Merge dev into Seafarers

Co-Authored-By: Claude Sonnet 5.5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01S8evMuUxrft6TQj6NdAoqQ

CLAUDE.md

@@ -1,78 +1,67 @@
-> **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`), Cities & Knights
+(`docs/RULES-catan-ck.md`, code in `game/catan/CatanCk*.kt`, state behind
+`CatanState.ck`, which is null in the base game) and Seafarers
+(`docs/RULES-catan-seafarers.md`, code in `game/catan/CatanSea*.kt`, state behind
+`CatanState.sea`). The base and Seafarers rules read the board from `state.topo`, not from
+`CatanBoard` directly, because a Seafarers map is not the 19-hex island
+(Cities & Knights is always the standard island and still uses `CatanBoard`). The
+Catan Universe reverse engineering that shaped the landscape HUD and trade board
+is in `docs/RE-catan-universe.md`. The screen is layered; see
+`docs/UI-catan.md` before changing it.
 
 ## Bash output is filtered before it reaches the model
 

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
@@ -361,12 +362,18 @@ object GameCatalog {
             maxPlayers = 4,
             teamBased = false,
             blurb = "Trade, build, and settle the island, in the base game or Cities & Knights.",
-            // 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,
+            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

@@ -34,6 +34,11 @@ class CatanAi : GameAi<CatanState, CatanMove> {
 
             CatanPhase.AWAIT_ROLL -> legal.first { it is RollDice }
 
+            // Gold: take what the seat wants most.
+            CatanPhase.GOLD -> legal.filterIsInstance<PickGold>().maxByOrNull { pick ->
+                pick.cards.sumOf { want(it) }
+            } ?: legal.first()
+
             CatanPhase.DISCARDING -> chooseDiscard(state, seat, legal.filterIsInstance<Discard>())
 
             CatanPhase.ROBBER -> chooseRobber(state, seat, legal.filterIsInstance<MoveRobber>())
@@ -70,9 +75,10 @@ class CatanAi : GameAi<CatanState, CatanMove> {
      * worth is what it reaches past it.
      */
     private fun placeDirection(state: CatanState, place: SetupPlace): Double {
-        val far = CatanBoard.otherEnd(place.edge, place.vertex)
-        return CatanBoard.VERTEX_NEIGHBORS[far]
-            .filter { it != place.vertex && it !in CatanBoard.VERTEX_NEIGHBORS[place.vertex] }
+        val topo = state.topo
+        val far = topo.otherEnd(place.edge, place.vertex)
+        return topo.VERTEX_NEIGHBORS[far]
+            .filter { it != place.vertex && it !in topo.VERTEX_NEIGHBORS[place.vertex] }
             .maxOfOrNull { spotValue(state, it) }
             ?: 0.0
     }
@@ -94,9 +100,9 @@ class CatanAi : GameAi<CatanState, CatanMove> {
         require(moves.isNotEmpty()) { "No legal robber move" }
         val points = CatanRules.publicVictoryPoints(state)
         return moves.maxByOrNull { move ->
-            val hex = CatanBoard.hexIndex.getValue(move.hex)
+            val hex = state.topo.hexIndex.getValue(move.hex)
             var score = 0.0
-            for (v in CatanBoard.HEX_CORNERS[hex]) {
+            for (v in state.topo.HEX_CORNERS[hex]) {
                 val building = state.buildings[v] ?: continue
                 if (building.owner == seat) continue
                 val worth = if (building.type == BuildingType.CITY) 2 else 1
@@ -124,6 +130,12 @@ class CatanAi : GameAi<CatanState, CatanMove> {
             spotValue(state, it.vertex)
         }?.let { return it }
 
+        // Seafarers: a ship toward an island nobody has landed on is worth more than a card.
+        legal.filterIsInstance<BuildShip>()
+            .filter { shipValue(state, seat, it.edge) > 0.5 }
+            .maxByOrNull { shipValue(state, seat, it.edge) }
+            ?.let { return it }
+
         // A knight is worth playing whenever one is playable: it blocks an
         // opponent's best hex and marches toward Largest Army.
         legal.filterIsInstance<PlayKnight>().firstOrNull()?.let { return it }
@@ -142,6 +154,12 @@ class CatanAi : GameAi<CatanState, CatanMove> {
 
         legal.filterIsInstance<BuyDevCard>().firstOrNull()?.let { return it }
 
+        // Seafarers: a ship that heads for a settlement spot worth having.
+        legal.filterIsInstance<BuildShip>()
+            .filter { shipValue(state, seat, it.edge) > 0.15 }
+            .maxByOrNull { shipValue(state, seat, it.edge) }
+            ?.let { return it }
+
         // A paid road only when it reaches toward a spot worth settling.
         legal.filterIsInstance<BuildRoad>()
             .filter { roadValue(state, it) > 0.1 }
@@ -301,13 +319,13 @@ class CatanAi : GameAi<CatanState, CatanMove> {
         if (state.buildings[vertex] != null) return -1.0
         var value = 0.0
         val kinds = mutableSetOf<Resource>()
-        for (h in CatanBoard.VERTEX_HEXES[vertex]) {
+        for (h in state.topo.VERTEX_HEXES[vertex]) {
             val resource = state.terrains[h].produces ?: continue
             value += CatanBoard.numberOdds(state.numbers[h]) / 36.0 * want(resource)
             kinds += resource
         }
         value += 0.12 * kinds.size // variety keeps a build plan alive
-        for (e in CatanBoard.VERTEX_EDGES[vertex]) {
+        for (e in state.topo.VERTEX_EDGES[vertex]) {
             val port = state.ports.firstOrNull { it.edge == e } ?: continue
             value += if (port.resource == null) 0.1 else 0.2
         }
@@ -320,15 +338,52 @@ class CatanAi : GameAi<CatanState, CatanMove> {
      */
     internal fun roadValue(state: CatanState, move: BuildRoad): Double {
         var best = 0.0
-        val (from, to) = CatanBoard.EDGE_VERTICES[move.edge]
+        val (from, to) = state.topo.EDGE_VERTICES[move.edge]
         for (endpoint in listOf(from, to)) {
-            for (near in CatanBoard.VERTEX_NEIGHBORS[endpoint]) {
+            for (near in state.topo.VERTEX_NEIGHBORS[endpoint]) {
                 best = maxOf(best, spotValue(state, near) * 0.8)
             }
         }
         return best
     }
 
+    /**
+     * What a ship on [edge] is heading for: the best open settlement spot reachable by sea from
+     * its far end (the end the fleet does not already hold), discounted by how far off it is,
+     * with a bonus for an island nobody has landed on.
+     */
+    internal fun shipValue(state: CatanState, seat: Int, edge: Int): Double {
+        val topo = state.topo
+        val sea = state.sea ?: return 0.0
+        val (a, b) = topo.EDGE_VERTICES[edge]
+        fun held(v: Int): Boolean =
+            state.buildings[v]?.owner == seat || topo.VERTEX_EDGES[v].any { sea.ships[it] == seat }
+        val front = listOf(a, b).filter { !held(it) }.ifEmpty { return 0.0 }
+        var best = 0.0
+        val seen = mutableSetOf<Int>()
+        var frontier = front
+        var depth = 0
+        while (frontier.isNotEmpty() && depth <= 5) {
+            val next = mutableListOf<Int>()
+            for (v in frontier) {
+                if (!seen.add(v)) continue
+                if (CatanRules.vertexOpenForSettlement(state, v)) {
+                    val island = topo.vertexIsland[v]
+                    val fresh = island >= 0 && island != sea.home && sea.islandBonus[island] == NO_PLAYER
+                    val value = (spotValue(state, v) + if (fresh) 0.5 else 0.0) * Math.pow(0.85, depth.toDouble())
+                    best = maxOf(best, value)
+                }
+                for (e in topo.VERTEX_EDGES[v]) {
+                    if (!topo.edgeSea[e] || sea.ships[e] != NO_PLAYER) continue
+                    next += topo.otherEnd(e, v)
+                }
+            }
+            frontier = next
+            depth++
+        }
+        return best
+    }
+
     /** How much the AI wants to hold one card of [resource]. */
     internal fun want(resource: Resource): Double = when (resource) {
         Resource.ORE -> 1.20 // the city

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

@@ -5,13 +5,14 @@ import kotlin.math.atan2
 import kotlin.random.Random
 
 /**
- * The island as geometry: the 19 hexes, the 54 shared vertices, the 72
- * shared edges, the coast and the nine harbour positions.
+ * The geometry of one board: its hexes, the shared vertices and edges between
+ * them, and which hexes are land.
  *
  * Everything is derived once, deterministically, from axial coordinates —
  * there is no randomness and no state here; the layout of a particular
- * game (which terrain and number sits on which hex) is [generate], and the
- * live state lives in [CatanState].
+ * game (which terrain and number sits on which hex) is generated elsewhere
+ * ([CatanBoard.generate], [SeaBoards.generate]), and the live state lives in
+ * [CatanState].
  *
  * Coordinates: hexes are addressed axially ((q, r), pointy-top). Every
  * position is kept on an exact integer lattice so vertices shared by
@@ -20,41 +21,25 @@ import kotlin.random.Random
  * six corners follow the offsets in [CORNER_OFFSETS]. Vertex positions are
  * in half-units of the hex grid; rendering scales and flips them (lattice
  * +Y is toward the top of the board).
+ *
+ * The standard island ([CatanBoard.base]) is the 19-hex hexagon. A Seafarers
+ * map is a larger frame whose hexes are mostly sea; [land] says which.
  */
-object CatanBoard {
-
-    /** The 19 hexes: every (q, r) within distance 2 of the centre. */
-    val HEXES: List<HexCoord> = buildList {
-        for (r in -2..2) {
-            for (q in -2..2) {
-                if (hexDistance(q, r, 0, 0) <= 2) add(HexCoord(q, r))
-            }
-        }
-    }
+class Topology(
+    /** Every hex of the frame, land and sea alike. */
+    val HEXES: List<HexCoord>,
+    /** Whether each hex is land. The base island is all land; Seafarers maps are mostly sea. */
+    val land: List<Boolean> = List(HEXES.size) { true },
+    /** The standard 19-hex island: checks its counts and uses the fixed nine-harbour frame. */
+    private val standardFrame: Boolean = false,
+    /** Harbours wanted on a non-standard map. */
+    harbours: Int = 0,
+) {
 
     val HEX_COUNT: Int = HEXES.size
 
     val hexIndex: Map<HexCoord, Int> = HEXES.withIndex().associate { (i, hex) -> hex to i }
 
-    /**
-     * Corner k of a hex, as a lattice offset from its centre. Pointy-top:
-     * corner 0 is the top corner, then clockwise.
-     */
-    private val CORNER_OFFSETS = listOf(
-        0 to 2, 1 to 1, 1 to -1, 0 to -2, -1 to -1, -1 to 1,
-    )
-
-    /** Unit steps to a hex's six neighbours, matching the corner order. */
-    private val NEIGHBOR_STEPS = listOf(
-        0 to 1, 1 to 0, 1 to -1, 0 to -1, -1 to 0, -1 to 1,
-    )
-
-    /** The six board-corner hexes: pairwise non-adjacent by construction. */
-    private val CORNER_HEXES = listOf(
-        HexCoord(2, 0), HexCoord(0, 2), HexCoord(-2, 2),
-        HexCoord(-2, 0), HexCoord(0, -2), HexCoord(2, -2),
-    )
-
     // -----------------------------------------------------------------------
     // Vertices and edges
     // -----------------------------------------------------------------------
@@ -93,9 +78,28 @@ object CatanBoard {
     /** The coastal edges (those with only one hex) in ring order. */
     val COASTAL: List<Int>
 
-    /** The nine fixed harbour positions, spread around the coast. */
+    /** The harbour positions: nine on the standard frame. */
     val PORT_POSITIONS: List<Int>
 
+    // --- Land and sea (all land on the standard island) --------------------
+
+    /** A settlement may stand here: at least one of its hexes is land. */
+    val vertexLand: List<Boolean>
+
+    /** A road may lie here: at least one of its hexes is land. */
+    val edgeLand: List<Boolean>
+
+    /** A ship may sail here: at least one of its hexes is sea. */
+    val edgeSea: List<Boolean>
+
+    /** Which island each hex is on (a connected group of land hexes), or -1 for sea. */
+    val islandOf: List<Int>
+
+    val islandCount: Int
+
+    /** Which island each vertex touches, or -1 for open water. */
+    val vertexIsland: List<Int>
+
     init {
         // Vertices: assign ids in first-seen order over hexes then corners.
         val vertexIds = mutableMapOf<Pair<Int, Int>, Int>()
@@ -169,27 +173,99 @@ object CatanBoard {
 
         // The coast in walking order: sort the coastal edges by the angle of
         // their midpoint around the board centre, which is the lattice
-        // origin. The board is a hexagon, so this yields one closed ring.
+        // origin. The standard board is a hexagon, so this yields one closed ring.
         COASTAL = EDGE_HEXES.withIndex()
             .filter { it.value.size == 1 }
             .map { (e, _) -> e }
             .sortedBy { e -> angleOf(midpoint(e)) }
-        // Harbours sit roughly every third or fourth coastal edge, like the
-        // physical frame: nine positions, steps summing to the whole ring.
-        PORT_POSITIONS = buildList {
-            var at = 0
-            for (step in listOf(3, 4, 3, 3, 4, 3, 3, 4, 3)) {
-                add(COASTAL[at % COASTAL.size])
-                at += step
-            }
-        }.distinct()
 
-        check(HEX_COUNT == 19) { "A Catan island has 19 hexes, found $HEX_COUNT" }
-        check(VERTEX_COUNT == 54) { "A Catan island has 54 vertices, found $VERTEX_COUNT" }
-        check(EDGE_COUNT == 72) { "A Catan island has 72 edges, found $EDGE_COUNT" }
-        check(COASTAL.size == 30) { "The coast has 30 edges, found ${COASTAL.size}" }
-        check(PORT_POSITIONS.size == 9) { "Nine harbours, found ${PORT_POSITIONS.size}" }
-        check(PORT_POSITIONS.all { EDGE_HEXES[it].size == 1 }) { "Harbours must be coastal" }
+        vertexLand = List(VERTEX_COUNT) { v -> VERTEX_HEXES[v].any { land[it] } }
+        edgeLand = List(EDGE_COUNT) { e -> EDGE_HEXES[e].any { land[it] } }
+        edgeSea = List(EDGE_COUNT) { e -> EDGE_HEXES[e].any { !land[it] } }
+
+        // Islands: connected groups of land hexes.
+        val island = IntArray(HEX_COUNT) { -1 }
+        var islands = 0
+        for (h in 0 until HEX_COUNT) {
+            if (!land[h] || island[h] != -1) continue
+            val stack = ArrayDeque(listOf(h))
+            island[h] = islands
+            while (stack.isNotEmpty()) {
+                val at = stack.removeLast()
+                for (n in HEX_NEIGHBORS[at]) {
+                    if (land[n] && island[n] == -1) {
+                        island[n] = islands
+                        stack.addLast(n)
+                    }
+                }
+            }
+            islands++
+        }
+        islandOf = island.toList()
+        islandCount = islands
+        vertexIsland = List(VERTEX_COUNT) { v ->
+            VERTEX_HEXES[v].firstOrNull { land[it] }?.let { island[it] } ?: -1
+        }
+
+        PORT_POSITIONS = if (standardFrame) {
+            // Harbours sit roughly every third or fourth coastal edge, like the
+            // physical frame: nine positions, steps summing to the whole ring.
+            buildList {
+                var at = 0
+                for (step in listOf(3, 4, 3, 3, 4, 3, 3, 4, 3)) {
+                    add(COASTAL[at % COASTAL.size])
+                    at += step
+                }
+            }.distinct()
+        } else {
+            seaPorts(harbours)
+        }
+
+        if (standardFrame) {
+            check(HEX_COUNT == 19) { "A Catan island has 19 hexes, found $HEX_COUNT" }
+            check(VERTEX_COUNT == 54) { "A Catan island has 54 vertices, found $VERTEX_COUNT" }
+            check(EDGE_COUNT == 72) { "A Catan island has 72 edges, found $EDGE_COUNT" }
+            check(COASTAL.size == 30) { "The coast has 30 edges, found ${COASTAL.size}" }
+            check(PORT_POSITIONS.size == 9) { "Nine harbours, found ${PORT_POSITIONS.size}" }
+            check(PORT_POSITIONS.all { EDGE_HEXES[it].size == 1 }) { "Harbours must be coastal" }
+        }
+    }
+
+    /**
+     * Harbour sites on a map with islands: edges where land meets sea, taken
+     * round the map by angle about the land's centre, [count] of them as evenly
+     * spaced as the coast allows, never two sharing a corner.
+     */
+    private fun seaPorts(count: Int): List<Int> {
+        if (count <= 0) return emptyList()
+        val shore = (0 until EDGE_COUNT).filter { e ->
+            EDGE_HEXES[e].size == 2 && EDGE_HEXES[e].any { land[it] } && EDGE_HEXES[e].any { !land[it] }
+        }
+        if (shore.isEmpty()) return emptyList()
+        val landCentre = HEXES.indices.filter { land[it] }.let { hs ->
+            val pts = hs.map { hexCenter(it) }
+            (pts.sumOf { it.first } / pts.size.toDouble()) to (pts.sumOf { it.second } / pts.size.toDouble())
+        }
+        val ring = shore.sortedBy { e ->
+            val m = midpoint(e)
+            atan2(m.second - landCentre.second, m.first - landCentre.first)
+        }
+        val picked = mutableListOf<Int>()
+        val used = mutableSetOf<Int>()
+        val step = ring.size.toDouble() / count
+        for (i in 0 until count) {
+            val start = (i * step).toInt()
+            // The first edge at or after the ideal spot whose corners are free.
+            val e = (0 until ring.size).map { ring[(start + it) % ring.size] }.firstOrNull { cand ->
+                val (a, b) = EDGE_VERTICES[cand]
+                a !in used && b !in used && cand !in picked
+            } ?: continue
+            picked += e
+            val (a, b) = EDGE_VERTICES[e]
+            used += a
+            used += b
+        }
+        return picked
     }
 
     /** The other endpoint of [edge], given one [vertex] on it. */
@@ -207,19 +283,14 @@ object CatanBoard {
     /** Whether two hexes share an edge. */
     fun hexesAdjacent(a: Int, b: Int): Boolean = b in HEX_NEIGHBORS[a]
 
-    /** Hex-grid distance between two axial positions. */
-    fun hexDistance(q1: Int, r1: Int, q2: Int, r2: Int): Int {
-        val dq = q1 - q2
-        val dr = r1 - r2
-        return maxOf(kotlin.math.abs(dq), kotlin.math.abs(dr), kotlin.math.abs(dq + dr))
+    /** Lattice extent of the whole frame: min x, max x, min y, max y. */
+    val lattice: IntArray by lazy {
+        intArrayOf(
+            VERTEX_POS.minOf { it.first }, VERTEX_POS.maxOf { it.first },
+            VERTEX_POS.minOf { it.second }, VERTEX_POS.maxOf { it.second },
+        )
     }
 
-    /**
-     * How often a number is expected to come up, in thirty-sixths. A 6 or an
-     * 8 comes up five times in thirty-six, a 2 or a 12 once.
-     */
-    fun numberOdds(number: Int): Int = 6 - kotlin.math.abs(7 - number)
-
     private fun midpoint(edge: Int): Pair<Double, Double> {
         val (a, b) = EDGE_VERTICES[edge]
         val pa = VERTEX_POS[a]
@@ -230,6 +301,84 @@ object CatanBoard {
     private fun angleOf(point: Pair<Double, Double>): Double =
         atan2(point.second, point.first)
 
+    companion object {
+        /**
+         * Corner k of a hex, as a lattice offset from its centre. Pointy-top:
+         * corner 0 is the top corner, then clockwise.
+         */
+        private val CORNER_OFFSETS = listOf(
+            0 to 2, 1 to 1, 1 to -1, 0 to -2, -1 to -1, -1 to 1,
+        )
+
+        /** Unit steps to a hex's six neighbours, matching the corner order. */
+        private val NEIGHBOR_STEPS = listOf(
+            0 to 1, 1 to 0, 1 to -1, 0 to -1, -1 to 0, -1 to 1,
+        )
+
+        /** Hex-grid distance between two axial positions. */
+        fun hexDistance(q1: Int, r1: Int, q2: Int, r2: Int): Int {
+            val dq = q1 - q2
+            val dr = r1 - r2
+            return maxOf(kotlin.math.abs(dq), kotlin.math.abs(dr), kotlin.math.abs(dq + dr))
+        }
+
+        /**
+         * How often a number is expected to come up, in thirty-sixths. A 6 or an
+         * 8 comes up five times in thirty-six, a 2 or a 12 once.
+         */
+        fun numberOdds(number: Int): Int = 6 - kotlin.math.abs(7 - number)
+    }
+}
+
+/**
+ * The standard island: the 19 hexes, the 54 shared vertices, the 72 shared
+ * edges, the coast and the nine harbour positions. Every table below is the
+ * standard frame's [Topology]; the rules read the topology of the *state* they
+ * are working on ([CatanState.topo]), which is this one in every game but Seafarers.
+ */
+object CatanBoard {
+
+    /** The standard island's geometry. */
+    val base: Topology = Topology(
+        HEXES = buildList {
+            for (r in -2..2) {
+                for (q in -2..2) {
+                    if (Topology.hexDistance(q, r, 0, 0) <= 2) add(HexCoord(q, r))
+                }
+            }
+        },
+        standardFrame = true,
+    )
+
+    val HEXES: List<HexCoord> get() = base.HEXES
+    val HEX_COUNT: Int get() = base.HEX_COUNT
+    val hexIndex: Map<HexCoord, Int> get() = base.hexIndex
+    val VERTEX_POS: List<Pair<Int, Int>> get() = base.VERTEX_POS
+    val VERTEX_COUNT: Int get() = base.VERTEX_COUNT
+    val HEX_CORNERS: List<List<Int>> get() = base.HEX_CORNERS
+    val EDGE_VERTICES: List<Pair<Int, Int>> get() = base.EDGE_VERTICES
+    val EDGE_COUNT: Int get() = base.EDGE_COUNT
+    val VERTEX_EDGES: List<List<Int>> get() = base.VERTEX_EDGES
+    val VERTEX_NEIGHBORS: List<List<Int>> get() = base.VERTEX_NEIGHBORS
+    val VERTEX_HEXES: List<List<Int>> get() = base.VERTEX_HEXES
+    val EDGE_HEXES: List<List<Int>> get() = base.EDGE_HEXES
+    val EDGE_NEIGHBORS: List<List<Int>> get() = base.EDGE_NEIGHBORS
+    val HEX_NEIGHBORS: List<List<Int>> get() = base.HEX_NEIGHBORS
+    val COASTAL: List<Int> get() = base.COASTAL
+    val PORT_POSITIONS: List<Int> get() = base.PORT_POSITIONS
+
+    fun otherEnd(edge: Int, vertex: Int): Int = base.otherEnd(edge, vertex)
+    fun hexCenter(h: Int): Pair<Int, Int> = base.hexCenter(h)
+    fun hexesAdjacent(a: Int, b: Int): Boolean = base.hexesAdjacent(a, b)
+    fun hexDistance(q1: Int, r1: Int, q2: Int, r2: Int): Int = Topology.hexDistance(q1, r1, q2, r2)
+    fun numberOdds(number: Int): Int = Topology.numberOdds(number)
+
+    /** The six board-corner hexes: pairwise non-adjacent by construction. */
+    private val CORNER_HEXES = listOf(
+        HexCoord(2, 0), HexCoord(0, 2), HexCoord(-2, 2),
+        HexCoord(-2, 0), HexCoord(0, -2), HexCoord(2, -2),
+    )
+
     // -----------------------------------------------------------------------
     // Island generation
     // -----------------------------------------------------------------------

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

@@ -273,6 +273,9 @@ object CatanCk {
         CatanPhase.FREE_ROADS ->
             CatanRules.roadMoves(state, seat) + listOf<CatanMove>(EndFreeRoads)
 
+        // Seafarers is never combined with Cities & Knights.
+        CatanPhase.GOLD -> emptyList()
+
         CatanPhase.TRADE_PENDING -> {
             val offer = state.ck!!.goodsOffer
             if (offer == null) {

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

@@ -35,7 +35,7 @@ internal class CatanCkAi(private val ai: CatanAi) {
 
         CatanPhase.PLAYING -> choosePlaying(state, seat, legal)
 
-        CatanPhase.DISCARDING, CatanPhase.GAME_OVER -> legal.firstOrNull()
+        CatanPhase.DISCARDING, CatanPhase.GOLD, CatanPhase.GAME_OVER -> legal.firstOrNull()
             ?: error("Nothing to choose in phase ${state.phase}")
     }
 

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

@@ -39,6 +39,12 @@ enum class Terrain(val produces: Resource?) {
     HILLS(Resource.BRICK),
     MOUNTAINS(Resource.ORE),
     DESERT(null),
+
+    /** Seafarers: open water. Ships sail on it; nothing is built on it and nothing produces. */
+    SEA(null),
+
+    /** Seafarers: a gold field. A settlement beside it takes any resource its owner likes when its number rolls. */
+    GOLD(null),
 }
 
 /** Axial coordinate of one hex on the board. See [CatanBoard]. */
@@ -114,6 +120,9 @@ enum class CatanPhase {
     /** The player whose turn it is must roll the dice. */
     AWAIT_ROLL,
 
+    /** Seafarers: the first seat in [SeaState.gold] is choosing the resources its gold fields paid. */
+    GOLD,
+
     /** Players holding more than 7 resource cards discard half. */
     DISCARDING,
 
@@ -150,6 +159,9 @@ enum class CatanRuleSet {
 
     /** Cities & Knights: commodities, knights, barbarians, city improvements. */
     CITIES_AND_KNIGHTS,
+
+    /** Seafarers: ships, a pirate, gold fields and islands to settle (see `docs/RULES-catan-seafarers.md`). */
+    SEAFARERS,
 }
 
 @Serializable
@@ -230,9 +242,17 @@ data class CatanState(
     val log: List<String>,
     /** Everything Cities & Knights adds; null in the base game. */
     val ck: CkState? = null,
+    /** Everything Seafarers adds (ships, the pirate, islands); null in the other rule sets. */
+    val sea: SeaState? = null,
 ) {
     val playerCount: Int get() = options.playerCount
 
+    /** The geometry this game is played on: the standard island, or a Seafarers map. */
+    val topo: Topology get() = sea?.let { SeaBoards.topology(it.scenario) } ?: CatanBoard.base
+
+    /** Whether this table plays Seafarers. */
+    val isSea: Boolean get() = sea != null
+
     /** Whether this table plays Cities & Knights. */
     val isCk: Boolean get() = ck != null
 
@@ -377,3 +397,48 @@ data object EndTurn : CatanMove
 @Serializable
 @SerialName("endFreeRoads")
 data object EndFreeRoads : CatanMove
+
+/**
+ * Seafarers state: the ships, the pirate and the islands, alongside the base game's
+ * roads, robber and buildings (which keep working exactly as before).
+ */
+@Serializable
+data class SeaState(
+    val scenario: SeaScenario,
+    /** Owning seat per edge, or [NO_PLAYER]: a ship on that edge. Roads stay in [CatanState.roads]. */
+    val ships: List<Int>,
+    /** The hex the pirate occupies: always a sea hex. */
+    val pirate: Int,
+    /** Ships built this turn (they may not sail until the next) and whether a ship has sailed this turn. */
+    val builtThisTurn: List<Int> = emptyList(),
+    val shipMoved: Boolean = false,
+    /** Who holds the "new island" bonus for each island, or [NO_PLAYER]. The home island's is never awarded. */
+    val islandBonus: List<Int>,
+    /** The island the players start on. */
+    val home: Int,
+    /** Gold owed after a roll, front first: each seat chooses [GoldOwed.count] cards. */
+    val gold: List<GoldOwed> = emptyList(),
+)
+
+@Serializable
+data class GoldOwed(val seat: Int, val count: Int)
+
+/** Build a ship on [edge]: 1 lumber and 1 wool, on a sea edge joined to your fleet or a harbour town. */
+@Serializable
+@SerialName("ship")
+data class BuildShip(val edge: Int) : CatanMove
+
+/** Sail the ship on [from] to [to]: once a turn, never the turn it was built, only from the open end of a route. */
+@Serializable
+@SerialName("moveShip")
+data class MoveShip(val from: Int, val to: Int) : CatanMove
+
+/** Move the pirate to the sea hex [hex] and rob [victim], a seat with a ship beside it, if there is one. */
+@Serializable
+@SerialName("pirate")
+data class MovePirate(val hex: HexCoord, val victim: Int? = null) : CatanMove
+
+/** Choose the [cards] a gold field paid. */
+@Serializable
+@SerialName("gold")
+data class PickGold(val cards: List<Resource>) : CatanMove

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

@@ -54,7 +54,12 @@ object CatanRules : GameRules<CatanState, CatanMove> {
             "Seat count ${config.seats.size} does not match ${options.playerCount} players"
         }
 
-        val board = CatanBoard.generate(config.seed)
+        val sea = options.ruleSet == CatanRuleSet.SEAFARERS
+        val scenario = SeaScenario.NEW_SHORES
+        val seaBoard = if (sea) SeaBoards.generate(scenario, config.seed) else null
+        val topo = if (seaBoard != null) SeaBoards.topology(scenario) else CatanBoard.base
+        val board = seaBoard?.let { CatanBoard.Generated(it.terrains, it.numbers, it.robber, it.ports) }
+            ?: 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 ck = options.ruleSet == CatanRuleSet.CITIES_AND_KNIGHTS
@@ -79,8 +84,8 @@ object CatanRules : GameRules<CatanState, CatanMove> {
             numbers = board.numbers,
             robber = board.robber,
             ports = board.ports,
-            buildings = List(CatanBoard.VERTEX_COUNT) { null },
-            roads = List(CatanBoard.EDGE_COUNT) { NO_PLAYER },
+            buildings = List(topo.VERTEX_COUNT) { null },
+            roads = List(topo.EDGE_COUNT) { NO_PLAYER },
             resources = List(options.playerCount) {
                 Resource.entries.associateWith { 0 }
             },
@@ -98,10 +103,19 @@ object CatanRules : GameRules<CatanState, CatanMove> {
             rngStep = 0,
             winner = null,
             log = listOf(
-                "Catan${if (ck) " — Cities & Knights" else ""} — ${options.playerCount} players, " +
+                "Catan${if (ck) " — Cities & Knights" else if (sea) " — Seafarers: ${scenario.title}" else ""} — ${options.playerCount} players, " +
                     "first to ${options.pointsToWin} victory points.",
             ),
             ck = if (ck) CatanCk.initial(options, config.seed) else null,
+            sea = seaBoard?.let {
+                SeaState(
+                    scenario = scenario,
+                    ships = List(topo.EDGE_COUNT) { NO_PLAYER },
+                    pirate = it.pirate,
+                    islandBonus = List(topo.islandCount) { NO_PLAYER },
+                    home = it.home,
+                )
+            },
         )
     }
 
@@ -114,6 +128,7 @@ object CatanRules : GameRules<CatanState, CatanMove> {
             ?: state.ck?.goodsOffer?.asking?.takeIf { it >= 0 }
         CatanPhase.TRADE_COUNTERS -> state.turn
         CatanPhase.CHORE -> state.ck?.chores?.firstOrNull()?.seat
+        CatanPhase.GOLD -> state.sea?.gold?.firstOrNull()?.seat
         CatanPhase.AWAIT_ROLL, CatanPhase.ROBBER,
         CatanPhase.PLAYING, CatanPhase.FREE_ROADS,
         -> state.turn
@@ -162,12 +177,17 @@ object CatanRules : GameRules<CatanState, CatanMove> {
 
             CatanPhase.DISCARDING -> discardMoves(state, seat)
 
-            CatanPhase.ROBBER -> robberMoves(state, seat)
+            CatanPhase.ROBBER -> robberMoves(state, seat) +
+                (if (state.isSea) SeaRules.pirateMoves(state, seat) else emptyList())
 
             CatanPhase.PLAYING -> playingMoves(state, seat)
 
             CatanPhase.FREE_ROADS ->
-                roadMoves(state, seat) + listOf<CatanMove>(EndFreeRoads)
+                roadMoves(state, seat) +
+                    (if (state.isSea) SeaRules.buildShipMoves(state, seat) else emptyList()) +
+                    listOf<CatanMove>(EndFreeRoads)
+
+            CatanPhase.GOLD -> SeaRules.goldMoves(state)
 
             CatanPhase.TRADE_PENDING -> tradeResponses(state, seat)
 
@@ -179,10 +199,12 @@ object CatanRules : GameRules<CatanState, CatanMove> {
 
     internal fun setupMoves(state: CatanState): List<SetupPlace> {
         val moves = mutableListOf<SetupPlace>()
-        for (v in 0 until CatanBoard.VERTEX_COUNT) {
+        for (v in 0 until state.topo.VERTEX_COUNT) {
             if (!vertexOpenForSettlement(state, v)) continue
-            for (e in CatanBoard.VERTEX_EDGES[v]) {
-                if (state.roads[e] != NO_PLAYER) continue
+            // Seafarers: everyone starts on the home island.
+            if (state.sea != null && state.topo.vertexIsland[v] != state.sea.home) continue
+            for (e in state.topo.VERTEX_EDGES[v]) {
+                if (state.roads[e] != NO_PLAYER || !state.topo.edgeLand[e]) continue
                 moves += SetupPlace(v, e)
             }
         }
@@ -215,18 +237,18 @@ object CatanRules : GameRules<CatanState, CatanMove> {
 
     private fun robberMoves(state: CatanState, seat: Int): List<MoveRobber> {
         val moves = mutableListOf<MoveRobber>()
-        for (h in 0 until CatanBoard.HEX_COUNT) {
-            if (h == state.robber) continue
-            val victims = CatanBoard.HEX_CORNERS[h]
+        for (h in 0 until state.topo.HEX_COUNT) {
+            if (h == state.robber || !state.topo.land[h]) continue
+            val victims = state.topo.HEX_CORNERS[h]
                 .mapNotNull { state.buildings[it] }
                 .map { it.owner }
                 .filter { it != seat }
                 .distinct()
                 .filter { state.resourceCount(it) > 0 }
             if (victims.isEmpty()) {
-                moves += MoveRobber(CatanBoard.HEXES[h])
+                moves += MoveRobber(state.topo.HEXES[h])
             } else {
-                victims.forEach { moves += MoveRobber(CatanBoard.HEXES[h], it) }
+                victims.forEach { moves += MoveRobber(state.topo.HEXES[h], it) }
             }
         }
         return moves
@@ -245,6 +267,10 @@ object CatanRules : GameRules<CatanState, CatanMove> {
         if (state.devDeck.isNotEmpty() && affordable(state, seat, DEV_COST)) {
             moves += BuyDevCard
         }
+        if (state.isSea) {
+            if (affordable(state, seat, SeaRules.SHIP_COST)) moves += SeaRules.buildShipMoves(state, seat)
+            moves += SeaRules.moveShipMoves(state, seat)
+        }
 
         if (!state.devCardPlayedThisTurn) {
             for (card in state.devHands[seat]) {
@@ -301,8 +327,12 @@ object CatanRules : GameRules<CatanState, CatanMove> {
         if (state.roads.count { it == seat } >= MAX_ROADS) {
             emptyList()
         } else {
-            (0 until CatanBoard.EDGE_COUNT)
-                .filter { state.roads[it] == NO_PLAYER && roadConnects(state, seat, it) }
+            (0 until state.topo.EDGE_COUNT)
+                .filter {
+                    state.roads[it] == NO_PLAYER && state.topo.edgeLand[it] &&
+                        state.sea?.ships?.get(it).let { ship -> ship == null || ship == NO_PLAYER } &&
+                        roadConnects(state, seat, it)
+                }
                 .map { BuildRoad(it) }
         }
 
@@ -316,9 +346,9 @@ object CatanRules : GameRules<CatanState, CatanMove> {
         if (piecesOf(state, seat, BuildingType.SETTLEMENT) >= MAX_SETTLEMENTS) {
             emptyList()
         } else {
-            (0 until CatanBoard.VERTEX_COUNT).filter { v ->
+            (0 until state.topo.VERTEX_COUNT).filter { v ->
                 vertexOpenForSettlement(state, v) &&
-                    CatanBoard.VERTEX_EDGES[v].any { state.roads[it] == seat }
+                    state.topo.VERTEX_EDGES[v].any { state.roads[it] == seat || state.sea?.ships?.get(it) == seat }
             }
         }
 
@@ -326,7 +356,7 @@ object CatanRules : GameRules<CatanState, CatanMove> {
         if (piecesOf(state, seat, BuildingType.CITY) >= MAX_CITIES) {
             emptyList()
         } else {
-            (0 until CatanBoard.VERTEX_COUNT).filter { v ->
+            (0 until state.topo.VERTEX_COUNT).filter { v ->
                 state.buildings[v] == CatanBuilding(BuildingType.SETTLEMENT, seat)
             }
         }
@@ -373,8 +403,8 @@ object CatanRules : GameRules<CatanState, CatanMove> {
 
     /** An empty vertex with no building on it or one edge away. */
     internal fun vertexOpenForSettlement(state: CatanState, v: Int): Boolean =
-        state.buildings[v] == null && !hasKnight(state, v) &&
-            CatanBoard.VERTEX_NEIGHBORS[v].all { state.buildings[it] == null }
+        state.buildings[v] == null && !hasKnight(state, v) && state.topo.vertexLand[v] &&
+            state.topo.VERTEX_NEIGHBORS[v].all { state.buildings[it] == null }
 
     /**
      * A road on [edge] would join [seat]'s network of roads and buildings.
@@ -385,7 +415,7 @@ object CatanRules : GameRules<CatanState, CatanMove> {
      * of your own roads ending at the same crossing.
      */
     private fun roadConnects(state: CatanState, seat: Int, edge: Int): Boolean {
-        val (a, b) = CatanBoard.EDGE_VERTICES[edge]
+        val (a, b) = state.topo.EDGE_VERTICES[edge]
         return networkReaches(state, seat, a) || networkReaches(state, seat, b)
     }
 
@@ -397,7 +427,7 @@ object CatanRules : GameRules<CatanState, CatanMove> {
         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 }
+        return state.topo.VERTEX_EDGES[vertex].any { state.roads[it] == seat }
     }
 
     private fun offerLegal(state: CatanState, seat: Int, move: OfferTrade): Boolean {
@@ -423,6 +453,10 @@ object CatanRules : GameRules<CatanState, CatanMove> {
             is RollDice -> applyRoll(state, seat, move)
             is Discard -> applyDiscard(state, seat, move)
             is MoveRobber -> applyRobber(state, seat, move)
+            is BuildShip -> applyBuildShip(state, seat, move)
+            is MoveShip -> applyMoveShip(state, seat, move)
+            is MovePirate -> applyMovePirate(state, seat, move)
+            is PickGold -> applyPickGold(state, seat, move)
             is BuildRoad -> applyBuildRoad(state, seat, move)
             is BuildSettlement -> applyBuildSettlement(state, seat, move)
             is BuildCity -> applyBuildCity(state, seat, move)
@@ -461,7 +495,7 @@ object CatanRules : GameRules<CatanState, CatanMove> {
         if (second) {
             // The second settlement earns one card from each adjacent
             // producing hex, supply permitting.
-            val adjacent = CatanBoard.VERTEX_HEXES[move.vertex].mapNotNull { state.terrains[it].produces }
+            val adjacent = state.topo.VERTEX_HEXES[move.vertex].mapNotNull { state.terrains[it].produces }
             val granted = adjacent.groupingBy { it }.eachCount().filter { (res, need) ->
                 need <= bankSupply(state, res)
             }
@@ -517,11 +551,11 @@ object CatanRules : GameRules<CatanState, CatanMove> {
         val gains = List(state.playerCount) { mutableMapOf<Resource, Int>() }
         for (resource in Resource.entries) {
             var demand = 0
-            for (h in 0 until CatanBoard.HEX_COUNT) {
+            for (h in 0 until state.topo.HEX_COUNT) {
                 if (state.numbers[h] != number) continue
                 if (h == state.robber) continue
                 if (state.terrains[h].produces != resource) continue
-                for (v in CatanBoard.HEX_CORNERS[h]) {
+                for (v in state.topo.HEX_CORNERS[h]) {
                     val building = state.buildings[v] ?: continue
                     val amount = if (building.type == BuildingType.CITY) 2 else 1
                     gains[building.owner][resource] = (gains[building.owner][resource] ?: 0) + amount
@@ -535,6 +569,9 @@ object CatanRules : GameRules<CatanState, CatanMove> {
             }
         }
 
+        // Seafarers: gold fields pay a card of the owner's choice, asked for after the rest is dealt.
+        val goldOwed = if (state.isSea) goldOwed(state, number) else emptyList()
+
         var s = state.copy(phase = CatanPhase.PLAYING)
         val whoGot = mutableListOf<String>()
         for (seat in 0 until s.playerCount) {
@@ -543,10 +580,31 @@ object CatanRules : GameRules<CatanState, CatanMove> {
             s = s.copy(resources = withCounts(s.resources, seat, got, 1))
             whoGot += "seat $seat takes ${describe(got)}"
         }
-        val said = if (whoGot.isEmpty()) "nothing for anyone" else whoGot.joinToString(", ")
-        return s.copy(
+        val goldLine = goldOwed.joinToString("") { ", seat ${it.seat} is owed ${it.count} gold" }
+        val said = if (whoGot.isEmpty() && goldOwed.isEmpty()) "nothing for anyone" else
+            (whoGot.joinToString(", ") + goldLine).trimStart(',', ' ')
+        s = s.copy(
             log = s.log + "Seat ${state.turn} rolls ${state.lastDice.joinToString(" + ")} — $said.",
         )
+        if (goldOwed.isEmpty()) return s
+        return SeaRules.settleGold(s.copy(sea = s.sea!!.copy(gold = goldOwed)))
+    }
+
+    /** What each seat is owed for gold fields showing [number], in seat order from the roller. */
+    private fun goldOwed(state: CatanState, number: Int): List<GoldOwed> {
+        val topo = state.topo
+        val owed = IntArray(state.playerCount)
+        for (h in 0 until topo.HEX_COUNT) {
+            if (state.terrains[h] != Terrain.GOLD || state.numbers[h] != number || h == state.robber) continue
+            for (v in topo.HEX_CORNERS[h]) {
+                val building = state.buildings[v] ?: continue
+                owed[building.owner] += if (building.type == BuildingType.CITY) 2 else 1
+            }
+        }
+        return (0 until state.playerCount)
+            .map { (state.turn + it) % state.playerCount }
+            .filter { owed[it] > 0 }
+            .map { GoldOwed(it, owed[it]) }
     }
 
     private fun applyDiscard(state: CatanState, seat: Int, move: Discard): CatanState {
@@ -565,7 +623,7 @@ object CatanRules : GameRules<CatanState, CatanMove> {
 
     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]
+        val hex = state.topo.hexIndex[move.hex]
             ?: throw IllegalArgumentException("No hex at ${move.hex}")
         var s = state.copy(robber = hex, rngStep = state.rngStep + 1)
         var stolen: String? = null
@@ -599,6 +657,68 @@ object CatanRules : GameRules<CatanState, CatanMove> {
         return checkWin(s.copy(log = s.log + "Seat $seat builds a road on ${move.edge}."))
     }
 
+    private fun applyBuildShip(state: CatanState, seat: Int, move: BuildShip): CatanState {
+        val free = state.phase == CatanPhase.FREE_ROADS
+        val sea = state.sea!!
+        var s = state.copy(
+            sea = sea.copy(
+                ships = sea.ships.toMutableList().also { it[move.edge] = seat },
+                builtThisTurn = sea.builtThisTurn + move.edge,
+            ),
+        )
+        if (!free) s = payCost(s, seat, SeaRules.SHIP_COST)
+        s = refreshLongestRoad(s)
+        if (free) {
+            val left = s.pendingFreeRoads - 1
+            s = s.copy(pendingFreeRoads = left)
+            if (left == 0) s = s.copy(phase = phaseAfterRoads(s))
+        }
+        return checkWin(s.copy(log = s.log + "Seat $seat launches a ship on ${move.edge}."))
+    }
+
+    private fun applyMoveShip(state: CatanState, seat: Int, move: MoveShip): CatanState {
+        val sea = state.sea!!
+        val ships = sea.ships.toMutableList().also {
+            it[move.from] = NO_PLAYER
+            it[move.to] = seat
+        }
+        // The ship is on a new edge, but it has sailed for the turn and may not sail again.
+        val s = state.copy(
+            sea = sea.copy(ships = ships, shipMoved = true, builtThisTurn = sea.builtThisTurn + move.to),
+        )
+        return checkWin(refreshLongestRoad(s).let {
+            it.copy(log = it.log + "Seat $seat sails a ship from ${move.from} to ${move.to}.")
+        })
+    }
+
+    private fun applyMovePirate(state: CatanState, seat: Int, move: MovePirate): CatanState {
+        val hex = state.topo.hexIndex[move.hex] ?: throw IllegalArgumentException("No hex at ${move.hex}")
+        var s = state.copy(sea = state.sea!!.copy(pirate = hex), rngStep = state.rngStep + 1)
+        var stolen = ""
+        if (move.victim != null) {
+            val rng = Random(state.seed * 1_000_003L + state.rngStep)
+            val victimHand = state.handOf(move.victim)
+            val card = victimHand[rng.nextInt(victimHand.size)]
+            val less = withCards(s.resources, move.victim, listOf(card), -1)
+            s = s.copy(resources = withCards(less, seat, listOf(card), 1))
+            stolen = " and takes a ${card.name.lowercase()} from seat ${move.victim}"
+        }
+        return s.copy(
+            phase = CatanPhase.PLAYING,
+            log = s.log + "Seat $seat sends the pirate to (${move.hex.q},${move.hex.r})$stolen.",
+        )
+    }
+
+    private fun applyPickGold(state: CatanState, seat: Int, move: PickGold): CatanState {
+        val sea = state.sea!!
+        val s = state.copy(
+            resources = withCards(state.resources, seat, move.cards, 1),
+            sea = sea.copy(gold = sea.gold.drop(1)),
+            log = state.log + "Seat $seat takes ${describe(countOf(move.cards))} from the gold.",
+        )
+        return SeaRules.settleGold(s)
+    }
+
     private fun applyBuildSettlement(state: CatanState, seat: Int, move: BuildSettlement): CatanState {
         var s = state.copy(
             buildings = state.buildings.toMutableList().also {
@@ -606,6 +726,7 @@ object CatanRules : GameRules<CatanState, CatanMove> {
             },
         )
         s = payCost(s, seat, SETTLEMENT_COST)
+        s = SeaRules.claimIsland(s, seat, move.vertex)
         // A settlement can break another player's road, so the award is
         // recomputed for everyone.
         s = refreshLongestRoad(s)
@@ -831,6 +952,7 @@ object CatanRules : GameRules<CatanState, CatanMove> {
             phase = CatanPhase.AWAIT_ROLL,
             devCardPlayedThisTurn = false,
             pendingTrade = null,
+            sea = state.sea?.copy(builtThisTurn = emptyList(), shipMoved = false),
         )
         // Someone can cross the target on another player's turn (a broken
         // Longest Road re-awarded to a third player); they win when their
@@ -869,6 +991,7 @@ object CatanRules : GameRules<CatanState, CatanMove> {
         }
         state.longestRoadOwner?.let { points[it] += 5 }
         state.largestArmyOwner?.let { points[it] += 5 }
+        if (state.isSea) for (seat in points.indices) points[seat] += SeaRules.bonusPoints(state, seat)
         return points.toList()
     }
 
@@ -927,16 +1050,17 @@ object CatanRules : GameRules<CatanState, CatanMove> {
      * one road, not two — the intersection is a branch).
      */
     fun longestRoadFor(state: CatanState, seat: Int): Int {
+        if (state.isSea) return SeaRules.longestRouteFor(state, seat)
         var best = 0
-        val blocked = BooleanArray(CatanBoard.VERTEX_COUNT)
-        for (v in 0 until CatanBoard.VERTEX_COUNT) {
+        val blocked = BooleanArray(state.topo.VERTEX_COUNT)
+        for (v in 0 until state.topo.VERTEX_COUNT) {
             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)
+        for (start in 0 until state.topo.VERTEX_COUNT) {
+            if (state.topo.VERTEX_EDGES[start].none { state.roads[it] == seat }) continue
+            val visited = BooleanArray(state.topo.VERTEX_COUNT)
             best = maxOf(best, roadDfs(state, seat, start, blocked, visited))
         }
         return best
@@ -951,9 +1075,9 @@ object CatanRules : GameRules<CatanState, CatanMove> {
     ): Int {
         visited[v] = true
         var best = 0
-        for (e in CatanBoard.VERTEX_EDGES[v]) {
+        for (e in state.topo.VERTEX_EDGES[v]) {
             if (state.roads[e] != seat) continue
-            val w = CatanBoard.otherEnd(e, v)
+            val w = state.topo.otherEnd(e, v)
             if (visited[w]) continue
             if (blocked[w]) {
                 // The segment may run up to an opponent's building, but not
@@ -1039,7 +1163,7 @@ object CatanRules : GameRules<CatanState, CatanMove> {
         for (port in state.ports) {
             if (port.resource != null && port.resource != give) continue
             if (port.ratio >= best) continue
-            val (a, b) = CatanBoard.EDGE_VERTICES[port.edge]
+            val (a, b) = state.topo.EDGE_VERTICES[port.edge]
             val mine = state.buildings[a]?.owner == seat || state.buildings[b]?.owner == seat
             if (mine) best = port.ratio
         }
@@ -1050,7 +1174,7 @@ object CatanRules : GameRules<CatanState, CatanMove> {
     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]
+            val (a, b) = state.topo.EDGE_VERTICES[port.edge]
             if (state.buildings[a]?.owner == seat || state.buildings[b]?.owner == seat) return port.ratio
         }
         return 4

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

@@ -0,0 +1,144 @@
+package org.prolibertate.games.game.catan
+
+import kotlinx.serialization.Serializable
+import kotlin.random.Random
+
+/** The Seafarers maps on offer. Each is a fixed arrangement of land and sea; the tiles and numbers on it are shuffled. */
+@Serializable
+enum class SeaScenario(val title: String, val blurb: String) {
+    NEW_SHORES(
+        "Heading for New Shores",
+        "One large home island and three small ones to find by ship. Gold fields on two of the small islands.",
+    ),
+}
+
+/**
+ * The Seafarers maps as geometry plus a generator for one game's tiles.
+ *
+ * A map is drawn below as text: `.` is sea, `#` a land hex that gets a random resource,
+ * `$` a gold field, `D` the desert. Odd rows are shifted half a hex to the right (the usual
+ * "odd-r" offset layout). The outermost ring is always sea, so every coast is closed.
+ */
+object SeaBoards {
+
+    private val NEW_SHORES_MAP = listOf(
+        "..........",
+        "...##.....",
+        "..####.$#.",
+        ".#####..#.",
+        ".##D###...",
+        "..####..#.",
+        ".......##.",
+        ".$#.......",
+        "..........",
+    )
+
+    private fun rows(scenario: SeaScenario): List<String> = when (scenario) {
+        SeaScenario.NEW_SHORES -> NEW_SHORES_MAP
+    }
+
+    private val topologies = HashMap<SeaScenario, Topology>()
+
+    /** The frame of [scenario]: every hex, with its land mask. Built once and shared. */
+    fun topology(scenario: SeaScenario): Topology = synchronized(topologies) {
+        topologies.getOrPut(scenario) { build(scenario) }
+    }
+
+    /** Hex (row, col) of the text map as an axial coordinate (odd-r offset). */
+    private fun coord(row: Int, col: Int): HexCoord = HexCoord(col - (row - (row and 1)) / 2, row)
+
+    private fun build(scenario: SeaScenario): Topology {
+        val map = rows(scenario)
+        val hexes = mutableListOf<HexCoord>()
+        val land = mutableListOf<Boolean>()
+        map.forEachIndexed { row, text ->
+            text.forEachIndexed { col, ch ->
+                hexes += coord(row, col)
+                land += ch != '.'
+            }
+        }
+        return Topology(hexes, land, standardFrame = false, harbours = 9)
+    }
+
+    /** Terrain kind the map asks of each hex: sea, gold, desert, or "pick a resource". */
+    private fun kinds(scenario: SeaScenario): List<Char> = rows(scenario).flatMap { it.toList() }
+
+    /** One game's tiles on a Seafarers map. */
+    @Serializable
+    data class Generated(
+        val terrains: List<Terrain>,
+        val numbers: List<Int>,
+        val robber: Int,
+        val pirate: Int,
+        val ports: List<Port>,
+        val home: Int,
+    )
+
+    private val RESOURCE_TILES = listOf(
+        Terrain.FOREST, Terrain.PASTURE, Terrain.FIELDS, Terrain.HILLS, Terrain.MOUNTAINS,
+    )
+
+    /** Number tokens: the standard 18 plus ten more, so every land hex but the desert has one. */
+    private val TOKENS = listOf(2, 3, 3, 4, 4, 5, 5, 6, 6, 8, 8, 9, 9, 10, 10, 11, 11, 12) +
+        listOf(3, 4, 5, 6, 8, 9, 10, 11, 5, 9)
+
+    fun generate(scenario: SeaScenario, seed: Long): Generated {
+        val topo = topology(scenario)
+        val kinds = kinds(scenario)
+        val random = Random(seed)
+
+        // Resources fill the '#' hexes as evenly as the count allows, in shuffled order.
+        val plain = kinds.indices.filter { kinds[it] == '#' }
+        val pool = List(plain.size) { RESOURCE_TILES[it % RESOURCE_TILES.size] }.shuffled(random)
+        val terrains = MutableList(kinds.size) { Terrain.SEA }
+        kinds.forEachIndexed { h, ch ->
+            terrains[h] = when (ch) {
+                '$' -> Terrain.GOLD
+                'D' -> Terrain.DESERT
+                '#' -> pool[plain.indexOf(h)]
+                else -> Terrain.SEA
+            }
+        }
+
+        val numbered = terrains.indices.filter { terrains[it] != Terrain.SEA && terrains[it] != Terrain.DESERT }
+        check(numbered.size <= TOKENS.size) { "Not enough number tokens for ${numbered.size} hexes" }
+        val tokens = TOKENS.take(numbered.size).shuffled(random)
+        val numbers = IntArray(terrains.size)
+        var placed = false
+        var attempt = 0
+        while (!placed && attempt < 200) {
+            val order = numbered.shuffled(random)
+            val assigned = IntArray(terrains.size)
+            order.forEachIndexed { i, h -> assigned[h] = tokens[i] }
+            val reds = numbered.filter { assigned[it] == 6 || assigned[it] == 8 }
+            val clash = reds.any { a -> reds.any { b -> a < b && topo.hexesAdjacent(a, b) } }
+            if (!clash || attempt == 199) {
+                assigned.copyInto(numbers)
+                placed = true
+            }
+            attempt++
+        }
+
+        val portTypes = (
+            listOf(Resource.LUMBER, Resource.BRICK, Resource.WOOL, Resource.GRAIN, Resource.ORE) + List(4) { null }
+            ).shuffled(random)
+        val ports = topo.PORT_POSITIONS.mapIndexed { i, edge ->
+            val resource = portTypes[i % portTypes.size]
+            if (resource == null) Port(edge, null, 3) else Port(edge, resource, 2)
+        }
+
+        val desert = terrains.indexOf(Terrain.DESERT).takeIf { it >= 0 }
+            ?: numbered.first()
+        val home = (0 until topo.islandCount).maxByOrNull { island -> topo.islandOf.count { it == island } } ?: 0
+        // The pirate starts in the open sea: the sea hex farthest from every shore.
+        val sea = terrains.indices.filter { terrains[it] == Terrain.SEA }
+        val pirate = sea.maxByOrNull { h ->
+            val c = topo.HEXES[h]
+            terrains.indices.filter { terrains[it] != Terrain.SEA }.minOfOrNull {
+                Topology.hexDistance(c.q, c.r, topo.HEXES[it].q, topo.HEXES[it].r)
+            } ?: 0
+        } ?: sea.first()
+
+        return Generated(terrains, numbers.toList(), desert, pirate, ports, home)
+    }
+}

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

@@ -0,0 +1,205 @@
+package org.prolibertate.games.game.catan
+
+/**
+ * The rules Seafarers adds to the base game, kept apart from [CatanRules] so the base
+ * game's code reads as it always did. [CatanRules] calls in here only when a game has
+ * [CatanState.sea]. See `docs/RULES-catan-seafarers.md`.
+ */
+internal object SeaRules {
+
+    const val MAX_SHIPS = 15
+
+    /** Points for being the first to settle an island other than the home island. */
+    const val ISLAND_BONUS = 2
+
+    val SHIP_COST: Map<Resource, Int> = mapOf(Resource.LUMBER to 1, Resource.WOOL to 1)
+
+    // -----------------------------------------------------------------------
+    // Ships
+    // -----------------------------------------------------------------------
+
+    private fun fleetOf(state: CatanState, seat: Int): Int = state.sea!!.ships.count { it == seat }
+
+    /**
+     * Whether [seat]'s ships and towns reach [vertex], so a ship may start there. A town
+     * of anyone else is a wall; [ignoring] is a ship that is being lifted off the board.
+     */
+    private fun shipReaches(state: CatanState, seat: Int, vertex: Int, ignoring: Int): Boolean {
+        val building = state.buildings[vertex]
+        if (building != null) return building.owner == seat
+        val sea = state.sea!!
+        return state.topo.VERTEX_EDGES[vertex].any { it != ignoring && sea.ships[it] == seat }
+    }
+
+    /** A sea edge a ship could sit on, joined to [seat]'s fleet or a town of theirs. */
+    private fun shipSites(state: CatanState, seat: Int, ignoring: Int = -1): List<Int> {
+        val topo = state.topo
+        val sea = state.sea!!
+        return (0 until topo.EDGE_COUNT).filter { e ->
+            topo.edgeSea[e] &&
+                state.roads[e] == NO_PLAYER &&
+                (sea.ships[e] == NO_PLAYER || e == ignoring) &&
+                sea.pirate !in topo.EDGE_HEXES[e] &&
+                topo.EDGE_VERTICES[e].let { (a, b) ->
+                    shipReaches(state, seat, a, ignoring) || shipReaches(state, seat, b, ignoring)
+                }
+        }
+    }
+
+    fun buildShipMoves(state: CatanState, seat: Int): List<BuildShip> =
+        if (fleetOf(state, seat) >= MAX_SHIPS) emptyList() else shipSites(state, seat).map { BuildShip(it) }
+
+    /** Whether the ship on [edge] sits at the open end of a route: one end touches nothing else of [seat]'s. */
+    private fun atOpenEnd(state: CatanState, seat: Int, edge: Int): Boolean {
+        val topo = state.topo
+        val sea = state.sea!!
+        return topo.EDGE_VERTICES[edge].toList().any { v ->
+            state.buildings[v] == null &&
+                topo.VERTEX_EDGES[v].none { it != edge && (state.roads[it] == seat || sea.ships[it] == seat) }
+        }
+    }
+
+    /** A ship may sail once a turn, never the turn it was built, only from the open end of a route. */
+    fun moveShipMoves(state: CatanState, seat: Int): List<MoveShip> {
+        val sea = state.sea!!
+        if (sea.shipMoved) return emptyList()
+        val moves = mutableListOf<MoveShip>()
+        for (e in sea.ships.indices) {
+            if (sea.ships[e] != seat || e in sea.builtThisTurn || !atOpenEnd(state, seat, e)) continue
+            shipSites(state, seat, ignoring = e).filter { it != e }.forEach { moves += MoveShip(e, it) }
+        }
+        return moves
+    }
+
+    // -----------------------------------------------------------------------
+    // Pirate
+    // -----------------------------------------------------------------------
+
+    /** Seats with a ship beside [hex] that hold at least one card: whom the pirate can rob there. */
+    private fun pirateVictims(state: CatanState, thief: Int, hex: Int): List<Int> {
+        val topo = state.topo
+        val sea = state.sea!!
+        return (0 until topo.EDGE_COUNT).filter { hex in topo.EDGE_HEXES[it] }
+            .map { sea.ships[it] }
+            .filter { it != NO_PLAYER && it != thief }
+            .distinct()
+            .filter { state.resourceCount(it) > 0 }
+    }
+
+    fun pirateMoves(state: CatanState, seat: Int): List<MovePirate> {
+        val topo = state.topo
+        val sea = state.sea!!
+        val moves = mutableListOf<MovePirate>()
+        for (h in 0 until topo.HEX_COUNT) {
+            if (topo.land[h] || h == sea.pirate) continue
+            val victims = pirateVictims(state, seat, h)
+            if (victims.isEmpty()) {
+                moves += MovePirate(topo.HEXES[h])
+            } else {
+                victims.forEach { moves += MovePirate(topo.HEXES[h], it) }
+            }
+        }
+        return moves
+    }
+
+    // -----------------------------------------------------------------------
+    // Gold
+    // -----------------------------------------------------------------------
+
+    /** Every way the seat at the front of the gold queue can choose its cards, supply permitting. */
+    fun goldMoves(state: CatanState): List<PickGold> {
+        val owed = state.sea!!.gold.firstOrNull() ?: return emptyList()
+        val supply = Resource.entries.associateWith { CatanRules.bankSupply(state, it) }
+        val take = minOf(owed.count, supply.values.sum())
+        val picks = mutableListOf<PickGold>()
+        fun walk(index: Int, left: Int, acc: MutableList<Resource>) {
+            if (left == 0) {
+                picks += PickGold(acc.toList())
+                return
+            }
+            if (index == Resource.entries.size) return
+            val resource = Resource.entries[index]
+            for (n in 0..minOf(left, supply.getValue(resource))) {
+                repeat(n) { acc += resource }
+                walk(index + 1, left - n, acc)
+                repeat(n) { acc.removeAt(acc.size - 1) }
+            }
+        }
+        walk(0, take, mutableListOf())
+        return picks
+    }
+
+    /** Drops queue entries the bank can no longer pay, and leaves the gold phase once nobody is owed. */
+    fun settleGold(state: CatanState): CatanState {
+        val sea = state.sea!!
+        val supply = Resource.entries.sumOf { CatanRules.bankSupply(state, it) }
+        val queue = if (supply > 0) sea.gold else emptyList()
+        return if (queue.isEmpty()) {
+            state.copy(sea = sea.copy(gold = emptyList()), phase = CatanPhase.PLAYING)
+        } else {
+            state.copy(sea = sea.copy(gold = queue), phase = CatanPhase.GOLD)
+        }
+    }
+
+    // -----------------------------------------------------------------------
+    // Islands and scoring
+    // -----------------------------------------------------------------------
+
+    /** The bonus points [seat] holds for first landings. */
+    fun bonusPoints(state: CatanState, seat: Int): Int =
+        (state.sea?.islandBonus?.count { it == seat } ?: 0) * ISLAND_BONUS
+
+    /** After a settlement on [vertex]: award the island bonus if it is the first on a new island. */
+    fun claimIsland(state: CatanState, seat: Int, vertex: Int): CatanState {
+        val sea = state.sea ?: return state
+        val island = state.topo.vertexIsland[vertex]
+        if (island < 0 || island == sea.home || sea.islandBonus[island] != NO_PLAYER) return state
+        val bonus = sea.islandBonus.toMutableList().also { it[island] = seat }
+        return state.copy(
+            sea = sea.copy(islandBonus = bonus),
+            log = state.log + "Seat $seat is the first to settle a new island: +$ISLAND_BONUS victory points.",
+        )
+    }
+
+    // -----------------------------------------------------------------------
+    // Longest route
+    // -----------------------------------------------------------------------
+
+    /**
+     * The seat's longest route over roads *and* ships. A route is a simple path of the seat's
+     * pieces that never runs through an opponent's town; it may change between road and ship
+     * only at a town of the seat's own.
+     */
+    fun longestRouteFor(state: CatanState, seat: Int): Int {
+        val topo = state.topo
+        val sea = state.sea!!
+        val blocked = BooleanArray(topo.VERTEX_COUNT) { v ->
+            state.buildings[v]?.let { it.owner != seat } == true
+        }
+        fun owns(e: Int) = state.roads[e] == seat || sea.ships[e] == seat
+        fun kind(e: Int) = if (state.roads[e] == seat) 0 else 1
+
+        fun walk(v: Int, arrivedBy: Int, visited: BooleanArray): Int {
+            visited[v] = true
+            var best = 0
+            val ownTown = state.buildings[v]?.owner == seat
+            for (e in topo.VERTEX_EDGES[v]) {
+                if (!owns(e)) continue
+                val k = kind(e)
+                if (arrivedBy != -1 && k != arrivedBy && !ownTown) continue
+                val w = topo.otherEnd(e, v)
+                if (visited[w]) continue
+                best = maxOf(best, if (blocked[w]) 1 else 1 + walk(w, k, visited))
+            }
+            visited[v] = false
+            return best
+        }
+
+        var best = 0
+        for (start in 0 until topo.VERTEX_COUNT) {
+            if (topo.VERTEX_EDGES[start].none { owns(it) }) continue
+            best = maxOf(best, walk(start, -1, BooleanArray(topo.VERTEX_COUNT)))
+        }
+        return best
+    }
+}

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
@@ -83,6 +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()) }
@@ -101,6 +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()) }
@@ -132,6 +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)
@@ -149,6 +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)
 
@@ -193,6 +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 }
@@ -233,6 +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),
@@ -341,12 +365,15 @@ internal fun catanPointsChoices(ruleSet: CatanRuleSet): List<Int> = when (ruleSe
     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)
+    // Seafarers adds two points for each new island, so the target is higher.
+    CatanRuleSet.SEAFARERS -> listOf(8, 10, 12, 14)
 }
 
 /** The published target for a rule set. */
 internal fun catanDefaultPoints(ruleSet: CatanRuleSet): Int = when (ruleSet) {
     CatanRuleSet.BASE -> 10
     CatanRuleSet.CITIES_AND_KNIGHTS -> 13
+    CatanRuleSet.SEAFARERS -> 12
 }
 
 /**
@@ -363,6 +390,7 @@ internal fun catanSwitchRules(options: CatanOptions, ruleSet: CatanRuleSet): Cat
 private fun catanRuleSetName(ruleSet: CatanRuleSet): String = when (ruleSet) {
     CatanRuleSet.BASE -> "Base game"
     CatanRuleSet.CITIES_AND_KNIGHTS -> "Cities & Knights"
+    CatanRuleSet.SEAFARERS -> "Seafarers"
 }
 
 private fun catanRuleSetBlurb(ruleSet: CatanRuleSet): String = when (ruleSet) {
@@ -371,6 +399,9 @@ private fun catanRuleSetBlurb(ruleSet: CatanRuleSet): String = when (ruleSet) {
     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."
+    CatanRuleSet.SEAFARERS ->
+        "Build ships to reach new islands. Gold fields pay any resource, a pirate guards the sea, " +
+            "and the first settlement on each new island scores two extra points."
 }
 
 @Composable
@@ -1116,6 +1147,36 @@ 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)) {
@@ -1216,3 +1277,30 @@ 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

@@ -33,6 +33,7 @@ import org.prolibertate.games.game.catan.CatanBoard
 import org.prolibertate.games.game.catan.CatanState
 import org.prolibertate.games.game.catan.NO_PLAYER
 import org.prolibertate.games.game.catan.Resource
+import org.prolibertate.games.game.catan.Terrain
 
 /**
  * The island, drawn and tappable.
@@ -61,12 +62,18 @@ fun CatanBoardView(
     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) }
-    val layout = remember(size) {
+    val topo = state.topo
+    val layout = remember(size, topo) {
         if (size.width > 0 && size.height > 0) {
-            CatanGeometry.fit(size.width.toFloat(), size.height.toFloat())
+            CatanGeometry.fit(size.width.toFloat(), size.height.toFloat(), topo)
         } else {
             null
         }
@@ -80,7 +87,7 @@ fun CatanBoardView(
 
     Canvas(
         modifier = modifier
-            .aspectRatio(CatanGeometry.ASPECT)
+            .aspectRatio(CatanGeometry.aspect(topo))
             .onSizeChanged { size = it }
             .semantics { contentDescription = "Katan island board" }
             .pointerInput(layout, targets, style) {
@@ -92,8 +99,8 @@ fun CatanBoardView(
                         targets.tappableVertices.isNotEmpty() ->
                             board.nearestVertex(at, reach, targets.tappableVertices)?.let { vertexTap(it) }
 
-                        targets.edges.isNotEmpty() ->
-                            board.nearestEdge(at, reach, targets.edges)?.let { edgeTap(it) }
+                        targets.edges.isNotEmpty() || targets.ships.isNotEmpty() ->
+                            board.nearestEdge(at, reach, targets.edges + targets.ships)?.let { edgeTap(it) }
 
                         targets.hexes.isNotEmpty() ->
                             // A hex is big: accept a tap anywhere near its middle.
@@ -108,9 +115,12 @@ fun CatanBoardView(
         drawHexes(state, board, style, measurer)
         drawRolled(rolledHexes, board, style)
         drawRobber(state, board, style)
+        drawPirate(state, board, style)
         drawMerchant(state, board, style, measurer)
         drawRoads(state, board, style)
+        drawShips(state, board, style)
         drawEdgeTargets(targets, board, style)
+        drawShipTargets(targets, board, style)
         drawBuildings(state, board, style)
         drawWalls(state, board, style)
         drawMetropolises(state, board, style)
@@ -118,6 +128,7 @@ fun CatanBoardView(
         drawKnightTargets(targets, board, style)
         drawVertexTargets(targets, selectedVertex ?: selectedKnight, board, style)
         drawHexTargets(targets, board, style)
+        drawStaged(stagedVertex, stagedEdge, stagedSeat, board, style)
     }
 }
 
@@ -131,10 +142,15 @@ private fun DrawScope.drawHexes(
     style: CatanStyle,
     measurer: TextMeasurer,
 ) {
-    for (hex in 0 until CatanBoard.HEX_COUNT) {
+    for (hex in 0 until state.topo.HEX_COUNT) {
         val centre = board.hexCenter(hex)
         val corners = board.hexCorners(hex).map { insetToward(it, centre, style.hexInset) }
         val path = polygon(corners)
+        if (state.terrains[hex] == Terrain.SEA) {
+            // Open water: only a faint outline, so ships have a grid to sail on.
+            drawPath(path, color = style.hexEdge.copy(alpha = 0.12f), style = Stroke(width = board.radius * 0.02f))
+            continue
+        }
         drawPath(path, color = style.terrain.getValue(state.terrains[hex]))
         drawPath(path, color = style.hexEdge, style = Stroke(width = board.radius * 0.03f))
 
@@ -359,7 +375,7 @@ private fun DrawScope.drawResourceIcon(resource: Resource, at: Pt, s: Float, fil
 // ---------------------------------------------------------------------------
 
 private fun DrawScope.drawRoads(state: CatanState, board: BoardLayout, style: CatanStyle) {
-    for (edge in 0 until CatanBoard.EDGE_COUNT) {
+    for (edge in 0 until state.topo.EDGE_COUNT) {
         val owner = state.roads[edge]
         if (owner == NO_PLAYER) continue
         val (a, b) = board.edgeEnds(edge)
@@ -385,7 +401,7 @@ private fun DrawScope.drawRoads(state: CatanState, board: BoardLayout, style: Ca
 }
 
 private fun DrawScope.drawBuildings(state: CatanState, board: BoardLayout, style: CatanStyle) {
-    for (vertex in 0 until CatanBoard.VERTEX_COUNT) {
+    for (vertex in 0 until state.topo.VERTEX_COUNT) {
         val building = state.buildings[vertex] ?: continue
         val at = board.vertex(vertex)
         val fill = style.seats[building.owner % style.seats.size]
@@ -642,3 +658,86 @@ 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))
+    }
+}
+
+// ---------------------------------------------------------------------------
+// Seafarers: ships, the pirate
+// ---------------------------------------------------------------------------
+
+/** A ship on each sea edge that has one: a hull along the edge with a sail amidships, in the owner's colour. */
+private fun DrawScope.drawShips(state: CatanState, board: BoardLayout, style: CatanStyle) {
+    val sea = state.sea ?: return
+    for (edge in sea.ships.indices) {
+        val owner = sea.ships[edge]
+        if (owner == NO_PLAYER) continue
+        val (a, b) = board.edgeEnds(edge)
+        val from = lerp(a, b, 0.2f)
+        val to = lerp(a, b, 0.8f)
+        val width = board.radius * style.roadWidth * 1.15f
+        val colour = style.seats[owner % style.seats.size]
+        drawLine(style.pieceOutline, from.offset(), to.offset(), width * 1.5f, StrokeCap.Round)
+        drawLine(colour, from.offset(), to.offset(), width, StrokeCap.Round)
+        // The sail: a small triangle standing off the hull, on the screen's upper side.
+        val mid = lerp(a, b, 0.5f)
+        val s = board.radius * 0.17f
+        val sail = Path().apply {
+            moveTo(mid.x - s * 0.1f, mid.y - s * 1.9f)
+            lineTo(mid.x + s * 1.1f, mid.y - s * 0.2f)
+            lineTo(mid.x - s * 0.1f, mid.y - s * 0.2f)
+            close()
+        }
+        drawPath(sail, style.shipSail)
+        drawPath(sail, style.pieceOutline, style = Stroke(width = board.radius * 0.03f))
+    }
+}
+
+/** A ring round each of the player's ships that can sail, so they read as tappable. */
+private fun DrawScope.drawShipTargets(targets: BoardTargets, board: BoardLayout, style: CatanStyle) {
+    for (edge in targets.ships) {
+        val mid = board.edgeMidpoint(edge).offset()
+        drawCircle(style.target, board.radius * 0.38f, mid, style = Stroke(width = board.radius * 0.07f))
+    }
+}
+
+/** The pirate: a black pawn with a flag, drawn beside the middle of its sea hex like the robber. */
+private fun DrawScope.drawPirate(state: CatanState, board: BoardLayout, style: CatanStyle) {
+    val sea = state.sea ?: return
+    val hex = board.hexCenter(sea.pirate)
+    val x = hex.x
+    val y = hex.y + board.radius * 0.1f
+    val s = board.radius * style.robberSize
+    val hull = Path().apply {
+        moveTo(x - s * 1.0f, y)
+        lineTo(x + s * 1.0f, y)
+        lineTo(x + s * 0.6f, y + s * 0.7f)
+        lineTo(x - s * 0.6f, y + s * 0.7f)
+        close()
+    }
+    drawPath(hull, style.pirate)
+    drawLine(style.pirate, Offset(x, y), Offset(x, y - s * 1.5f), strokeWidth = s * 0.12f)
+    val flag = Path().apply {
+        moveTo(x, y - s * 1.5f)
+        lineTo(x + s * 0.9f, y - s * 1.15f)
+        lineTo(x, y - s * 0.8f)
+        close()
+    }
+    drawPath(flag, style.pirate)
+    drawPath(hull, Color.White.copy(alpha = 0.7f), style = Stroke(width = s * 0.07f))
+}

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
@@ -137,6 +138,55 @@ fun CatanDiscardDialog(
     )
 }
 
+// ---------------------------------------------------------------------------
+// Gold (Seafarers)
+// ---------------------------------------------------------------------------
+
+/**
+ * A gold field paid out: choose the resource cards it gives. Not dismissable: the game
+ * is waiting. The engine's list says which resources the bank can still pay.
+ */
+@OptIn(ExperimentalLayoutApi::class)
+@Composable
+fun CatanGoldDialog(
+    legal: List<CatanMove>,
+    onSubmit: (org.prolibertate.games.game.catan.PickGold) -> Unit,
+) {
+    val count = CatanInteraction.goldCount(legal)
+    var picked by remember { mutableStateOf(emptyMap<Resource, Int>()) }
+    val selection = picked.asCards()
+    val move = CatanInteraction.goldMove(legal, selection)
+    // A resource is on offer if some legal pick names it.
+    val offered = legal.filterIsInstance<org.prolibertate.games.game.catan.PickGold>()
+        .flatMap { it.cards }.toSet()
+
+    AlertDialog(
+        onDismissRequest = {},
+        title = { Text(CatanText.GOLD_TITLE) },
+        text = {
+            Column(verticalArrangement = Arrangement.spacedBy(12.dp)) {
+                Text("Gold! Choose $count resource cards (${selection.size} of $count chosen).")
+                FlowRow(
+                    horizontalArrangement = Arrangement.spacedBy(8.dp),
+                    verticalArrangement = Arrangement.spacedBy(8.dp),
+                ) {
+                    Resource.entries.filter { it in offered }.forEach { resource ->
+                        ResourceCounter(
+                            resource = resource,
+                            count = picked[resource] ?: 0,
+                            max = if (selection.size < count) count else (picked[resource] ?: 0),
+                            onChange = { n -> picked = picked + (resource to n.coerceIn(0, count)) },
+                        )
+                    }
+                }
+            }
+        },
+        confirmButton = {
+            Button(onClick = { move?.let(onSubmit) }, enabled = move != null) { Text(CatanText.GOLD_TAKE) }
+        },
+    )
+}
+
 // ---------------------------------------------------------------------------
 // The robber
 // ---------------------------------------------------------------------------
@@ -603,7 +653,12 @@ 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/CatanGeometry.kt

@@ -1,6 +1,7 @@
 package org.prolibertate.games.ui.game.catan
 
 import org.prolibertate.games.game.catan.CatanBoard
+import org.prolibertate.games.game.catan.Topology
 import kotlin.math.sqrt
 
 /** A point in board pixels. Plain floats, so this file needs no Compose types. */
@@ -24,29 +25,35 @@ class BoardLayout(
     val height: Float,
     /** Circumradius of one hex, in pixels. */
     val radius: Float,
+    /** The board this layout draws: the standard island unless the game is Seafarers. */
+    val topo: Topology = CatanBoard.base,
 ) {
     private val centreX = width / 2f
     private val centreY = height / 2f
     private val unitX = radius * SQRT3 / 2f
     private val unitY = radius / 2f
 
+    /** The lattice point drawn at the middle of the box: the middle of the frame. */
+    private val midX = (topo.lattice[0] + topo.lattice[1]) / 2f
+    private val midY = (topo.lattice[2] + topo.lattice[3]) / 2f
+
     fun point(latticeX: Int, latticeY: Int): Pt =
-        Pt(centreX + latticeX * unitX, centreY - latticeY * unitY)
+        Pt(centreX + (latticeX - midX) * unitX, centreY - (latticeY - midY) * unitY)
 
     fun hexCenter(hex: Int): Pt {
-        val (lx, ly) = CatanBoard.hexCenter(hex)
+        val (lx, ly) = topo.hexCenter(hex)
         return point(lx, ly)
     }
 
     fun vertex(vertex: Int): Pt {
-        val (lx, ly) = CatanBoard.VERTEX_POS[vertex]
+        val (lx, ly) = topo.VERTEX_POS[vertex]
         return point(lx, ly)
     }
 
-    fun hexCorners(hex: Int): List<Pt> = CatanBoard.HEX_CORNERS[hex].map { vertex(it) }
+    fun hexCorners(hex: Int): List<Pt> = topo.HEX_CORNERS[hex].map { vertex(it) }
 
     fun edgeEnds(edge: Int): Pair<Pt, Pt> {
-        val (a, b) = CatanBoard.EDGE_VERTICES[edge]
+        val (a, b) = topo.EDGE_VERTICES[edge]
         return vertex(a) to vertex(b)
     }
 
@@ -62,8 +69,15 @@ class BoardLayout(
      */
     fun portAnchor(edge: Int): Pt {
         val mid = edgeMidpoint(edge)
-        val dx = mid.x - centreX
-        val dy = mid.y - centreY
+        // Straight out from the middle of the island on the standard board; on a map of
+        // islands, straight out from the land hex the harbour sits on.
+        val from = if (topo.EDGE_HEXES[edge].size == 1) {
+            Pt(centreX, centreY)
+        } else {
+            topo.EDGE_HEXES[edge].firstOrNull { topo.land[it] }?.let { hexCenter(it) } ?: Pt(centreX, centreY)
+        }
+        val dx = mid.x - from.x
+        val dy = mid.y - from.y
         val length = sqrt(dx * dx + dy * dy).coerceAtLeast(1f)
         return Pt(mid.x + dx / length * radius * PORT_OFFSET, mid.y + dy / length * radius * PORT_OFFSET)
     }
@@ -97,23 +111,29 @@ class BoardLayout(
 
 object CatanGeometry {
 
-    /** Lattice extents of the island: x spans -5..5, y spans -8..8. */
-    private const val LATTICE_X_UNITS = 10
-    private const val LATTICE_Y_UNITS = 16
-
     /** Empty space round the island, in hex radii, for the sea and the harbours. */
     const val MARGIN = 1.75f
 
-    private val boardWidthInRadii = LATTICE_X_UNITS * SQRT3 / 2f + 2 * MARGIN
-    private val boardHeightInRadii = LATTICE_Y_UNITS / 2f + 2 * MARGIN
+    /** A Seafarers frame already ends in a ring of sea, so it needs almost none. */
+    private const val FRAME_MARGIN = 0.3f
+
+    private fun margin(topo: Topology) = if (topo.land.all { it }) MARGIN else FRAME_MARGIN
+
+    private fun widthInRadii(topo: Topology) =
+        (topo.lattice[1] - topo.lattice[0]) * SQRT3 / 2f + 2 * margin(topo)
+
+    private fun heightInRadii(topo: Topology) =
+        (topo.lattice[3] - topo.lattice[2]) / 2f + 2 * margin(topo)
 
     /** Width ÷ height of the board including its margin, for sizing its box. */
-    val ASPECT: Float = boardWidthInRadii / boardHeightInRadii
+    val ASPECT: Float = widthInRadii(CatanBoard.base) / heightInRadii(CatanBoard.base)
+
+    fun aspect(topo: Topology): Float = widthInRadii(topo) / heightInRadii(topo)
 
     /** The largest layout that fits [width] × [height] pixels. */
-    fun fit(width: Float, height: Float): BoardLayout {
-        val radius = minOf(width / boardWidthInRadii, height / boardHeightInRadii)
-        return BoardLayout(width, height, radius)
+    fun fit(width: Float, height: Float, topo: Topology = CatanBoard.base): BoardLayout {
+        val radius = minOf(width / widthInRadii(topo), height / heightInRadii(topo))
+        return BoardLayout(width, height, radius, topo)
     }
 }
 

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

@@ -0,0 +1,460 @@
+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 -> "♞"
+        BuildKind.SHIP -> "⛵"
+    }
+
+    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
+        BuildKind.SHIP -> CatanText.SHIP
+    }
+}
+
+/** ✓ 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

@@ -5,6 +5,10 @@ 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.BuildShip
+import org.prolibertate.games.game.catan.MovePirate
+import org.prolibertate.games.game.catan.MoveShip
+import org.prolibertate.games.game.catan.Topology
 import org.prolibertate.games.game.catan.BuildSettlement
 import org.prolibertate.games.game.catan.BuildWall
 import org.prolibertate.games.game.catan.BuyDevCard
@@ -35,6 +39,7 @@ 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.PickGold
 import org.prolibertate.games.game.catan.PillageCity
 import org.prolibertate.games.game.catan.PlaceKnight
 import org.prolibertate.games.game.catan.PlaceMetropolis
@@ -59,10 +64,16 @@ import org.prolibertate.games.game.catan.Track
  * only in Cities & Knights; the base game's build menu lists the first three.
  */
 enum class BuildKind {
-    ROAD, SETTLEMENT, CITY, WALL, KNIGHT;
+    ROAD, SETTLEMENT, CITY, WALL, KNIGHT,
+
+    /** Seafarers: a ship, laid on a sea edge. */
+    SHIP;
 
     companion object {
         val BASE: List<BuildKind> = listOf(ROAD, SETTLEMENT, CITY)
+
+        /** Seafarers adds the ship, listed after the road it sails beside. */
+        val SEAFARERS: List<BuildKind> = listOf(ROAD, SHIP, SETTLEMENT, CITY)
     }
 }
 
@@ -76,11 +87,14 @@ data class BoardTargets(
     val edges: Set<Int> = emptySet(),
     val hexes: Set<Int> = emptySet(),
     val knights: Set<Int> = emptySet(),
+    /** Seafarers: the player's ships that can sail this turn, tapped to pick one up. */
+    val ships: 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() && knights.isEmpty() && idleKnights.isEmpty()
+        get() = vertices.isEmpty() && edges.isEmpty() && hexes.isEmpty() && knights.isEmpty() &&
+            idleKnights.isEmpty() && ships.isEmpty()
 
     /** Every crossing a tap can land on. */
     val tappableVertices: Set<Int> get() = vertices + knights + idleKnights
@@ -109,8 +123,11 @@ sealed interface TapOutcome {
     /** Setup: remember this settlement; the road that goes with it is tapped next. */
     data class PickSetupVertex(val vertex: Int) : TapOutcome
 
-    /** The robber's hex has more than one possible victim: ask which. */
-    data class PickRobberVictim(val hex: HexCoord, val victims: List<Int>) : TapOutcome
+    /** The robber's (or the pirate's) hex has more than one possible victim: ask which. */
+    data class PickRobberVictim(val hex: HexCoord, val victims: List<Int>, val pirate: Boolean = false) : TapOutcome
+
+    /** Seafarers: one of the player's ships was tapped; its destination is tapped next. */
+    data class PickShip(val edge: Int) : TapOutcome
 
     /** One of the player's own knights was tapped: open its menu. */
     data class PickKnight(val vertex: Int) : TapOutcome
@@ -142,6 +159,43 @@ 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 BuildShip || 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 BuildShip -> 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(
@@ -153,6 +207,8 @@ object CatanInteraction {
         armed: ArmedCard? = null,
         /** The local seat, so its sleeping knights can be tapped for their menu too. */
         localSeat: Int? = null,
+        /** Seafarers: the ship that has been picked up and is waiting for a destination. */
+        movingShip: Int? = null,
     ): BoardTargets {
         val setup = legal.filterIsInstance<SetupPlace>()
         if (setup.isNotEmpty()) {
@@ -164,8 +220,11 @@ object CatanInteraction {
         }
 
         val robber = legal.filterIsInstance<MoveRobber>()
-        if (robber.isNotEmpty()) {
-            return BoardTargets(hexes = robber.mapNotNull { CatanBoard.hexIndex[it.hex] }.toSet())
+        val pirate = legal.filterIsInstance<MovePirate>()
+        if (robber.isNotEmpty() || pirate.isNotEmpty()) {
+            return BoardTargets(
+                hexes = (robber.map { it.hex } + pirate.map { it.hex }).mapNotNull { state.topo.hexIndex[it] }.toSet(),
+            )
         }
 
         // Cities & Knights: answers to a queued chore are taps on the board.
@@ -173,7 +232,14 @@ object CatanInteraction {
         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)
+        val ships = legal.filterIsInstance<BuildShip>().map { it.edge }.toSet()
+        if (state.phase == CatanPhase.FREE_ROADS) return BoardTargets(edges = roads + ships)
+
+        if (movingShip != null) {
+            return BoardTargets(
+                edges = legal.filterIsInstance<MoveShip>().filter { it.from == movingShip }.map { it.to }.toSet(),
+            )
+        }
 
         if (armed != null) return armedTargets(armed)
 
@@ -185,6 +251,7 @@ object CatanInteraction {
 
         return when (building) {
             BuildKind.ROAD -> BoardTargets(edges = roads)
+            BuildKind.SHIP -> BoardTargets(edges = ships)
             BuildKind.SETTLEMENT ->
                 BoardTargets(vertices = legal.filterIsInstance<BuildSettlement>().map { it.vertex }.toSet())
 
@@ -204,7 +271,11 @@ object CatanInteraction {
                 } else {
                     emptySet()
                 }
-                BoardTargets(knights = ready, idleKnights = mine - ready)
+                BoardTargets(
+                    knights = ready,
+                    idleKnights = mine - ready,
+                    ships = legal.filterIsInstance<MoveShip>().map { it.from }.toSet(),
+                )
             }
         }
     }
@@ -314,6 +385,15 @@ object CatanInteraction {
 
     // --- Cities & Knights: goods ----------------------------------------------
 
+    /** The gold pick that names exactly [selection], if the engine allows it. */
+    fun goldMove(legal: List<CatanMove>, selection: List<Resource>): PickGold? {
+        val want = selection.groupingBy { it }.eachCount()
+        return legal.filterIsInstance<PickGold>().firstOrNull { it.cards.groupingBy { c -> c }.eachCount() == want }
+    }
+
+    /** How many cards the gold pick on offer must name. */
+    fun goldCount(legal: List<CatanMove>): Int = legal.filterIsInstance<PickGold>().firstOrNull()?.cards?.size ?: 0
+
     /** 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>()
@@ -396,6 +476,8 @@ object CatanInteraction {
         building: BuildKind?,
         setupVertex: Int?,
         armed: ArmedCard? = null,
+        /** Seafarers: the ship picked up and waiting for a destination. */
+        movingShip: Int? = null,
     ): TapOutcome {
         if (legal.any { it is SetupPlace }) {
             if (setupVertex == null) return TapOutcome.Ignored
@@ -406,21 +488,51 @@ object CatanInteraction {
             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 (movingShip != null) {
+            val move = MoveShip(movingShip, edge)
+            return if (move in legal) TapOutcome.Submit(move) else TapOutcome.Ignored
+        }
+        // Free roads (and free ships) need no build mode; a paid one does.
+        val free = legal.any { it is EndFreeRoads }
+        if (building == BuildKind.SHIP || (free && BuildShip(edge) in legal)) {
+            val move = BuildShip(edge)
+            return if (move in legal) TapOutcome.Submit(move) else TapOutcome.Ignored
+        }
+        if (building == null && !free) {
+            // Nothing armed: tapping one of your own ships that can sail picks it up.
+            return if (legal.any { it is MoveShip && it.from == edge }) TapOutcome.PickShip(edge) else TapOutcome.Ignored
+        }
+        val canBuild = building == BuildKind.ROAD || free
         if (!canBuild) return TapOutcome.Ignored
         val move = BuildRoad(edge)
         return if (move in legal) TapOutcome.Submit(move) else TapOutcome.Ignored
     }
 
-    fun onHexTap(hex: Int, legal: List<CatanMove>, armed: ArmedCard? = null): TapOutcome {
+    fun onHexTap(
+        hex: Int,
+        legal: List<CatanMove>,
+        armed: ArmedCard? = null,
+        /** The board the hex index belongs to (the standard island unless the game is Seafarers). */
+        topo: Topology = CatanBoard.base,
+    ): TapOutcome {
         if (armed != null) return onArmedHexTap(hex, legal, armed)
-        val coord = CatanBoard.HEXES.getOrNull(hex) ?: return TapOutcome.Ignored
+        val coord = topo.HEXES.getOrNull(hex) ?: return TapOutcome.Ignored
         val moves = legal.filterIsInstance<MoveRobber>().filter { it.hex == coord }
+        val pirates = legal.filterIsInstance<MovePirate>().filter { it.hex == coord }
         return when {
-            moves.isEmpty() -> TapOutcome.Ignored
-            moves.size == 1 -> TapOutcome.Submit(moves.first())
-            else -> TapOutcome.PickRobberVictim(coord, moves.mapNotNull { it.victim })
+            moves.isNotEmpty() -> if (moves.size == 1) {
+                TapOutcome.Submit(moves.first())
+            } else {
+                TapOutcome.PickRobberVictim(coord, moves.mapNotNull { it.victim })
+            }
+
+            pirates.isNotEmpty() -> if (pirates.size == 1) {
+                TapOutcome.Submit(pirates.first())
+            } else {
+                TapOutcome.PickRobberVictim(coord, pirates.mapNotNull { it.victim }, pirate = true)
+            }
+
+            else -> TapOutcome.Ignored
         }
     }
 
@@ -458,7 +570,7 @@ object CatanInteraction {
         }
         val total = state.lastDice.sum()
         if (total == 7) return emptySet()
-        return (0 until CatanBoard.HEX_COUNT)
+        return (0 until state.topo.HEX_COUNT)
             .filter { state.numbers[it] == total && it != state.robber }
             .toSet()
     }
@@ -471,6 +583,7 @@ object CatanInteraction {
 
     fun canBuild(legal: List<CatanMove>): Set<BuildKind> = buildSet {
         if (legal.any { it is BuildRoad }) add(BuildKind.ROAD)
+        if (legal.any { it is BuildShip }) add(BuildKind.SHIP)
         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)

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

@@ -597,6 +597,7 @@ private fun buildLabel(kind: BuildKind): String = when (kind) {
     BuildKind.CITY -> CatanText.CITY
     BuildKind.WALL -> CatanText.WALL
     BuildKind.KNIGHT -> CatanText.KNIGHT
+    BuildKind.SHIP -> CatanText.SHIP
 }
 
 private fun buildCost(kind: BuildKind): String = when (kind) {
@@ -605,6 +606,7 @@ private fun buildCost(kind: BuildKind): String = when (kind) {
     BuildKind.CITY -> CatanText.CITY_COST
     BuildKind.WALL -> CatanText.WALL_COST
     BuildKind.KNIGHT -> CatanText.KNIGHT_COST
+    BuildKind.SHIP -> CatanText.SHIP_COST_TEXT
 }
 
 @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
@@ -22,6 +31,7 @@ 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
@@ -47,6 +57,7 @@ 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.MoveShip
 import org.prolibertate.games.game.catan.MoveRobber
 import org.prolibertate.games.game.catan.PickDeckChore
 import org.prolibertate.games.game.catan.RollDice
@@ -102,8 +113,22 @@ fun CatanScreen(
     var knightMenu by remember { mutableStateOf<Int?>(null) }
     var movingKnight by remember { mutableStateOf<Int?>(null) }
     var armed by remember { mutableStateOf<ArmedCard?>(null) }
+    // Seafarers: the ship that has been picked up and is waiting for somewhere to sail.
+    var movingShip by remember { mutableStateOf<Int?>(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) }
@@ -114,10 +139,12 @@ 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
+        if (movingShip != null && legal.none { it is MoveShip && it.from == movingShip }) movingShip = null
         armed?.let { card -> if (card.plays.none { it in legal }) armed = null }
         if (legal.isEmpty()) {
             showCards = false
@@ -128,6 +155,7 @@ fun CatanScreen(
             knightMenu = null
             movingKnight = null
             armed = null
+            staged = null
         }
     }
 
@@ -142,7 +170,11 @@ fun CatanScreen(
         showProgress = false
         knightMenu = null
         movingKnight = null
+        movingShip = null
         armed = null
+        staged = null
+        dragKind = null
+        dragAt = null
     }
 
     val endGameAction: @Composable () -> Unit = {
@@ -159,13 +191,17 @@ fun CatanScreen(
         return
     }
 
-    val targets = CatanInteraction.targets(current, legal, building, setupVertex, movingKnight, armed, localSeat)
+    val targets = CatanInteraction.targets(current, legal, building, setupVertex, movingKnight, armed, localSeat, movingShip)
     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,
+        buildKinds = when {
+            current.isCk -> BuildKind.entries.filter { it != BuildKind.SHIP }
+            current.isSea -> BuildKind.SEAFARERS
+            else -> BuildKind.BASE
+        },
         ck = current.isCk,
         canImprove = CatanInteraction.improvable(legal).isNotEmpty(),
         canPlayProgress = progressHand.any { it.playable },
@@ -189,16 +225,22 @@ fun CatanScreen(
         building = building,
         movingKnight = movingKnight != null,
         armed = armed?.kind,
+        movingShip = movingShip != null,
     )
 
     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.PickShip -> movingShip = outcome.edge
             is TapOutcome.PickFirstHex -> armed = armed?.copy(firstHex = outcome.hex)
+            }
         }
     }
 
@@ -210,10 +252,14 @@ 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,
@@ -227,12 +273,15 @@ fun CatanScreen(
                                 ),
                             )
                         },
-                        onEdgeTap = { handle(CatanInteraction.onEdgeTap(it, legal, building, setupVertex, armed)) },
-                        onHexTap = { handle(CatanInteraction.onHexTap(it, legal, armed)) },
+                        onEdgeTap = { handle(CatanInteraction.onEdgeTap(it, legal, building, setupVertex, armed, movingShip)) },
+                        onHexTap = { handle(CatanInteraction.onHexTap(it, legal, armed, current.topo)) },
                         modifier = boardModifier,
                         style = style,
                         rolledHexes = rolledHexes,
                         selectedKnight = movingKnight ?: knightMenu,
+                        stagedVertex = ghostVertex,
+                        stagedEdge = ghostEdge,
+                        stagedSeat = localSeat,
                     )
                 }
                 val players: @Composable (Boolean) -> Unit = { grid ->
@@ -265,21 +314,61 @@ fun CatanScreen(
                 }
 
                 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)
-                            if (current.isCk) CatanBarbarians(current, style = style)
-                            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, movingShip)
+                                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)
@@ -291,6 +380,39 @@ 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(
@@ -432,7 +554,6 @@ private fun CatanDialogHost(
     onCancelCards: () -> Unit,
     onCancelTrade: () -> Unit,
 ) {
-    val offer = state.pendingTrade
     val goodsOffer = state.ck?.goodsOffer
     when {
         abandoned != null -> CatanAbandonedDialog(abandoned, onExit, onStay)
@@ -450,6 +571,9 @@ private fun CatanDialogHost(
                 onSubmit = onSubmit,
             )
 
+        state.phase == CatanPhase.GOLD && CatanRules.currentSeat(state) == localSeat && legal.isNotEmpty() ->
+            CatanGoldDialog(legal, onSubmit)
+
         state.phase == CatanPhase.CHORE && CatanRules.currentSeat(state) == localSeat ->
             ChoreDialog(state, localSeat, legal, onSubmit)
 
@@ -473,18 +597,6 @@ private fun CatanDialogHost(
                 onNoDeal = { onSubmit(DismissCounters) },
             )
 
-        state.phase == CatanPhase.TRADE_PENDING && offer != null && offer.asking == localSeat ->
-            CatanTradeResponseDialog(
-                state = state,
-                seat = localSeat,
-                offer = offer,
-                seats = seats,
-                canAccept = CatanInteraction.tradeResponses(legal).first,
-                onAccept = { onSubmit(AcceptTrade) },
-                onDecline = { onSubmit(DeclineTrade) },
-                onCounter = onSubmit,
-            )
-
         state.phase == CatanPhase.TRADE_COUNTERS && state.turn == localSeat && legal.isNotEmpty() ->
             CatanCounterChoiceDialog(
                 counters = CatanInteraction.counterChoices(state, legal),
@@ -497,7 +609,15 @@ private fun CatanDialogHost(
             CatanVictimDialog(
                 victims = victimChoice.victims,
                 seats = seats,
-                onPick = { victim -> onSubmit(MoveRobber(victimChoice.hex, victim)) },
+                onPick = { victim ->
+                    onSubmit(
+                        if (victimChoice.pirate) {
+                            org.prolibertate.games.game.catan.MovePirate(victimChoice.hex, victim)
+                        } else {
+                            MoveRobber(victimChoice.hex, victim)
+                        },
+                    )
+                },
                 onCancel = onCancelVictim,
             )
 
@@ -541,17 +661,6 @@ private fun CatanDialogHost(
                 onOffer = onSubmit,
                 onCancel = onCancelTrade,
             )
-
-        showTrade ->
-            CatanTradeDialog(
-                state = state,
-                seat = localSeat,
-                seats = seats,
-                legal = legal,
-                onBank = onSubmit,
-                onOffer = onSubmit,
-                onCancel = onCancelTrade,
-            )
     }
 }
 
@@ -612,3 +721,11 @@ private fun ChoreDialog(
         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

@@ -81,6 +81,9 @@ data class CatanStyle(
     val citySize: Float = 0.42f,
     val tokenRadius: Float = 0.36f,
     val robberSize: Float = 0.34f,
+    /** Seafarers: the pirate's flag, and the hull and sail of a ship. */
+    val pirate: Color = Color(0xFF000000),
+    val shipSail: Color = Color(0xFFFFFFFF),
     val portRadius: Float = 0.46f,
     val targetRadius: Float = 0.20f,
     /** How close a tap must land to a vertex / edge / hex centre to count. */
@@ -118,6 +121,9 @@ private val LightStyle = CatanStyle(
         Terrain.HILLS to Color(0xFFB4532F),
         Terrain.MOUNTAINS to Color(0xFF7C8794),
         Terrain.DESERT to Color(0xFFE6D3A0),
+        // Seafarers. Sea hexes are drawn as a faint wash over the water; gold is a rich yellow.
+        Terrain.SEA to Color(0xFF3A7CA5),
+        Terrain.GOLD to Color(0xFFF2B01E),
     ),
     hexEdge = Color(0x55000000),
     token = Color(0xFFF7EFD9),

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

@@ -72,6 +72,8 @@ object CatanText {
         Terrain.HILLS -> "Hills"
         Terrain.MOUNTAINS -> "Mountains"
         Terrain.DESERT -> "Desert"
+        Terrain.SEA -> "Sea"
+        Terrain.GOLD -> "Gold field"
     }
 
     fun devCard(type: DevCardType): String = when (type) {
@@ -108,6 +110,11 @@ object CatanText {
 
     // --- Buttons and headings --------------------------------------------------
 
+    const val SEA_ROBBER = "Move the robber (tap a land hex) or the pirate (tap a sea hex)."
+    const val SHIP = "Ship"
+    const val SHIP_COST_TEXT = "1 lumber + 1 wool"
+    const val GOLD_TITLE = "Gold field"
+    const val GOLD_TAKE = "Take"
     const val ROLL = "Roll dice"
     const val END_TURN = "End turn"
     const val ROAD = "Road"
@@ -139,6 +146,28 @@ 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"
@@ -161,6 +190,8 @@ object CatanText {
         movingKnight: Boolean = false,
         /** Cities & Knights: a progress card is waiting for a tap on the board. */
         armed: ProgressType? = null,
+        /** Seafarers: a ship has been picked to sail, and its destination is awaited. */
+        movingShip: Boolean = false,
     ): String {
         if (state.isCk) return ckPrompt(state, seats, setupVertexChosen, building, movingKnight, armed)
         val me = seats.me
@@ -198,10 +229,23 @@ object CatanText {
             }
 
             CatanPhase.ROBBER ->
-                if (mine) "Move the robber. Tap a hex." else "$turn is moving the robber…"
+                if (mine) {
+                    if (state.isSea) SEA_ROBBER else "Move the robber. Tap a hex."
+                } else {
+                    "$turn is moving the robber…"
+                }
+
+            CatanPhase.GOLD ->
+                if (mine) {
+                    "Gold! Choose ${state.sea?.gold?.firstOrNull()?.count ?: 1} resource cards."
+                } else {
+                    "${seats.label(onClock ?: state.turn)} is choosing from the gold…"
+                }
 
             CatanPhase.PLAYING -> when {
                 !mine -> "$turn is playing…"
+                movingShip -> "Tap the sea edge to sail the ship to."
+                building == BuildKind.SHIP -> "Tap a sea edge beside your fleet or a harbour town to launch a ship."
                 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."
@@ -364,6 +408,8 @@ object CatanText {
         val ck = state.ck!!
 
         return when (state.phase) {
+            CatanPhase.GOLD -> ""
+
             CatanPhase.GAME_OVER -> {
                 val winner = state.winner
                 if (winner == null) "The game is over." else "${seats.label(winner)} won the game."

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/CatanSeafarersTest.kt

@@ -0,0 +1,325 @@
+package org.prolibertate.games.game.catan
+
+import kotlinx.serialization.encodeToString
+import kotlinx.serialization.json.Json
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertFalse
+import org.junit.Assert.assertNotEquals
+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
+
+class CatanSeafarersTest {
+
+    private val json = Json { encodeDefaults = true }
+
+    private fun options(players: Int = 3) =
+        CatanOptions(playerCount = players, pointsToWin = 12, ruleSet = CatanRuleSet.SEAFARERS)
+
+    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,
+    )
+
+    private fun start(players: Int = 3, seed: Long = 7L): CatanState =
+        CatanRules.initialState(config(options(players), seed))
+
+    /** A mid-game table on seat 0's turn with plenty of cards. */
+    private fun playing(seed: Long = 7L, adjust: CatanState.() -> CatanState = { this }): CatanState =
+        start(seed = seed).copy(
+            phase = CatanPhase.PLAYING,
+            turn = 0,
+            turnNumber = 1,
+            resources = List(3) { Resource.entries.associateWith { 5 } },
+        ).adjust()
+
+    private fun CatanState.settle(vertex: Int, seat: Int, type: BuildingType = BuildingType.SETTLEMENT) =
+        copy(buildings = buildings.toMutableList().also { it[vertex] = CatanBuilding(type, seat) })
+
+    private fun CatanState.withShip(edge: Int, seat: Int) =
+        copy(sea = sea!!.let { it.copy(ships = it.ships.toMutableList().also { l -> l[edge] = seat }) })
+
+    private fun CatanState.withRoad(edge: Int, seat: Int) =
+        copy(roads = roads.toMutableList().also { it[edge] = seat })
+
+    /** A home-island vertex that touches open water, with a sea edge leaving it. */
+    private fun CatanState.coastVertex(): Int {
+        val topo = topo
+        return (0 until topo.VERTEX_COUNT).first { v ->
+            topo.vertexIsland[v] == sea!!.home &&
+                topo.VERTEX_EDGES[v].any { topo.edgeSea[it] && !topo.edgeLand[it] }
+        }
+    }
+
+    // --- The map -------------------------------------------------------------
+
+    @Test
+    fun `the new shores map is a big home island and three small ones`() {
+        val topo = SeaBoards.topology(SeaScenario.NEW_SHORES)
+        assertEquals(4, topo.islandCount)
+        val sizes = (0 until topo.islandCount).map { i -> topo.islandOf.count { it == i } }.sorted()
+        assertEquals(listOf(2, 3, 3, 21), sizes)
+        // Every coast is closed: nothing on land touches the edge of the frame.
+        for (e in 0 until topo.EDGE_COUNT) {
+            if (topo.EDGE_HEXES[e].size == 1) assertFalse("land on the frame edge at $e", topo.land[topo.EDGE_HEXES[e][0]])
+        }
+    }
+
+    @Test
+    fun `a new game has gold, a desert, numbers on every other land hex, a pirate at sea and nine harbours`() {
+        repeat(5) { i ->
+            val s = start(seed = 100L + i)
+            val topo = s.topo
+            assertEquals(2, s.terrains.count { it == Terrain.GOLD })
+            assertEquals(1, s.terrains.count { it == Terrain.DESERT })
+            for (h in 0 until topo.HEX_COUNT) {
+                val land = s.terrains[h] != Terrain.SEA
+                assertEquals("hex $h", topo.land[h], land)
+                assertEquals("hex $h", land && s.terrains[h] != Terrain.DESERT, s.numbers[h] != 0)
+            }
+            assertEquals(Terrain.SEA, s.terrains[s.sea!!.pirate])
+            assertTrue(s.terrains[s.robber] == Terrain.DESERT)
+            assertEquals(9, s.ports.size)
+            // The red numbers are never neighbours.
+            val reds = (0 until topo.HEX_COUNT).filter { s.numbers[it] == 6 || s.numbers[it] == 8 }
+            for (a in reds) for (b in reds) if (a < b) assertFalse(topo.hexesAdjacent(a, b))
+        }
+    }
+
+    @Test
+    fun `setup places both settlements on the home island, with roads rather than ships`() {
+        val s = start()
+        val moves = CatanRules.legalMoves(s, 0).filterIsInstance<SetupPlace>()
+        assertTrue(moves.isNotEmpty())
+        assertTrue(moves.all { s.topo.vertexIsland[it.vertex] == s.sea!!.home })
+        assertTrue(moves.all { s.topo.edgeLand[it.edge] })
+    }
+
+    @Test
+    fun `the state survives its wire format`() {
+        val s = playing().let { it.settle(it.coastVertex(), 0) }
+        assertEquals(s, CatanRules.decodeState(CatanRules.encodeState(s)))
+    }
+
+    // --- Ships ---------------------------------------------------------------
+
+    @Test
+    fun `a ship launches from a harbour town onto a sea edge and costs a lumber and a wool`() {
+        val s = playing().let { it.settle(it.coastVertex(), 0) }
+        val ships = CatanRules.legalMoves(s, 0).filterIsInstance<BuildShip>()
+        assertTrue(ships.isNotEmpty())
+        assertTrue(ships.all { s.topo.edgeSea[it.edge] })
+        val after = CatanRules.applyMove(s, 0, ships.first())
+        assertEquals(0, after.sea!!.ships.indexOfFirst { it == 0 }.let { if (it == ships.first().edge) 0 else 1 })
+        assertEquals(4, after.resources[0].getValue(Resource.LUMBER))
+        assertEquals(4, after.resources[0].getValue(Resource.WOOL))
+        assertEquals(5, after.resources[0].getValue(Resource.BRICK))
+    }
+
+    @Test
+    fun `no ship without the cards, and none sails out of nothing`() {
+        val bare = playing().let { it.settle(it.coastVertex(), 0) }
+            .let { it.copy(resources = it.resources.toMutableList().also { r -> r[0] = Resource.entries.associateWith { 0 } }) }
+        assertTrue(CatanRules.legalMoves(bare, 0).none { it is BuildShip })
+        // Nobody has a town or a fleet: there is nowhere to start from.
+        val nothing = playing()
+        assertTrue(CatanRules.legalMoves(nothing, 0).none { it is BuildShip })
+    }
+
+    @Test
+    fun `the pirate keeps ships off the edges round its hex`() {
+        val s = playing().let { it.settle(it.coastVertex(), 0) }
+        val ship = CatanRules.legalMoves(s, 0).filterIsInstance<BuildShip>().first()
+        val seaHex = s.topo.EDGE_HEXES[ship.edge].first { !s.topo.land[it] }
+        val blocked = s.copy(sea = s.sea!!.copy(pirate = seaHex))
+        assertTrue(CatanRules.legalMoves(blocked, 0).filterIsInstance<BuildShip>().none { seaHex in s.topo.EDGE_HEXES[it.edge] })
+    }
+
+    @Test
+    fun `a ship cannot sail the turn it is built, but can the next, from the open end only`() {
+        val s0 = playing().let { it.settle(it.coastVertex(), 0) }
+        val first = CatanRules.legalMoves(s0, 0).filterIsInstance<BuildShip>().first()
+        val s1 = CatanRules.applyMove(s0, 0, first)
+        assertTrue(CatanRules.legalMoves(s1, 0).none { it is MoveShip })
+
+        // Next turn (after the others pass), the lone ship is at an open end and can sail.
+        val s2 = s1.copy(sea = s1.sea!!.copy(builtThisTurn = emptyList(), shipMoved = false))
+        val sails = CatanRules.legalMoves(s2, 0).filterIsInstance<MoveShip>()
+        assertTrue(sails.isNotEmpty())
+        assertTrue(sails.all { it.from == first.edge && it.to != first.edge })
+
+        // Sailing uses the turn's one move.
+        val s3 = CatanRules.applyMove(s2, 0, sails.first())
+        assertTrue(s3.sea!!.shipMoved)
+        assertEquals(NO_PLAYER, s3.sea!!.ships[first.edge])
+        assertEquals(0, s3.sea!!.ships[sails.first().to])
+        assertTrue(CatanRules.legalMoves(s3, 0).none { it is MoveShip })
+    }
+
+    @Test
+    fun `a ship in the middle of a route is stuck`() {
+        // Town - ship A - ship B: A has the town at one end and B at the other, so only B is at an open end.
+        val s0 = playing().let { it.settle(it.coastVertex(), 0) }
+        val a = CatanRules.legalMoves(s0, 0).filterIsInstance<BuildShip>().first().edge
+        var s = s0.withShip(a, 0)
+        val far = s.topo.EDGE_VERTICES[a].toList().first { s.buildings[it] == null }
+        val b = s.topo.VERTEX_EDGES[far].first { it != a && s.topo.edgeSea[it] && s.roads[it] == NO_PLAYER }
+        s = s.withShip(b, 0)
+        val movers = CatanRules.legalMoves(s, 0).filterIsInstance<MoveShip>().map { it.from }.toSet()
+        assertEquals(setOf(b), movers)
+    }
+
+    @Test
+    fun `a settlement can rise at the end of a ship route, and the first on a new island scores the bonus`() {
+        val base = playing()
+        val topo = base.topo
+        val sea = base.sea!!
+        // A vertex on a small island, and a ship chain reaching it is too long to build by hand,
+        // so give the player the ship on the edge beside that vertex.
+        val vertex = (0 until topo.VERTEX_COUNT).first { v ->
+            val island = topo.vertexIsland[v]
+            island != -1 && island != sea.home &&
+                topo.VERTEX_EDGES[v].any { topo.edgeSea[it] }
+        }
+        val edge = topo.VERTEX_EDGES[vertex].first { topo.edgeSea[it] }
+        var s = base.withShip(edge, 0)
+        assertTrue(CatanRules.legalMoves(s, 0).any { it == BuildSettlement(vertex) })
+
+        val before = CatanRules.publicVictoryPoints(s)[0]
+        s = CatanRules.applyMove(s, 0, BuildSettlement(vertex))
+        assertEquals(before + 1 + SeaRules.ISLAND_BONUS, CatanRules.publicVictoryPoints(s)[0])
+        assertEquals(0, s.sea!!.islandBonus[topo.vertexIsland[vertex]])
+
+        // A second settlement on that island scores no second bonus.
+        val again = SeaRules.claimIsland(s, 1, vertex)
+        assertEquals(0, again.sea!!.islandBonus[topo.vertexIsland[vertex]])
+    }
+
+    @Test
+    fun `a road and a ship join a route only at a town of your own`() {
+        val base = playing()
+        val topo = base.topo
+        val v = base.coastVertex()
+        val road = topo.VERTEX_EDGES[v].first { topo.edgeLand[it] }
+        val ship = topo.VERTEX_EDGES[v].first { topo.edgeSea[it] && !topo.edgeLand[it] }
+
+        // With a town at the junction, road + ship is one route of two.
+        val withTown = base.settle(v, 0).withRoad(road, 0).withShip(ship, 0)
+        assertEquals(2, SeaRules.longestRouteFor(withTown, 0))
+
+        // Without it, they are two separate pieces.
+        val noTown = base.withRoad(road, 0).withShip(ship, 0)
+        assertEquals(1, SeaRules.longestRouteFor(noTown, 0))
+    }
+
+    // --- Pirate --------------------------------------------------------------
+
+    @Test
+    fun `on a seven the roller may move the robber to land or the pirate to sea, and the pirate robs a ship's owner`() {
+        val s0 = playing().let { it.settle(it.coastVertex(), 1) }
+        val ship = SeaRules.buildShipMoves(s0, 1).first().edge
+        val s = s0.withShip(ship, 1).copy(phase = CatanPhase.ROBBER)
+        val moves = CatanRules.legalMoves(s, 0)
+        assertTrue(moves.any { it is MoveRobber })
+        assertTrue(moves.any { it is MovePirate })
+        // Robber moves are on land only.
+        assertTrue(moves.filterIsInstance<MoveRobber>().all { s.topo.land[s.topo.hexIndex.getValue(it.hex)] })
+        assertTrue(moves.filterIsInstance<MovePirate>().all { !s.topo.land[s.topo.hexIndex.getValue(it.hex)] })
+
+        val robbery = moves.filterIsInstance<MovePirate>().first { it.victim == 1 }
+        val after = CatanRules.applyMove(s, 0, robbery)
+        assertEquals(CatanPhase.PLAYING, after.phase)
+        assertEquals(s.topo.hexIndex.getValue(robbery.hex), after.sea!!.pirate)
+        assertEquals(s.resourceCount(0) + 1, after.resourceCount(0))
+        assertEquals(s.resourceCount(1) - 1, after.resourceCount(1))
+    }
+
+    // --- Gold ----------------------------------------------------------------
+
+    @Test
+    fun `gold pays a resource of the owner's choice`() {
+        val base = playing()
+        val topo = base.topo
+        val goldHex = base.terrains.indexOf(Terrain.GOLD)
+        val number = base.numbers[goldHex]
+        val v = topo.HEX_CORNERS[goldHex].first { topo.vertexLand[it] }
+        // Seat 0's town beside the gold field; nothing else of theirs produces on that number.
+        val s = base.settle(v, 0).copy(
+            robber = (0 until topo.HEX_COUNT).first { topo.land[it] && it != goldHex && v !in topo.HEX_CORNERS[it] },
+            resources = List(3) { Resource.entries.associateWith { 0 } },
+            phase = CatanPhase.AWAIT_ROLL,
+        )
+        val dice = if (number <= 7) listOf(number - 1, 1) else listOf(6, number - 6)
+        val rolled = CatanRules.applyMove(s, 0, RollDice(forced = dice))
+        assertEquals(CatanPhase.GOLD, rolled.phase)
+        assertEquals(0, CatanRules.currentSeat(rolled))
+        val picks = CatanRules.legalMoves(rolled, 0)
+        assertEquals(Resource.entries.size, picks.size)
+        val after = CatanRules.applyMove(rolled, 0, PickGold(listOf(Resource.ORE)))
+        assertEquals(CatanPhase.PLAYING, after.phase)
+        assertEquals(1, after.resources[0].getValue(Resource.ORE))
+    }
+
+    // --- Whole games ---------------------------------------------------------
+
+    private data class Report(val seed: Long, val moves: Int, val ships: Int, val islandsTaken: Int, val points: List<Int>)
+
+    private fun playOut(options: CatanOptions, seed: Long, cap: Int = 20_000): Pair<CatanState, Report> {
+        val ai = CatanAi()
+        var state = CatanRules.initialState(config(options, seed))
+        var moves = 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 next = CatanRules.applyMove(state, seat, move)
+            // The wire format must carry everything, every step.
+            if (moves % 25 == 0) assertEquals(next, CatanRules.decodeState(CatanRules.encodeState(next)))
+            state = next
+        }
+        val sea = state.sea!!
+        return state to Report(
+            seed, moves,
+            ships = sea.ships.count { it != NO_PLAYER },
+            islandsTaken = sea.islandBonus.count { it != NO_PLAYER },
+            points = CatanRules.publicVictoryPoints(state),
+        )
+    }
+
+    @Test
+    fun `engines finish Seafarers games at three and four players`() {
+        val reports = mutableListOf<Report>()
+        for ((players, seeds) in listOf(3 to listOf(1L, 2L, 3L, 4L), 4 to listOf(5L, 6L, 7L))) {
+            for (seed in seeds) {
+                val (state, report) = playOut(options(players), 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!!) >= state.options.pointsToWin,
+                )
+                reports += report
+            }
+        }
+        println("Seafarers self-play: " + reports.joinToString("; ") {
+            "seed ${it.seed}: ${it.moves} moves, ${it.ships} ships, ${it.islandsTaken} islands, points ${it.points}"
+        })
+        // The engines must actually go to sea in at least some of the games.
+        assertNotEquals("no engine ever built a ship", 0, reports.sumOf { it.ships })
+    }
+}

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/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))
+    }
+}

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

@@ -0,0 +1,149 @@
+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.BuildShip
+import org.prolibertate.games.game.catan.BuildingType
+import org.prolibertate.games.game.catan.CatanAi
+import org.prolibertate.games.game.catan.CatanBuilding
+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.MovePirate
+import org.prolibertate.games.game.catan.MoveRobber
+import org.prolibertate.games.game.catan.MoveShip
+import org.prolibertate.games.game.catan.PickGold
+import org.prolibertate.games.game.catan.Resource
+import org.prolibertate.games.game.catan.Terrain
+import org.prolibertate.games.game.engine.PlayerKind
+import org.prolibertate.games.game.engine.PlayerSlot
+import org.prolibertate.games.game.engine.TableConfig
+
+/** What the screen offers on a Seafarers board: ships, the pirate, and gold. */
+class CatanSeafarersInteractionTest {
+
+    private fun fresh(): CatanState {
+        val options = CatanOptions(playerCount = 3, pointsToWin = 12, ruleSet = CatanRuleSet.SEAFARERS)
+        return CatanRules.initialState(
+            TableConfig(
+                gameId = GameCatalog.CATAN,
+                seats = (0 until 3).map { PlayerSlot(it, "P$it", PlayerKind.AI, it) },
+                optionsJson = Json { encodeDefaults = true }.encodeToString(options),
+                seed = 7L,
+            ),
+        )
+    }
+
+    /** Seat 0, mid-game, a harbour town on the coast of the home island and plenty of cards. */
+    private fun harbour(): CatanState {
+        val s = fresh().copy(
+            phase = CatanPhase.PLAYING,
+            turn = 0,
+            turnNumber = 1,
+            resources = List(3) { Resource.entries.associateWith { 5 } },
+        )
+        val topo = s.topo
+        val v = (0 until topo.VERTEX_COUNT).first { vertex ->
+            topo.vertexIsland[vertex] == s.sea!!.home &&
+                topo.VERTEX_EDGES[vertex].any { topo.edgeSea[it] && !topo.edgeLand[it] }
+        }
+        return s.copy(buildings = s.buildings.toMutableList().also { it[v] = CatanBuilding(BuildingType.SETTLEMENT, 0) })
+    }
+
+    @Test
+    fun `the ship is on the build menu, and arming it lights the sea edges a ship can take`() {
+        val s = harbour()
+        val legal = CatanRules.legalMoves(s, 0)
+        assertTrue(BuildKind.SHIP in CatanInteraction.canBuild(legal))
+
+        val targets = CatanInteraction.targets(s, legal, BuildKind.SHIP, null)
+        assertEquals(legal.filterIsInstance<BuildShip>().map { it.edge }.toSet(), targets.edges)
+
+        val edge = targets.edges.first { !s.topo.edgeLand[it] }
+        assertEquals(
+            TapOutcome.Submit(BuildShip(edge)),
+            CatanInteraction.onEdgeTap(edge, legal, BuildKind.SHIP, null),
+        )
+        // The same tap with the road armed means nothing: a road cannot lie between two sea hexes.
+        assertEquals(TapOutcome.Ignored, CatanInteraction.onEdgeTap(edge, legal, BuildKind.ROAD, null))
+        // A build tap waits for ✓ like any other piece.
+        assertEquals(BuildShip(edge), CatanInteraction.stageable(TapOutcome.Submit(BuildShip(edge)), BuildKind.SHIP))
+    }
+
+    @Test
+    fun `tapping a ship that can sail picks it up, and the next tap on a lit sea edge sails it`() {
+        val s0 = harbour()
+        val built = CatanRules.legalMoves(s0, 0).filterIsInstance<BuildShip>().first()
+        val s = CatanRules.applyMove(s0, 0, built)
+            .let { it.copy(sea = it.sea!!.copy(builtThisTurn = emptyList())) }
+        val legal = CatanRules.legalMoves(s, 0)
+
+        val idle = CatanInteraction.targets(s, legal, null, null)
+        assertEquals(setOf(built.edge), idle.ships)
+        assertEquals(TapOutcome.PickShip(built.edge), CatanInteraction.onEdgeTap(built.edge, legal, null, null))
+
+        val sailing = CatanInteraction.targets(s, legal, null, null, movingShip = built.edge)
+        val to = sailing.edges.first()
+        assertEquals(
+            TapOutcome.Submit(MoveShip(built.edge, to)),
+            CatanInteraction.onEdgeTap(to, legal, null, null, movingShip = built.edge),
+        )
+    }
+
+    @Test
+    fun `after a seven a land hex moves the robber and a sea hex moves the pirate`() {
+        val s = harbour().copy(phase = CatanPhase.ROBBER)
+        val legal = CatanRules.legalMoves(s, 0)
+        val targets = CatanInteraction.targets(s, legal, null, null)
+        val land = targets.hexes.first { s.terrains[it] != Terrain.SEA }
+        val sea = targets.hexes.first { s.terrains[it] == Terrain.SEA }
+
+        val robber = CatanInteraction.onHexTap(land, legal, topo = s.topo)
+        assertTrue(robber is TapOutcome.Submit && robber.move is MoveRobber)
+        val pirate = CatanInteraction.onHexTap(sea, legal, topo = s.topo)
+        assertTrue(pirate is TapOutcome.Submit && pirate.move is MovePirate)
+    }
+
+    @Test
+    fun `a gold pick is found by the cards it names`() {
+        val picks = listOf(PickGold(listOf(Resource.ORE)), PickGold(listOf(Resource.WOOL)))
+        assertEquals(PickGold(listOf(Resource.WOOL)), CatanInteraction.goldMove(picks, listOf(Resource.WOOL)))
+        assertEquals(null, CatanInteraction.goldMove(picks, listOf(Resource.WOOL, Resource.WOOL)))
+        assertEquals(1, CatanInteraction.goldCount(picks))
+    }
+
+    @Test
+    fun `the engines' own choices are always something the screen can make`() {
+        // Every legal move in a played-out game is reachable: a tap, a button or a dialog choice.
+        val ai = CatanAi()
+        var s = fresh()
+        var n = 0
+        while (!CatanRules.isFinished(s) && n++ < 600) {
+            val seat = CatanRules.currentSeat(s) ?: break
+            val legal = CatanRules.legalMoves(s, seat)
+            val ships = legal.filterIsInstance<BuildShip>()
+            if (s.phase == CatanPhase.PLAYING && ships.isNotEmpty()) {
+                val armed = CatanInteraction.targets(s, legal, BuildKind.SHIP, null)
+                ships.forEach { ship ->
+                    assertTrue("ship ${ship.edge} not lit", ship.edge in armed.edges)
+                    assertEquals(TapOutcome.Submit(ship), CatanInteraction.onEdgeTap(ship.edge, legal, BuildKind.SHIP, null))
+                }
+            }
+            legal.filterIsInstance<MoveShip>().forEach { sail ->
+                val lit = CatanInteraction.targets(s, legal, null, null, movingShip = sail.from)
+                assertTrue(sail.to in lit.edges)
+                assertEquals(
+                    TapOutcome.Submit(sail),
+                    CatanInteraction.onEdgeTap(sail.to, legal, null, null, movingShip = sail.from),
+                )
+            }
+            s = CatanRules.applyMove(s, seat, ai.chooseMove(s, seat, legal))
+        }
+    }
+}

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) — and its expansion rule set, [RULES-catan-ck.md](RULES-catan-ck.md) |
+| Katan (catalogue id `catan`) | [RULES-catan.md](RULES-catan.md) — and its expansion rule sets, [RULES-catan-ck.md](RULES-catan-ck.md) and [RULES-catan-seafarers.md](RULES-catan-seafarers.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-seafarers.md

@@ -0,0 +1,71 @@
+# Katan: Seafarers
+
+The Seafarers rule set is chosen at setup next to *Base game* and *Cities & Knights*. It is the base
+game ([RULES-catan.md](RULES-catan.md)) with a sea, ships, a pirate, gold fields and islands to
+settle. Code: `game/catan/CatanSeaRules.kt` (the additions), `CatanSeaBoard.kt` (the map),
+`CatanBoard.kt` (`Topology`, the geometry shared by every map), state behind `CatanState.sea`
+(null in the other rule sets). It cannot be combined with Cities & Knights.
+
+Where the published rules leave room, or where this game differs, it says so below.
+
+## The map
+
+One map, *Heading for New Shores*: a large **home island** (21 hexes, one desert) and three small
+islands (3, 3 and 2 hexes) across the water, inside a ring of sea. Which land hexes are gold, which
+are the desert and where the sea lies is fixed; the **resources on the other hexes, the number tokens
+and the nine harbours are shuffled** for each game. The red numbers (6, 8) are never on neighbouring
+hexes. Players take three or four seats; the default target is **12 points** (menu: 8, 10, 12, 14).
+
+The geometry is the same lattice as the base island, generalised (`Topology`): a hex is land or sea,
+a crossing can hold a town if any hex touching it is land, an edge can hold a road if any hex touching
+it is land and a ship if any hex touching it is sea (so a coastal edge takes either, never both).
+
+## What changes
+
+**Setup.** Both starting settlements (and their roads) go on the home island. A starting piece is a
+road, never a ship. The second settlement collects from the hexes round it as usual (gold pays nothing
+at setup).
+
+**Ships.** A ship costs 1 lumber and 1 wool and lies on a sea edge.
+
+* It must join your fleet or a town of yours: one end of the edge touches your town, or another of your ships.
+  An opponent's town is a wall.
+* Roads and ships connect **only at a town of your own**: a road cannot start from a ship's end, nor a
+  ship from a road's, unless a settlement or city of yours stands on that crossing. A settlement may be
+  built at the end of a ship route exactly as at the end of a road route.
+* No more than 15 ships. Road Building may lay two roads, two ships or one of each.
+* **Sailing.** Once per turn you may move one ship, never one built or moved this turn, and only a ship at the
+  **open end** of a route (one end touches nothing else of yours). It goes to any edge it could be built on
+  with it lifted off.
+
+**The pirate.** Starts in the open sea. On a seven (and with a Knight card) the player moves either the
+robber, to any land hex, or the pirate, to any sea hex. The robber works as before. The pirate **blocks the six
+edges round its hex**: no ship may be built or sail onto them (ships already there stay). It robs one card
+at random from a player with a ship on an edge of its hex.
+
+**Gold.** A gold field has a number like any hex. When it comes up, each town beside it (one card; a city two)
+pays its owner **any resource of their choice**, chosen after the ordinary production is dealt, in seat order from
+the roller. The robber blocks a gold field like any hex. If the bank cannot supply the choice it is limited to
+what it holds.
+
+**New islands.** The first player to settle on each island other than the home island scores **2 bonus points**,
+permanently (`SeaState.islandBonus`). A second settlement there earns nothing extra.
+
+**Longest route.** Longest Road counts roads and ships together, as a path of your pieces that never runs
+through an opponent's town and changes between road and ship only at a town of yours. Five or more, as before.
+
+Everything else (development cards, trading, harbours, Largest Army, the discard on a seven) is the base game.
+
+## Not included
+
+The physical expansion has more scenarios and the Catan Universe app adds more still. These are **out of scope here**:
+fog islands, treasure islands, the oasis, the great canal, the Explorers & Pirates and Cities & Knights combinations,
+the scenarios after the first, and trade ships. The `SeaScenario` enum and `SeaBoards` are built so a second map
+is a new text map and a new enum entry.
+
+## How the AI plays it
+
+It settles first and sails second. A ship is built when a settlement spot reachable by sea (up to five steps from its
+open end) is worth having, with a bonus for an island nobody has landed on, and ahead of a development card when that
+bonus is in play. It chooses the resource it values most from gold, always moves the robber (never the pirate) and does
+not sail ships it has already launched. See `CatanAi.shipValue`.

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 |
 
@@ -169,3 +171,40 @@ Not done yet, in rough priority order:
 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.
+
+## Seafarers on the screen
+
+| Layer | What it adds |
+| --- | --- |
+| `CatanGeometry.kt` | `BoardLayout` and `CatanGeometry.fit` take the game's `Topology`, so a map of islands fits the box like the standard island does |
+| `CatanStyle.kt` | gold-field colour, the pirate's and the ship sail's colours |
+| `CatanBoardView.kt` | sea hexes (a faint grid, no fill), ships (hull with a sail), the pirate (a flagged hull), a ring on ships that can sail |
+| `CatanInteraction.kt` | `BuildKind.SHIP`; `PickShip`, `movingShip`, ship targets; the robber's and the pirate's hexes; `goldMove` |
+| `CatanDialogs.kt` | `CatanGoldDialog`, the choice of what a gold field pays |
+| `CatanScreen.kt` | the picked-up ship, the ship on the build menu / column |
+
+**Interaction model.** Arm *Ship* (or drag it from the build column) and tap a lit sea edge: ✓ places it. To sail,
+tap one of your ships that has a ring, then a lit sea edge. After a seven, tap a land hex for the robber or a sea
+hex for the pirate. A gold field opens a dialog that cannot be dismissed. `CatanSeafarersInteractionTest` checks
+that every build and sail the engine offers has a tap that produces it.