name: String,
+    suggestions: List<String>,
+    onName: (String) -> Unit,
+    onBack: () -> Unit,
+    onNext: () -> Unit,
+) {
+    val focus = remember { FocusRequester() }
+    LaunchedEffect(seat) { focus.requestFocus() }
+    val last = seat + 1 >= count
+    Column(
+        modifier = modifier.verticalScroll(rememberScrollState()),
+        verticalArrangement = Arrangement.spacedBy(12.dp),
+    ) {
+        Text("Player ${seat + 1} of $count", style = MaterialTheme.typography.titleMedium)
+        OutlinedTextField(
+            value = name,
+            onValueChange = onName,
+            placeholder = { Text("Player ${seat + 1}") },
+            singleLine = true,
+            keyboardOptions = KeyboardOptions(imeAction = if (last) ImeAction.Done else ImeAction.Next),
+            keyboardActions = KeyboardActions(onNext = { onNext() }, onDone = { onNext() }),
+            modifier = Modifier.fillMaxWidth().focusRequester(focus),
+        )
+        if (suggestions.isNotEmpty()) {
+            Text("Recent names", style = MaterialTheme.typography.labelMedium)
+            FlowRow(
+                horizontalArrangement = Arrangement.spacedBy(8.dp),
+                verticalArrangement = Arrangement.spacedBy(4.dp),
+            ) {
+                suggestions.forEach { recent ->
+                    FilterChip(
+                        selected = recent.equals(name.trim(), ignoreCase = true),
+                        onClick = { onName(recent) },
+                        label = { Text(recent) },
+                    )
+                }
+            }
+        }
+        PrimaryAction(text = if (last) "Start scoring" else "Next") { onNext() }
+        Row(horizontalArrangement = Arrangement.spacedBy(8.dp)) {
+            TextButton(onClick = onBack) { Text("Back") }
+            TextButton(onClick = { onName(""); onNext() }) { Text(if (last) "Skip and start" else "Skip") }
+        }
+    }
+}
+
 // ---------------------------------------------------------------------------
 // The sheet: a column per player, a row per round, totals ruled off at the foot
 // ---------------------------------------------------------------------------
 
 @Composable
-private fun Scoring(modifier: Modifier, sheet: ScoreSheet, onOp: (SheetOp) -> Unit) {
+private fun Scoring(
+    modifier: Modifier,
+    sheet: ScoreSheet,
+    onOp: (SheetOp) -> Unit,
+    recentNames: List<String>,
+    onNameUsed: (String) -> Unit,
+) {
     if (sheet.mode == ScoringMode.TALLY) {
-        TallySheet(modifier = modifier, sheet = sheet, onOp = onOp)
+        TallySheet(modifier, sheet, onOp, recentNames, onNameUsed)
     } else {
-        Sheet(modifier = modifier, sheet = sheet, onOp = onOp)
+        Sheet(modifier, sheet, onOp, recentNames, onNameUsed)
     }
 }
 
 @Composable
-private fun Sheet(modifier: Modifier, sheet: ScoreSheet, onOp: (SheetOp) -> Unit) {
+private fun Sheet(
+    modifier: Modifier,
+    sheet: ScoreSheet,
+    onOp: (SheetOp) -> Unit,
+    recentNames: List<String>,
+    onNameUsed: (String) -> Unit,
+) {
     // One scroll state shared by the head, the rows and the totals, so all three
     // move together: a column and the name over it must never come apart. Every
     // row is built the same way and is therefore exactly the same width, which
@@ -384,6 +494,9 @@ private fun Sheet(modifier: Modifier, sheet: ScoreSheet, onOp: (SheetOp) -> Unit
     var lastTyped by remember { mutableStateOf(-1) }
     // The cell to put the cursor in when a round is opened by tapping it.
     var focusPlayer by remember { mutableStateOf(-1) }
+    // Bumped when a round is finished, to put the cursor back in the first cell
+    // of the row that is now being filled in.
+    var nextRoundFocus by remember { mutableStateOf(0) }
 
     val editing = if (correcting >= 0) correction else pending
 
@@ -513,7 +626,7 @@ private fun Sheet(modifier: Modifier, sheet: ScoreSheet, onOp: (SheetOp) -> Unit
                         )
                     },
                     trailing = { EmptyCell(width = ADD_COLUMN, height = ROW_HEIGHT) },
-                ) { _, player ->
+                ) { index, player ->
                     if (correcting >= 0) {
                         // A round is being corrected above; what is typed here
                         // is kept, but only one row is edited at a time.
@@ -521,6 +634,8 @@ private fun Sheet(modifier: Modifier, sheet: ScoreSheet, onOp: (SheetOp) -> Unit
                     } else {
                         PointsField(
                             text = pending[player.id].orEmpty(),
+                            autoFocus = index == 0 && nextRoundFocus > 0,
+                            focusRequest = nextRoundFocus,
                             onText = {
                                 pending[player.id] = it
                                 lastTyped = player.id
@@ -563,6 +678,7 @@ private fun Sheet(modifier: Modifier, sheet: ScoreSheet, onOp: (SheetOp) -> Unit
                     onOp(AddRound(amountsAsPoints(pending)))
                     pending.clear()
                 }
+                nextRoundFocus += 1
                 lastTyped = -1
                 focusPlayer = -1
             },
@@ -587,6 +703,8 @@ private fun Sheet(modifier: Modifier, sheet: ScoreSheet, onOp: (SheetOp) -> Unit
         RenameDialog(
             sheet = sheet,
             player = renamed,
+            recentNames = recentNames,
+            onNameUsed = onNameUsed,
             onName = { onOp(RenamePlayer(renamed.id, it)) },
             onRemove = {
                 onOp(RemovePlayer(renamed.id))
@@ -607,7 +725,13 @@ private fun Sheet(modifier: Modifier, sheet: ScoreSheet, onOp: (SheetOp) -> Unit
  * sheet, so tapping one in the list takes it back off.
  */
 @Composable
-private fun TallySheet(modifier: Modifier, sheet: ScoreSheet, onOp: (SheetOp) -> Unit) {
+private fun TallySheet(
+    modifier: Modifier,
+    sheet: ScoreSheet,
+    onOp: (SheetOp) -> Unit,
+    recentNames: List<String>,
+    onNameUsed: (String) -> Unit,
+) {
     var renaming by remember { mutableStateOf(-1) }
 
     Column(modifier = modifier.verticalScroll(rememberScrollState()), verticalArrangement = Arrangement.spacedBy(8.dp)) {
@@ -676,6 +800,8 @@ private fun TallySheet(modifier: Modifier, sheet: ScoreSheet, onOp: (SheetOp) ->
         RenameDialog(
             sheet = sheet,
             player = renamed,
+            recentNames = recentNames,
+            onNameUsed = onNameUsed,
             onName = { onOp(RenamePlayer(renamed.id, it)) },
             onRemove = {
                 onOp(RemovePlayer(renamed.id))
@@ -961,9 +1087,14 @@ private fun PointsCell(text: String, muted: Boolean = false, onClick: (() -> Uni
 
 /** A cell being typed into. Blank means nothing entered; a typed 0 is kept and shown. */
 @Composable
-private fun PointsField(text: String, onText: (String) -> Unit, autoFocus: Boolean = false) {
+private fun PointsField(
+    text: String,
+    onText: (String) -> Unit,
+    autoFocus: Boolean = false,
+    focusRequest: Int = 0,
+) {
     val focus = remember { FocusRequester() }
-    LaunchedEffect(autoFocus) { if (autoFocus) focus.requestFocus() }
+    LaunchedEffect(autoFocus, focusRequest) { if (autoFocus) focus.requestFocus() }
     BasicTextField(
         value = text,
         onValueChange = { onText(sanitiseAmount(it)) },
@@ -1064,16 +1195,27 @@ private fun ActionBar(
     }
 }
 
+@OptIn(ExperimentalLayoutApi::class)
 @Composable
 private fun RenameDialog(
     sheet: ScoreSheet,
     player: ScorePlayer,
+    recentNames: List<String>,
+    onNameUsed: (String) -> Unit,
     onName: (String) -> Unit,
     onRemove: () -> Unit,
     onDismiss: () -> Unit,
 ) {
+    // Closing the dialog is what files the name away, so a name is remembered
+    // once rather than once per keystroke.
+    val finish = {
+        onNameUsed(player.name)
+        onDismiss()
+    }
+    val taken = sheet.players.filter { it.id != player.id }.map { it.name.trim().lowercase() }
+    val suggestions = recentNames.filter { it.trim().lowercase() !in taken }
     AlertDialog(
-        onDismissRequest = onDismiss,
+        onDismissRequest = finish,
         title = { Text("Name this column") },
         text = {
             Column(verticalArrangement = Arrangement.spacedBy(8.dp)) {
@@ -1084,6 +1226,21 @@ private fun RenameDialog(
                     singleLine = true,
                     modifier = Modifier.fillMaxWidth(),
                 )
+                if (suggestions.isNotEmpty()) {
+                    Text("Recent names", style = MaterialTheme.typography.labelMedium)
+                    FlowRow(
+                        horizontalArrangement = Arrangement.spacedBy(8.dp),
+                        verticalArrangement = Arrangement.spacedBy(4.dp),
+                    ) {
+                        suggestions.forEach { name ->
+                            FilterChip(
+                                selected = name.equals(player.name.trim(), ignoreCase = true),
+                                onClick = { onName(name) },
+                                label = { Text(name) },
+                            )
+                        }
+                    }
+                }
                 TextButton(
                     onClick = onRemove,
                     // The last two columns stay: a sheet needs somebody on it.
@@ -1091,7 +1248,7 @@ private fun RenameDialog(
                 ) { Text("Remove this player and their score") }
             }
         },
-        confirmButton = { TextButton(onClick = onDismiss) { Text("Done") } },
+        confirmButton = { TextButton(onClick = finish) { Text("Done") } },
     )
 }
 

app/src/main/java/org/prolibertate/games/ui/SettingsScreen.kt

@@ -24,6 +24,7 @@ import androidx.compose.ui.Modifier
 import androidx.compose.ui.text.font.FontWeight
 import androidx.compose.ui.unit.dp
 import kotlinx.coroutines.launch
+import kotlin.math.roundToInt
 import org.prolibertate.games.settings.Settings
 import org.prolibertate.games.update.Release
 import org.prolibertate.games.update.UpdateChannel
@@ -83,6 +84,26 @@ fun SettingsScreen(
 
             Divider()
 
+            Column {
+                Text("Text size", fontWeight = FontWeight.Bold)
+                Text(
+                    text = "${(settings.textScale * 100).roundToInt()}% — " +
+                        "scales text throughout the app, on top of your phone's setting",
+                    style = MaterialTheme.typography.bodySmall,
+                )
+                Slider(
+                    value = settings.textScale,
+                    onValueChange = { scale ->
+                        scope.launch { env.settingsRepository.setTextScale(scale) }
+                    },
+                    valueRange = Settings.MIN_TEXT_SCALE..Settings.MAX_TEXT_SCALE,
+                    // 10% increments across 80%-160%.
+                    steps = 7,
+                )
+            }
+
+            Divider()
+
             Column {
                 Text("Your name", fontWeight = FontWeight.Bold)
                 Text(

app/src/main/java/org/prolibertate/games/ui/game/BackgammonScreen.kt

@@ -1,5 +1,6 @@
 package org.prolibertate.games.ui.game
 
+import org.prolibertate.games.ui.LocalEndGameHandle
 import androidx.compose.foundation.background
 import androidx.compose.foundation.border
 import androidx.compose.foundation.clickable
@@ -378,7 +379,12 @@ private fun LeaveDialog(onEnd: () -> Unit, onKeepPlaying: () -> Unit) {
                     "at the table is told you have left."
             )
         },
-        confirmButton = { TextButton(onClick = onEnd) { Text("End the game") } },
+        confirmButton = {
+            // Ending a game on purpose also forgets the saved position: only
+            // leaving the table keeps it to be picked up again.
+            val handle = LocalEndGameHandle.current
+            TextButton(onClick = { handle.end(); onEnd() }) { Text("End the game") }
+        },
         dismissButton = { TextButton(onClick = onKeepPlaying) { Text("Keep playing") } },
     )
 }

app/src/main/java/org/prolibertate/games/ui/game/CardTable.kt

@@ -1,5 +1,6 @@
 package org.prolibertate.games.ui.game
 
+import org.prolibertate.games.ui.LocalEndGameHandle
 import androidx.compose.foundation.BorderStroke
 import androidx.compose.foundation.background
 import androidx.compose.foundation.border
@@ -79,7 +80,12 @@ fun PatienceEndDialog(what: String, onEnd: () -> Unit, onKeepPlaying: () -> Unit
         onDismissRequest = onKeepPlaying,
         title = { Text("End this game?") },
         text = { Text(what) },
-        confirmButton = { TextButton(onClick = onEnd) { Text("End the game") } },
+        confirmButton = {
+            // Ending a game on purpose also forgets the saved position: only
+            // leaving the table keeps it to be picked up again.
+            val handle = LocalEndGameHandle.current
+            TextButton(onClick = { handle.end(); onEnd() }) { Text("End the game") }
+        },
         dismissButton = { TextButton(onClick = onKeepPlaying) { Text("Keep playing") } },
     )
 }

app/src/main/java/org/prolibertate/games/ui/game/CheckersScreen.kt

@@ -1,5 +1,6 @@
 package org.prolibertate.games.ui.game
 
+import org.prolibertate.games.ui.LocalEndGameHandle
 import androidx.compose.foundation.background
 import androidx.compose.foundation.border
 import androidx.compose.foundation.clickable
@@ -314,7 +315,12 @@ private fun EndGameDialog(onEnd: () -> Unit, onKeepPlaying: () -> Unit) {
                     "at the table is told you have left."
             )
         },
-        confirmButton = { TextButton(onClick = onEnd) { Text("End the game") } },
+        confirmButton = {
+            // Ending a game on purpose also forgets the saved position: only
+            // leaving the table keeps it to be picked up again.
+            val handle = LocalEndGameHandle.current
+            TextButton(onClick = { handle.end(); onEnd() }) { Text("End the game") }
+        },
         dismissButton = { TextButton(onClick = onKeepPlaying) { Text("Keep playing") } },
     )
 }

app/src/main/java/org/prolibertate/games/ui/game/ChessScreen.kt

@@ -1,5 +1,6 @@
 package org.prolibertate.games.ui.game
 
+import org.prolibertate.games.ui.LocalEndGameHandle
 import androidx.compose.foundation.background
 import androidx.compose.foundation.border
 import androidx.compose.foundation.clickable
@@ -215,7 +216,12 @@ private fun ConfirmEndDialog(onEnd: () -> Unit, onKeepPlaying: () -> Unit) {
                     "at the table is told you have left."
             )
         },
-        confirmButton = { TextButton(onClick = onEnd) { Text("End the game") } },
+        confirmButton = {
+            // Ending a game on purpose also forgets the saved position: only
+            // leaving the table keeps it to be picked up again.
+            val handle = LocalEndGameHandle.current
+            TextButton(onClick = { handle.end(); onEnd() }) { Text("End the game") }
+        },
         dismissButton = { TextButton(onClick = onKeepPlaying) { Text("Keep playing") } },
     )
 }

app/src/main/java/org/prolibertate/games/ui/game/HeartsScreen.kt

@@ -1,5 +1,6 @@
 package org.prolibertate.games.ui.game
 
+import org.prolibertate.games.ui.LocalEndGameHandle
 import androidx.compose.foundation.layout.Arrangement
 import androidx.compose.foundation.layout.Box
 import androidx.compose.foundation.layout.Column
@@ -268,7 +269,12 @@ private fun EndHeartsDialog(onEnd: () -> Unit, onKeepPlaying: () -> Unit) {
         onDismissRequest = onKeepPlaying,
         title = { Text("End this game?") },
         text = { Text("The game ends here. Anyone else at the table is told you have left.") },
-        confirmButton = { TextButton(onClick = onEnd) { Text("End the game") } },
+        confirmButton = {
+            // Ending a game on purpose also forgets the saved position: only
+            // leaving the table keeps it to be picked up again.
+            val handle = LocalEndGameHandle.current
+            TextButton(onClick = { handle.end(); onEnd() }) { Text("End the game") }
+        },
         dismissButton = { TextButton(onClick = onKeepPlaying) { Text("Keep playing") } },
     )
 }

app/src/main/java/org/prolibertate/games/ui/game/KlondikeScreen.kt

@@ -1,5 +1,6 @@
 package org.prolibertate.games.ui.game
 
+import org.prolibertate.games.ui.LocalEndGameHandle
 import androidx.compose.foundation.BorderStroke
 import androidx.compose.foundation.background
 import androidx.compose.foundation.border
@@ -342,7 +343,12 @@ private fun EndTableDialog(onEnd: () -> Unit, onKeepPlaying: () -> Unit) {
         onDismissRequest = onKeepPlaying,
         title = { Text("End this game?") },
         text = { Text("The deal is left as it stands.") },
-        confirmButton = { TextButton(onClick = onEnd) { Text("End the game") } },
+        confirmButton = {
+            // Ending a game on purpose also forgets the saved position: only
+            // leaving the table keeps it to be picked up again.
+            val handle = LocalEndGameHandle.current
+            TextButton(onClick = { handle.end(); onEnd() }) { Text("End the game") }
+        },
         dismissButton = { TextButton(onClick = onKeepPlaying) { Text("Keep playing") } },
     )
 }

app/src/main/java/org/prolibertate/games/ui/game/MastermindScreen.kt

@@ -1,5 +1,6 @@
 package org.prolibertate.games.ui.game
 
+import org.prolibertate.games.ui.LocalEndGameHandle
 import androidx.compose.foundation.background
 import androidx.compose.foundation.border
 import androidx.compose.foundation.clickable
@@ -356,7 +357,12 @@ private fun EndDialog(onEnd: () -> Unit, onKeepPlaying: () -> Unit) {
         onDismissRequest = onKeepPlaying,
         title = { Text("End this game?") },
         text = { Text("The game ends here. Anyone else at the table is told you have left.") },
-        confirmButton = { TextButton(onClick = onEnd) { Text("End the game") } },
+        confirmButton = {
+            // Ending a game on purpose also forgets the saved position: only
+            // leaving the table keeps it to be picked up again.
+            val handle = LocalEndGameHandle.current
+            TextButton(onClick = { handle.end(); onEnd() }) { Text("End the game") }
+        },
         dismissButton = { TextButton(onClick = onKeepPlaying) { Text("Keep playing") } },
     )
 }

app/src/main/java/org/prolibertate/games/ui/game/MeowdokuScreen.kt

@@ -0,0 +1,379 @@
+package org.prolibertate.games.ui.game
+
+import androidx.compose.foundation.background
+import androidx.compose.foundation.border
+import androidx.compose.foundation.layout.Arrangement
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.BoxWithConstraints
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.Row
+import androidx.compose.foundation.layout.aspectRatio
+import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.rememberScrollState
+import androidx.compose.foundation.verticalScroll
+import androidx.compose.foundation.gestures.awaitEachGesture
+import androidx.compose.foundation.gestures.awaitFirstDown
+import androidx.compose.material3.AlertDialog
+import androidx.compose.material3.Button
+import androidx.compose.material3.FilterChip
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.Text
+import androidx.compose.material3.TextButton
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.collectAsState
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.runtime.rememberUpdatedState
+import androidx.compose.runtime.setValue
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.geometry.Offset
+import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.input.pointer.pointerInput
+import androidx.compose.ui.text.font.FontWeight
+import androidx.compose.ui.unit.dp
+import androidx.compose.ui.unit.sp
+import androidx.compose.ui.unit.TextUnit
+import org.prolibertate.games.game.meowdoku.MeowdokuMove
+import org.prolibertate.games.game.meowdoku.MeowdokuState
+import org.prolibertate.games.game.meowdoku.PlaceCat
+import org.prolibertate.games.game.meowdoku.Square
+import org.prolibertate.games.game.meowdoku.TakeHint
+import org.prolibertate.games.game.meowdoku.TogglePencil
+import org.prolibertate.games.net.MatchController
+import org.prolibertate.games.ui.LocalEndGameHandle
+import org.prolibertate.games.ui.ScreenScaffold
+import org.prolibertate.games.ui.theme.CardRed
+import kotlin.math.abs
+import kotlin.math.roundToInt
+
+private const val TITLE = "Meowdoku"
+
+/**
+ * How long the second tap of a double tap may take to arrive.
+ *
+ * 350 ms, the number the original game ships: long enough that a deliberate
+ * one-two still reads as one question, short enough that nobody pairs two
+ * taps they meant for two separate squares.
+ */
+private const val DOUBLE_TAP_WINDOW_MILLIS = 350L
+
+/**
+ * The region colours, one per cat the board can hold.
+ *
+ * The board never needs two regions of one colour — a side-ten board has ten
+ * regions and the palette has ten — so a region's colour is just its id, and
+ * nothing has to be computed to keep neighbours apart. The palette reads as
+ * watercolour on purpose: cats are dark ink on top of it, and a square the
+ * player has crossed over is too.
+ */
+private val RegionColours = listOf(
+    Color(0xFFF2C6C2), // rose
+    Color(0xFFF7E0A6), // butter
+    Color(0xFFCDE8C5), // mint
+    Color(0xFFC5E3F0), // sky
+    Color(0xFFD8CDEB), // lilac
+    Color(0xFFEBC9A0), // apricot
+    Color(0xFFBFE3D0), // spruce
+    Color(0xFFF0D7E3), // blossom
+    Color(0xFFCFCFE8), // periwinkle
+    Color(0xFFE3E7C1), // lime
+)
+
+/**
+ * The puzzle board, tapped the way the original's is.
+ *
+ * One tap crosses a square over; a second tap on the same square within
+ * [DOUBLE_TAP_WINDOW_MILLIS] asks the board whether a cat lives there. Drag
+ * strokes paint or erase crosses along the line the finger takes, which is
+ * how a row gets crossed out in one gesture rather than eight taps. Cats are
+ * permanent: tapping one does nothing, and a stroke skips over it.
+ */
+@Composable
+fun MeowdokuScreen(
+    controller: MatchController<MeowdokuState, MeowdokuMove>,
+    onNewPuzzle: () -> Unit,
+    onExit: () -> Unit,
+) {
+    val state by controller.state.collectAsState()
+    val legal by controller.legalMoves.collectAsState()
+    val abandoned by controller.abandoned.collectAsState()
+
+    var confirmingEnd by remember { mutableStateOf(false) }
+
+    val endGameAction: @Composable () -> Unit = {
+        TextButton(onClick = { confirmingEnd = true }) { Text("End game") }
+    }
+
+    val current = state
+    if (current == null) {
+        ScreenScaffold(title = TITLE, onBack = onExit, actions = endGameAction) { modifier ->
+            Box(modifier, contentAlignment = Alignment.Center) { Text("Setting up…") }
+            abandoned?.let { LeftBoardDialog(it, onExit, controller::dismissAbandoned) }
+            if (confirmingEnd) EndBoardDialog(onExit) { confirmingEnd = false }
+        }
+        return
+    }
+
+    val places = legal.filterIsInstance<PlaceCat>().map { it.square }.toSet()
+    val pencils = legal.filterIsInstance<TogglePencil>().map { it.square }.toSet()
+    val finished by controller.finished.collectAsState()
+
+    ScreenScaffold(title = TITLE, onBack = onExit, actions = endGameAction) { modifier ->
+        Column(
+            modifier = modifier.verticalScroll(rememberScrollState()),
+            verticalArrangement = Arrangement.spacedBy(10.dp),
+        ) {
+            Text(
+                text = when {
+                    current.solved -> "Found every cat" +
+                        if (current.wrongCats == 0) ", not one tap wasted." else ", with ${current.wrongCats} wrong taps."
+                    current.lost -> "Out of hearts, with ${current.side - current.catsFound} cats still hiding."
+                    else -> "${current.catsFound} of ${current.side} cats found. " +
+                        "Tap to cross a square, tap it again for a cat."
+                },
+                fontWeight = FontWeight.Bold,
+            )
+            Text(
+                text = "Hearts " + "♥".repeat(current.heartsLeft) +
+                    " · Hints " + current.hintsLeft,
+                style = MaterialTheme.typography.bodySmall,
+            )
+
+            Board(
+                state = current,
+                // Moves are refused rather than hidden: an attempt or a note
+                // the board would reject (a tap on a cat, mostly) has to die
+                // here, in the gesture, where the player can be doing nothing
+                // else the same instant.
+                onNote = { square -> if (square in pencils) controller.submit(TogglePencil(square)) },
+                onAttempt = { square -> if (square in places) controller.submit(PlaceCat(square)) },
+            )
+
+            if (TakeHint in legal) {
+                FilterChip(
+                    selected = false,
+                    onClick = { controller.submit(TakeHint) },
+                    label = { Text("Hint") },
+                )
+            }
+
+            if (finished) {
+                Row(horizontalArrangement = Arrangement.spacedBy(8.dp)) {
+                    Button(onClick = onNewPuzzle) { Text("New puzzle") }
+                    TextButton(onClick = onExit) { Text("Leave") }
+                }
+            }
+
+            current.log.takeLast(2).forEach {
+                Text(it, style = MaterialTheme.typography.bodySmall)
+            }
+        }
+
+        abandoned?.let { LeftBoardDialog(it, onExit, controller::dismissAbandoned) }
+        if (confirmingEnd) EndBoardDialog(onExit) { confirmingEnd = false }
+    }
+}
+
+/**
+ * The board as one gesture surface.
+ *
+ * Cells are drawn by weight inside a square frame, but input is not per-cell:
+ * a stroke is one continuous gesture, so the pointer works in board
+ * coordinates and maps positions to squares itself. The cell list renders
+ * underneath, and the live state is read through [rememberUpdatedState]
+ * because a gesture outlives the recompositions it lands in.
+ */
+@Composable
+private fun Board(
+    state: MeowdokuState,
+    onNote: (Square) -> Unit,
+    onAttempt: (Square) -> Unit,
+) {
+    val side = state.side
+    val current by rememberUpdatedState(state)
+    val note by rememberUpdatedState(onNote)
+    val attempt by rememberUpdatedState(onAttempt)
+
+    BoxWithConstraints(modifier = Modifier.fillMaxWidth()) {
+        // One cell's edge, so a cat is always about half a square whatever
+        // board was dealt.
+        val cell = maxWidth / side
+        Box(
+            modifier = Modifier
+                .aspectRatio(1f)
+                .pointerInput(side) {
+                    val cellPx = size.width.toFloat() / side
+                    var lastTap: Square? = null
+                    var lastTapAt = 0L
+                    awaitEachGesture {
+                        val down = awaitFirstDown(requireUnconsumed = false)
+                        val board = current
+                        val start = squareAt(down.position, cellPx, side)
+                            ?: return@awaitEachGesture
+                        if (start in board.cats) return@awaitEachGesture
+
+                        val now = System.currentTimeMillis()
+                        if (start == lastTap && now - lastTapAt < DOUBLE_TAP_WINDOW_MILLIS) {
+                            // The second tap of a pair: the cat attempt, and
+                            // no note — the cross it lands on was drawn by
+                            // this pair's first tap, and the board replaces it.
+                            lastTap = null
+                            attempt(start)
+                            do {
+                                val event = awaitPointerEvent()
+                                val change = event.changes.firstOrNull { it.id == down.id }
+                                change?.consume()
+                            } while (change != null && change.pressed)
+                            return@awaitEachGesture
+                        }
+
+                        // The first tap: a note, and the stroke that may follow
+                        // paints the same note everywhere it goes.
+                        lastTap = start
+                        lastTapAt = now
+                        val erasing = start in board.marks
+                        note(start)
+                        val marks = board.marks.toMutableSet()
+                        marks.flip(start)
+                        var previous = start
+
+                        while (true) {
+                            val event = awaitPointerEvent()
+                            val change = event.changes.firstOrNull { it.id == down.id }
+                            if (change == null || !change.pressed) break
+                            change.consume()
+                            val here = squareAt(change.position, cellPx, side) ?: continue
+                            if (here == previous) continue
+                            for (square in path(previous, here)) {
+                                if (square in board.cats) continue
+                                // `marks` is the stroke's own mirror: the base
+                                // board plus every note this stroke has
+                                // already submitted. The state flow lags a
+                                // frame behind submissions, and a stroke that
+                                // crosses a square twice must leave it at the
+                                // stroke's target, not flip it back.
+                                //
+                                // Erasing means "flip everything still
+                                // crossed"; painting means "flip everything
+                                // still blank" — which is the same test read
+                                // two ways: flip while marked == erasing.
+                                if ((square in marks) == erasing) {
+                                    note(square)
+                                    marks.flip(square)
+                                }
+                            }
+                            previous = here
+                        }
+                    }
+                }
+        ) {
+            Column(modifier = Modifier.aspectRatio(1f)) {
+                for (row in 0 until side) {
+                    Row(modifier = Modifier.weight(1f)) {
+                        for (col in 0 until side) {
+                            CellView(
+                                square = Square(row, col),
+                                state = current,
+                                glyphSize = (cell.value * 0.55f).sp,
+                                modifier = Modifier.weight(1f),
+                            )
+                        }
+                    }
+                }
+            }
+        }
+    }
+}
+
+/** Which square a pointer position is over, or null if it has left the board. */
+private fun squareAt(position: Offset, cellPx: Float, side: Int): Square? {
+    val col = (position.x / cellPx).toInt()
+    val row = (position.y / cellPx).toInt()
+    if (row !in 0 until side || col !in 0 until side) return null
+    return Square(row, col)
+}
+
+/** Add the square, or drop it if it was already there — the stroke's own toggle. */
+private fun MutableSet<Square>.flip(square: Square) {
+    if (!add(square)) remove(square)
+}
+
+/**
+ * The squares between two consecutive pointer reads, endpoints not repeated.
+ *
+ * A fast stroke publishes fewer positions than it crosses cells, so the line
+ * between two reads is walked in whole-cell steps. [path] returns at most one
+ * square per cell crossed, in order, which is what lets a stroke cross a row
+ * in one drag without missing the squares between two events.
+ */
+private fun path(from: Square, to: Square): List<Square> {
+    val dr = to.row - from.row
+    val dc = to.col - from.col
+    val steps = maxOf(abs(dr), abs(dc))
+    if (steps <= 1) return listOf(to)
+    return (1..steps).map { i ->
+        Square(
+            from.row + (dr * i.toFloat() / steps).roundToInt(),
+            from.col + (dc * i.toFloat() / steps).roundToInt(),
+        )
+    }
+}
+
+@Composable
+private fun CellView(
+    square: Square,
+    state: MeowdokuState,
+    glyphSize: TextUnit,
+    modifier: Modifier,
+) {
+    val isCat = square in state.cats
+    val isMark = square in state.marks
+    val justWrong = state.lastWrong && state.lastSquare == square
+    Box(
+        modifier = modifier
+            .aspectRatio(1f)
+            .border(1.dp, Color(0x33000000))
+            .background(RegionColours[state.regionOf(square) % RegionColours.size])
+            .then(
+                if (justWrong) Modifier.border(3.dp, CardRed) else Modifier
+            ),
+        contentAlignment = Alignment.Center,
+    ) {
+        when {
+            isCat -> Text("🐱", fontSize = glyphSize)
+            isMark -> Text(
+                "✕",
+                color = Color(0xAA1C1B1F),
+                fontWeight = FontWeight.Bold,
+                fontSize = glyphSize,
+            )
+        }
+    }
+}
+
+@Composable
+private fun EndBoardDialog(onEnd: () -> Unit, onKeepPlaying: () -> Unit) {
+    AlertDialog(
+        onDismissRequest = onKeepPlaying,
+        title = { Text("End this game?") },
+        text = { Text("The board is left as it stands.") },
+        confirmButton = {
+            val handle = LocalEndGameHandle.current
+            TextButton(onClick = { handle.end(); onEnd() }) { Text("End the game") }
+        },
+        dismissButton = { TextButton(onClick = onKeepPlaying) { Text("Keep playing") } },
+    )
+}
+
+@Composable
+private fun LeftBoardDialog(notice: String, onExit: () -> Unit, onStay: () -> Unit) {
+    AlertDialog(
+        onDismissRequest = onStay,
+        title = { Text("The game has ended") },
+        text = { Text(notice) },
+        confirmButton = { TextButton(onClick = onExit) { Text("Leave the game") } },
+        dismissButton = { TextButton(onClick = onStay) { Text("Look at the board") } },
+    )
+}

app/src/main/java/org/prolibertate/games/ui/game/MorrisScreen.kt

@@ -1,5 +1,6 @@
 package org.prolibertate.games.ui.game
 
+import org.prolibertate.games.ui.LocalEndGameHandle
 import androidx.compose.foundation.Canvas
 import androidx.compose.foundation.background
 import androidx.compose.foundation.border
@@ -483,7 +484,12 @@ private fun LeaveBoardDialog(onEnd: () -> Unit, onKeepPlaying: () -> Unit) {
                     "at the table is told you have left."
             )
         },
-        confirmButton = { TextButton(onClick = onEnd) { Text("End the game") } },
+        confirmButton = {
+            // Ending a game on purpose also forgets the saved position: only
+            // leaving the table keeps it to be picked up again.
+            val handle = LocalEndGameHandle.current
+            TextButton(onClick = { handle.end(); onEnd() }) { Text("End the game") }
+        },
         dismissButton = { TextButton(onClick = onKeepPlaying) { Text("Keep playing") } },
     )
 }

app/src/main/java/org/prolibertate/games/ui/game/PegSolitaireScreen.kt

@@ -1,5 +1,6 @@
 package org.prolibertate.games.ui.game
 
+import org.prolibertate.games.ui.LocalEndGameHandle
 import androidx.compose.foundation.BorderStroke
 import androidx.compose.foundation.background
 import androidx.compose.foundation.border
@@ -242,7 +243,12 @@ private fun EndBoardDialog(onEnd: () -> Unit, onKeepPlaying: () -> Unit) {
         onDismissRequest = onKeepPlaying,
         title = { Text("End this game?") },
         text = { Text("The board is left as it stands.") },
-        confirmButton = { TextButton(onClick = onEnd) { Text("End the game") } },
+        confirmButton = {
+            // Ending a game on purpose also forgets the saved position: only
+            // leaving the table keeps it to be picked up again.
+            val handle = LocalEndGameHandle.current
+            TextButton(onClick = { handle.end(); onEnd() }) { Text("End the game") }
+        },
         dismissButton = { TextButton(onClick = onKeepPlaying) { Text("Keep playing") } },
     )
 }

app/src/main/java/org/prolibertate/games/ui/game/PiratesScreen.kt

@@ -1,5 +1,6 @@
 package org.prolibertate.games.ui.game
 
+import org.prolibertate.games.ui.LocalEndGameHandle
 import androidx.compose.foundation.Canvas
 import androidx.compose.foundation.background
 import androidx.compose.foundation.border
@@ -371,7 +372,12 @@ private fun LeaveFieldDialog(onEnd: () -> Unit, onKeepPlaying: () -> Unit) {
                     "at the table is told you have left."
             )
         },
-        confirmButton = { TextButton(onClick = onEnd) { Text("End the game") } },
+        confirmButton = {
+            // Ending a game on purpose also forgets the saved position: only
+            // leaving the table keeps it to be picked up again.
+            val handle = LocalEndGameHandle.current
+            TextButton(onClick = { handle.end(); onEnd() }) { Text("End the game") }
+        },
         dismissButton = { TextButton(onClick = onKeepPlaying) { Text("Keep playing") } },
     )
 }

app/src/main/java/org/prolibertate/games/ui/game/TayuScreen.kt

@@ -1,5 +1,6 @@
 package org.prolibertate.games.ui.game
 
+import org.prolibertate.games.ui.LocalEndGameHandle
 import androidx.compose.foundation.Canvas
 import androidx.compose.foundation.gestures.detectTapGestures
 import androidx.compose.foundation.layout.Arrangement
@@ -668,7 +669,12 @@ private fun TayuConfirmEndDialog(onEnd: () -> Unit, onKeepPlaying: () -> Unit) {
                     "table is told you have left."
             )
         },
-        confirmButton = { TextButton(onClick = onEnd) { Text("End the game") } },
+        confirmButton = {
+            // Ending a game on purpose also forgets the saved position: only
+            // leaving the table keeps it to be picked up again.
+            val handle = LocalEndGameHandle.current
+            TextButton(onClick = { handle.end(); onEnd() }) { Text("End the game") }
+        },
         dismissButton = { TextButton(onClick = onKeepPlaying) { Text("Keep playing") } },
     )
 }

app/src/main/java/org/prolibertate/games/ui/game/YahtzeeScreen.kt

@@ -1,11 +1,16 @@
 package org.prolibertate.games.ui.game
 
+import org.prolibertate.games.ui.LocalEndGameHandle
 import androidx.compose.foundation.background
 import androidx.compose.foundation.border
 import androidx.compose.foundation.clickable
 import androidx.compose.foundation.layout.Arrangement
 import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.BoxWithConstraints
+import androidx.compose.foundation.horizontalScroll
+import androidx.compose.foundation.layout.width
 import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.Canvas
 import androidx.compose.foundation.layout.Row
 import androidx.compose.foundation.layout.fillMaxWidth
 import androidx.compose.foundation.layout.padding
@@ -29,12 +34,17 @@ import androidx.compose.runtime.remember
 import androidx.compose.runtime.setValue
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
+import androidx.compose.ui.geometry.Offset
 import androidx.compose.ui.text.font.FontWeight
 import androidx.compose.ui.unit.dp
 import org.prolibertate.games.game.yahtzee.DICE_COUNT
 import org.prolibertate.games.game.yahtzee.RollDice
 import org.prolibertate.games.game.yahtzee.ScoreIn
 import org.prolibertate.games.game.yahtzee.YahtzeeCategory
+import org.prolibertate.games.game.yahtzee.YahtzeeComparison
+import org.prolibertate.games.game.yahtzee.recordOf
+import org.prolibertate.games.settings.YahtzeeStatsRepository
+import kotlin.math.roundToInt
 import org.prolibertate.games.game.yahtzee.YahtzeeMove
 import org.prolibertate.games.game.yahtzee.YahtzeeSection
 import org.prolibertate.games.game.yahtzee.YahtzeeState
@@ -60,6 +70,7 @@ private const val TITLE = "Yahtzee"
 fun YahtzeeScreen(
     controller: MatchController<YahtzeeState, YahtzeeMove>,
     localSeat: Int,
+    stats: YahtzeeStatsRepository,
     onExit: () -> Unit,
 ) {
     val state by controller.state.collectAsState()
@@ -68,6 +79,11 @@ fun YahtzeeScreen(
 
     val kept = remember { mutableStateListOf<Int>() }
     var confirmingEnd by remember { mutableStateOf(false) }
+    var confirmingZero by remember { mutableStateOf<YahtzeeCategory?>(null) }
+    var comparison by remember { mutableStateOf<YahtzeeComparison?>(null) }
+    // Only a game seen to finish is recorded: reopening a saved game that was
+    // already over must not count it a second time.
+    var sawInProgress by remember { mutableStateOf(false) }
 
     val endGameAction: @Composable () -> Unit = {
         TextButton(onClick = { confirmingEnd = true }) { Text("End game") }
@@ -88,6 +104,15 @@ fun YahtzeeScreen(
     // refused, and the Throw button would look broken again.
     LaunchedEffect(current.turn, current.round) { kept.clear() }
 
+    LaunchedEffect(current.isOver) {
+        if (!current.isOver) {
+            sawInProgress = true
+        } else if (sawInProgress) {
+            sawInProgress = false
+            comparison = stats.finish(recordOf(current, localSeat))
+        }
+    }
+
     val yours = current.turn == localSeat && !current.isOver
     val canRoll = legal.any { it is RollDice }
     val writable = legal.filterIsInstance<ScoreIn>().map { it.category }.toSet()
@@ -137,8 +162,14 @@ fun YahtzeeScreen(
                 localSeat = localSeat,
                 writable = if (yours) writable else emptySet(),
                 onWrite = {
-                    controller.submit(ScoreIn(it))
-                    kept.clear()
+                    // A zero is a box spent for nothing, and one mis-tap on a
+                    // dense card is all it takes, so ask first.
+                    if (scoreOf(it, current.dice) == 0) {
+                        confirmingZero = it
+                    } else {
+                        controller.submit(ScoreIn(it))
+                        kept.clear()
+                    }
                 },
             )
 
@@ -149,9 +180,79 @@ fun YahtzeeScreen(
 
         abandoned?.let { LeftCardDialog(it, onExit, controller::dismissAbandoned) }
         if (confirmingEnd) EndCardDialog(onExit) { confirmingEnd = false }
+        comparison?.let { StatsDialog(it, onExit) { comparison = null } }
+        confirmingZero?.let { category ->
+            ZeroScoreDialog(
+                category = category,
+                onConfirm = {
+                    confirmingZero = null
+                    controller.submit(ScoreIn(category))
+                    kept.clear()
+                },
+                onCancel = { confirmingZero = null },
+            )
+        }
     }
 }
 
+@Composable
+private fun StatsDialog(c: YahtzeeComparison, onLeave: () -> Unit, onClose: () -> Unit) {
+    fun pct(v: Double?) = v?.let { "${(it * 100).roundToInt()}%" } ?: "—"
+    val headline = when {
+        c.previousGames == 0 -> "Your first recorded game."
+        c.rank == 1 -> "A new personal best!"
+        else -> "${ordinal(c.rank)} best of ${c.gamesRanked} games."
+    }
+    AlertDialog(
+        onDismissRequest = onClose,
+        title = { Text("Game over: ${c.current.total} points") },
+        text = {
+            Column(verticalArrangement = Arrangement.spacedBy(6.dp)) {
+                Text(headline, fontWeight = FontWeight.Bold)
+                StatLine("", "This game", "Before")
+                StatLine("Score", "${c.current.total}", c.averageBefore?.let { "avg ${it.roundToInt()}, best ${c.bestBefore}" } ?: "—")
+                StatLine("Upper bonus", if (c.current.gotBonus) "Yes" else "No", pct(c.bonusRateBefore))
+                StatLine("Yahtzees", "${c.current.yahtzees}", "${c.yahtzeesBefore} total")
+                StatLine("Zeroed boxes", "${c.current.zeros}", "")
+                if (c.current.players > 1) {
+                    StatLine("Result", if (c.current.won) "Won" else "Lost", "won ${pct(c.winRateBefore)}")
+                }
+                Text(
+                    "Games before this one: ${c.previousGames}",
+                    style = MaterialTheme.typography.bodySmall,
+                )
+            }
+        },
+        confirmButton = { TextButton(onClick = onLeave) { Text("Leave the game") } },
+        dismissButton = { TextButton(onClick = onClose) { Text("Look at the card") } },
+    )
+}
+
+@Composable
+private fun StatLine(label: String, now: String, before: String) {
+    Row(modifier = Modifier.fillMaxWidth()) {
+        Text(label, modifier = Modifier.weight(1.2f), fontWeight = FontWeight.Bold)
+        Text(now, modifier = Modifier.weight(1f))
+        Text(before, modifier = Modifier.weight(1.6f))
+    }
+}
+
+private fun ordinal(n: Int): String {
+    val suffix = if (n % 100 in 11..13) "th" else when (n % 10) { 1 -> "st"; 2 -> "nd"; 3 -> "rd"; else -> "th" }
+    return "$n$suffix"
+}
+
+@Composable
+private fun ZeroScoreDialog(category: YahtzeeCategory, onConfirm: () -> Unit, onCancel: () -> Unit) {
+    AlertDialog(
+        onDismissRequest = onCancel,
+        title = { Text("Score zero?") },
+        text = { Text("These dice are worth 0 in ${category.label}. Write the zero there?") },
+        confirmButton = { TextButton(onClick = onConfirm) { Text("Score 0") } },
+        dismissButton = { TextButton(onClick = onCancel) { Text("Choose another") } },
+    )
+}
+
 @Composable
 private fun DiceRow(
     dice: List<Int>,
@@ -189,12 +290,29 @@ private fun Die(face: Int?, held: Boolean, enabled: Boolean, onClick: () -> Unit
             .clickable(enabled = enabled) { onClick() },
         contentAlignment = Alignment.Center,
     ) {
-        Text(
-            text = face?.toString() ?: "·",
-            style = MaterialTheme.typography.titleLarge,
-            fontWeight = FontWeight.Bold,
-            color = WallaceRed,
-        )
+        if (face != null) {
+            Canvas(modifier = Modifier.size(48.dp)) {
+                val radius = size.minDimension * 0.08f
+                pipPositions(face).forEach { (x, y) ->
+                    drawCircle(WallaceRed, radius, Offset(size.width * x, size.height * y))
+                }
+            }
+        }
+    }
+}
+
+/** Pip centres as fractions of the die face, in the usual casino layout. */
+private fun pipPositions(face: Int): List<Pair<Float, Float>> {
+    val lo = 0.28f
+    val mid = 0.5f
+    val hi = 0.72f
+    return when (face) {
+        1 -> listOf(mid to mid)
+        2 -> listOf(lo to lo, hi to hi)
+        3 -> listOf(lo to lo, mid to mid, hi to hi)
+        4 -> listOf(lo to lo, hi to lo, lo to hi, hi to hi)
+        5 -> listOf(lo to lo, hi to lo, mid to mid, lo to hi, hi to hi)
+        else -> listOf(lo to lo, hi to lo, lo to mid, hi to mid, lo to hi, hi to hi)
     }
 }
 
@@ -205,28 +323,61 @@ private fun ScoreCard(
     writable: Set<YahtzeeCategory>,
     onWrite: (YahtzeeCategory) -> Unit,
 ) {
-    Column(modifier = Modifier.fillMaxWidth()) {
-        Row(modifier = Modifier.fillMaxWidth()) {
-            Text("", modifier = Modifier.weight(2f), style = MaterialTheme.typography.labelSmall)
-            state.cards.indices.forEach { seat ->
-                Text(
-                    text = if (seat == localSeat) "You" else "S$seat",
-                    modifier = Modifier.weight(1f),
-                    style = MaterialTheme.typography.labelSmall,
-                    fontWeight = FontWeight.Bold,
-                )
-            }
-        }
-        YahtzeeSection.entries.forEach { section ->
-            YahtzeeCategory.entries.filter { it.section == section }.forEach { category ->
-                CardRow(state, localSeat, category, writable, onWrite)
-            }
-            if (section == YahtzeeSection.UPPER) {
+    // Upper boxes and bonus on the left, lower boxes and total on the right, so
+    // each half is wide enough for text that can actually be read. Each half
+    // has a floor on its width; if two of them do not fit (many players, large
+    // text) the pair scrolls sideways instead of squeezing.
+    BoxWithConstraints(modifier = Modifier.fillMaxWidth()) {
+        val needed = (CARD_LABEL_WIDTH + CARD_SEAT_WIDTH * state.cards.size).dp
+        val half = maxOf((maxWidth - CARD_GAP.dp) / 2, needed)
+        Row(
+            modifier = Modifier.horizontalScroll(rememberScrollState()),
+            horizontalArrangement = Arrangement.spacedBy(CARD_GAP.dp),
+        ) {
+            Column(modifier = Modifier.width(half)) {
+                CardHeader(state, localSeat)
+                CardSection(YahtzeeSection.UPPER, state, localSeat, writable, onWrite)
                 TotalRow("Bonus at 63", state.cards.map { it.upperBonus })
             }
+            Column(modifier = Modifier.width(half)) {
+                CardHeader(state, localSeat)
+                CardSection(YahtzeeSection.LOWER, state, localSeat, writable, onWrite)
+                Divider()
+                TotalRow("Total", state.cards.indices.map { state.totalFor(it) }, bold = true)
+            }
         }
-        Divider()
-        TotalRow("Total", state.cards.indices.map { state.totalFor(it) }, bold = true)
+    }
+}
+
+private const val CARD_LABEL_WIDTH = 120
+private const val CARD_SEAT_WIDTH = 56
+private const val CARD_GAP = 12
+
+@Composable
+private fun CardHeader(state: YahtzeeState, localSeat: Int) {
+    Row(modifier = Modifier.fillMaxWidth()) {
+        Text("", modifier = Modifier.weight(2f))
+        state.cards.indices.forEach { seat ->
+            Text(
+                text = if (seat == localSeat) "You" else "S$seat",
+                modifier = Modifier.weight(1f),
+                style = MaterialTheme.typography.labelLarge,
+                fontWeight = FontWeight.Bold,
+            )
+        }
+    }
+}
+
+@Composable
+private fun CardSection(
+    section: YahtzeeSection,
+    state: YahtzeeState,
+    localSeat: Int,
+    writable: Set<YahtzeeCategory>,
+    onWrite: (YahtzeeCategory) -> Unit,
+) {
+    YahtzeeCategory.entries.filter { it.section == section }.forEach { category ->
+        CardRow(state, localSeat, category, writable, onWrite)
     }
 }
 
@@ -243,12 +394,12 @@ private fun CardRow(
         modifier = Modifier
             .fillMaxWidth()
             .clickable(enabled = open) { onWrite(category) }
-            .padding(vertical = 2.dp),
+            .padding(vertical = 5.dp),
     ) {
         Text(
             text = category.label,
             modifier = Modifier.weight(2f),
-            style = MaterialTheme.typography.bodySmall,
+            style = MaterialTheme.typography.bodyMedium,
             fontWeight = if (open) FontWeight.Bold else FontWeight.Normal,
         )
         state.cards.forEachIndexed { seat, card ->
@@ -262,7 +413,7 @@ private fun CardRow(
                     else -> "—"
                 },
                 modifier = Modifier.weight(1f),
-                style = MaterialTheme.typography.bodySmall,
+                style = MaterialTheme.typography.bodyMedium,
                 color = if (written == null && open) WallaceRed else MaterialTheme.colorScheme.onSurface,
             )
         }
@@ -271,18 +422,18 @@ private fun CardRow(
 
 @Composable
 private fun TotalRow(label: String, values: List<Int>, bold: Boolean = false) {
-    Row(modifier = Modifier.fillMaxWidth().padding(vertical = 2.dp)) {
+    Row(modifier = Modifier.fillMaxWidth().padding(vertical = 5.dp)) {
         Text(
             text = label,
             modifier = Modifier.weight(2f),
-            style = MaterialTheme.typography.bodySmall,
+            style = MaterialTheme.typography.bodyMedium,
             fontWeight = if (bold) FontWeight.Bold else FontWeight.Normal,
         )
         values.forEach {
             Text(
                 text = "$it",
                 modifier = Modifier.weight(1f),
-                style = MaterialTheme.typography.bodySmall,
+                style = MaterialTheme.typography.bodyMedium,
                 fontWeight = if (bold) FontWeight.Bold else FontWeight.Normal,
             )
         }
@@ -295,7 +446,12 @@ private fun EndCardDialog(onEnd: () -> Unit, onKeepPlaying: () -> Unit) {
         onDismissRequest = onKeepPlaying,
         title = { Text("End this game?") },
         text = { Text("The game ends here. Anyone else at the table is told you have left.") },
-        confirmButton = { TextButton(onClick = onEnd) { Text("End the game") } },
+        confirmButton = {
+            // Ending a game on purpose also forgets the saved position: only
+            // leaving the table keeps it to be picked up again.
+            val handle = LocalEndGameHandle.current
+            TextButton(onClick = { handle.end(); onEnd() }) { Text("End the game") }
+        },
         dismissButton = { TextButton(onClick = onKeepPlaying) { Text("Keep playing") } },
     )
 }

app/src/main/java/org/prolibertate/games/ui/game/catan/CatanBoardView.kt

@@ -14,6 +14,7 @@ import androidx.compose.ui.geometry.Offset
 import androidx.compose.ui.geometry.Size
 import androidx.compose.ui.graphics.Color
 import androidx.compose.ui.graphics.Path
+import androidx.compose.ui.graphics.PathEffect
 import androidx.compose.ui.graphics.StrokeCap
 import androidx.compose.ui.graphics.drawscope.DrawScope
 import androidx.compose.ui.graphics.drawscope.Stroke
@@ -58,6 +59,13 @@ fun CatanBoardView(
     style: CatanStyle = LocalCatanStyle.current,
     /** Hexes to light up as having produced on the latest roll. */
     rolledHexes: Set<Int> = emptySet(),
+    /** Cities & Knights: the knight whose menu is open or that is about to move. */
+    selectedKnight: Int? = null,
+    /** A placement lined up but not yet confirmed (or being dragged over): drawn as a solid ghost. */
+    stagedVertex: Int? = null,
+    stagedEdge: Int? = null,
+    /** The seat that will own the staged piece, for its colour. */
+    stagedSeat: Int? = null,
 ) {
     val measurer = rememberTextMeasurer()
     var size by remember { mutableStateOf(IntSize.Zero) }
@@ -86,8 +94,8 @@ fun CatanBoardView(
                     val at = Pt(tap.x, tap.y)
                     val reach = board.radius * style.tapReach
                     when {
-                        targets.vertices.isNotEmpty() ->
-                            board.nearestVertex(at, reach, targets.vertices)?.let { vertexTap(it) }
+                        targets.tappableVertices.isNotEmpty() ->
+                            board.nearestVertex(at, reach, targets.tappableVertices)?.let { vertexTap(it) }
 
                         targets.edges.isNotEmpty() ->
                             board.nearestEdge(at, reach, targets.edges)?.let { edgeTap(it) }
@@ -105,11 +113,17 @@ fun CatanBoardView(
         drawHexes(state, board, style, measurer)
         drawRolled(rolledHexes, board, style)
         drawRobber(state, board, style)
+        drawMerchant(state, board, style, measurer)
         drawRoads(state, board, style)
         drawEdgeTargets(targets, board, style)
         drawBuildings(state, board, style)
-        drawVertexTargets(targets, selectedVertex, board, style)
+        drawWalls(state, board, style)
+        drawMetropolises(state, board, style)
+        drawKnights(state, board, style)
+        drawKnightTargets(targets, board, style)
+        drawVertexTargets(targets, selectedVertex ?: selectedKnight, board, style)
         drawHexTargets(targets, board, style)
+        drawStaged(stagedVertex, stagedEdge, stagedSeat, board, style)
     }
 }
 
@@ -185,6 +199,10 @@ private fun DrawScope.drawToken(
 }
 
 private fun DrawScope.drawRobber(state: CatanState, board: BoardLayout, style: CatanStyle) {
+    // In Cities & Knights the robber sleeps, drawn faintly, until the barbarians first land.
+    val asleep = state.ck?.attacked == false
+    val tint = if (asleep) style.robber.copy(alpha = 0.3f) else style.robber
+    val rim = Color.White.copy(alpha = if (asleep) 0.25f else 0.7f)
     val hex = board.hexCenter(state.robber)
     // Beside the number token rather than on it, so the number stays readable.
     val x = hex.x + board.radius * 0.5f
@@ -197,11 +215,11 @@ private fun DrawScope.drawRobber(state: CatanState, board: BoardLayout, style: C
         lineTo(x + s * 0.55f, y + s * 0.9f)
         close()
     }
-    drawPath(pawn, color = style.robber)
-    drawCircle(color = style.robber, radius = s * 0.38f, center = Offset(x, y - s * 0.42f))
-    drawPath(pawn, color = Color.White.copy(alpha = 0.7f), style = Stroke(width = s * 0.07f))
+    drawPath(pawn, color = tint)
+    drawCircle(color = tint, radius = s * 0.38f, center = Offset(x, y - s * 0.42f))
+    drawPath(pawn, color = rim, style = Stroke(width = s * 0.07f))
     drawCircle(
-        color = Color.White.copy(alpha = 0.7f),
+        color = rim,
         radius = s * 0.38f,
         center = Offset(x, y - s * 0.42f),
         style = Stroke(width = s * 0.07f),
@@ -409,6 +427,131 @@ private fun cityPath(at: Pt, s: Float): Path = Path().apply {
     close()
 }
 
+// ---------------------------------------------------------------------------
+// Cities & Knights pieces
+// ---------------------------------------------------------------------------
+
+/** A dashed wall round each walled city, crenellated by the dashes. */
+private fun DrawScope.drawWalls(state: CatanState, board: BoardLayout, style: CatanStyle) {
+    val walls = state.ck?.walls ?: return
+    for (vertex in walls) {
+        val at = board.vertex(vertex).offset()
+        val radius = board.radius * style.citySize * 1.25f
+        val dash = PathEffect.dashPathEffect(floatArrayOf(radius * 0.38f, radius * 0.22f))
+        drawCircle(
+            color = style.pieceOutline,
+            radius = radius,
+            center = at,
+            style = Stroke(width = board.radius * 0.13f, pathEffect = dash),
+        )
+        drawCircle(
+            color = style.wall,
+            radius = radius,
+            center = at,
+            style = Stroke(width = board.radius * 0.09f, pathEffect = dash),
+        )
+    }
+}
+
+/** A pennant in the track's colour flying over a city that carries its metropolis. */
+private fun DrawScope.drawMetropolises(state: CatanState, board: BoardLayout, style: CatanStyle) {
+    val metropolises = state.ck?.metropolises ?: return
+    for ((track, at) in metropolises) {
+        val base = board.vertex(at.vertex)
+        val unit = board.radius * style.citySize
+        val poleTop = Pt(base.x + unit * 0.9f, base.y - unit * 2.0f)
+        val poleBottom = Pt(base.x + unit * 0.9f, base.y - unit * 0.4f)
+        drawLine(
+            color = style.pieceOutline,
+            start = poleBottom.offset(),
+            end = poleTop.offset(),
+            strokeWidth = board.radius * 0.05f,
+        )
+        val flag = Path().apply {
+            moveTo(poleTop.x, poleTop.y)
+            lineTo(poleTop.x + unit * 1.1f, poleTop.y + unit * 0.35f)
+            lineTo(poleTop.x, poleTop.y + unit * 0.7f)
+            close()
+        }
+        drawPath(flag, color = style.track.getValue(track))
+        drawPath(flag, color = style.pieceOutline, style = Stroke(width = board.radius * 0.035f))
+    }
+}
+
+/**
+ * Each knight is a shield in its owner's colour, marked with one, two or three
+ * dots for its strength. A sleeping knight is drawn faded; an awake one has a
+ * bright rim.
+ */
+private fun DrawScope.drawKnights(state: CatanState, board: BoardLayout, style: CatanStyle) {
+    val knights = state.ck?.knights ?: return
+    for (knight in knights) {
+        val at = board.vertex(knight.vertex)
+        val s = board.radius * style.knightSize
+        val seat = style.seats[knight.owner % style.seats.size]
+        val path = shieldPath(at, s)
+        if (knight.active) {
+            drawPath(path, color = style.knightReady, style = Stroke(width = s * 0.55f))
+        }
+        drawPath(path, color = if (knight.active) seat else seat.copy(alpha = 0.55f))
+        drawPath(path, color = style.pieceOutline, style = Stroke(width = s * 0.16f))
+        val pip = s * 0.14f
+        val gap = pip * 2.8f
+        val startX = at.x - gap * (knight.level - 1) / 2f
+        for (i in 0 until knight.level) {
+            drawCircle(
+                color = style.pieceOutline,
+                radius = pip,
+                center = Offset(startX + i * gap, at.y - s * 0.05f),
+            )
+        }
+    }
+}
+
+private fun shieldPath(at: Pt, s: Float): Path = Path().apply {
+    moveTo(at.x - s * 0.8f, at.y - s)
+    lineTo(at.x + s * 0.8f, at.y - s)
+    lineTo(at.x + s * 0.8f, at.y + s * 0.1f)
+    quadraticBezierTo(at.x + s * 0.8f, at.y + s * 0.9f, at.x, at.y + s * 1.25f)
+    quadraticBezierTo(at.x - s * 0.8f, at.y + s * 0.9f, at.x - s * 0.8f, at.y + s * 0.1f)
+    close()
+}
+
+/** A ring round each of the player's knights that can do something now. */
+private fun DrawScope.drawKnightTargets(targets: BoardTargets, board: BoardLayout, style: CatanStyle) {
+    for (vertex in targets.knights) {
+        drawCircle(
+            color = style.target,
+            radius = board.radius * style.knightSize * 1.9f,
+            center = board.vertex(vertex).offset(),
+            style = Stroke(width = board.radius * 0.07f),
+        )
+    }
+}
+
+/** The merchant: a coin in its controller's colour, beside the hex it sits on. */
+private fun DrawScope.drawMerchant(
+    state: CatanState,
+    board: BoardLayout,
+    style: CatanStyle,
+    measurer: TextMeasurer,
+) {
+    val merchant = state.ck?.merchant ?: return
+    val hex = board.hexCenter(merchant.hex)
+    val at = Pt(hex.x - board.radius * 0.5f, hex.y + board.radius * 0.3f)
+    val r = board.radius * 0.2f
+    drawCircle(color = style.seats[merchant.seat % style.seats.size], radius = r, center = at.offset())
+    drawCircle(color = style.pieceOutline, radius = r, center = at.offset(), style = Stroke(width = r * 0.3f))
+    drawCentered(
+        measurer = measurer,
+        text = "M",
+        at = at,
+        fontPx = r * 1.3f,
+        color = style.pieceOutline,
+        weight = FontWeight.ExtraBold,
+    )
+}
+
 // ---------------------------------------------------------------------------
 // Tap targets
 // ---------------------------------------------------------------------------
@@ -505,3 +648,21 @@ private fun DrawScope.drawCentered(
         topLeft = Offset(at.x - layout.size.width / 2f, at.y - layout.size.height / 2f),
     )
 }
+
+/** The ghost of a placement waiting for ✓: a solid piece in the player's colour with a bright ring. */
+private fun DrawScope.drawStaged(vertex: Int?, edge: Int?, seat: Int?, board: BoardLayout, style: CatanStyle) {
+    val colour = seat?.let { style.seats.getOrNull(it) } ?: style.target
+    if (edge != null) {
+        val (a, b) = board.edgeEnds(edge)
+        val from = lerp(a, b, 0.1f)
+        val to = lerp(a, b, 0.9f)
+        drawLine(style.targetSelected, from.offset(), to.offset(), board.radius * style.roadWidth * 2.1f, StrokeCap.Round)
+        drawLine(colour, from.offset(), to.offset(), board.radius * style.roadWidth * 1.3f, StrokeCap.Round)
+    }
+    if (vertex != null) {
+        val at = board.vertex(vertex).offset()
+        val radius = board.radius * style.targetRadius
+        drawCircle(colour, radius * 1.3f, at)
+        drawCircle(style.targetSelected, radius * 1.9f, at, style = Stroke(width = board.radius * 0.1f))
+    }
+}

app/src/main/java/org/prolibertate/games/ui/game/catan/CatanCkDialogs.kt

@@ -0,0 +1,813 @@
+package org.prolibertate.games.ui.game.catan
+
+import androidx.compose.foundation.background
+import androidx.compose.foundation.layout.Arrangement
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.ExperimentalLayoutApi
+import androidx.compose.foundation.layout.FlowRow
+import androidx.compose.foundation.layout.PaddingValues
+import androidx.compose.foundation.layout.Row
+import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.height
+import androidx.compose.foundation.layout.heightIn
+import androidx.compose.foundation.layout.size
+import androidx.compose.foundation.layout.width
+import androidx.compose.foundation.rememberScrollState
+import androidx.compose.foundation.shape.RoundedCornerShape
+import androidx.compose.foundation.verticalScroll
+import androidx.compose.material3.AlertDialog
+import androidx.compose.material3.Button
+import androidx.compose.material3.FilledTonalButton
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.OutlinedButton
+import androidx.compose.material3.Text
+import androidx.compose.material3.TextButton
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.runtime.setValue
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.draw.clip
+import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.text.font.FontWeight
+import androidx.compose.ui.unit.dp
+import org.prolibertate.games.game.catan.AcceptCounter
+import org.prolibertate.games.game.catan.ActivateKnight
+import org.prolibertate.games.game.catan.BuyImprovement
+import org.prolibertate.games.game.catan.CatanCk
+import org.prolibertate.games.game.catan.CatanMove
+import org.prolibertate.games.game.catan.CatanState
+import org.prolibertate.games.game.catan.ChaseRobber
+import org.prolibertate.games.game.catan.CounterGoods
+import org.prolibertate.games.game.catan.DropProgress
+import org.prolibertate.games.game.catan.GoodsBankTrade
+import org.prolibertate.games.game.catan.Good
+import org.prolibertate.games.game.catan.GoodsCounter
+import org.prolibertate.games.game.catan.GoodsOffer
+import org.prolibertate.games.game.catan.IMPROVEMENT_MAX
+import org.prolibertate.games.game.catan.MoveKnight
+import org.prolibertate.games.game.catan.OfferGoods
+import org.prolibertate.games.game.catan.PickDeck
+import org.prolibertate.games.game.catan.PlayProgress
+import org.prolibertate.games.game.catan.ProgressCard
+import org.prolibertate.games.game.catan.ProgressType
+import org.prolibertate.games.game.catan.PromoteKnight
+import org.prolibertate.games.game.catan.SpyTake
+import org.prolibertate.games.game.catan.TakeAqueduct
+import org.prolibertate.games.game.catan.Track
+
+/*
+ * The Cities & Knights dialogs. Like the base game's, each is a stateless
+ * composable apart from the choice it is helping the player make, and what is
+ * allowed is always asked of the engine's legal list through CatanInteraction.
+ */
+
+// ---------------------------------------------------------------------------
+// Shared pieces
+// ---------------------------------------------------------------------------
+
+/** A card tile with a minus and a plus, for choosing how many of a good. */
+@Composable
+private fun GoodCounter(good: Good, count: Int, max: Int, onChange: (Int) -> Unit) {
+    Column(horizontalAlignment = Alignment.CenterHorizontally, verticalArrangement = Arrangement.spacedBy(4.dp)) {
+        GoodTile(good, count, enabled = max > 0 || count > 0)
+        Row(horizontalArrangement = Arrangement.spacedBy(4.dp)) {
+            OutlinedButton(
+                onClick = { onChange(count - 1) },
+                enabled = count > 0,
+                contentPadding = PaddingValues(0.dp),
+                modifier = Modifier.width(34.dp).height(32.dp),
+            ) { Text("−") }
+            OutlinedButton(
+                onClick = { onChange(count + 1) },
+                enabled = count < max,
+                contentPadding = PaddingValues(0.dp),
+                modifier = Modifier.width(34.dp).height(32.dp),
+            ) { Text("+") }
+        }
+    }
+}
+
+private fun Map<Good, Int>.asGoods(): List<Good> = Good.entries.flatMap { g -> List(this[g] ?: 0) { g } }
+
+/** A row of the three track colours, used for decks and improvements. */
+@Composable
+private fun TrackChip(track: Track, style: CatanStyle = LocalCatanStyle.current) {
+    Box(
+        modifier = Modifier
+            .size(14.dp)
+            .clip(RoundedCornerShape(3.dp))
+            .background(style.track.getValue(track)),
+    )
+}
+
+// ---------------------------------------------------------------------------
+// Choosing cards to give up
+// ---------------------------------------------------------------------------
+
+/**
+ * Pick exactly [quota] cards out of [held] — to discard on a seven or a saboteur,
+ * or to hand over for a wedding or a commercial harbour. Not dismissable: the
+ * game is waiting on it. [allowed] is the engine's structural check, so the
+ * confirm button only lights when the move would be accepted.
+ */
+@OptIn(ExperimentalLayoutApi::class)
+@Composable
+fun CatanGoodsPickDialog(
+    title: String,
+    intro: String,
+    held: Map<Good, Int>,
+    quota: Int,
+    confirmLabel: String,
+    selectable: (Good) -> Boolean,
+    allowed: (List<Good>) -> Boolean,
+    onConfirm: (List<Good>) -> Unit,
+) {
+    var picked by remember { mutableStateOf(emptyMap<Good, Int>()) }
+    val selection = picked.asGoods()
+    AlertDialog(
+        onDismissRequest = {},
+        title = { Text(title) },
+        text = {
+            Column(verticalArrangement = Arrangement.spacedBy(12.dp)) {
+                Text("$intro (${selection.size} of $quota chosen).")
+                FlowRow(
+                    horizontalArrangement = Arrangement.spacedBy(8.dp),
+                    verticalArrangement = Arrangement.spacedBy(8.dp),
+                ) {
+                    Good.entries.forEach { good ->
+                        val have = held[good] ?: 0
+                        if (have > 0 && selectable(good)) {
+                            GoodCounter(
+                                good = good,
+                                count = picked[good] ?: 0,
+                                max = if (selection.size < quota) have else (picked[good] ?: 0),
+                                onChange = { n -> picked = picked + (good to n.coerceIn(0, have)) },
+                            )
+                        }
+                    }
+                }
+            }
+        },
+        confirmButton = {
+            Button(onClick = { onConfirm(selection) }, enabled = allowed(selection)) { Text(confirmLabel) }
+        },
+    )
+}
+
+// ---------------------------------------------------------------------------
+// City improvements
+// ---------------------------------------------------------------------------
+
+/** The three improvement tracks: where the player stands, what the next level costs, and what it earns. */
+@Composable
+fun CatanImproveDialog(
+    state: CatanState,
+    seat: Int,
+    legal: List<CatanMove>,
+    onBuy: (BuyImprovement) -> Unit,
+    onCancel: () -> Unit,
+) {
+    val ck = state.ck ?: return
+    val buyable = CatanInteraction.improvable(legal)
+    AlertDialog(
+        onDismissRequest = onCancel,
+        title = { Text(CatanText.IMPROVE) },
+        text = {
+            Column(
+                modifier = Modifier.heightIn(max = 460.dp).verticalScroll(rememberScrollState()),
+                verticalArrangement = Arrangement.spacedBy(14.dp),
+            ) {
+                Track.entries.forEach { track ->
+                    val level = CatanCk.improvement(state, seat, track)
+                    val have = ck.commodities[seat][track.commodity] ?: 0
+                    Column(verticalArrangement = Arrangement.spacedBy(4.dp)) {
+                        Row(verticalAlignment = Alignment.CenterVertically, horizontalArrangement = Arrangement.spacedBy(6.dp)) {
+                            TrackChip(track)
+                            Text(CatanText.track(track), fontWeight = FontWeight.Bold)
+                            Text("level $level of $IMPROVEMENT_MAX", style = MaterialTheme.typography.labelMedium)
+                        }
+                        Text(CatanText.trackPower(track), style = MaterialTheme.typography.bodySmall)
+                        if (level >= IMPROVEMENT_MAX) {
+                            Text("Fully built.", style = MaterialTheme.typography.bodySmall)
+                        } else {
+                            val cost = CatanCk.improvementCost(state, seat, track)
+                            Button(onClick = { onBuy(BuyImprovement(track)) }, enabled = track in buyable) {
+                                Text(
+                                    "${CatanCk.improvementName(track, level + 1)}: $cost " +
+                                        "${CatanText.good(Good.of(track.commodity))} (you hold $have)",
+                                )
+                            }
+                            if (level + 1 == org.prolibertate.games.game.catan.METROPOLIS_LEVEL ||
+                                level + 1 == IMPROVEMENT_MAX
+                            ) {
+                                Text(
+                                    if (level + 1 == IMPROVEMENT_MAX) {
+                                        "Level five takes a metropolis from a seat still on four."
+                                    } else {
+                                        "Level four earns the first metropolis in this track: two more points."
+                                    },
+                                    style = MaterialTheme.typography.labelSmall,
+                                )
+                            }
+                        }
+                    }
+                }
+            }
+        },
+        confirmButton = {},
+        dismissButton = { TextButton(onClick = onCancel) { Text("Close") } },
+    )
+}
+
+// ---------------------------------------------------------------------------
+// Progress cards
+// ---------------------------------------------------------------------------
+
+/**
+ * The player's progress cards. A card with nothing to decide plays at once; one
+ * that names a seat, a card or dice asks for it in a second step; one that
+ * needs a tap on the board closes the dialog and arms the board (see [ArmedCard]).
+ */
+@OptIn(ExperimentalLayoutApi::class)
+@Composable
+fun CatanProgressDialog(
+    hand: List<ProgressInHand>,
+    seats: CatanSeats,
+    onPlay: (CatanMove) -> Unit,
+    onArm: (ArmedCard) -> Unit,
+    onCancel: () -> Unit,
+) {
+    var chosen by remember { mutableStateOf<ProgressInHand?>(null) }
+    var target by remember { mutableStateOf<Int?>(null) }
+    var yellow by remember { mutableStateOf(1) }
+    var red by remember { mutableStateOf(1) }
+    val entry = chosen
+
+    AlertDialog(
+        onDismissRequest = onCancel,
+        title = { Text(entry?.let { CatanText.progress(it.card.kind) } ?: "Progress cards") },
+        text = {
+            Column(
+                modifier = Modifier.heightIn(max = 440.dp).verticalScroll(rememberScrollState()),
+                verticalArrangement = Arrangement.spacedBy(10.dp),
+            ) {
+                if (entry == null) {
+                    if (hand.isEmpty()) Text("You hold no progress cards.")
+                    hand.forEach { card ->
+                        ProgressRow(card) { picked ->
+                            val kind = picked.card.kind
+                            when {
+                                kind in CatanInteraction.BOARD_CARDS -> onArm(ArmedCard(kind, picked.plays))
+                                picked.plays.size == 1 && picked.plays[0].isBare() -> onPlay(picked.plays[0])
+                                else -> {
+                                    chosen = picked
+                                    target = null
+                                }
+                            }
+                        }
+                    }
+                } else {
+                    Text(CatanText.progressHelp(entry.card.kind), style = MaterialTheme.typography.bodySmall)
+                    val kind = entry.card.kind
+                    val plays = entry.plays
+                    when {
+                        kind == ProgressType.ALCHEMIST -> {
+                            Text("Production die (yellow)", fontWeight = FontWeight.Bold)
+                            DiePicker(yellow) { yellow = it }
+                            Text("Progress die (red)", fontWeight = FontWeight.Bold)
+                            DiePicker(red) { red = it }
+                        }
+
+                        kind == ProgressType.DESERTER || kind == ProgressType.SPY -> {
+                            Text("Choose a player:", fontWeight = FontWeight.Bold)
+                            plays.mapNotNull { it.target }.distinct().forEach { seat ->
+                                OutlinedButton(
+                                    onClick = { plays.firstOrNull { it.target == seat }?.let(onPlay) },
+                                    modifier = Modifier.fillMaxWidth(),
+                                ) { Text(seats.label(seat)) }
+                            }
+                        }
+
+                        kind == ProgressType.MASTER_MERCHANT -> {
+                            Text("Choose a player with more points:", fontWeight = FontWeight.Bold)
+                            Row(horizontalArrangement = Arrangement.spacedBy(8.dp)) {
+                                plays.mapNotNull { it.target }.distinct().forEach { seat ->
+                                    if (target == seat) {
+                                        FilledTonalButton(onClick = { target = seat }) { Text(seats.label(seat)) }
+                                    } else {
+                                        OutlinedButton(onClick = { target = seat }) { Text(seats.label(seat)) }
+                                    }
+                                }
+                            }
+                            val seat = target
+                            if (seat != null) {
+                                Text("Take:", fontWeight = FontWeight.Bold)
+                                plays.filter { it.target == seat }.forEach { play ->
+                                    OutlinedButton(
+                                        onClick = { onPlay(play) },
+                                        modifier = Modifier.fillMaxWidth(),
+                                    ) { Text(CatanText.goods(play.goods.orEmpty())) }
+                                }
+                            }
+                        }
+
+                        else -> {
+                            val label = when (kind) {
+                                ProgressType.COMMERCIAL_HARBOR -> "Offer which resource?"
+                                ProgressType.MERCHANT_FLEET -> "Trade which card two for one?"
+                                ProgressType.RESOURCE_MONOPOLY -> "Name a resource:"
+                                else -> "Name a commodity:"
+                            }
+                            Text(label, fontWeight = FontWeight.Bold)
+                            FlowRow(
+                                horizontalArrangement = Arrangement.spacedBy(8.dp),
+                                verticalArrangement = Arrangement.spacedBy(8.dp),
+                            ) {
+                                plays.mapNotNull { it.good }.distinct().forEach { good ->
+                                    GoodTile(
+                                        good = good,
+                                        count = 0,
+                                        onClick = { plays.firstOrNull { it.good == good }?.let(onPlay) },
+                                    )
+                                }
+                            }
+                        }
+                    }
+                }
+            }
+        },
+        confirmButton = {
+            if (entry != null && entry.card.kind == ProgressType.ALCHEMIST) {
+                val play = entry.plays.firstOrNull { it.dice == listOf(yellow, red) }
+                Button(onClick = { play?.let(onPlay) }, enabled = play != null) { Text("Play") }
+            }
+        },
+        dismissButton = {
+            TextButton(
+                onClick = {
+                    if (entry == null) {
+                        onCancel()
+                    } else {
+                        chosen = null
+                        target = null
+                    }
+                },
+            ) { Text(if (entry == null) CatanText.CANCEL else "Back") }
+        },
+    )
+}
+
+private fun PlayProgress.isBare(): Boolean =
+    target == null && vertex == null && edge == null && hexA == null && hexB == null &&
+        good == null && dice == null && goods == null
+
+@Composable
+private fun DiePicker(selected: Int, onPick: (Int) -> Unit) {
+    Row(horizontalArrangement = Arrangement.spacedBy(6.dp)) {
+        (1..6).forEach { n ->
+            if (n == selected) {
+                FilledTonalButton(
+                    onClick = { onPick(n) },
+                    contentPadding = PaddingValues(0.dp),
+                    modifier = Modifier.size(40.dp),
+                ) { Text("$n") }
+            } else {
+                OutlinedButton(
+                    onClick = { onPick(n) },
+                    contentPadding = PaddingValues(0.dp),
+                    modifier = Modifier.size(40.dp),
+                ) { Text("$n") }
+            }
+        }
+    }
+}
+
+@Composable
+private fun ProgressRow(entry: ProgressInHand, onChoose: (ProgressInHand) -> Unit) {
+    val kind = entry.card.kind
+    Row(
+        modifier = Modifier.fillMaxWidth(),
+        verticalAlignment = Alignment.CenterVertically,
+        horizontalArrangement = Arrangement.spacedBy(8.dp),
+    ) {
+        TrackChip(kind.track)
+        Column(modifier = Modifier.weight(1f)) {
+            Text(CatanText.progress(kind), fontWeight = FontWeight.Bold)
+            Text(CatanText.progressHelp(kind), style = MaterialTheme.typography.bodySmall)
+        }
+        if (entry.playable) {
+            Button(onClick = { onChoose(entry) }) { Text("Play") }
+        } else {
+            Text("Not now", style = MaterialTheme.typography.labelSmall)
+        }
+    }
+}
+
+// ---------------------------------------------------------------------------
+// Knights
+// ---------------------------------------------------------------------------
+
+/** What the knight on one crossing can do: wake, promote, move, chase the robber. */
+@Composable
+fun CatanKnightDialog(
+    state: CatanState,
+    vertex: Int,
+    actions: List<CatanMove>,
+    onDo: (CatanMove) -> Unit,
+    onMove: (Int) -> Unit,
+    onCancel: () -> Unit,
+) {
+    val knight = state.ck?.knights?.firstOrNull { it.vertex == vertex }
+    AlertDialog(
+        onDismissRequest = onCancel,
+        title = { Text(knight?.let { CatanText.knightName(it.level) } ?: "Knight") },
+        text = {
+            Column(verticalArrangement = Arrangement.spacedBy(8.dp)) {
+                if (knight != null) {
+                    val mood = when {
+                        !knight.active -> "Asleep. Waking it costs ${CatanText.ACTIVATE_COST}."
+                        knight.activatedTurn == state.turnNumber -> "Awake, but it woke this turn and cannot act yet."
+                        else -> "Awake and ready. It counts against the barbarians."
+                    }
+                    Text(mood, style = MaterialTheme.typography.bodySmall)
+                }
+                actions.forEach { move ->
+                    when (move) {
+                        is ActivateKnight ->
+                            Button(onClick = { onDo(move) }, modifier = Modifier.fillMaxWidth()) {
+                                Text("Wake (${CatanText.ACTIVATE_COST})")
+                            }
+
+                        is PromoteKnight ->
+                            Button(onClick = { onDo(move) }, modifier = Modifier.fillMaxWidth()) {
+                                Text("Promote (${CatanText.KNIGHT_COST})")
+                            }
+
+                        is MoveKnight ->
+                            OutlinedButton(onClick = { onMove(move.from) }, modifier = Modifier.fillMaxWidth()) {
+                                Text("Move along your roads")
+                            }
+
+                        is ChaseRobber ->
+                            OutlinedButton(onClick = { onDo(move) }, modifier = Modifier.fillMaxWidth()) {
+                                Text("Chase away the robber")
+                            }
+
+                        else -> Unit
+                    }
+                }
+                if (actions.isEmpty()) Text("Nothing to do with it right now.")
+            }
+        },
+        confirmButton = {},
+        dismissButton = { TextButton(onClick = onCancel) { Text("Close") } },
+    )
+}
+
+// ---------------------------------------------------------------------------
+// Chores that are answered in a dialog
+// ---------------------------------------------------------------------------
+
+/** Choose a colour of progress deck to draw from. */
+@Composable
+fun CatanPickDeckDialog(legal: List<CatanMove>, onPick: (PickDeck) -> Unit) {
+    val open = legal.filterIsInstance<PickDeck>()
+    AlertDialog(
+        onDismissRequest = {},
+        title = { Text("Draw a progress card") },
+        text = {
+            Column(verticalArrangement = Arrangement.spacedBy(8.dp)) {
+                Text("Catan held. You tied for the strongest defence, so choose any deck.")
+                open.forEach { pick ->
+                    Button(onClick = { onPick(pick) }, modifier = Modifier.fillMaxWidth()) {
+                        TrackChip(pick.track)
+                        Text("  ${CatanText.track(pick.track)}")
+                    }
+                }
+            }
+        },
+        confirmButton = {},
+    )
+}
+
+/** The hand is over its limit: give one progress card back. */
+@Composable
+fun CatanDropProgressDialog(hand: List<ProgressCard>, onDrop: (DropProgress) -> Unit) {
+    AlertDialog(
+        onDismissRequest = {},
+        title = { Text("Too many progress cards") },
+        text = {
+            Column(
+                modifier = Modifier.heightIn(max = 380.dp).verticalScroll(rememberScrollState()),
+                verticalArrangement = Arrangement.spacedBy(8.dp),
+            ) {
+                Text("You may keep four. Choose one to give back.")
+                hand.forEach { card ->
+                    OutlinedButton(onClick = { onDrop(DropProgress(card.id)) }, modifier = Modifier.fillMaxWidth()) {
+                        TrackChip(card.kind.track)
+                        Text("  ${CatanText.progress(card.kind)}")
+                    }
+                }
+            }
+        },
+        confirmButton = {},
+    )
+}
+
+/** The aqueduct pays: take any one resource. */
+@OptIn(ExperimentalLayoutApi::class)
+@Composable
+fun CatanAqueductDialog(legal: List<CatanMove>, onTake: (TakeAqueduct) -> Unit) {
+    AlertDialog(
+        onDismissRequest = {},
+        title = { Text("Aqueduct") },
+        text = {
+            Column(verticalArrangement = Arrangement.spacedBy(12.dp)) {
+                Text("The dice paid you nothing. Take any resource.")
+                FlowRow(
+                    horizontalArrangement = Arrangement.spacedBy(8.dp),
+                    verticalArrangement = Arrangement.spacedBy(8.dp),
+                ) {
+                    legal.filterIsInstance<TakeAqueduct>().forEach { take ->
+                        ResourceTile(resource = take.resource, count = 1, onClick = { onTake(take) })
+                    }
+                }
+            }
+        },
+        confirmButton = {},
+    )
+}
+
+/** A spy: these are the progress cards the other player holds; take one. */
+@Composable
+fun CatanSpyDialog(cards: List<ProgressCard>, legal: List<CatanMove>, onTake: (SpyTake) -> Unit) {
+    AlertDialog(
+        onDismissRequest = {},
+        title = { Text("Spy") },
+        text = {
+            Column(
+                modifier = Modifier.heightIn(max = 380.dp).verticalScroll(rememberScrollState()),
+                verticalArrangement = Arrangement.spacedBy(8.dp),
+            ) {
+                Text("Choose a card to take.")
+                cards.forEach { card ->
+                    val take = SpyTake(card.id)
+                    OutlinedButton(
+                        onClick = { onTake(take) },
+                        enabled = take in legal,
+                        modifier = Modifier.fillMaxWidth(),
+                    ) {
+                        TrackChip(card.kind.track)
+                        Text("  ${CatanText.progress(card.kind)}")
+                    }
+                }
+            }
+        },
+        confirmButton = {},
+    )
+}
+
+// ---------------------------------------------------------------------------
+// Trading in goods
+// ---------------------------------------------------------------------------
+
+private enum class GoodsTab { BANK, PLAYER }
+
+/**
+ * Trade with the bank at the best ratio each card has, or offer cards —
+ * commodities included — to one other player.
+ */
+@OptIn(ExperimentalLayoutApi::class)
+@Composable
+fun CatanGoodsTradeDialog(
+    state: CatanState,
+    seat: Int,
+    seats: CatanSeats,
+    legal: List<CatanMove>,
+    onBank: (GoodsBankTrade) -> Unit,
+    onOffer: (OfferGoods) -> Unit,
+    onCancel: () -> Unit,
+) {
+    var tab by remember { mutableStateOf(GoodsTab.BANK) }
+    var bankGive by remember { mutableStateOf<Good?>(null) }
+    var everyone by remember { mutableStateOf(true) }
+    var partner by remember { mutableStateOf<Int?>(null) }
+    var give by remember { mutableStateOf(emptyMap<Good, Int>()) }
+    var get by remember { mutableStateOf(emptyMap<Good, Int>()) }
+    val held = CatanCk.goodsOf(state, seat)
+
+    AlertDialog(
+        onDismissRequest = onCancel,
+        title = { Text(CatanText.TRADE) },
+        text = {
+            Column(
+                modifier = Modifier.heightIn(max = 460.dp).verticalScroll(rememberScrollState()),
+                verticalArrangement = Arrangement.spacedBy(12.dp),
+            ) {
+                Row(horizontalArrangement = Arrangement.spacedBy(8.dp)) {
+                    GoodsTabButton(CatanText.TRADE_WITH_BANK, tab == GoodsTab.BANK) { tab = GoodsTab.BANK }
+                    GoodsTabButton(CatanText.TRADE_WITH_PLAYER, tab == GoodsTab.PLAYER) { tab = GoodsTab.PLAYER }
+                }
+                if (tab == GoodsTab.BANK) {
+                    val trades = CatanInteraction.goodsBankTrades(legal)
+                    if (trades.isEmpty()) {
+                        Text("You do not hold enough of any one card to trade with the bank.")
+                    } else {
+                        Text("Give:", fontWeight = FontWeight.Bold)
+                        FlowRow(
+                            horizontalArrangement = Arrangement.spacedBy(8.dp),
+                            verticalArrangement = Arrangement.spacedBy(8.dp),
+                        ) {
+                            trades.keys.forEach { good ->
+                                val ratio = CatanCk.bankRatio(state, seat, good)
+                                Column(horizontalAlignment = Alignment.CenterHorizontally) {
+                                    GoodTile(good, ratio, selected = bankGive == good, onClick = { bankGive = good })
+                                    Text("$ratio : 1", style = MaterialTheme.typography.labelSmall)
+                                }
+                            }
+                        }
+                        val chosen = bankGive
+                        if (chosen != null && chosen in trades) {
+                            Text("Get one:", fontWeight = FontWeight.Bold)
+                            FlowRow(
+                                horizontalArrangement = Arrangement.spacedBy(8.dp),
+                                verticalArrangement = Arrangement.spacedBy(8.dp),
+                            ) {
+                                trades.getValue(chosen).forEach { good ->
+                                    GoodTile(good, 1, onClick = { onBank(GoodsBankTrade(chosen, good)) })
+                                }
+                            }
+                        }
+                    }
+                } else {
+                    Text("Offer to:", fontWeight = FontWeight.Bold)
+                    FlowRow(
+                        horizontalArrangement = Arrangement.spacedBy(8.dp),
+                        verticalArrangement = Arrangement.spacedBy(8.dp),
+                    ) {
+                        GoodsTabButton(CatanText.EVERYONE, everyone) {
+                            everyone = true
+                            partner = null
+                        }
+                        (0 until state.playerCount).filter { it != seat }.forEach { other ->
+                            GoodsTabButton(seats.label(other), !everyone && partner == other) {
+                                everyone = false
+                                partner = other
+                            }
+                        }
+                    }
+                    Text(CatanText.YOU_GIVE, fontWeight = FontWeight.Bold)
+                    GoodCounters(give, { held[it] ?: 0 }) { give = it }
+                    Text(CatanText.YOU_GET, fontWeight = FontWeight.Bold)
+                    GoodCounters(get, { 9 }) { get = it }
+                }
+            }
+        },
+        confirmButton = {
+            if (tab == GoodsTab.PLAYER) {
+                val to = if (everyone) null else partner
+                val giveCards = give.asGoods()
+                val getCards = get.asGoods()
+                val allowed = (everyone || partner != null) &&
+                    CatanInteraction.goodsOfferAllowed(state, seat, to, giveCards, getCards)
+                Button(
+                    onClick = { onOffer(OfferGoods(to, giveCards, getCards)) },
+                    enabled = allowed,
+                ) { Text(CatanText.SEND_OFFER) }
+            }
+        },
+        dismissButton = { TextButton(onClick = onCancel) { Text(CatanText.CANCEL) } },
+    )
+}
+
+@OptIn(ExperimentalLayoutApi::class)
+@Composable
+private fun GoodCounters(counts: Map<Good, Int>, limit: (Good) -> Int, onChange: (Map<Good, Int>) -> Unit) {
+    FlowRow(
+        horizontalArrangement = Arrangement.spacedBy(8.dp),
+        verticalArrangement = Arrangement.spacedBy(8.dp),
+    ) {
+        Good.entries.forEach { good ->
+            GoodCounter(
+                good = good,
+                count = counts[good] ?: 0,
+                max = limit(good),
+                onChange = { n -> onChange(counts + (good to n.coerceIn(0, limit(good)))) },
+            )
+        }
+    }
+}
+
+@Composable
+private fun GoodsTabButton(label: String, selected: Boolean, onClick: () -> Unit) {
+    if (selected) {
+        FilledTonalButton(onClick = onClick) { Text(label) }
+    } else {
+        OutlinedButton(onClick = onClick) { Text(label) }
+    }
+}
+
+/**
+ * A goods offer has reached the local player: accept it, decline it, or answer
+ * with different terms. The counter's two sides start as the offer turned around.
+ */
+@OptIn(ExperimentalLayoutApi::class)
+@Composable
+fun CatanGoodsTradeResponseDialog(
+    state: CatanState,
+    seat: Int,
+    offer: GoodsOffer,
+    seats: CatanSeats,
+    canAccept: Boolean,
+    onAccept: () -> Unit,
+    onDecline: () -> Unit,
+    onCounter: (CounterGoods) -> Unit,
+) {
+    var countering by remember(offer) { mutableStateOf(false) }
+    var give by remember(offer) { mutableStateOf(offer.get.groupingBy { it }.eachCount()) }
+    var get by remember(offer) { mutableStateOf(offer.give.groupingBy { it }.eachCount()) }
+
+    AlertDialog(
+        onDismissRequest = {},
+        title = { Text(if (countering) "Counter-offer" else "Trade offer") },
+        text = {
+            Column(
+                modifier = Modifier.heightIn(max = 460.dp).verticalScroll(rememberScrollState()),
+                verticalArrangement = Arrangement.spacedBy(8.dp),
+            ) {
+                Text(
+                    "${seats.label(offer.by)} offers ${CatanText.goods(offer.give)} to " +
+                        "${if (offer.to == null) "the table" else "you"} for ${CatanText.goods(offer.get)}",
+                )
+                if (countering) {
+                    Text(CatanText.YOU_GIVE, fontWeight = FontWeight.Bold)
+                    GoodCounters(give, { CatanCk.goodsOf(state, seat)[it] ?: 0 }) { give = it }
+                    Text(CatanText.YOU_GET, fontWeight = FontWeight.Bold)
+                    GoodCounters(get, { CatanCk.goodsOf(state, offer.by)[it] ?: 0 }) { get = it }
+                } else if (!canAccept) {
+                    Text(
+                        "You cannot accept this: one side no longer holds the cards.",
+                        style = MaterialTheme.typography.bodySmall,
+                    )
+                }
+            }
+        },
+        confirmButton = {
+            if (countering) {
+                val move = CounterGoods(give.asGoods(), get.asGoods())
+                Button(
+                    onClick = { onCounter(move) },
+                    enabled = CatanInteraction.goodsCounterAllowed(state, seat, move.give, move.get),
+                ) { Text(CatanText.SEND_COUNTER) }
+            } else {
+                Button(onClick = onAccept, enabled = canAccept) { Text(CatanText.ACCEPT) }
+            }
+        },
+        dismissButton = {
+            Row(horizontalArrangement = Arrangement.spacedBy(4.dp)) {
+                if (countering) {
+                    TextButton(onClick = { countering = false }) { Text(CatanText.CANCEL) }
+                } else {
+                    TextButton(onClick = { countering = true }) { Text(CatanText.COUNTER) }
+                }
+                TextButton(onClick = onDecline) { Text(CatanText.DECLINE) }
+            }
+        },
+    )
+}
+
+/** The offerer's choice once nobody accepted a goods offer: take a counter-offer, or none. */
+@Composable
+fun CatanGoodsCounterChoiceDialog(
+    counters: List<GoodsCounter>,
+    seats: CatanSeats,
+    onTake: (AcceptCounter) -> Unit,
+    onNoDeal: () -> Unit,
+) {
+    AlertDialog(
+        onDismissRequest = {},
+        title = { Text("Counter-offers") },
+        text = {
+            Column(
+                modifier = Modifier.heightIn(max = 460.dp).verticalScroll(rememberScrollState()),
+                verticalArrangement = Arrangement.spacedBy(8.dp),
+            ) {
+                if (counters.isEmpty()) Text("None of the counter-offers can be met any more.")
+                counters.forEach { counter ->
+                    Column(verticalArrangement = Arrangement.spacedBy(4.dp)) {
+                        Text(
+                            "${seats.label(counter.by)} would give ${CatanText.goods(counter.give)} " +
+                                "for ${CatanText.goods(counter.get)}",
+                        )
+                        Button(onClick = { onTake(AcceptCounter(counter.by)) }) { Text(CatanText.ACCEPT) }
+                    }
+                }
+            }
+        },
+        confirmButton = { TextButton(onClick = onNoDeal) { Text(CatanText.NO_DEAL) } },
+    )
+}

app/src/main/java/org/prolibertate/games/ui/game/catan/CatanDialogs.kt

@@ -1,5 +1,6 @@
 package org.prolibertate.games.ui.game.catan
 
+import org.prolibertate.games.ui.LocalEndGameHandle
 import androidx.compose.foundation.layout.Arrangement
 import androidx.compose.foundation.layout.Column
 import androidx.compose.foundation.layout.ExperimentalLayoutApi
@@ -35,6 +36,9 @@ import org.prolibertate.games.game.catan.DevCardType
 import org.prolibertate.games.game.catan.Discard
 import org.prolibertate.games.game.catan.MaritimeTrade
 import org.prolibertate.games.game.catan.OfferTrade
+import org.prolibertate.games.game.catan.TradeCounter
+import org.prolibertate.games.game.catan.CounterTrade
+import org.prolibertate.games.game.catan.AcceptCounter
 import org.prolibertate.games.game.catan.PlayKnight
 import org.prolibertate.games.game.catan.PlayRoadBuilding
 import org.prolibertate.games.game.catan.Resource
@@ -312,6 +316,7 @@ fun CatanTradeDialog(
 ) {
     var tab by remember { mutableStateOf(TradeTab.BANK) }
     var bankGive by remember { mutableStateOf<Resource?>(null) }
+    var everyone by remember { mutableStateOf(true) }
     var partner by remember { mutableStateOf<Int?>(null) }
     var give by remember { mutableStateOf(emptyMap<Resource, Int>()) }
     var get by remember { mutableStateOf(emptyMap<Resource, Int>()) }
@@ -371,9 +376,16 @@ fun CatanTradeDialog(
                     }
                 } else {
                     Text("Offer to:", fontWeight = FontWeight.Bold)
-                    Row(horizontalArrangement = Arrangement.spacedBy(8.dp)) {
+                    FlowRow(
+                        horizontalArrangement = Arrangement.spacedBy(8.dp),
+                        verticalArrangement = Arrangement.spacedBy(8.dp),
+                    ) {
+                        TabButton(CatanText.EVERYONE, everyone) { everyone = true; partner = null }
                         (0 until state.playerCount).filter { it != seat }.forEach { other ->
-                            TabButton(seats.label(other), partner == other) { partner = other }
+                            TabButton(seats.label(other), !everyone && partner == other) {
+                                everyone = false
+                                partner = other
+                            }
                         }
                     }
                     Text(CatanText.YOU_GIVE, fontWeight = FontWeight.Bold)
@@ -389,13 +401,13 @@ fun CatanTradeDialog(
         },
         confirmButton = {
             if (tab == TradeTab.PLAYER) {
-                val to = partner
+                val to = if (everyone) null else partner
                 val giveCards = give.asCards()
                 val getCards = get.asCards()
-                val allowed = to != null &&
+                val allowed = (everyone || partner != null) &&
                     CatanInteraction.offerAllowed(state, seat, to, giveCards, getCards)
                 Button(
-                    onClick = { if (to != null) onOffer(OfferTrade(to, giveCards, getCards)) },
+                    onClick = { onOffer(OfferTrade(to, giveCards, getCards)) },
                     enabled = allowed,
                 ) { Text(CatanText.SEND_OFFER) }
             }
@@ -435,29 +447,57 @@ private fun TabButton(label: String, selected: Boolean, onClick: () -> Unit) {
     }
 }
 
-/** Another player has offered the local player a trade. */
+/**
+ * Another player has put an offer to the local player (alone, or as one of the
+ * table). Accept, decline, or — via a second step — answer with different terms.
+ */
+@OptIn(ExperimentalLayoutApi::class)
 @Composable
 fun CatanTradeResponseDialog(
+    state: CatanState,
+    seat: Int,
     offer: TradeOffer,
     seats: CatanSeats,
     canAccept: Boolean,
     onAccept: () -> Unit,
     onDecline: () -> Unit,
+    onCounter: (CounterTrade) -> Unit,
 ) {
+    var countering by remember(offer) { mutableStateOf(false) }
+    // What we would give the offerer, and what we would ask of them.
+    var give by remember(offer) { mutableStateOf(offer.get.groupingBy { it }.eachCount()) }
+    var get by remember(offer) { mutableStateOf(offer.give.groupingBy { it }.eachCount()) }
+
     AlertDialog(
         onDismissRequest = {},
-        title = { Text("Trade offer") },
+        title = { Text(if (countering) "Counter-offer" else "Trade offer") },
         text = {
-            Column(verticalArrangement = Arrangement.spacedBy(6.dp)) {
+            Column(
+                modifier = Modifier.heightIn(max = 460.dp).verticalScroll(rememberScrollState()),
+                verticalArrangement = Arrangement.spacedBy(8.dp),
+            ) {
                 Text(
                     CatanText.tradeSummary(
                         by = seats.label(offer.by),
-                        to = "you",
+                        to = if (offer.to == null) "the table" else "you",
                         give = offer.give,
                         get = offer.get,
                     ),
                 )
-                if (!canAccept) {
+                if (countering) {
+                    Text(CatanText.YOU_GIVE, fontWeight = FontWeight.Bold)
+                    CounterRow(
+                        counts = give,
+                        limit = { state.resources[seat][it] ?: 0 },
+                        onChange = { give = it },
+                    )
+                    Text(CatanText.YOU_GET, fontWeight = FontWeight.Bold)
+                    CounterRow(
+                        counts = get,
+                        limit = { state.resources[offer.by][it] ?: 0 },
+                        onChange = { get = it },
+                    )
+                } else if (!canAccept) {
                     Text(
                         "You cannot accept this: one side no longer holds the cards.",
                         style = MaterialTheme.typography.bodySmall,
@@ -465,8 +505,58 @@ fun CatanTradeResponseDialog(
                 }
             }
         },
-        confirmButton = { Button(onClick = onAccept, enabled = canAccept) { Text(CatanText.ACCEPT) } },
-        dismissButton = { TextButton(onClick = onDecline) { Text(CatanText.DECLINE) } },
+        confirmButton = {
+            if (countering) {
+                val move = CounterTrade(give.asCards(), get.asCards())
+                Button(
+                    onClick = { onCounter(move) },
+                    enabled = CatanInteraction.counterAllowed(state, seat, move.give, move.get),
+                ) { Text(CatanText.SEND_COUNTER) }
+            } else {
+                Button(onClick = onAccept, enabled = canAccept) { Text(CatanText.ACCEPT) }
+            }
+        },
+        dismissButton = {
+            Row(horizontalArrangement = Arrangement.spacedBy(4.dp)) {
+                if (countering) {
+                    TextButton(onClick = { countering = false }) { Text(CatanText.CANCEL) }
+                } else {
+                    TextButton(onClick = { countering = true }) { Text(CatanText.COUNTER) }
+                }
+                TextButton(onClick = onDecline) { Text(CatanText.DECLINE) }
+            }
+        },
+    )
+}
+
+/** The offerer's choice once nobody accepted: take a counter-offer, or none. */
+@Composable
+fun CatanCounterChoiceDialog(
+    counters: List<TradeCounter>,
+    seats: CatanSeats,
+    onTake: (AcceptCounter) -> Unit,
+    onNoDeal: () -> Unit,
+) {
+    AlertDialog(
+        onDismissRequest = {},
+        title = { Text("Counter-offers") },
+        text = {
+            Column(
+                modifier = Modifier.heightIn(max = 460.dp).verticalScroll(rememberScrollState()),
+                verticalArrangement = Arrangement.spacedBy(8.dp),
+            ) {
+                if (counters.isEmpty()) {
+                    Text("None of the counter-offers can be met any more.")
+                }
+                counters.forEach { counter ->
+                    Column(verticalArrangement = Arrangement.spacedBy(4.dp)) {
+                        Text(CatanText.counterSummary(seats.label(counter.by), counter.give, counter.get))
+                        Button(onClick = { onTake(AcceptCounter(counter.by)) }) { Text(CatanText.ACCEPT) }
+                    }
+                }
+            }
+        },
+        confirmButton = { TextButton(onClick = onNoDeal) { Text(CatanText.NO_DEAL) } },
     )
 }
 
@@ -514,7 +604,12 @@ fun CatanEndGameDialog(onEnd: () -> Unit, onKeepPlaying: () -> Unit) {
                     "at the table is told you have left.",
             )
         },
-        confirmButton = { TextButton(onClick = onEnd) { Text("End the game") } },
+        confirmButton = {
+            // Ending a game on purpose also forgets the saved position: only
+            // leaving the table keeps it to be picked up again.
+            val handle = LocalEndGameHandle.current
+            TextButton(onClick = { handle.end(); onEnd() }) { Text("End the game") }
+        },
         dismissButton = { TextButton(onClick = onKeepPlaying) { Text("Keep playing") } },
     )
 }

app/src/main/java/org/prolibertate/games/ui/game/catan/CatanHud.kt

@@ -0,0 +1,458 @@
+package org.prolibertate.games.ui.game.catan
+
+import androidx.compose.foundation.background
+import androidx.compose.foundation.border
+import androidx.compose.foundation.clickable
+import androidx.compose.foundation.gestures.detectDragGestures
+import androidx.compose.foundation.gestures.detectTransformGestures
+import androidx.compose.foundation.layout.Arrangement
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.horizontalScroll
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.height
+import androidx.compose.foundation.layout.width
+import androidx.compose.foundation.rememberScrollState
+import androidx.compose.material3.Surface
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.foundation.layout.Row
+import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.layout.size
+import androidx.compose.foundation.shape.CircleShape
+import androidx.compose.foundation.shape.RoundedCornerShape
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.Text
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableFloatStateOf
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.runtime.rememberUpdatedState
+import androidx.compose.runtime.setValue
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.draw.clip
+import androidx.compose.ui.geometry.Offset
+import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.graphics.graphicsLayer
+import androidx.compose.ui.input.pointer.pointerInput
+import androidx.compose.ui.layout.LayoutCoordinates
+import androidx.compose.ui.layout.onGloballyPositioned
+import androidx.compose.ui.text.font.FontWeight
+import androidx.compose.ui.unit.Dp
+import androidx.compose.ui.unit.dp
+import androidx.compose.ui.unit.sp
+
+/*
+ * The heads-up display pieces of the landscape Katan screen: the controls the
+ * Catan Universe match screen uses (see docs/RE-catan-universe.md), redrawn in
+ * 2D. Stateless, like everything in CatanPanels.kt: values in, lambdas out.
+ */
+
+/** A round HUD button: a glyph or short word, optionally with a one-word caption. */
+@Composable
+fun HudRoundButton(
+    glyph: String,
+    modifier: Modifier = Modifier,
+    caption: String? = null,
+    enabled: Boolean = true,
+    primary: Boolean = false,
+    tint: Color = Color.Unspecified,
+    diameter: Dp = 56.dp,
+    onClick: () -> Unit,
+) {
+    val container = when {
+        tint != Color.Unspecified -> tint
+        primary -> MaterialTheme.colorScheme.primary
+        else -> MaterialTheme.colorScheme.secondaryContainer
+    }
+    val ink = if (primary || tint != Color.Unspecified) Color.White else MaterialTheme.colorScheme.onSecondaryContainer
+    Column(modifier, horizontalAlignment = Alignment.CenterHorizontally) {
+        Box(
+            modifier = Modifier
+                .size(diameter)
+                .clip(CircleShape)
+                .background(container.copy(alpha = if (enabled) 1f else 0.35f))
+                .border(2.dp, Color(0x55000000), CircleShape)
+                .then(if (enabled) Modifier.clickable(onClick = onClick) else Modifier),
+            contentAlignment = Alignment.Center,
+        ) {
+            Text(glyph, color = ink.copy(alpha = if (enabled) 1f else 0.6f), fontSize = 18.sp, fontWeight = FontWeight.Bold)
+        }
+        // Always laid out, so the button column never changes height.
+        Text(caption ?: " ", fontSize = 10.sp, maxLines = 1)
+    }
+}
+
+/**
+ * The left-hand build column: one icon per piece. **Drag one onto the board** and
+ * release over a lit spot to stage it; or tap to arm the board and tap a spot. The
+ * column reports pointer positions in window coordinates so the screen can find the
+ * spot under the finger whatever the board's zoom and pan.
+ */
+@Composable
+fun HudBuildColumn(
+    kinds: List<BuildKind>,
+    canBuild: Set<BuildKind>,
+    armed: BuildKind?,
+    modifier: Modifier = Modifier,
+    onTap: (BuildKind) -> Unit,
+    onDragStart: (BuildKind, Offset) -> Unit,
+    onDrag: (Offset) -> Unit,
+    onDragEnd: () -> Unit,
+) {
+    Column(modifier, verticalArrangement = Arrangement.spacedBy(3.dp), horizontalAlignment = Alignment.CenterHorizontally) {
+        kinds.forEach { kind ->
+            BuildChip(kind, enabled = kind in canBuild, armed = armed == kind, onTap, onDragStart, onDrag, onDragEnd)
+        }
+    }
+}
+
+@Composable
+private fun BuildChip(
+    kind: BuildKind,
+    enabled: Boolean,
+    armed: Boolean,
+    onTap: (BuildKind) -> Unit,
+    onDragStart: (BuildKind, Offset) -> Unit,
+    onDrag: (Offset) -> Unit,
+    onDragEnd: () -> Unit,
+) {
+    var coords by remember { mutableStateOf<LayoutCoordinates?>(null) }
+    val start by rememberUpdatedState(onDragStart)
+    val move by rememberUpdatedState(onDrag)
+    val end by rememberUpdatedState(onDragEnd)
+    val tap by rememberUpdatedState(onTap)
+    val shape = RoundedCornerShape(12.dp)
+    Column(horizontalAlignment = Alignment.CenterHorizontally) {
+        Box(
+            modifier = Modifier
+                .size(46.dp)
+                .clip(shape)
+                .background(
+                    when {
+                        armed -> MaterialTheme.colorScheme.primary
+                        else -> MaterialTheme.colorScheme.secondaryContainer.copy(alpha = if (enabled) 1f else 0.35f)
+                    },
+                )
+                .border(2.dp, Color(0x55000000), shape)
+                .onGloballyPositioned { coords = it }
+                .pointerInput(enabled, kind) {
+                    if (!enabled) return@pointerInput
+                    detectDragGestures(
+                        onDragStart = { local ->
+                            coords?.localToWindow(local)?.let { start(kind, it) }
+                        },
+                        onDrag = { change, _ ->
+                            change.consume()
+                            coords?.localToWindow(change.position)?.let { move(it) }
+                        },
+                        onDragEnd = { end() },
+                        onDragCancel = { end() },
+                    )
+                }
+                .then(if (enabled) Modifier.clickable { tap(kind) } else Modifier),
+            contentAlignment = Alignment.Center,
+        ) {
+            Text(
+                CatanHudGlyphs.of(kind),
+                fontSize = 22.sp,
+                color = if (armed) Color.White else MaterialTheme.colorScheme.onSecondaryContainer,
+            )
+        }
+        Text(CatanHudGlyphs.label(kind), fontSize = 10.sp, maxLines = 1)
+    }
+}
+
+/** Glyphs and captions of the build column. Kept apart so the art can be swapped for drawables. */
+object CatanHudGlyphs {
+    fun of(kind: BuildKind): String = when (kind) {
+        BuildKind.ROAD -> "━"
+        BuildKind.SETTLEMENT -> "⌂"
+        BuildKind.CITY -> "▲"
+        BuildKind.WALL -> "▦"
+        BuildKind.KNIGHT -> "♞"
+    }
+
+    fun label(kind: BuildKind): String = when (kind) {
+        BuildKind.ROAD -> CatanText.ROAD
+        BuildKind.SETTLEMENT -> CatanText.SETTLEMENT
+        BuildKind.CITY -> CatanText.CITY
+        BuildKind.WALL -> CatanText.WALL
+        BuildKind.KNIGHT -> CatanText.KNIGHT
+    }
+}
+
+/** ✓ beside ✗: confirm or cancel a staged placement. Always laid out; enabled only while something is staged. */
+@Composable
+fun HudConfirmButtons(
+    staged: Boolean,
+    modifier: Modifier = Modifier,
+    onConfirm: () -> Unit,
+    onCancel: () -> Unit,
+) {
+    Row(modifier, horizontalArrangement = Arrangement.spacedBy(6.dp), verticalAlignment = Alignment.Bottom) {
+        HudRoundButton("✓", caption = CatanText.CONFIRM_BUILD, enabled = staged, tint = Color(0xFF2E7D32), diameter = 48.dp, onClick = onConfirm)
+        HudRoundButton("✕", caption = CatanText.CANCEL_BUILD, enabled = staged, tint = Color(0xFFC62828), diameter = 48.dp, onClick = onCancel)
+    }
+}
+
+/**
+ * Pan with one finger, pinch to zoom, like the Universe board camera. The content
+ * is drawn through a graphics layer, so taps inside it arrive already in the
+ * content's own coordinates and the board's hit-testing needs no changes.
+ */
+@Composable
+fun ZoomPanBox(
+    modifier: Modifier = Modifier,
+    minScale: Float = 1f,
+    maxScale: Float = 3f,
+    content: @Composable () -> Unit,
+) {
+    var scale by remember { mutableFloatStateOf(1f) }
+    var offset by remember { mutableStateOf(Offset.Zero) }
+    Box(
+        modifier = modifier
+            .clip(RoundedCornerShape(0.dp))
+            .pointerInput(Unit) {
+                detectTransformGestures { centroid, pan, zoom, _ ->
+                    val newScale = (scale * zoom).coerceIn(minScale, maxScale)
+                    val centre = Offset(size.width / 2f, size.height / 2f)
+                    // The content point under the fingers stays under them while zooming; then pan.
+                    val world = (centroid - centre - offset) / scale
+                    val next = centroid - centre - world * newScale + pan
+                    val maxX = size.width * (newScale - 1f) / 2f
+                    val maxY = size.height * (newScale - 1f) / 2f
+                    offset = Offset(next.x.coerceIn(-maxX, maxX), next.y.coerceIn(-maxY, maxY))
+                    scale = newScale
+                }
+            },
+    ) {
+        Box(
+            Modifier
+                .fillMaxSize()
+                .graphicsLayer {
+                    scaleX = scale
+                    scaleY = scale
+                    translationX = offset.x
+                    translationY = offset.y
+                },
+            contentAlignment = Alignment.Center,
+        ) { content() }
+    }
+}
+
+/** A small caption pill, for the drag hint and the staged-move text. */
+@Composable
+fun HudPill(text: String, modifier: Modifier = Modifier) {
+    Text(
+        text,
+        color = Color.White,
+        fontSize = 12.sp,
+        maxLines = 1,
+        modifier = modifier
+            .clip(RoundedCornerShape(50))
+            .background(Color(0xCC000000))
+            .padding(horizontal = 12.dp, vertical = 4.dp),
+    )
+}
+
+/**
+ * The landscape screen, laid out like the Catan Universe match view:
+ *
+ * ```
+ * ┌ player strip ───────────────────────────────────────────────┐
+ * │ prompt + dice                                               │
+ * │ [build]            the island (pinch / pan)        [✓] [✕]  │
+ * │ [column]                                                    │
+ * │ [log]       ┌ your cards ┐                  [buy][play] [⇄][●]│
+ * └─────────────┴────────────┴───────────────────────────────────┘
+ * ```
+ *
+ * Everything here is wiring around the existing panels; the island is handed in as [board].
+ */
+@Composable
+fun CatanHud(
+    state: org.prolibertate.games.game.catan.CatanState,
+    seats: CatanSeats,
+    style: CatanStyle,
+    actions: CatanActions,
+    prompt: String,
+    notice: String?,
+    legal: List<org.prolibertate.games.game.catan.CatanMove>,
+    localSeat: Int,
+    targets: BoardTargets,
+    pointsOf: (Int) -> Int,
+    staged: org.prolibertate.games.game.catan.CatanMove?,
+    dragKind: BuildKind?,
+    dragAt: Offset?,
+    showLog: Boolean,
+    boardCoords: LayoutCoordinates?,
+    building: BuildKind?,
+    onBoardCoords: (LayoutCoordinates) -> Unit,
+    onToggleLog: () -> Unit,
+    onArm: (BuildKind) -> Unit,
+    onDragStart: (BuildKind, Offset) -> Unit,
+    onDrag: (Offset) -> Unit,
+    onDragEnd: () -> Unit,
+    onConfirm: () -> Unit,
+    onCancelStaged: () -> Unit,
+    onRoll: () -> Unit,
+    onEndTurn: () -> Unit,
+    onEndFreeRoads: () -> Unit,
+    onEndSmith: () -> Unit,
+    onRepickSetup: () -> Unit,
+    onBuyCard: () -> Unit,
+    onPlayCard: () -> Unit,
+    onTrade: () -> Unit,
+    onImprove: () -> Unit,
+    onProgress: () -> Unit,
+    board: @Composable (Modifier) -> Unit,
+) {
+    Column(Modifier.fillMaxSize(), verticalArrangement = Arrangement.spacedBy(2.dp)) {
+        HudPlayerStrip(state, seats, pointsOf, style)
+        Box(Modifier.weight(1f).fillMaxWidth()) {
+            // The island fills the whole area; controls float over its sea margin.
+            ZoomPanBox(Modifier.fillMaxSize().padding(start = 64.dp, end = 64.dp, top = 30.dp, bottom = 44.dp)) {
+                board(Modifier.onGloballyPositioned(onBoardCoords))
+            }
+
+            // What is going on, and the dice. Two lines, always.
+            Row(
+                Modifier.align(Alignment.TopCenter).padding(horizontal = 64.dp)
+                    .clip(RoundedCornerShape(10.dp))
+                    .background(MaterialTheme.colorScheme.surface.copy(alpha = 0.8f))
+                    .padding(horizontal = 8.dp, vertical = 1.dp),
+                verticalAlignment = Alignment.CenterVertically,
+                horizontalArrangement = Arrangement.spacedBy(8.dp),
+            ) {
+                Text(
+                    text = notice ?: prompt,
+                    style = MaterialTheme.typography.bodySmall,
+                    color = if (notice != null) MaterialTheme.colorScheme.error else Color.Unspecified,
+                    minLines = 2,
+                    maxLines = 2,
+                    modifier = Modifier.weight(1f),
+                )
+                CatanDice(state.lastDice, ck = state.isCk, event = state.ck?.eventDie)
+            }
+
+            // Left: pieces to drag onto the island.
+            HudBuildColumn(
+                kinds = actions.buildKinds,
+                canBuild = actions.canBuild,
+                armed = building,
+                modifier = Modifier.align(Alignment.CenterStart).padding(start = 6.dp),
+                onTap = onArm,
+                onDragStart = onDragStart,
+                onDrag = onDrag,
+                onDragEnd = onDragEnd,
+            )
+
+            // Right, middle: the card actions.
+            Column(
+                Modifier.align(Alignment.CenterEnd).padding(end = 6.dp),
+                verticalArrangement = Arrangement.spacedBy(4.dp),
+                horizontalAlignment = Alignment.CenterHorizontally,
+            ) {
+                if (actions.ck) {
+                    HudRoundButton("⬆", caption = CatanText.IMPROVE, enabled = actions.canImprove, diameter = 44.dp, onClick = onImprove)
+                    HudRoundButton("🂠", caption = CatanText.CARDS_SHORT, enabled = actions.canPlayProgress, diameter = 44.dp, onClick = onProgress)
+                } else {
+                    HudRoundButton("＋", caption = CatanText.BUY_SHORT, enabled = actions.canBuyCard, diameter = 44.dp, onClick = onBuyCard)
+                    HudRoundButton("🂠", caption = CatanText.CARDS_SHORT, enabled = actions.canPlayCard, diameter = 44.dp, onClick = onPlayCard)
+                }
+            }
+
+            // Bottom centre: your cards.
+            Box(
+                Modifier.align(Alignment.BottomCenter).padding(bottom = 4.dp, start = 80.dp, end = 270.dp)
+                    .clip(RoundedCornerShape(12.dp))
+                    .background(MaterialTheme.colorScheme.surface.copy(alpha = 0.85f))
+                    .horizontalScroll(rememberScrollState())
+                    .padding(6.dp),
+            ) { CatanHand(state, localSeat) }
+
+            // Bottom left: the log.
+            Column(Modifier.align(Alignment.BottomStart).padding(start = 6.dp, bottom = 4.dp)) {
+                if (showLog) {
+                    Surface(
+                        modifier = Modifier.padding(bottom = 6.dp),
+                        shape = RoundedCornerShape(12.dp),
+                        color = MaterialTheme.colorScheme.surface.copy(alpha = 0.92f),
+                        tonalElevation = 4.dp,
+                    ) {
+                        CatanLog(state, Modifier.padding(8.dp).height(150.dp).width(260.dp))
+                    }
+                }
+                HudRoundButton("☰", caption = CatanText.LOG_BUTTON, diameter = 40.dp, onClick = onToggleLog)
+            }
+
+            // Bottom right: place / cancel a lined-up piece, trade, and the turn button.
+            Row(
+                Modifier.align(Alignment.BottomEnd).padding(end = 6.dp, bottom = 4.dp),
+                horizontalArrangement = Arrangement.spacedBy(6.dp),
+                verticalAlignment = Alignment.Bottom,
+            ) {
+                HudConfirmButtons(staged = staged != null, onConfirm = onConfirm, onCancel = onCancelStaged)
+                HudRoundButton("⇄", caption = CatanText.TRADE, enabled = actions.canTrade, diameter = 48.dp, onClick = onTrade)
+                PrimaryTurnButton(actions, onRoll, onEndTurn, onEndFreeRoads, onEndSmith, onRepickSetup)
+            }
+
+            if (dragKind != null && dragAt == null) HudPill(CatanText.DRAG_HINT, Modifier.align(Alignment.TopCenter))
+        }
+    }
+}
+
+/** The one big button: roll, end the turn, finish roads, or step back from a setup choice. */
+@Composable
+private fun PrimaryTurnButton(
+    actions: CatanActions,
+    onRoll: () -> Unit,
+    onEndTurn: () -> Unit,
+    onEndFreeRoads: () -> Unit,
+    onEndSmith: () -> Unit,
+    onRepickSetup: () -> Unit,
+) {
+    val (glyph, caption, enabled, click) = when {
+        actions.canRoll -> Quad("🎲", CatanText.ROLL_SHORT, true, onRoll)
+        actions.canEndFreeRoads -> Quad("✔", CatanText.DONE_SHORT, true, onEndFreeRoads)
+        actions.canEndSmith -> Quad("✔", CatanText.DONE_SHORT, true, onEndSmith)
+        actions.canRepickSetup -> Quad("↺", CatanText.CANCEL, true, onRepickSetup)
+        else -> Quad("➜", CatanText.END_SHORT, actions.canEndTurn, onEndTurn)
+    }
+    HudRoundButton(glyph, caption = caption, enabled = enabled, primary = true, diameter = 72.dp, onClick = click)
+}
+
+private data class Quad(val glyph: String, val caption: String, val enabled: Boolean, val click: () -> Unit)
+
+/** Everyone's colour, name, points and card count in one thin row across the top. */
+@Composable
+private fun HudPlayerStrip(
+    state: org.prolibertate.games.game.catan.CatanState,
+    seats: CatanSeats,
+    pointsOf: (Int) -> Int,
+    style: CatanStyle,
+) {
+    Row(Modifier.fillMaxWidth().padding(horizontal = 6.dp, vertical = 2.dp), horizontalArrangement = Arrangement.spacedBy(6.dp)) {
+        (0 until state.playerCount).forEach { seat ->
+            val onTurn = seat == state.turn
+            val shape = RoundedCornerShape(10.dp)
+            Row(
+                Modifier.weight(1f)
+                    .clip(shape)
+                    .background(MaterialTheme.colorScheme.surfaceVariant)
+                    .border(if (onTurn) 2.dp else 1.dp, if (onTurn) MaterialTheme.colorScheme.primary else Color(0x33000000), shape)
+                    .padding(horizontal = 8.dp, vertical = 4.dp),
+                verticalAlignment = Alignment.CenterVertically,
+                horizontalArrangement = Arrangement.spacedBy(6.dp),
+            ) {
+                Box(
+                    Modifier.size(14.dp).clip(CircleShape).background(style.seats[seat]).border(1.dp, style.pieceOutline, CircleShape),
+                )
+                Text(seats.label(seat), fontSize = 12.sp, fontWeight = FontWeight.Bold, maxLines = 1, modifier = Modifier.weight(1f))
+                Text("${pointsOf(seat)} VP · ${state.resourceCount(seat)}🂠", fontSize = 12.sp, maxLines = 1)
+            }
+        }
+    }
+}

app/src/main/java/org/prolibertate/games/ui/game/catan/CatanInteraction.kt

@@ -1,43 +1,101 @@
 package org.prolibertate.games.ui.game.catan
 
+import org.prolibertate.games.game.catan.AcceptCounter
 import org.prolibertate.games.game.catan.AcceptTrade
+import org.prolibertate.games.game.catan.ActivateKnight
 import org.prolibertate.games.game.catan.BuildCity
 import org.prolibertate.games.game.catan.BuildRoad
 import org.prolibertate.games.game.catan.BuildSettlement
+import org.prolibertate.games.game.catan.BuildWall
 import org.prolibertate.games.game.catan.BuyDevCard
+import org.prolibertate.games.game.catan.BuyImprovement
 import org.prolibertate.games.game.catan.CatanBoard
 import org.prolibertate.games.game.catan.CatanMove
 import org.prolibertate.games.game.catan.CatanPhase
 import org.prolibertate.games.game.catan.CatanRules
 import org.prolibertate.games.game.catan.CatanState
+import org.prolibertate.games.game.catan.ChaseRobber
+import org.prolibertate.games.game.catan.Chore
+import org.prolibertate.games.game.catan.CounterTrade
 import org.prolibertate.games.game.catan.DeclineTrade
 import org.prolibertate.games.game.catan.DevCard
 import org.prolibertate.games.game.catan.DevCardType
 import org.prolibertate.games.game.catan.Discard
 import org.prolibertate.games.game.catan.EndFreeRoads
+import org.prolibertate.games.game.catan.EndSmith
 import org.prolibertate.games.game.catan.EndTurn
+import org.prolibertate.games.game.catan.CounterGoods
+import org.prolibertate.games.game.catan.GoodsBankTrade
+import org.prolibertate.games.game.catan.GoodsCounter
+import org.prolibertate.games.game.catan.Good
 import org.prolibertate.games.game.catan.HexCoord
+import org.prolibertate.games.game.catan.HireKnight
 import org.prolibertate.games.game.catan.MaritimeTrade
+import org.prolibertate.games.game.catan.MoveKnight
 import org.prolibertate.games.game.catan.MoveRobber
+import org.prolibertate.games.game.catan.OfferGoods
 import org.prolibertate.games.game.catan.OfferTrade
+import org.prolibertate.games.game.catan.PillageCity
+import org.prolibertate.games.game.catan.PlaceKnight
+import org.prolibertate.games.game.catan.PlaceMetropolis
+import org.prolibertate.games.game.catan.TradeCounter
 import org.prolibertate.games.game.catan.PlayKnight
 import org.prolibertate.games.game.catan.PlayMonopoly
+import org.prolibertate.games.game.catan.PlayProgress
 import org.prolibertate.games.game.catan.PlayRoadBuilding
 import org.prolibertate.games.game.catan.PlayYearOfPlenty
+import org.prolibertate.games.game.catan.ProgressCard
+import org.prolibertate.games.game.catan.ProgressType
+import org.prolibertate.games.game.catan.PromoteKnight
+import org.prolibertate.games.game.catan.RelocateKnight
+import org.prolibertate.games.game.catan.RemoveKnight
 import org.prolibertate.games.game.catan.Resource
 import org.prolibertate.games.game.catan.RollDice
 import org.prolibertate.games.game.catan.SetupPlace
+import org.prolibertate.games.game.catan.Track
 
-/** What a player can ask to build by tapping the board. */
-enum class BuildKind { ROAD, SETTLEMENT, CITY }
+/**
+ * What a player can ask to build by tapping the board. Wall and Knight exist
+ * only in Cities & Knights; the base game's build menu lists the first three.
+ */
+enum class BuildKind {
+    ROAD, SETTLEMENT, CITY, WALL, KNIGHT;
 
-/** The parts of the board the player may tap right now. Everything else is inert. */
+    companion object {
+        val BASE: List<BuildKind> = listOf(ROAD, SETTLEMENT, CITY)
+    }
+}
+
+/**
+ * The parts of the board the player may tap right now. Everything else is inert.
+ * [knights] are crossings holding one of the player's own knights that can do
+ * something this turn: tapping one opens its menu.
+ */
 data class BoardTargets(
     val vertices: Set<Int> = emptySet(),
     val edges: Set<Int> = emptySet(),
     val hexes: Set<Int> = emptySet(),
+    val knights: Set<Int> = emptySet(),
+    /** The player's other knights: tappable for their menu, but with nothing to do, so not ringed. */
+    val idleKnights: Set<Int> = emptySet(),
 ) {
-    val isEmpty: Boolean get() = vertices.isEmpty() && edges.isEmpty() && hexes.isEmpty()
+    val isEmpty: Boolean
+        get() = vertices.isEmpty() && edges.isEmpty() && hexes.isEmpty() && knights.isEmpty() && idleKnights.isEmpty()
+
+    /** Every crossing a tap can land on. */
+    val tappableVertices: Set<Int> get() = vertices + knights + idleKnights
+}
+
+/**
+ * A progress card that is waiting for a tap on the board: [plays] are every play
+ * of it the engine accepts, and the player's tap picks one. [firstHex] is the
+ * first of the two hexes an Inventor swaps, once tapped.
+ */
+data class ArmedCard(val kind: ProgressType, val plays: List<PlayProgress>, val firstHex: Int? = null)
+
+/** One progress card in the local player's hand, and the plays the engine allows for it. */
+data class ProgressInHand(val card: ProgressCard, val plays: List<PlayProgress>) {
+    val playable: Boolean get() = plays.isNotEmpty()
 }
 
 /** What a tap on the board amounts to. */
@@ -53,6 +111,12 @@ sealed interface TapOutcome {
 
     /** The robber's hex has more than one possible victim: ask which. */
     data class PickRobberVictim(val hex: HexCoord, val victims: List<Int>) : TapOutcome
+
+    /** One of the player's own knights was tapped: open its menu. */
+    data class PickKnight(val vertex: Int) : TapOutcome
+
+    /** An Inventor's first hex was tapped; the second completes the swap. */
+    data class PickFirstHex(val hex: Int) : TapOutcome
 }
 
 /**
@@ -78,6 +142,42 @@ data class DevCardInHand(val card: DevCard, val plays: List<CatanMove>) {
  */
 object CatanInteraction {
 
+    // --- Staged placements and drag-to-build ------------------------------------
+
+    /** A place on the board a dragged piece is over: one crossing or one edge. */
+    data class Spot(val vertex: Int? = null, val edge: Int? = null)
+
+    /**
+     * The spot a finger at [at] (board pixels) is nearest to, among [targets]. [reach] is
+     * generous (fingers cover what they point at), and edges are only offered when no
+     * crossing is lit, matching what a tap would do.
+     */
+    fun snap(layout: BoardLayout, targets: BoardTargets, at: Pt, reach: Float): Spot? = when {
+        targets.tappableVertices.isNotEmpty() ->
+            layout.nearestVertex(at, reach, targets.tappableVertices)?.let { Spot(vertex = it) }
+
+        targets.edges.isNotEmpty() -> layout.nearestEdge(at, reach, targets.edges)?.let { Spot(edge = it) }
+        else -> null
+    }
+
+    /** The move a build tap or drop would make, if it is a placement that waits for ✓. */
+    fun stageable(outcome: TapOutcome, building: BuildKind?): CatanMove? {
+        if (building == null || outcome !is TapOutcome.Submit) return null
+        return outcome.move.takeIf {
+            it is BuildRoad || it is BuildSettlement || it is BuildCity || it is BuildWall || it is HireKnight
+        }
+    }
+
+    /** Where a staged move sits on the board, for drawing its ghost. */
+    fun spotOf(move: CatanMove?): Spot = when (move) {
+        is BuildRoad -> Spot(edge = move.edge)
+        is BuildSettlement -> Spot(vertex = move.vertex)
+        is BuildCity -> Spot(vertex = move.vertex)
+        is BuildWall -> Spot(vertex = move.vertex)
+        is HireKnight -> Spot(vertex = move.vertex)
+        else -> Spot()
+    }
+
     // --- Board ---------------------------------------------------------------
 
     fun targets(
@@ -85,6 +185,10 @@ object CatanInteraction {
         legal: List<CatanMove>,
         building: BuildKind?,
         setupVertex: Int?,
+        movingKnight: Int? = null,
+        armed: ArmedCard? = null,
+        /** The local seat, so its sleeping knights can be tapped for their menu too. */
+        localSeat: Int? = null,
     ): BoardTargets {
         val setup = legal.filterIsInstance<SetupPlace>()
         if (setup.isNotEmpty()) {
@@ -100,9 +204,21 @@ object CatanInteraction {
             return BoardTargets(hexes = robber.mapNotNull { CatanBoard.hexIndex[it.hex] }.toSet())
         }
 
+        // Cities & Knights: answers to a queued chore are taps on the board.
+        val chore = choreVertices(legal)
+        if (chore.isNotEmpty()) return BoardTargets(vertices = chore)
+
         val roads = legal.filterIsInstance<BuildRoad>().map { it.edge }.toSet()
         if (state.phase == CatanPhase.FREE_ROADS) return BoardTargets(edges = roads)
 
+        if (armed != null) return armedTargets(armed)
+
+        if (movingKnight != null) {
+            return BoardTargets(
+                vertices = legal.filterIsInstance<MoveKnight>().filter { it.from == movingKnight }.map { it.to }.toSet(),
+            )
+        }
+
         return when (building) {
             BuildKind.ROAD -> BoardTargets(edges = roads)
             BuildKind.SETTLEMENT ->
@@ -111,15 +227,169 @@ object CatanInteraction {
             BuildKind.CITY ->
                 BoardTargets(vertices = legal.filterIsInstance<BuildCity>().map { it.vertex }.toSet())
 
-            null -> BoardTargets()
+            BuildKind.WALL ->
+                BoardTargets(vertices = legal.filterIsInstance<BuildWall>().map { it.vertex }.toSet())
+
+            BuildKind.KNIGHT ->
+                BoardTargets(vertices = legal.filterIsInstance<HireKnight>().map { it.vertex }.toSet())
+
+            null -> {
+                val ready = knightsWithActions(legal)
+                val mine = if (localSeat != null && legal.isNotEmpty()) {
+                    state.ck?.knights?.filter { it.owner == localSeat }?.map { it.vertex }?.toSet().orEmpty()
+                } else {
+                    emptySet()
+                }
+                BoardTargets(knights = ready, idleKnights = mine - ready)
+            }
         }
     }
 
+    /** The crossings a queued chore is asking the player to tap, from the legal list. */
+    private fun choreVertices(legal: List<CatanMove>): Set<Int> = buildSet {
+        legal.forEach { move ->
+            when (move) {
+                is PillageCity -> add(move.vertex)
+                is PlaceMetropolis -> add(move.vertex)
+                is RelocateKnight -> add(move.to)
+                is RemoveKnight -> add(move.vertex)
+                is PlaceKnight -> add(move.vertex)
+                else -> Unit
+            }
+        }
+        // A Smith's promotions are knights to tap, while the chore is open.
+        if (legal.any { it is EndSmith }) {
+            legal.filterIsInstance<PromoteKnight>().forEach { add(it.vertex) }
+        }
+    }
+
+    private fun choreMove(legal: List<CatanMove>, vertex: Int): CatanMove? = legal.firstOrNull { move ->
+        when (move) {
+            is PillageCity -> move.vertex == vertex
+            is PlaceMetropolis -> move.vertex == vertex
+            is RelocateKnight -> move.to == vertex
+            is RemoveKnight -> move.vertex == vertex
+            is PlaceKnight -> move.vertex == vertex
+            is PromoteKnight -> legal.any { it is EndSmith } && move.vertex == vertex
+            else -> false
+        }
+    }
+
+    // --- Cities & Knights: knights ---------------------------------------------
+
+    /** Crossings of the player's knights that have an action available. */
+    fun knightsWithActions(legal: List<CatanMove>): Set<Int> = buildSet {
+        legal.forEach { move ->
+            when (move) {
+                is ActivateKnight -> add(move.vertex)
+                is MoveKnight -> add(move.from)
+                is ChaseRobber -> add(move.vertex)
+                is PromoteKnight -> if (legal.none { it is EndSmith }) add(move.vertex)
+                else -> Unit
+            }
+        }
+    }
+
+    /** What the knight on [vertex] can do right now, in the order its menu lists them. */
+    fun knightActions(legal: List<CatanMove>, vertex: Int): List<CatanMove> =
+        legal.filter { move ->
+            when (move) {
+                is ActivateKnight -> move.vertex == vertex
+                is PromoteKnight -> move.vertex == vertex && legal.none { it is EndSmith }
+                is ChaseRobber -> move.vertex == vertex
+                else -> false
+            }
+        } + listOfNotNull(legal.firstOrNull { it is MoveKnight && it.from == vertex })
+
+    fun canEndSmith(legal: List<CatanMove>): Boolean = legal.any { it is EndSmith }
+
+    // --- Cities & Knights: progress cards --------------------------------------
+
+    /** [seat]'s progress cards, each with the plays the engine currently allows. */
+    fun progressHand(state: CatanState, seat: Int, legal: List<CatanMove>): List<ProgressInHand> =
+        state.ck?.progressHands?.getOrNull(seat).orEmpty().map { card ->
+            ProgressInHand(card, legal.filterIsInstance<PlayProgress>().filter { it.card == card.id })
+        }.sortedWith(compareBy({ it.card.kind.track.ordinal }, { it.card.kind.ordinal }, { it.card.id }))
+
+    /** The cards that are played by tapping the board, not by choosing in a dialog. */
+    val BOARD_CARDS: Set<ProgressType> = setOf(
+        ProgressType.ENGINEER, ProgressType.MEDICINE, ProgressType.MERCHANT,
+        ProgressType.DIPLOMAT, ProgressType.INTRIGUE, ProgressType.INVENTOR,
+    )
+
+    private fun armedTargets(armed: ArmedCard): BoardTargets = when (armed.kind) {
+        ProgressType.ENGINEER, ProgressType.MEDICINE, ProgressType.INTRIGUE ->
+            BoardTargets(vertices = armed.plays.mapNotNull { it.vertex }.toSet())
+
+        ProgressType.DIPLOMAT -> BoardTargets(edges = armed.plays.mapNotNull { it.edge }.toSet())
+
+        ProgressType.MERCHANT -> BoardTargets(hexes = armed.plays.mapNotNull { it.hexA }.toSet())
+
+        ProgressType.INVENTOR -> {
+            val first = armed.firstHex
+            val all = armed.plays.flatMap { listOfNotNull(it.hexA, it.hexB) }.toSet()
+            if (first == null) {
+                BoardTargets(hexes = all)
+            } else {
+                BoardTargets(
+                    hexes = armed.plays
+                        .filter { it.hexA == first || it.hexB == first }
+                        .flatMap { listOfNotNull(it.hexA, it.hexB) }
+                        .filter { it != first }
+                        .toSet(),
+                )
+            }
+        }
+
+        else -> BoardTargets()
+    }
+
+    /** The improvement tracks the player can buy a level of right now. */
+    fun improvable(legal: List<CatanMove>): Set<Track> =
+        legal.filterIsInstance<BuyImprovement>().map { it.track }.toSet()
+
+    // --- Cities & Knights: goods ----------------------------------------------
+
+    /** Bank trades on offer in Cities & Knights: what can be given, and for what. */
+    fun goodsBankTrades(legal: List<CatanMove>): Map<Good, List<Good>> =
+        legal.filterIsInstance<GoodsBankTrade>()
+            .groupBy({ it.give }, { it.get })
+            .mapValues { (_, gets) -> gets.sortedBy { it.ordinal } }
+            .toSortedMap(compareBy<Good> { it.ordinal })
+
+    fun goodsOfferAllowed(
+        state: CatanState,
+        seat: Int,
+        to: Int?,
+        give: List<Good>,
+        get: List<Good>,
+    ): Boolean = give.isNotEmpty() && get.isNotEmpty() &&
+        CatanRules.isLegalMove(state, seat, OfferGoods(to, give, get))
+
+    /** Whether [seat] may answer the goods offer on the table with [give] for [get]. */
+    fun goodsCounterAllowed(state: CatanState, seat: Int, give: List<Good>, get: List<Good>): Boolean =
+        give.isNotEmpty() && get.isNotEmpty() &&
+            CatanRules.isLegalMove(state, seat, CounterGoods(give, get))
+
+    /** The goods counter-offers the offerer may take right now, in the order they came in. */
+    fun goodsCounterChoices(state: CatanState, legal: List<CatanMove>): List<GoodsCounter> {
+        val takeable = legal.filterIsInstance<AcceptCounter>().map { it.seat }.toSet()
+        return state.ck?.goodsOffer?.counters.orEmpty().filter { it.by in takeable }
+    }
+
+    /** The chore at the front of the queue, if the table is waiting on one. */
+    fun chore(state: CatanState): Chore? =
+        if (state.phase == CatanPhase.CHORE) state.ck?.chores?.firstOrNull() else null
+
     fun onVertexTap(
         vertex: Int,
         legal: List<CatanMove>,
         building: BuildKind?,
         setupVertex: Int?,
+        movingKnight: Int? = null,
+        armed: ArmedCard? = null,
+        /** The local player's knights, which can be tapped for their menu even with nothing to do. */
+        ownKnights: Set<Int> = emptySet(),
     ): TapOutcome {
         val setup = legal.filterIsInstance<SetupPlace>()
         if (setup.isNotEmpty()) {
@@ -131,10 +401,27 @@ object CatanInteraction {
                 TapOutcome.Ignored
             }
         }
+        choreMove(legal, vertex)?.let { return TapOutcome.Submit(it) }
+
+        if (armed != null) {
+            val play = armed.plays.firstOrNull { it.vertex == vertex } ?: return TapOutcome.Ignored
+            return if (play in legal) TapOutcome.Submit(play) else TapOutcome.Ignored
+        }
+        if (movingKnight != null) {
+            val move = MoveKnight(movingKnight, vertex)
+            return if (move in legal) TapOutcome.Submit(move) else TapOutcome.Ignored
+        }
+
         val move: CatanMove = when (building) {
             BuildKind.SETTLEMENT -> BuildSettlement(vertex)
             BuildKind.CITY -> BuildCity(vertex)
-            else -> return TapOutcome.Ignored
+            BuildKind.WALL -> BuildWall(vertex)
+            BuildKind.KNIGHT -> HireKnight(vertex)
+            else -> return if (building == null && (vertex in knightsWithActions(legal) || vertex in ownKnights)) {
+                TapOutcome.PickKnight(vertex)
+            } else {
+                TapOutcome.Ignored
+            }
         }
         return if (move in legal) TapOutcome.Submit(move) else TapOutcome.Ignored
     }
@@ -144,12 +431,17 @@ object CatanInteraction {
         legal: List<CatanMove>,
         building: BuildKind?,
         setupVertex: Int?,
+        armed: ArmedCard? = null,
     ): TapOutcome {
         if (legal.any { it is SetupPlace }) {
             if (setupVertex == null) return TapOutcome.Ignored
             val move = SetupPlace(setupVertex, edge)
             return if (move in legal) TapOutcome.Submit(move) else TapOutcome.Ignored
         }
+        if (armed != null) {
+            val play = armed.plays.firstOrNull { it.edge == edge } ?: return TapOutcome.Ignored
+            return if (play in legal) TapOutcome.Submit(play) else TapOutcome.Ignored
+        }
         // Free roads need no build mode; a paid road does.
         val canBuild = building == BuildKind.ROAD || legal.any { it is EndFreeRoads }
         if (!canBuild) return TapOutcome.Ignored
@@ -157,7 +449,8 @@ object CatanInteraction {
         return if (move in legal) TapOutcome.Submit(move) else TapOutcome.Ignored
     }
 
-    fun onHexTap(hex: Int, legal: List<CatanMove>): TapOutcome {
+    fun onHexTap(hex: Int, legal: List<CatanMove>, armed: ArmedCard? = null): TapOutcome {
+        if (armed != null) return onArmedHexTap(hex, legal, armed)
         val coord = CatanBoard.HEXES.getOrNull(hex) ?: return TapOutcome.Ignored
         val moves = legal.filterIsInstance<MoveRobber>().filter { it.hex == coord }
         return when {
@@ -167,6 +460,22 @@ object CatanInteraction {
         }
     }
 
+    private fun onArmedHexTap(hex: Int, legal: List<CatanMove>, armed: ArmedCard): TapOutcome {
+        if (armed.kind == ProgressType.INVENTOR) {
+            val first = armed.firstHex ?: return if (hex in armedTargets(armed).hexes) {
+                TapOutcome.PickFirstHex(hex)
+            } else {
+                TapOutcome.Ignored
+            }
+            val play = armed.plays.firstOrNull {
+                (it.hexA == first && it.hexB == hex) || (it.hexA == hex && it.hexB == first)
+            } ?: return TapOutcome.Ignored
+            return if (play in legal) TapOutcome.Submit(play) else TapOutcome.Ignored
+        }
+        val play = armed.plays.firstOrNull { it.hexA == hex } ?: return TapOutcome.Ignored
+        return if (play in legal) TapOutcome.Submit(play) else TapOutcome.Ignored
+    }
+
     // --- Action bar ------------------------------------------------------------
 
     fun canRoll(legal: List<CatanMove>): Boolean = legal.any { it is RollDice }
@@ -200,6 +509,8 @@ object CatanInteraction {
         if (legal.any { it is BuildRoad }) add(BuildKind.ROAD)
         if (legal.any { it is BuildSettlement }) add(BuildKind.SETTLEMENT)
         if (legal.any { it is BuildCity }) add(BuildKind.CITY)
+        if (legal.any { it is BuildWall }) add(BuildKind.WALL)
+        if (legal.any { it is HireKnight }) add(BuildKind.KNIGHT)
     }
 
     fun tradeResponses(legal: List<CatanMove>): Pair<Boolean, Boolean> =
@@ -284,9 +595,20 @@ object CatanInteraction {
     fun offerAllowed(
         state: CatanState,
         seat: Int,
-        to: Int,
+        to: Int?,
         give: List<Resource>,
         get: List<Resource>,
     ): Boolean = give.isNotEmpty() && get.isNotEmpty() &&
         CatanRules.isLegalMove(state, seat, OfferTrade(to, give, get))
+
+    /** Whether [seat] may answer the offer on the table with [give] for [get]. */
+    fun counterAllowed(state: CatanState, seat: Int, give: List<Resource>, get: List<Resource>): Boolean =
+        give.isNotEmpty() && get.isNotEmpty() &&
+            CatanRules.isLegalMove(state, seat, CounterTrade(give, get))
+
+    /** The counter-offers the offerer may take right now, in the order they came in. */
+    fun counterChoices(state: CatanState, legal: List<CatanMove>): List<TradeCounter> {
+        val takeable = legal.filterIsInstance<AcceptCounter>().map { it.seat }.toSet()
+        return state.pendingTrade?.counters.orEmpty().filter { it.by in takeable }
+    }
 }

app/src/main/java/org/prolibertate/games/ui/game/catan/CatanPanels.kt

@@ -40,10 +40,15 @@ import androidx.compose.ui.text.style.TextAlign
 import androidx.compose.ui.text.style.TextOverflow
 import androidx.compose.ui.unit.dp
 import androidx.compose.ui.unit.sp
+import org.prolibertate.games.game.catan.BuildingType
+import org.prolibertate.games.game.catan.CatanCk
 import org.prolibertate.games.game.catan.CatanPhase
 import org.prolibertate.games.game.catan.CatanRules
 import org.prolibertate.games.game.catan.CatanState
+import org.prolibertate.games.game.catan.EventFace
+import org.prolibertate.games.game.catan.Good
 import org.prolibertate.games.game.catan.Resource
+import org.prolibertate.games.game.catan.Track
 
 /*
  * Stateless building blocks for the Katan screen.
@@ -102,7 +107,52 @@ fun ResourceTile(
     }
 }
 
-/** The local player's cards: one tile per resource, in a row that wraps. */
+/**
+ * One card type — a resource or a commodity — as a coloured tile with its count.
+ * Cities & Knights hands, discards and trades use this so commodities look the
+ * same everywhere.
+ */
+@Composable
+fun GoodTile(
+    good: Good,
+    count: Int,
+    modifier: Modifier = Modifier,
+    selected: Boolean = false,
+    enabled: Boolean = true,
+    style: CatanStyle = LocalCatanStyle.current,
+    onClick: (() -> Unit)? = null,
+) {
+    val resource = good.resource
+    if (resource != null) {
+        ResourceTile(resource, count, modifier, selected, enabled, style, onClick)
+        return
+    }
+    val commodity = good.commodity!!
+    val shape = RoundedCornerShape(10.dp)
+    val ink = style.commodityInk.getValue(commodity)
+    Column(
+        modifier = modifier
+            .defaultMinSize(minWidth = 56.dp)
+            .clip(shape)
+            .background(style.commodity.getValue(commodity).copy(alpha = if (enabled) 1f else 0.4f))
+            .border(
+                width = if (selected) 3.dp else 1.dp,
+                color = if (selected) Color.White else Color(0x33000000),
+                shape = shape,
+            )
+            .then(if (onClick != null && enabled) Modifier.clickable { onClick() } else Modifier)
+            .padding(horizontal = 6.dp, vertical = 6.dp),
+        horizontalAlignment = Alignment.CenterHorizontally,
+    ) {
+        Text(text = count.toString(), color = ink, fontWeight = FontWeight.Bold, fontSize = 20.sp)
+        Text(text = CatanText.good(good), color = ink, fontSize = 11.sp, maxLines = 1)
+    }
+}
+
+/**
+ * The local player's cards: one tile per resource, and in Cities & Knights one
+ * per commodity as well, in a row that wraps.
+ */
 @OptIn(ExperimentalLayoutApi::class)
 @Composable
 fun CatanHand(
@@ -115,8 +165,13 @@ fun CatanHand(
         horizontalArrangement = Arrangement.spacedBy(6.dp),
         verticalArrangement = Arrangement.spacedBy(6.dp),
     ) {
-        Resource.entries.forEach { resource ->
-            ResourceTile(resource, state.resources[seat][resource] ?: 0)
+        if (state.isCk) {
+            val held = CatanCk.goodsOf(state, seat)
+            Good.entries.forEach { good -> GoodTile(good, held[good] ?: 0) }
+        } else {
+            Resource.entries.forEach { resource ->
+                ResourceTile(resource, state.resources[seat][resource] ?: 0)
+            }
         }
     }
 }
@@ -175,6 +230,41 @@ fun CatanPlayerCard(
             CardLine(seats.label(seat), MaterialTheme.typography.labelLarge, FontWeight.Bold)
         }
         CardLine("$points VP", MaterialTheme.typography.titleMedium, FontWeight.Bold)
+        val ck = state.ck
+        if (ck != null) {
+            val cards = CatanCk.goodsCount(state, seat)
+            val strength = CatanCk.strength(state, seat)
+            if (compact) {
+                CardLine("$cards cards · ⚔$strength", MaterialTheme.typography.bodySmall)
+            } else {
+                CardLine("$cards cards · ${ck.progressCounts[seat]} progress", MaterialTheme.typography.bodySmall)
+                CardLine(
+                    "⚔ ${CatanCk.knightsOf(state, seat).size} · str $strength · " +
+                        "Road ${CatanRules.longestRoadFor(state, seat)}",
+                    MaterialTheme.typography.bodySmall,
+                )
+            }
+            // Trade, politics, science: the three improvement levels.
+            CardLine(
+                Track.entries.joinToString(" ") { "${it.name.first()}${CatanCk.improvement(state, seat, it)}" },
+                MaterialTheme.typography.bodySmall,
+                color = Color.Unspecified,
+            )
+            val ckAwards = buildList {
+                if (state.longestRoadOwner == seat) add(if (compact) "Road" else "Longest road")
+                ck.metropolises.forEach { (track, at) ->
+                    if (at.seat == seat) add(if (compact) track.name.first().toString() else "${CatanText.track(track)} metropolis")
+                }
+                if (ck.merchant?.seat == seat) add("Merchant")
+            }
+            CardLine(
+                text = ckAwards.joinToString(" · ").ifEmpty { BLANK },
+                style = MaterialTheme.typography.labelSmall,
+                weight = FontWeight.Bold,
+                color = MaterialTheme.colorScheme.primary,
+            )
+            return@Column
+        }
         if (compact) {
             CardLine("${state.resourceCount(seat)} cards", MaterialTheme.typography.bodySmall)
         } else {
@@ -226,21 +316,36 @@ private fun CardLine(
 // Dice
 // ---------------------------------------------------------------------------
 
-/** The two dice as last rolled, with their total. Blank until the first roll. */
+/**
+ * The two dice as last rolled, with their total. Blank until the first roll. In
+ * Cities & Knights the dice are yellow and red (the red one decides progress
+ * cards) and a third, the event die, shows a ship or a coloured city gate.
+ */
 @Composable
-fun CatanDice(dice: List<Int>, modifier: Modifier = Modifier) {
+fun CatanDice(
+    dice: List<Int>,
+    modifier: Modifier = Modifier,
+    ck: Boolean = false,
+    event: EventFace? = null,
+    style: CatanStyle = LocalCatanStyle.current,
+) {
     Row(
         modifier = modifier,
         verticalAlignment = Alignment.CenterVertically,
         horizontalArrangement = Arrangement.spacedBy(6.dp),
     ) {
         val shown = if (dice.size == 2) dice else listOf(null, null)
-        shown.forEach { value ->
+        shown.forEachIndexed { index, value ->
+            val face = when {
+                !ck -> Color.White
+                index == 0 -> Color(0xFFFFF176)
+                else -> Color(0xFFEF9A9A)
+            }
             Box(
                 modifier = Modifier
                     .size(36.dp)
                     .clip(RoundedCornerShape(8.dp))
-                    .background(Color.White)
+                    .background(face)
                     .border(1.dp, Color(0x55000000), RoundedCornerShape(8.dp)),
                 contentAlignment = Alignment.Center,
             ) {
@@ -253,6 +358,31 @@ fun CatanDice(dice: List<Int>, modifier: Modifier = Modifier) {
                 )
             }
         }
+        if (ck) {
+            val gate = when (event) {
+                EventFace.TRADE -> style.track.getValue(Track.TRADE)
+                EventFace.POLITICS -> style.track.getValue(Track.POLITICS)
+                EventFace.SCIENCE -> style.track.getValue(Track.SCIENCE)
+                EventFace.SHIP -> style.barbarian
+                null -> Color(0x33000000)
+            }
+            Box(
+                modifier = Modifier
+                    .size(width = 52.dp, height = 36.dp)
+                    .clip(RoundedCornerShape(8.dp))
+                    .background(gate)
+                    .border(1.dp, Color(0x55000000), RoundedCornerShape(8.dp)),
+                contentAlignment = Alignment.Center,
+            ) {
+                Text(
+                    text = if (event == EventFace.SHIP) "⛵ Ship" else CatanText.event(event),
+                    color = if (event == EventFace.TRADE) Color(0xFF1C1B1F) else Color.White,
+                    fontWeight = FontWeight.Bold,
+                    fontSize = 11.sp,
+                    maxLines = 1,
+                )
+            }
+        }
         // Always drawn ("= –" before the first roll) so the row never changes width.
         Text(
             text = if (dice.size == 2) "= ${dice.sum()}" else "= –",
@@ -262,6 +392,48 @@ fun CatanDice(dice: List<Int>, modifier: Modifier = Modifier) {
     }
 }
 
+/**
+ * Cities & Knights: how close the barbarians are, and how the cities on the
+ * island compare with the knights standing ready. **Fixed height**, like every
+ * other strip around the board.
+ */
+@Composable
+fun CatanBarbarians(state: CatanState, modifier: Modifier = Modifier, style: CatanStyle = LocalCatanStyle.current) {
+    val ck = state.ck ?: return
+    val cities = state.buildings.count { it?.type == BuildingType.CITY }
+    val defence = (0 until state.playerCount).sumOf { CatanCk.strength(state, it) }
+    Row(
+        modifier = modifier.fillMaxWidth().height(24.dp),
+        verticalAlignment = Alignment.CenterVertically,
+        horizontalArrangement = Arrangement.spacedBy(6.dp),
+    ) {
+        Text("⛵", fontSize = 14.sp)
+        Row(horizontalArrangement = Arrangement.spacedBy(2.dp), modifier = Modifier.weight(1f)) {
+            // The ship starts seven steps out and lands when the last box fills.
+            val sailed = BARBARIAN_STEPS_DISPLAY - ck.barbarians
+            for (i in 0 until BARBARIAN_STEPS_DISPLAY) {
+                Box(
+                    modifier = Modifier
+                        .weight(1f)
+                        .height(10.dp)
+                        .clip(RoundedCornerShape(3.dp))
+                        .background(if (i < sailed) style.barbarian else Color(0x33000000)),
+                )
+            }
+        }
+        val verdict = if (defence >= cities) "holds" else "falls"
+        Text(
+            text = "${CatanText.barbarianSteps(ck.barbarians)} · knights $defence v. $cities cities ($verdict)",
+            style = MaterialTheme.typography.labelSmall,
+            maxLines = 1,
+            overflow = TextOverflow.Ellipsis,
+        )
+    }
+}
+
+/** Steps shown on the barbarian strip: the engine's seven. */
+private const val BARBARIAN_STEPS_DISPLAY = org.prolibertate.games.game.catan.BARBARIAN_STEPS
+
 // ---------------------------------------------------------------------------
 // Actions
 // ---------------------------------------------------------------------------
@@ -278,6 +450,14 @@ data class CatanActions(
     val canEndFreeRoads: Boolean = false,
     /** A setup settlement is chosen and a different one may still be picked. */
     val canRepickSetup: Boolean = false,
+    /** Which kinds the Build menu lists: three in the base game, five in Cities & Knights. */
+    val buildKinds: List<BuildKind> = BuildKind.BASE,
+    /** Cities & Knights: the table plays the expansion, so the bar shows its buttons instead. */
+    val ck: Boolean = false,
+    val canImprove: Boolean = false,
+    val canPlayProgress: Boolean = false,
+    val progressCount: Int = 0,
+    val canEndSmith: Boolean = false,
 )
 
 /**
@@ -305,6 +485,9 @@ fun CatanActionBar(
     modifier: Modifier = Modifier,
     /** Small screens: fold Road / Settlement / City into one "Build" button with a menu. */
     compact: Boolean = false,
+    onImprove: () -> Unit = {},
+    onProgress: () -> Unit = {},
+    onEndSmith: () -> Unit = {},
 ) {
     Column(modifier = modifier.fillMaxWidth(), verticalArrangement = Arrangement.spacedBy(8.dp)) {
         Row(
@@ -315,6 +498,7 @@ fun CatanActionBar(
             if (actions.canRoll) Button(onClick = onRoll) { Text(CatanText.ROLL) }
             if (actions.canRepickSetup) OutlinedButton(onClick = onRepickSetup) { Text(CatanText.CANCEL) }
             if (actions.canEndFreeRoads) Button(onClick = onEndFreeRoads) { Text(CatanText.STOP_ROADS) }
+            if (actions.canEndSmith) Button(onClick = onEndSmith) { Text(CatanText.STOP_SMITH) }
             if (actions.canEndTurn) Button(onClick = onEndTurn) { Text(CatanText.END_TURN) }
         }
 
@@ -323,18 +507,27 @@ fun CatanActionBar(
             horizontalArrangement = Arrangement.spacedBy(8.dp),
             verticalArrangement = Arrangement.spacedBy(8.dp),
         ) {
-            if (compact) {
+            if (compact || actions.ck) {
                 BuildMenuButton(actions, onBuild)
             } else {
                 BuildButton(BuildKind.ROAD, CatanText.ROAD, CatanText.ROAD_COST, actions, onBuild)
                 BuildButton(BuildKind.SETTLEMENT, CatanText.SETTLEMENT, CatanText.SETTLEMENT_COST, actions, onBuild)
                 BuildButton(BuildKind.CITY, CatanText.CITY, CatanText.CITY_COST, actions, onBuild)
             }
-            OutlinedButton(onClick = onBuyCard, enabled = actions.canBuyCard) {
-                LabelWithCost(CatanText.BUY_CARD, CatanText.DEV_COST)
-            }
-            OutlinedButton(onClick = onPlayCard, enabled = actions.canPlayCard) {
-                LabelWithCost(CatanText.PLAY_CARD, CatanText.NO_COST)
+            if (actions.ck) {
+                OutlinedButton(onClick = onImprove, enabled = actions.canImprove) {
+                    LabelWithCost(CatanText.IMPROVE, CatanText.NO_COST)
+                }
+                OutlinedButton(onClick = onProgress, enabled = actions.canPlayProgress) {
+                    LabelWithCost(CatanText.CARDS_BUTTON, "${actions.progressCount} held")
+                }
+            } else {
+                OutlinedButton(onClick = onBuyCard, enabled = actions.canBuyCard) {
+                    LabelWithCost(CatanText.BUY_CARD, CatanText.DEV_COST)
+                }
+                OutlinedButton(onClick = onPlayCard, enabled = actions.canPlayCard) {
+                    LabelWithCost(CatanText.PLAY_CARD, CatanText.NO_COST)
+                }
             }
             OutlinedButton(onClick = onTrade, enabled = actions.canTrade) {
                 LabelWithCost(CatanText.TRADE, CatanText.NO_COST)
@@ -384,7 +577,7 @@ private fun BuildMenuButton(actions: CatanActions, onBuild: (BuildKind?) -> Unit
             OutlinedButton(onClick = { open = true }, enabled = anyEnabled) { label() }
         }
         DropdownMenu(expanded = open, onDismissRequest = { open = false }) {
-            for (kind in BuildKind.entries) {
+            for (kind in actions.buildKinds) {
                 DropdownMenuItem(
                     text = { LabelWithCost(buildLabel(kind), buildCost(kind)) },
                     enabled = kind in actions.canBuild,
@@ -402,12 +595,16 @@ private fun buildLabel(kind: BuildKind): String = when (kind) {
     BuildKind.ROAD -> CatanText.ROAD
     BuildKind.SETTLEMENT -> CatanText.SETTLEMENT
     BuildKind.CITY -> CatanText.CITY
+    BuildKind.WALL -> CatanText.WALL
+    BuildKind.KNIGHT -> CatanText.KNIGHT
 }
 
 private fun buildCost(kind: BuildKind): String = when (kind) {
     BuildKind.ROAD -> CatanText.ROAD_COST
     BuildKind.SETTLEMENT -> CatanText.SETTLEMENT_COST
     BuildKind.CITY -> CatanText.CITY_COST
+    BuildKind.WALL -> CatanText.WALL_COST
+    BuildKind.KNIGHT -> CatanText.KNIGHT_COST
 }
 
 @Composable

app/src/main/java/org/prolibertate/games/ui/game/catan/CatanScreen.kt

@@ -9,6 +9,15 @@ import androidx.compose.foundation.layout.Row
 import androidx.compose.foundation.layout.fillMaxSize
 import androidx.compose.foundation.layout.fillMaxWidth
 import androidx.compose.foundation.layout.height
+import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.horizontalScroll
+import androidx.compose.foundation.background
+import androidx.compose.material3.Surface
+import androidx.compose.ui.geometry.Offset
+import androidx.compose.ui.layout.LayoutCoordinates
+import androidx.compose.ui.layout.onGloballyPositioned
+import androidx.compose.ui.unit.IntSize
+import org.prolibertate.games.game.catan.BuildRoad
 import androidx.compose.foundation.rememberScrollState
 import androidx.compose.foundation.verticalScroll
 import androidx.compose.material3.MaterialTheme
@@ -22,23 +31,37 @@ import androidx.compose.runtime.getValue
 import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.remember
 import androidx.compose.runtime.setValue
+import androidx.compose.ui.platform.LocalConfiguration
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.graphics.Color
 import androidx.compose.ui.text.style.TextOverflow
 import androidx.compose.ui.unit.dp
 import org.prolibertate.games.game.catan.AcceptTrade
+import org.prolibertate.games.game.catan.AqueductChore
 import org.prolibertate.games.game.catan.BuyDevCard
+import org.prolibertate.games.game.catan.CatanCk
 import org.prolibertate.games.game.catan.CatanMove
 import org.prolibertate.games.game.catan.CatanPhase
 import org.prolibertate.games.game.catan.CatanRules
 import org.prolibertate.games.game.catan.CatanState
 import org.prolibertate.games.game.catan.DeclineTrade
+import org.prolibertate.games.game.catan.DiscardChore
+import org.prolibertate.games.game.catan.DiscardGoods
+import org.prolibertate.games.game.catan.DropProgress
+import org.prolibertate.games.game.catan.DropProgressChore
+import org.prolibertate.games.game.catan.DismissCounters
 import org.prolibertate.games.game.catan.EndFreeRoads
+import org.prolibertate.games.game.catan.EndSmith
 import org.prolibertate.games.game.catan.EndTurn
+import org.prolibertate.games.game.catan.GiveChore
+import org.prolibertate.games.game.catan.GiveGoods
+import org.prolibertate.games.game.catan.MoveKnight
 import org.prolibertate.games.game.catan.MoveRobber
+import org.prolibertate.games.game.catan.PickDeckChore
 import org.prolibertate.games.game.catan.RollDice
 import org.prolibertate.games.game.catan.SetupPlace
+import org.prolibertate.games.game.catan.SpyChore
 import org.prolibertate.games.net.MatchController
 import org.prolibertate.games.ui.ScreenScaffold
 
@@ -84,6 +107,25 @@ fun CatanScreen(
     var showTrade by remember { mutableStateOf(false) }
     var confirmingEnd by remember { mutableStateOf(false) }
     var resultDismissed by remember { mutableStateOf(false) }
+    // Cities & Knights: the knight whose menu is open, the one about to move,
+    // a progress card waiting for a tap on the board, and the two list dialogs.
+    var knightMenu by remember { mutableStateOf<Int?>(null) }
+    var movingKnight by remember { mutableStateOf<Int?>(null) }
+    var armed by remember { mutableStateOf<ArmedCard?>(null) }
+    var showImprove by remember { mutableStateOf(false) }
+    var showProgress by remember { mutableStateOf(false) }
+    // The landscape HUD: a placement waiting for its ✓, the piece being dragged from the
+    // build column (and where the finger is, in window pixels), the log popup, and the board.
+    var staged by remember { mutableStateOf<CatanMove?>(null) }
+    var dragKind by remember { mutableStateOf<BuildKind?>(null) }
+    var dragAt by remember { mutableStateOf<Offset?>(null) }
+    var showLog by remember { mutableStateOf(false) }
+    var boardCoords by remember { mutableStateOf<LayoutCoordinates?>(null) }
+
+    val config = LocalConfiguration.current
+    // Landscape gets the heads-up display; portrait keeps the stacked layout.
+    val wide = config.screenWidthDp > config.screenHeightDp * 1.1f
+    val staging = wide
 
     val dark = isSystemInDarkTheme()
     val style = remember(dark) { catanStyle(dark) }
@@ -94,13 +136,22 @@ fun CatanScreen(
     // settlement that is no longer pending).
     LaunchedEffect(legal) {
         if (building != null && building !in CatanInteraction.canBuild(legal)) building = null
+        if (staged != null && staged !in legal) staged = null
         if (setupVertex != null && legal.none { it is SetupPlace && it.vertex == setupVertex }) {
             setupVertex = null
         }
+        if (movingKnight != null && legal.none { it is MoveKnight && it.from == movingKnight }) movingKnight = null
+        armed?.let { card -> if (card.plays.none { it in legal }) armed = null }
         if (legal.isEmpty()) {
             showCards = false
             showTrade = false
             victimChoice = null
+            showImprove = false
+            showProgress = false
+            knightMenu = null
+            movingKnight = null
+            armed = null
+            staged = null
         }
     }
 
@@ -111,6 +162,14 @@ fun CatanScreen(
         victimChoice = null
         showCards = false
         showTrade = false
+        showImprove = false
+        showProgress = false
+        knightMenu = null
+        movingKnight = null
+        armed = null
+        staged = null
+        dragKind = null
+        dragAt = null
     }
 
     val endGameAction: @Composable () -> Unit = {
@@ -127,10 +186,18 @@ fun CatanScreen(
         return
     }
 
-    val targets = CatanInteraction.targets(current, legal, building, setupVertex)
+    val targets = CatanInteraction.targets(current, legal, building, setupVertex, movingKnight, armed, localSeat)
+    val ownKnights = current.ck?.knights?.filter { it.owner == localSeat }?.map { it.vertex }?.toSet().orEmpty()
     val devHand = CatanInteraction.devHand(current, localSeat, legal)
+    val progressHand = CatanInteraction.progressHand(current, localSeat, legal)
     val playing = current.phase == CatanPhase.PLAYING && legal.isNotEmpty()
     val actions = CatanActions(
+        buildKinds = if (current.isCk) BuildKind.entries else BuildKind.BASE,
+        ck = current.isCk,
+        canImprove = CatanInteraction.improvable(legal).isNotEmpty(),
+        canPlayProgress = progressHand.any { it.playable },
+        progressCount = progressHand.size,
+        canEndSmith = CatanInteraction.canEndSmith(legal),
         canRoll = CatanInteraction.canRoll(legal),
         canBuild = CatanInteraction.canBuild(legal),
         building = building,
@@ -142,14 +209,27 @@ fun CatanScreen(
         canRepickSetup = setupVertex != null,
     )
     val rolledHexes = CatanInteraction.rolledHexes(current)
-    val prompt = CatanText.prompt(current, seats, setupVertexChosen = setupVertex != null, building = building)
+    val prompt = CatanText.prompt(
+        current,
+        seats,
+        setupVertexChosen = setupVertex != null,
+        building = building,
+        movingKnight = movingKnight != null,
+        armed = armed?.kind,
+    )
 
     val handle: (TapOutcome) -> Unit = { outcome ->
-        when (outcome) {
+        val wait = if (staging) CatanInteraction.stageable(outcome, building) else null
+        when {
+            wait != null -> staged = wait
+            else -> when (outcome) {
             TapOutcome.Ignored -> Unit
             is TapOutcome.Submit -> submit(outcome.move)
             is TapOutcome.PickSetupVertex -> setupVertex = outcome.vertex
             is TapOutcome.PickRobberVictim -> victimChoice = outcome
+            is TapOutcome.PickKnight -> knightMenu = outcome.vertex
+            is TapOutcome.PickFirstHex -> armed = armed?.copy(firstHex = outcome.hex)
+            }
         }
     }
 
@@ -161,21 +241,36 @@ fun CatanScreen(
     CompositionLocalProvider(LocalCatanStyle provides style) {
         ScreenScaffold(title = CatanText.TITLE, onBack = onExit, actions = endGameAction) { modifier ->
             BoxWithConstraints(modifier = modifier) {
-                val wide = maxWidth > maxHeight * 1.1f
                 // Phones (either way up) get the one-button build menu.
                 val compactBuild = !wide || maxWidth < 600.dp
 
+                val hoverSpot = if (dragKind != null) dragSpot(boardCoords, dragAt, targets) else null
+                val stagedSpot = CatanInteraction.spotOf(staged)
+                val ghostVertex = hoverSpot?.vertex ?: stagedSpot.vertex
+                val ghostEdge = hoverSpot?.edge ?: stagedSpot.edge
+
                 val board: @Composable (Modifier) -> Unit = { boardModifier ->
                     CatanBoardView(
                         state = current,
                         targets = targets,
                         selectedVertex = setupVertex,
-                        onVertexTap = { handle(CatanInteraction.onVertexTap(it, legal, building, setupVertex)) },
-                        onEdgeTap = { handle(CatanInteraction.onEdgeTap(it, legal, building, setupVertex)) },
-                        onHexTap = { handle(CatanInteraction.onHexTap(it, legal)) },
+                        onVertexTap = {
+                            handle(
+                                CatanInteraction.onVertexTap(
+                                    it, legal, building, setupVertex, movingKnight, armed,
+                                    ownKnights = if (legal.isNotEmpty()) ownKnights else emptySet(),
+                                ),
+                            )
+                        },
+                        onEdgeTap = { handle(CatanInteraction.onEdgeTap(it, legal, building, setupVertex, armed)) },
+                        onHexTap = { handle(CatanInteraction.onHexTap(it, legal, armed)) },
                         modifier = boardModifier,
                         style = style,
                         rolledHexes = rolledHexes,
+                        selectedKnight = movingKnight ?: knightMenu,
+                        stagedVertex = ghostVertex,
+                        stagedEdge = ghostEdge,
+                        stagedSeat = localSeat,
                     )
                 }
                 val players: @Composable (Boolean) -> Unit = { grid ->
@@ -200,28 +295,73 @@ fun CatanScreen(
                             },
                             onRepickSetup = { setupVertex = null },
                             compact = compactBuild,
+                            onImprove = { showImprove = true },
+                            onProgress = { showProgress = true },
+                            onEndSmith = { legal.firstOrNull { m -> m is EndSmith }?.let(submit) },
                         )
                     }
                 }
 
                 if (wide) {
-                    Row(Modifier.fillMaxSize(), horizontalArrangement = Arrangement.spacedBy(12.dp)) {
-                        Box(Modifier.weight(1.5f).fillMaxSize(), contentAlignment = Alignment.Center) {
-                            board(Modifier)
-                        }
-                        Column(
-                            modifier = Modifier.weight(1f).fillMaxSize().verticalScroll(rememberScrollState()),
-                            verticalArrangement = Arrangement.spacedBy(8.dp),
-                        ) {
-                            players(true)
-                            promptRow()
-                            handAndActions()
-                            CatanLog(current, Modifier.fillMaxWidth().height(120.dp))
-                        }
-                    }
+                    CatanHud(
+                        state = current,
+                        seats = seats,
+                        style = style,
+                        actions = actions,
+                        prompt = prompt,
+                        notice = notice,
+                        legal = legal,
+                        localSeat = localSeat,
+                        targets = targets,
+                        pointsOf = pointsOf,
+                        staged = staged,
+                        dragKind = dragKind,
+                        dragAt = dragAt,
+                        showLog = showLog,
+                        boardCoords = boardCoords,
+                        building = building,
+                        onBoardCoords = { boardCoords = it },
+                        onToggleLog = { showLog = !showLog },
+                        onArm = { kind -> building = if (building == kind) null else kind; staged = null },
+                        onDragStart = { kind, at ->
+                            building = kind
+                            staged = null
+                            dragKind = kind
+                            dragAt = at
+                        },
+                        onDrag = { dragAt = it },
+                        onDragEnd = {
+                            val spot = dragSpot(boardCoords, dragAt, targets)
+                            dragKind = null
+                            dragAt = null
+                            val outcome = when {
+                                spot?.vertex != null -> CatanInteraction.onVertexTap(
+                                    spot.vertex, legal, building, setupVertex,
+                                    ownKnights = if (legal.isNotEmpty()) ownKnights else emptySet(),
+                                )
+                                spot?.edge != null -> CatanInteraction.onEdgeTap(spot.edge, legal, building, setupVertex, armed)
+                                else -> TapOutcome.Ignored
+                            }
+                            handle(outcome)
+                        },
+                        onConfirm = { staged?.let(submit) },
+                        onCancelStaged = { staged = null; building = null },
+                        onRoll = { submit(RollDice()) },
+                        onEndTurn = { legal.firstOrNull { m -> m is EndTurn }?.let(submit) },
+                        onEndFreeRoads = { legal.firstOrNull { m -> m is EndFreeRoads }?.let(submit) },
+                        onEndSmith = { legal.firstOrNull { m -> m is EndSmith }?.let(submit) },
+                        onRepickSetup = { setupVertex = null },
+                        onBuyCard = { legal.firstOrNull { m -> m is BuyDevCard }?.let(submit) },
+                        onPlayCard = { showCards = true },
+                        onTrade = { showTrade = true },
+                        onImprove = { showImprove = true },
+                        onProgress = { showProgress = true },
+                        board = { m -> board(m) },
+                    )
                 } else {
                     Column(Modifier.fillMaxSize(), verticalArrangement = Arrangement.spacedBy(8.dp)) {
                         players(false)
+                        if (current.isCk) CatanBarbarians(current, style = style)
                         promptRow()
                         Box(Modifier.weight(1f).fillMaxWidth(), contentAlignment = Alignment.Center) {
                             board(Modifier)
@@ -229,6 +369,39 @@ fun CatanScreen(
                         handAndActions()
                     }
                 }
+
+                // The trade board slides up over the bottom of the island (base game; Cities &
+                // Knights trades goods and still uses its dialogs).
+                val offerToMe = current.pendingTrade?.takeIf {
+                    current.phase == CatanPhase.TRADE_PENDING && it.asking == localSeat && !current.isCk
+                }
+                val boardsAllowed = abandoned == null && !confirmingEnd && current.phase != CatanPhase.GAME_OVER
+                if (boardsAllowed && offerToMe != null) {
+                    CatanTradeReplyBoard(
+                        state = current,
+                        seat = localSeat,
+                        offer = offerToMe,
+                        seats = seats,
+                        canAccept = CatanInteraction.tradeResponses(legal).first,
+                        onAccept = { submit(AcceptTrade) },
+                        onDecline = { submit(DeclineTrade) },
+                        onCounter = submit,
+                        modifier = Modifier.align(Alignment.BottomCenter),
+                        style = style,
+                    )
+                } else if (boardsAllowed && showTrade && !current.isCk) {
+                    CatanTradeBoard(
+                        state = current,
+                        seat = localSeat,
+                        seats = seats,
+                        legal = legal,
+                        onBank = submit,
+                        onOffer = submit,
+                        onClose = { showTrade = false },
+                        modifier = Modifier.align(Alignment.BottomCenter),
+                        style = style,
+                    )
+                }
             }
 
             CatanDialogHost(
@@ -243,6 +416,21 @@ fun CatanScreen(
                 showCards = showCards,
                 showTrade = showTrade,
                 devHand = devHand,
+                knightMenu = knightMenu,
+                showImprove = showImprove,
+                showProgress = showProgress,
+                progressHand = progressHand,
+                onMoveKnight = { from ->
+                    knightMenu = null
+                    movingKnight = from
+                },
+                onArmCard = { card ->
+                    showProgress = false
+                    armed = card
+                },
+                onCancelKnight = { knightMenu = null },
+                onCancelImprove = { showImprove = false },
+                onCancelProgress = { showProgress = false },
                 onExit = onExit,
                 onSubmit = submit,
                 onStay = controller::dismissAbandoned,
@@ -315,7 +503,7 @@ private fun PromptRow(prompt: String, notice: String?, state: CatanState) {
             overflow = TextOverflow.Ellipsis,
             modifier = Modifier.weight(1f),
         )
-        CatanDice(state.lastDice)
+        CatanDice(state.lastDice, ck = state.isCk, event = state.ck?.eventDie)
     }
 }
 
@@ -337,6 +525,15 @@ private fun CatanDialogHost(
     showCards: Boolean,
     showTrade: Boolean,
     devHand: List<DevCardInHand>,
+    knightMenu: Int?,
+    showImprove: Boolean,
+    showProgress: Boolean,
+    progressHand: List<ProgressInHand>,
+    onMoveKnight: (Int) -> Unit,
+    onArmCard: (ArmedCard) -> Unit,
+    onCancelKnight: () -> Unit,
+    onCancelImprove: () -> Unit,
+    onCancelProgress: () -> Unit,
     onExit: () -> Unit,
     onSubmit: (CatanMove) -> Unit,
     onStay: () -> Unit,
@@ -346,7 +543,7 @@ private fun CatanDialogHost(
     onCancelCards: () -> Unit,
     onCancelTrade: () -> Unit,
 ) {
-    val offer = state.pendingTrade
+    val goodsOffer = state.ck?.goodsOffer
     when {
         abandoned != null -> CatanAbandonedDialog(abandoned, onExit, onStay)
 
@@ -363,13 +560,35 @@ private fun CatanDialogHost(
                 onSubmit = onSubmit,
             )
 
-        state.phase == CatanPhase.TRADE_PENDING && offer != null && offer.to == localSeat ->
-            CatanTradeResponseDialog(
-                offer = offer,
+        state.phase == CatanPhase.CHORE && CatanRules.currentSeat(state) == localSeat ->
+            ChoreDialog(state, localSeat, legal, onSubmit)
+
+        state.phase == CatanPhase.TRADE_PENDING && goodsOffer != null && goodsOffer.asking == localSeat ->
+            CatanGoodsTradeResponseDialog(
+                state = state,
+                seat = localSeat,
+                offer = goodsOffer,
                 seats = seats,
                 canAccept = CatanInteraction.tradeResponses(legal).first,
                 onAccept = { onSubmit(AcceptTrade) },
                 onDecline = { onSubmit(DeclineTrade) },
+                onCounter = onSubmit,
+            )
+
+        state.phase == CatanPhase.TRADE_COUNTERS && goodsOffer != null && state.turn == localSeat && legal.isNotEmpty() ->
+            CatanGoodsCounterChoiceDialog(
+                counters = CatanInteraction.goodsCounterChoices(state, legal),
+                seats = seats,
+                onTake = onSubmit,
+                onNoDeal = { onSubmit(DismissCounters) },
+            )
+
+        state.phase == CatanPhase.TRADE_COUNTERS && state.turn == localSeat && legal.isNotEmpty() ->
+            CatanCounterChoiceDialog(
+                counters = CatanInteraction.counterChoices(state, legal),
+                seats = seats,
+                onTake = onSubmit,
+                onNoDeal = { onSubmit(DismissCounters) },
             )
 
         victimChoice != null ->
@@ -380,10 +599,38 @@ private fun CatanDialogHost(
                 onCancel = onCancelVictim,
             )
 
+        knightMenu != null ->
+            CatanKnightDialog(
+                state = state,
+                vertex = knightMenu,
+                actions = CatanInteraction.knightActions(legal, knightMenu),
+                onDo = onSubmit,
+                onMove = onMoveKnight,
+                onCancel = onCancelKnight,
+            )
+
+        showImprove ->
+            CatanImproveDialog(
+                state = state,
+                seat = localSeat,
+                legal = legal,
+                onBuy = onSubmit,
+                onCancel = onCancelImprove,
+            )
+
+        showProgress ->
+            CatanProgressDialog(
+                hand = progressHand,
+                seats = seats,
+                onPlay = onSubmit,
+                onArm = onArmCard,
+                onCancel = onCancelProgress,
+            )
+
         showCards -> CatanPlayCardDialog(devHand, onPlay = onSubmit, onCancel = onCancelCards)
 
-        showTrade ->
-            CatanTradeDialog(
+        showTrade && state.isCk ->
+            CatanGoodsTradeDialog(
                 state = state,
                 seat = localSeat,
                 seats = seats,
@@ -394,3 +641,69 @@ private fun CatanDialogHost(
             )
     }
 }
+
+/**
+ * The dialog for the chore at the front of the queue, when it is the local
+ * player's. Chores that are answered by tapping the board (a city to lose, a
+ * metropolis site, a knight to place) have no dialog: the prompt line tells the
+ * player what to tap.
+ */
+@Composable
+private fun ChoreDialog(
+    state: CatanState,
+    localSeat: Int,
+    legal: List<CatanMove>,
+    onSubmit: (CatanMove) -> Unit,
+) {
+    val ck = state.ck ?: return
+    val check: (List<org.prolibertate.games.game.catan.Good>, (List<org.prolibertate.games.game.catan.Good>) -> CatanMove) -> Boolean =
+        { cards, make -> CatanRules.isLegalMove(state, localSeat, make(cards)) }
+    when (val chore = ck.chores.firstOrNull()) {
+        is DiscardChore -> {
+            val quota = minOf(chore.count, CatanCk.goodsCount(state, localSeat))
+            CatanGoodsPickDialog(
+                title = "Discard $quota cards",
+                intro = "Choose $quota cards to give up",
+                held = CatanCk.goodsOf(state, localSeat),
+                quota = quota,
+                confirmLabel = "Discard",
+                selectable = { true },
+                allowed = { check(it, ::DiscardGoods) },
+                onConfirm = { onSubmit(DiscardGoods(it)) },
+            )
+        }
+
+        is GiveChore -> {
+            val pool = CatanCk.goodsOf(state, localSeat).filterKeys { !chore.commoditiesOnly || it.isCommodity }
+            val quota = minOf(chore.count, pool.values.sum())
+            CatanGoodsPickDialog(
+                title = "Hand over $quota ${if (quota == 1) "card" else "cards"}",
+                intro = if (chore.commoditiesOnly) "Choose a commodity to give" else "Choose which cards to give",
+                held = pool,
+                quota = quota,
+                confirmLabel = "Give",
+                selectable = { !chore.commoditiesOnly || it.isCommodity },
+                allowed = { check(it, ::GiveGoods) },
+                onConfirm = { onSubmit(GiveGoods(it)) },
+            )
+        }
+
+        is PickDeckChore -> CatanPickDeckDialog(legal) { onSubmit(it) }
+
+        is DropProgressChore -> CatanDropProgressDialog(ck.progressHands[localSeat]) { onSubmit(it) }
+
+        is AqueductChore -> CatanAqueductDialog(legal) { onSubmit(it) }
+
+        is SpyChore -> CatanSpyDialog(ck.progressHands[chore.target], legal) { onSubmit(it) }
+
+        else -> Unit
+    }
+}
+
+/** The board spot under a dragged finger ([at], in window pixels), or null off the board. */
+private fun dragSpot(coords: LayoutCoordinates?, at: Offset?, targets: BoardTargets): CatanInteraction.Spot? {
+    if (coords == null || at == null || !coords.isAttached) return null
+    val local = coords.windowToLocal(at)
+    val layout = CatanGeometry.fit(coords.size.width.toFloat(), coords.size.height.toFloat())
+    return CatanInteraction.snap(layout, targets, Pt(local.x, local.y), layout.radius * 1.2f)
+}

app/src/main/java/org/prolibertate/games/ui/game/catan/CatanStyle.kt

@@ -3,8 +3,10 @@ package org.prolibertate.games.ui.game.catan
 import androidx.compose.runtime.Immutable
 import androidx.compose.runtime.staticCompositionLocalOf
 import androidx.compose.ui.graphics.Color
+import org.prolibertate.games.game.catan.Commodity
 import org.prolibertate.games.game.catan.Resource
 import org.prolibertate.games.game.catan.Terrain
+import org.prolibertate.games.game.catan.Track
 
 /**
  * Every visual decision for the Katan screen, in one place.
@@ -46,6 +48,19 @@ data class CatanStyle(
     val resource: Map<Resource, Color>,
     val resourceInk: Color,
 
+    // --- Cities & Knights ---------------------------------------------------
+    /** Commodity cards: cloth, coin and paper. */
+    val commodity: Map<Commodity, Color> = LightCommodities,
+    /** Ink on a commodity tile (paper is pale, so it is not white). */
+    val commodityInk: Map<Commodity, Color> = LightCommodityInk,
+    /** The colour of each improvement track, its city gate, its deck and its metropolis. */
+    val track: Map<Track, Color> = LightTracks,
+    /** Wall round a city, and the barbarian strip. */
+    val wall: Color = Color(0xFF5D4037),
+    val barbarian: Color = Color(0xFFB71C1C),
+    /** The halo round a knight that is awake. White, so it is not mistaken for the yellow tap ring. */
+    val knightReady: Color = Color(0xFFFFFFFF),
+
     // --- Players ------------------------------------------------------------
     /** One colour per seat, in seat order. Roads, settlements, cities, player strip. */
     val seats: List<Color>,
@@ -72,6 +87,25 @@ data class CatanStyle(
     val tapReach: Float = 0.55f,
     val tokenText: Float = 0.34f,
     val portText: Float = 0.27f,
+    val knightSize: Float = 0.30f,
+)
+
+private val LightCommodities = mapOf(
+    Commodity.CLOTH to Color(0xFF7E57C2),
+    Commodity.COIN to Color(0xFFF9A825),
+    Commodity.PAPER to Color(0xFFECEFF1),
+)
+
+private val LightCommodityInk = mapOf(
+    Commodity.CLOTH to Color(0xFFFFFFFF),
+    Commodity.COIN to Color(0xFF3E2723),
+    Commodity.PAPER to Color(0xFF263238),
+)
+
+private val LightTracks = mapOf(
+    Track.TRADE to Color(0xFFF2C300),
+    Track.POLITICS to Color(0xFF1E6FD9),
+    Track.SCIENCE to Color(0xFF2E9E4F),
 )
 
 /** The light palette, which is also the reference for the dark one. */

app/src/main/java/org/prolibertate/games/ui/game/catan/CatanText.kt

@@ -1,12 +1,29 @@
 package org.prolibertate.games.ui.game.catan
 
+import org.prolibertate.games.game.catan.AqueductChore
+import org.prolibertate.games.game.catan.CatanCk
 import org.prolibertate.games.game.catan.CatanPhase
 import org.prolibertate.games.game.catan.CatanRules
 import org.prolibertate.games.game.catan.CatanState
 import org.prolibertate.games.game.catan.DevCardType
+import org.prolibertate.games.game.catan.DiscardChore
+import org.prolibertate.games.game.catan.DropProgressChore
+import org.prolibertate.games.game.catan.EventFace
+import org.prolibertate.games.game.catan.GiveChore
+import org.prolibertate.games.game.catan.Good
+import org.prolibertate.games.game.catan.MetropolisChore
+import org.prolibertate.games.game.catan.PickDeckChore
+import org.prolibertate.games.game.catan.PillageChore
+import org.prolibertate.games.game.catan.PlaceKnightChore
 import org.prolibertate.games.game.catan.Port
+import org.prolibertate.games.game.catan.ProgressType
+import org.prolibertate.games.game.catan.RelocateChore
+import org.prolibertate.games.game.catan.RemoveKnightChore
 import org.prolibertate.games.game.catan.Resource
+import org.prolibertate.games.game.catan.SmithChore
+import org.prolibertate.games.game.catan.SpyChore
 import org.prolibertate.games.game.catan.Terrain
+import org.prolibertate.games.game.catan.Track
 
 /**
  * Who is who at the table, for wording. [names] may be empty or short — a
@@ -103,6 +120,10 @@ object CatanText {
     const val CONFIRM = "Confirm"
     const val STOP_ROADS = "Done with roads"
     const val BUILD = "Build"
+    const val COUNTER = "Counter…"
+    const val SEND_COUNTER = "Send counter"
+    const val EVERYONE = "Everyone"
+    const val NO_DEAL = "No deal"
 
     /**
      * The empty second line of a button that has no cost, so every button in the
@@ -118,6 +139,28 @@ object CatanText {
     const val YOU_GIVE = "You give"
     const val YOU_GET = "You get"
     const val SEND_OFFER = "Send offer"
+
+    // --- Trade board and HUD -----------------------------------------------------
+    const val TAB_PLAYER = "Player"
+    const val TAB_BANK = "Bank"
+    const val YOU_RECEIVE_ROW = "You get"
+    const val YOU_GIVE_ROW = "You give"
+    const val TRADE_HINT_PLAYER = "Tap cards to build an offer. Tap a player to address it to them alone."
+    const val TRADE_HINT_BANK = "Tap what you give, then what you want."
+    const val TRADE_HINT_BANK_EMPTY = "You do not hold enough of any one resource to trade with the bank."
+    const val TRADE_HINT_COUNTER = "Change the terms, then send them back."
+    const val HIDE = "Hide"
+    const val DENY = "Deny"
+    const val CONFIRM_BUILD = "Place"
+    const val CANCEL_BUILD = "Cancel"
+    const val DRAG_HINT = "Drag a piece onto the board"
+    const val LOG_BUTTON = "Log"
+    const val CARDS_SHORT = "Cards"
+    const val BUY_SHORT = "Buy"
+    const val ROLL_SHORT = "Roll"
+    const val END_SHORT = "End"
+    const val DONE_SHORT = "Done"
+    const val LOG_TITLE = "Table log"
     const val NO_LOG = "Nothing has happened yet."
     const val END_GAME = "End game"
     const val LOOK_AT_BOARD = "Look at the board"
@@ -136,7 +179,12 @@ object CatanText {
         seats: CatanSeats,
         setupVertexChosen: Boolean,
         building: BuildKind?,
+        /** Cities & Knights: a knight has been picked to move, and its destination is awaited. */
+        movingKnight: Boolean = false,
+        /** Cities & Knights: a progress card is waiting for a tap on the board. */
+        armed: ProgressType? = null,
     ): String {
+        if (state.isCk) return ckPrompt(state, seats, setupVertexChosen, building, movingKnight, armed)
         val me = seats.me
         val onClock = CatanRules.currentSeat(state)
         val mine = onClock == me
@@ -190,15 +238,29 @@ object CatanText {
                     "$turn is placing free roads…"
                 }
 
+            CatanPhase.CHORE -> "Waiting for ${seats.label(onClock ?: state.turn)}…"
+
             CatanPhase.TRADE_PENDING -> {
                 val offer = state.pendingTrade
                 when {
                     offer == null -> "Waiting for a reply…"
-                    offer.to == me -> "${seats.label(offer.by)} offers you a trade."
-                    offer.by == me -> "Waiting for ${seats.label(offer.to)} to answer your offer…"
-                    else -> "${seats.label(offer.by)} has offered ${seats.label(offer.to)} a trade."
+                    offer.asking == me -> if (offer.to == null) {
+                        "${seats.label(offer.by)} offers the table a trade. Accept, decline or counter."
+                    } else {
+                        "${seats.label(offer.by)} offers you a trade. Accept, decline or counter."
+                    }
+
+                    offer.by == me -> "Waiting for ${seats.label(offer.asking)} to answer your offer…"
+                    else -> "${seats.label(offer.by)}'s offer is with ${seats.label(offer.asking)}."
                 }
             }
+
+            CatanPhase.TRADE_COUNTERS ->
+                if (mine) {
+                    "Nobody accepted, but there are counter-offers. Take one or turn them down."
+                } else {
+                    "$turn is weighing counter-offers…"
+                }
         }
     }
 
@@ -212,8 +274,224 @@ object CatanText {
     fun tradeSummary(by: String, to: String, give: List<Resource>, get: List<Resource>): String =
         "$by offers ${cards(give)} to $to for ${cards(get)}"
 
+    /** One counter-offer as the offerer sees it: what that seat gives and wants. */
+    fun counterSummary(by: String, give: List<Resource>, get: List<Resource>): String =
+        "$by gives ${cards(give)} for your ${cards(get)}"
+
     fun winnerHeadline(state: CatanState, seats: CatanSeats): String {
         val winner = state.winner ?: return "Game over"
         return if (winner == seats.me) "You won!" else "${seats.label(winner)} won"
     }
+
+    // --- Cities & Knights ----------------------------------------------------
+
+    fun good(good: Good): String = when (good) {
+        Good.LUMBER -> "Lumber"
+        Good.BRICK -> "Brick"
+        Good.WOOL -> "Wool"
+        Good.GRAIN -> "Grain"
+        Good.ORE -> "Ore"
+        Good.CLOTH -> "Cloth"
+        Good.COIN -> "Coin"
+        Good.PAPER -> "Paper"
+    }
+
+    /** "2 Lumber + 1 Cloth" for a flat list of goods. */
+    fun goods(cards: List<Good>): String =
+        cards.groupingBy { it }.eachCount().entries
+            .sortedBy { it.key.ordinal }
+            .joinToString(" + ") { (g, n) -> "$n ${good(g)}" }
+            .ifEmpty { "nothing" }
+
+    fun track(track: Track): String = when (track) {
+        Track.TRADE -> "Trade"
+        Track.POLITICS -> "Politics"
+        Track.SCIENCE -> "Science"
+    }
+
+    /** What the third level of a track gives, for the improvement dialog. */
+    fun trackPower(track: Track): String = when (track) {
+        Track.TRADE -> "From level 3, trade commodities with the bank two for one."
+        Track.POLITICS -> "From level 3, knights can be promoted to mighty."
+        Track.SCIENCE -> "From level 3, when the dice pay you nothing, take any resource."
+    }
+
+    fun knightName(level: Int): String = when (level) {
+        1 -> "Basic knight"
+        2 -> "Strong knight"
+        else -> "Mighty knight"
+    }
+
+    fun event(face: EventFace?): String = when (face) {
+        null -> "–"
+        EventFace.SHIP -> "Ship"
+        EventFace.TRADE -> "Trade"
+        EventFace.POLITICS -> "Politics"
+        EventFace.SCIENCE -> "Science"
+    }
+
+    fun progress(kind: ProgressType): String = CatanCk.progressName(kind)
+
+    fun progressHelp(kind: ProgressType): String = when (kind) {
+        ProgressType.ALCHEMIST -> "Before rolling, choose what the two number dice show."
+        ProgressType.CRANE -> "Your next city improvement costs one commodity less."
+        ProgressType.ENGINEER -> "Raise a wall round one of your cities for free."
+        ProgressType.INVENTOR -> "Swap two number tokens (not 2, 6, 8 or 12)."
+        ProgressType.IRRIGATION -> "Take 2 grain for each fields hex beside your settlements and cities."
+        ProgressType.MEDICINE -> "Upgrade a settlement to a city for 2 ore and 1 grain."
+        ProgressType.MINING -> "Take 2 ore for each mountains hex beside your settlements and cities."
+        ProgressType.PRINTER -> "One victory point."
+        ProgressType.ROAD_BUILDING -> "Build two roads for free."
+        ProgressType.SMITH -> "Promote up to two of your knights one level for free."
+        ProgressType.BISHOP -> "Move the robber and take a card from every player beside its new hex."
+        ProgressType.CONSTITUTION -> "One victory point."
+        ProgressType.DESERTER -> "Another player removes a knight; you place a free one of the same strength."
+        ProgressType.DIPLOMAT -> "Remove an open road. If it was yours, build it again anywhere for free."
+        ProgressType.INTRIGUE -> "Drive an opponent's knight off a crossing beside one of your roads."
+        ProgressType.SABOTEUR -> "Every player with as many points as you or more discards half their cards."
+        ProgressType.SPY -> "Look at another player's progress cards and take one."
+        ProgressType.WARLORD -> "Wake all your knights without paying grain."
+        ProgressType.WEDDING -> "Every player with more points gives you 2 cards."
+        ProgressType.COMMERCIAL_HARBOR -> "Offer a resource to each player; each swaps it for a commodity."
+        ProgressType.MASTER_MERCHANT -> "Take 2 cards from a player with more points."
+        ProgressType.MERCHANT -> "Put the merchant beside your settlement: trade that resource 2:1 and score a point."
+        ProgressType.MERCHANT_FLEET -> "This turn, trade one chosen card type with the bank two for one."
+        ProgressType.RESOURCE_MONOPOLY -> "Name a resource. Every other player gives you 2 of it."
+        ProgressType.TRADE_MONOPOLY -> "Name a commodity. Every other player gives you 1 of it."
+    }
+
+    const val IMPROVE = "Improve"
+    const val KNIGHTS = "Knights"
+    const val CARDS_BUTTON = "Progress"
+    const val WALL = "Wall"
+    const val KNIGHT = "Knight"
+    const val STOP_SMITH = "Done promoting"
+
+    val KNIGHT_COST: String get() = cost(CatanCk.KNIGHT_COST)
+    val ACTIVATE_COST: String get() = cost(CatanCk.ACTIVATE_COST)
+    val WALL_COST: String get() = cost(CatanCk.WALL_COST)
+
+    private fun ckPrompt(
+        state: CatanState,
+        seats: CatanSeats,
+        setupVertexChosen: Boolean,
+        building: BuildKind?,
+        movingKnight: Boolean,
+        armed: ProgressType?,
+    ): String {
+        val me = seats.me
+        val onClock = CatanRules.currentSeat(state)
+        val mine = onClock == me
+        val turn = seats.label(state.turn)
+        val ck = state.ck!!
+
+        return when (state.phase) {
+            CatanPhase.GAME_OVER -> {
+                val winner = state.winner
+                if (winner == null) "The game is over." else "${seats.label(winner)} won the game."
+            }
+
+            CatanPhase.SETUP_FIRST, CatanPhase.SETUP_SECOND -> when {
+                !mine -> "${seats.label(onClock ?: state.turn)} is placing a settlement and a road…"
+                setupVertexChosen -> "Now tap the road to place beside that settlement."
+                state.phase == CatanPhase.SETUP_SECOND ->
+                    "Place your second piece: it is a city, and earns resources from the hexes around it."
+
+                else -> "Place a settlement, then a road."
+            }
+
+            CatanPhase.AWAIT_ROLL -> when {
+                !mine -> "$turn is rolling…"
+                armed != null -> armedPrompt(armed)
+                movingKnight -> "Tap where the knight should go."
+                else -> "Your turn. Roll the dice, or wake knights and play progress cards first."
+            }
+
+            CatanPhase.ROBBER -> when {
+                !mine -> "$turn is moving the robber…"
+                ck.bishop -> "The bishop: tap a hex. Everyone beside it pays you a card."
+                else -> "Move the robber. Tap a hex."
+            }
+
+            CatanPhase.PLAYING -> when {
+                !mine -> "$turn is playing…"
+                armed != null -> armedPrompt(armed)
+                movingKnight -> "Tap where the knight should go."
+                building == BuildKind.ROAD -> "Tap an edge to build a road."
+                building == BuildKind.SETTLEMENT -> "Tap an empty crossing to build a settlement."
+                building == BuildKind.CITY -> "Tap one of your settlements to upgrade it."
+                building == BuildKind.WALL -> "Tap one of your cities to raise a wall."
+                building == BuildKind.KNIGHT -> "Tap an empty crossing at the end of your road to hire a knight."
+                else -> "Your turn. Build, improve, trade, or end the turn. Tap a knight to use it."
+            }
+
+            CatanPhase.FREE_ROADS ->
+                if (mine) {
+                    "Place ${state.pendingFreeRoads} free " +
+                        if (state.pendingFreeRoads == 1) "road." else "roads."
+                } else {
+                    "$turn is placing free roads…"
+                }
+
+            CatanPhase.TRADE_PENDING -> {
+                val offer = ck.goodsOffer
+                val asking = offer?.asking?.takeIf { it >= 0 }
+                when {
+                    offer == null || asking == null -> "Waiting for a reply…"
+                    asking == me -> "${seats.label(offer.by)} offers you a trade."
+                    offer.by == me -> "Waiting for ${seats.label(asking)} to answer your offer…"
+                    else -> "${seats.label(offer.by)} has offered ${seats.label(asking)} a trade."
+                }
+            }
+
+            CatanPhase.TRADE_COUNTERS ->
+                if (mine) {
+                    "Nobody accepted, but there are counter-offers. Take one or turn them down."
+                } else {
+                    "$turn is weighing counter-offers…"
+                }
+
+            CatanPhase.DISCARDING -> "Discarding…"
+
+            CatanPhase.CHORE -> {
+                val chore = ck.chores.firstOrNull()
+                val who = seats.label(chore?.seat ?: state.turn)
+                if (chore == null || chore.seat != me) {
+                    when (chore) {
+                        is PillageChore -> "The barbarians have landed. $who must give up a city."
+                        is DiscardChore -> "$who must discard ${chore.count} cards."
+                        else -> "Waiting for $who…"
+                    }
+                } else {
+                    when (chore) {
+                        is DiscardChore -> "Discard ${chore.count} cards."
+                        is GiveChore -> "Give ${chore.count} card${if (chore.count == 1) "" else "s"} to ${seats.lower(chore.to)}."
+                        is PillageChore -> "The barbarians won. Tap a city of yours to give up."
+                        is PickDeckChore -> "Choose a progress deck to draw from."
+                        is DropProgressChore -> "You hold too many progress cards. Give one back."
+                        is MetropolisChore -> "Tap the city that will bear the ${track(chore.track).lowercase()} metropolis."
+                        is AqueductChore -> "Your aqueduct pays. Take any resource."
+                        is RelocateChore -> "Your knight was driven off. Tap where it goes."
+                        is RemoveKnightChore -> "Tap one of your knights to remove."
+                        is PlaceKnightChore -> "Tap where your free ${knightName(chore.level).lowercase()} stands."
+                        is SpyChore -> "Choose a progress card to take."
+                        is SmithChore -> "Tap a knight to promote (${chore.left} left), or stop."
+                    }
+                }
+            }
+        }
+    }
+
+    private fun armedPrompt(kind: ProgressType): String = when (kind) {
+        ProgressType.ENGINEER -> "Engineer: tap a city to wall."
+        ProgressType.MEDICINE -> "Medicine: tap a settlement to upgrade."
+        ProgressType.MERCHANT -> "Merchant: tap a hex beside one of your buildings."
+        ProgressType.DIPLOMAT -> "Diplomat: tap an open road to remove."
+        ProgressType.INTRIGUE -> "Intrigue: tap an enemy knight beside your road."
+        ProgressType.INVENTOR -> "Inventor: tap two hexes to swap their tokens."
+        else -> "Tap the board."
+    }
+
+    /** "6 steps away", "1 step away" for the barbarian ship. */
+    fun barbarianSteps(steps: Int): String = "$steps ${if (steps == 1) "step" else "steps"} away"
 }

app/src/main/java/org/prolibertate/games/ui/game/catan/CatanTradeBoard.kt

@@ -0,0 +1,415 @@
+package org.prolibertate.games.ui.game.catan
+
+import androidx.compose.foundation.background
+import androidx.compose.foundation.border
+import androidx.compose.foundation.clickable
+import androidx.compose.foundation.horizontalScroll
+import androidx.compose.foundation.layout.Arrangement
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.Row
+import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.heightIn
+import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.layout.size
+import androidx.compose.foundation.layout.width
+import androidx.compose.foundation.rememberScrollState
+import androidx.compose.foundation.shape.CircleShape
+import androidx.compose.foundation.shape.RoundedCornerShape
+import androidx.compose.material3.HorizontalDivider
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.Surface
+import androidx.compose.material3.Text
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.runtime.setValue
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.draw.alpha
+import androidx.compose.ui.draw.clip
+import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.text.font.FontWeight
+import androidx.compose.ui.unit.dp
+import androidx.compose.ui.unit.sp
+import org.prolibertate.games.game.catan.CatanMove
+import org.prolibertate.games.game.catan.CatanState
+import org.prolibertate.games.game.catan.CounterTrade
+import org.prolibertate.games.game.catan.MaritimeTrade
+import org.prolibertate.games.game.catan.OfferTrade
+import org.prolibertate.games.game.catan.Resource
+import org.prolibertate.games.game.catan.TradeOffer
+
+/*
+ * The trade board: the 2D version of Catan Universe's trade panel (see
+ * docs/RE-catan-universe.md). One panel slides up over the bottom of the board:
+ *
+ *   header   [Player | Bank]   hint                          rival buttons
+ *   top row    the cards you GET, tinted with the other side's colour
+ *   arrows
+ *   bottom row the cards you GIVE, tinted with your colour
+ *   right      ▾ hide     ✕ deny     ✓ accept
+ *
+ * Like every Katan panel it decides nothing: what may be offered is asked of
+ * [CatanInteraction], and what a bank trade costs comes from the engine's legal list.
+ */
+
+private enum class TradeMode { PLAYER, BANK }
+
+private fun Map<Resource, Int>.cards(): List<Resource> =
+    Resource.entries.flatMap { r -> List(this[r] ?: 0) { r } }
+
+/** The panel for starting a trade: with the bank, or an offer to one rival or everyone. */
+@Composable
+fun CatanTradeBoard(
+    state: CatanState,
+    seat: Int,
+    seats: CatanSeats,
+    legal: List<CatanMove>,
+    onBank: (MaritimeTrade) -> Unit,
+    onOffer: (OfferTrade) -> Unit,
+    onClose: () -> Unit,
+    modifier: Modifier = Modifier,
+    style: CatanStyle = LocalCatanStyle.current,
+) {
+    var mode by remember { mutableStateOf(TradeMode.BANK) }
+    var to by remember { mutableStateOf<Int?>(null) }
+    var give by remember { mutableStateOf(emptyMap<Resource, Int>()) }
+    var get by remember { mutableStateOf(emptyMap<Resource, Int>()) }
+    var bankGive by remember { mutableStateOf<Resource?>(null) }
+    var bankGet by remember { mutableStateOf<Resource?>(null) }
+
+    val bank = CatanInteraction.bankTrades(legal)
+    val giveCards = give.cards()
+    val getCards = get.cards()
+    val canSend = CatanInteraction.offerAllowed(state, seat, to, giveCards, getCards)
+    val bankMove = bankGive?.let { g -> bankGet?.takeIf { it in bank[g].orEmpty() }?.let { MaritimeTrade(g, it) } }
+
+    val rivals = (0 until state.playerCount).filter { it != seat }
+    val headerRight: @Composable () -> Unit = {
+        if (mode == TradeMode.PLAYER) {
+            RivalButtons(rivals, to, style, seats) { to = if (to == it) null else it }
+        }
+    }
+
+    TradeBoardFrame(
+        modifier = modifier,
+        topTint = if (mode == TradeMode.PLAYER && to != null) style.seats[to!!] else Color.Gray,
+        bottomTint = style.seats[seat],
+        header = {
+            TradeTab(CatanText.TAB_BANK, mode == TradeMode.BANK) { mode = TradeMode.BANK }
+            TradeTab(CatanText.TAB_PLAYER, mode == TradeMode.PLAYER) { mode = TradeMode.PLAYER }
+        },
+        headline = when {
+            mode == TradeMode.PLAYER -> CatanText.TRADE_HINT_PLAYER
+            bank.isEmpty() -> CatanText.TRADE_HINT_BANK_EMPTY
+            else -> CatanText.TRADE_HINT_BANK
+        },
+        headerRight = headerRight,
+        topLabel = CatanText.YOU_RECEIVE_ROW,
+        bottomLabel = CatanText.YOU_GIVE_ROW,
+        topRow = {
+            if (mode == TradeMode.PLAYER) {
+                TradeCardRow(
+                    counts = get,
+                    limit = { 9 },
+                    onChange = { get = it },
+                )
+            } else {
+                val choices = bankGive?.let { bank[it] }.orEmpty().toSet()
+                TradeCardRow(
+                    counts = bankGet?.let { mapOf(it to 1) } ?: emptyMap(),
+                    limit = { if (it in choices) 1 else 0 },
+                    enabledOf = { it in choices },
+                    onChange = {},
+                    pick = { bankGet = if (bankGet == it) null else it },
+                )
+            }
+        },
+        bottomRow = {
+            if (mode == TradeMode.PLAYER) {
+                TradeCardRow(
+                    counts = give,
+                    limit = { state.resources[seat][it] ?: 0 },
+                    onChange = { give = it },
+                )
+            } else {
+                TradeCardRow(
+                    counts = bank.keys.associateWith { CatanInteraction.bankRatio(state, seat, it) },
+                    limit = { 0 },
+                    enabledOf = { it in bank },
+                    selected = bankGive,
+                    caption = { r -> if (r in bank) "${CatanInteraction.bankRatio(state, seat, r)} : 1" else " " },
+                    onChange = {},
+                    pick = { r ->
+                        bankGive = if (bankGive == r) null else r
+                        bankGet = null
+                    },
+                )
+            }
+        },
+        acceptEnabled = if (mode == TradeMode.PLAYER) canSend else bankMove != null,
+        onAccept = {
+            if (mode == TradeMode.PLAYER) {
+                onOffer(OfferTrade(to, giveCards, getCards))
+            } else {
+                bankMove?.let(onBank)
+            }
+        },
+        denyEnabled = true,
+        onDeny = {
+            give = emptyMap()
+            get = emptyMap()
+            bankGive = null
+            bankGet = null
+            to = null
+        },
+        onHide = onClose,
+    )
+}
+
+/**
+ * The panel for an offer made to the local player: the same layout, read-only. ✓ accepts,
+ * ✕ declines, and *Counter…* turns the rows editable, pre-filled with the mirror of the offer.
+ */
+@Composable
+fun CatanTradeReplyBoard(
+    state: CatanState,
+    seat: Int,
+    offer: TradeOffer,
+    seats: CatanSeats,
+    canAccept: Boolean,
+    onAccept: () -> Unit,
+    onDecline: () -> Unit,
+    onCounter: (CounterTrade) -> Unit,
+    modifier: Modifier = Modifier,
+    style: CatanStyle = LocalCatanStyle.current,
+) {
+    var countering by remember(offer) { mutableStateOf(false) }
+    var give by remember(offer) { mutableStateOf(offer.get.groupingBy { it }.eachCount()) }
+    var get by remember(offer) { mutableStateOf(offer.give.groupingBy { it }.eachCount()) }
+    val counter = CounterTrade(give.cards(), get.cards())
+
+    TradeBoardFrame(
+        modifier = modifier,
+        topTint = style.seats[offer.by],
+        bottomTint = style.seats[seat],
+        header = {
+            TradeTab(CatanText.COUNTER, countering) { countering = !countering }
+        },
+        headline = if (countering) {
+            CatanText.TRADE_HINT_COUNTER
+        } else {
+            CatanText.tradeSummary(
+                by = seats.label(offer.by),
+                to = if (offer.to == null) "the table" else "you",
+                give = offer.give,
+                get = offer.get,
+            )
+        },
+        headerRight = {},
+        topLabel = CatanText.YOU_RECEIVE_ROW,
+        bottomLabel = CatanText.YOU_GIVE_ROW,
+        topRow = {
+            if (countering) {
+                TradeCardRow(get, limit = { state.resources[offer.by][it] ?: 0 }, onChange = { get = it })
+            } else {
+                TradeCardRow(offer.give.groupingBy { it }.eachCount(), limit = { 0 }, onChange = {})
+            }
+        },
+        bottomRow = {
+            if (countering) {
+                TradeCardRow(give, limit = { state.resources[seat][it] ?: 0 }, onChange = { give = it })
+            } else {
+                TradeCardRow(offer.get.groupingBy { it }.eachCount(), limit = { 0 }, onChange = {})
+            }
+        },
+        acceptEnabled = if (countering) {
+            CatanInteraction.counterAllowed(state, seat, counter.give, counter.get)
+        } else {
+            canAccept
+        },
+        onAccept = { if (countering) onCounter(counter) else onAccept() },
+        denyEnabled = true,
+        onDeny = onDecline,
+        onHide = null,
+    )
+}
+
+// ---------------------------------------------------------------------------
+// Pieces
+// ---------------------------------------------------------------------------
+
+@Composable
+private fun TradeBoardFrame(
+    topTint: Color,
+    bottomTint: Color,
+    header: @Composable () -> Unit,
+    headline: String,
+    headerRight: @Composable () -> Unit,
+    topLabel: String,
+    bottomLabel: String,
+    topRow: @Composable () -> Unit,
+    bottomRow: @Composable () -> Unit,
+    acceptEnabled: Boolean,
+    onAccept: () -> Unit,
+    denyEnabled: Boolean,
+    onDeny: () -> Unit,
+    onHide: (() -> Unit)?,
+    modifier: Modifier = Modifier,
+) {
+    Surface(
+        modifier = modifier.fillMaxWidth(),
+        shape = RoundedCornerShape(topStart = 18.dp, topEnd = 18.dp),
+        color = MaterialTheme.colorScheme.surface.copy(alpha = 0.97f),
+        tonalElevation = 6.dp,
+        shadowElevation = 12.dp,
+    ) {
+        Row(Modifier.padding(horizontal = 12.dp, vertical = 8.dp)) {
+            Column(Modifier.weight(1f), verticalArrangement = Arrangement.spacedBy(6.dp)) {
+                Row(verticalAlignment = Alignment.CenterVertically, horizontalArrangement = Arrangement.spacedBy(8.dp)) {
+                    header()
+                    Text(
+                        headline,
+                        style = MaterialTheme.typography.bodySmall,
+                        // Two lines, always: the panel keeps its height whatever is said.
+                        minLines = 2,
+                        maxLines = 2,
+                        modifier = Modifier.weight(1f),
+                    )
+                    headerRight()
+                }
+                HorizontalDivider()
+                TintedRow(topTint, topLabel, topRow)
+                Text("⇣   ⇣   ⇣", modifier = Modifier.align(Alignment.CenterHorizontally), fontSize = 14.sp)
+                TintedRow(bottomTint, bottomLabel, bottomRow)
+            }
+            Column(
+                modifier = Modifier.padding(start = 10.dp).width(72.dp),
+                verticalArrangement = Arrangement.spacedBy(6.dp, Alignment.CenterVertically),
+                horizontalAlignment = Alignment.CenterHorizontally,
+            ) {
+                // Always three slots, so the column does not shift when there is nothing to hide.
+                if (onHide != null) {
+                    HudRoundButton("▾", caption = CatanText.HIDE, diameter = 48.dp, onClick = onHide)
+                } else {
+                    Box(Modifier.size(48.dp))
+                }
+                HudRoundButton("✕", caption = CatanText.DENY, enabled = denyEnabled, tint = Color(0xFFC62828), diameter = 52.dp, onClick = onDeny)
+                HudRoundButton("✓", caption = CatanText.ACCEPT, enabled = acceptEnabled, tint = Color(0xFF2E7D32), diameter = 60.dp, onClick = onAccept)
+            }
+        }
+    }
+}
+
+@Composable
+private fun TintedRow(tint: Color, label: String, content: @Composable () -> Unit) {
+    val shape = RoundedCornerShape(12.dp)
+    Column(
+        Modifier
+            .fillMaxWidth()
+            .clip(shape)
+            .background(tint.copy(alpha = 0.18f))
+            .border(1.dp, tint.copy(alpha = 0.5f), shape)
+            .padding(horizontal = 8.dp, vertical = 4.dp),
+    ) {
+        Text(label, fontSize = 10.sp, fontWeight = FontWeight.Bold)
+        Box(Modifier.horizontalScroll(rememberScrollState())) { content() }
+    }
+}
+
+/**
+ * Five resource cards in a row. Tapping a card adds one (up to [limit]); the "−" under it
+ * takes one back. A bank row passes [pick] instead, and a tap selects the card.
+ */
+@Composable
+private fun TradeCardRow(
+    counts: Map<Resource, Int>,
+    limit: (Resource) -> Int,
+    onChange: (Map<Resource, Int>) -> Unit,
+    enabledOf: (Resource) -> Boolean = { true },
+    selected: Resource? = null,
+    caption: ((Resource) -> String)? = null,
+    pick: ((Resource) -> Unit)? = null,
+) {
+    Row(horizontalArrangement = Arrangement.spacedBy(8.dp)) {
+        Resource.entries.forEach { resource ->
+            val n = counts[resource] ?: 0
+            Column(horizontalAlignment = Alignment.CenterHorizontally) {
+                ResourceTile(
+                    resource = resource,
+                    count = n,
+                    selected = selected == resource,
+                    enabled = enabledOf(resource) && (pick != null || n > 0 || limit(resource) > 0),
+                    onClick = {
+                        if (pick != null) {
+                            pick(resource)
+                        } else if (n < limit(resource)) {
+                            onChange(counts + (resource to n + 1))
+                        }
+                    },
+                )
+                if (caption != null) {
+                    Text(caption(resource), fontSize = 11.sp, fontWeight = FontWeight.Bold)
+                } else {
+                    // Always laid out so the row never changes height.
+                    Text(
+                        "−",
+                        fontSize = 20.sp,
+                        fontWeight = FontWeight.Bold,
+                        modifier = Modifier
+                            .alpha(if (n > 0 && pick == null && limit(resource) >= 0) 1f else 0f)
+                            .clickable(enabled = n > 0 && pick == null) {
+                                onChange(counts + (resource to n - 1))
+                            }
+                            .padding(horizontal = 14.dp),
+                    )
+                }
+            }
+        }
+    }
+}
+
+@Composable
+private fun TradeTab(label: String, selected: Boolean, onClick: () -> Unit) {
+    val shape = RoundedCornerShape(50)
+    Text(
+        label,
+        fontSize = 13.sp,
+        fontWeight = FontWeight.Bold,
+        color = if (selected) MaterialTheme.colorScheme.onPrimary else MaterialTheme.colorScheme.onSurface,
+        modifier = Modifier
+            .clip(shape)
+            .background(if (selected) MaterialTheme.colorScheme.primary else MaterialTheme.colorScheme.surfaceVariant)
+            .clickable(onClick = onClick)
+            .padding(horizontal = 14.dp, vertical = 8.dp),
+    )
+}
+
+/** One round button per rival: tap to address the offer to them alone, tap again for everyone. */
+@Composable
+private fun RivalButtons(
+    rivals: List<Int>,
+    chosen: Int?,
+    style: CatanStyle,
+    seats: CatanSeats,
+    onTap: (Int) -> Unit,
+) {
+    Row(horizontalArrangement = Arrangement.spacedBy(6.dp)) {
+        rivals.forEach { rival ->
+            val picked = chosen == rival
+            Box(
+                Modifier
+                    .size(40.dp)
+                    .clip(CircleShape)
+                    .background(style.seats[rival])
+                    .border(if (picked) 4.dp else 1.dp, if (picked) Color.White else Color(0x55000000), CircleShape)
+                    .clickable { onTap(rival) },
+                contentAlignment = Alignment.Center,
+            ) {
+                Text(seats.label(rival).take(1).uppercase(), color = Color.White, fontWeight = FontWeight.Bold, fontSize = 14.sp)
+            }
+        }
+    }
+}

app/src/test/java/org/prolibertate/games/game/CatalogTest.kt

@@ -106,30 +106,33 @@ class CatalogTest {
     }
 
     @Test
-    fun `every reference game in the catalogue can be played`() {
-        // Every game the app ships is playable. The one exception is Katan,
-        // listed so the slot exists and marked *Coming soon* until its engine
-        // and screen land — `available = false` is what keeps an unfinished
-        // game out of a production build while leaving it visible on a dev one.
-        assertEquals(
-            listOf(GameCatalog.CATAN),
-            GameCatalog.all.filterNot { it.available }.map { it.id },
-        )
-        // It is also the only difference the two channels see in a menu.
-        val hiddenFromProduction = GameCatalog.inMenu(GameMenu.BOARD, includeComingSoon = true) -
-            GameCatalog.inMenu(GameMenu.BOARD, includeComingSoon = false)
-        assertEquals(listOf(GameCatalog.byId(GameCatalog.CATAN)!!), hiddenFromProduction)
+    fun `every game in the catalogue can be played`() {
+        // `available` is the release gate. Nothing is held back at the moment,
+        // so a production menu lists every game; a game parked behind the gate
+        // belongs in `devPreview`, and must say so rather than being quietly
+        // unavailable everywhere.
+        GameCatalog.all.filterNot { it.available }.forEach { game ->
+            assertTrue("${game.id} is unavailable but not a dev preview", game.devPreview)
+        }
+        GameMenu.entries.forEach { menu ->
+            val held = GameCatalog.inMenu(menu, includeComingSoon = true) -
+                GameCatalog.inMenu(menu, includeComingSoon = false).toSet()
+            held.forEach { assertTrue("${it.id} hidden from production without a preview flag", it.devPreview) }
+        }
     }
 
     @Test
     fun `a preview game opens on a dev build and nowhere else`() {
-        val preview = GameCatalog.all.filter { it.devPreview }
-        assertTrue("Katan is the preview game", preview.map { it.id } == listOf(GameCatalog.CATAN))
-        preview.forEach { game ->
+        GameCatalog.all.filter { it.devPreview }.forEach { game ->
             assertFalse("${game.id}: preview is for games that are not yet available", game.available)
             assertTrue("${game.id} should open on a dev build", game.playableIn(devBuild = true))
             assertFalse("${game.id} must not open in production", game.playableIn(devBuild = false))
         }
+        // The two games that were once previews now open everywhere.
+        listOf(GameCatalog.CATAN, GameCatalog.MEOWDOKU).forEach { id ->
+            val game = GameCatalog.byId(id)!!
+            assertTrue("$id should open in production", game.playableIn(devBuild = false))
+        }
         // An ordinary finished game opens everywhere.
         val chess = GameCatalog.byId(GameCatalog.CHESS)!!
         assertTrue(chess.playableIn(devBuild = true) && chess.playableIn(devBuild = false))
@@ -174,6 +177,8 @@ class CatalogTest {
                 GameCatalog.MASTERMIND,
                 GameCatalog.BACKGAMMON,
                 GameCatalog.PIRATES,
+                GameCatalog.CATAN,
+                GameCatalog.MEOWDOKU,
             ),
             GameCatalog.playable.map { it.id }.toSet(),
         )

app/src/test/java/org/prolibertate/games/game/catan/CatanAiTest.kt

@@ -142,4 +142,50 @@ class CatanAiTest {
         assertEquals(CatanPhase.PLAYING, after.phase)
         assertNull(after.pendingTrade)
     }
+
+    private fun tradeTable(offer: TradeOffer, vararg hands: Map<Resource, Int>): CatanState =
+        CatanRules.initialState(config(CatanOptions(), seed = 7L)).copy(
+            phase = CatanPhase.TRADE_PENDING,
+            turn = 0,
+            turnNumber = 1,
+            pendingTrade = offer,
+            resources = hands.toList(),
+        )
+
+    @Test
+    fun `the AI accepts an offer that gives it more than it costs, and declines the reverse`() {
+        val generous = tradeTable(
+            TradeOffer(by = 0, to = null, give = listOf(Resource.ORE, Resource.ORE), get = listOf(Resource.WOOL), asking = 1),
+            hand(Resource.ORE to 2), hand(Resource.WOOL to 2), hand(),
+        )
+        assertEquals(AcceptTrade, CatanAi().chooseMove(generous, 1, CatanRules.legalMoves(generous, 1)))
+
+        val stingy = tradeTable(
+            TradeOffer(by = 0, to = null, give = listOf(Resource.WOOL), get = listOf(Resource.ORE), asking = 1),
+            hand(Resource.WOOL to 1), hand(Resource.ORE to 2), hand(),
+        )
+        assertEquals(DeclineTrade, CatanAi().chooseMove(stingy, 1, CatanRules.legalMoves(stingy, 1)))
+    }
+
+    @Test
+    fun `an AI offerer takes the best counter and refuses a losing one`() {
+        val counters = listOf(
+            TradeCounter(by = 1, give = listOf(Resource.ORE), get = listOf(Resource.LUMBER)),
+            TradeCounter(by = 2, give = listOf(Resource.ORE, Resource.GRAIN), get = listOf(Resource.WOOL)),
+        )
+        val state = tradeTable(
+            TradeOffer(by = 0, to = null, give = listOf(Resource.WOOL), get = listOf(Resource.ORE), asking = -1, counters = counters),
+            hand(Resource.LUMBER to 1, Resource.WOOL to 1), hand(Resource.ORE to 1), hand(Resource.ORE to 1, Resource.GRAIN to 1),
+        ).copy(phase = CatanPhase.TRADE_COUNTERS)
+        val legal = CatanRules.legalMoves(state, 0)
+        assertEquals(AcceptCounter(2), CatanAi().chooseMove(state, 0, legal))
+
+        val bad = state.copy(
+            pendingTrade = state.pendingTrade!!.copy(
+                counters = listOf(TradeCounter(by = 1, give = listOf(Resource.WOOL), get = listOf(Resource.LUMBER))),
+            ),
+            resources = listOf(hand(Resource.LUMBER to 1), hand(Resource.WOOL to 1), hand()),
+        )
+        assertEquals(DismissCounters, CatanAi().chooseMove(bad, 0, CatanRules.legalMoves(bad, 0)))
+    }
 }

app/src/test/java/org/prolibertate/games/game/catan/CatanCkSelfPlayTest.kt

@@ -0,0 +1,182 @@
+package org.prolibertate.games.game.catan
+
+import kotlinx.serialization.encodeToString
+import kotlinx.serialization.json.Json
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertTrue
+import org.junit.Test
+import org.prolibertate.games.game.GameCatalog
+import org.prolibertate.games.game.engine.PlayerKind
+import org.prolibertate.games.game.engine.PlayerSlot
+import org.prolibertate.games.game.engine.TableConfig
+
+/**
+ * Engines playing Cities & Knights against each other. These are the
+ * playtests: every move is checked for legality, the state is round-tripped
+ * through its wire format as it goes, nothing may leave a seat without a move,
+ * and the game has to reach a result.
+ */
+class CatanCkSelfPlayTest {
+
+    private val json = Json { encodeDefaults = true }
+
+    private fun config(options: CatanOptions, seed: Long) = TableConfig(
+        gameId = GameCatalog.CATAN,
+        seats = (0 until options.playerCount).map {
+            PlayerSlot(seat = it, name = "P$it", kind = PlayerKind.AI, team = it)
+        },
+        optionsJson = json.encodeToString(options),
+        seed = seed,
+    )
+
+    /** What one game looked like, for the summary printed at the end. */
+    private data class Report(
+        val seed: Long,
+        val moves: Int,
+        val turns: Int,
+        val attacks: Int,
+        val progressPlayed: Int,
+        val metropolises: Int,
+        val winner: Int?,
+        val points: List<Int>,
+    )
+
+    private fun playOut(options: CatanOptions, seed: Long, cap: Int = 30_000): Pair<CatanState, Report> {
+        val ai = CatanAi()
+        var state = CatanRules.initialState(config(options, seed))
+        var moves = 0
+        var attacks = 0
+        var progress = 0
+        while (!CatanRules.isFinished(state)) {
+            assertTrue("seed $seed ran past $cap moves; log tail: ${state.log.takeLast(8)}", moves++ < cap)
+            val seat = CatanRules.currentSeat(state)
+                ?: error("seed $seed: nobody on the clock in ${state.phase}; log tail: ${state.log.takeLast(8)}")
+            val legal = CatanRules.legalMoves(state, seat)
+            assertTrue("seed $seed: seat $seat has no legal move in ${state.phase}", legal.isNotEmpty())
+            val move = ai.chooseMove(state, seat, legal)
+            assertTrue(
+                "seed $seed: seat $seat chose the illegal move $move in ${state.phase}; " +
+                    "log tail: ${state.log.takeLast(5)}",
+                CatanRules.isLegalMove(state, seat, move),
+            )
+            val before = state.ck!!.attacked
+            val wasAttacks = state.log.count { it.contains("The barbarians land") }
+            state = CatanRules.applyMove(state, seat, move)
+            attacks += state.log.count { it.contains("The barbarians land") } - wasAttacks
+            if (move is PlayProgress) progress++
+            if (!before && state.ck!!.attacked) Unit
+
+            if (moves % 97 == 0) {
+                val back = CatanRules.decodeState(CatanRules.encodeState(state))
+                assertEquals("seed $seed: the state did not survive its wire format", state, back)
+                // A seat's view never carries another seat's progress cards or the decks.
+                for (viewer in 0 until options.playerCount) {
+                    val view = CatanRules.viewFor(state, viewer)
+                    assertTrue(view.ck!!.decks.values.all { it.isEmpty() })
+                    for (other in 0 until options.playerCount) {
+                        if (other != viewer) {
+                            val spied = (state.ck!!.chores.firstOrNull() as? SpyChore)
+                            val allowed = spied != null && spied.seat == viewer && spied.target == other
+                            if (!allowed) assertTrue(view.ck!!.progressHands[other].isEmpty())
+                        }
+                    }
+                }
+            }
+            checkInvariants(state, seed)
+        }
+        val ck = state.ck!!
+        return state to Report(
+            seed = seed,
+            moves = moves,
+            turns = state.turnNumber,
+            attacks = attacks,
+            progressPlayed = progress,
+            metropolises = ck.metropolises.size,
+            winner = state.winner,
+            points = CatanRules.publicVictoryPoints(state),
+        )
+    }
+
+    /** Things that must hold in every state of every game. */
+    private fun checkInvariants(state: CatanState, seed: Long) {
+        val ck = state.ck!!
+        val tag = "seed $seed turn ${state.turnNumber}"
+        // Cards are conserved: no good is held in more copies than the bank started with.
+        for (good in Good.entries) {
+            val held = (0 until state.playerCount).sumOf { CatanCk.goodsOf(state, it)[good] ?: 0 }
+            val cap = if (good.isCommodity) BANK_PER_COMMODITY else BANK_PER_RESOURCE
+            assertTrue("$tag: $held ${good} cards exist, the bank only had $cap", held in 0..cap)
+        }
+        for (seat in 0 until state.playerCount) {
+            assertTrue(
+                "$tag: seat $seat holds negative cards",
+                CatanCk.goodsOf(state, seat).values.all { it >= 0 },
+            )
+            for (level in 1..3) {
+                assertTrue(
+                    "$tag: seat $seat has more than two level-$level knights",
+                    ck.knights.count { it.owner == seat && it.level == level } <= KNIGHTS_PER_LEVEL,
+                )
+            }
+            assertTrue("$tag: too many progress cards in seat $seat's hand", ck.progressHands[seat].size <= PROGRESS_HAND_MAX + 1)
+            assertTrue("$tag: seat $seat has more than three walls", CatanCk.wallsOf(state, seat) <= MAX_WALLS)
+            assertTrue(
+                "$tag: seat $seat has more than five settlements",
+                state.buildings.count { it == CatanBuilding(BuildingType.SETTLEMENT, seat) } <= MAX_SETTLEMENTS,
+            )
+            assertTrue(
+                "$tag: seat $seat has more than four cities",
+                state.buildings.count { it == CatanBuilding(BuildingType.CITY, seat) } <= MAX_CITIES,
+            )
+        }
+        // A knight stands on a crossing nothing else stands on, and no two share one.
+        assertEquals("$tag: two knights share a crossing", ck.knights.size, ck.knights.map { it.vertex }.toSet().size)
+        for (k in ck.knights) {
+            assertTrue("$tag: a knight stands on a building at ${k.vertex}", state.buildings[k.vertex] == null)
+        }
+        // Metropolises stand on cities of their owners.
+        for ((_, m) in ck.metropolises) {
+            assertEquals(
+                "$tag: a metropolis is not on its owner's city",
+                CatanBuilding(BuildingType.CITY, m.seat),
+                state.buildings[m.vertex],
+            )
+        }
+        // Every progress card exists exactly once, in a deck or a hand, or was played face up.
+        val cards = ck.decks.values.sumOf { it.size } + ck.progressHands.sumOf { it.size } + ck.progressVp.sum()
+        assertEquals("$tag: progress cards were lost or duplicated", 54, cards)
+        assertTrue("$tag: barbarians out of range", ck.barbarians in 1..BARBARIAN_STEPS)
+    }
+
+    @Test
+    fun `three engines play Cities and Knights to a finish`() {
+        val reports = (1L..12L).map { seed ->
+            val (state, report) = playOut(
+                CatanOptions(playerCount = 3, pointsToWin = 13, ruleSet = CatanRuleSet.CITIES_AND_KNIGHTS),
+                seed,
+            )
+            assertEquals("seed $seed", CatanPhase.GAME_OVER, state.phase)
+            val winner = state.winner
+            assertTrue("seed $seed finished without a winner", winner != null)
+            assertTrue(
+                "seed $seed: the winner fell short of the target",
+                CatanRules.victoryPoints(state, winner!!) >= 13,
+            )
+            report
+        }
+        reports.forEach { println("CK3 $it") }
+    }
+
+    @Test
+    fun `four engines play Cities and Knights to a finish`() {
+        val reports = (101L..108L).map { seed ->
+            val (state, report) = playOut(
+                CatanOptions(playerCount = 4, pointsToWin = 13, ruleSet = CatanRuleSet.CITIES_AND_KNIGHTS),
+                seed,
+            )
+            assertEquals("seed $seed", CatanPhase.GAME_OVER, state.phase)
+            report
+        }
+        reports.forEach { println("CK4 $it") }
+    }
+}

app/src/test/java/org/prolibertate/games/game/catan/CatanRulesTest.kt

@@ -520,6 +520,113 @@ class CatanRulesTest {
         assertEquals(listOf<CatanMove>(DeclineTrade), CatanRules.legalMoves(offered, 1))
     }
 
+    private val twoLumberForBrick =
+        OfferTrade(to = null, give = listOf(Resource.LUMBER, Resource.LUMBER), get = listOf(Resource.BRICK))
+
+    private fun openTable() = craft().copy(
+        resources = hands(
+            hand(Resource.LUMBER to 3),
+            hand(Resource.BRICK to 2),
+            hand(Resource.BRICK to 1, Resource.WOOL to 1),
+        ),
+    )
+
+    @Test
+    fun `an open offer asks each other seat in turn until one accepts`() {
+        val state = openTable()
+        assertTrue(CatanRules.isLegalMove(state, 0, twoLumberForBrick))
+        val asked1 = CatanRules.applyMove(state, 0, twoLumberForBrick)
+        assertEquals(CatanPhase.TRADE_PENDING, asked1.phase)
+        assertEquals(1, CatanRules.currentSeat(asked1))
+
+        val asked2 = CatanRules.applyMove(asked1, 1, DeclineTrade)
+        assertEquals("a decline passes the offer on", 2, CatanRules.currentSeat(asked2))
+        assertEquals(CatanPhase.TRADE_PENDING, asked2.phase)
+
+        val done = CatanRules.applyMove(asked2, 2, AcceptTrade)
+        assertEquals(CatanPhase.PLAYING, done.phase)
+        assertNull(done.pendingTrade)
+        assertEquals(hand(Resource.LUMBER to 1, Resource.BRICK to 1), done.resources[0])
+        assertEquals(hand(Resource.LUMBER to 2, Resource.WOOL to 1), done.resources[2])
+        assertEquals("seat 1 never took part", state.resources[1], done.resources[1])
+    }
+
+    @Test
+    fun `an open offer nobody wants lapses back to the offerer`() {
+        var table = CatanRules.applyMove(openTable(), 0, twoLumberForBrick)
+        table = CatanRules.applyMove(table, 1, DeclineTrade)
+        table = CatanRules.applyMove(table, 2, DeclineTrade)
+        assertEquals(CatanPhase.PLAYING, table.phase)
+        assertNull(table.pendingTrade)
+        assertEquals(0, CatanRules.currentSeat(table))
+    }
+
+    @Test
+    fun `seats with no cards are not asked`() {
+        val state = openTable().copy(resources = hands(hand(Resource.LUMBER to 3), hand(), hand(Resource.BRICK to 1)))
+        val table = CatanRules.applyMove(state, 0, twoLumberForBrick)
+        assertEquals(2, CatanRules.currentSeat(table))
+    }
+
+    @Test
+    fun `a counter is kept and the offerer chooses once everyone has answered`() {
+        var table = CatanRules.applyMove(openTable(), 0, twoLumberForBrick)
+        // Seat 1 will not give a brick for two lumber but would for three.
+        val counter = CounterTrade(give = listOf(Resource.BRICK), get = listOf(Resource.LUMBER, Resource.LUMBER, Resource.LUMBER))
+        assertTrue(CatanRules.isLegalMove(table, 1, counter))
+        table = CatanRules.applyMove(table, 1, counter)
+        assertEquals(2, CatanRules.currentSeat(table))
+        table = CatanRules.applyMove(table, 2, DeclineTrade)
+
+        assertEquals(CatanPhase.TRADE_COUNTERS, table.phase)
+        assertEquals("the offerer chooses", 0, CatanRules.currentSeat(table))
+        assertEquals(
+            listOf<CatanMove>(AcceptCounter(1), DismissCounters),
+            CatanRules.legalMoves(table, 0),
+        )
+
+        val taken = CatanRules.applyMove(table, 0, AcceptCounter(1))
+        assertEquals(CatanPhase.PLAYING, taken.phase)
+        assertNull(taken.pendingTrade)
+        assertEquals(hand(Resource.BRICK to 1), taken.resources[0])
+        assertEquals(hand(Resource.LUMBER to 3, Resource.BRICK to 1), taken.resources[1])
+    }
+
+    @Test
+    fun `counters can all be turned down`() {
+        var table = CatanRules.applyMove(openTable(), 0, twoLumberForBrick)
+        table = CatanRules.applyMove(
+            table, 1,
+            CounterTrade(listOf(Resource.BRICK), listOf(Resource.LUMBER, Resource.LUMBER, Resource.LUMBER)),
+        )
+        table = CatanRules.applyMove(table, 2, DeclineTrade)
+        val after = CatanRules.applyMove(table, 0, DismissCounters)
+        assertEquals(CatanPhase.PLAYING, after.phase)
+        assertNull(after.pendingTrade)
+        assertEquals(openTable().resources, after.resources)
+    }
+
+    @Test
+    fun `a counter must differ from the offer and be affordable`() {
+        val table = CatanRules.applyMove(openTable(), 0, twoLumberForBrick)
+        assertFalse(
+            "the offer as made is an accept, not a counter",
+            CatanRules.isLegalMove(table, 1, CounterTrade(listOf(Resource.BRICK), listOf(Resource.LUMBER, Resource.LUMBER))),
+        )
+        assertFalse(
+            "cannot promise cards not held",
+            CatanRules.isLegalMove(table, 1, CounterTrade(listOf(Resource.ORE), listOf(Resource.LUMBER))),
+        )
+        assertFalse(
+            "cannot ask for cards the offerer lacks",
+            CatanRules.isLegalMove(table, 1, CounterTrade(listOf(Resource.BRICK), listOf(Resource.ORE))),
+        )
+        assertFalse(
+            "only the seat being asked may counter",
+            CatanRules.isLegalMove(table, 2, CounterTrade(listOf(Resource.WOOL), listOf(Resource.LUMBER))),
+        )
+    }
+
     @Test
     fun `the bank trades four for one and harbours do better`() {
         val base = craft()
@@ -912,6 +1019,10 @@ class CatanRulesTest {
             OfferTrade(1, listOf(Resource.LUMBER, Resource.LUMBER), listOf(Resource.ORE)),
             AcceptTrade,
             DeclineTrade,
+            OfferTrade(null, listOf(Resource.LUMBER), listOf(Resource.ORE)),
+            CounterTrade(listOf(Resource.WOOL), listOf(Resource.GRAIN, Resource.GRAIN)),
+            AcceptCounter(2),
+            DismissCounters,
             MaritimeTrade(Resource.WOOL, Resource.GRAIN),
             EndTurn,
             EndFreeRoads,

app/src/test/java/org/prolibertate/games/game/engine/SavedGameStoreTest.kt

@@ -0,0 +1,119 @@
+package org.prolibertate.games.game.engine
+
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertFalse
+import org.junit.Assert.assertNull
+import org.junit.Assert.assertTrue
+import org.junit.Rule
+import org.junit.Test
+import org.junit.rules.TemporaryFolder
+import java.io.File
+
+class SavedGameStoreTest {
+
+    @get:Rule
+    val folder = TemporaryFolder()
+
+    private fun store() = SavedGameStore(File(folder.root, "saves"))
+
+    private fun match(gameId: String = "chess", state: String = "{\"turn\":1}", at: Long = 1_000L) = SavedMatch(
+        gameId = gameId,
+        config = TableConfig(
+            gameId = gameId,
+            seats = listOf(
+                PlayerSlot(0, "You", PlayerKind.HUMAN_LOCAL, 0),
+                PlayerSlot(1, "Computer", PlayerKind.AI, 1),
+            ),
+            optionsJson = "{}",
+            seed = 42L,
+        ),
+        localSeat = 0,
+        stateJson = state,
+        savedAtMillis = at,
+        summary = "White to move",
+    )
+
+    @Test
+    fun `a saved game comes back exactly as it went in`() {
+        val s = store()
+        s.save(match())
+        assertEquals(match(), s.load("chess"))
+    }
+
+    @Test
+    fun `there is nothing to load before anything is saved`() {
+        assertNull(store().load("chess"))
+        assertTrue(store().all().isEmpty())
+    }
+
+    @Test
+    fun `a game keeps one slot, and saving again replaces it`() {
+        val s = store()
+        s.save(match(state = "one", at = 1))
+        s.save(match(state = "two", at = 2))
+        assertEquals("two", s.load("chess")!!.stateJson)
+        assertEquals(1, s.all().size)
+    }
+
+    @Test
+    fun `clearing forgets the game and leaves the others`() {
+        val s = store()
+        s.save(match("chess"))
+        s.save(match("golf"))
+        s.clear("chess")
+        assertNull(s.load("chess"))
+        assertEquals("golf", s.load("golf")!!.gameId)
+        s.clear("chess") // clearing nothing is fine
+    }
+
+    @Test
+    fun `the most recently played game is listed first`() {
+        val s = store()
+        s.save(match("chess", at = 10))
+        s.save(match("golf", at = 30))
+        s.save(match("catan", at = 20))
+        assertEquals(listOf("golf", "catan", "chess"), s.all().map { it.gameId })
+    }
+
+    @Test
+    fun `a file that cannot be read is dropped rather than thrown`() {
+        val s = store()
+        s.save(match())
+        File(folder.root, "saves/chess.json").writeText("{ this is not json")
+        assertNull(s.load("chess"))
+        assertFalse(File(folder.root, "saves/chess.json").exists())
+    }
+
+    @Test
+    fun `a file holding another game is not served as this one`() {
+        val s = store()
+        s.save(match("golf"))
+        File(folder.root, "saves/golf.json").copyTo(File(folder.root, "saves/chess.json"))
+        assertNull(s.load("chess"))
+    }
+
+    @Test
+    fun `a save that was cut off half way leaves the previous position`() {
+        val s = store()
+        s.save(match(state = "good"))
+        // What a kill mid-write leaves behind: a stray temporary file.
+        File(folder.root, "saves/chess.json.tmp").writeText("{ half a wri")
+        assertEquals("good", s.load("chess")!!.stateJson)
+        assertEquals(1, s.all().size)
+    }
+
+    @Test
+    fun `a game id cannot climb out of the folder`() {
+        val bad = runCatching { store().load("../secret") }
+        assertTrue(bad.isFailure)
+    }
+
+    @Test
+    fun `an unknown field from a newer build does not stop a save loading`() {
+        val s = store()
+        s.save(match())
+        val file = File(folder.root, "saves/chess.json")
+        file.writeText(file.readText().replaceFirst("{", "{\"addedLater\":true,"))
+        assertEquals("chess", s.load("chess")!!.gameId)
+    }
+}

app/src/test/java/org/prolibertate/games/game/meowdoku/MeowdokuRulesTest.kt

@@ -0,0 +1,343 @@
+package org.prolibertate.games.game.meowdoku
+
+import kotlinx.serialization.encodeToString
+import kotlinx.serialization.json.Json
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertFalse
+import org.junit.Assert.assertNotNull
+import org.junit.Assert.assertNull
+import org.junit.Assert.assertThrows
+import org.junit.Assert.assertTrue
+import org.junit.Test
+import org.prolibertate.games.game.engine.PlayerKind
+import org.prolibertate.games.game.engine.PlayerSlot
+import org.prolibertate.games.game.engine.TableConfig
+
+/**
+ * The puzzle, the generator, and the referee.
+ *
+ * The generator is where a wrong board would hurt most — a second answer makes
+ * the deduction unfair and the hearts a lottery — so the generation tests run
+ * over seeds rather than one lucky one.
+ */
+class MeowdokuRulesTest {
+
+    private val json = Json { encodeDefaults = true }
+
+    private fun soloConfig(options: MeowdokuOptions, seed: Long = 7L) = TableConfig(
+        gameId = "meowdoku",
+        seats = listOf(PlayerSlot(seat = 0, name = "P0", kind = PlayerKind.HUMAN_LOCAL, team = 0)),
+        optionsJson = json.encodeToString(options),
+        seed = seed,
+    )
+
+    private fun dealt(side: Int, seed: Long = 7L) =
+        MeowdokuRules.initialState(soloConfig(MeowdokuOptions(side = side), seed))
+
+    /**
+     * A puzzle that must exist, named so the assertions below read as facts
+     * rather than as unwrapping.
+     */
+    private fun <T> required(value: T?, message: String): T {
+        assertNotNull(message, value)
+        @Suppress("UNCHECKED_CAST")
+        return value as T
+    }
+
+    // ---- generator ---------------------------------------------------------
+
+    @Test
+    fun `every dealt board has exactly one answer`() {
+        for (side in 4..8) {
+            for (seed in 1L..6L) {
+                val puzzle = required(
+                    MeowdokuGenerator.generate(side, seed),
+                    "no puzzle for side $side seed $seed",
+                )
+                assertEquals(
+                    "the $side board dealt from seed $seed has more than one answer",
+                    1,
+                    MeowdokuGenerator.countSolutions(side, puzzle.regions),
+                )
+            }
+        }
+    }
+
+    @Test
+    fun `the same seed deals the same board`() {
+        val a = MeowdokuGenerator.generate(6, 12345L)
+        val b = MeowdokuGenerator.generate(6, 12345L)
+        assertEquals(a, b)
+    }
+
+    @Test
+    fun `the answer satisfies the cats' own rules`() {
+        for (seed in 0L..20L) {
+            val puzzle = required(MeowdokuGenerator.generate(7, seed), "no puzzle for seed $seed")
+            val cats = puzzle.solutionSquares()
+            assertEquals(7, cats.size)
+            assertEquals(7, cats.map { it.first }.distinct().size)
+            assertEquals(7, cats.map { it.second }.distinct().size)
+            for (i in cats.indices) {
+                for (j in i + 1 until cats.size) {
+                    val (r1, c1) = cats[i]
+                    val (r2, c2) = cats[j]
+                    val touches = kotlin.math.abs(r1 - r2) <= 1 && kotlin.math.abs(c1 - c2) <= 1
+                    assertFalse("cats $cats touch", touches)
+                    assertFalse("two cats share a colour", puzzle.regionOf(r1, c1) == puzzle.regionOf(r2, c2))
+                }
+            }
+        }
+    }
+
+    @Test
+    fun `every colour owns exactly one cat and is contiguous`() {
+        val puzzle = required(MeowdokuGenerator.generate(6, 99L), "no puzzle for seed 99")
+        val cells = (0 until 6).flatMap { r -> (0 until 6).map { c -> r to c } }
+
+        val owned = (0 until 6).map { region ->
+            cells.filter { (r, c) -> puzzle.regionOf(r, c) == region }
+        }
+        owned.forEach { cellsOfRegion ->
+            assertTrue("an empty colour", cellsOfRegion.isNotEmpty())
+            val cats = cellsOfRegion.count { (r, c) -> puzzle.catCols[r] == c }
+            assertEquals("a colour with ${cats}cats", 1, cats)
+
+            // Contiguous: a breadth-first walk from the first cell reaches all.
+            val rest = cellsOfRegion.toMutableSet()
+            val queue = ArrayDeque(listOf(rest.first()))
+            val reached = mutableSetOf(queue.first())
+            while (queue.isNotEmpty()) {
+                val (r, c) = queue.removeFirst()
+                for ((dr, dc) in listOf(0 to 1, 0 to -1, 1 to 0, -1 to 0)) {
+                    val next = (r + dr) to (c + dc)
+                    if (next in rest && reached.add(next)) queue.add(next)
+                }
+            }
+            assertEquals("a colour in two pieces", rest.size, reached.size)
+        }
+    }
+
+    @Test
+    fun `the cats can always be settled`() {
+        // A four board is the smallest deal, and its answer is the point where
+        // no-touch and one-per-line first stop contradicting each other.
+        val rng = SeededRng(42)
+        val cols = MeowdokuGenerator.placeCats(4, rng)
+        assertEquals(4, cols.size)
+        // The placement the generator returns is internally consistent.
+        for (row in 0 until 4) {
+            for (earlier in 0 until row) {
+                assertFalse(MeowdokuGenerator.catFitsHere(row, cols[earlier], cols))
+            }
+        }
+    }
+
+    // ---- the referee -------------------------------------------------------
+
+    @Test
+    fun `the board opens empty and seated for one`() {
+        val state = dealt(6)
+        assertTrue(state.cats.isEmpty())
+        assertTrue(state.marks.isEmpty())
+        assertEquals(6, state.side)
+        assertEquals(3, state.heartsLeft)
+        assertEquals(0, state.catsFound)
+        assertEquals(0, MeowdokuRules.currentSeat(state))
+        assertFalse(MeowdokuRules.isFinished(state))
+        assertTrue(MeowdokuRules.legalMoves(state, 1).isEmpty())
+    }
+
+    @Test
+    fun `a correct tap lands a cat and a wrong tap costs a heart`() {
+        val state = dealt(6)
+        val square = Square(0, state.catCols[0])
+        val found = MeowdokuRules.applyMove(state, 0, PlaceCat(square))
+        assertTrue(square in found.cats)
+        assertEquals(3, found.heartsLeft)
+
+        val wrongRow = (0 until state.side).first { it != square.row }
+        val wrong = Square(wrongRow, if (state.catCols[wrongRow] == 0) 1 else 0)
+        val missed = MeowdokuRules.applyMove(found, 0, PlaceCat(wrong))
+        assertTrue(wrong in missed.marks)
+        assertFalse(wrong in missed.cats)
+        assertEquals(2, missed.heartsLeft)
+        assertEquals(1, missed.wrongCats)
+    }
+
+    @Test
+    fun `a board is solved by finding every cat`() {
+        var state = dealt(5)
+        for (row in 0 until 5) {
+            state = MeowdokuRules.applyMove(state, 0, PlaceCat(Square(row, state.catCols[row])))
+        }
+        assertTrue(state.solved)
+        assertTrue(MeowdokuRules.isFinished(state))
+        assertNull(MeowdokuRules.currentSeat(state))
+        assertTrue(MeowdokuRules.legalMoves(state, 0).isEmpty())
+        assertTrue(MeowdokuRules.summary(state).startsWith("Solved"))
+    }
+
+    @Test
+    fun `running out of hearts loses the board`() {
+        val state = dealt(8, seed = 3L)
+        var lost = state
+        var row = 0
+        while (lost.heartsLeft > 0) {
+            // A wrong square: not the answer's column, in a row with no cat.
+            val wrongCol = if (state.catCols[row] == 0) 1 else 0
+            val before = lost.catsFound
+            lost = MeowdokuRules.applyMove(lost, 0, PlaceCat(Square(row, wrongCol)))
+            assertEquals(before, lost.catsFound)
+            row = (row + 1) % state.side
+        }
+        assertTrue(lost.lost)
+        assertTrue(MeowdokuRules.isFinished(lost))
+        assertEquals(0, lost.catsFound)
+        assertTrue(MeowdokuRules.summary(lost).startsWith("Lost"))
+    }
+
+    @Test
+    fun `a crossed square still takes a cat attempt`() {
+        // The double tap is one gesture pair: the first tap crosses the square
+        // and the second asks it. The cross the pair drew cannot veto the
+        // question that follows it.
+        val state = dealt(6)
+        val truth = Square(0, state.catCols[0])
+        val crossed = MeowdokuRules.applyMove(state, 0, TogglePencil(truth))
+        assertTrue(truth in crossed.marks)
+        assertTrue(
+            "the attempt is offered over its own cross",
+            PlaceCat(truth) in MeowdokuRules.legalMoves(crossed, 0),
+        )
+
+        val placed = MeowdokuRules.applyMove(crossed, 0, PlaceCat(truth))
+        assertTrue(truth in placed.cats)
+        assertFalse("the cat replaces the cross", truth in placed.marks)
+        assertEquals(3, placed.heartsLeft)
+        assertEquals(0, placed.wrongCats)
+    }
+
+    @Test
+    fun `a wrong pair keeps its cross and spends a heart`() {
+        val state = dealt(6)
+        val wrongCol = if (state.catCols[1] == 0) 1 else 0
+        val wrong = Square(1, wrongCol)
+        val crossed = MeowdokuRules.applyMove(state, 0, TogglePencil(wrong))
+        val judged = MeowdokuRules.applyMove(crossed, 0, PlaceCat(wrong))
+        assertTrue(wrong in judged.marks)
+        assertFalse(wrong in judged.cats)
+        assertEquals(2, judged.heartsLeft)
+        assertEquals(1, judged.wrongCats)
+    }
+
+    @Test
+    fun `pencil marks are free notes`() {
+        val state = dealt(6)
+        val square = Square(2, if (state.catCols[2] == 5) 4 else 5)
+        val marked = MeowdokuRules.applyMove(state, 0, TogglePencil(square))
+        assertTrue(square in marked.marks)
+        assertEquals(3, marked.heartsLeft)
+        assertEquals(0, marked.wrongCats)
+
+        val erased = MeowdokuRules.applyMove(marked, 0, TogglePencil(square))
+        assertTrue(erased.marks.isEmpty())
+    }
+
+    @Test
+    fun `a cat square is never a pencil square`() {
+        val state = dealt(6)
+        val cat = Square(0, state.catCols[0])
+        val found = MeowdokuRules.applyMove(state, 0, PlaceCat(cat))
+        assertFalse(
+            "legal moves offer pencil on a cat",
+            MeowdokuRules.legalMoves(found, 0).any {
+                it is TogglePencil && it.square == cat
+            },
+        )
+    }
+
+    @Test
+    fun `a hint shows a missing cat and costs one token`() {
+        val state = dealt(6)
+        val hinted = MeowdokuRules.applyMove(state, 0, TakeHint)
+        assertEquals(1, hinted.catsFound)
+        assertEquals(2, hinted.hintsLeft)
+
+        // Out of hints the move stops being offered.
+        var drained = MeowdokuRules.applyMove(
+            MeowdokuRules.applyMove(hinted, 0, TakeHint),
+            0,
+            TakeHint,
+        )
+        assertEquals(0, drained.hintsLeft)
+        // A note on a square that is not a cat, so the pencil move is legal.
+        val note = Square(0, if (state.catCols[0] == 0) 1 else 0)
+        drained = MeowdokuRules.applyMove(drained, 0, TogglePencil(note))
+        assertFalse(TakeHint in MeowdokuRules.legalMoves(drained, 0))
+    }
+
+    @Test
+    fun `a hint over a wrong pencil reveals the cat anyway`() {
+        val state = dealt(6)
+        val truth = Square(0, state.catCols[0])
+        val pencilled = MeowdokuRules.applyMove(state, 0, TogglePencil(truth))
+        val revealed = MeowdokuRules.applyMove(pencilled, 0, TakeHint)
+        assertTrue(truth in revealed.cats)
+        assertFalse(truth in revealed.marks)
+    }
+
+    @Test
+    fun `the computer can finish any board it is handed`() {
+        var state = dealt(7)
+        var guard = 0
+        while (!MeowdokuRules.isFinished(state) && guard++ < 100) {
+            val legal = MeowdokuRules.legalMoves(state, 0)
+            assertFalse("stuck with cats still missing", legal.isEmpty())
+            state = MeowdokuRules.applyMove(state, 0, MeowdokuAi.chooseMove(state, 0, legal))
+        }
+        assertTrue("the AI did not solve the board", state.solved)
+    }
+
+    // ---- state across the wire and the save slot ---------------------------
+
+    @Test
+    fun `state and moves survive their json`() {
+        val state = dealt(6)
+        val decoded = MeowdokuRules.decodeState(MeowdokuRules.encodeState(state))
+        assertEquals(state, decoded)
+
+        val move: MeowdokuMove = PlaceCat(Square(1, 1))
+        assertEquals(move, MeowdokuRules.decodeMove(MeowdokuRules.encodeMove(move)))
+        assertEquals(TakeHint, MeowdokuRules.decodeMove(MeowdokuRules.encodeMove(TakeHint)))
+    }
+
+    @Test
+    fun `nothing is hidden from the only seat`() {
+        val state = dealt(6)
+        assertEquals(state, MeowdokuRules.viewFor(state, 0))
+    }
+
+    @Test
+    fun `a table with two seats is refused`() {
+        val config = TableConfig(
+            gameId = "meowdoku",
+            seats = listOf(
+                PlayerSlot(0, "P0", PlayerKind.HUMAN_LOCAL, 0),
+                PlayerSlot(1, "P1", PlayerKind.AI, 1),
+            ),
+            optionsJson = json.encodeToString(MeowdokuOptions()),
+            seed = 1L,
+        )
+        assertThrows(IllegalArgumentException::class.java) {
+            MeowdokuRules.initialState(config)
+        }
+    }
+
+    @Test
+    fun `the options guard their own board`() {
+        assertThrows(IllegalArgumentException::class.java) { MeowdokuOptions(side = 3) }
+        assertThrows(IllegalArgumentException::class.java) { MeowdokuOptions(side = 11) }
+        assertThrows(IllegalArgumentException::class.java) { MeowdokuOptions(hearts = 0) }
+    }
+}

app/src/test/java/org/prolibertate/games/game/yahtzee/YahtzeeStatsTest.kt

@@ -0,0 +1,30 @@
+package org.prolibertate.games.game.yahtzee
+
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertNull
+import org.junit.Test
+
+class YahtzeeStatsTest {
+    private fun game(total: Int, bonus: Boolean = false, yahtzees: Int = 0, won: Boolean = true) =
+        YahtzeeRecord(total, bonus, yahtzees, zeros = 0, players = 2, won = won)
+
+    @Test
+    fun firstGameHasNothingToCompareTo() {
+        val c = compareToHistory(emptyList(), game(200))
+        assertEquals(1, c.rank)
+        assertEquals(0, c.previousGames)
+        assertNull(c.bestBefore)
+        assertNull(c.averageBefore)
+    }
+
+    @Test
+    fun ranksAgainstPreviousGames() {
+        val history = listOf(game(150, bonus = true, yahtzees = 1), game(250), game(200, won = false))
+        val c = compareToHistory(history, game(220))
+        assertEquals(2, c.rank)
+        assertEquals(4, c.gamesRanked)
+        assertEquals(250, c.bestBefore)
+        assertEquals(200.0, c.averageBefore!!, 0.001)
+        assertEquals(1, c.yahtzeesBefore)
+    }
+}

app/src/test/java/org/prolibertate/games/net/MatchSaverTest.kt

@@ -0,0 +1,191 @@
+package org.prolibertate.games.net
+
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.Job
+import kotlinx.coroutines.cancel
+import kotlinx.coroutines.delay
+import kotlinx.coroutines.runBlocking
+import org.junit.After
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertFalse
+import org.junit.Assert.assertNotNull
+import org.junit.Assert.assertNull
+import org.junit.Assert.assertTrue
+import org.junit.Rule
+import org.junit.Test
+import org.junit.rules.TemporaryFolder
+import org.prolibertate.games.game.engine.GameAi
+import org.prolibertate.games.game.engine.GameRules
+import org.prolibertate.games.game.engine.PlayerKind
+import org.prolibertate.games.game.engine.PlayerSlot
+import org.prolibertate.games.game.engine.SavedGameStore
+import org.prolibertate.games.game.engine.TableConfig
+import java.io.File
+
+/**
+ * Saving a table as it is played, and starting a table from a save.
+ *
+ * The game here is a counter: one seat, a move adds one, and it is finished at
+ * [GOAL]. It has hidden state — [Counter.secret] — so the tests can check that
+ * what is saved is the true state, not the view a player is shown.
+ */
+class MatchSaverTest {
+
+    @get:Rule
+    val folder = TemporaryFolder()
+
+    private val scopes = mutableListOf<CoroutineScope>()
+
+    @After
+    fun tearDown() {
+        scopes.forEach { it.cancel() }
+    }
+
+    private data class Counter(val n: Int, val secret: String)
+
+    private object Rules : GameRules<Counter, String> {
+        override val gameId = "counter"
+        override fun initialState(config: TableConfig) = Counter(0, "hidden-${config.seed}")
+        override fun currentSeat(state: Counter): Int? = if (state.n >= GOAL) null else 0
+        override fun legalMoves(state: Counter, seat: Int) = if (state.n >= GOAL) emptyList() else listOf("add")
+        override fun applyMove(state: Counter, seat: Int, move: String) = state.copy(n = state.n + 1)
+        override fun isFinished(state: Counter) = state.n >= GOAL
+        override fun summary(state: Counter) = "at ${state.n}"
+        override fun viewFor(state: Counter, seat: Int) = state.copy(secret = "")
+        override fun encodeState(state: Counter) = "${state.n}|${state.secret}"
+        override fun decodeState(json: String): Counter {
+            val (n, secret) = json.split("|", limit = 2)
+            return Counter(n.toInt(), secret)
+        }
+
+        override fun encodeMove(move: String) = move
+        override fun decodeMove(json: String) = json
+    }
+
+    private val config = TableConfig(
+        gameId = "counter",
+        seats = listOf(PlayerSlot(0, "You", PlayerKind.HUMAN_LOCAL, 0)),
+        optionsJson = "{}",
+        seed = 7L,
+    )
+
+    private fun scope() = CoroutineScope(Job() + Dispatchers.Default).also { scopes += it }
+
+    private fun controller(): MatchController<Counter, String> = MatchController(
+        rules = Rules,
+        ai = object : GameAi<Counter, String> {
+            override fun chooseMove(state: Counter, seat: Int, legal: List<String>) = legal.first()
+        },
+        config = config,
+        scope = scope(),
+        role = MatchController.Role.HOST,
+        localSeats = setOf(0),
+        primarySeat = 0,
+    )
+
+    private fun store() = SavedGameStore(File(folder.root, "saves"))
+
+    private fun waitFor(what: String, check: () -> Boolean) = runBlocking {
+        repeat(200) {
+            if (check()) return@runBlocking
+            delay(10)
+        }
+        error("Timed out waiting for $what")
+    }
+
+    private fun saver(s: SavedGameStore, c: MatchController<Counter, String>) =
+        MatchSaver(s, "counter", config, localSeat = 0, scope = scope(), clock = { 123L }).also {
+            it.start()
+            c.onHostState = it::offer
+        }
+
+    @Test
+    fun `every position the table reaches is kept, with the true state`() {
+        val s = store()
+        val c = controller()
+        saver(s, c)
+        c.startAsHost(emptyList())
+        waitFor("the deal") { c.state.value != null }
+        c.submit("add")
+        c.submit("add")
+        waitFor("two moves") { s.load("counter")?.stateJson?.startsWith("2|") == true }
+
+        val saved = s.load("counter")!!
+        assertEquals("2|hidden-7", saved.stateJson) // the hidden part is saved; the view blanks it
+        assertEquals("at 2", saved.summary)
+        assertEquals(123L, saved.savedAtMillis)
+        assertEquals(config, saved.config)
+    }
+
+    @Test
+    fun `a table started from a save carries on from where it stood`() {
+        val s = store()
+        val first = controller()
+        saver(s, first)
+        first.startAsHost(emptyList())
+        waitFor("the deal") { first.state.value != null }
+        repeat(3) { first.submit("add") }
+        waitFor("three moves") { s.load("counter")?.stateJson?.startsWith("3|") == true }
+        first.close()
+
+        val second = controller()
+        assertTrue(second.restore(s.load("counter")!!.stateJson))
+        second.startAsHost(emptyList())
+        waitFor("the restored table") { second.state.value != null }
+        assertEquals(3, second.state.value!!.n)
+        second.submit("add")
+        waitFor("a move after resuming") { second.state.value!!.n == 4 }
+    }
+
+    @Test
+    fun `a save the game cannot read is refused and the table is dealt afresh`() {
+        val c = controller()
+        assertFalse(c.restore("not a counter"))
+        c.startAsHost(emptyList())
+        waitFor("a fresh deal") { c.state.value != null }
+        assertEquals(0, c.state.value!!.n)
+    }
+
+    @Test
+    fun `a finished game is not kept`() {
+        val s = store()
+        val c = controller()
+        saver(s, c)
+        c.startAsHost(emptyList())
+        waitFor("the deal") { s.load("counter") != null }
+        repeat(GOAL) { c.submit("add") }
+        waitFor("the finish") { c.finished.value }
+        waitFor("the slot to clear") { s.load("counter") == null }
+    }
+
+    @Test
+    fun `flush writes the position the background writer has not reached`() {
+        val s = store()
+        val saver = MatchSaver(s, "counter", config, 0, scope(), clock = { 1L })
+        // Not started: nothing is written in the background at all.
+        saver.offer(MatchController.HostSnapshot(false, "at 5") { "5|x" })
+        assertNull(s.load("counter"))
+        saver.flush()
+        assertEquals("5|x", s.load("counter")!!.stateJson)
+    }
+
+    @Test
+    fun `ending a game on purpose forgets it and writes no more`() {
+        val s = store()
+        val saver = MatchSaver(s, "counter", config, 0, scope(), clock = { 1L })
+        saver.offer(MatchController.HostSnapshot(false, "at 1") { "1|x" })
+        saver.flush()
+        assertNotNull(s.load("counter"))
+        saver.discard()
+        assertNull(s.load("counter"))
+        // Leaving after ending must not put it back.
+        saver.offer(MatchController.HostSnapshot(false, "at 2") { "2|x" })
+        saver.flush()
+        assertNull(s.load("counter"))
+    }
+
+    private companion object {
+        const val GOAL = 5
+    }
+}

app/src/test/java/org/prolibertate/games/net/SaveRoundTripAllGamesTest.kt

@@ -0,0 +1,177 @@
+package org.prolibertate.games.net
+
+import kotlinx.serialization.encodeToString
+import kotlinx.serialization.json.Json
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertTrue
+import org.junit.Test
+import org.prolibertate.games.game.GameCatalog
+import org.prolibertate.games.game.engine.GameAi
+import org.prolibertate.games.game.engine.GameRules
+import org.prolibertate.games.game.engine.PlayerKind
+import org.prolibertate.games.game.engine.PlayerSlot
+import org.prolibertate.games.game.engine.TableConfig
+import org.prolibertate.games.ui.seatCountFor
+import org.prolibertate.games.game.backgammon.BackgammonAi
+import org.prolibertate.games.game.backgammon.BackgammonOptions
+import org.prolibertate.games.game.backgammon.BackgammonRules
+import org.prolibertate.games.game.catan.CatanAi
+import org.prolibertate.games.game.catan.CatanOptions
+import org.prolibertate.games.game.catan.CatanRules
+import org.prolibertate.games.game.checkers.CheckersAi
+import org.prolibertate.games.game.checkers.CheckersOptions
+import org.prolibertate.games.game.checkers.CheckersRules
+import org.prolibertate.games.game.chess.ChessAi
+import org.prolibertate.games.game.chess.ChessOptions
+import org.prolibertate.games.game.chess.ChessRules
+import org.prolibertate.games.game.crazyeights.CrazyEightsAi
+import org.prolibertate.games.game.crazyeights.CrazyEightsOptions
+import org.prolibertate.games.game.crazyeights.CrazyEightsRules
+import org.prolibertate.games.game.cribbage.CribbageAi
+import org.prolibertate.games.game.cribbage.CribbageOptions
+import org.prolibertate.games.game.cribbage.CribbageRules
+import org.prolibertate.games.game.euchre.EuchreAi
+import org.prolibertate.games.game.euchre.EuchreOptions
+import org.prolibertate.games.game.euchre.EuchreRules
+import org.prolibertate.games.game.freecell.FreeCellOptions
+import org.prolibertate.games.game.freecell.FreeCellRules
+import org.prolibertate.games.game.golf.GolfAi
+import org.prolibertate.games.game.golf.GolfOptions
+import org.prolibertate.games.game.golf.GolfRules
+import org.prolibertate.games.game.hearts.HeartsAi
+import org.prolibertate.games.game.hearts.HeartsOptions
+import org.prolibertate.games.game.hearts.HeartsRules
+import org.prolibertate.games.game.kaiser.KaiserAi
+import org.prolibertate.games.game.kaiser.KaiserOptions
+import org.prolibertate.games.game.kaiser.KaiserRules
+import org.prolibertate.games.game.klondike.KlondikeAi
+import org.prolibertate.games.game.klondike.KlondikeOptions
+import org.prolibertate.games.game.klondike.KlondikeRules
+import org.prolibertate.games.game.mastermind.MastermindAi
+import org.prolibertate.games.game.mastermind.MastermindOptions
+import org.prolibertate.games.game.mastermind.MastermindRules
+import org.prolibertate.games.game.morris.MorrisAi
+import org.prolibertate.games.game.morris.MorrisOptions
+import org.prolibertate.games.game.morris.MorrisRules
+import org.prolibertate.games.game.pegsolitaire.PegSolitaireAi
+import org.prolibertate.games.game.pegsolitaire.PegSolitaireOptions
+import org.prolibertate.games.game.pegsolitaire.PegSolitaireRules
+import org.prolibertate.games.game.pirates.PiratesAi
+import org.prolibertate.games.game.pirates.PiratesOptions
+import org.prolibertate.games.game.pirates.PiratesRules
+import org.prolibertate.games.game.president.PresidentAi
+import org.prolibertate.games.game.president.PresidentOptions
+import org.prolibertate.games.game.president.PresidentRules
+import org.prolibertate.games.game.pyramid.PyramidOptions
+import org.prolibertate.games.game.pyramid.PyramidRules
+import org.prolibertate.games.game.sequence.SequenceAi
+import org.prolibertate.games.game.sequence.SequenceOptions
+import org.prolibertate.games.game.sequence.SequenceRules
+import org.prolibertate.games.game.solitaire.FirstLegalAi
+import org.prolibertate.games.game.spider.SpiderOptions
+import org.prolibertate.games.game.spider.SpiderRules
+import org.prolibertate.games.game.tayu.TayuAi
+import org.prolibertate.games.game.tayu.TayuOptions
+import org.prolibertate.games.game.tayu.TayuRules
+import org.prolibertate.games.game.wizard.WizardAi
+import org.prolibertate.games.game.wizard.WizardOptions
+import org.prolibertate.games.game.wizard.WizardRules
+import org.prolibertate.games.game.yahtzee.YahtzeeAi
+import org.prolibertate.games.game.yahtzee.YahtzeeOptions
+import org.prolibertate.games.game.yahtzee.YahtzeeRules
+
+/**
+ * Every game can be saved and picked up again.
+ *
+ * For each game in the catalogue a table is dealt and played by the computer, and
+ * at every single move the whole true state is encoded and decoded again — which
+ * is exactly what saving it to disk and resuming does — and play carries on from
+ * the decoded copy. A game whose state does not survive that, or that cannot make
+ * a legal move from a state it has been through it, fails here.
+ */
+class SaveRoundTripAllGamesTest {
+
+    private val json = Json { encodeDefaults = true }
+
+    private fun <S : Any, M : Any> exercise(
+        gameId: String,
+        rules: GameRules<S, M>,
+        ai: GameAi<S, M>,
+        optionsJson: String,
+        steps: Int = 120,
+    ) {
+        val seats = seatCountFor(gameId, optionsJson)
+        val config = TableConfig(
+            gameId = gameId,
+            seats = (0 until seats).map {
+                PlayerSlot(it, "P$it", if (it == 0) PlayerKind.HUMAN_LOCAL else PlayerKind.AI, it)
+            },
+            optionsJson = optionsJson,
+            seed = 20240607L,
+        )
+        var state = rules.initialState(config)
+        var moves = 0
+        repeat(steps) {
+            if (rules.isFinished(state)) return
+            // The save and the resume: what goes to disk, and what comes back.
+            val saved = rules.encodeState(state)
+            val back = rules.decodeState(saved)
+            assertEquals("$gameId: a saved state encodes differently after a resume", saved, rules.encodeState(back))
+            assertEquals(
+                "$gameId: a resumed state is not on the same seat's turn",
+                rules.currentSeat(state),
+                rules.currentSeat(back),
+            )
+            assertEquals(
+                "$gameId: a resumed state has different legal moves",
+                rules.currentSeat(state)?.let { rules.legalMoves(state, it) },
+                rules.currentSeat(back)?.let { rules.legalMoves(back, it) },
+            )
+            state = back
+
+            val seat = rules.currentSeat(state) ?: return // waiting on a scoreboard, which is not a move
+            val legal = rules.legalMoves(state, seat)
+            if (legal.isEmpty()) return
+            val move = ai.chooseMove(state, seat, legal)
+            assertTrue("$gameId: move $move is not legal after a resume", rules.isLegalMove(state, seat, move))
+            state = rules.applyMove(state, seat, move)
+            moves++
+        }
+        assertTrue("$gameId: made no moves", moves > 0)
+    }
+
+    private inline fun <reified O> opts(o: O) = json.encodeToString(o)
+
+    @Test fun euchre() = exercise(GameCatalog.EUCHRE, EuchreRules, EuchreAi(), opts(EuchreOptions()))
+    @Test fun sequence() = exercise(GameCatalog.SEQUENCE, SequenceRules, SequenceAi(), opts(SequenceOptions()))
+    @Test fun president() = exercise(GameCatalog.PRESIDENT, PresidentRules, PresidentAi(), opts(PresidentOptions()))
+    @Test fun golf() = exercise(GameCatalog.GOLF, GolfRules, GolfAi(), opts(GolfOptions()))
+    @Test fun kaiser() = exercise(GameCatalog.KAISER, KaiserRules, KaiserAi(), opts(KaiserOptions()))
+    @Test fun wizard() = exercise(GameCatalog.WIZARD, WizardRules, WizardAi(), opts(WizardOptions()))
+    @Test fun crazyEights() = exercise(GameCatalog.CRAZY_EIGHTS, CrazyEightsRules, CrazyEightsAi(), opts(CrazyEightsOptions()))
+    @Test fun cribbage() = exercise(GameCatalog.CRIBBAGE, CribbageRules, CribbageAi(), opts(CribbageOptions()))
+    @Test fun tayu() = exercise(GameCatalog.TAYU, TayuRules, TayuAi(), opts(TayuOptions()))
+    @Test fun checkers() = exercise(GameCatalog.CHECKERS, CheckersRules, CheckersAi(), opts(CheckersOptions()))
+    @Test fun backgammon() = exercise(GameCatalog.BACKGAMMON, BackgammonRules, BackgammonAi(), opts(BackgammonOptions()))
+    @Test fun mastermind() = exercise(GameCatalog.MASTERMIND, MastermindRules, MastermindAi(), opts(MastermindOptions()))
+    @Test fun pirates() = exercise(GameCatalog.PIRATES, PiratesRules, PiratesAi(), opts(PiratesOptions()))
+    @Test fun hearts() = exercise(GameCatalog.HEARTS, HeartsRules, HeartsAi, opts(HeartsOptions()))
+    @Test fun pegSolitaire() = exercise(GameCatalog.PEG_SOLITAIRE, PegSolitaireRules, PegSolitaireAi, opts(PegSolitaireOptions()))
+    @Test fun yahtzee() = exercise(GameCatalog.YAHTZEE, YahtzeeRules, YahtzeeAi, opts(YahtzeeOptions()))
+    @Test fun klondike() = exercise(GameCatalog.KLONDIKE, KlondikeRules, KlondikeAi, opts(KlondikeOptions()))
+    @Test fun freecell() = exercise(GameCatalog.FREECELL, FreeCellRules, FirstLegalAi(), opts(FreeCellOptions()))
+    @Test fun spider() = exercise(GameCatalog.SPIDER, SpiderRules, FirstLegalAi(), opts(SpiderOptions()))
+    @Test fun pyramid() = exercise(GameCatalog.PYRAMID, PyramidRules, FirstLegalAi(), opts(PyramidOptions()))
+    @Test fun morris() = exercise(GameCatalog.MORRIS, MorrisRules, MorrisAi(), opts(MorrisOptions()))
+    @Test fun chess() = exercise(GameCatalog.CHESS, ChessRules, ChessAi(), opts(ChessOptions()), steps = 24)
+    @Test fun catan() = exercise(GameCatalog.CATAN, CatanRules, CatanAi(), opts(CatanOptions()), steps = 400)
+
+    @Test
+    fun catanCitiesAndKnights() = exercise(
+        GameCatalog.CATAN,
+        CatanRules,
+        CatanAi(),
+        opts(CatanOptions(3, 13, org.prolibertate.games.game.catan.CatanRuleSet.CITIES_AND_KNIGHTS)),
+        steps = 600,
+    )
+}

app/src/test/java/org/prolibertate/games/net/ScorekeeperSessionTest.kt

@@ -145,6 +145,11 @@ class ScorekeeperSessionTest {
         await("$name to be asking") { host.state.requests.any { it.id == deviceId } }
         host.session.allow(deviceId)
         await("$name to be let in") { guest.state.value.connected }
+        // The sheet follows the connection over the socket, so `connected` can
+        // flip while it is still in flight. Callers read the guest's sheet at
+        // once (its players, its rounds), and on a slow runner that was an empty
+        // one: wait until the guest is looking at the host's.
+        await("$name to receive the sheet") { guest.state.value.sheet == host.state.sheet }
         return guest
     }
 

app/src/test/java/org/prolibertate/games/score/RecentNamesTest.kt

@@ -0,0 +1,30 @@
+package org.prolibertate.games.score
+
+import org.junit.Test
+import org.junit.Assert.assertEquals
+
+class RecentNamesTest {
+    @Test
+    fun newestComesFirst() {
+        assertEquals(listOf("Bo", "Al"), RecentNames.with(listOf("Al"), "Bo"))
+    }
+
+    @Test
+    fun repeatMovesToFrontIgnoringCase() {
+        assertEquals(listOf("al", "Bo"), RecentNames.with(listOf("Bo", "Al"), " al "))
+    }
+
+    @Test
+    fun blankChangesNothing() {
+        assertEquals(listOf("Al"), RecentNames.with(listOf("Al"), "   "))
+    }
+
+    @Test
+    fun keepsOnlyTen() {
+        val names = (1..10).map { "n$it" }
+        val result = RecentNames.with(names, "new")
+        assertEquals(10, result.size)
+        assertEquals("new", result.first())
+        assertEquals("n9", result.last())
+    }
+}

app/src/test/java/org/prolibertate/games/score/ScoreSheetTest.kt

@@ -199,6 +199,14 @@ class ScoreSheetTest {
         assertEquals(ScoringMode.ROUNDS, StartSheet(3).applyTo(ScoreSheet()).mode)
     }
 
+    @Test
+    fun startingWithNamesSeatsThemInOrderAndLeavesTheRestUnnamed() {
+        val sheet = StartSheet(3, names = listOf("Ann", "")).applyTo(ScoreSheet())
+        assertEquals(listOf("Ann", "", ""), sheet.players.map { it.name })
+        assertEquals("Ann", sheet.displayName(sheet.players[0]))
+        assertEquals("Player 2", sheet.displayName(sheet.players[1]))
+    }
+
     @Test
     fun `tally entries add up per player and can be taken back`() {
         val sheet = ScoreSheet.of(2, ScoringMode.TALLY)

app/src/test/java/org/prolibertate/games/ui/SavedGameTextTest.kt

@@ -0,0 +1,27 @@
+package org.prolibertate.games.ui
+
+import org.junit.Assert.assertEquals
+import org.junit.Test
+
+class SavedGameTextTest {
+    private val minute = 60_000L
+    private val hour = 60 * minute
+    private val day = 24 * hour
+
+    @Test
+    fun `how long ago reads like a person would say it`() {
+        assertEquals("just now", agoText(1_000, 1_000))
+        assertEquals("just now", agoText(30_000, 0))
+        assertEquals("a minute ago", agoText(minute + 20_000, 0))
+        assertEquals("5 minutes ago", agoText(5 * minute, 0))
+        assertEquals("an hour ago", agoText(90 * minute, 0))
+        assertEquals("3 hours ago", agoText(3 * hour, 0))
+        assertEquals("yesterday", agoText(30 * hour, 0))
+        assertEquals("4 days ago", agoText(4 * day, 0))
+    }
+
+    @Test
+    fun `a clock that ran backwards does not say nonsense`() {
+        assertEquals("just now", agoText(0, 10 * minute))
+    }
+}

app/src/test/java/org/prolibertate/games/ui/game/catan/CatanCkInteractionTest.kt

@@ -0,0 +1,291 @@
+package org.prolibertate.games.ui.game.catan
+
+import kotlinx.serialization.encodeToString
+import kotlinx.serialization.json.Json
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertTrue
+import org.junit.Test
+import org.prolibertate.games.game.GameCatalog
+import org.prolibertate.games.game.catan.AcceptCounter
+import org.prolibertate.games.game.catan.AcceptTrade
+import org.prolibertate.games.game.catan.CounterGoods
+import org.prolibertate.games.game.catan.DismissCounters
+import org.prolibertate.games.game.catan.ActivateKnight
+import org.prolibertate.games.game.catan.BuildCity
+import org.prolibertate.games.game.catan.BuildRoad
+import org.prolibertate.games.game.catan.BuildSettlement
+import org.prolibertate.games.game.catan.BuildWall
+import org.prolibertate.games.game.catan.BuyImprovement
+import org.prolibertate.games.game.catan.CatanAi
+import org.prolibertate.games.game.catan.CatanBoard
+import org.prolibertate.games.game.catan.CatanMove
+import org.prolibertate.games.game.catan.CatanOptions
+import org.prolibertate.games.game.catan.CatanPhase
+import org.prolibertate.games.game.catan.CatanRuleSet
+import org.prolibertate.games.game.catan.CatanRules
+import org.prolibertate.games.game.catan.CatanState
+import org.prolibertate.games.game.catan.ChaseRobber
+import org.prolibertate.games.game.catan.DeclineTrade
+import org.prolibertate.games.game.catan.DiscardGoods
+import org.prolibertate.games.game.catan.DropProgress
+import org.prolibertate.games.game.catan.EndFreeRoads
+import org.prolibertate.games.game.catan.EndSmith
+import org.prolibertate.games.game.catan.EndTurn
+import org.prolibertate.games.game.catan.GiveGoods
+import org.prolibertate.games.game.catan.GoodsBankTrade
+import org.prolibertate.games.game.catan.HireKnight
+import org.prolibertate.games.game.catan.MoveKnight
+import org.prolibertate.games.game.catan.MoveRobber
+import org.prolibertate.games.game.catan.OfferGoods
+import org.prolibertate.games.game.catan.PickDeck
+import org.prolibertate.games.game.catan.PillageCity
+import org.prolibertate.games.game.catan.PlaceKnight
+import org.prolibertate.games.game.catan.PlaceMetropolis
+import org.prolibertate.games.game.catan.PlayProgress
+import org.prolibertate.games.game.catan.PromoteKnight
+import org.prolibertate.games.game.catan.RelocateKnight
+import org.prolibertate.games.game.catan.RemoveKnight
+import org.prolibertate.games.game.catan.RollDice
+import org.prolibertate.games.game.catan.SetupPlace
+import org.prolibertate.games.game.catan.SpyTake
+import org.prolibertate.games.game.catan.TakeAqueduct
+import org.prolibertate.games.game.engine.PlayerKind
+import org.prolibertate.games.game.engine.PlayerSlot
+import org.prolibertate.games.game.engine.TableConfig
+
+/**
+ * Cities & Knights has no device in this test suite, so the screen's logic is
+ * checked another way: engines play whole games, and at every position the
+ * player on the clock is treated as the local one. For every move the engine says
+ * is legal, [CatanInteraction] (and the dialogs' own filters) must offer a way to
+ * make it — a tap, a button or a dialog choice. A legal move that no control can
+ * produce would be a stuck game on a real phone.
+ */
+class CatanCkInteractionTest {
+
+    private val json = Json { encodeDefaults = true }
+
+    private fun config(players: Int, seed: Long) = TableConfig(
+        gameId = GameCatalog.CATAN,
+        seats = (0 until players).map { PlayerSlot(seat = it, name = "P$it", kind = PlayerKind.AI, team = it) },
+        optionsJson = json.encodeToString(
+            CatanOptions(players, pointsToWin = 13, ruleSet = CatanRuleSet.CITIES_AND_KNIGHTS),
+        ),
+        seed = seed,
+    )
+
+    /** How a move reaches the engine from the screen, or null if nothing can produce it. */
+    private fun reachable(state: CatanState, legal: List<CatanMove>, move: CatanMove): String? {
+        fun tapVertex(vertex: Int, building: BuildKind? = null, moving: Int? = null, armed: ArmedCard? = null): TapOutcome =
+            CatanInteraction.onVertexTap(vertex, legal, building, null, moving, armed)
+
+        return when (move) {
+            is SetupPlace -> {
+                val vertex = CatanInteraction.targets(state, legal, null, null).vertices
+                val edges = CatanInteraction.targets(state, legal, null, move.vertex).edges
+                "setup".takeIf {
+                    move.vertex in vertex && move.edge in edges &&
+                        CatanInteraction.onVertexTap(move.vertex, legal, null, null) is TapOutcome.PickSetupVertex &&
+                        CatanInteraction.onEdgeTap(move.edge, legal, null, move.vertex) == TapOutcome.Submit(move)
+                }
+            }
+
+            is BuildRoad -> {
+                val targets = CatanInteraction.targets(state, legal, BuildKind.ROAD, null)
+                "road".takeIf {
+                    move.edge in targets.edges &&
+                        CatanInteraction.onEdgeTap(move.edge, legal, BuildKind.ROAD, null) == TapOutcome.Submit(move)
+                }
+            }
+
+            is BuildSettlement -> viaBuild(state, legal, BuildKind.SETTLEMENT, move.vertex, move)
+            is BuildCity -> viaBuild(state, legal, BuildKind.CITY, move.vertex, move)
+            is BuildWall -> viaBuild(state, legal, BuildKind.WALL, move.vertex, move)
+            is HireKnight -> viaBuild(state, legal, BuildKind.KNIGHT, move.vertex, move)
+
+            is MoveRobber -> {
+                val hex = CatanBoard.hexIndex.getValue(move.hex)
+                val targets = CatanInteraction.targets(state, legal, null, null)
+                val tap = CatanInteraction.onHexTap(hex, legal)
+                "robber".takeIf {
+                    hex in targets.hexes &&
+                        (tap == TapOutcome.Submit(move) || (tap is TapOutcome.PickRobberVictim && move.victim in tap.victims))
+                }
+            }
+
+            is MoveKnight -> {
+                val targets = CatanInteraction.targets(state, legal, null, null, movingKnight = move.from)
+                "moveKnight".takeIf {
+                    move.to in targets.vertices && tapVertex(move.to, moving = move.from) == TapOutcome.Submit(move) &&
+                        move.from in CatanInteraction.targets(state, legal, null, null).knights &&
+                        CatanInteraction.knightActions(legal, move.from).any { it is MoveKnight }
+                }
+            }
+
+            is ActivateKnight, is ChaseRobber, is PromoteKnight -> {
+                val vertex = when (move) {
+                    is ActivateKnight -> move.vertex
+                    is ChaseRobber -> move.vertex
+                    else -> (move as PromoteKnight).vertex
+                }
+                val smith = legal.any { it is EndSmith }
+                if (move is PromoteKnight && smith) {
+                    val targets = CatanInteraction.targets(state, legal, null, null)
+                    "smith".takeIf {
+                        vertex in targets.vertices && tapVertex(vertex) == TapOutcome.Submit(move)
+                    }
+                } else {
+                    val targets = CatanInteraction.targets(state, legal, null, null)
+                    "knightMenu".takeIf {
+                        vertex in targets.knights && tapVertex(vertex) == TapOutcome.PickKnight(vertex) &&
+                            move in CatanInteraction.knightActions(legal, vertex)
+                    }
+                }
+            }
+
+            is PillageCity -> viaChore(state, legal, move.vertex, move)
+            is PlaceMetropolis -> viaChore(state, legal, move.vertex, move)
+            is RelocateKnight -> viaChore(state, legal, move.to, move)
+            is RemoveKnight -> viaChore(state, legal, move.vertex, move)
+            is PlaceKnight -> viaChore(state, legal, move.vertex, move)
+
+            is PlayProgress -> viaCard(state, legal, move)
+
+            is BuyImprovement -> "improve".takeIf { move.track in CatanInteraction.improvable(legal) }
+
+            is GoodsBankTrade ->
+                "bankTrade".takeIf { move.get in CatanInteraction.goodsBankTrades(legal)[move.give].orEmpty() }
+
+            RollDice(), is RollDice -> "roll".takeIf { CatanInteraction.canRoll(legal) }
+            EndTurn -> "endTurn".takeIf { CatanInteraction.canEndTurn(legal) }
+            EndFreeRoads -> "endRoads".takeIf { CatanInteraction.canEndFreeRoads(legal) }
+            EndSmith -> "endSmith".takeIf { CatanInteraction.canEndSmith(legal) }
+            AcceptTrade, DeclineTrade -> "tradeReply".takeIf { CatanInteraction.tradeResponses(legal) != (false to false) }
+
+            // Answered in a dialog that offers exactly the moves in the legal list.
+            is PickDeck, is DropProgress, is TakeAqueduct, is SpyTake -> "choreDialog"
+
+            // Structural: the discard and give dialogs build these and ask the engine.
+            is DiscardGoods, is GiveGoods -> "goodsDialog"
+            is OfferGoods, is CounterGoods -> "tradeDialog"
+            is AcceptCounter, DismissCounters -> "counterDialog"
+
+            else -> null
+        }
+    }
+
+    private fun viaBuild(state: CatanState, legal: List<CatanMove>, kind: BuildKind, vertex: Int, move: CatanMove): String? {
+        val targets = CatanInteraction.targets(state, legal, kind, null)
+        return "build $kind".takeIf {
+            vertex in targets.vertices &&
+                CatanInteraction.onVertexTap(vertex, legal, kind, null) == TapOutcome.Submit(move) &&
+                kind in CatanInteraction.canBuild(legal)
+        }
+    }
+
+    private fun viaChore(state: CatanState, legal: List<CatanMove>, vertex: Int, move: CatanMove): String? {
+        val targets = CatanInteraction.targets(state, legal, null, null)
+        return "chore".takeIf {
+            vertex in targets.vertices &&
+                CatanInteraction.onVertexTap(vertex, legal, null, null) == TapOutcome.Submit(move)
+        }
+    }
+
+    private fun viaCard(state: CatanState, legal: List<CatanMove>, move: PlayProgress): String? {
+        val seat = CatanRules.currentSeat(state) ?: return null
+        val entry = CatanInteraction.progressHand(state, seat, legal).firstOrNull { it.card.id == move.card }
+            ?: return null
+        val kind = entry.card.kind
+        if (move !in entry.plays) return null
+        if (kind !in CatanInteraction.BOARD_CARDS) return "cardDialog"
+
+        val armed = ArmedCard(kind, entry.plays)
+        val targets = CatanInteraction.targets(state, legal, null, null, armed = armed)
+        return when (kind) {
+            org.prolibertate.games.game.catan.ProgressType.DIPLOMAT ->
+                "armed".takeIf {
+                    move.edge in targets.edges &&
+                        CatanInteraction.onEdgeTap(move.edge!!, legal, null, null, armed) == TapOutcome.Submit(move)
+                }
+
+            org.prolibertate.games.game.catan.ProgressType.MERCHANT ->
+                "armed".takeIf {
+                    move.hexA in targets.hexes &&
+                        CatanInteraction.onHexTap(move.hexA!!, legal, armed) == TapOutcome.Submit(move)
+                }
+
+            org.prolibertate.games.game.catan.ProgressType.INVENTOR -> {
+                val first = CatanInteraction.onHexTap(move.hexA!!, legal, armed)
+                if (first != TapOutcome.PickFirstHex(move.hexA!!)) return null
+                val second = armed.copy(firstHex = move.hexA)
+                val partners = CatanInteraction.targets(state, legal, null, null, armed = second).hexes
+                "armed".takeIf {
+                    move.hexB in partners &&
+                        CatanInteraction.onHexTap(move.hexB!!, legal, second) == TapOutcome.Submit(move)
+                }
+            }
+
+            else ->
+                "armed".takeIf {
+                    move.vertex in targets.vertices &&
+                        CatanInteraction.onVertexTap(move.vertex!!, legal, null, null, null, armed) == TapOutcome.Submit(move)
+                }
+        }
+    }
+
+    private fun playAndCheck(players: Int, seed: Long): Map<String, Int> {
+        val ai = CatanAi()
+        var state = CatanRules.initialState(config(players, seed))
+        val seen = mutableMapOf<String, Int>()
+        var moves = 0
+        while (!CatanRules.isFinished(state) && moves++ < 20_000) {
+            val seat = CatanRules.currentSeat(state) ?: break
+            val legal = CatanRules.legalMoves(state, seat)
+            for (move in legal) {
+                val how = reachable(state, legal, move)
+                assertTrue(
+                    "seed $seed: no control produces $move in ${state.phase} " +
+                        "(chore ${state.ck?.chores?.firstOrNull()}); log tail: ${state.log.takeLast(3)}",
+                    how != null,
+                )
+                seen.merge(how!!, 1, Int::plus)
+            }
+            state = CatanRules.applyMove(state, seat, ai.chooseMove(state, seat, legal))
+        }
+        return seen
+    }
+
+    @Test
+    fun `every legal move in a full game has a control that produces it`() {
+        val total = mutableMapOf<String, Int>()
+        listOf(3 to 21L, 4 to 22L, 3 to 23L, 4 to 24L).forEach { (players, seed) ->
+            playAndCheck(players, seed).forEach { (k, v) -> total.merge(k, v, Int::plus) }
+        }
+        println("CK UI coverage: ${total.toSortedMap()}")
+        // The ways the screen builds, moves and answers all got exercised.
+        listOf("setup", "road", "build SETTLEMENT", "build CITY", "knightMenu", "improve", "bankTrade", "roll", "endTurn")
+            .forEach { assertTrue("never exercised: $it in $total", (total[it] ?: 0) > 0) }
+    }
+
+    @Test
+    fun `a sleeping knight with nothing to do can still be tapped for its menu`() {
+        val base = CatanRules.initialState(config(3, 5L))
+            .copy(phase = CatanPhase.PLAYING, turn = 0, turnNumber = 1)
+        val state = base.copy(
+            ck = base.ck!!.copy(knights = listOf(org.prolibertate.games.game.catan.Knight(10, 0, 1))),
+        )
+        val legal = CatanRules.legalMoves(state, 0)
+        assertTrue("no grain, so nothing to do", CatanInteraction.knightActions(legal, 10).isEmpty())
+
+        val targets = CatanInteraction.targets(state, legal, null, null, localSeat = 0)
+        assertTrue(10 in targets.idleKnights)
+        assertTrue("no tap ring for a knight with nothing to do", 10 !in targets.knights)
+        assertTrue(10 in targets.tappableVertices)
+        assertEquals(
+            TapOutcome.PickKnight(10),
+            CatanInteraction.onVertexTap(10, legal, null, null, ownKnights = setOf(10)),
+        )
+        // On somebody else's turn the legal list is empty and nothing is offered.
+        assertTrue(CatanInteraction.targets(state, emptyList(), null, null, localSeat = 0).idleKnights.isEmpty())
+    }
+}

app/src/test/java/org/prolibertate/games/ui/game/catan/CatanCkTextTest.kt

@@ -0,0 +1,75 @@
+package org.prolibertate.games.ui.game.catan
+
+import kotlinx.serialization.encodeToString
+import kotlinx.serialization.json.Json
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertTrue
+import org.junit.Test
+import org.prolibertate.games.game.GameCatalog
+import org.prolibertate.games.game.catan.CatanAi
+import org.prolibertate.games.game.catan.CatanOptions
+import org.prolibertate.games.game.catan.CatanRuleSet
+import org.prolibertate.games.game.catan.CatanRules
+import org.prolibertate.games.game.catan.ProgressType
+import org.prolibertate.games.game.engine.PlayerKind
+import org.prolibertate.games.game.engine.PlayerSlot
+import org.prolibertate.games.game.engine.TableConfig
+import org.prolibertate.games.ui.catanDefaultPoints
+import org.prolibertate.games.ui.catanPointsChoices
+import org.prolibertate.games.ui.catanSwitchRules
+
+class CatanCkTextTest {
+
+    private val json = Json { encodeDefaults = true }
+
+    @Test
+    fun `every position of a Cities and Knights game has a prompt for every seat`() {
+        val config = TableConfig(
+            gameId = GameCatalog.CATAN,
+            seats = (0 until 3).map { PlayerSlot(seat = it, name = "P$it", kind = PlayerKind.AI, team = it) },
+            optionsJson = json.encodeToString(
+                CatanOptions(3, 13, CatanRuleSet.CITIES_AND_KNIGHTS),
+            ),
+            seed = 31L,
+        )
+        var state = CatanRules.initialState(config)
+        val ai = CatanAi()
+        var moves = 0
+        while (!CatanRules.isFinished(state) && moves++ < 20_000) {
+            for (me in 0 until 3) {
+                val seats = CatanSeats(me, listOf("A", "B", "C"))
+                val text = CatanText.prompt(state, seats, setupVertexChosen = false, building = null)
+                assertTrue("blank prompt in ${state.phase} for seat $me", text.isNotBlank())
+            }
+            val seat = CatanRules.currentSeat(state) ?: break
+            state = CatanRules.applyMove(state, seat, ai.chooseMove(state, seat, CatanRules.legalMoves(state, seat)))
+        }
+    }
+
+    @Test
+    fun `every progress card has a name and a description`() {
+        ProgressType.entries.forEach {
+            assertTrue(CatanText.progress(it).isNotBlank())
+            assertTrue("no help for $it", CatanText.progressHelp(it).length > 10)
+        }
+    }
+
+    @Test
+    fun `the setup screen offers each rule set its own targets and switches sensibly`() {
+        assertEquals(listOf(5, 8, 10, 12), catanPointsChoices(CatanRuleSet.BASE))
+        assertEquals(listOf(8, 10, 13, 15), catanPointsChoices(CatanRuleSet.CITIES_AND_KNIGHTS))
+        assertEquals(10, catanDefaultPoints(CatanRuleSet.BASE))
+        assertEquals(13, catanDefaultPoints(CatanRuleSet.CITIES_AND_KNIGHTS))
+
+        val base = CatanOptions()
+        val ck = catanSwitchRules(base, CatanRuleSet.CITIES_AND_KNIGHTS)
+        assertEquals(CatanRuleSet.CITIES_AND_KNIGHTS, ck.ruleSet)
+        assertEquals("the published target for the new rules", 13, ck.pointsToWin)
+        assertEquals(10, catanSwitchRules(ck, CatanRuleSet.BASE).pointsToWin)
+
+        // A short game picked on purpose is kept when both menus have it.
+        val short = catanSwitchRules(base.copy(pointsToWin = 8), CatanRuleSet.CITIES_AND_KNIGHTS)
+        assertEquals(8, short.pointsToWin)
+        assertEquals(3, ck.playerCount)
+    }
+}

app/src/test/java/org/prolibertate/games/ui/game/catan/CatanHudTest.kt

@@ -0,0 +1,56 @@
+package org.prolibertate.games.ui.game.catan
+
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertNotNull
+import org.junit.Assert.assertNull
+import org.junit.Test
+import org.prolibertate.games.game.catan.BuildRoad
+import org.prolibertate.games.game.catan.BuildSettlement
+import org.prolibertate.games.game.catan.EndTurn
+
+/** The pure half of the landscape HUD: drag-to-build snapping and the staged ✓ / ✗ placement. */
+class CatanHudTest {
+
+    @Test
+    fun `a build tap is staged, not sent, but only while a build mode is armed`() {
+        val road = BuildRoad(0)
+
+        val outcome = TapOutcome.Submit(road)
+        assertEquals(road, CatanInteraction.stageable(outcome, BuildKind.ROAD))
+        assertNull(CatanInteraction.stageable(outcome, null))
+        // Ending the turn is never a placement.
+        assertNull(CatanInteraction.stageable(TapOutcome.Submit(EndTurn), BuildKind.ROAD))
+        assertNull(CatanInteraction.stageable(TapOutcome.Ignored, BuildKind.ROAD))
+    }
+
+    @Test
+    fun `the ghost of a staged move sits on its crossing or its edge`() {
+        assertEquals(CatanInteraction.Spot(vertex = 4), CatanInteraction.spotOf(BuildSettlement(4)))
+        assertEquals(CatanInteraction.Spot(edge = 9), CatanInteraction.spotOf(BuildRoad(9)))
+        assertEquals(CatanInteraction.Spot(), CatanInteraction.spotOf(null))
+    }
+
+    @Test
+    fun `a dragged finger snaps to the nearest lit crossing within reach, and off the board to nothing`() {
+        val layout = CatanGeometry.fit(800f, 600f)
+        val lit = setOf(3, 10, 21)
+        val targets = BoardTargets(vertices = lit)
+        val target = layout.vertex(10)
+
+        // A little off the crossing, well inside reach.
+        val near = Pt(target.x + layout.radius * 0.3f, target.y - layout.radius * 0.2f)
+        assertEquals(CatanInteraction.Spot(vertex = 10), CatanInteraction.snap(layout, targets, near, layout.radius * 1.2f))
+
+        // Far from every lit crossing.
+        assertNull(CatanInteraction.snap(layout, targets, Pt(-500f, -500f), layout.radius * 1.2f))
+    }
+
+    @Test
+    fun `with edges lit and no crossings, the drop snaps to an edge`() {
+        val layout = CatanGeometry.fit(800f, 600f)
+        val targets = BoardTargets(edges = setOf(5, 6))
+        val mid = layout.edgeMidpoint(6)
+        assertNotNull(CatanInteraction.snap(layout, targets, mid, layout.radius))
+        assertEquals(CatanInteraction.Spot(edge = 6), CatanInteraction.snap(layout, targets, mid, layout.radius))
+    }
+}

docs/RE-catan-universe.md

@@ -0,0 +1,73 @@
+# Catan Universe 2.7.5 — what the reverse engineering showed
+
+Source: `Catan+Universe_2.7.5_APKPure.xapk` (Unity, IL2CPP). Method: the Unity scenes
+(`level3` is the match scene) were parsed with UnityPy for the uGUI hierarchy (names,
+anchors, sizes, which objects start hidden), and `global-metadata.dat` was searched for
+class, method and game-action names. Code bodies were not decompiled; behaviour below
+that is not visible in a hierarchy is marked *inferred*.
+
+The game is **landscape-only**; the canvas is laid out against a 1920×1080 reference.
+
+## Match HUD (`InGameUI_mobile`)
+
+| Region | Contents |
+| --- | --- |
+| Top | `PlayerFrames`: one frame per player (avatar, colour, VP, card count, timer), a "shuffle stats" button at the right |
+| Bottom bar | `ResourceContainer`, centred (anchors 25–75 % of the width, 90 px tall): one entry per resource (Lumber, Brick, Wool, Grain, Ore; Cloth, Coins, Paper for C&K; Fish, Feather, Coca for other expansions, hidden otherwise) |
+| Bottom right | `BtnTurn` (140 px, roll / end turn), `BtnTrade` immediately to its left (counter-offer and "blocked" badge variants), `BtnAddDevCard`, a chat/log `BubblePanel` |
+| Left edge | `Drag&DropBuild`: a column of piece icons. **The player drags a piece from it onto the board** (`Drag&DropBuildRemove` is the drop target that cancels) |
+| Mid right | `ConfirmButtonGroup`: a ✓ (`CatanConfirmBuildButton`) over a ✗ (`CatanCancelBuildButton`). A drop only *previews*; the ✓ commits |
+| Board | `CandidateFactory` makes highlight markers for every legal spot (corner, edge, face); `QuickBuildTrigger{Corner,Edge,Face}` are hit zones for a one-tap/hold build; a candidate ticker shows the one-line instruction |
+| Centre | Played-card panel, progress-card chooser, discard panel (`CardPanel` slides up over the bottom bar with a header) |
+
+Gestures (`CatanGestureHandler`, `BaseGesture`, `TapHoldHandler`): one finger pans the
+board, two-finger pinch zooms (`GetPinchZoomMagnitude`, `AutomaticZoom`), tap selects a
+candidate, hold opens quick-build. Camera is a fixed-pitch table view.
+
+## Trade board (`TradeBoard_mobile`)
+
+A full-width panel that slides up over the bottom of the screen (`Animator`, collapsible):
+
+```
+┌────────────────────────────────────────────────────────────┬──────┐
+│ [Player] [Bank]   headline / description     ☐ Block trade │ P1 P2│ header
+├────────────────────────────────────────────────────────────┤ P3 P4│ (135 px)
+│ OPPONENT row  — cards you get (tinted by the opponent's    │      │
+│                 colour)                                    │ Hide │
+│        ⇣⇣⇣  arrows  (or the bank ratio chips 4:1 3:1 2:1)  │ Deny │
+│ PLAYER row    — cards you give (tinted by your colour)     │Accept│
+└────────────────────────────────────────────────────────────┴──────┘
+```
+
+* **Header.** A *Player / Bank* toggle (extra toggles for the Inka 3:2 / 2:1 rules). A
+  **Block trade** checkbox refuses all incoming offers. One round button per rival
+  (`Player1…5`, with a selected border) picks whom the offer is addressed to; none
+  selected means everyone.
+* **Content.** Two rows of resource cards separated by arrows. The top row is what you
+  *want*, the bottom row what you *give*. Tapping a card in a row adds one; tapping a
+  selected card removes one (*inferred from `AddFieldToTradePayment`/`ApplyCancelTradeResource`*).
+  In Bank mode a ratio row (`CardRatios`) shows the best rate per resource (harbours).
+* **Right column (180 px).** Hide/collapse, **Deny** (✗), **Accept** (✓). When you
+  are the one receiving an offer, ✓ accepts and the chip-icon variant `Icon_CounterOffer`
+  turns the ✓ into a *counter-offer* send. A circular turn timer wraps the ✓.
+* **Incoming offers** (`IncomingTradeContainer`) show in the same panel; the offerer's
+  colour tints the opponent row. Counter-offers land back in the proposer's panel with
+  an `AcceptCounterOfferButtonImage`.
+
+## Seafarers game actions (from the metadata)
+
+`CatanSeafarer_*_GameAction` names show what the mode adds to the base game:
+
+* **Ships:** `BuildShip`, `MoveShip` (only the ship at the open end of a route, not on
+  the turn it was built), `BuildFreeRoad`; roads and ships share `AvailableCandidatesRoadAndShip`.
+* **Pirate** alongside the robber: `RobberPirat_Move`, `RobberPirat_SelectPlayer`;
+  ships cannot be built or moved past a pirate-blocked edge.
+* **Gold fields:** `ChooseGoldfieldResource` (a hex that pays any resource of choice).
+* **Fog islands:** `Check_FogField`, `DistributeFogField` (hidden hex revealed when a
+  road/ship reaches it, the player takes the resource), `Shuffle_Islands`, `Shuffle_TileValueList`.
+* **Treasure islands / Oasis / Great Canal** are Catan Universe scenario extras and are
+  **not** part of the physical Seafarers rules; they are out of scope here.
+* **Setup:** `StartPhase_BuildSettlement`, `StartPhase_BuildRoadShip`, `PlaceValueChip`
+  (number tokens placed per scenario), `Shuffle_Harbors`.
+* **Island bonus:** special victory points for the first settlement on a new island
+  (`AllIslandIds`, `CatanIslandState`).

docs/README.md

@@ -24,9 +24,10 @@ Naming: the catalogue id, lowercase, e.g. `crazy8s` → `RULES-crazy8s.md`.
 | Golf | [RULES-golf.md](RULES-golf.md) |
 | Hearts | — (TODO) |
 | Kaiser | [RULES-kaiser.md](RULES-kaiser.md) |
-| Katan (catalogue id `catan`) | [RULES-catan.md](RULES-catan.md) |
+| Katan (catalogue id `catan`) | [RULES-catan.md](RULES-catan.md) — and its expansion rule set, [RULES-catan-ck.md](RULES-catan-ck.md) |
 | Klondike | — (TODO) |
 | Mastermind | [RULES-mastermind.md](RULES-mastermind.md) |
+| Meowdoku | [RULES-meowdoku.md](RULES-meowdoku.md) |
 | Morris | [RULES-morris.md](RULES-morris.md) |
 | Peg solitaire | — (TODO) |
 | Pirates | [RULES-pirates.md](RULES-pirates.md) |
@@ -42,6 +43,8 @@ Naming: the catalogue id, lowercase, e.g. `crazy8s` → `RULES-crazy8s.md`.
 
 - Build, CI, releases and OTA are described in the CI section of the root
   [README](../README.md).
+- [SAVED-GAMES.md](SAVED-GAMES.md) — how a game in progress is kept between sessions, and what is
+  not kept.
 - [UI-catan.md](UI-catan.md) — how the Katan screen is layered, and how to restyle,
   re-copy or re-lay-out it without touching the rules.
 - `licenses/` — third-party licences that must travel with the app

docs/RULES-catan-ck.md

@@ -0,0 +1,222 @@
+# Katan: Cities & Knights — implemented rules
+
+This is the second rule set of Katan (see [RULES-catan.md](RULES-catan.md) for the
+base game). It is chosen on the setup screen — **Rules: Base game / Cities &
+Knights** — and stored as `CatanOptions.ruleSet` (`CatanRuleSet.CITIES_AND_KNIGHTS`).
+A table plays one or the other; the choice reaches guests with the rest of the
+options.
+
+The expansion is a whole rule set rather than a toggle, because it replaces rules
+(no development cards, no Largest Army, a different seven) as well as adding them.
+Everything it needs lives behind `CatanState.ck`, which is `null` in the base game,
+so a base game's state and rules are untouched. The code is:
+
+| File | Holds |
+| --- | --- |
+| `CatanCkModel.kt` | the data: commodities, improvement tracks, progress cards, knights, the chore queue, every new move |
+| `CatanCk.kt` | the rules: legal moves, applying them, the roll, the barbarians, scoring |
+| `CatanCkAi.kt` | the computer opponent for this rule set |
+| `CatanRules.kt` | the single entry point; calls into `CatanCk` whenever `state.ck != null` |
+
+Behaviour is pinned by `CatanCkRulesTest` (each rule on a crafted position) and
+`CatanCkSelfPlayTest` (whole games, engine against engine). Three or four players,
+as in the base game.
+
+## Verification
+
+The rules were checked against the in-game almanac of Catan Universe (rules text
+only: costs, card wordings, the barbarian and improvement rules). Where the almanac
+is silent or ambiguous the reading chosen is listed under *Choices made here* below.
+
+## What changes from the base game
+
+| | Base game | Cities & Knights |
+| --- | --- | --- |
+| Points to win | 10 | **13** (setup offers 8 / 10 / 13 / 15) |
+| Development cards | 25-card deck | **none** — knights and progress cards replace them |
+| Largest Army | 5 *(see RULES-catan.md)* | **none** |
+| Longest Road | 5 *(see RULES-catan.md)* | **2** |
+| Second setup piece | settlement | **city** (resources only, no commodities) |
+| Dice | two | **two number dice + the event die** |
+| A seven | discard half over 7; robber moves | discard half over **7 + 2 per wall**; the robber **only moves after the first barbarian attack** |
+| Cities | 2 of a resource | forest: 1 lumber + **1 paper**; pasture: 1 wool + **1 cloth**; mountains: 1 ore + **1 coin**; hills / fields: 2 of the resource |
+
+## The dice
+
+The yellow die and the red die are added for production, as in the base game. The
+**event die** has three ships and one gate each of yellow (trade), blue (politics)
+and green (science). It is resolved **before** production:
+
+- **Ship** — the barbarians come one step nearer (they start 7 steps out).
+- **Gate** — every player with at least one level of improvement in that colour,
+  **in turn order from the roller**, whose **red die is no higher than their level**
+  in that track, draws a progress card of that colour.
+
+`RollDice(forced, event)` stages both for tests, like the base game's forced roll.
+An **Alchemist** played before the roll sets the two number dice (the event die is
+still rolled).
+
+## Commodities
+
+Three commodities — **cloth, coin, paper** — join the five resources. The bank holds
+12 of each (19 of each resource). Hands, discards, thefts and trades all treat them as
+cards; progress cards are not cards for any of these purposes.
+
+When the bank cannot meet the demand for a card type: with **one** seat owed it,
+that seat takes what is left; with **two or more** owed, nobody receives it.
+
+## The barbarians
+
+The strip shows how many steps away the ship is. On the seventh ship it **lands**:
+
+- Barbarian strength is the **number of cities on the board** (a metropolis is a city).
+- Catan's strength is the sum of the strengths of every **active** knight (basic 1,
+  strong 2, mighty 3).
+- If Catan's strength is **at least** the barbarians', Catan holds: the player with
+  the strictly highest contribution takes a **Defender of Catan** card (one point);
+  if several tie for highest, **each draws a progress card from a deck of their
+  choice** instead.
+- Otherwise Catan falls: among the players who own a city that is not a metropolis,
+  those who contributed **least** each lose one city, **to their own choice**. A lost
+  city becomes a settlement (or, if the seat has no settlement piece left, is removed),
+  and its wall goes. **A metropolis can never be pillaged.**
+- Either way every knight stands down, the ship returns to seven steps, and the
+  **robber wakes** — until now it has not been on the board.
+
+## Knights
+
+Each seat has **two knights of each strength** (six in all).
+
+| Action | Cost | Rule |
+| --- | --- | --- |
+| Hire | 1 ore + 1 wool | a **basic** knight on an empty crossing at the end of one of your roads; only if one of your two basic knights is free |
+| Activate | 1 grain | a sleeping knight wakes; only active knights count against the barbarians |
+| Promote | 1 ore + 1 wool | one level, once per knight per turn; a **mighty** knight needs **level three of politics** (the fortress); the next level's pieces must be free |
+| Move | — | an active knight moves along **its own roads** to an empty crossing, or onto a **strictly weaker** foreign knight, driving it off; it then rests |
+| Chase the robber | — | an active knight on a crossing of the robber's hex sends the robber off (only once the robber is awake); it then rests, and the robber move follows |
+
+- **A knight cannot act on the turn it woke.** It can be woken again after it acts.
+- A driven-off knight is moved by **its owner** along its own roads to any empty
+  crossing it can reach; if there is none, it is lost.
+- A knight is a wall, like an opposing building: roads cannot be laid past an enemy
+  knight, a settlement cannot be built on a knight, and the knight cuts **Longest Road**.
+- Knights can act (wake, move, chase) **before the roll** as well as after.
+
+## City walls
+
+2 brick, on a city without a wall, **three per player**. Each wall raises the hand
+limit on a seven by two (so a seven discards when you hold more than `7 + 2 × walls`).
+
+## City improvements
+
+Three tracks, five levels each, bought with the track's commodity: **trade (cloth,
+yellow), politics (coin, blue), science (paper, green)**. Level *n* costs *n* of the
+commodity. You must own a city to improve.
+
+| Track | Level 3 gives |
+| --- | --- |
+| Trade | commodities trade with the bank **2:1** |
+| Politics | knights may be promoted to **mighty** |
+| Science | the **aqueduct**: when the dice pay you nothing, take any resource |
+
+The level names (Trading Post … Grand Bazaar, Town Hall … Palace, Abbey … University)
+are this app's own.
+
+### Metropolises
+
+The first player to reach **level four** in a track takes that track's **metropolis**
+(a marker on one of their cities: +2 points; a city carries at most one). Reaching
+**level five** takes it from a holder who is still on four. A player with several
+cities chooses which; with one it is placed at once; a player with no free city
+**waits**, and claims it when a city is built.
+
+## Progress cards
+
+54 cards: 18 in each of three decks. A card played returns to the **bottom** of its
+deck. A hand holds **four**; a fifth must be given back at once. They can be played at
+any point of your own turn (before or after the roll), except where noted.
+
+**Science (green)** — Alchemist ×2 *(before the roll only)*, Crane ×2, Engineer, Inventor ×2,
+Irrigation ×2, Medicine ×2, Mining ×2, Printer, Road Building ×2, Smith ×2.
+
+**Politics (blue)** — Bishop ×2 *(after the first attack)*, Constitution, Deserter ×2,
+Diplomat ×2, Intrigue ×2, Saboteur ×2, Spy ×3, Warlord ×2, Wedding ×2.
+
+**Trade (yellow)** — Commercial Harbor ×2, Master Merchant ×2, Merchant ×6,
+Merchant Fleet ×2, Resource Monopoly ×4, Trade Monopoly ×2.
+
+**Printer** and **Constitution** are one point each and are **laid face up the moment
+they are drawn**; they never sit in a hand.
+
+How each plays is shown on the card in the app (`CatanText.progressHelp`); the engine's
+behaviour is in `CatanCk.applyProgress`. Points worth knowing:
+
+- **Saboteur** hits every other player with **as many points as you or more**, who each
+  discard half their cards (rounded down). **Wedding** takes two cards (or what they
+  have) from each player with **more** points. **Master Merchant** needs a victim with
+  more points, and takes two cards you choose.
+- **Spy**: you see the target's progress cards and take one; nobody else sees them.
+- **Merchant**: placed beside one of your buildings; you trade that hex's resource 2:1
+  and hold a victory point until someone else plays a Merchant.
+- **Deserter**: the victim removes a knight of *their* choice; you place a free one of the
+  same strength (or a basic if yours is not free), awake or asleep as theirs was.
+- **Diplomat**: removes a road with a loose end (an end touching no other road, building
+  or knight); if it was yours you may rebuild it anywhere for free.
+- **Inventor** swaps two tokens, never a 2, 6, 8 or 12.
+
+## The chore queue
+
+Anything that needs an answer from somebody — a discard, a city to lose, a progress card
+to hand over, a metropolis site, a knight to place — is queued as a **chore**
+(`CatanPhase.CHORE`, `CkState.chores`). The game waits on the seat the first chore names
+(not always the player whose turn it is), then resumes where `CkState.back` says. This is
+how a seven, a barbarian landing, a wedding or a spy are all one mechanism, and why
+the AI and the network driver needed no new concepts.
+
+The two free-form chores — **discarding** and **handing over** cards — are structural
+like the base game's trade offers: the engine checks them in `isLegalMove` and the legal
+list carries one example, so a seat is never without a move.
+
+## Scoring and winning
+
+Settlement 1, city 2, **metropolis +2**, **Longest Road 2**, **Defender of Catan 1** each,
+**Printer / Constitution 1** each, **the Merchant 1**. Nothing is hidden. Win at 13 (default),
+checked after every move and when a turn arrives.
+
+## Choices made here, and why
+
+- **The red die must be no higher than the improvement level** to draw a progress card
+  (level 1 draws on a 1, level 5 on 1–5). The almanac says the red die must match a
+  number on one of your improvements and that the number rises with the level; this is
+  the reading that makes both true.
+- **One resource is offered to every player for a Commercial Harbor.** The printed card
+  lets you offer a different one to each.
+- **The merchant cannot go on the desert**, which produces nothing to trade.
+- **Improvements need a city** to be built.
+- **A 3:1 harbour trades commodities too**; a 2:1 harbour trades only its own resource.
+- **A knight that cannot find a refuge is lost**, as the almanac says of an intrigue.
+- **A claim on a metropolis with no city to carry it waits** and is made when a city is
+  built.
+- **Domestic trade** works as in the base game — an offer to one seat or to the whole
+  table, asked in seat order, each seat accepting, declining or countering — and may
+  include commodities (`OfferGoods`, `CounterGoods`; accepting and dismissing counters
+  reuse the base game's `AcceptCounter` and `DismissCounters`).
+- **No Seafarers, no 5–6 player extension**, no scenario or variant of any kind.
+
+## The computer opponent
+
+`CatanCkAi` plays a safe, unambitious game: it settles and raises cities as the base AI
+does, spends commodities on improvements as soon as it can (leaning to politics), hires
+and wakes knights as the barbarians draw near, chases the robber off hexes it needs, plays
+the progress cards whose value is obvious, and answers every chore with the card it values
+least. It never plans a knight's route, never plays an Alchemist, Inventor, Diplomat,
+Deserter or Intrigue, and makes no domestic offers (though it answers them). Every engine
+game in `CatanCkSelfPlayTest` ends in a win at thirteen points.
+
+## Known gaps
+
+- The screen is built and its logic is tested, but **not yet verified on two real
+  devices**; the catalogue entry stays a dev-channel preview.
+- No animation for the event die, the barbarian landing or a knight's move.
+- The Commercial Harbor offers a single resource type (see above).
+- The AI is not a strong opponent and makes no claim to be.

docs/RULES-catan.md

@@ -12,14 +12,27 @@ players, as published.
 The engine is a pure state machine (`CatanRules`) with no Android types, and its
 behaviour is pinned by `CatanBoardTest`, `CatanRulesTest` and `CatanAiTest`.
 
+## Rule sets
+
+A table plays one of two rule sets, chosen on the setup screen
+(`CatanOptions.ruleSet`):
+
+- **Base game** — everything in this document.
+- **Cities & Knights** — the expansion, documented in
+  [RULES-catan-ck.md](RULES-catan-ck.md). It reuses this document's board, setup,
+  building, robber and trade rules and changes or replaces the rest; its state lives
+  behind `CatanState.ck`, which is `null` in the base game.
+
 ## Table
 
+- **Rules — *toggle*.** Base game or Cities & Knights (`CatanOptions.ruleSet`).
 - **Players — *toggle*.** Three or four. `CatanOptions.playerCount`; the engine
   refuses anything else.
 - **Points to win — *toggle*.** Defaults to 10. `CatanOptions.pointsToWin`, at
   least 2. A lower target makes a test game short.
 
-The setup screen exposes both (players: 3 or 4; game to 5, 8, 10 or 12 points).
+The setup screen exposes all three (players: 3 or 4; game to 5, 8, 10 or 12 points in the
+base game, 8, 10, 13 or 15 in Cities & Knights, whose published target is 13).
 
 ## Board
 
@@ -122,17 +135,32 @@ is the same code path.
 
 ### Domestic
 
-An offer names **one** addressee and two card multisets: what the offerer gives,
-what they want. There are no counter-offers and no open auctions in v1.
+An offer is addressed to **one** seat or, with `to = null`, to **everyone**, and
+names two card multisets: what the offerer gives, what they want.
+
+Seats are asked **one at a time**, in seat order after the offerer (seats holding
+no cards are skipped; an addressed offer asks only its addressee). The seat being
+asked may:
+
+- **accept** — the trade happens at once and the offer closes (first accept wins);
+- **decline** — the offer moves on to the next seat;
+- **counter** (`CounterTrade`) — propose different terms: what they would give and
+  what they want from the offerer. A counter must differ from the offer as made
+  (that is an accept), and both sides must hold the cards. The offer moves on.
+
+When every seat has answered and nobody accepted: with no counters the offer
+simply lapses; with counters the phase becomes `TRADE_COUNTERS` and the offerer
+either **takes one** (`AcceptCounter(seat)`, still checked for affordability) or
+**turns them all down** (`DismissCounters`).
 
 An offer is legal only when the offerer's turn is in PLAYING, the addressee is
 another seat, both legs are non-empty, the two legs are not the same multiset
 (`countOf(give) != countOf(get)` — like-for-like is not a trade), and the
 offerer actually holds the cards being offered.
 
-The addressee may **accept** only if they hold what was asked and the offerer
-still holds what was promised; otherwise only **decline** is offered. A decline
-clears the table and leaves every card where it was.
+A seat may **accept** only if it holds what was asked and the offerer still holds
+what was promised; otherwise only decline (or counter) is offered. A refusal
+leaves every card where it was.
 
 Offers are free-form intents rather than enumerated moves (the space of card
 multisets is combinatorial), so they are validated structurally by
@@ -292,15 +320,18 @@ timing rules; Longest Road and Largest Army worth five; victory at ten.
 - **Year of Plenty two-of-a-kind needs the bank to hold both cards**, not one.
 - **The robber must move.** Some printings allow staying put; this engine always
   requires a different hex.
-- **Offers are one-to-one, no auctions or counter-offers** in v1.
+- **Offers may be open to the whole table** and can be countered; the first accept wins (see Trading).
 
 ## Known gaps
 
-- **No domestic auction or counter-offer.** An offer is addressed to a single
-  seat. Open trading to the whole table, and counter-offers, are the obvious next
-  step and are not implemented.
-- **No player-to-player trade over the wire beyond accept/decline.** The engine
-  supports it; whether the UI surfaces it is the screen task's concern.
+- **Longest Road and Largest Army are worth 5 each here.** The published base game awards
+  **2** each (Catan Universe's almanac says so for Largest Army, and the printed rules
+  for both). Cities & Knights scores Longest Road at 2, as printed. Left unchanged in
+  the base game so far; it is a one-constant change in `publicVictoryPoints`.
+- **A bank short of a resource pays nobody that roll**, even when only one player is owed
+  it. The published ruling lets a lone claimant take what is left; Cities & Knights does.
+- **No timer or cancel on offers.** An offer waits for each asked seat in turn; the offerer cannot withdraw it mid-round, and a player who never answers stalls the table.
+- **The AI never counters.** It accepts, declines, and picks among counters it is sent, but does not propose them.
 - **No trading away a development card.** Not part of the base game.
 - **The screen is built, not yet verified on two devices.** The Katan screen and
   setup options exist (see [UI-catan.md](UI-catan.md)); the catalogue entry is a

docs/RULES-meowdoku.md

@@ -0,0 +1,98 @@
+# Meowdoku
+
+A board of colours, and a cat in every row, column and colour — no two sharing
+even a corner.
+
+## The puzzle
+
+The board is **N by N** and coloured into **N regions**. Exactly one cat hides
+in every row, every column and every region, and no two cats may touch — not
+along a side and not at a corner, so a cat rules out all eight squares around
+itself. Those four constraints together always leave exactly one arrangement.
+
+Uniqueness is not decoration. The game is deduction, and a second answer means
+a square the player cannot prove either way. Every board is therefore generated
+and then searched: build the colours, count the ways a board can be answered,
+and if it is more than one, throw the board away and deal another. The count is
+a plain depth-first search over the rows with the obvious exclusions propagated,
+and it sees only the colours and the rules — never the cats it was grown from.
+
+## Playing it
+
+Controls are the original's, and they carry the game's whole psychology:
+
+- **One tap crosses a square over.** Free, instant, erasable — the note you
+  make while thinking.
+- **A second tap on the same square within 350 ms is the cat attempt.** The
+  board judges it against the answer it was dealt: correct, the cross is
+  replaced by a cat; wrong, the cross stays and a heart goes. This is why a
+  guess feels like a decision: your own note has to survive one more tap
+  before it becomes a bet.
+- **Drag to cross a line.** The stroke paints the same note every square it
+  enters: start on a blank square and it crosses the row or column you drag
+  along; start on a crossed square and the stroke erases them instead. Cats
+  are skipped — placed cats are permanent.
+
+A square you pencilled over can still be tapped for a cat, and the cross is
+forgiven: the attempt replaces it if it is right. The one thing no gesture
+undoes is a cat once placed.
+
+The original ships a fifth gesture — a **draft** scratchpad mode, a tool you
+buy, where crosses and cats are laid down without judgement and applied all at
+once — and it is left out here with the rest of the shop: a scratchpad whose
+notes cost nothing is what tapping already is.
+
+A **Hint** spends a token and shows the cat in the first row that still lacks
+one, replacing any cross drawn over it. The original sells these as tools; here
+they are simply counted, three per board by default, which keeps the hint a
+decision rather than a reflex.
+
+## The heart
+
+Why a wrong tap costs anything at all: the puzzle is only hard if guessing is.
+A board with no penalty is a board you can solve by tapping every square, and
+the hearts are what make the deduction on a colour you have not reasoned about
+yet feel like a choice. Three is the number the original deals, and it stays
+three by default.
+
+## Options
+
+| | |
+| --- | --- |
+| **Board** | 4×4 up to 10×10; the number of cats equals the side |
+| **Hearts** | 1 to 5, default 3 |
+| **Hints** | 0 to 3, default 3 |
+
+Boards are dealt from the table's seed, so a saved game resumes to the same
+cats in the same colours, and **New puzzle** moves the seed to deal a different
+board. Smaller sides are gentler: a 4×4 is the shortest way to learn what
+no-touch does to a corner, and the ten-wide boards are for people who have
+already made that mistake.
+
+## How a board is dealt
+
+The order matters, and it is the order the original game uses:
+
+1. **Settle the cats first.** One per row, one per column, no two touching,
+   chosen by backtracking over shuffled column orders.
+2. **Grow the colours around them.** Each region starts as its cat's square and
+   expands outwards one square at a time; some regions are grown as straight
+   bars along the cat's row or column, which is what stops the board reading as
+   texture, and the rest take whichever neighbour is smallest so nothing
+   sprawls while another dies young.
+3. **Check the answer.** Count solutions up to two; keep the board only when
+   the count comes back exactly one.
+
+The generator's rejection loop is why the same seed can take a few attempts:
+most boards are unique on the first try, and the odd seed has to walk until it
+finds one.
+
+## Where this engine differs from the original
+
+The app is a game collection, not a live-service puzzle, so what sits around
+the original's gameplay is left behind: lives-as-monetisation (watching an ad
+for a heart), daily streaks and leaderboards, an Elo-matched bank of
+hand-authored levels, and the cosmetic layer (cat animations, combo feedback,
+confetti). This engine **deals its boards from a seed** instead of shipping a
+level bank, and the rules are the part worth keeping: the cats, the colours,
+the no-touch, the hearts, the one answer.

docs/SAVED-GAMES.md

@@ -0,0 +1,43 @@
+# Saved games
+
+A game played against the computer (or on one device) is kept as it is played, and can be
+picked up again after the app has been closed.
+
+## What the player sees
+
+- **Main menu → Continue.** Each game left half-played is listed, most recent first
+  ("Chess · saved 5 minutes ago"); tapping it resumes.
+- **A game's setup screen** shows a *Game in progress* card with **Resume** and **Discard**.
+  Starting a new game from that screen replaces the saved one.
+- **Leaving the table** (the back arrow, or the app being closed or sent to the background)
+  keeps the position. **End game → End the game** is the deliberate way to throw it away.
+- A game that is **finished** is not kept.
+- A **networked** table is not kept: the other player's seat cannot be held for them. Only a
+  table with no remote human at it (`PlayerKind.HUMAN_REMOTE`) is saved.
+
+One slot per game: there is one saved Chess game, one saved Katan game, and so on.
+
+## How it works
+
+| Piece | Where | Does |
+| --- | --- | --- |
+| `SavedMatch`, `SavedGameStore` | `game/engine/SavedGame.kt` | one JSON file per game under `filesDir/saved-games/`, written atomically (temp file, then renamed); an unreadable file is deleted and read as absent |
+| `MatchController.onHostState`, `restore` | `net/MatchController.kt` | the host reports every position it reaches; `restore(json)` starts the table from a saved position instead of dealing |
+| `MatchSaver` | `net/MatchSaver.kt` | takes the newest position and writes it off the main thread; `flush()` writes synchronously on leaving or on `ON_STOP`; `discard()` forgets the game |
+| `StartMatch` | `ui/PlayScreen.kt` | wires the two together for every game; consumes the resume state once, so a solitaire "new deal" is not put back |
+| `LocalEndGameHandle` | `ui/EndGameHandle.kt` | how each *End game* dialog tells the table to forget its save |
+
+What is saved is `rules.encodeState` of the **host's true state** (hidden cards included),
+plus the `TableConfig` (seed, seats, options) and the local seat. Nothing in the store knows
+which game it is holding, so a new game is saved with no work, provided its state encodes.
+
+A save this build cannot decode (one written by an older version whose state has since
+changed shape) is thrown away and a fresh game is dealt.
+
+## Tests
+
+- `SavedGameStoreTest` — the files: round trip, one slot, ordering, corruption, a cut-off write.
+- `MatchSaverTest` — saving as a table is played, resuming from a save, finished games, flush, discard.
+- `SaveRoundTripAllGamesTest` — **every game in the catalogue**: the whole state is encoded and
+  decoded at every move of a computer-played game, and play carries on from the decoded copy.
+  A new game should be added to it.

docs/UI-catan.md

@@ -22,6 +22,8 @@ truth, so the UI can only ever offer a move the rules would accept.
 | **Board drawing** | `CatanBoardView.kt` | The `Canvas`: tiles, tokens, ports, robber, roads, pieces, highlights | Change how a piece is drawn (art, shapes, animation) |
 | **Panels** | `CatanPanels.kt` | Resource tiles, hand, player cards, dice, action bar, log | Restyle or rearrange widgets |
 | **Dialogs** | `CatanDialogs.kt` | Discard, robber victim, play card, trade, trade reply, game over | Change a dialog's flow or look |
+| **HUD** | `CatanHud.kt` | The landscape controls: build column, ✓ / ✗, round turn / trade buttons, pinch-pan board | Move or restyle a landscape control |
+| **Trade board** | `CatanTradeBoard.kt` | The base-game trade panel (offer, bank, reply) | Change how trades are composed or answered |
 | **Screen** | `CatanScreen.kt` | Wiring to `MatchController`, portrait/landscape layout, which dialog shows | Change the layout or add a new element |
 | **Previews** | `CatanPreviews.kt` | Android Studio previews of real positions | Iterate on the look without a match |
 
@@ -89,7 +91,8 @@ screen's UI state. The legal-move list stays the gate.
 | Seven | **Discard** dialog (forced); then taps a hex to move the robber; a victim dialog appears only if more than one player can be robbed |
 | Main turn | arms **Road / Settlement / City** and taps a highlighted spot; **Buy card**; **Play card**; **Trade**; **End turn** |
 | Road Building | taps highlighted edges, or **Done with roads** |
-| Offered a trade | **Accept / Decline** dialog (forced) |
+| Offered a trade | **Accept / Decline / Counter…** dialog (forced); *Counter…* opens a picker pre-filled with the mirror of the offer |
+| Counter-offers received | **Counter-offers** dialog: *Accept* beside the one to take, or *No deal* |
 | Game over | result dialog |
 
 Trade offers are free-form (two card multisets), so they are validated with
@@ -120,6 +123,34 @@ and play a game on a dev build.
 - The board has a content description but no per-hex semantics; a screen-reader
   mode would need one.
 
+## Cities & Knights on the screen
+
+The same layers carry the expansion; the screen only adds pieces, and **none of them
+decides what is legal** — each reads the engine's legal-move list.
+
+| Layer | What it adds |
+| --- | --- |
+| `CatanStyle.kt` | commodity colours, a colour per improvement track, the wall and barbarian colours, the awake-knight halo |
+| `CatanText.kt` | goods, track, knight and progress-card names and help text; the prompts for every chore |
+| `CatanInteraction.kt` | `BuildKind.WALL` / `KNIGHT`; chore taps; the moving-knight and armed-card modes; `knightActions`, `progressHand`, `goodsBankTrades` |
+| `CatanBoardView.kt` | shields for knights (strength dots; faded when asleep, white halo when awake), dashed walls, a pennant for each metropolis, the merchant coin, a faint robber until the first attack |
+| `CatanPanels.kt` | commodity tiles in the hand, the barbarian strip, the yellow / red / event dice, the extra player-card lines, the Improve and Progress buttons |
+| `CatanCkDialogs.kt` | goods picker (discard, wedding, harbour), improvements, progress cards, the knight menu, deck / aqueduct / spy / drop choices, goods trade |
+| `CatanScreen.kt` | the visual state: knight menu, moving knight, armed card, and which chore dialog shows |
+
+**Interaction model.** Tap one of your own knights (it gets a yellow ring when it can do
+something) for its menu: wake, promote, move or chase the robber. *Move* arms the board
+with the crossings the knight can reach. A progress card that needs a place on the board
+(Engineer, Medicine, Merchant, Diplomat, Intrigue, Inventor) closes the dialog and
+**arms** the board; the next tap plays it. Chores that are answered with a place — a city
+to lose, a metropolis site, a driven knight's refuge, a free knight — light the crossings
+on the board and the prompt line says what to tap; the others open a dialog that cannot
+be dismissed, because the game is waiting on it.
+
+**Testing.** `CatanCkInteractionTest` plays whole games and checks that for *every* legal
+move at *every* position some control (a tap, a button or a dialog choice) produces it, so
+a legal move with no way to make it — a stuck phone — fails the build.
+
 ## Status and known gaps
 
 The screen is **playable and feature-complete for the engine's rules**, but is
@@ -137,6 +168,27 @@ Not done yet, in rough priority order:
    it does not say which hexes paid out, so that needs either a diff of two states
    or an engine addition.
 3. Art: terrain textures, resource and harbour icons, a real robber pawn.
-4. Open trade to the whole table and counter-offers (an engine limitation too).
+4. A timer or cancel button on offers (the engine has neither).
 5. A board that shows the *last* move (a faint highlight of what just changed).
 6. Landscape polish on large tablets; the right-hand panel scrolls but is plain.
+
+## Landscape HUD and trade board (from Catan Universe)
+
+Landscape screens use the control scheme of Catan Universe's match view, redrawn in 2D
+(what was learned, and from where: [RE-catan-universe.md](RE-catan-universe.md)). Portrait keeps the stacked layout.
+
+* **Drag to build.** The left column holds Road / Settlement / City (and Wall / Knight in
+  Cities & Knights). Drag a piece onto the island: lit spots snap under the finger
+  (`CatanInteraction.snap`), release over one to **stage** it, then press **✓** to place or **✕**
+  to cancel (`CatanInteraction.stageable`, `spotOf`). A tap on a piece still arms the board for
+  tapping a spot. Setup placements, free roads and chores are not staged: they commit on tap.
+* **Pinch and pan** the island (`ZoomPanBox`). The board is drawn through a graphics layer, so
+  taps and drops arrive in board coordinates; hit-testing is unchanged.
+* **Round buttons**, bottom right: the big one is roll / end turn / done (whatever the engine
+  currently allows); ⇄ is trade; the small pair is buy / play card (Improve / Cards in C&K).
+* **Trade board** (`CatanTradeBoard`, base game): a panel over the bottom of the island with a
+  Bank / Player toggle, a round button per rival to address an offer to one player, a *get* row on
+  top, a *give* row below, and ▾ hide / ✕ clear / ✓ send on the right. Bank mode shows each resource's
+  ratio under the *give* card. An offer made to you opens the same panel read-only: ✓ accepts,
+  ✕ declines, *Counter…* makes the rows editable.
+  Cities & Knights goods trades and the counter-offer chooser still use dialogs.