Merge pull request 'Katan: zoom the board in portrait' (#41) from feature/catan-portrait-zoom into dev

Co-Authored-By: Claude Sonnet 5.5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01TWwLCrXa9aFVg8dZsCdLBZ

.github/workflows/release.yml

@@ -49,8 +49,8 @@ jobs:
       - name: Set up Android SDK
         uses: android-actions/setup-android@v4
 
-      - name: Build debug APK
-        run: ./gradlew assembleDebug --no-daemon --stacktrace
+      - name: Build release APK
+        run: ./gradlew assembleRelease --no-daemon --stacktrace
 
       - name: Stage APK for release
         id: stage
@@ -65,7 +65,7 @@ jobs:
           test -n "$offset"
           # Same arithmetic as build.gradle.kts, so the tag names the APK's own number.
           version="v${series}.$(( ${{ github.run_number }} + offset ))"
-          src="app/build/outputs/apk/debug/app-debug.apk"
+          src="app/build/outputs/apk/release/app-release.apk"
           dest="ProLibertateGames-${version}.apk"
           cp "$src" "$dest"
           # The same build again under a name that never changes. GitHub's

CLAUDE.md

@@ -51,14 +51,14 @@ integration:
 
 ## Katan
 
-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
+The island game is catalogue id `catan`, shown as **Katan**. It has two expansions
+(toggles, `CatanOptions.expansions`; none on is the base game): 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
+`CatanState.sea`); the two can be switched on together. 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
+(Cities & Knights also reads `state.topo`, so it runs on a Seafarers map too). 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.

app/build.gradle.kts

@@ -104,6 +104,11 @@ android {
 
     buildTypes {
         release {
+            // Signed with the same key as the debug builds, so a release installs
+            // over what is already on a device; a different key would make the
+            // updater's installs fail with a signature mismatch.
+            signingConfig = signingConfigs.getByName("debug")
+            isDebuggable = false
             isMinifyEnabled = false
             proguardFiles(
                 getDefaultProguardFile("proguard-android-optimize.txt"),

app/src/main/java/org/prolibertate/games/game/backgammon/BackgammonAi.kt

@@ -1,6 +1,9 @@
 package org.prolibertate.games.game.backgammon
 
 import kotlin.random.Random
+import org.prolibertate.games.game.engine.AiLevel
+import org.prolibertate.games.game.engine.AiProfile
+import org.prolibertate.games.game.engine.AiProfiles
 import org.prolibertate.games.game.engine.GameAi
 
 /**
@@ -22,8 +25,19 @@ import org.prolibertate.games.game.engine.GameAi
  * out and its first step returned; the rest follows on the moves after, because
  * the same calculation reaches the same turn.
  */
-class BackgammonAi(private val level: BackgammonLevel? = null) :
-    GameAi<BackgammonState, BackgammonMove> {
+class BackgammonAi(
+    private val profiles: AiProfiles = AiProfiles.DEFAULT,
+    private val level: BackgammonLevel? = null,
+) : GameAi<BackgammonState, BackgammonMove> {
+
+    /**
+     * The turn an easy seat has settled on, so that a deliberate slip is made
+     * once per roll rather than re-rolled on every checker (which would stitch
+     * halves of different turns together).
+     */
+    private var plan: List<BackgammonMove> = emptyList()
+    private var planned = 0
+    private var planRoll = -1
 
     override fun chooseMove(
         state: BackgammonState,
@@ -31,48 +45,104 @@ class BackgammonAi(private val level: BackgammonLevel? = null) :
         legal: List<BackgammonMove>,
     ): BackgammonMove {
         require(legal.isNotEmpty()) { "No legal move for seat $seat" }
-        val setting = level ?: state.options.level
         if (legal.size == 1) return legal.first()
+        val profile = profiles.of(seat)
+        val base = level ?: state.options.level
+        val setting = when (profile.level) {
+            AiLevel.MEDIUM -> base
+            // Easy never looks at the dice to come.
+            AiLevel.EASY -> if (base == BackgammonLevel.STRONG) BackgammonLevel.CLUB else base
+            AiLevel.HARD -> BackgammonLevel.STRONG
+        }
+        val tuning = tuningFor(profile)
 
         val random = Random(state.rollsMade * 31L + state.moveLog.size)
 
         if (setting == BackgammonLevel.CASUAL) {
             // Not thoughtless: it still prefers to hit, to come in off the bar
             // and to bear off, which is most of what a beginner knows.
-            val scored = legal.map { move -> move to rough(state, seat, move) }
+            val scored = legal.map { move -> move to rough(state, seat, move, profile) }
             val best = scored.maxOf { it.second }
             val equal = scored.filter { it.second == best }
             return equal[random.nextInt(equal.size)].first
         }
 
+        val easy = profile.level == AiLevel.EASY
+        if (easy && planRoll == state.rollsMade) {
+            val next = plan.getOrNull(planned)
+            if (next != null && next in legal) {
+                planned++
+                return next
+            }
+        }
+
         val sequences = BackgammonRules.deepestSequences(state, seat)
         if (sequences.isEmpty()) return legal.first()
 
-        var best = sequences.first()
-        var bestScore = -Double.MAX_VALUE
+        val scored = ArrayList<Pair<List<BackgammonMove>, Double>>(sequences.size)
         for (sequence in sequences) {
             val after = BackgammonRules.playSequence(state, seat, sequence)
-            val score = if (setting == BackgammonLevel.STRONG) {
-                // What the position is worth once the dice have had their say.
-                evaluate(after, seat) - averageReply(after, other(seat))
-            } else {
-                evaluate(after, seat)
-            }
-            if (score > bestScore) {
-                bestScore = score
-                best = sequence
-            }
+            scored += sequence to evaluate(after, seat, tuning)
         }
-        return best.first()
+
+        if (setting == BackgammonLevel.STRONG) {
+            // What the position is worth once the dice have had their say. A hard
+            // seat only spends the twenty-one-roll average on the turns that
+            // already look best, which keeps a phone's thinking time bounded.
+            val finalists = if (profile.level == AiLevel.HARD && scored.size > FINALISTS) {
+                scored.sortedByDescending { it.second }.take(FINALISTS)
+            } else {
+                scored
+            }
+            val rescored = finalists.map { (sequence, _) ->
+                val after = BackgammonRules.playSequence(state, seat, sequence)
+                sequence to (evaluate(after, seat, tuning) - averageReply(after, other(seat)))
+            }
+            return chooseFrom(rescored, profile, state, legal)
+        }
+        return chooseFrom(scored, profile, state, legal)
     }
 
+    /** Best sequence first move; an easy seat sometimes takes a worse (but better-half) turn. */
+    private fun chooseFrom(
+        scored: List<Pair<List<BackgammonMove>, Double>>,
+        profile: AiProfile,
+        state: BackgammonState,
+        legal: List<BackgammonMove>,
+    ): BackgammonMove {
+        var best = scored.first()
+        for (entry in scored) if (entry.second > best.second) best = entry
+        var chosen = best.first
+        if (profile.level == AiLevel.EASY) {
+            val ranked = scored.sortedByDescending { it.second }.map { it.first }
+            chosen = profile.pick(ranked)
+            plan = chosen
+            planned = 1
+            planRoll = state.rollsMade
+        }
+        val first = chosen.first()
+        return if (first in legal) first else legal.first()
+    }
+
+    private fun tuningFor(profile: AiProfile): Tuning {
+        val style = profile.style
+        var blot = 1.0 - 0.3 * style.boldness
+        if (profile.level == AiLevel.EASY) blot *= 0.6 // overlooks some of the danger
+        return Tuning(blot, style.boldness, style.spite)
+    }
+
+    /** What a seat's temperament does to the evaluation; [NEUTRAL] is the standard player. */
+    private class Tuning(val blot: Double, val bold: Double, val spite: Double)
+
     /** A quick opinion of one checker, for the level that does not think. */
-    private fun rough(state: BackgammonState, seat: Int, move: BackgammonMove): Int {
+    private fun rough(state: BackgammonState, seat: Int, move: BackgammonMove, profile: AiProfile): Int {
         val landing = BackgammonRules.destinationOf(seat, move.from, move.die)
         var score = 0
         if (move.from == BAR) score += 50
         if (landing == null) score += 40
-        if (landing != null && state.countOn(landing, other(seat)) == 1) score += 60
+        if (landing != null && state.countOn(landing, other(seat)) == 1) {
+            score += 60 + ((profile.style.boldness + profile.style.spite) * 20).toInt()
+        }
         if (landing != null && state.countOn(landing, seat) >= 1) score += 15
         return score
     }
@@ -98,8 +168,8 @@ class BackgammonAi(private val level: BackgammonLevel? = null) :
                 val rolled = state.copy(turn = opponent, dice = dice, roll = listOf(high, low))
                 val replies = BackgammonRules.deepestSequences(rolled, opponent)
                 val bestReply = replies.maxOfOrNull { sequence ->
-                    evaluate(BackgammonRules.playSequence(rolled, opponent, sequence), opponent)
-                } ?: evaluate(rolled, opponent)
+                    evaluate(BackgammonRules.playSequence(rolled, opponent, sequence), opponent, NEUTRAL)
+                } ?: evaluate(rolled, opponent, NEUTRAL)
                 total += chance * bestReply
                 weight += chance
             }
@@ -117,7 +187,7 @@ class BackgammonAi(private val level: BackgammonLevel? = null) :
      * checkers are, and a made point in your own home board is worth having
      * because it is one more number your opponent cannot come in on.
      */
-    private fun evaluate(state: BackgammonState, seat: Int): Double {
+    private fun evaluate(state: BackgammonState, seat: Int, tuning: Tuning): Double {
         val enemy = other(seat)
 
         if (state.phase == BackgammonPhase.GAME_OVER) {
@@ -135,6 +205,8 @@ class BackgammonAi(private val level: BackgammonLevel? = null) :
         score -= state.off[enemy] * BORNE_OFF
         score -= state.bar[seat] * ON_BAR
         score += state.bar[enemy] * ON_BAR
+        // A gambler and a spoiler both like having an opponent on the bar.
+        score += state.bar[enemy] * (tuning.bold * 4.0 + tuning.spite * 8.0)
 
         for (point in 0 until POINTS) {
             val mine = state.countOn(point, seat)
@@ -142,6 +214,8 @@ class BackgammonAi(private val level: BackgammonLevel? = null) :
 
             if (mine >= 2) {
                 score += POINT_MADE
+                // A cautious seat likes covered points a little more, a gambler less.
+                score -= tuning.bold * 1.5
                 // A point in your own home board is a door shut in the face of
                 // anyone you send to the bar.
                 if (point in homeOf(seat)) score += HOME_POINT
@@ -151,7 +225,7 @@ class BackgammonAi(private val level: BackgammonLevel? = null) :
                 // A blot, weighted by how easily it can be reached: something
                 // six away is in real danger, something twenty away is not.
                 val distance = shortestEnemyDistance(state, seat, point)
-                score -= when {
+                score -= tuning.blot * when {
                     distance <= 0 -> 0.0
                     distance <= 6 -> BLOT_NEAR
                     distance <= 12 -> BLOT_FAR
@@ -160,7 +234,7 @@ class BackgammonAi(private val level: BackgammonLevel? = null) :
             }
         }
 
-        score += primeLength(state, seat) * PRIME
+        score += primeLength(state, seat) * (PRIME + tuning.spite * 3.0)
         return score
     }
 
@@ -199,6 +273,8 @@ class BackgammonAi(private val level: BackgammonLevel? = null) :
 
     private companion object {
         const val WIN = 10_000.0
+        const val FINALISTS = 8
+        val NEUTRAL = Tuning(1.0, 0.0, 0.0)
 
         const val PIP = 1.0
         const val BORNE_OFF = 12.0

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

@@ -1,5 +1,8 @@
 package org.prolibertate.games.game.catan
 
+import org.prolibertate.games.game.engine.AiLevel
+import org.prolibertate.games.game.engine.AiProfile
+import org.prolibertate.games.game.engine.AiProfiles
 import org.prolibertate.games.game.engine.GameAi
 
 /**
@@ -17,39 +20,48 @@ import org.prolibertate.games.game.engine.GameAi
  * dev-card counts, knights played — plus its own hand, and never looks
  * into the deck, another seat's development cards, or the seed beyond the
  * roll the rules derive from it.
+ *
+ * Each seat's [AiProfiles] entry shapes how it plays. The default profile
+ * (medium, balanced) is the AI described above. Easy settles for worse
+ * spots, trades and builds, now and then ends its turn early, and takes
+ * slightly bad trades. Hard weighs setup spots by balance and port synergy,
+ * values cards by what its next build is missing, races for Longest Road,
+ * keeps the robber off its own hexes and off the table's non-leaders, and
+ * is choosier about whom it trades with. Style nudges the tradeoffs: bold
+ * seats expand, cautious seats spend down before a seven can bite, spiteful
+ * seats go after the leader.
  */
-class CatanAi : GameAi<CatanState, CatanMove> {
+class CatanAi(private val profiles: AiProfiles = AiProfiles.DEFAULT) : GameAi<CatanState, CatanMove> {
 
     /** Plays the Cities & Knights tables; this class keeps the base game. */
-    private val ck = CatanCkAi(this)
+    private val ck = CatanCkAi(this, profiles)
 
     override fun chooseMove(state: CatanState, seat: Int, legal: List<CatanMove>): CatanMove {
+        val profile = profiles.of(seat)
         require(legal.isNotEmpty() || state.phase == CatanPhase.PLAYING) {
             "No legal move for seat $seat"
         }
         if (state.isCk) return ck.choose(state, seat, legal)
         return when (state.phase) {
             CatanPhase.SETUP_FIRST, CatanPhase.SETUP_SECOND ->
-                chooseSetup(state, seat, legal.filterIsInstance<SetupPlace>())
+                chooseSetup(state, seat, legal.filterIsInstance<SetupPlace>(), profile)
 
             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.GOLD -> chooseGold(state, seat, legal, profile)
 
-            CatanPhase.DISCARDING -> chooseDiscard(state, seat, legal.filterIsInstance<Discard>())
+            CatanPhase.DISCARDING -> chooseDiscard(state, seat, legal.filterIsInstance<Discard>(), profile)
 
-            CatanPhase.ROBBER -> chooseRobber(state, seat, legal.filterIsInstance<MoveRobber>())
+            CatanPhase.ROBBER -> chooseRobber(state, seat, legal.filterIsInstance<MoveRobber>(), profile)
 
-            CatanPhase.FREE_ROADS -> chooseFreeRoad(state, seat, legal)
+            CatanPhase.FREE_ROADS -> chooseFreeRoad(state, seat, legal, profile)
 
-            CatanPhase.TRADE_PENDING -> chooseResponse(state, seat, legal)
+            CatanPhase.TRADE_PENDING -> chooseResponse(state, seat, legal, profile)
 
-            CatanPhase.TRADE_COUNTERS -> chooseCounter(state, legal)
+            CatanPhase.TRADE_COUNTERS -> chooseCounter(state, seat, legal, profile)
 
-            CatanPhase.PLAYING -> choosePlaying(state, seat, legal)
+            CatanPhase.PLAYING -> choosePlaying(state, seat, legal, profile)
 
             CatanPhase.CHORE, CatanPhase.GAME_OVER -> legal.firstOrNull()
                 ?: error("Nothing to choose in phase ${state.phase}")
@@ -60,12 +72,68 @@ class CatanAi : GameAi<CatanState, CatanMove> {
     // Setup
     // -----------------------------------------------------------------------
 
-    internal fun chooseSetup(state: CatanState, seat: Int, places: List<SetupPlace>): SetupPlace {
+    internal fun chooseSetup(
+        state: CatanState,
+        seat: Int,
+        places: List<SetupPlace>,
+        profile: AiProfile = AiProfile.DEFAULT,
+    ): SetupPlace {
         require(places.isNotEmpty()) { "No legal settlement placement" }
-        return places.maxByOrNull { place ->
-            spotValue(state, place.vertex) +
-                0.25 * placeDirection(state, place)
-        } ?: places.first()
+        // A bold seat cares more where its road leads; a cautious one less.
+        val direction = 0.25 + 0.1 * profile.style.boldness
+        return when (profile.level) {
+            // Easy looks only at the spot itself, and sometimes settles for the runner-up.
+            AiLevel.EASY -> profile.pick(places.sortedByDescending { spotValue(state, it.vertex) })
+
+            AiLevel.HARD -> places.maxByOrNull { place ->
+                hardSpot(state, seat, place.vertex) + direction * placeDirection(state, place)
+            } ?: places.first()
+
+            AiLevel.MEDIUM -> places.maxByOrNull { place ->
+                spotValue(state, place.vertex) + direction * placeDirection(state, place)
+            } ?: places.first()
+        }
+    }
+
+    /**
+     * A spot as a seat that plans would see it: the plain production value,
+     * plus resources the seat does not yet draw, less piling onto one it
+     * already has plenty of, and ports worth what the seat will produce to
+     * trade through them.
+     */
+    internal fun hardSpot(state: CatanState, seat: Int, vertex: Int): Double {
+        if (state.buildings[vertex] != null) return -1.0
+        val topo = state.topo
+        val owned = HashMap<Resource, Double>()
+        for (v in state.buildings.indices) {
+            val b = state.buildings[v] ?: continue
+            if (b.owner != seat) continue
+            val mult = if (b.type == BuildingType.CITY) 2.0 else 1.0
+            for (h in topo.VERTEX_HEXES[v]) {
+                val res = state.terrains[h].produces ?: continue
+                owned[res] = (owned[res] ?: 0.0) + mult * CatanBoard.numberOdds(state.numbers[h]) / 36.0
+            }
+        }
+        val here = HashMap<Resource, Double>()
+        for (h in topo.VERTEX_HEXES[vertex]) {
+            val res = state.terrains[h].produces ?: continue
+            here[res] = (here[res] ?: 0.0) + CatanBoard.numberOdds(state.numbers[h]) / 36.0
+        }
+        var value = spotValue(state, vertex)
+        value += 0.15 * here.keys.count { (owned[it] ?: 0.0) <= 0.0 }
+        for ((res, p) in here) {
+            if ((owned[res] ?: 0.0) > 0.15) value -= 0.3 * p
+        }
+        val total = owned.values.sum() + here.values.sum()
+        for (e in topo.VERTEX_EDGES[vertex]) {
+            val port = state.ports.firstOrNull { it.edge == e } ?: continue
+            value += if (port.resource == null) {
+                0.05 + 0.15 * total
+            } else {
+                0.9 * ((owned[port.resource] ?: 0.0) + (here[port.resource] ?: 0.0))
+            }
+        }
+        return value
     }
 
     /**
@@ -87,48 +155,132 @@ class CatanAi : GameAi<CatanState, CatanMove> {
     // Dice, discards and the robber
     // -----------------------------------------------------------------------
 
-    private fun chooseDiscard(state: CatanState, seat: Int, discards: List<Discard>): Discard {
+    private fun chooseDiscard(
+        state: CatanState,
+        seat: Int,
+        discards: List<Discard>,
+        profile: AiProfile,
+    ): Discard {
         require(discards.isNotEmpty()) { "No legal discard" }
         // Throw away what it wants least; grain and ore are the city, wool
         // is mostly a dev-card tax.
-        return discards.minByOrNull { discard ->
-            discard.cards.sumOf { want(it) }
-        } ?: discards.first()
+        return when (profile.level) {
+            AiLevel.EASY -> profile.pick(discards.sortedBy { d -> d.cards.sumOf { want(it) } })
+
+            // Keep the hand that is closest to paying for something.
+            AiLevel.HARD -> {
+                val hand = state.resources[seat]
+                discards.maxByOrNull { d ->
+                    val left = hand.toMutableMap()
+                    for (c in d.cards) left[c] = (left[c] ?: 0) - 1
+                    progress(left) - 0.01 * d.cards.sumOf { want(it) }
+                } ?: discards.first()
+            }
+
+            AiLevel.MEDIUM -> discards.minByOrNull { discard ->
+                discard.cards.sumOf { want(it) }
+            } ?: discards.first()
+        }
     }
 
-    private fun chooseRobber(state: CatanState, seat: Int, moves: List<MoveRobber>): MoveRobber {
+    /** How close a hand is to the nearest of the things worth buying, a card count over a price, plus one if it pays. */
+    private fun progress(hand: Map<Resource, Int>): Double = SHOPPING.maxOf { cost ->
+        val have = cost.entries.sumOf { (r, n) -> minOf(maxOf(hand[r] ?: 0, 0), n) }
+        have.toDouble() / cost.values.sum() + if (covers(hand, cost)) 1.0 else 0.0
+    }
+
+    internal fun chooseGold(state: CatanState, seat: Int, legal: List<CatanMove>, profile: AiProfile): CatanMove {
+        val picks = legal.filterIsInstance<PickGold>()
+        if (picks.isEmpty()) return legal.first()
+        return when (profile.level) {
+            AiLevel.EASY -> profile.pick(picks.sortedByDescending { p -> p.cards.sumOf { want(it) } })
+            AiLevel.HARD -> picks.maxByOrNull { p -> p.cards.sumOf { need(state, seat, it) } } ?: picks.first()
+            AiLevel.MEDIUM -> picks.maxByOrNull { pick -> pick.cards.sumOf { want(it) } } ?: legal.first()
+        }
+    }
+
+    private fun chooseRobber(
+        state: CatanState,
+        seat: Int,
+        moves: List<MoveRobber>,
+        profile: AiProfile,
+    ): MoveRobber {
         require(moves.isNotEmpty()) { "No legal robber move" }
         val points = CatanRules.publicVictoryPoints(state)
-        return moves.maxByOrNull { move ->
+        val hard = profile.level == AiLevel.HARD
+        val spite = profile.style.spite
+        val leader = (0 until state.playerCount).filter { it != seat }.maxByOrNull { points[it] }
+        val victimWeight = 0.3 + 0.1 * profile.style.boldness
+        fun score(move: MoveRobber): Double {
             val hex = state.topo.hexIndex.getValue(move.hex)
             var score = 0.0
             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
-                score += worth * CatanBoard.numberOdds(state.numbers[hex]) / 36.0
+                val raw = worth * CatanBoard.numberOdds(state.numbers[hex])
+                if (building.owner == seat) {
+                    // A hard seat will not sit the robber on its own income.
+                    if (hard) score -= 0.8 * raw / 36.0
+                    continue
+                }
+                score += raw / 36.0
+                if (building.owner == leader) score += spite * raw / 36.0
             }
             if (move.victim != null) {
-                score += 0.15 * state.resourceCount(move.victim) +
-                    0.3 * points[move.victim]
+                val cards = state.resourceCount(move.victim)
+                if (!hard || cards > 0) {
+                    score += 0.15 * cards + victimWeight * points[move.victim]
+                    if (move.victim == leader) score += 0.4 * spite
+                }
             }
-            score
-        } ?: moves.first()
+            return score
+        }
+        return if (profile.level == AiLevel.EASY) {
+            profile.pick(moves.sortedByDescending { score(it) })
+        } else {
+            moves.maxByOrNull { score(it) } ?: moves.first()
+        }
     }
 
     // -----------------------------------------------------------------------
     // The main phase
     // -----------------------------------------------------------------------
 
-    private fun choosePlaying(state: CatanState, seat: Int, legal: List<CatanMove>): CatanMove {
-        // A city doubles the best production the seat already owns.
-        legal.filterIsInstance<BuildCity>().maxByOrNull {
-            spotValue(state, it.vertex)
-        }?.let { return it }
+    private fun choosePlaying(state: CatanState, seat: Int, legal: List<CatanMove>, profile: AiProfile): CatanMove {
+        val easy = profile.level == AiLevel.EASY
+        val hard = profile.level == AiLevel.HARD
+        val boldness = profile.style.boldness
+        val endTurn = legal.lastOrNull { it is EndTurn } ?: legal.first()
 
-        legal.filterIsInstance<BuildSettlement>().maxByOrNull {
-            spotValue(state, it.vertex)
-        }?.let { return it }
+        // Easy loses the thread now and then and just passes.
+        if (easy && profile.slips() && profile.random.nextBoolean()) return endTurn
+
+        val cities = legal.filterIsInstance<BuildCity>()
+        val settlements = legal.filterIsInstance<BuildSettlement>()
+        if (hard && (cities.isNotEmpty() || settlements.isNotEmpty())) {
+            // A city doubles what the seat has; a settlement spreads it and
+            // takes a spot nobody else will. Bold seats lean to the spread.
+            val city = cities.maxByOrNull { spotValue(state, it.vertex) }
+            val settlement = settlements.maxByOrNull { hardSpot(state, seat, it.vertex) }
+            val cityScore = if (city != null) spotValue(state, city.vertex) + 0.15 else Double.NEGATIVE_INFINITY
+            val settleScore = if (settlement != null) {
+                hardSpot(state, seat, settlement.vertex) + 0.3 + 0.1 * boldness
+            } else {
+                Double.NEGATIVE_INFINITY
+            }
+            if (city != null && cityScore >= settleScore) return city
+            if (settlement != null) return settlement
+        } else {
+            // A city doubles the best production the seat already owns.
+            pickBest(cities, profile) { spotValue(state, it.vertex) }?.let { return it }
+
+            pickBest(settlements, profile) { spotValue(state, it.vertex) }?.let { return it }
+        }
+
+        // A raid on a fortress, or the next stage of a wonder, beats a card.
+        legal.filterIsInstance<RaidFortress>().firstOrNull()?.let { return it }
+        legal.filterIsInstance<DigCanal>().firstOrNull()?.let { return it }
+        legal.filterIsInstance<BuildWonder>().firstOrNull()?.let { return it }
 
         // Seafarers: a ship toward an island nobody has landed on is worth more than a card.
         legal.filterIsInstance<BuildShip>()
@@ -138,11 +290,15 @@ class CatanAi : GameAi<CatanState, CatanMove> {
 
         // 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 }
+        if (!(easy && profile.slips())) {
+            legal.filterIsInstance<PlayKnight>().firstOrNull()?.let { return it }
+        }
 
-        yearOfPlenty(state, legal)?.let { return it }
+        if (!(easy && profile.slips())) {
+            yearOfPlenty(state, seat, legal, profile)?.let { return it }
 
-        monopoly(state, legal)?.let { return it }
+            monopoly(state, legal)?.let { return it }
+        }
 
         // Road Building is worth two free segments whenever there is
         // somewhere to put them.
@@ -152,6 +308,14 @@ class CatanAi : GameAi<CatanState, CatanMove> {
             return legal.filterIsInstance<PlayRoadBuilding>().first()
         }
 
+        // Hard seat in a Longest Road race puts the road down before spending on cards.
+        val roadThreshold = 0.1 - 0.04 * boldness
+        if (hard && roadRace(state, seat)) {
+            legal.filterIsInstance<BuildRoad>()
+                .maxByOrNull { roadValue(state, it) }
+                ?.let { return it }
+        }
+
         legal.filterIsInstance<BuyDevCard>().firstOrNull()?.let { return it }
 
         // Seafarers: a ship that heads for a settlement spot worth having.
@@ -162,7 +326,7 @@ class CatanAi : GameAi<CatanState, CatanMove> {
 
         // A paid road only when it reaches toward a spot worth settling.
         legal.filterIsInstance<BuildRoad>()
-            .filter { roadValue(state, it) > 0.1 }
+            .filter { roadValue(state, it) > roadThreshold }
             .maxByOrNull { roadValue(state, it) }
             ?.let { return it }
 
@@ -173,16 +337,94 @@ class CatanAi : GameAi<CatanState, CatanMove> {
             .maxByOrNull { CatanRules.bestPortRatio(state, seat, it.give) * -1.0 }
             ?.let { return it }
 
-        offer(state, seat)?.let { return it }
+        if (hard) {
+            // Pile of one card, short of another: convert before it is stuck in hand.
+            legal.filterIsInstance<MaritimeTrade>()
+                .filter { surplusTrade(state, seat, it) }
+                .minByOrNull { CatanRules.bestPortRatio(state, seat, it.give) }
+                ?.let { return it }
+        }
 
-        return legal.lastOrNull { it is EndTurn } ?: legal.first()
+        // Stay under the seven: a cautious (or careful) seat sells down a big hand.
+        if ((hard || boldness < 0) && state.resourceCount(seat) > DISCARD_LIMIT) {
+            legal.filterIsInstance<MaritimeTrade>()
+                .maxByOrNull { t ->
+                    (state.resources[seat][t.give] ?: 0) * 10.0 -
+                        CatanRules.bestPortRatio(state, seat, t.give) * 3.0 + need(state, seat, t.get)
+                }
+                ?.let { return it }
+        }
+
+        if (!(easy && profile.slips())) {
+            offer(state, seat, profile)?.let { return it }
+        }
+
+        return endTurn
+    }
+
+    /** Picks the best of [items] by [score]; easy sometimes takes a near miss. */
+    private fun <T> pickBest(items: List<T>, profile: AiProfile, score: (T) -> Double): T? {
+        if (items.isEmpty()) return null
+        if (profile.level != AiLevel.EASY) return items.maxByOrNull(score)
+        return profile.pick(items.sortedByDescending(score))
+    }
+
+    /** The cheapest things worth saving for, as the shopping list a hard seat weighs hands against. */
+    private val SHOPPING = listOf(
+        CatanRules.CITY_COST,
+        CatanRules.SETTLEMENT_COST,
+        CatanRules.DEV_COST,
+        CatanRules.ROAD_COST,
+    )
+
+    /** The shopping list entry the hand is closest to paying for, among a city, a settlement and a card. */
+    private fun nearestTarget(hand: Map<Resource, Int>): Map<Resource, Int> =
+        listOf(CatanRules.CITY_COST, CatanRules.SETTLEMENT_COST, CatanRules.DEV_COST)
+            .minByOrNull { cost -> cost.entries.sumOf { (r, n) -> maxOf(0, n - (hand[r] ?: 0)) } }
+            ?: CatanRules.CITY_COST
+
+    /** What one card of [res] is worth to this seat right now: more if the next build lacks it, less if it is piled up. */
+    private fun need(state: CatanState, seat: Int, res: Resource): Double {
+        val hand = state.resources[seat]
+        var v = want(res)
+        if ((hand[res] ?: 0) < (nearestTarget(hand)[res] ?: 0)) v += 0.6
+        if ((hand[res] ?: 0) >= 4) v -= 0.4
+        return v
+    }
+
+    /** Whether this bank trade turns a pile (beyond any price) into a card the next build lacks. */
+    private fun surplusTrade(state: CatanState, seat: Int, move: MaritimeTrade): Boolean {
+        val hand = state.resources[seat]
+        val ratio = CatanRules.bestPortRatio(state, seat, move.give)
+        val keep = SHOPPING.maxOf { it[move.give] ?: 0 }
+        val target = nearestTarget(hand)
+        return (hand[move.give] ?: 0) - keep >= ratio &&
+            (hand[move.get] ?: 0) < (target[move.get] ?: 0)
+    }
+
+    /** Whether [seat] is in the hunt for Longest Road: close enough to the holder, or the road is unclaimed. */
+    private fun roadRace(state: CatanState, seat: Int): Boolean {
+        val holder = state.longestRoadOwner
+        if (holder == seat) return false
+        val mine = CatanRules.longestRoadFor(state, seat)
+        if (mine < 3) return false
+        return holder == null || mine + 1 >= CatanRules.longestRoadFor(state, holder)
+    }
+
+    /** The opponent with the most public points, if any. */
+    private fun leaderOf(state: CatanState, seat: Int): Int? {
+        val points = CatanRules.publicVictoryPoints(state)
+        return (0 until state.playerCount).filter { it != seat }.maxByOrNull { points[it] }
     }
 
     /** Year of Plenty: two of whatever the nearest build is shortest of. */
-    private fun yearOfPlenty(state: CatanState, legal: List<CatanMove>): PlayYearOfPlenty? {
+    private fun yearOfPlenty(state: CatanState, seat: Int, legal: List<CatanMove>, profile: AiProfile): PlayYearOfPlenty? {
         val takes = legal.filterIsInstance<PlayYearOfPlenty>()
         if (takes.isEmpty()) return null
         val shortage = shortage(state) ?: return null
+        if (profile.level == AiLevel.HARD) {
+            return takes.maxByOrNull { take -> take.take.sumOf { need(state, seat, it) } }
+        }
         return takes.maxByOrNull { take ->
             take.take.count { it == shortage } * 2 + take.take.size
         }
@@ -234,7 +476,7 @@ class CatanAi : GameAi<CatanState, CatanMove> {
      * At most one offer a turn: a declined offer changes nothing, so
      * re-offering it would only bounce between the same two seats forever.
      */
-    private fun offer(state: CatanState, seat: Int): OfferTrade? {
+    private fun offer(state: CatanState, seat: Int, profile: AiProfile): OfferTrade? {
         if (offeredThisTurn(state, seat)) return null
         val seatHand = state.resources[seat]
         val builds = listOf(CatanRules.CITY_COST, CatanRules.SETTLEMENT_COST)
@@ -247,11 +489,16 @@ class CatanAi : GameAi<CatanState, CatanMove> {
                 .filter { (seatHand[it] ?: 0) > (cost[it] ?: 0) }
                 .sortedByDescending { seatHand[it] ?: 0 }
             if (surplus.isEmpty()) continue
-            val target = (0 until state.playerCount)
+            val holders = (0 until state.playerCount)
                 .filter { it != seat }
                 .filter { (state.resources[it][need] ?: 0) > 0 }
-                .maxByOrNull { state.resources[it][need] ?: 0 }
-                ?: continue
+            val target = (if (profile.level == AiLevel.HARD) {
+                // Do not feed the leader when someone else can make the swap.
+                val points = CatanRules.publicVictoryPoints(state)
+                holders.maxByOrNull { (state.resources[it][need] ?: 0) - 0.5 * points[it] }
+            } else {
+                holders.maxByOrNull { state.resources[it][need] ?: 0 }
+            }) ?: continue
             val give = listOf(surplus.first(), surplus.first())
             val trade = OfferTrade(to = target, give = give, get = listOf(need))
             if (CatanRules.isLegalMove(state, seat, trade)) return trade
@@ -274,38 +521,73 @@ class CatanAi : GameAi<CatanState, CatanMove> {
     // Free roads and trade responses
     // -----------------------------------------------------------------------
 
-    private fun chooseFreeRoad(state: CatanState, seat: Int, legal: List<CatanMove>): CatanMove {
-        val roads = legal.filterIsInstance<BuildRoad>()
-            .filter { roadValue(state, it) > 0.05 }
-            .maxByOrNull { roadValue(state, it) }
-        return roads ?: legal.firstOrNull { it is EndFreeRoads }
-            ?: legal.filterIsInstance<BuildRoad>().firstOrNull()
-            ?: legal.first()
+    private fun chooseFreeRoad(state: CatanState, seat: Int, legal: List<CatanMove>, profile: AiProfile): CatanMove {
+        val roads = legal.filterIsInstance<BuildRoad>().filter { roadValue(state, it) > 0.05 }
+        val road = if (profile.level == AiLevel.EASY) {
+            profile.pick(roads.sortedByDescending { roadValue(state, it) }.ifEmpty { return freeRoadFallback(legal) })
+        } else {
+            roads.maxByOrNull { roadValue(state, it) }
+        }
+        return road ?: freeRoadFallback(legal)
     }
 
-    private fun chooseResponse(state: CatanState, seat: Int, legal: List<CatanMove>): CatanMove {
+    private fun freeRoadFallback(legal: List<CatanMove>): CatanMove =
+        legal.firstOrNull { it is EndFreeRoads }
+            ?: legal.filterIsInstance<BuildRoad>().firstOrNull()
+            ?: legal.first()
+
+    /**
+     * How much extra the incoming cards must be worth to take a swap: nothing
+     * for the standard seat, a hard or spiteful seat wants more from the
+     * table's leader, and an easy seat is not too fussy.
+     */
+    private fun tradeMargin(state: CatanState, seat: Int, other: Int, profile: AiProfile): Double {
+        var margin = 0.0
+        if (profile.level == AiLevel.EASY) margin -= 0.6
+        val leader = leaderOf(state, seat)
+        if (leader != null && other == leader) {
+            if (profile.level == AiLevel.HARD) margin += 0.4
+            margin += 0.5 * profile.style.spite
+        }
+        return margin
+    }
+
+    private fun tradeValue(state: CatanState, seat: Int, res: Resource, profile: AiProfile): Double =
+        if (profile.level == AiLevel.HARD) need(state, seat, res) else want(res)
+
+    private fun chooseResponse(state: CatanState, seat: Int, legal: List<CatanMove>, profile: AiProfile): CatanMove {
         val accept = legal.filterIsInstance<AcceptTrade>().firstOrNull()
         val offer = state.pendingTrade
         if (accept == null || offer == null) return legal.first { it is DeclineTrade }
         // Accept when what arrives (the offerer's give) is worth more than what
         // leaves (the offerer's get): a mild table, not a shark.
-        val incoming = offer.give.sumOf { want(it) }
-        val outgoing = offer.get.sumOf { want(it) }
-        return if (incoming > outgoing) accept else legal.first { it is DeclineTrade }
+        val incoming = offer.give.sumOf { tradeValue(state, seat, it, profile) }
+        val outgoing = offer.get.sumOf { tradeValue(state, seat, it, profile) }
+        return if (incoming > outgoing + tradeMargin(state, seat, offer.by, profile)) {
+            accept
+        } else {
+            legal.first { it is DeclineTrade }
+        }
     }
 
     /**
      * Picks the counter-offer that gains the most by the same valuation, or
      * turns them all down. The AI never counters itself: it only answers.
      */
-    private fun chooseCounter(state: CatanState, legal: List<CatanMove>): CatanMove {
+    private fun chooseCounter(state: CatanState, seat: Int, legal: List<CatanMove>, profile: AiProfile): CatanMove {
         val offer = state.pendingTrade ?: return legal.first()
+        fun gain(c: TradeCounter) = c.give.sumOf { tradeValue(state, seat, it, profile) } -
+            c.get.sumOf { tradeValue(state, seat, it, profile) }
         val best = legal.filterIsInstance<AcceptCounter>()
             .map { choice -> choice to offer.counters.first { it.by == choice.seat } }
-            .maxByOrNull { (_, c) -> c.give.sumOf { want(it) } - c.get.sumOf { want(it) } }
+            .maxByOrNull { (_, c) -> gain(c) }
         if (best != null) {
             val (choice, c) = best
-            if (c.give.sumOf { want(it) } > c.get.sumOf { want(it) }) return choice
+            if (c.give.sumOf { tradeValue(state, seat, it, profile) } >
+                c.get.sumOf { tradeValue(state, seat, it, profile) } + tradeMargin(state, seat, c.by, profile)
+            ) {
+                return choice
+            }
         }
         return legal.first { it is DismissCounters }
     }
@@ -315,6 +597,26 @@ class CatanAi : GameAi<CatanState, CatanMove> {
     // -----------------------------------------------------------------------
 
     /** What a seat would think of building on [vertex]: production and ports. */
+    /** What a spot beside a cloth village or an unclaimed tribe chip is worth beyond its cards. */
+    private fun scenarioLure(state: CatanState, vertex: Int): Double {
+        // The Harbormaster: a town on a harbour is a point toward a title worth two.
+        if (CatanRules.harbormasterGame(state) &&
+            state.topo.VERTEX_EDGES[vertex].any { e -> state.ports.any { it.edge == e } }
+        ) return HARBOR_LURE
+        val sea = state.sea ?: return 0.0
+        var lure = 0.0
+        for (h in state.topo.VERTEX_HEXES[vertex]) {
+            // A cloth token is a quarter-point, rolled as often as its number comes up.
+            if (state.terrains[h] == Terrain.VILLAGE && sea.villageCloth.getOrElse(h) { 0 } > 0) {
+                lure += CatanBoard.numberOdds(state.numbers[h]) / 36.0 * CLOTH_WORTH
+            }
+            // An unfinished canal tile is a place to dig: points now, grain land later.
+            if (sea.canalNumbers.getOrElse(h) { 0 } != 0 && state.terrains[h] == Terrain.DESERT) lure += CANAL_LURE
+            if (sea.chips.getOrNull(h).let { it != null && it != TribeChip.NONE }) lure += CHIP_LURE
+        }
+        return lure
+    }
+
     internal fun spotValue(state: CatanState, vertex: Int): Double {
         if (state.buildings[vertex] != null) return -1.0
         var value = 0.0
@@ -325,6 +627,7 @@ class CatanAi : GameAi<CatanState, CatanMove> {
             kinds += resource
         }
         value += 0.12 * kinds.size // variety keeps a build plan alive
+        value += scenarioLure(state, 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
@@ -367,9 +670,16 @@ class CatanAi : GameAi<CatanState, CatanMove> {
             val next = mutableListOf<Int>()
             for (v in frontier) {
                 if (!seen.add(v)) continue
+                // Fog is worth a look: a card on arrival, and land to settle that nobody has seen.
+                if (topo.VERTEX_HEXES[v].any { state.terrains[it] == Terrain.FOG }) best = maxOf(best, FOG_LURE * Math.pow(0.85, depth.toDouble()))
+                // A fortress is worth a raid once a ship lies beside it.
+                if (sea.fortress.isNotEmpty() && topo.VERTEX_EDGES[v].any { e ->
+                        topo.edgeSea[e] && topo.EDGE_HEXES[e].any { sea.fortress.getOrElse(it) { 0 } > 0 }
+                    }
+                ) best = maxOf(best, FORT_LURE * Math.pow(0.85, depth.toDouble()))
                 if (CatanRules.vertexOpenForSettlement(state, v)) {
                     val island = topo.vertexIsland[v]
-                    val fresh = island >= 0 && island != sea.home && sea.islandBonus[island] == NO_PLAYER
+                    val fresh = island >= 0 && !sea.isStart(island) && 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)
                 }
@@ -392,4 +702,17 @@ class CatanAi : GameAi<CatanState, CatanMove> {
         Resource.BRICK -> 0.95
         Resource.WOOL -> 0.85 // abundant and only half of a dev card
     }
+
+    private companion object {
+        /** A seven makes a seat holding more than this discard half. */
+        const val DISCARD_LIMIT = 7
+
+        /** What a ship end beside undiscovered land is worth, on the scale of [spotValue]. */
+        const val FOG_LURE = 0.6
+        const val FORT_LURE = 1.2
+        const val CLOTH_WORTH = 2.5
+        const val CHIP_LURE = 0.5
+        const val CANAL_LURE = 0.6
+        const val HARBOR_LURE = 0.5
+    }
 }

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

@@ -429,6 +429,9 @@ object CatanBoard {
      * tokens go to four of the six board-corner hexes, which are pairwise
      * non-adjacent, and at most one corner can be desert.
      */
+    /** The seed of the First Island scenario's fixed layout. */
+    const val FIRST_ISLAND_SEED = 1L
+
     fun generate(seed: Long): Generated {
         val random = Random(seed)
         val terrains = TERRAIN_TILES.shuffled(random)

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

@@ -171,18 +171,22 @@ object CatanCk {
 
     /** Cities of [seat] that can carry a metropolis or fall to the barbarians' rival: all but metropolises. */
     private fun plainCities(state: CatanState, seat: Int): List<Int> =
-        (0 until CatanBoard.VERTEX_COUNT).filter { v ->
+        (0 until state.topo.VERTEX_COUNT).filter { v ->
             state.buildings[v] == CatanBuilding(BuildingType.CITY, seat) && !hasMetropolis(state, v)
         }
 
     private fun ownsCity(state: CatanState, seat: Int): Boolean =
         state.buildings.any { it == CatanBuilding(BuildingType.CITY, seat) }
 
-    /** Empty crossings at the end of one of [seat]'s roads: where a knight can be put. */
+    /** Whether [seat] has a road, or a ship in Seafarers, on [edge]: the network a knight moves along. */
+    private fun holds(state: CatanState, seat: Int, edge: Int): Boolean =
+        state.roads[edge] == seat || state.sea?.ships?.get(edge) == seat
+
+    /** Empty crossings at the end of one of [seat]'s roads or ships on land: where a knight can be put. */
     private fun knightSpots(state: CatanState, seat: Int): List<Int> =
-        (0 until CatanBoard.VERTEX_COUNT).filter { v ->
-            state.buildings[v] == null && knightAt(state, v) == null &&
-                CatanBoard.VERTEX_EDGES[v].any { state.roads[it] == seat }
+        (0 until state.topo.VERTEX_COUNT).filter { v ->
+            state.topo.vertexLand[v] && state.buildings[v] == null && knightAt(state, v) == null &&
+                state.topo.VERTEX_EDGES[v].any { holds(state, seat, it) }
         }
 
     /**
@@ -196,9 +200,9 @@ object CatanCk {
         val queue = ArrayDeque<Int>().apply { add(from) }
         while (queue.isNotEmpty()) {
             val v = queue.removeFirst()
-            for (e in CatanBoard.VERTEX_EDGES[v]) {
-                if (state.roads[e] != seat) continue
-                val w = CatanBoard.otherEnd(e, v)
+            for (e in state.topo.VERTEX_EDGES[v]) {
+                if (!holds(state, seat, e)) continue
+                val w = state.topo.otherEnd(e, v)
                 if (!seen.add(w)) continue
                 val building = state.buildings[w]
                 val knight = knightAt(state, w)
@@ -215,14 +219,14 @@ object CatanCk {
     private fun destinations(state: CatanState, k: Knight): List<Int> =
         walk(state, k.owner, k.vertex).filter { w ->
             val there = knightAt(state, w)
-            if (state.buildings[w] != null) return@filter false
+            if (state.buildings[w] != null || !state.topo.vertexLand[w]) return@filter false
             there == null || (there.owner != k.owner && there.level < k.level)
         }.sorted()
 
     /** Empty crossings a driven-off [knight] of its owner could still reach. */
     private fun refuges(state: CatanState, knight: Knight): List<Int> =
         walk(state, knight.owner, knight.vertex).filter { w ->
-            state.buildings[w] == null && knightAt(state, w) == null
+            state.buildings[w] == null && state.topo.vertexLand[w] && knightAt(state, w) == null
         }.sorted()
 
     private fun promotable(state: CatanState, k: Knight): Boolean {
@@ -251,6 +255,8 @@ object CatanCk {
             points[seat] += ck.defenderVp[seat] + ck.progressVp[seat]
         }
         ck.merchant?.let { points[it.seat] += 1 }
+        state.harbormaster?.let { points[it] += CatanRules.HARBORMASTER_POINTS }
+        if (state.isSea) for (seat in points.indices) points[seat] += SeaRules.bonusPoints(state, seat)
         return points.toList()
     }
 
@@ -266,15 +272,18 @@ object CatanCk {
             addAll(actionMoves(state, seat))
         }
 
-        CatanPhase.ROBBER -> robberMoves(state, seat)
+        // The bishop moves the robber alone; a seven may send the pirate instead.
+        CatanPhase.ROBBER -> robberMoves(state, seat) +
+            (if (state.isSea && !state.ck!!.bishop) SeaRules.pirateMoves(state, seat) else emptyList())
 
         CatanPhase.PLAYING -> playingMoves(state, seat)
 
         CatanPhase.FREE_ROADS ->
-            CatanRules.roadMoves(state, seat) + listOf<CatanMove>(EndFreeRoads)
+            CatanRules.roadMoves(state, seat) +
+                (if (state.isSea) SeaRules.buildShipMoves(state, seat) else emptyList()) +
+                listOf<CatanMove>(EndFreeRoads)
 
-        // Seafarers is never combined with Cities & Knights.
-        CatanPhase.GOLD -> emptyList()
+        CatanPhase.GOLD -> SeaRules.goldMoves(state)
 
         CatanPhase.TRADE_PENDING -> {
             val offer = state.ck!!.goodsOffer
@@ -327,7 +336,7 @@ object CatanCk {
             if (!k.active && affordable(state, seat, ACTIVATE_COST)) moves += ActivateKnight(k.vertex)
             if (canAct(state, k)) {
                 destinations(state, k).forEach { moves += MoveKnight(k.vertex, it) }
-                if (ck.attacked && k.vertex in CatanBoard.HEX_CORNERS[state.robber]) {
+                if (ck.attacked && k.vertex in state.topo.HEX_CORNERS[state.robber]) {
                     moves += ChaseRobber(k.vertex)
                 }
             }
@@ -340,6 +349,11 @@ object CatanCk {
         val moves = mutableListOf<CatanMove>()
 
         if (affordable(state, seat, CatanRules.ROAD_COST)) moves += CatanRules.roadMoves(state, seat)
+        if (state.isSea) {
+            if (affordable(state, seat, SeaRules.SHIP_COST)) moves += SeaRules.buildShipMoves(state, seat)
+            moves += SeaRules.moveShipMoves(state, seat)
+            moves += SeaRules.scenarioMoves(state, seat)
+        }
         if (affordable(state, seat, CatanRules.SETTLEMENT_COST)) {
             moves += CatanRules.settlementVertices(state, seat).map { BuildSettlement(it) }
         }
@@ -380,7 +394,7 @@ object CatanCk {
     /** Own cities with no wall, while the seat has a wall left to build. */
     private fun wallSites(state: CatanState, seat: Int): List<Int> {
         if (wallsOf(state, seat) >= MAX_WALLS) return emptyList()
-        return (0 until CatanBoard.VERTEX_COUNT).filter { v ->
+        return (0 until state.topo.VERTEX_COUNT).filter { v ->
             state.buildings[v] == CatanBuilding(BuildingType.CITY, seat) && v !in state.ck!!.walls
         }
     }
@@ -423,20 +437,37 @@ object CatanCk {
     private fun robberMoves(state: CatanState, seat: Int): List<MoveRobber> {
         val bishop = state.ck!!.bishop
         val moves = mutableListOf<MoveRobber>()
-        for (h in 0 until CatanBoard.HEX_COUNT) {
-            if (h == state.robber) continue
+        for (h in 0 until state.topo.HEX_COUNT) {
+            if (h == state.robber || !state.topo.land[h] || state.terrains[h] == Terrain.FOG) continue
             val victims = victimsAt(state, seat, h)
             when {
-                bishop -> moves += MoveRobber(CatanBoard.HEXES[h])
-                victims.isEmpty() -> moves += MoveRobber(CatanBoard.HEXES[h])
-                else -> victims.forEach { moves += MoveRobber(CatanBoard.HEXES[h], it) }
+                bishop -> moves += MoveRobber(state.topo.HEXES[h])
+                victims.isEmpty() -> moves += MoveRobber(state.topo.HEXES[h])
+                else -> victims.forEach { moves += MoveRobber(state.topo.HEXES[h], it) }
             }
         }
         return moves
     }
 
+    /** The pirate, sent by a seven once the barbarians have landed: it robs a seat with a ship beside it. */
+    fun applyPirate(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 stole = ""
+        val hand = move.victim?.let { goodsList(s, it) }.orEmpty()
+        if (move.victim != null && hand.isNotEmpty()) {
+            val card = hand[Random(state.seed * 1_000_003L + state.rngStep).nextInt(hand.size)]
+            s = give(s, move.victim, seat, listOf(card))
+            stole = " and takes a ${good(card)} from seat ${move.victim}"
+        }
+        return s.copy(
+            phase = if (state.ck!!.back == Back.AWAIT_ROLL) CatanPhase.AWAIT_ROLL else CatanPhase.PLAYING,
+            log = s.log + "Seat $seat sends the pirate to (${move.hex.q},${move.hex.r})$stole.",
+        )
+    }
+
     private fun victimsAt(state: CatanState, seat: Int, hex: Int): List<Int> =
-        CatanBoard.HEX_CORNERS[hex]
+        state.topo.HEX_CORNERS[hex]
             .mapNotNull { state.buildings[it] }
             .map { it.owner }
             .filter { it != seat }
@@ -445,7 +476,7 @@ object CatanCk {
 
     fun applyRobber(state: CatanState, seat: Int, move: MoveRobber): CatanState {
         val ck = state.ck!!
-        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)
         val rng = Random(state.seed * 1_000_003L + state.rngStep)
@@ -495,7 +526,7 @@ object CatanCk {
             ProgressType.ENGINEER -> wallSites(state, seat).map { PlayProgress(id, vertex = it) }
 
             ProgressType.INVENTOR -> {
-                val hexes = (0 until CatanBoard.HEX_COUNT).filter { state.numbers[it] in INVENTOR_NUMBERS }
+                val hexes = (0 until state.topo.HEX_COUNT).filter { state.numbers[it] in INVENTOR_NUMBERS }
                 hexes.flatMap { a ->
                     hexes.filter { b -> b > a && state.numbers[b] != state.numbers[a] }
                         .map { b -> PlayProgress(id, hexA = a, hexB = b) }
@@ -530,7 +561,7 @@ object CatanCk {
 
             ProgressType.INTRIGUE ->
                 ck.knights.filter { k ->
-                    k.owner != seat && CatanBoard.VERTEX_EDGES[k.vertex].any { state.roads[it] == seat }
+                    k.owner != seat && state.topo.VERTEX_EDGES[k.vertex].any { holds(state, seat, it) }
                 }.map { PlayProgress(id, vertex = it.vertex) }
 
             ProgressType.SABOTEUR -> listOf(PlayProgress(id))
@@ -559,9 +590,9 @@ object CatanCk {
                 }
 
             ProgressType.MERCHANT ->
-                (0 until CatanBoard.HEX_COUNT).filter { h ->
-                    state.terrains[h] != Terrain.DESERT &&
-                        CatanBoard.HEX_CORNERS[h].any { state.buildings[it]?.owner == seat }
+                (0 until state.topo.HEX_COUNT).filter { h ->
+                    state.terrains[h] != Terrain.DESERT && state.topo.land[h] && state.terrains[h] != Terrain.FOG &&
+                        state.topo.HEX_CORNERS[h].any { state.buildings[it]?.owner == seat }
                 }.map { PlayProgress(id, hexA = it) }
 
             ProgressType.MERCHANT_FLEET -> Good.entries.map { PlayProgress(id, good = it) }
@@ -596,19 +627,19 @@ object CatanCk {
     }
 
     private fun hexesNextTo(state: CatanState, seat: Int, terrain: Terrain): List<Int> =
-        (0 until CatanBoard.HEX_COUNT).filter { h ->
+        (0 until state.topo.HEX_COUNT).filter { h ->
             state.terrains[h] == terrain &&
-                CatanBoard.HEX_CORNERS[h].any { state.buildings[it]?.owner == seat }
+                state.topo.HEX_CORNERS[h].any { state.buildings[it]?.owner == seat }
         }
 
     /** Roads with a loose end: one end touching nothing else of anyone's. */
     private fun openRoads(state: CatanState): List<Int> =
-        (0 until CatanBoard.EDGE_COUNT).filter { e ->
+        (0 until state.topo.EDGE_COUNT).filter { e ->
             if (state.roads[e] == NO_PLAYER) return@filter false
-            val (a, b) = CatanBoard.EDGE_VERTICES[e]
+            val (a, b) = state.topo.EDGE_VERTICES[e]
             listOf(a, b).any { v ->
                 state.buildings[v] == null && knightAt(state, v) == null &&
-                    CatanBoard.VERTEX_EDGES[v].none { it != e && state.roads[it] != NO_PLAYER }
+                    state.topo.VERTEX_EDGES[v].none { it != e && state.roads[it] != NO_PLAYER }
             }
         }
 
@@ -1500,12 +1531,12 @@ object CatanCk {
 
     private fun production(state: CatanState, number: Int): CatanState {
         val gains = List(state.playerCount) { mutableMapOf<Good, Int>() }
-        for (h in 0 until CatanBoard.HEX_COUNT) {
+        for (h in 0 until state.topo.HEX_COUNT) {
             if (state.numbers[h] != number || h == state.robber) continue
             val terrain = state.terrains[h]
             val resource = terrain.produces ?: continue
             val commodity = commodityOf(terrain)
-            for (v in CatanBoard.HEX_CORNERS[h]) {
+            for (v in state.topo.HEX_CORNERS[h]) {
                 val building = state.buildings[v] ?: continue
                 val mine = gains[building.owner]
                 fun add(good: Good, n: Int) { mine[good] = (mine[good] ?: 0) + n }
@@ -1539,6 +1570,7 @@ object CatanCk {
         }
         val said = if (notes.isEmpty()) "nothing for anyone" else notes.joinToString(", ")
         s = s.copy(log = s.log + "The dice pay: $said.")
+        if (state.isSea) s = SeaRules.payCloth(s, number)
 
         // The aqueduct: a seat that was paid nothing may take a resource of its choice.
         val order = (0 until s.playerCount).map { (s.turn + it) % s.playerCount }
@@ -1546,7 +1578,11 @@ object CatanCk {
             improvement(s, seat, Track.SCIENCE) >= IMPROVEMENT_POWER_LEVEL && gains[seat].values.sum() == 0
         }
         val queued = enqueue(s, dry.map { AqueductChore(it) }, Back.AFTER_PRODUCTION)
-        return if (queued.ck!!.chores.isNotEmpty()) queued else queued.copy(phase = CatanPhase.PLAYING)
+        val next = if (queued.ck!!.chores.isNotEmpty()) queued else queued.copy(phase = CatanPhase.PLAYING)
+        // Gold is chosen before anything else; the chores (and then play) wait behind it.
+        val gold = if (state.isSea) CatanRules.goldOwed(state, number) else emptyList()
+        if (gold.isEmpty()) return next
+        return SeaRules.settleGold(next.copy(sea = next.sea!!.copy(gold = gold, afterGold = next.phase)))
     }
 
     // -----------------------------------------------------------------------

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

@@ -1,5 +1,9 @@
 package org.prolibertate.games.game.catan
 
+import org.prolibertate.games.game.engine.AiLevel
+import org.prolibertate.games.game.engine.AiProfile
+import org.prolibertate.games.game.engine.AiProfiles
+
 /**
  * The computer opponent for Cities & Knights, reached through [CatanAi].
  *
@@ -14,28 +18,44 @@ package org.prolibertate.games.game.catan
  * hired, and are activated when the barbarians draw near), never plays the
  * progress cards whose value depends on a plan (Inventor, Alchemist, Diplomat,
  * Deserter, Intrigue), and makes no domestic offers, though it answers them.
+ *
+ * The seat's profile shapes it as in [CatanAi]: easy plays on a whim and
+ * discards badly, hard sizes its knights to the barbarian threat, values cards
+ * by what its improvements still need and keeps its robber off its own hexes,
+ * and the style leans it toward knights and expansion, toward spending down
+ * a big hand, or toward the leader.
  */
-internal class CatanCkAi(private val ai: CatanAi) {
+internal class CatanCkAi(
+    private val ai: CatanAi,
+    private val profiles: AiProfiles = AiProfiles.DEFAULT,
+) {
 
-    fun choose(state: CatanState, seat: Int, legal: List<CatanMove>): CatanMove = when (state.phase) {
+    fun choose(state: CatanState, seat: Int, legal: List<CatanMove>): CatanMove {
+        val profile = profiles.of(seat)
+        return choose(state, seat, legal, profile)
+    }
+
+    private fun choose(state: CatanState, seat: Int, legal: List<CatanMove>, profile: AiProfile): CatanMove = when (state.phase) {
         CatanPhase.SETUP_FIRST, CatanPhase.SETUP_SECOND ->
-            ai.chooseSetup(state, seat, legal.filterIsInstance<SetupPlace>())
+            ai.chooseSetup(state, seat, legal.filterIsInstance<SetupPlace>(), profile)
 
         CatanPhase.AWAIT_ROLL -> legal.first { it is RollDice }
 
-        CatanPhase.CHORE -> chooseChore(state, seat, legal)
+        CatanPhase.CHORE -> chooseChore(state, seat, legal, profile)
 
-        CatanPhase.ROBBER -> chooseRobber(state, seat, legal.filterIsInstance<MoveRobber>())
+        CatanPhase.ROBBER -> chooseRobber(state, seat, legal.filterIsInstance<MoveRobber>(), profile)
 
-        CatanPhase.FREE_ROADS -> chooseFreeRoad(state, seat, legal)
+        CatanPhase.FREE_ROADS -> chooseFreeRoad(state, seat, legal, profile)
 
-        CatanPhase.TRADE_PENDING -> chooseResponse(state, seat, legal)
+        CatanPhase.TRADE_PENDING -> chooseResponse(state, seat, legal, profile)
 
         CatanPhase.TRADE_COUNTERS -> chooseCounter(state, legal)
 
-        CatanPhase.PLAYING -> choosePlaying(state, seat, legal)
+        CatanPhase.PLAYING -> choosePlaying(state, seat, legal, profile)
 
-        CatanPhase.DISCARDING, CatanPhase.GOLD, CatanPhase.GAME_OVER -> legal.firstOrNull()
+        CatanPhase.GOLD -> ai.chooseGold(state, seat, legal, profile)
+
+        CatanPhase.DISCARDING, CatanPhase.GAME_OVER -> legal.firstOrNull()
             ?: error("Nothing to choose in phase ${state.phase}")
     }
 
@@ -43,18 +63,25 @@ internal class CatanCkAi(private val ai: CatanAi) {
     // Chores
     // -----------------------------------------------------------------------
 
-    private fun chooseChore(state: CatanState, seat: Int, legal: List<CatanMove>): CatanMove {
+    private fun chooseChore(state: CatanState, seat: Int, legal: List<CatanMove>, profile: AiProfile): CatanMove {
         val ck = state.ck!!
         return when (val chore = ck.chores.first()) {
             is DiscardChore -> {
                 val n = minOf(chore.count, CatanCk.goodsCount(state, seat))
-                DiscardGoods(CatanCk.goodsList(state, seat).sortedBy { worth(state, seat, it) }.take(n))
+                val hand = CatanCk.goodsList(state, seat)
+                // Easy now and then throws away whatever comes to hand.
+                val order = if (profile.slips()) {
+                    hand.shuffled(profile.random)
+                } else {
+                    hand.sortedBy { worth(state, seat, it, profile) }
+                }
+                DiscardGoods(order.take(n))
             }
 
             is GiveChore -> {
                 val pool = CatanCk.goodsList(state, seat)
                     .filter { !chore.commoditiesOnly || it.isCommodity }
-                    .sortedBy { worth(state, seat, it) }
+                    .sortedBy { worth(state, seat, it, profile) }
                 GiveGoods(pool.take(minOf(chore.count, pool.size)))
             }
 
@@ -98,37 +125,62 @@ internal class CatanCkAi(private val ai: CatanAi) {
     // The robber
     // -----------------------------------------------------------------------
 
-    private fun chooseRobber(state: CatanState, seat: Int, moves: List<MoveRobber>): MoveRobber {
+    private fun chooseRobber(state: CatanState, seat: Int, moves: List<MoveRobber>, profile: AiProfile): MoveRobber {
         require(moves.isNotEmpty()) { "No legal robber move" }
         val points = CatanRules.publicVictoryPoints(state)
-        return moves.maxByOrNull { move ->
-            val hex = CatanBoard.hexIndex.getValue(move.hex)
+        val hard = profile.level == AiLevel.HARD
+        val spite = profile.style.spite
+        val leader = (0 until state.playerCount).filter { it != seat }.maxByOrNull { points[it] }
+        val victimWeight = 0.3 + 0.1 * profile.style.boldness
+        fun score(move: MoveRobber): Double {
+            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
                 val worth = if (building.type == BuildingType.CITY) 2 else 1
                 val odds = CatanBoard.numberOdds(state.numbers[hex]) / 36.0
-                score += if (building.owner == seat) -worth * odds else worth * odds
+                score += if (building.owner == seat) {
+                    -worth * odds * (if (hard) 1.5 else 1.0)
+                } else {
+                    worth * odds + if (building.owner == leader) spite * worth * odds else 0.0
+                }
             }
             if (move.victim != null) {
-                score += 0.15 * CatanCk.goodsCount(state, move.victim) + 0.3 * points[move.victim]
+                val cards = CatanCk.goodsCount(state, move.victim)
+                if (!hard || cards > 0) {
+                    score += 0.15 * cards + victimWeight * points[move.victim]
+                    if (move.victim == leader) score += 0.4 * spite
+                }
             }
-            score
-        } ?: moves.first()
+            return score
+        }
+        return if (profile.level == AiLevel.EASY) {
+            profile.pick(moves.sortedByDescending { score(it) })
+        } else {
+            moves.maxByOrNull { score(it) } ?: moves.first()
+        }
     }
 
     // -----------------------------------------------------------------------
     // The main phase
     // -----------------------------------------------------------------------
 
-    private fun choosePlaying(state: CatanState, seat: Int, legal: List<CatanMove>): CatanMove {
+    private fun choosePlaying(state: CatanState, seat: Int, legal: List<CatanMove>, profile: AiProfile): CatanMove {
         val ck = state.ck!!
-        val soon = ck.barbarians <= 3
+        val easy = profile.level == AiLevel.EASY
+        val hard = profile.level == AiLevel.HARD
+        val boldness = profile.style.boldness
+        // A cautious seat starts getting ready a step earlier.
+        val soon = ck.barbarians <= (if (boldness < 0) 4 else 3)
+        val endTurn = legal.lastOrNull { it is EndTurn }
+
+        // Easy loses the thread now and then and just passes.
+        if (easy && endTurn != null && profile.slips() && profile.random.nextBoolean()) return endTurn
 
         // Chase the robber off a hex it is squatting on.
         if (ck.attacked) {
             val onMine = legal.filterIsInstance<ChaseRobber>().firstOrNull()
-            val robberHurtsMe = CatanBoard.HEX_CORNERS[state.robber].any { state.buildings[it]?.owner == seat }
+            val robberHurtsMe = state.topo.HEX_CORNERS[state.robber].any { state.buildings[it]?.owner == seat }
             if (onMine != null && robberHurtsMe) return onMine
         }
 
@@ -138,10 +190,38 @@ internal class CatanCkAi(private val ai: CatanAi) {
             .maxByOrNull { production(state, it.vertex!!) }
             ?.let { return it }
 
-        legal.filterIsInstance<BuildCity>().maxByOrNull { production(state, it.vertex) }
-            ?.let { return it }
+        val cities = legal.filterIsInstance<BuildCity>()
+        val settlements = legal.filterIsInstance<BuildSettlement>()
+        if (hard) {
+            val city = cities.maxByOrNull { production(state, it.vertex) }
+            val settlement = settlements.maxByOrNull { ai.hardSpot(state, seat, it.vertex) }
+            val cityScore = if (city != null) production(state, city.vertex) + 0.15 else Double.NEGATIVE_INFINITY
+            val settleScore = if (settlement != null) {
+                ai.hardSpot(state, seat, settlement.vertex) + 0.3 + 0.1 * boldness
+            } else {
+                Double.NEGATIVE_INFINITY
+            }
+            if (city != null && cityScore >= settleScore) return city
+            if (settlement != null) return settlement
+        } else if (easy) {
+            if (cities.isNotEmpty()) return profile.pick(cities.sortedByDescending { production(state, it.vertex) })
+            if (settlements.isNotEmpty()) {
+                return profile.pick(settlements.sortedByDescending { ai.spotValue(state, it.vertex) })
+            }
+        } else {
+            cities.maxByOrNull { production(state, it.vertex) }?.let { return it }
 
-        legal.filterIsInstance<BuildSettlement>().maxByOrNull { ai.spotValue(state, it.vertex) }
+            settlements.maxByOrNull { ai.spotValue(state, it.vertex) }?.let { return it }
+        }
+
+        legal.filterIsInstance<RaidFortress>().firstOrNull()?.let { return it }
+        legal.filterIsInstance<DigCanal>().firstOrNull()?.let { return it }
+        legal.filterIsInstance<BuildWonder>().firstOrNull()?.let { return it }
+
+        // Seafarers: a ship toward land nobody has settled is worth more than a card.
+        legal.filterIsInstance<BuildShip>()
+            .filter { ai.shipValue(state, seat, it.edge) > 0.5 }
+            .maxByOrNull { ai.shipValue(state, seat, it.edge) }
             ?.let { return it }
 
         // Improvements spend cards nothing else needs. Favour the track furthest along.
@@ -150,16 +230,21 @@ internal class CatanCkAi(private val ai: CatanAi) {
             ?.let { return it }
 
         // Knights: stand ready by the time the barbarians land.
-        defence(state, seat, legal, soon)?.let { return it }
+        if (!(easy && profile.slips())) defence(state, seat, legal, soon, profile)?.let { return it }
 
-        progress(state, seat, legal)?.let { return it }
+        if (!(easy && profile.slips())) progress(state, seat, legal)?.let { return it }
 
         legal.filterIsInstance<BuildWall>().firstOrNull()?.let {
-            if (CatanCk.goodsCount(state, seat) >= 7) return it
+            if (CatanCk.goodsCount(state, seat) >= (if (boldness < 0) 5 else 7)) return it
         }
 
+        legal.filterIsInstance<BuildShip>()
+            .filter { ai.shipValue(state, seat, it.edge) > 0.15 }
+            .maxByOrNull { ai.shipValue(state, seat, it.edge) }
+            ?.let { return it }
+
         legal.filterIsInstance<BuildRoad>()
-            .filter { ai.roadValue(state, it) > 0.1 }
+            .filter { ai.roadValue(state, it) > 0.1 - 0.04 * boldness }
             .maxByOrNull { ai.roadValue(state, it) }
             ?.let { return it }
 
@@ -168,18 +253,43 @@ internal class CatanCkAi(private val ai: CatanAi) {
             .minByOrNull { CatanCk.bankRatio(state, seat, it.give) }
             ?.let { return it }
 
-        return legal.lastOrNull { it is EndTurn } ?: legal.first()
+        // Stay under the seven: a cautious (or careful) seat sells down a big hand.
+        if ((hard || boldness < 0) && CatanCk.goodsCount(state, seat) > 7) {
+            legal.filterIsInstance<GoodsBankTrade>()
+                .maxByOrNull { t ->
+                    held(state, seat, t.give) * 10.0 - CatanCk.bankRatio(state, seat, t.give) * 3.0 +
+                        worth(state, seat, t.get, profile)
+                }
+                ?.let { return it }
+        }
+
+        return endTurn ?: legal.first()
     }
 
     /** Hire, promote and activate so the knights are standing when the barbarians land. */
-    private fun defence(state: CatanState, seat: Int, legal: List<CatanMove>, soon: Boolean): CatanMove? {
+    private fun defence(
+        state: CatanState,
+        seat: Int,
+        legal: List<CatanMove>,
+        soon: Boolean,
+        profile: AiProfile,
+    ): CatanMove? {
         val mine = CatanCk.knightsOf(state, seat)
         val grainLeft = state.resources[seat][Resource.GRAIN] ?: 0
 
+        // Hard sizes the defence to the threat: the barbarians bring one strength
+        // per city on the board, and once the table's active knights outweigh them
+        // and this seat pulls its weight, the rest of its goods go elsewhere.
+        if (profile.level == AiLevel.HARD && soon && CatanCk.strength(state, seat) >= 1) {
+            val threat = state.buildings.count { it?.type == BuildingType.CITY }
+            val table = (0 until state.playerCount).sumOf { CatanCk.strength(state, it) }
+            if (table > threat) return null
+        }
+
         if (soon) {
             legal.filterIsInstance<ActivateKnight>().firstOrNull()?.let { return it }
         }
-        val want = if (soon) 4 else 2
+        val want = if (soon) 4 else if (profile.style.boldness > 0.5) 3 else 2
         if (mine.size < want) {
             legal.filterIsInstance<HireKnight>().maxByOrNull { ai.spotValue(state, it.vertex) }?.let { hire ->
                 // Keep a grain back for waking it, once the ship is close.
@@ -267,7 +377,7 @@ internal class CatanCkAi(private val ai: CatanAi) {
 
     /** What a building on [vertex] would draw, by the odds of its hexes and what the seat wants. */
     private fun production(state: CatanState, vertex: Int): Double =
-        CatanBoard.VERTEX_HEXES[vertex].sumOf { h ->
+        state.topo.VERTEX_HEXES[vertex].sumOf { h ->
             val want = state.terrains[h].produces?.let { ai.want(it) } ?: 0.0
             want * CatanBoard.numberOdds(state.numbers[h]) / 36.0
         }
@@ -289,26 +399,44 @@ internal class CatanCkAi(private val ai: CatanAi) {
         }
     }
 
-    private fun chooseFreeRoad(state: CatanState, seat: Int, legal: List<CatanMove>): CatanMove =
-        legal.filterIsInstance<BuildRoad>()
-            .filter { ai.roadValue(state, it) > 0.05 }
-            .maxByOrNull { ai.roadValue(state, it) }
+    private fun chooseFreeRoad(state: CatanState, seat: Int, legal: List<CatanMove>, profile: AiProfile): CatanMove {
+        val roads = legal.filterIsInstance<BuildRoad>().filter { ai.roadValue(state, it) > 0.05 }
+        val road = when {
+            roads.isEmpty() -> null
+            profile.level == AiLevel.EASY -> profile.pick(roads.sortedByDescending { ai.roadValue(state, it) })
+            else -> roads.maxByOrNull { ai.roadValue(state, it) }
+        }
+        return road
             ?: legal.firstOrNull { it is EndFreeRoads }
             ?: legal.first()
+    }
 
-    private fun chooseResponse(state: CatanState, seat: Int, legal: List<CatanMove>): CatanMove {
+    /** Extra the incoming cards must be worth: easy is not fussy, hard and spiteful seats are tougher on the leader. */
+    private fun tradeMargin(state: CatanState, seat: Int, other: Int, profile: AiProfile): Double {
+        var margin = 0.0
+        if (profile.level == AiLevel.EASY) margin -= 0.6
+        val points = CatanRules.publicVictoryPoints(state)
+        val leader = (0 until state.playerCount).filter { it != seat }.maxByOrNull { points[it] }
+        if (leader != null && other == leader) {
+            if (profile.level == AiLevel.HARD) margin += 0.4
+            margin += 0.5 * profile.style.spite
+        }
+        return margin
+    }
+
+    private fun chooseResponse(state: CatanState, seat: Int, legal: List<CatanMove>, profile: AiProfile): CatanMove {
         val decline = legal.first { it is DeclineTrade }
         val accept = legal.firstOrNull { it is AcceptTrade } ?: return decline
         val offer = state.ck?.goodsOffer
         if (offer != null) {
-            val incoming = offer.give.sumOf { worth(state, seat, it) }
-            val outgoing = offer.get.sumOf { worth(state, seat, it) }
-            return if (incoming > outgoing) accept else decline
+            val incoming = offer.give.sumOf { worth(state, seat, it, profile) }
+            val outgoing = offer.get.sumOf { worth(state, seat, it, profile) }
+            return if (incoming > outgoing + tradeMargin(state, seat, offer.by, profile)) accept else decline
         }
         val plain = state.pendingTrade ?: return decline
         val incoming = plain.give.sumOf { ai.want(it) }
         val outgoing = plain.get.sumOf { ai.want(it) }
-        return if (incoming > outgoing) accept else decline
+        return if (incoming > outgoing + tradeMargin(state, seat, plain.by, profile)) accept else decline
     }
 
     /** Counters to a human's... the AI never makes an offer, so this only guards the phase: take none. */
@@ -320,12 +448,22 @@ internal class CatanCkAi(private val ai: CatanAi) {
     // -----------------------------------------------------------------------
 
     /** What a card is worth to this seat: resources as the base AI sees them, commodities by what they buy. */
-    private fun worth(state: CatanState, seat: Int, good: Good): Double =
-        good.resource?.let { ai.want(it) } ?: when (good) {
+    private fun worth(state: CatanState, seat: Int, good: Good, profile: AiProfile = AiProfile.DEFAULT): Double {
+        val base = good.resource?.let { ai.want(it) } ?: when (good) {
             Good.PAPER -> 0.95
             Good.COIN -> 0.9
             else -> 0.85
         }
+        if (profile.level != AiLevel.HARD) return base
+        // Hard keeps the commodity an improvement is about to need.
+        var bonus = if (good.resource == Resource.ORE || good.resource == Resource.GRAIN) 0.1 else 0.0
+        for (track in Track.entries) {
+            if (Good.of(track.commodity) != good) continue
+            val level = CatanCk.improvement(state, seat, track)
+            if (level < IMPROVEMENT_MAX && held(state, seat, good) <= level + 1) bonus += 0.5
+        }
+        return base + bonus
+    }
 
     /** Which track to lean toward when two are level: politics for the knights, then science. */
     private fun trackLean(track: Track): Int = when (track) {

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

@@ -1,7 +1,16 @@
 package org.prolibertate.games.game.catan
 
+import kotlinx.serialization.KSerializer
 import kotlinx.serialization.SerialName
 import kotlinx.serialization.Serializable
+import kotlinx.serialization.descriptors.SerialDescriptor
+import kotlinx.serialization.encoding.Decoder
+import kotlinx.serialization.encoding.Encoder
+import kotlinx.serialization.json.JsonArray
+import kotlinx.serialization.json.JsonDecoder
+import kotlinx.serialization.json.JsonObject
+import kotlinx.serialization.json.JsonPrimitive
+import kotlinx.serialization.json.jsonObject
 
 /** Sentinel stored in [CatanState.roads] for an unclaimed road position. */
 const val NO_PLAYER = -1
@@ -45,6 +54,36 @@ enum class Terrain(val produces: Resource?) {
 
     /** Seafarers: a gold field. A settlement beside it takes any resource its owner likes when its number rolls. */
     GOLD(null),
+
+    /**
+     * Seafarers: land not yet found. It becomes a resource or gold when a road or ship first reaches it
+     * (`SeaState.fogDeck`). Until then nothing is built on it, nothing produces, and the robber keeps off.
+     */
+    FOG(null),
+
+    /** Seafarers, Cloth for Catan: a village. It pays cloth, not cards, to the settlements around it when its number rolls. */
+    VILLAGE(null),
+
+    /**
+     * Seafarers, Pirate Islands: a pirate fortress. It stands until ships raid it (`SeaState.fortress`), and
+     * nobody settles its island meanwhile. Once taken it becomes desert.
+     */
+    FORTRESS(null),
+}
+
+/** Base-island scenarios: the board and goals of a game without Seafarers. Seafarers games choose a [SeaScenario] instead. */
+@Serializable
+enum class BaseScenario(val title: String, val blurb: String) {
+    RANDOM_MAP("Random map", "The usual island, its tiles and numbers shuffled for every game."),
+    FIRST_ISLAND(
+        "First Island",
+        "The same fixed island every game, so the set-up is not a surprise: good for a first game or a rematch.",
+    ),
+    HARBORMASTER(
+        "The Harbormaster",
+        "Harbours matter. A settlement on a harbour counts a point and a city two; the first to three has the " +
+            "Harbormaster title, worth 2 victory points, and whoever gets more takes it.",
+    ),
 }
 
 /** Axial coordinate of one hex on the board. See [CatanBoard]. */
@@ -151,12 +190,9 @@ enum class CatanPhase {
     CHORE,
 }
 
-/** Which rules a table plays. The expansion is a whole rule set, not a toggle. */
+/** An expansion a table can switch on. The base game is what is left with none selected. */
 @Serializable
-enum class CatanRuleSet {
-    /** The base game: development cards, Largest Army, a robber from the start. */
-    BASE,
-
+enum class CatanExpansion {
     /** Cities & Knights: commodities, knights, barbarians, city improvements. */
     CITIES_AND_KNIGHTS,
 
@@ -164,16 +200,59 @@ enum class CatanRuleSet {
     SEAFARERS,
 }
 
-@Serializable
+/**
+ * What a table plays: the expansions switched on, and the Seafarers map when that one is.
+ *
+ * Saves written before expansions became toggles carry `"ruleSet"` instead of `"expansions"`;
+ * [CatanOptionsSerializer] reads either.
+ */
+@Serializable(with = CatanOptionsSerializer::class)
 data class CatanOptions(
     val playerCount: Int = 3,
     val pointsToWin: Int = 10,
-    val ruleSet: CatanRuleSet = CatanRuleSet.BASE,
+    val expansions: Set<CatanExpansion> = emptySet(),
+    val scenario: SeaScenario = SeaScenario.NEW_SHORES,
+    val baseScenario: BaseScenario = BaseScenario.RANDOM_MAP,
 ) {
     init {
         require(playerCount in 3..4) { "The island seats three or four players" }
         require(pointsToWin >= 2) { "pointsToWin must be at least 2" }
     }
+
+    val seafarers: Boolean get() = CatanExpansion.SEAFARERS in expansions
+    val citiesAndKnights: Boolean get() = CatanExpansion.CITIES_AND_KNIGHTS in expansions
+}
+
+/** The wire shape of [CatanOptions]. */
+@Serializable
+private class CatanOptionsWire(
+    val playerCount: Int = 3,
+    val pointsToWin: Int = 10,
+    val expansions: Set<CatanExpansion> = emptySet(),
+    val scenario: SeaScenario = SeaScenario.NEW_SHORES,
+    val baseScenario: BaseScenario = BaseScenario.RANDOM_MAP,
+)
+
+/** Reads the legacy single `ruleSet` field as an expansion set. */
+object CatanOptionsSerializer : KSerializer<CatanOptions> {
+    override val descriptor: SerialDescriptor = CatanOptionsWire.serializer().descriptor
+
+    override fun serialize(encoder: Encoder, value: CatanOptions) = encoder.encodeSerializableValue(
+        CatanOptionsWire.serializer(),
+        CatanOptionsWire(value.playerCount, value.pointsToWin, value.expansions, value.scenario, value.baseScenario),
+    )
+
+    override fun deserialize(decoder: Decoder): CatanOptions {
+        val input = decoder as JsonDecoder
+        var obj = input.decodeJsonElement().jsonObject
+        val legacy = (obj["ruleSet"] as? JsonPrimitive)?.content
+        if (legacy != null) {
+            val expansions = if (legacy == "BASE") emptyList() else listOf(JsonPrimitive(legacy))
+            obj = JsonObject(obj - "ruleSet" + ("expansions" to JsonArray(expansions)))
+        }
+        val wire = input.json.decodeFromJsonElement(CatanOptionsWire.serializer(), obj)
+        return CatanOptions(wire.playerCount, wire.pointsToWin, wire.expansions, wire.scenario, wire.baseScenario)
+    }
 }
 
 /**
@@ -198,6 +277,8 @@ data class CatanState(
     val turn: Int,
     /** How many setup placements are done, 0 until 2 * playerCount. */
     val setupIndex: Int,
+    /** The seat that places first and takes the first turn; drawn from the table seed. */
+    val firstSeat: Int = 0,
     /** Monotonic turn counter, 0 during setup, 1 from the first real turn. */
     val turnNumber: Int,
     /** Terrain per hex, indexed like [CatanBoard.HEXES]. */
@@ -242,6 +323,8 @@ data class CatanState(
     val log: List<String>,
     /** Everything Cities & Knights adds; null in the base game. */
     val ck: CkState? = null,
+    /** The Harbormaster scenario: the seat holding the title, or null. */
+    val harbormaster: Int? = null,
     /** Everything Seafarers adds (ships, the pirate, islands); null in the other rule sets. */
     val sea: SeaState? = null,
 ) {
@@ -414,12 +497,85 @@ data class SeaState(
     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. */
+    /** The island that counts as home: the largest, and the pirate-free start of the original map. */
     val home: Int,
+    /** The islands the starting settlements may go on. Empty in a save from before there were several: just [home]. */
+    val starts: List<Int> = emptyList(),
     /** Gold owed after a roll, front first: each seat chooses [GoldOwed.count] cards. */
     val gold: List<GoldOwed> = emptyList(),
+    /**
+     * The tiles still face down, next to be found first. Hidden from every view but the host's, like the
+     * development deck.
+     */
+    val fogDeck: List<FogTile> = emptyList(),
+    /** Where the game goes when the gold queue empties: [CatanPhase.PLAYING] unless a find interrupted something else. */
+    val afterGold: CatanPhase? = null,
+    /** Cloth tokens each seat holds (Cloth for Catan); empty when the scenario has none. Two make a victory point. */
+    val cloth: List<Int> = emptyList(),
+    /** Cloth still on each hex's village, by hex (Cloth for Catan); empty when the scenario has none. */
+    val villageCloth: List<Int> = emptyList(),
+    /** The tribe chip waiting on each hex (Forgotten Tribe), by hex; empty when the scenario has none. */
+    val chips: List<TribeChip> = emptyList(),
+    /** Seats that took a harbour chip and so trade 3:1 anywhere. */
+    val harbourSeats: List<Int> = emptyList(),
+    /** Victory points each seat holds from tribe chips; empty until one is taken. */
+    val chipPoints: List<Int> = emptyList(),
+    /** Strength still left in each hex's pirate fortress, by hex (Pirate Islands); empty when the map has none. */
+    val fortress: List<Int> = emptyList(),
+    /** Victory points each seat holds for taking fortresses; empty until one falls. */
+    val raidPoints: List<Int> = emptyList(),
+    /** Wonder stages each seat has built (Wonders of Catan), by seat; empty when the scenario has none. */
+    val wonders: List<Int> = emptyList(),
+    /** The chest under each hex of fog, by hex (Treasure Islands, Oases); found when the hex is. Hidden from other views. */
+    val treasures: List<Treasure> = emptyList(),
+    /** Units dug so far into each canal tile, by hex (Great Canal); empty when the map has none. */
+    val canalUnits: List<Int> = emptyList(),
+    /** The number token waiting under each canal tile, by hex; it shows when the tile is finished. */
+    val canalNumbers: List<Int> = emptyList(),
+    /** Canal units each seat has dug; every two are a victory point. */
+    val canalDug: List<Int> = emptyList(),
 )
 
+/** What a treasure chest holds (Treasure Islands). */
+@Serializable
+enum class Treasure {
+    NONE,
+
+    /** One brick, one wool and one grain. */
+    BRICK_WOOL_GRAIN,
+
+    /** One resource of the finder's choice. */
+    CHOICE,
+
+    /** A development card (a resource of choice in Cities & Knights, which has none). */
+    DEV_CARD,
+
+    /** Two roads' worth of cards: two lumber and two brick. */
+    ROADS,
+}
+
+/** What the first settler beside a tribe hex takes (Forgotten Tribe). */
+@Serializable
+enum class TribeChip {
+    NONE,
+
+    /** One victory point. */
+    POINT,
+
+    /** A 3:1 harbour, good wherever the seat trades. */
+    HARBOUR,
+
+    /** Two resources of the seat's choice. */
+    GOLD,
+}
+
+/** One tile of the fog: what the hex turns out to be and the number token that comes with it. */
+@Serializable
+data class FogTile(val terrain: Terrain, val number: Int)
+
+/** Whether [island] is one the game starts on, and so never earns the new-island bonus. */
+fun SeaState.isStart(island: Int): Boolean = island == home || island in starts
+
 @Serializable
 data class GoldOwed(val seat: Int, val count: Int)
 
@@ -442,3 +598,18 @@ data class MovePirate(val hex: HexCoord, val victim: Int? = null) : CatanMove
 @Serializable
 @SerialName("gold")
 data class PickGold(val cards: List<Resource>) : CatanMove
+
+/** Raid the pirate fortress on [hex] from a ship beside it: 1 ore, 1 wool and 1 grain take one point of its strength. */
+@Serializable
+@SerialName("raid")
+data class RaidFortress(val hex: HexCoord) : CatanMove
+
+/** Build the next stage of your wonder, which needs a city of yours; the stage's cost is in `SeaRules.WONDER_STAGES`. */
+@Serializable
+@SerialName("wonder")
+data object BuildWonder : CatanMove
+
+/** Dig one unit of the canal tile on [hex]: 1 brick and 1 ore, from a seat with a settlement or city beside it. */
+@Serializable
+@SerialName("dig")
+data class DigCanal(val hex: HexCoord) : CatanMove

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

@@ -54,15 +54,17 @@ object CatanRules : GameRules<CatanState, CatanMove> {
             "Seat count ${config.seats.size} does not match ${options.playerCount} players"
         }
 
-        val sea = options.ruleSet == CatanRuleSet.SEAFARERS
-        val scenario = SeaScenario.NEW_SHORES
+        val sea = options.seafarers
+        val scenario = options.scenario
         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)
+            ?: CatanBoard.generate(
+                if (options.baseScenario == BaseScenario.FIRST_ISLAND) CatanBoard.FIRST_ISLAND_SEED else 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
+        val ck = options.citiesAndKnights
         // Cities & Knights has no development cards: knights and progress
         // cards take their place.
         val devDeck = if (ck) {
@@ -73,12 +75,17 @@ object CatanRules : GameRules<CatanState, CatanMove> {
                 .shuffled(Random(config.seed + 1))
         }
 
+        // Seat 0 used to lead every game; a separate stream from the board and
+        // the deck keeps the same seed giving the same table.
+        val firstSeat = Random(config.seed + 2).nextInt(options.playerCount)
+
         return CatanState(
             options = options,
             seed = config.seed,
             phase = CatanPhase.SETUP_FIRST,
-            turn = 0,
+            turn = firstSeat,
             setupIndex = 0,
+            firstSeat = firstSeat,
             turnNumber = 0,
             terrains = board.terrains,
             numbers = board.numbers,
@@ -114,6 +121,17 @@ object CatanRules : GameRules<CatanState, CatanMove> {
                     pirate = it.pirate,
                     islandBonus = List(topo.islandCount) { NO_PLAYER },
                     home = it.home,
+                    starts = it.starts,
+                    fogDeck = it.fogDeck,
+                    cloth = if (it.villageCloth.isEmpty()) emptyList() else List(options.playerCount) { 0 },
+                    villageCloth = it.villageCloth,
+                    chips = it.chips,
+                    fortress = it.fortress,
+                    treasures = it.treasures,
+                    canalUnits = if (it.canalNumbers.isEmpty()) emptyList() else List(topo.HEX_COUNT) { 0 },
+                    canalNumbers = it.canalNumbers,
+                    canalDug = if (it.canalNumbers.isEmpty()) emptyList() else List(options.playerCount) { 0 },
+                    wonders = if (scenario == SeaScenario.WONDERS_OF_CATAN) List(options.playerCount) { 0 } else emptyList(),
                 )
             },
         )
@@ -121,8 +139,9 @@ object CatanRules : GameRules<CatanState, CatanMove> {
 
     override fun currentSeat(state: CatanState): Int? = when (state.phase) {
         CatanPhase.GAME_OVER -> null
-        CatanPhase.SETUP_FIRST -> state.setupIndex
-        CatanPhase.SETUP_SECOND -> 2 * state.playerCount - 1 - state.setupIndex
+        CatanPhase.SETUP_FIRST -> (state.firstSeat + state.setupIndex) % state.playerCount
+        CatanPhase.SETUP_SECOND ->
+            (state.firstSeat + 2 * state.playerCount - 1 - state.setupIndex) % state.playerCount
         CatanPhase.DISCARDING -> state.discardSeat
         CatanPhase.TRADE_PENDING -> state.pendingTrade?.asking?.takeIf { it >= 0 }
             ?: state.ck?.goodsOffer?.asking?.takeIf { it >= 0 }
@@ -201,8 +220,10 @@ object CatanRules : GameRules<CatanState, CatanMove> {
         val moves = mutableListOf<SetupPlace>()
         for (v in 0 until state.topo.VERTEX_COUNT) {
             if (!vertexOpenForSettlement(state, v)) continue
-            // Seafarers: everyone starts on the home island.
-            if (state.sea != null && state.topo.vertexIsland[v] != state.sea.home) continue
+            // Seafarers: the starting settlements go on a starting island.
+            if (state.sea != null && !state.sea.isStart(state.topo.vertexIsland[v])) continue
+            // Nobody starts beside land that has not been found.
+            if (state.topo.VERTEX_HEXES[v].any { state.terrains[it] == Terrain.FOG }) continue
             for (e in state.topo.VERTEX_EDGES[v]) {
                 if (state.roads[e] != NO_PLAYER || !state.topo.edgeLand[e]) continue
                 moves += SetupPlace(v, e)
@@ -238,7 +259,7 @@ object CatanRules : GameRules<CatanState, CatanMove> {
     private fun robberMoves(state: CatanState, seat: Int): List<MoveRobber> {
         val moves = mutableListOf<MoveRobber>()
         for (h in 0 until state.topo.HEX_COUNT) {
-            if (h == state.robber || !state.topo.land[h]) continue
+            if (h == state.robber || !state.topo.land[h] || state.terrains[h] == Terrain.FOG || state.terrains[h] == Terrain.FORTRESS) continue
             val victims = state.topo.HEX_CORNERS[h]
                 .mapNotNull { state.buildings[it] }
                 .map { it.owner }
@@ -270,6 +291,7 @@ object CatanRules : GameRules<CatanState, CatanMove> {
         if (state.isSea) {
             if (affordable(state, seat, SeaRules.SHIP_COST)) moves += SeaRules.buildShipMoves(state, seat)
             moves += SeaRules.moveShipMoves(state, seat)
+            moves += SeaRules.scenarioMoves(state, seat)
         }
 
         if (!state.devCardPlayedThisTurn) {
@@ -404,6 +426,7 @@ 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) && state.topo.vertexLand[v] &&
+            !SeaRules.fortressHolds(state, v) &&
             state.topo.VERTEX_NEIGHBORS[v].all { state.buildings[it] == null }
 
     /**
@@ -457,6 +480,9 @@ object CatanRules : GameRules<CatanState, CatanMove> {
             is MoveShip -> applyMoveShip(state, seat, move)
             is MovePirate -> applyMovePirate(state, seat, move)
             is PickGold -> applyPickGold(state, seat, move)
+            is RaidFortress -> SeaRules.applyRaid(state, seat, move)
+            is DigCanal -> SeaRules.applyDig(state, seat, move)
+            BuildWonder -> SeaRules.applyWonder(state, seat)
             is BuildRoad -> applyBuildRoad(state, seat, move)
             is BuildSettlement -> applyBuildSettlement(state, seat, move)
             is BuildCity -> applyBuildCity(state, seat, move)
@@ -508,13 +534,13 @@ object CatanRules : GameRules<CatanState, CatanMove> {
         }
 
         val newIndex = state.setupIndex + 1
-        s = s.copy(setupIndex = newIndex)
+        s = refreshHarbormaster(s.copy(setupIndex = newIndex))
         return when {
             newIndex >= 2 * n -> s.copy(
                 phase = CatanPhase.AWAIT_ROLL,
-                turn = 0,
+                turn = state.firstSeat,
                 turnNumber = 1,
-                log = s.log + "Setup done — seat 0 leads.",
+                log = s.log + "Setup done — seat ${state.firstSeat} leads.",
             )
 
             newIndex == n -> s.copy(phase = CatanPhase.SETUP_SECOND)
@@ -586,12 +612,13 @@ object CatanRules : GameRules<CatanState, CatanMove> {
         s = s.copy(
             log = s.log + "Seat ${state.turn} rolls ${state.lastDice.joinToString(" + ")} — $said.",
         )
+        if (state.isSea) s = SeaRules.payCloth(s, number)
         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> {
+    internal 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) {
@@ -654,7 +681,9 @@ object CatanRules : GameRules<CatanState, CatanMove> {
             s = s.copy(pendingFreeRoads = left)
             if (left == 0) s = s.copy(phase = phaseAfterRoads(s))
         }
-        return checkWin(s.copy(log = s.log + "Seat $seat builds a road on ${move.edge}."))
+        s = s.copy(log = s.log + "Seat $seat builds a road on ${move.edge}.")
+        if (state.sea != null) s = SeaRules.reveal(s, seat, move.edge)
+        return checkWin(s)
     }
 
     private fun applyBuildShip(state: CatanState, seat: Int, move: BuildShip): CatanState {
@@ -673,7 +702,7 @@ object CatanRules : GameRules<CatanState, CatanMove> {
             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}."))
+        return checkWin(SeaRules.reveal(s.copy(log = s.log + "Seat $seat launches a ship on ${move.edge}."), seat, move.edge))
     }
 
     private fun applyMoveShip(state: CatanState, seat: Int, move: MoveShip): CatanState {
@@ -686,12 +715,17 @@ object CatanRules : GameRules<CatanState, CatanMove> {
         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}.")
-        })
+        return checkWin(
+            SeaRules.reveal(
+                refreshLongestRoad(s).let { it.copy(log = it.log + "Seat $seat sails a ship from ${move.from} to ${move.to}.") },
+                seat,
+                move.to,
+            ),
+        )
     }
 
     private fun applyMovePirate(state: CatanState, seat: Int, move: MovePirate): CatanState {
+        if (state.isCk) return CatanCk.applyPirate(state, seat, move)
         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 = ""
@@ -726,7 +760,7 @@ object CatanRules : GameRules<CatanState, CatanMove> {
             },
         )
         s = payCost(s, seat, SETTLEMENT_COST)
-        s = SeaRules.claimIsland(s, seat, move.vertex)
+        s = SeaRules.settled(s, seat, move.vertex)
         // A settlement can break another player's road, so the award is
         // recomputed for everyone.
         s = refreshLongestRoad(s)
@@ -991,16 +1025,64 @@ object CatanRules : GameRules<CatanState, CatanMove> {
         }
         state.longestRoadOwner?.let { points[it] += 5 }
         state.largestArmyOwner?.let { points[it] += 5 }
+        state.harbormaster?.let { points[it] += HARBORMASTER_POINTS }
         if (state.isSea) for (seat in points.indices) points[seat] += SeaRules.bonusPoints(state, seat)
         return points.toList()
     }
 
+    // -----------------------------------------------------------------------
+    // The Harbormaster
+    // -----------------------------------------------------------------------
+
+    /** The scenario's title: points for a harbour town and for the Harbormaster. */
+    const val HARBORMASTER_MINIMUM = 3
+    const val HARBORMASTER_POINTS = 2
+
+    /** Whether this table plays the Harbormaster (never in a Seafarers game, which has its own maps). */
+    internal fun harbormasterGame(state: CatanState): Boolean =
+        state.options.baseScenario == BaseScenario.HARBORMASTER && !state.isSea
+
+    /** Harbour points: a settlement on a harbour counts 1, a city 2, for each harbour it touches. */
+    fun harbourPoints(state: CatanState, seat: Int): Int {
+        var total = 0
+        for (port in state.ports) {
+            val (a, b) = state.topo.EDGE_VERTICES[port.edge]
+            val own = listOfNotNull(state.buildings[a], state.buildings[b]).firstOrNull { it.owner == seat }
+            if (own != null) total += if (own.type == BuildingType.CITY) 2 else 1
+        }
+        return total
+    }
+
+    /** Gives the title to the first seat with three harbour points, and to a seat with strictly more than the holder. */
+    internal fun refreshHarbormaster(state: CatanState): CatanState {
+        if (!harbormasterGame(state)) return state
+        val points = List(state.playerCount) { harbourPoints(state, it) }
+        val holder = state.harbormaster
+        val best = points.max()
+        val leaders = points.indices.filter { points[it] == best }
+        val next = when {
+            holder == null -> leaders.singleOrNull()?.takeIf { best >= HARBORMASTER_MINIMUM }
+            best > points[holder] -> leaders.singleOrNull() ?: holder
+            else -> holder
+        }
+        if (next == holder) return state
+        return state.copy(
+            harbormaster = next,
+            log = state.log + if (holder == null) {
+                "Seat $next is now harbormaster."
+            } else {
+                "Seat $next has taken the title harbormaster from seat $holder."
+            },
+        )
+    }
+
     fun victoryPoints(state: CatanState, seat: Int): Int =
         publicVictoryPoints(state)[seat] +
             state.devHands[seat].count { it.type == DevCardType.VICTORY_POINT }
 
-    internal fun checkWin(state: CatanState): CatanState {
-        if (state.phase == CatanPhase.GAME_OVER) return state
+    internal fun checkWin(settled: CatanState): CatanState {
+        if (settled.phase == CatanPhase.GAME_OVER) return settled
+        val state = refreshHarbormaster(settled)
         val seat = state.turn
         val points = victoryPoints(state, seat)
         if (points < state.options.pointsToWin) return state
@@ -1129,7 +1211,7 @@ object CatanRules : GameRules<CatanState, CatanMove> {
         cards.groupingBy { it }.eachCount()
 
     /** Hands with [delta] of each resource added to (or, with negative sign, removed from) [seat]'s. */
-    private fun withCounts(
+    internal fun withCounts(
         resources: List<Map<Resource, Int>>,
         seat: Int,
         delta: Map<Resource, Int>,
@@ -1167,6 +1249,7 @@ object CatanRules : GameRules<CatanState, CatanMove> {
             val mine = state.buildings[a]?.owner == seat || state.buildings[b]?.owner == seat
             if (mine) best = port.ratio
         }
+        if (best > 3 && state.sea?.harbourSeats?.contains(seat) == true) best = 3
         return best
     }
 
@@ -1177,7 +1260,7 @@ object CatanRules : GameRules<CatanState, CatanMove> {
             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
+        return if (state.sea?.harbourSeats?.contains(seat) == true) 3 else 4
     }
 
     // -----------------------------------------------------------------------
@@ -1198,6 +1281,7 @@ object CatanRules : GameRules<CatanState, CatanMove> {
         state.copy(
             // Hidden information stays with the holder and the host.
             devDeck = emptyList(),
+            sea = state.sea?.copy(fogDeck = emptyList(), treasures = emptyList()),
             devHands = state.devHands.mapIndexed { index, hand ->
                 if (index == seat) hand else emptyList()
             },

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

@@ -5,11 +5,69 @@ 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) {
+enum class SeaScenario(val title: String, val blurb: String, val start: SeaStart = SeaStart.HOME_ONLY) {
     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.",
     ),
+    FOUR_ISLANDS(
+        "Four Islands",
+        "Four equal islands, one start each, and two gold islets in the middle. Settle your own island, then sail.",
+        SeaStart.MAIN_ISLANDS,
+    ),
+    THROUGH_THE_DESERT(
+        "Through the Desert",
+        "One island cut by a broad desert that yields nothing. Reach the far side by road, or sail round to the islets.",
+    ),
+    FOG_ISLANDS(
+        "The Fog Islands",
+        "A home island, an islet, and a bank of fog. Land in the fog is face down until a road or ship reaches it; " +
+            "the finder takes a card of what lies there.",
+    ),
+    TREASURE_ISLANDS(
+        "The Treasure Islands",
+        "Chests lie hidden on the fog-covered isles beside a home island. Whoever uncovers one opens it: " +
+            "cards, a resource of choice, a development card or a road's worth of materials.",
+    ),
+    OASES(
+        "The Oases",
+        "An enormous desert, with fertile oases hidden inside it. Roads that reach an oasis uncover it " +
+            "and whatever treasure is buried there.",
+    ),
+    GREAT_CANAL(
+        "The Great Canal",
+        "A desert strip splits the island. Dig the canal tile by tile (a brick and an ore a unit) and each finished " +
+            "tile becomes grain land; every two units dug are a victory point.",
+    ),
+    PIRATE_ISLANDS(
+        "Pirate Islands",
+        "Two isles are held by pirate fortresses. Sail ships beside one and raid it with ore, wool and grain; " +
+            "nobody may settle the isle until the fortress falls, and the one who takes it earns two points.",
+    ),
+    WONDERS_OF_CATAN(
+        "Wonders of Catan",
+        "Two big islands and room to grow. Raise a city, then build a wonder in four stages; each stage is a " +
+            "victory point and the first to finish all four wins.",
+    ),
+    CLOTH_FOR_CATAN(
+        "Cloth for Catan",
+        "Four villages weave cloth. Settle beside one and it pays you a cloth token whenever its number rolls; " +
+            "every two tokens are a victory point.",
+    ),
+    FORGOTTEN_TRIBE(
+        "The Forgotten Tribe",
+        "Four small isles hold the chips of a lost tribe. The first to settle beside one takes it: " +
+            "a victory point, a harbour, or gold.",
+    ),
+}
+
+/** Where the starting settlements may go. */
+enum class SeaStart {
+    /** The largest island only. */
+    HOME_ONLY,
+
+    /** Any island big enough to live on (four hexes or more); the small ones are prizes to sail to. */
+    MAIN_ISLANDS,
 }
 
 /**
@@ -33,8 +91,134 @@ object SeaBoards {
         "..........",
     )
 
+    private val FOUR_ISLANDS_MAP = listOf(
+        "............",
+        "..###..###..",
+        "..###..###..",
+        "............",
+        "..$.....$...",
+        "............",
+        "..###..###..",
+        "..###..###..",
+        "............",
+    )
+
+    private val THROUGH_THE_DESERT_MAP = listOf(
+        "............",
+        ".###DD###...",
+        ".###DDD###..",
+        "..###DD###..",
+        "............",
+        "..$.....$...",
+        "............",
+        "...##...#...",
+        "............",
+    )
+
+    /** `F` is fog: land that is face down until found. */
+    private val FOG_ISLANDS_MAP = listOf(
+        "............",
+        ".###....FF..",
+        ".####..FFF..",
+        "..#D#..FFFF.",
+        ".###...FFF..",
+        ".......FF...",
+        "...##.......",
+        "............",
+    )
+
+    /** `V` is a village; `t` is a resource hex that carries a tribe chip. */
+    private val CLOTH_FOR_CATAN_MAP = listOf(
+        "............",
+        "..V###..V##.",
+        "..#####..##.",
+        "..####V..#..",
+        "...###......",
+        ".......##V..",
+        "............",
+        "...##.......",
+        "............",
+    )
+
+    private val FORGOTTEN_TRIBE_MAP = listOf(
+        "............",
+        "..###..t#...",
+        "..#####..#t.",
+        "..#####..#..",
+        "..####......",
+        "........t##.",
+        ".#t.........",
+        "............",
+    )
+
+    private val TREASURE_ISLANDS_MAP = listOf(
+        "............",
+        "..###..FF...",
+        "..####..FF..",
+        "..#####.....",
+        "..###...F...",
+        ".......FF...",
+        "..F.........",
+        "............",
+    )
+
+    private val OASES_MAP = listOf(
+        "............",
+        "..###DD###..",
+        "..#DDFDD#...",
+        "..#DDDFD#...",
+        "..#DFDDD#...",
+        "..###DD###..",
+        "............",
+    )
+
+    /** `C` is a canal tile: desert with a number hidden under it until it is dug out. */
+    private val GREAT_CANAL_MAP = listOf(
+        "............",
+        "..#####.....",
+        "..#####.....",
+        "..CCCCC.....",
+        "..#####.....",
+        "..#####.....",
+        "........$$..",
+        "............",
+    )
+
+    /** `P` is a pirate fortress. */
+    private val PIRATE_ISLANDS_MAP = listOf(
+        "............",
+        "..####.P##..",
+        "..####..##..",
+        "..####......",
+        "..####..P#..",
+        "...##...##..",
+        "............",
+        "............",
+    )
+
+    private val WONDERS_OF_CATAN_MAP = listOf(
+        "............",
+        "..####.###..",
+        ".#####.####.",
+        "..###D.###..",
+        ".......##...",
+        "..$......$..",
+        "...##.......",
+        "............",
+    )
+
     private fun rows(scenario: SeaScenario): List<String> = when (scenario) {
         SeaScenario.NEW_SHORES -> NEW_SHORES_MAP
+        SeaScenario.FOUR_ISLANDS -> FOUR_ISLANDS_MAP
+        SeaScenario.THROUGH_THE_DESERT -> THROUGH_THE_DESERT_MAP
+        SeaScenario.FOG_ISLANDS -> FOG_ISLANDS_MAP
+        SeaScenario.TREASURE_ISLANDS -> TREASURE_ISLANDS_MAP
+        SeaScenario.OASES -> OASES_MAP
+        SeaScenario.GREAT_CANAL -> GREAT_CANAL_MAP
+        SeaScenario.PIRATE_ISLANDS -> PIRATE_ISLANDS_MAP
+        SeaScenario.WONDERS_OF_CATAN -> WONDERS_OF_CATAN_MAP
+        SeaScenario.CLOTH_FOR_CATAN -> CLOTH_FOR_CATAN_MAP
+        SeaScenario.FORGOTTEN_TRIBE -> FORGOTTEN_TRIBE_MAP
     }
 
     private val topologies = HashMap<SeaScenario, Topology>()
@@ -72,8 +256,34 @@ object SeaBoards {
         val pirate: Int,
         val ports: List<Port>,
         val home: Int,
+        /** The islands the starting settlements may go on; always includes [home]. */
+        val starts: List<Int> = listOf(home),
+        /** The tiles under the fog, in the order they will be found. */
+        val fogDeck: List<FogTile> = emptyList(),
+        /** The tribe chip on each hex, or [TribeChip.NONE]; empty when the map has none. */
+        val chips: List<TribeChip> = emptyList(),
+        /** Cloth waiting on each village, by hex; empty when the map has none. */
+        val villageCloth: List<Int> = emptyList(),
+        /** Strength of the fortress on each hex, by hex; empty when the map has none. */
+        val fortress: List<Int> = emptyList(),
+        /** The chest under each hex, by hex; empty when the map has none. */
+        val treasures: List<Treasure> = emptyList(),
+        /** The number under each canal tile, by hex; empty when the map has none. */
+        val canalNumbers: List<Int> = emptyList(),
     )
 
+    /** An island of this many land hexes or more can be started on. */
+    private const val MAIN_ISLAND_HEXES = 4
+
+    /** Cloth each village starts with. */
+    const val VILLAGE_CLOTH = 6
+
+    /** Ships' raids a pirate fortress takes to fall. */
+    const val FORTRESS_STRENGTH = 3
+
+    /** Chests dealt to the fog, at most. */
+    private const val CHESTS = 5
+
     private val RESOURCE_TILES = listOf(
         Terrain.FOREST, Terrain.PASTURE, Terrain.FIELDS, Terrain.HILLS, Terrain.MOUNTAINS,
     )
@@ -88,19 +298,24 @@ object SeaBoards {
         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 plain = kinds.indices.filter { kinds[it] == '#' || kinds[it] == 't' }
         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)]
+                '#', 't' -> pool[plain.indexOf(h)]
+                'V' -> Terrain.VILLAGE
+                'P' -> Terrain.FORTRESS
+                'C' -> Terrain.DESERT
+                'F' -> Terrain.FOG
                 else -> Terrain.SEA
             }
         }
 
-        val numbered = terrains.indices.filter { terrains[it] != Terrain.SEA && terrains[it] != Terrain.DESERT }
+        // The fog hexes take part as slots, so the tokens they hide are dealt from the same pile.
+        val numbered = terrains.indices.filter { terrains[it] != Terrain.SEA && (terrains[it] != Terrain.DESERT && terrains[it] != Terrain.FORTRESS || kinds[it] == 'C') }
         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)
@@ -119,6 +334,14 @@ object SeaBoards {
             attempt++
         }
 
+        // What lies under the fog: mostly resources, one gold field in five, drawn from the same tokens.
+        val fogHexes = terrains.indices.filter { terrains[it] == Terrain.FOG }
+        val fogKinds = List(fogHexes.size) { i ->
+            if (i % 5 == 4) Terrain.GOLD else RESOURCE_TILES[i % RESOURCE_TILES.size]
+        }.shuffled(random)
+        val fogDeck = fogHexes.mapIndexed { i, h -> FogTile(fogKinds[i], numbers[h]) }.shuffled(random)
+        fogHexes.forEach { numbers[it] = 0 }
+
         val portTypes = (
             listOf(Resource.LUMBER, Resource.BRICK, Resource.WOOL, Resource.GRAIN, Resource.ORE) + List(4) { null }
             ).shuffled(random)
@@ -129,7 +352,12 @@ object SeaBoards {
 
         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
+        // Home is the largest island that is not under the fog: nobody starts on land they cannot see.
+        val fogged = (0 until topo.islandCount).filter { island ->
+            topo.islandOf.indices.filter { topo.islandOf[it] == island }.all { terrains[it] == Terrain.FOG }
+        }.toSet()
+        val home = (0 until topo.islandCount).filter { it !in fogged }
+            .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 ->
@@ -139,6 +367,52 @@ object SeaBoards {
             } ?: 0
         } ?: sea.first()
 
-        return Generated(terrains, numbers.toList(), desert, pirate, ports, home)
+        val starts = when (scenario.start) {
+            SeaStart.HOME_ONLY -> listOf(home)
+            SeaStart.MAIN_ISLANDS -> (0 until topo.islandCount).filter { island ->
+                topo.islandOf.count { it == island } >= MAIN_ISLAND_HEXES
+            }.ifEmpty { listOf(home) }
+        }
+
+        // Tribe chips: one of each kind in turn, dealt to the marked hexes in random order.
+        val chipHexes = kinds.indices.filter { kinds[it] == 't' }
+        val chips = if (chipHexes.isEmpty()) {
+            emptyList()
+        } else {
+            val kindsOfChip = listOf(TribeChip.POINT, TribeChip.HARBOUR, TribeChip.GOLD)
+            val dealt = List(chipHexes.size) { kindsOfChip[it % kindsOfChip.size] }.shuffled(random)
+            List(terrains.size) { h -> chipHexes.indexOf(h).let { if (it < 0) TribeChip.NONE else dealt[it] } }
+        }
+        val villages = if (kinds.none { it == 'V' }) {
+            emptyList()
+        } else {
+            List(terrains.size) { h -> if (terrains[h] == Terrain.VILLAGE) VILLAGE_CLOTH else 0 }
+        }
+
+        val fortress = if (kinds.none { it == 'P' }) {
+            emptyList()
+        } else {
+            List(terrains.size) { h -> if (terrains[h] == Terrain.FORTRESS) FORTRESS_STRENGTH else 0 }
+        }
+
+        // Chests under the fog: the four rewards in turn, on hexes picked at random.
+        val chestKinds = listOf(Treasure.BRICK_WOOL_GRAIN, Treasure.CHOICE, Treasure.DEV_CARD, Treasure.ROADS)
+        val chestHexes = if (scenario == SeaScenario.TREASURE_ISLANDS || scenario == SeaScenario.OASES) {
+            fogHexes.shuffled(random).take(CHESTS)
+        } else {
+            emptyList()
+        }
+        val treasures = if (chestHexes.isEmpty()) {
+            emptyList()
+        } else {
+            List(terrains.size) { h -> chestHexes.indexOf(h).let { if (it < 0) Treasure.NONE else chestKinds[it % chestKinds.size] } }
+        }
+
+        // Canal tiles keep their number under the tile until it is dug out.
+        val canalHexes = kinds.indices.filter { kinds[it] == 'C' }
+        val canalNumbers = if (canalHexes.isEmpty()) emptyList() else List(terrains.size) { h -> if (h in canalHexes) numbers[h] else 0 }
+        canalHexes.forEach { numbers[it] = 0 }
+
+        return Generated(terrains, numbers.toList(), desert, pirate, ports, home, starts, fogDeck, chips, villages, fortress, treasures, canalNumbers)
     }
 }

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

@@ -83,7 +83,7 @@ internal object SeaRules {
             .map { sea.ships[it] }
             .filter { it != NO_PLAYER && it != thief }
             .distinct()
-            .filter { state.resourceCount(it) > 0 }
+            .filter { if (state.isCk) CatanCk.goodsCount(state, it) > 0 else state.resourceCount(it) > 0 }
     }
 
     fun pirateMoves(state: CatanState, seat: Int): List<MovePirate> {
@@ -135,25 +135,356 @@ internal object SeaRules {
         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)
+            state.copy(sea = sea.copy(gold = emptyList(), afterGold = null), phase = sea.afterGold ?: CatanPhase.PLAYING)
         } else {
             state.copy(sea = sea.copy(gold = queue), phase = CatanPhase.GOLD)
         }
     }
 
+    // -----------------------------------------------------------------------
+    // Fog
+    // -----------------------------------------------------------------------
+
+    /** Hidden hexes a piece on [edge] reaches: any that touches either end. */
+    private fun fogReached(state: CatanState, edge: Int): List<Int> {
+        val topo = state.topo
+        return topo.EDGE_VERTICES[edge].toList()
+            .flatMap { topo.VERTEX_HEXES[it] }
+            .filter { state.terrains[it] == Terrain.FOG }
+            .distinct()
+            .sorted()
+    }
+
+    /**
+     * After a road or ship lands on [edge]: turn each fog hex it now touches face up. The finder takes one card
+     * of what it yields, or chooses any resource if it is gold, supply permitting. The caller's phase is kept.
+     */
+    fun reveal(state: CatanState, seat: Int, edge: Int): CatanState {
+        var s = state
+        val found = fogReached(state, edge)
+        if (found.isEmpty()) return s
+        val owed = mutableListOf<GoldOwed>()
+        for (hex in found) {
+            val sea = s.sea!!
+            val tile = sea.fogDeck.firstOrNull() ?: break
+            val name = tile.terrain.name.lowercase()
+            s = s.copy(
+                terrains = s.terrains.toMutableList().also { it[hex] = tile.terrain },
+                numbers = s.numbers.toMutableList().also { it[hex] = tile.number },
+                sea = sea.copy(fogDeck = sea.fogDeck.drop(1)),
+                log = s.log + "Seat $seat uncovers ${if (tile.terrain == Terrain.GOLD) "a gold field" else "the $name"} " +
+                    "(${s.topo.HEXES[hex].q},${s.topo.HEXES[hex].r})" +
+                    if (tile.number != 0) " with a ${tile.number}." else ".",
+            )
+            val resource = tile.terrain.produces
+            if (resource != null && CatanRules.bankSupply(s, resource) > 0) {
+                s = s.copy(resources = CatanRules.withCounts(s.resources, seat, mapOf(resource to 1), 1))
+            } else if (tile.terrain == Terrain.GOLD) {
+                owed += GoldOwed(seat, 1)
+            }
+            val chest = s.sea!!.treasures.getOrNull(hex) ?: Treasure.NONE
+            if (chest != Treasure.NONE) {
+                val (opened, choose) = openChest(s, seat, chest)
+                s = opened
+                if (choose > 0) owed += GoldOwed(seat, choose)
+            }
+        }
+        if (owed.isEmpty()) return s
+        return owe(s, seat, owed.sumOf { it.count })
+    }
+
+    /**
+     * [seat] opens [chest]: the state after what it pays directly, and the number of cards of the seat's own
+     * choice still owed. Cards the bank cannot cover are simply not paid.
+     */
+    private fun openChest(state: CatanState, seat: Int, chest: Treasure): Pair<CatanState, Int> {
+        var s = state
+        fun pay(cards: Map<Resource, Int>) {
+            val real = cards.filter { (r, n) -> CatanRules.bankSupply(s, r) >= n }
+            if (real.isNotEmpty()) s = s.copy(resources = CatanRules.withCounts(s.resources, seat, real, 1))
+        }
+        var choose = 0
+        val said = when (chest) {
+            Treasure.BRICK_WOOL_GRAIN -> {
+                pay(mapOf(Resource.BRICK to 1, Resource.WOOL to 1, Resource.GRAIN to 1))
+                "a brick, a wool and a grain"
+            }
+            Treasure.ROADS -> {
+                pay(mapOf(Resource.LUMBER to 2, Resource.BRICK to 2))
+                "materials for two roads"
+            }
+            Treasure.DEV_CARD -> if (!s.isCk && s.devDeck.isNotEmpty()) {
+                val card = s.devDeck.first().copy(boughtTurn = s.turnNumber)
+                val hands = s.devHands.toMutableList().also { it[seat] = it[seat] + card }
+                s = s.copy(devDeck = s.devDeck.drop(1), devHands = hands, devHandCounts = hands.map { it.size })
+                "a development card"
+            } else {
+                choose = 1
+                "a resource of its choice"
+            }
+            else -> {
+                choose = 1
+                "a resource of its choice"
+            }
+        }
+        s = s.copy(log = s.log + "Seat $seat opens a treasure chest: $said.")
+        return s to choose
+    }
+
+    /** Queues [count] cards of [seat]'s choice, to be taken before play resumes where it left off. */
+    private fun owe(state: CatanState, seat: Int, count: Int): CatanState {
+        val sea = state.sea!!
+        val queued = sea.copy(
+            gold = sea.gold + GoldOwed(seat, count),
+            afterGold = state.phase.takeIf { it != CatanPhase.GOLD } ?: sea.afterGold,
+        )
+        return settleGold(state.copy(sea = queued))
+    }
+
     // -----------------------------------------------------------------------
     // 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
+    /** The bonus points [seat] holds: first landings, tribe chips, and one for every two cloth. */
+    fun bonusPoints(state: CatanState, seat: Int): Int {
+        val sea = state.sea ?: return 0
+        return sea.islandBonus.count { it == seat } * ISLAND_BONUS +
+            (sea.raidPoints.getOrNull(seat) ?: 0) +
+            (sea.wonders.getOrNull(seat) ?: 0) +
+            clothOf(state, seat) / CLOTH_PER_POINT +
+            (sea.chipPoints.getOrNull(seat) ?: 0) +
+            (sea.canalDug.getOrNull(seat) ?: 0) / CANAL_UNITS_PER_POINT
+    }
+
+    // -----------------------------------------------------------------------
+    // The Great Canal
+    // -----------------------------------------------------------------------
+
+    val DIG_COST: Map<Resource, Int> = mapOf(Resource.BRICK to 1, Resource.ORE to 1)
+
+    /** Units that finish a canal tile. */
+    const val CANAL_TILE_UNITS = 3
+
+    /** Two units dug are a victory point. */
+    const val CANAL_UNITS_PER_POINT = 2
+
+    /** Tiles [seat] may dig a unit of: unfinished, with a settlement or city of the seat's on a corner. */
+    private fun digTargets(state: CatanState, seat: Int): List<Int> {
+        val sea = state.sea!!
+        if (sea.canalUnits.isEmpty()) return emptyList()
+        return sea.canalUnits.indices.filter { h ->
+            sea.canalNumbers[h] != 0 && sea.canalUnits[h] in 0 until CANAL_TILE_UNITS &&
+                state.terrains[h] == Terrain.DESERT &&
+                state.topo.HEX_CORNERS[h].any { state.buildings[it]?.owner == seat }
+        }
+    }
+
+    fun applyDig(state: CatanState, seat: Int, move: DigCanal): CatanState {
+        val sea = state.sea!!
+        val hex = state.topo.hexIndex.getValue(move.hex)
+        val units = sea.canalUnits[hex] + 1
+        val dug = sea.canalDug.toMutableList().also { it[seat] += 1 }
+        var s = state.copy(
+            resources = CatanRules.withCounts(state.resources, seat, DIG_COST, -1),
+            sea = sea.copy(canalUnits = sea.canalUnits.toMutableList().also { it[hex] = units }, canalDug = dug),
+            log = state.log + "Seat $seat digs the canal at (${move.hex.q},${move.hex.r}): $units of $CANAL_TILE_UNITS.",
+        )
+        if (units == CANAL_TILE_UNITS) {
+            s = s.copy(
+                terrains = s.terrains.toMutableList().also { it[hex] = Terrain.FIELDS },
+                numbers = s.numbers.toMutableList().also { it[hex] = sea.canalNumbers[hex] },
+                log = s.log + "The tile is dug out: it is fields now, with a ${sea.canalNumbers[hex]}.",
+            )
+        }
+        return CatanRules.checkWin(s)
+    }
+
+    // -----------------------------------------------------------------------
+    // Cloth for Catan
+    // -----------------------------------------------------------------------
+
+    const val CLOTH_PER_POINT = 2
+
+    fun clothOf(state: CatanState, seat: Int): Int = state.sea?.cloth?.getOrNull(seat) ?: 0
+
+    /**
+     * After the dice pay: every village showing [number] pays one cloth to each settlement or city beside it
+     * (a city is not worth more here), until its stock runs out. A robber on the village stops it.
+     */
+    fun payCloth(state: CatanState, number: Int): CatanState {
+        val sea = state.sea ?: return state
+        if (sea.villageCloth.isEmpty()) return state
+        var s = state
+        val topo = state.topo
+        for (h in 0 until topo.HEX_COUNT) {
+            if (state.terrains[h] != Terrain.VILLAGE || state.numbers[h] != number || h == state.robber) continue
+            val takers = topo.HEX_CORNERS[h].mapNotNull { state.buildings[it]?.owner }
+            if (takers.isEmpty()) continue
+            // Seats in turn order from the roller get the last of the stock.
+            val order = takers.sortedBy { (it - state.turn + state.playerCount) % state.playerCount }
+            val current = s.sea!!
+            var stock = current.villageCloth[h]
+            val cloth = current.cloth.toMutableList()
+            val said = mutableListOf<String>()
+            for (seat in order) {
+                if (stock == 0) break
+                cloth[seat] += 1
+                stock--
+                said += "seat $seat"
+            }
+            if (said.isEmpty()) continue
+            val stocks = current.villageCloth.toMutableList().also { it[h] = stock }
+            s = s.copy(
+                sea = current.copy(cloth = cloth, villageCloth = stocks),
+                log = s.log + "The village at (${topo.HEXES[h].q},${topo.HEXES[h].r}) pays cloth to ${said.joinToString(", ")}.",
+            )
+        }
+        return s
+    }
+
+    // -----------------------------------------------------------------------
+    // Pirate Islands
+    // -----------------------------------------------------------------------
+
+    val RAID_COST: Map<Resource, Int> = mapOf(Resource.ORE to 1, Resource.WOOL to 1, Resource.GRAIN to 1)
+
+    const val FORTRESS_POINTS = 2
+
+    /** Whether a pirate fortress still stands on the island [vertex] is part of, so nobody may settle there. */
+    fun fortressHolds(state: CatanState, vertex: Int): Boolean {
+        val sea = state.sea ?: return false
+        if (sea.fortress.isEmpty()) return false
+        val island = state.topo.vertexIsland[vertex]
+        return island >= 0 && sea.fortress.indices.any { sea.fortress[it] > 0 && state.topo.islandOf[it] == island }
+    }
+
+    /** Fortress hexes [seat] has a ship beside. */
+    private fun raidTargets(state: CatanState, seat: Int): List<Int> {
+        val sea = state.sea!!
+        if (sea.fortress.isEmpty()) return emptyList()
+        val topo = state.topo
+        return sea.fortress.indices.filter { h ->
+            sea.fortress[h] > 0 && (0 until topo.EDGE_COUNT).any { h in topo.EDGE_HEXES[it] && sea.ships[it] == seat }
+        }
+    }
+
+    fun applyRaid(state: CatanState, seat: Int, move: RaidFortress): CatanState {
+        val sea = state.sea!!
+        val hex = state.topo.hexIndex.getValue(move.hex)
+        val left = sea.fortress[hex] - 1
+        var s = state.copy(resources = CatanRules.withCounts(state.resources, seat, RAID_COST, -1))
+        val strength = sea.fortress.toMutableList().also { it[hex] = left }
+        if (left > 0) {
+            return s.copy(
+                sea = sea.copy(fortress = strength),
+                log = s.log + "Seat $seat raids the fortress at (${move.hex.q},${move.hex.r}); $left strength left.",
+            )
+        }
+        val points = sea.raidPoints.ifEmpty { List(state.playerCount) { 0 } }.toMutableList().also { it[seat] += FORTRESS_POINTS }
+        s = s.copy(
+            terrains = s.terrains.toMutableList().also { it[hex] = Terrain.DESERT },
+            sea = sea.copy(fortress = strength, raidPoints = points),
+            log = s.log + "Seat $seat takes the fortress at (${move.hex.q},${move.hex.r}): +$FORTRESS_POINTS victory points, " +
+                "and the island is open.",
+        )
+        return CatanRules.checkWin(s)
+    }
+
+    // -----------------------------------------------------------------------
+    // Wonders of Catan
+    // -----------------------------------------------------------------------
+
+    /** What each of the four stages of a wonder costs. */
+    val WONDER_STAGES: List<Map<Resource, Int>> = listOf(
+        mapOf(Resource.BRICK to 2, Resource.LUMBER to 1, Resource.GRAIN to 1),
+        mapOf(Resource.BRICK to 1, Resource.ORE to 2, Resource.WOOL to 1),
+        mapOf(Resource.ORE to 3, Resource.GRAIN to 1, Resource.LUMBER to 1),
+        mapOf(Resource.ORE to 3, Resource.GRAIN to 2, Resource.BRICK to 1),
+    )
+
+    /** The next stage [seat] could build, if the scenario has wonders and the seat has a city to raise it in. */
+    private fun nextStage(state: CatanState, seat: Int): Map<Resource, Int>? {
+        val stage = state.sea?.wonders?.getOrNull(seat) ?: return null
+        if (stage >= WONDER_STAGES.size) return null
+        if (state.buildings.none { it?.owner == seat && it.type == BuildingType.CITY }) return null
+        return WONDER_STAGES[stage]
+    }
+
+    /** The extra moves a scenario offers during play: raids and wonder stages. */
+    fun scenarioMoves(state: CatanState, seat: Int): List<CatanMove> {
+        val moves = mutableListOf<CatanMove>()
+        if (CatanRules.affordable(state, seat, RAID_COST)) {
+            raidTargets(state, seat).forEach { moves += RaidFortress(state.topo.HEXES[it]) }
+        }
+        if (CatanRules.affordable(state, seat, DIG_COST)) {
+            digTargets(state, seat).forEach { moves += DigCanal(state.topo.HEXES[it]) }
+        }
+        nextStage(state, seat)?.let { if (CatanRules.affordable(state, seat, it)) moves += BuildWonder }
+        return moves
+    }
+
+    fun applyWonder(state: CatanState, seat: Int): CatanState {
+        val sea = state.sea!!
+        val stage = sea.wonders[seat] + 1
+        val built = sea.wonders.toMutableList().also { it[seat] = stage }
+        val s = state.copy(
+            resources = CatanRules.withCounts(state.resources, seat, WONDER_STAGES[stage - 1], -1),
+            sea = sea.copy(wonders = built),
+            log = state.log + "Seat $seat builds stage $stage of a wonder.",
+        )
+        if (stage < WONDER_STAGES.size) return CatanRules.checkWin(s)
+        return s.copy(
+            phase = CatanPhase.GAME_OVER,
+            winner = seat,
+            log = s.log + "Seat $seat completes a wonder of Catan and wins.",
+        )
+    }
+
+    // -----------------------------------------------------------------------
+    // The Forgotten Tribe
+    // -----------------------------------------------------------------------
+
+    /** After a settlement on [vertex]: take any tribe chip lying on a hex beside it. */
+    fun takeChips(state: CatanState, seat: Int, vertex: Int): CatanState {
+        var s = state
+        if (s.sea?.chips.isNullOrEmpty()) return s
+        var gold = 0
+        for (hex in state.topo.VERTEX_HEXES[vertex]) {
+            val sea = s.sea!!
+            val chip = sea.chips.getOrNull(hex) ?: continue
+            if (chip == TribeChip.NONE) continue
+            val rest = sea.chips.toMutableList().also { it[hex] = TribeChip.NONE }
+            var next = sea.copy(chips = rest)
+            val said = when (chip) {
+                TribeChip.POINT -> {
+                    val points = next.chipPoints.ifEmpty { List(state.playerCount) { 0 } }.toMutableList()
+                    points[seat] += 1
+                    next = next.copy(chipPoints = points)
+                    "a victory point"
+                }
+                TribeChip.HARBOUR -> {
+                    next = next.copy(harbourSeats = (next.harbourSeats + seat).distinct())
+                    "a harbour that trades 3:1"
+                }
+                else -> {
+                    gold += 2
+                    "two resources of its choice"
+                }
+            }
+            s = s.copy(sea = next, log = s.log + "Seat $seat takes the tribe's chip beside it: $said.")
+        }
+        return if (gold > 0) owe(s, seat, gold) else s
+    }
+
+    /** What happens to a new settlement of [seat]'s on [vertex] beyond the base game. */
+    fun settled(state: CatanState, seat: Int, vertex: Int): CatanState =
+        takeChips(claimIsland(state, seat, vertex), seat, vertex)
 
     /** 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
+        if (island < 0 || sea.isStart(island) || sea.islandBonus[island] != NO_PLAYER) return state
         val bonus = sea.islandBonus.toMutableList().also { it[island] = seat }
         return state.copy(
             sea = sea.copy(islandBonus = bonus),

app/src/main/java/org/prolibertate/games/game/checkers/CheckersAi.kt

@@ -1,6 +1,9 @@
 package org.prolibertate.games.game.checkers
 
 import kotlin.random.Random
+import kotlin.math.roundToInt
+import org.prolibertate.games.game.engine.AiLevel
+import org.prolibertate.games.game.engine.AiProfiles
 import org.prolibertate.games.game.engine.GameAi
 
 /**
@@ -17,22 +20,49 @@ import org.prolibertate.games.game.engine.GameAi
  * recapture as its only legal move, so the search plays it whether it wanted to
  * or not.
  */
-class CheckersAi(private val level: CheckersLevel? = null) :
-    GameAi<CheckersState, CheckersMove> {
+class CheckersAi(
+    private val profiles: AiProfiles = AiProfiles.DEFAULT,
+    private val level: CheckersLevel? = null,
+) : GameAi<CheckersState, CheckersMove> {
 
     private var nodeBudget = 0
     private var nodesUsed = 0
 
+    // Evaluation weights and viewpoint for the move being chosen. At the default
+    // (balanced) style they equal the plain constants, so Medium is unchanged.
+    private var rootSeat = 0
+    private var wAdvance = ADVANCE
+    private var wEdge = EDGE
+    private var wBackRow = BACK_ROW
+    private var wTheirMobility = MOBILITY
+
     override fun chooseMove(
         state: CheckersState,
         seat: Int,
         legal: List<CheckersMove>,
     ): CheckersMove {
         require(legal.isNotEmpty()) { "No legal move for seat $seat" }
+        val profile = profiles.of(seat)
         val setting = level ?: state.options.level
         if (legal.size == 1) return legal.first()
 
-        nodeBudget = NODE_BUDGET
+        val bold = profile.style.boldness
+        val spite = profile.style.spite
+        rootSeat = seat
+        // Bold seats push men forward and care less about the edge and back row;
+        // cautious ones do the reverse. Spiteful seats weigh the opponent's
+        // freedom of movement more heavily.
+        wAdvance = ADVANCE + (bold * 2).roundToInt()
+        wEdge = EDGE - (bold * 2).roundToInt()
+        wBackRow = BACK_ROW - (bold * 3).roundToInt()
+        wTheirMobility = MOBILITY + (spite * 2).roundToInt()
+
+        val maxDepth = when (profile.level) {
+            AiLevel.EASY -> maxOf(2, setting.depth - 2)
+            AiLevel.MEDIUM -> setting.depth
+            AiLevel.HARD -> setting.depth + 2
+        }
+        nodeBudget = if (profile.level == AiLevel.HARD) HARD_NODE_BUDGET else NODE_BUDGET
         nodesUsed = 0
 
         val random = Random(state.moveLog.size * 31L + state.positionKey().hashCode())
@@ -40,7 +70,7 @@ class CheckersAi(private val level: CheckersLevel? = null) :
         var best = legal.first()
         var scored = legal.map { it to 0 }
 
-        for (depth in 1..setting.depth) {
+        for (depth in 1..maxDepth) {
             val results = mutableListOf<Pair<CheckersMove, Int>>()
             val ordered = order(legal, preferred = best)
             for (move in ordered) {
@@ -61,7 +91,16 @@ class CheckersAi(private val level: CheckersLevel? = null) :
 
         val bestScore = scored.maxOf { it.second }
         val acceptable = scored.filter { it.second >= bestScore - setting.slack() }
-        return acceptable[random.nextInt(acceptable.size)].first
+        val chosen = acceptable[random.nextInt(acceptable.size)].first
+        if (profile.level != AiLevel.EASY) return chosen
+
+        // Easy now and then settles for another sound-looking move: only ones
+        // within a man and a half of the best, never a real blunder.
+        val ranked = listOf(chosen) + scored
+            .filter { it.first != chosen && it.second >= bestScore - EASY_TOLERANCE }
+            .sortedByDescending { it.second }
+            .map { it.first }
+        return profile.pick(ranked)
     }
 
     private fun CheckersLevel.slack(): Int = when (this) {
@@ -126,29 +165,32 @@ class CheckersAi(private val level: CheckersLevel? = null) :
      */
     private fun evaluate(state: CheckersState): Int {
         val us = state.turn
-        val them = other(us)
         var score = 0
+        val me = rootSeat
 
         for (square in 0 until SQUARES) {
             val piece = state.board[square] ?: continue
-            val sign = if (piece.seat == us) 1 else -1
+            val sign = if (piece.seat == me) 1 else -1
             score += sign * if (piece.king) KING else MAN
 
             if (!piece.king) {
                 // How many rows it has come, out of the seven it needs.
                 val advanced = if (piece.seat == BLACK_SEAT) rowOf(square) else 7 - rowOf(square)
-                score += sign * advanced * ADVANCE
+                score += sign * advanced * wAdvance
             }
 
             // Sitting on the edge cannot be jumped, which is worth a little in
             // a game whose entire tactic is being jumped.
-            if (columnOf(square) == 0 || columnOf(square) == 7) score += sign * EDGE
+            if (columnOf(square) == 0 || columnOf(square) == 7) score += sign * wEdge
 
-            if (rowOf(square) == crownRowOf(other(piece.seat))) score += sign * BACK_ROW
+            if (rowOf(square) == crownRowOf(other(piece.seat))) score += sign * wBackRow
         }
 
-        score += MOBILITY * (mobility(state, us) - mobility(state, them))
-        return score
+        val mine = mobility(state, me)
+        val theirs = mobility(state, other(me))
+        score += MOBILITY * mine - wTheirMobility * theirs
+        // Scored from the root seat's side; flip for the side to move.
+        return if (us == me) score else -score
     }
 
     /**
@@ -178,6 +220,8 @@ class CheckersAi(private val level: CheckersLevel? = null) :
         const val INFINITY = 1_000_000
         const val WIN = 100_000
         const val NODE_BUDGET = 200_000
+        const val HARD_NODE_BUDGET = 450_000
+        const val EASY_TOLERANCE = 150
 
         const val MAN = 100
         const val KING = 175

app/src/main/java/org/prolibertate/games/game/chess/ChessAi.kt

@@ -2,6 +2,9 @@ package org.prolibertate.games.game.chess
 
 import kotlin.math.abs
 import kotlin.random.Random
+import org.prolibertate.games.game.engine.AiLevel
+import org.prolibertate.games.game.engine.AiProfile
+import org.prolibertate.games.game.engine.AiProfiles
 import org.prolibertate.games.game.engine.GameAi
 
 /**
@@ -16,7 +19,14 @@ import org.prolibertate.games.game.engine.GameAi
  * so the setup screen sets the strength without the caller having to thread it
  * through.
  */
-class ChessAi(private val level: ChessLevel? = null) : GameAi<ChessState, ChessMove> {
+class ChessAi(private val profiles: AiProfiles = AiProfiles.DEFAULT) : GameAi<ChessState, ChessMove> {
+
+    /** Fixed strength that overrides the table's option (used by tests and tools). */
+    private var level: ChessLevel? = null
+
+    constructor(level: ChessLevel) : this(AiProfiles.DEFAULT) {
+        this.level = level
+    }
 
     /**
      * Ceiling on how much thinking any one move gets. A phone should not stall
@@ -28,10 +38,22 @@ class ChessAi(private val level: ChessLevel? = null) : GameAi<ChessState, ChessM
 
     override fun chooseMove(state: ChessState, seat: Int, legal: List<ChessMove>): ChessMove {
         require(legal.isNotEmpty()) { "No legal move for seat $seat" }
+        val profile = profiles.of(seat)
         val setting = level ?: state.options.level
         if (legal.size == 1) return legal.first()
 
-        nodeBudget = NODE_BUDGET
+        // Easy looks one move less far ahead; Hard looks one further and gets
+        // roughly twice the node budget (still a couple of seconds on a phone).
+        val maxDepth = when (profile.level) {
+            AiLevel.EASY -> maxOf(1, setting.depth - 1)
+            AiLevel.MEDIUM -> setting.depth
+            AiLevel.HARD -> setting.depth + 1
+        }
+        nodeBudget = if (profile.level == AiLevel.HARD) HARD_NODE_BUDGET else NODE_BUDGET
+        aiWhite = state.whiteToMove
+        styleActive = profile.style.boldness != 0.0 || profile.style.spite != 0.0
+        styleBoldness = profile.style.boldness
+        styleSpite = profile.style.spite
         nodesUsed = 0
 
         // Deterministic per position, so a host and a client replaying the same
@@ -42,7 +64,7 @@ class ChessAi(private val level: ChessLevel? = null) : GameAi<ChessState, ChessM
         var best = legal.first()
         var scored = legal.map { it to 0 }
 
-        for (depth in 1..setting.depth) {
+        for (depth in 1..maxDepth) {
             val results = mutableListOf<Pair<ChessMove, Int>>()
             // Search the previous iteration's best first, so the sub-searches
             // below it have a decent bound to prune against.
@@ -74,9 +96,56 @@ class ChessAi(private val level: ChessLevel? = null) : GameAi<ChessState, ChessM
         // makes them beatable without making them play nonsense.
         val bestScore = scored.maxOf { it.second }
         val acceptable = scored.filter { it.second >= bestScore - setting.slack() }
-        return acceptable[random.nextInt(acceptable.size)].first
+        val chosen = acceptable[random.nextInt(acceptable.size)].first
+        if (profile.level != AiLevel.EASY) return chosen
+
+        // Easy sometimes settles for a worse move, but only one within a modest
+        // margin of the best, so it never throws a piece away or walks into mate.
+        val ranked = scored.filter { it.second >= bestScore - setting.slack() - EASY_EXTRA_SLACK }
+            .sortedByDescending { it.second }.map { it.first }
+        val ordered = listOf(chosen) + ranked.filter { it != chosen }
+        return profile.pick(ordered)
     }
 
+    // Per-move style state, set at the start of chooseMove.
+    private var aiWhite = true
+    private var styleActive = false
+    private var styleBoldness = 0.0
+    private var styleSpite = 0.0
+
+    /**
+     * A small temperament term (well under a pawn) from the mover's point of
+     * view. Aggressive seats like pieces near the enemy king, cautious seats
+     * like a sheltered own king, spiteful seats like the enemy being badly
+     * placed. Zero for the default style, so default play is unchanged.
+     */
+    private fun styleTerm(state: ChessState): Int {
+        val enemyKing = state.kingSquare(white = !aiWhite)
+        val myKing = state.kingSquare(white = aiWhite)
+        var attackers = 0
+        var shield = 0
+        var enemyPlacement = 0
+        for (square in 0 until 64) {
+            val piece = state.board[square] ?: continue
+            if (piece.white == aiWhite) {
+                if (piece.kind == PieceKind.KING) continue
+                if (enemyKing != null && piece.kind != PieceKind.PAWN && distance(square, enemyKing) <= 3) attackers++
+                if (myKing != null && distance(square, myKing) <= 1) shield++
+            } else {
+                val table = tableFor(piece.kind)
+                enemyPlacement += table[if (piece.white) square else square xor 56]
+            }
+        }
+        var term = 0.0
+        if (styleBoldness > 0) term += styleBoldness * 4 * attackers
+        if (styleBoldness < 0) term += -styleBoldness * 5 * shield
+        term -= styleSpite * 0.1 * enemyPlacement
+        val own = term.toInt().coerceIn(-40, 40)
+        return if (state.whiteToMove == aiWhite) own else -own
+    }
+
+    private fun distance(a: Int, b: Int): Int = maxOf(abs(fileOf(a) - fileOf(b)), abs(rankOf(a) - rankOf(b)))
+
     private fun ChessLevel.slack(): Int = when (this) {
         ChessLevel.CASUAL -> 70
         ChessLevel.CLUB -> 20
@@ -116,7 +185,7 @@ class ChessAi(private val level: ChessLevel? = null) : GameAi<ChessState, ChessM
      */
     private fun quiescence(state: ChessState, alpha: Int, beta: Int, ply: Int): Int {
         nodesUsed++
-        val standPat = evaluate(state)
+        val standPat = evaluate(state) + if (styleActive) styleTerm(state) else 0
         if (standPat >= beta) return beta
         var localAlpha = maxOf(alpha, standPat)
         if (ply >= MAX_QUIESCENCE_PLY) return localAlpha
@@ -205,6 +274,8 @@ class ChessAi(private val level: ChessLevel? = null) : GameAi<ChessState, ChessM
         const val INFINITY = 1_000_000
         const val MATE = 100_000
         const val NODE_BUDGET = 120_000
+        const val HARD_NODE_BUDGET = 240_000
+        const val EASY_EXTRA_SLACK = 60
         const val MAX_QUIESCENCE_PLY = 24
 
         /**

app/src/main/java/org/prolibertate/games/game/crazyeights/CrazyEightsAi.kt

@@ -1,52 +1,135 @@
 package org.prolibertate.games.game.crazyeights
 
+import org.prolibertate.games.game.cards.Card
+import org.prolibertate.games.game.cards.Rank
 import org.prolibertate.games.game.cards.Suit
+import org.prolibertate.games.game.engine.AiLevel
+import org.prolibertate.games.game.engine.AiProfile
+import org.prolibertate.games.game.engine.AiProfiles
 import org.prolibertate.games.game.engine.GameAi
 
 /**
- * A heuristic Crazy 8s opponent.
+ * A Crazy 8s opponent whose strength and temperament come from the seat's profile.
  *
- * It sheds expensive cards first, keeps its eights back for when it is stuck,
- * and when it does play one it names the suit it holds most of.
+ * MEDIUM (the default) sheds expensive cards first, keeps its eights back for
+ * when it is stuck, and when it does play one it names the suit it holds most of.
+ *
+ * EASY plays the same way but sometimes sheds a cheaper card or wastes an eight.
+ * HARD counts the cards on the discard pile to know what is still out, plays to
+ * keep a long suit it can run, and when someone is close to going out it turns
+ * the game to a suit that is nearly exhausted so they cannot follow.
  */
-class CrazyEightsAi(private val difficulty: Difficulty = Difficulty.NORMAL) :
+class CrazyEightsAi(private val profiles: AiProfiles = AiProfiles.DEFAULT) :
     GameAi<CrazyEightsState, CrazyEightsMove> {
 
-    enum class Difficulty(
-        /** Play an eight anyway once the hand is down to this size. */
-        val eightEndgame: Int,
-    ) {
-        EASY(eightEndgame = 99),
-        NORMAL(eightEndgame = 3),
-        CAUTIOUS(eightEndgame = 2),
-    }
-
     override fun chooseMove(
         state: CrazyEightsState,
         seat: Int,
         legal: List<CrazyEightsMove>,
     ): CrazyEightsMove {
         require(legal.isNotEmpty()) { "No legal move for seat $seat" }
+        val profile = profiles.of(seat)
         val plays = legal.filterIsInstance<PlayCard>()
         if (plays.isEmpty()) return legal.first()
 
+        val move: CrazyEightsMove = when (profile.level) {
+            AiLevel.MEDIUM -> standardRanking(state, seat, plays, EIGHT_ENDGAME).first()
+            AiLevel.EASY -> profile.pick(standardRanking(state, seat, plays, EASY_EIGHT_ENDGAME))
+            AiLevel.HARD -> hard(state, seat, plays, profile)
+        }
+        return if (move in legal) move else legal.first()
+    }
+
+    /**
+     * Ordinary cards first, most expensive leading, then eights with the suit
+     * this hand holds most of named first.
+     */
+    private fun standardRanking(
+        state: CrazyEightsState,
+        seat: Int,
+        plays: List<PlayCard>,
+        eightEndgame: Int,
+    ): List<PlayCard> {
         val hand = state.hands[seat]
         val ordinary = plays.filter { !isWild(it.card) }
 
         // An eight is the only card that always plays, so it is worth more held
         // than spent — unless the hand is nearly gone, or nothing else works.
-        val useEight = ordinary.isEmpty() || hand.size <= difficulty.eightEndgame
+        val useEight = ordinary.isEmpty() || hand.size <= eightEndgame
         val pool = if (useEight) plays else ordinary
 
-        val best = pool
-            .filter { !isWild(it.card) }
-            .maxByOrNull { crazyEightsPenalty(it.card) }
-
-        if (best != null) return best
+        val ranked = pool.filter { !isWild(it.card) }.sortedByDescending { crazyEightsPenalty(it.card) }
+        if (ranked.isNotEmpty() && !useEight) return ranked
 
         // Playing an eight: switch the game to whatever we hold most of.
-        val strongest = Suit.entries.maxByOrNull { suit -> hand.count { it.suit == suit } }
-            ?: Suit.SPADES
-        return pool.firstOrNull { it.nominatedSuit == strongest } ?: pool.first()
+        val suits = Suit.entries.sortedByDescending { suit -> hand.count { it.suit == suit } }
+        val wilds = suits.flatMap { suit -> pool.filter { isWild(it.card) && it.nominatedSuit == suit } }
+        return ranked + wilds.ifEmpty { pool.filter { isWild(it.card) } }
+    }
+
+    // -----------------------------------------------------------------------
+    // Hard
+    // -----------------------------------------------------------------------
+
+    private fun hard(
+        state: CrazyEightsState,
+        seat: Int,
+        plays: List<PlayCard>,
+        profile: AiProfile,
+    ): CrazyEightsMove {
+        val hand = state.hands[seat]
+        val options = state.options
+
+        // Cards this seat can account for: its own hand and everything on the pile.
+        val known = HashSet<Card>().also { it.addAll(hand); it.addAll(state.discard) }
+        val unseen = FULL_DECK.filter { it !in known }
+        fun unseenIn(suit: Suit): Int = unseen.count { it.suit == suit }
+
+        val next = (seat + 1) % options.playerCount
+        val nextCount = state.handCounts[next]
+        val smallestOpponent = (0 until options.playerCount).filter { it != seat }
+            .minOf { state.handCounts[it] }
+        // How hard to squeeze the suits: more when somebody is about to go out.
+        val urgency = 1.0 + profile.style.spite +
+            (if (nextCount <= 2) 1.0 else 0.0) + (if (smallestOpponent <= 2) 0.5 else 0.0)
+
+        /** Value of leaving the game showing [suit], with [remaining] the cards still held. */
+        fun suitValue(suit: Suit, remaining: List<Card>): Double =
+            3.0 * remaining.count { it.suit == suit } - 0.7 * urgency * unseenIn(suit)
+
+        val ordinary = plays.filter { !isWild(it.card) }
+        val wilds = plays.filter { isWild(it.card) }
+
+        // Aggressive seats spend eights earlier; cautious ones keep them as insurance.
+        val endgame = (EIGHT_ENDGAME + profile.style.boldness * 2.0)
+        val blocking = smallestOpponent <= 1 || (nextCount <= 2 && urgency >= 2.0)
+        val useEight = ordinary.isEmpty() || hand.size <= endgame || (blocking && wilds.isNotEmpty())
+
+        if (hand.size == 1) {
+            plays.firstOrNull()?.let { return it }
+        }
+
+        if (!useEight || wilds.isEmpty()) {
+            if (ordinary.isNotEmpty()) {
+                // Cautious seats shed liabilities harder, bold ones care more about position.
+                val shedWeight = 1.0 - 0.3 * profile.style.boldness
+                return ordinary.maxBy { play ->
+                    val remaining = hand - play.card
+                    crazyEightsPenalty(play.card) * shedWeight + suitValue(play.card.suit, remaining)
+                }
+            }
+        }
+
+        // An eight: name the suit that is best for this hand and worst for the others.
+        return wilds.maxBy { play ->
+            val remaining = hand - play.card
+            suitValue(play.nominatedSuit ?: play.card.suit, remaining)
+        }
+    }
+
+    private companion object {
+        const val EIGHT_ENDGAME = 3
+        const val EASY_EIGHT_ENDGAME = 99
+        val FULL_DECK: List<Card> = Suit.entries.flatMap { suit -> Rank.standard.map { Card(it, suit) } }
     }
 }

app/src/main/java/org/prolibertate/games/game/cribbage/CribbageAi.kt

@@ -3,8 +3,12 @@ package org.prolibertate.games.game.cribbage
 import org.prolibertate.games.game.cards.Card
 import org.prolibertate.games.game.cards.Decks
 import org.prolibertate.games.game.cards.Rank
+import org.prolibertate.games.game.engine.AiLevel
+import org.prolibertate.games.game.engine.AiProfile
+import org.prolibertate.games.game.engine.AiProfiles
 import org.prolibertate.games.game.engine.GameAi
 import kotlin.math.abs
+import kotlin.random.Random
 
 /**
  * A cribbage opponent that counts rather than guesses.
@@ -18,8 +22,14 @@ import kotlin.math.abs
  *
  * The play is a heuristic: take the points on offer, and try not to leave the
  * count where a ten-card collects fifteen or thirty-one.
+ *
+ * Per seat, from [profiles]: Easy settles for a worse lay-away or card now and
+ * then; Hard also samples the crib (what the unseen cards might add to it) and
+ * weighs what a reply could score off each card it plays. Boldness trades the
+ * two counts-to-avoid and crib ownership; spite weighs the other side's crib.
  */
-class CribbageAi : GameAi<CribbageState, CribbageMove> {
+class CribbageAi(private val profiles: AiProfiles = AiProfiles.DEFAULT) :
+    GameAi<CribbageState, CribbageMove> {
 
     override fun chooseMove(
         state: CribbageState,
@@ -27,30 +37,78 @@ class CribbageAi : GameAi<CribbageState, CribbageMove> {
         legal: List<CribbageMove>,
     ): CribbageMove {
         require(legal.isNotEmpty()) { "No legal move for seat $seat" }
+        val profile = profiles.of(seat)
         val layAways = legal.filterIsInstance<LayAway>()
-        if (layAways.isNotEmpty()) return chooseLayAway(state, seat, layAways)
-        return choosePeg(state, legal.filterIsInstance<PegCard>())
+        if (layAways.isNotEmpty()) return chooseLayAway(state, seat, layAways, profile)
+        val pegs = legal.filterIsInstance<PegCard>()
+        if (pegs.isNotEmpty()) return choosePeg(state, seat, pegs, profile)
+        return legal.first()
     }
 
     private fun chooseLayAway(
         state: CribbageState,
         seat: Int,
         choices: List<LayAway>,
+        profile: AiProfile,
     ): LayAway {
         val hand = state.hands[seat]
         val held = hand.toSet()
         val unseen = Decks.standard52().filter { it !in held }
         // A partner's crib is your crib. That is the whole of four-handed play.
         val ownCrib = state.options.teamOf(seat) == state.options.teamOf(state.dealer)
+        val boldness = profile.style.boldness
+        // Bold seats back their own crib; careful ones fear the other side's.
+        val cribSign = if (ownCrib) {
+            1.0 + 0.25 * boldness
+        } else {
+            -(1.0 - 0.25 * boldness + 0.3 * profile.style.spite)
+        }
+        val trials = if (profile.level == AiLevel.HARD) sampleCribs(hand, unseen, state.options) else null
 
-        return choices.maxByOrNull { choice ->
+        val scored = choices.map { choice ->
             val given = choice.cards.toSet()
             val keep = hand.filter { it !in given }
             val expected = unseen.sumOf { starter ->
                 CribbageScoring.show(keep, starter, isCrib = false).sumOf { it.points }
             }.toDouble() / unseen.size
-            expected + cribValue(choice.cards) * (if (ownCrib) 1.0 else -1.0)
-        } ?: choices.first()
+            val crib = if (trials != null) {
+                // Heuristic and sampled estimates agree on direction; averaging
+                // them smooths the sampling noise without losing the structure.
+                (sampledCribValue(choice.cards, trials) + cribValue(choice.cards)) / 2.0
+            } else {
+                cribValue(choice.cards)
+            }
+            choice to expected + crib * cribSign
+        }
+        // Stable sort: ties resolve to the first choice, as maxByOrNull did.
+        val ranked = scored.sortedByDescending { it.second }.map { it.first }
+        return profile.pick(ranked)
+    }
+
+    /** Sets of unseen cards a crib might receive, plus a cut, for Hard to average over. */
+    private fun sampleCribs(
+        hand: List<Card>,
+        unseen: List<Card>,
+        options: CribbageOptions,
+    ): List<List<Card>> {
+        val random = Random(hand.sumOf { it.rank.ordinal * 4 + it.suit.ordinal }.toLong())
+        // Whatever the crib is short of after our own cards, plus the cut.
+        val others = (CRIB_SIZE - options.layAwaySize).coerceAtLeast(0)
+        return List(CRIB_SAMPLES) {
+            val picked = LinkedHashSet<Card>()
+            while (picked.size < others + 1) picked += unseen[random.nextInt(unseen.size)]
+            picked.toList()
+        }
+    }
+
+    private fun sampledCribValue(given: List<Card>, trials: List<List<Card>>): Double {
+        var total = 0
+        for (trial in trials) {
+            val starter = trial.last()
+            val crib = given + trial.dropLast(1)
+            total += CribbageScoring.show(crib, starter, isCrib = true).sumOf { it.points }
+        }
+        return total.toDouble() / trials.size
     }
 
     /**
@@ -83,22 +141,63 @@ class CribbageAi : GameAi<CribbageState, CribbageMove> {
         return value
     }
 
-    private fun choosePeg(state: CribbageState, choices: List<PegCard>): PegCard {
+    private fun choosePeg(
+        state: CribbageState,
+        seat: Int,
+        choices: List<PegCard>,
+        profile: AiProfile,
+    ): PegCard {
         val count = state.count
         val onTheTable = state.series.map { it.card }
+        val boldness = profile.style.boldness
+        // Bold seats risk leaving five or twenty-one; careful ones really avoid it.
+        val countPenalty = 3.0 - boldness * 1.5
+        val leadFivePenalty = 4.0 - boldness * 2.0
+        val hard = profile.level == AiLevel.HARD
+        // Cards a reply could come from: nothing this seat holds, has seen played or was cut.
+        val unseen = if (hard) {
+            val known = (state.remaining(seat) + state.played.map { it.card } + listOfNotNull(state.starter)).toSet()
+            Decks.standard52().filter { it !in known && it !in state.hands[seat] }
+        } else {
+            emptyList()
+        }
 
-        return choices.maxByOrNull { choice ->
-            val scored = CribbageScoring.peg(onTheTable + choice.card).sumOf { it.points }
+        val scored = choices.map { choice ->
+            val points = CribbageScoring.peg(onTheTable + choice.card).sumOf { it.points }
             val after = count + pipValue(choice.card)
-            var value = scored * 10.0
+            var value = points * 10.0
             // Five and twenty-one are the two counts to avoid leaving: any of
             // the sixteen ten-cards takes fifteen or thirty-one off them.
-            if (after == 5 || after == 21) value -= 3.0
+            if (after == 5 || after == 21) value -= countPenalty
             // Leading a five is the same present, offered first.
-            if (count == 0 && choice.card.rank == Rank.FIVE) value -= 4.0
+            if (count == 0 && choice.card.rank == Rank.FIVE) value -= leadFivePenalty
             // Big cards early. Low ones are what let you keep playing at the
             // awkward end of a series, where the last card is worth a point.
-            value + pipValue(choice.card) * 0.1
-        } ?: choices.first()
+            value += pipValue(choice.card) * 0.1
+            if (hard && unseen.isNotEmpty() && after < CRIBBAGE_LIMIT) {
+                value -= replyThreat(onTheTable + choice.card, after, unseen) * 8.0
+            }
+            choice to value
+        }
+        val ranked = scored.sortedByDescending { it.second }.map { it.first }
+        return profile.pick(ranked)
+    }
+
+    /** Average points a reply scores off [series], over the cards still unseen. */
+    private fun replyThreat(series: List<Card>, after: Int, unseen: List<Card>): Double {
+        var total = 0
+        var playable = 0
+        for (card in unseen) {
+            if (after + pipValue(card) > CRIBBAGE_LIMIT) continue
+            playable++
+            total += CribbageScoring.peg(series + card).sumOf { it.points }
+        }
+        // Nothing playable is a go for them, worth a point to whoever last played.
+        return if (playable == 0) 0.0 else total.toDouble() / unseen.size
+    }
+
+    private companion object {
+        const val CRIB_SIZE = 4
+        const val CRIB_SAMPLES = 60
     }
 }

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

@@ -0,0 +1,123 @@
+package org.prolibertate.games.game.engine
+
+import kotlinx.serialization.Serializable
+import kotlin.random.Random
+
+/** How well one computer seat plays. */
+enum class AiLevel {
+    /** Makes frequent, plausible mistakes and plays without much foresight. */
+    EASY,
+
+    /** The game's standard computer opponent. */
+    MEDIUM,
+
+    /** Plays carefully: more foresight, no deliberate mistakes. */
+    HARD,
+}
+
+/** What the person at setup chooses for the table's computer seats. */
+@Serializable
+enum class AiDifficulty(val label: String) {
+    EASY("Easy"),
+    MEDIUM("Medium"),
+    HARD("Hard"),
+
+    /** Each computer seat gets its own level, picked at random. */
+    MIXED("Mixed"),
+}
+
+/**
+ * A computer seat's temperament. Never shown to the human players: it only
+ * shapes how the AI trades off the options in front of it.
+ */
+enum class AiStyle(
+    /** -1 plays safe, +1 gambles; 0 is the game's standard balance. */
+    val boldness: Double,
+    /** How much the seat cares about stopping opponents rather than building its own position. */
+    val spite: Double,
+) {
+    BALANCED(0.0, 0.0),
+    AGGRESSIVE(0.8, 0.3),
+    CAUTIOUS(-0.8, 0.0),
+    SPOILER(0.0, 0.8),
+}
+
+/**
+ * One computer seat's level and style, and a source of randomness of its own.
+ *
+ * [DEFAULT] is the game's standard opponent: [AiLevel.MEDIUM], [AiStyle.BALANCED],
+ * and it never slips, so an AI built without a profile plays exactly as it did
+ * before profiles existed.
+ */
+class AiProfile(
+    val level: AiLevel = AiLevel.MEDIUM,
+    val style: AiStyle = AiStyle.BALANCED,
+    val random: Random = Random(0),
+) {
+    /**
+     * Whether this seat should throw away its best option this time. Only
+     * [AiLevel.EASY] does, and only some of the time, so it still plays like a
+     * person who is not concentrating rather than like a random-move generator.
+     */
+    fun slips(): Boolean = level == AiLevel.EASY && random.nextDouble() < EASY_SLIP_CHANCE
+
+    /**
+     * Picks from [ranked] (best first). Easy sometimes settles for a worse choice,
+     * drawn from the better half so it stays plausible; other levels take the best.
+     */
+    fun <T> pick(ranked: List<T>): T {
+        require(ranked.isNotEmpty()) { "Nothing to pick from" }
+        if (!slips() || ranked.size == 1) return ranked.first()
+        val pool = ranked.take(maxOf(2, (ranked.size + 1) / 2))
+        return pool[random.nextInt(pool.size)]
+    }
+
+    /** [base] nudged by this seat's boldness: a gambler raises it, a cautious seat lowers it. */
+    fun bolder(base: Double, strength: Double = 1.0): Double = base + style.boldness * strength
+
+    companion object {
+        const val EASY_SLIP_CHANCE = 0.3
+        val DEFAULT = AiProfile()
+    }
+}
+
+/**
+ * The profile for every computer seat at a table, worked out from the table's
+ * difficulty setting and its seed alone.
+ *
+ * Derived rather than stored, so a saved game, a rematch from the same config
+ * and a guest's copy of a hosted table all give the same seat the same
+ * personality without it travelling anywhere.
+ */
+class AiProfiles(
+    private val difficulty: AiDifficulty,
+    private val seed: Long,
+) {
+    private val cache = HashMap<Int, AiProfile>()
+
+    constructor(config: TableConfig) : this(config.aiDifficulty, config.seed)
+
+    @Synchronized
+    fun of(seat: Int): AiProfile = cache.getOrPut(seat) {
+        val picker = Random(seed * 31 + seat * 7919L + 17)
+        val level = when (difficulty) {
+            AiDifficulty.EASY -> AiLevel.EASY
+            AiDifficulty.MEDIUM -> AiLevel.MEDIUM
+            AiDifficulty.HARD -> AiLevel.HARD
+            AiDifficulty.MIXED -> AiLevel.entries[picker.nextInt(AiLevel.entries.size)]
+        }
+        // The standard opponent is balanced by definition; the others each get a
+        // temperament, so no two computer seats feel alike.
+        val style = if (difficulty == AiDifficulty.MEDIUM) {
+            AiStyle.BALANCED
+        } else {
+            AiStyle.entries[picker.nextInt(AiStyle.entries.size)]
+        }
+        AiProfile(level, style, Random(picker.nextLong()))
+    }
+
+    companion object {
+        /** Standard opponents, for a caller that has no table to ask. */
+        val DEFAULT = AiProfiles(AiDifficulty.MEDIUM, 0L)
+    }
+}

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

@@ -43,6 +43,8 @@ data class TableConfig(
     val optionsJson: String,
     /** Shared shuffle seed so a hand is reproducible from its state. */
     val seed: Long,
+    /** How hard the computer seats play. Old saves and old hosts omit it and get the standard opponent. */
+    val aiDifficulty: AiDifficulty = AiDifficulty.MEDIUM,
 )
 
 /**

app/src/main/java/org/prolibertate/games/game/euchre/EuchreAi.kt

@@ -3,6 +3,10 @@ package org.prolibertate.games.game.euchre
 import org.prolibertate.games.game.cards.Card
 import org.prolibertate.games.game.cards.Rank
 import org.prolibertate.games.game.cards.Suit
+import org.prolibertate.games.game.cards.Decks
+import org.prolibertate.games.game.engine.AiLevel
+import org.prolibertate.games.game.engine.AiProfile
+import org.prolibertate.games.game.engine.AiProfiles
 import org.prolibertate.games.game.engine.GameAi
 
 /**
@@ -13,7 +17,7 @@ import org.prolibertate.games.game.engine.GameAi
  * That is enough to be a reasonable table opponent without pretending to be a
  * solver.
  */
-class EuchreAi(private val difficulty: Difficulty = Difficulty.NORMAL) :
+class EuchreAi(private val profiles: AiProfiles = AiProfiles.DEFAULT) :
     GameAi<EuchreState, EuchreMove> {
 
     /**
@@ -22,25 +26,50 @@ class EuchreAi(private val difficulty: Difficulty = Difficulty.NORMAL) :
      * means every seat bids and the card is never turned down — see
      * EuchreBiddingRateTest, which pins the resulting order-up rate.
      */
-    enum class Difficulty(val bidThreshold: Int, val aloneThreshold: Int) {
-        /** Bids loosely and plays straightforwardly. */
-        EASY(bidThreshold = 21, aloneThreshold = 32),
+    private companion object {
+        const val BID_THRESHOLD = 24.0
+        const val ALONE_THRESHOLD = 32.0
+    }
 
-        NORMAL(bidThreshold = 24, aloneThreshold = 32),
+    /** Cards this AI has watched played in the current hand, per seat it plays. */
+    private val memory = HashMap<Int, SeenCards>()
 
-        /** Bids tighter and is harder to sneak a trick past. */
-        CAUTIOUS(bidThreshold = 27, aloneThreshold = 31),
+    private class SeenCards {
+        var key: Long = Long.MIN_VALUE
+        val cards = HashSet<Card>()
+    }
+
+    /** Public information only: cards that have appeared on the table this hand. */
+    private fun observe(state: EuchreState, seat: Int): Set<Card> = synchronized(memory) {
+        val seen = memory.getOrPut(seat) { SeenCards() }
+        val key = state.seed * 1_000_003L + state.handNumber
+        if (key != seen.key || state.phase == EuchrePhase.BID_ROUND_1) {
+            seen.key = key
+            seen.cards.clear()
+        }
+        state.trick.forEach { seen.cards.add(it.card) }
+        state.completedTrick.forEach { seen.cards.add(it.card) }
+        state.turnedDown?.let { seen.cards.add(it) }
+        seen.cards.removeAll(state.hands[seat].toSet())
+        seen.cards.toSet()
     }
 
     override fun chooseMove(state: EuchreState, seat: Int, legal: List<EuchreMove>): EuchreMove {
         require(legal.isNotEmpty()) { "No legal move for seat $seat" }
-        return when (state.phase) {
-            EuchrePhase.BID_ROUND_1 -> chooseBidRound1(state, seat, legal)
-            EuchrePhase.BID_ROUND_2 -> chooseBidRound2(state, seat, legal)
-            EuchrePhase.DEALER_DISCARD -> chooseDiscard(state, legal)
-            EuchrePhase.PLAYING -> choosePlay(state, seat, legal)
-            else -> legal.first()
+        val profile = profiles.of(seat)
+        val seen = if (profile.level == AiLevel.HARD) observe(state, seat) else emptySet()
+        val move = try {
+            when (state.phase) {
+                EuchrePhase.BID_ROUND_1 -> chooseBidRound1(state, seat, legal, profile)
+                EuchrePhase.BID_ROUND_2 -> chooseBidRound2(state, seat, legal, profile)
+                EuchrePhase.DEALER_DISCARD -> chooseDiscard(state, legal, profile)
+                EuchrePhase.PLAYING -> choosePlay(state, seat, legal, profile, seen)
+                else -> legal.first()
+            }
+        } catch (e: RuntimeException) {
+            legal.first()
         }
+        return if (move in legal) move else legal.first()
     }
 
     // -----------------------------------------------------------------------
@@ -75,27 +104,61 @@ class EuchreAi(private val difficulty: Difficulty = Difficulty.NORMAL) :
         return value
     }
 
+    /** The five-card hand left after the dealer picks up [upCard] and discards the least useful card. */
+    private fun bestAfterPickup(hand: List<Card>, upCard: Card, trump: Suit): Int {
+        val six = hand + upCard
+        return six.maxOf { dropped -> handValue(six - dropped, trump) }
+    }
+
+    /** A hand worth playing without a partner: real trump length with a bower to lead it. */
+    private fun soundAlone(hand: List<Card>, trump: Suit): Boolean {
+        val trumps = hand.count { isTrumpCard(it, trump) }
+        val bower = hand.any { isRightBower(it, trump) || isLeftBower(it, trump) }
+        return trumps >= 3 && bower
+    }
+
+    /** Easy misjudges how good its hand is. */
+    private fun misjudge(value: Int, profile: AiProfile): Int =
+        if (profile.level == AiLevel.EASY) value + profile.random.nextInt(-5, 6) else value
+
     private fun chooseBidRound1(
         state: EuchreState,
         seat: Int,
         legal: List<EuchreMove>,
+        profile: AiProfile,
     ): EuchreMove {
         val upCard = state.upCard ?: return Pass
         val trump = upCard.suit
-        var hand = state.hands[seat]
+        val isDealer = seat == state.dealer
+        val partnerDealer = partnerOf(seat) == state.dealer
+        val hard = profile.level == AiLevel.HARD
 
         // If our partner is the dealer they gain the turn card, and if we are
         // the dealer we gain it ourselves — both make the hand stronger than it
         // looks. Ordering up into an opponent dealer instead hands them a card.
-        if (seat == state.dealer) hand = hand + upCard
-        var value = handValue(hand, trump)
-        if (partnerOf(seat) == state.dealer) value += 2
-        if (seat != state.dealer && partnerOf(seat) != state.dealer) value -= 2
+        val owned = if (isDealer) state.hands[seat] + upCard else state.hands[seat]
+        var value = when {
+            isDealer && hard -> bestAfterPickup(state.hands[seat], upCard, trump) + 3
+            else -> handValue(owned, trump)
+        }
+        if (partnerDealer) value += 2
+        if (!isDealer && !partnerDealer) {
+            value -= 2
+            // An opposing dealer who picks up a jack gets a bower out of our bid.
+            if (hard && upCard.rank == Rank.JACK) value -= 2
+        }
+        value = misjudge(value, profile)
+
+        val bidThreshold = profile.bolder(BID_THRESHOLD, -3.0)
+        var aloneThreshold = profile.bolder(ALONE_THRESHOLD, -3.0)
+        if (profile.level == AiLevel.EASY) aloneThreshold += 4.0
 
         val alone = OrderUp(alone = true)
-        if (value >= difficulty.aloneThreshold && legal.contains(alone)) return alone
+        if (value >= aloneThreshold && legal.contains(alone) && (!hard || soundAlone(owned, trump))) {
+            return alone
+        }
         val order = OrderUp(alone = false)
-        if (value >= difficulty.bidThreshold && legal.contains(order)) return order
+        if (value >= bidThreshold && legal.contains(order)) return order
         return if (legal.contains(Pass)) Pass else legal.first()
     }
 
@@ -103,37 +166,64 @@ class EuchreAi(private val difficulty: Difficulty = Difficulty.NORMAL) :
         state: EuchreState,
         seat: Int,
         legal: List<EuchreMove>,
+        profile: AiProfile,
     ): EuchreMove {
         val hand = state.hands[seat]
         val callable = legal.filterIsInstance<CallTrump>()
         if (callable.isEmpty()) return legal.first()
+        val plain = callable.filter { !it.alone }
 
-        val best = callable
-            .filter { !it.alone }
-            .maxByOrNull { handValue(hand, it.suit) }
-            ?: callable.first()
-        val bestValue = handValue(hand, best.suit)
+        val best: CallTrump
+        val bestValue: Int
+        if (profile.level == AiLevel.EASY) {
+            val noisy = plain.associateWith { handValue(hand, it.suit) + profile.random.nextInt(-5, 6) }
+            val ranked = plain.sortedByDescending { noisy.getValue(it) }
+            best = if (ranked.isEmpty()) callable.first() else profile.pick(ranked)
+            bestValue = noisy[best] ?: handValue(hand, best.suit)
+        } else {
+            best = plain.maxByOrNull { handValue(hand, it.suit) } ?: callable.first()
+            bestValue = handValue(hand, best.suit)
+        }
+
+        val bidThreshold = profile.bolder(BID_THRESHOLD, -3.0)
+        var aloneThreshold = profile.bolder(ALONE_THRESHOLD, -3.0)
+        if (profile.level == AiLevel.EASY) aloneThreshold += 4.0
 
         val alone = callable.firstOrNull { it.alone && it.suit == best.suit }
-        if (alone != null && bestValue >= difficulty.aloneThreshold) return alone
-        if (bestValue >= difficulty.bidThreshold) return best
+        val alonePlausible = profile.level != AiLevel.HARD || soundAlone(hand, best.suit)
+        if (alone != null && bestValue >= aloneThreshold && alonePlausible) return alone
+        if (bestValue >= bidThreshold) return best
         // Stuck as dealer with a bad hand: name the least-bad suit anyway.
         return if (legal.contains(Pass)) Pass else best
     }
 
-    private fun chooseDiscard(state: EuchreState, legal: List<EuchreMove>): EuchreMove {
+    private fun chooseDiscard(
+        state: EuchreState,
+        legal: List<EuchreMove>,
+        profile: AiProfile,
+    ): EuchreMove {
         val trump = requireNotNull(state.trump)
         val discards = legal.filterIsInstance<Discard>()
         // Prefer to void a side suit entirely; otherwise throw the lowest card.
         val hand = state.hands[state.dealer]
         val suitCounts = hand.groupingBy { effectiveSuit(it, trump) }.eachCount()
-        return discards.minByOrNull { discard ->
+        fun keepScore(discard: Discard): Int {
             val card = discard.card
             val suit = effectiveSuit(card, trump)
             val trumpPenalty = if (suit == trump) 1000 else 0
             val singletonBonus = if (suitCounts[suit] == 1 && card.rank != Rank.ACE) -20 else 0
-            trumpPenalty + singletonBonus + card.rank.order
-        } ?: discards.first()
+            return trumpPenalty + singletonBonus + card.rank.order
+        }
+        return when (profile.level) {
+            AiLevel.HARD -> discards
+                .sortedWith(
+                    compareByDescending<Discard> { handValue(hand - it.card, trump) }
+                        .thenBy { keepScore(it) },
+                )
+                .first()
+            AiLevel.EASY -> profile.pick(discards.sortedBy { keepScore(it) })
+            AiLevel.MEDIUM -> discards.minByOrNull { keepScore(it) } ?: discards.first()
+        }
     }
 
     // -----------------------------------------------------------------------
@@ -144,12 +234,40 @@ class EuchreAi(private val difficulty: Difficulty = Difficulty.NORMAL) :
         state: EuchreState,
         seat: Int,
         legal: List<EuchreMove>,
+        profile: AiProfile,
+        seen: Set<Card>,
     ): EuchreMove {
         val trump = requireNotNull(state.trump)
         val cards = legal.filterIsInstance<PlayCard>().map { it.card }
         if (cards.size == 1) return PlayCard(cards.first())
 
-        if (state.trick.isEmpty()) return PlayCard(chooseLead(cards, trump))
+        val maker = state.maker
+        val defending = maker != null && teamOf(maker) != teamOf(seat)
+        val makerSide = maker != null && teamOf(maker) == teamOf(seat)
+        // A spoiler on the defence leads trump to cut the maker's trump down.
+        val spiteful = defending && profile.style.spite >= 0.5
+
+        val best = if (profile.level == AiLevel.HARD) {
+            hardPlay(state, seat, cards, trump, seen, makerSide, spiteful)
+        } else {
+            standardPlay(state, seat, cards, trump, spiteful, profile)
+        }
+        if (profile.level != AiLevel.EASY) return PlayCard(best)
+
+        // Easy sometimes burns a high card it should have kept.
+        val ranked = listOf(best) + (cards - best).sortedByDescending { trumpStrength(it, trump) }
+        return PlayCard(profile.pick(ranked))
+    }
+
+    private fun standardPlay(
+        state: EuchreState,
+        seat: Int,
+        cards: List<Card>,
+        trump: Suit,
+        spiteful: Boolean,
+        profile: AiProfile,
+    ): Card {
+        if (state.trick.isEmpty()) return chooseLead(cards, trump, spiteful)
 
         val ledSuit = effectiveSuit(state.trick.first().card, trump)
         val bestSoFar = state.trick.maxBy { trickStrength(it.card, trump, ledSuit) }
@@ -157,22 +275,120 @@ class EuchreAi(private val difficulty: Difficulty = Difficulty.NORMAL) :
         val lastToPlay = state.trick.size == state.activeSeatCount - 1
 
         // Partner already has it and we are last: never waste a good card.
-        if (partnerWinning && lastToPlay) return PlayCard(lowest(cards, trump, ledSuit))
+        // (Easy sometimes forgets and overtakes anyway.)
+        if (partnerWinning && lastToPlay && !profile.slips()) {
+            return lowest(cards, trump, ledSuit)
+        }
 
         val bestStrength = trickStrength(bestSoFar.card, trump, ledSuit)
         val winners = cards.filter { trickStrength(it, trump, ledSuit) > bestStrength }
         return when {
             // Take it as cheaply as we can.
-            winners.isNotEmpty() && (!partnerWinning || !lastToPlay) ->
-                PlayCard(winners.minBy { trickStrength(it, trump, ledSuit) })
+            winners.isNotEmpty() && (!partnerWinning || !lastToPlay || profile.level == AiLevel.EASY) ->
+                winners.minBy { trickStrength(it, trump, ledSuit) }
 
-            else -> PlayCard(lowest(cards, trump, ledSuit))
+            else -> lowest(cards, trump, ledSuit)
         }
     }
 
-    private fun chooseLead(cards: List<Card>, trump: Suit): Card {
+    /**
+     * The strong player's choice. It remembers which cards have gone, so it
+     * knows when a card is the best one left, and it lets a partner who is
+     * already safe take the trick.
+     */
+    private fun hardPlay(
+        state: EuchreState,
+        seat: Int,
+        cards: List<Card>,
+        trump: Suit,
+        seen: Set<Card>,
+        makerSide: Boolean,
+        spiteful: Boolean,
+    ): Card {
+        val hand = state.hands[seat]
+        // Cards that could still be in somebody else's hand.
+        val unseen = Decks.euchre(state.options.deckSize).filter { it !in seen && it !in hand }
+        val unseenTrump = unseen.count { isTrumpCard(it, trump) }
+
+        /** No unseen card of its suit beats it; trump is ignored for a side-suit card. */
+        fun isBoss(card: Card): Boolean {
+            val led = effectiveSuit(card, trump)
+            val mine = trickStrength(card, trump, led)
+            val cardIsTrump = isTrumpCard(card, trump)
+            return unseen.none { other ->
+                (cardIsTrump || !isTrumpCard(other, trump)) && trickStrength(other, trump, led) > mine
+            }
+        }
+
+        if (state.trick.isEmpty()) {
+            val myTrump = cards.filter { isTrumpCard(it, trump) }
+            val off = cards.filter { !isTrumpCard(it, trump) }
+            val bossTrump = myTrump.filter { isBoss(it) }.maxByOrNull { trumpStrength(it, trump) }
+            if (unseenTrump > 0 && bossTrump != null && (makerSide || myTrump.size >= 2)) return bossTrump
+            if (unseenTrump > 0 && makerSide && myTrump.size >= 3) {
+                return myTrump.maxBy { trumpStrength(it, trump) }
+            }
+            if (unseenTrump > 0 && spiteful && myTrump.size >= 2) {
+                return myTrump.maxBy { trumpStrength(it, trump) }
+            }
+            val bossOff = off.filter { isBoss(it) }.maxByOrNull { it.rank.order }
+            if (bossOff != null) return bossOff
+            if (bossTrump != null) return bossTrump
+            if (off.isEmpty()) return cards.maxBy { trumpStrength(it, trump) }
+            if (makerSide) return chooseLead(cards, trump, false)
+            // On the defence with nothing sure: lead low from the shortest suit,
+            // which keeps the aces and sets up a ruff.
+            val counts = hand.groupingBy { effectiveSuit(it, trump) }.eachCount()
+            return off.minWith(
+                compareBy<Card>({ counts[effectiveSuit(it, trump)] ?: 0 }, { it.rank.order }),
+            )
+        }
+
+        val ledSuit = effectiveSuit(state.trick.first().card, trump)
+        val bestSoFar = state.trick.maxBy { trickStrength(it.card, trump, ledSuit) }
+        val partnerWinning = partnerOf(bestSoFar.seat) == seat
+        val remaining = state.activeSeatCount - state.trick.size - 1
+        val bestStrength = trickStrength(bestSoFar.card, trump, ledSuit)
+        val winners = cards.filter { trickStrength(it, trump, ledSuit) > bestStrength }
+
+        fun safe(card: Card): Boolean =
+            remaining == 0 ||
+                unseen.none { trickStrength(it, trump, ledSuit) > trickStrength(card, trump, ledSuit) }
+
+        fun throwAway(): Card {
+            // A card that neither follows nor trumps costs nothing; shed the
+            // lowest one that is not a sure winner later.
+            val junk = cards.filter { trickStrength(it, trump, ledSuit) == 0 }
+            if (junk.isNotEmpty()) {
+                return junk.minBy { it.rank.order + if (isBoss(it)) 100 else 0 }
+            }
+            return lowest(cards, trump, ledSuit)
+        }
+
+        if (partnerWinning) {
+            val partnerSecure = remaining == 0 ||
+                unseen.none { trickStrength(it, trump, ledSuit) > bestStrength }
+            if (partnerSecure) return throwAway()
+            // Partner may yet be beaten: back them with a side-suit card, but do
+            // not spend trump on top of their lead.
+            val backing = winners.filter { !isTrumpCard(it, trump) }
+                .minByOrNull { trickStrength(it, trump, ledSuit) }
+            return backing ?: throwAway()
+        }
+        if (winners.isNotEmpty()) {
+            val sure = winners.filter { safe(it) }
+            return (sure.ifEmpty { winners }).minBy { trickStrength(it, trump, ledSuit) }
+        }
+        return throwAway()
+    }
+
+    private fun chooseLead(cards: List<Card>, trump: Suit, spiteTrump: Boolean): Card {
         // Right bower up front pulls trump and protects the left.
         cards.firstOrNull { isRightBower(it, trump) }?.let { return it }
+        if (spiteTrump) {
+            val trumps = cards.filter { isTrumpCard(it, trump) }
+            if (trumps.size >= 2) return trumps.maxBy { trumpStrength(it, trump) }
+        }
         // Off-suit aces are most likely to survive early.
         cards.filter { !isTrumpCard(it, trump) && it.rank == Rank.ACE }
             .maxByOrNull { it.rank.order }

app/src/main/java/org/prolibertate/games/game/golf/GolfAi.kt

@@ -1,49 +1,78 @@
 package org.prolibertate.games.game.golf
 
+import org.prolibertate.games.game.cards.Card
+import org.prolibertate.games.game.cards.Rank
+import org.prolibertate.games.game.cards.Suit
+import org.prolibertate.games.game.engine.AiLevel
+import org.prolibertate.games.game.engine.AiProfile
+import org.prolibertate.games.game.engine.AiProfiles
 import org.prolibertate.games.game.engine.GameAi
 
 /**
- * A heuristic Golf opponent.
+ * A Golf opponent whose strength and temperament come from the seat's profile.
  *
- * It takes a card off the discard pile when it is cheap or completes a column,
- * replaces its worst known card, and turns cards over when it has nothing
- * better to do. It never peeks at a face-down card — including its own, which
- * it genuinely does not know.
+ * MEDIUM (the default) takes a card off the discard pile when it is cheap or
+ * completes a column, replaces its worst known card, and turns cards over when
+ * it has nothing better to do. It never peeks at a face-down card — including
+ * its own, which it genuinely does not know.
+ *
+ * EASY is pickier about the discard pile, closes the hole from a poor position
+ * and sometimes makes a worse play than it saw. HARD keeps count of every card
+ * it has seen (turned-over grids and the discard pile), values its unknown
+ * cards at what is still unseen, and chooses each draw and placement by how
+ * much it lowers its expected score, including the chance of completing a
+ * column and whether closing the hole would leave it ahead.
  */
-class GolfAi(private val difficulty: Difficulty = Difficulty.NORMAL) :
+class GolfAi(private val profiles: AiProfiles = AiProfiles.DEFAULT) :
     GameAi<GolfState, GolfMove> {
 
-    enum class Difficulty(
+    /** The tuning the standard plan runs on. */
+    private class Params(
         /** Take a discard worth this or less rather than gambling on the stock. */
         val discardAppetite: Int,
         /** Only close the hole out when the visible score is at or under this. */
         val closeOutBelow: Int,
-    ) {
-        EASY(discardAppetite = 2, closeOutBelow = 30),
-        NORMAL(discardAppetite = 5, closeOutBelow = 16),
-        CAUTIOUS(discardAppetite = 7, closeOutBelow = 12),
-    }
+    )
 
     override fun chooseMove(state: GolfState, seat: Int, legal: List<GolfMove>): GolfMove {
         require(legal.isNotEmpty()) { "No legal move for seat $seat" }
-        return when (state.phase) {
-            GolfPhase.SETUP -> chooseReveal(state, seat, legal)
-            GolfPhase.DRAW -> chooseDraw(state, seat, legal)
-            GolfPhase.PLACE -> choosePlace(state, seat, legal)
+        val profile = profiles.of(seat)
+        val move = when (state.phase) {
+            GolfPhase.SETUP -> chooseReveal(state, seat, legal, profile)
+            GolfPhase.DRAW -> chooseDraw(state, seat, legal, profile)
+            GolfPhase.PLACE -> choosePlace(state, seat, legal, profile)
             else -> legal.first()
         }
+        return if (move in legal) move else legal.first()
     }
 
+    private fun paramsFor(level: AiLevel): Params = when (level) {
+        AiLevel.EASY -> EASY
+        else -> NORMAL
+    }
+
+    // -----------------------------------------------------------------------
+    // Setup
+    // -----------------------------------------------------------------------
+
     /**
      * Opening reveals are spread across columns. Two cards in the same column
      * tell you whether that column can be cancelled but nothing about the rest
      * of the board; one in each column leaves more of the grid legible.
      */
-    private fun chooseReveal(state: GolfState, seat: Int, legal: List<GolfMove>): GolfMove {
+    private fun chooseReveal(
+        state: GolfState,
+        seat: Int,
+        legal: List<GolfMove>,
+        profile: AiProfile,
+    ): GolfMove {
         val reveals = legal.filterIsInstance<RevealCard>()
         if (reveals.isEmpty()) return legal.first()
         val options = state.options
 
+        // A distracted player turns over whatever is nearest.
+        if (profile.slips()) return reveals[profile.random.nextInt(reveals.size)]
+
         val untouchedColumn = reveals.firstOrNull { move ->
             val column = move.index % options.cols
             (0 until options.rows).none { row ->
@@ -53,17 +82,61 @@ class GolfAi(private val difficulty: Difficulty = Difficulty.NORMAL) :
         return untouchedColumn ?: reveals.first()
     }
 
-    private fun chooseDraw(state: GolfState, seat: Int, legal: List<GolfMove>): GolfMove {
+    // -----------------------------------------------------------------------
+    // Drawing
+    // -----------------------------------------------------------------------
+
+    private fun chooseDraw(
+        state: GolfState,
+        seat: Int,
+        legal: List<GolfMove>,
+        profile: AiProfile,
+    ): GolfMove {
+        if (profile.level == AiLevel.HARD) return hardDraw(state, seat, legal, profile)
+
+        val params = paramsFor(profile.level)
         val top = state.discard.lastOrNull()
+        var take = false
         if (top != null && legal.contains(DrawFromDiscard)) {
-            val worthTaking = golfValue(top) <= difficulty.discardAppetite ||
+            take = golfValue(top) <= params.discardAppetite ||
                 completesColumn(state, seat, top) != null
-            if (worthTaking) return DrawFromDiscard
         }
+        // Easy sometimes flips its own decision.
+        if (profile.slips() && legal.contains(DrawFromDiscard) && legal.contains(DrawFromStock)) take = !take
+        if (take && legal.contains(DrawFromDiscard)) return DrawFromDiscard
         return if (legal.contains(DrawFromStock)) DrawFromStock else legal.first()
     }
 
-    private fun choosePlace(state: GolfState, seat: Int, legal: List<GolfMove>): GolfMove {
+    // -----------------------------------------------------------------------
+    // Placing
+    // -----------------------------------------------------------------------
+
+    private fun choosePlace(
+        state: GolfState,
+        seat: Int,
+        legal: List<GolfMove>,
+        profile: AiProfile,
+    ): GolfMove {
+        if (profile.level == AiLevel.HARD) return hardPlace(state, seat, legal, profile)
+
+        val best = standardPlace(state, seat, legal, paramsFor(profile.level))
+        if (profile.level != AiLevel.EASY || !profile.slips()) return best
+
+        // A lapse: turn something over or cover a face-down card instead.
+        val alternatives = buildList<GolfMove> {
+            addAll(legal.filterIsInstance<DiscardAndFlip>())
+            addAll(legal.filterIsInstance<ReplaceCard>().filter { !state.revealed[seat][it.index] })
+        }.filter { it != best }
+        if (alternatives.isEmpty()) return best
+        return alternatives[profile.random.nextInt(alternatives.size)]
+    }
+
+    private fun standardPlace(
+        state: GolfState,
+        seat: Int,
+        legal: List<GolfMove>,
+        params: Params,
+    ): GolfMove {
         val drawn = state.drawn ?: return legal.first()
         val replacements = legal.filterIsInstance<ReplaceCard>()
         val flips = legal.filterIsInstance<DiscardAndFlip>()
@@ -90,7 +163,7 @@ class GolfAi(private val difficulty: Difficulty = Difficulty.NORMAL) :
             val showing = state.grids[seat].indices
                 .filter { state.revealed[seat][it] }
                 .sumOf { golfValue(state.grids[seat][it]) }
-            if (showing > difficulty.closeOutBelow) return DiscardOnly
+            if (showing > params.closeOutBelow) return DiscardOnly
         }
 
         // Nothing worth swapping: throw it and turn something over instead,
@@ -106,7 +179,7 @@ class GolfAi(private val difficulty: Difficulty = Difficulty.NORMAL) :
     private fun completesColumn(
         state: GolfState,
         seat: Int,
-        card: org.prolibertate.games.game.cards.Card,
+        card: Card,
     ): Int? {
         val options = state.options
         for (col in 0 until options.cols) {
@@ -122,4 +195,229 @@ class GolfAi(private val difficulty: Difficulty = Difficulty.NORMAL) :
         }
         return null
     }
+
+    // -----------------------------------------------------------------------
+    // Hard
+    // -----------------------------------------------------------------------
+
+    /**
+     * What this seat knows about the hole: the cards in every turned-over cell,
+     * the discard pile and (on its own turn) the card in its hand. Everything
+     * else — face-down cells and the stock — is valued at the average of the
+     * cards not yet seen.
+     */
+    private class Board(private val state: GolfState, seat: Int) {
+        val options = state.options
+        private val counts = HashMap<Rank, Int>()
+        private val unseenTotal: Int
+        val unknownValue: Double
+        private val lines: List<List<Int>>
+
+        init {
+            val copies = if (options.playerCount * options.gridSize > 24) 2 else 1
+            Rank.standard.forEach { counts[it] = 4 * copies }
+            fun see(card: Card) {
+                counts[card.rank] = maxOf(0, (counts[card.rank] ?: 0) - 1)
+            }
+            state.grids.forEachIndexed { player, grid ->
+                grid.forEachIndexed { index, card -> if (state.revealed[player][index]) see(card) }
+            }
+            state.discard.forEach { see(it) }
+            if (seat == state.turn) state.drawn?.let { see(it) }
+
+            unseenTotal = counts.values.sum()
+            unknownValue = if (unseenTotal == 0) {
+                5.0
+            } else {
+                counts.entries.sumOf { (rank, n) -> n * valueOf(rank).toDouble() } / unseenTotal
+            }
+
+            val columns = (0 until options.cols).map { col -> (0 until options.rows).map { it * options.cols + col } }
+            val rows = if (options.rows == 3) {
+                (0 until options.rows).map { row -> (0 until options.cols).map { row * options.cols + it } }
+            } else {
+                emptyList()
+            }
+            lines = columns + rows
+        }
+
+        fun valueOf(rank: Rank): Int = golfValue(Card(rank, Suit.SPADES))
+
+        private fun chanceOf(rank: Rank): Double =
+            if (unseenTotal == 0) 0.0 else (counts[rank] ?: 0).toDouble() / unseenTotal
+
+        /** A seat's cells as far as this seat can see them; null is a face-down card. */
+        fun cellsOf(player: Int): List<Card?> =
+            state.grids[player].mapIndexed { index, card -> if (state.revealed[player][index]) card else null }
+
+        /** Expected score of a grid, counting the chance that an unknown cell completes a line. */
+        fun expected(cells: List<Card?>): Double {
+            val cancelled = BooleanArray(cells.size)
+            for (line in lines) {
+                val line0 = line.map { cells[it] }
+                if (line0.all { it != null } && line0.map { it!!.rank }.distinct().size == 1) {
+                    line.forEach { cancelled[it] = true }
+                }
+            }
+            var total = 0.0
+            for (index in cells.indices) {
+                if (cancelled[index]) continue
+                val card = cells[index]
+                total += if (card != null) golfValue(card).toDouble() else unknownValue
+            }
+            for (line in lines) {
+                if (line.any { cancelled[it] }) continue
+                val unknown = line.filter { cells[it] == null }
+                if (unknown.size != 1) continue
+                val known = line.mapNotNull { cells[it] }
+                if (known.isEmpty() || known.map { it.rank }.distinct().size != 1) continue
+                val rank = known.first().rank
+                total -= chanceOf(rank) * (known.sumOf { golfValue(it) } + valueOf(rank))
+            }
+            return total
+        }
+
+        /** Unseen ranks and how many of each remain, for averaging over a stock draw. */
+        fun unseenRanks(): List<Pair<Rank, Int>> = counts.entries.filter { it.value > 0 }.map { it.key to it.value }
+
+        /** How likely turning over [index] is to finish a line that already shows one rank. */
+        fun matchHope(cells: List<Card?>, index: Int): Double {
+            var best = 0.0
+            for (line in lines) {
+                if (index !in line) continue
+                val others = line.filter { it != index }
+                val known = others.mapNotNull { cells[it] }
+                if (known.size != others.size || known.isEmpty()) continue
+                if (known.map { it.rank }.distinct().size != 1) continue
+                val rank = known.first().rank
+                best = maxOf(best, chanceOf(rank) * (known.sumOf { golfValue(it) } + valueOf(rank)))
+            }
+            return best
+        }
+    }
+
+    private fun effectiveBoldness(state: GolfState, seat: Int, profile: AiProfile): Double {
+        // Well behind late in the match: take more chances.
+        val holesLeft = state.options.holes - state.hole - 1
+        val best = (0 until state.options.playerCount).filter { it != seat }.minOf { state.scores[it] }
+        val behind = state.scores[seat] - best
+        return profile.style.boldness + if (holesLeft <= 2 && behind > 8) 0.3 else 0.0
+    }
+
+    /** Scores one way of using the card in hand: lower grid score, more information, less risk. */
+    private class Planner(
+        val state: GolfState,
+        val seat: Int,
+        val board: Board,
+        val boldness: Double,
+        val spite: Double,
+    ) {
+        private val cells = board.cellsOf(seat)
+        private val before = board.expected(cells)
+        private val hidden = cells.count { it == null }
+        private val finalTurn = state.closedBy != null
+        private val rivalBest: Double = (0 until state.options.playerCount)
+            .filter { it != seat }
+            .minOfOrNull { board.expected(board.cellsOf(it)) } ?: before
+
+        private fun closePenalty(after: Double): Double {
+            if (finalTurn) return 0.0
+            val margin = 2.0 - 2.0 * boldness
+            return maxOf(0.0, after - (rivalBest - margin)) * 0.8
+        }
+
+        private fun handoff(drawn: Card): Double =
+            maxOf(0.0, 3.0 - golfValue(drawn)) * 0.15 * (1.0 + spite)
+
+        private fun flipBonus(index: Int): Double =
+            if (finalTurn || hidden <= 1) 0.0 else 0.35 + 0.5 * board.matchHope(cells, index)
+
+        /** Utility of [move] with [drawn] in hand; higher is better. */
+        fun utility(move: GolfMove, drawn: Card): Double = when (move) {
+            is ReplaceCard -> {
+                val after = cells.toMutableList().also { it[move.index] = drawn }
+                val closes = hidden == 1 && cells[move.index] == null
+                val afterScore = board.expected(after)
+                before - afterScore - if (closes) closePenalty(afterScore) else 0.0
+            }
+
+            is DiscardAndFlip -> {
+                val closes = hidden == 1
+                flipBonus(move.index) - handoff(drawn) - if (closes) closePenalty(before) else 0.0
+            }
+
+            is DiscardOnly -> -handoff(drawn)
+            else -> Double.NEGATIVE_INFINITY
+        }
+
+        /** The moves open to a card in hand, standing in for the legal list during look-ahead. */
+        fun candidates(fromDiscard: Boolean, putt: Boolean): List<GolfMove> = buildList {
+            for (index in cells.indices) add(ReplaceCard(index))
+            if (!fromDiscard) {
+                for (index in cells.indices) if (cells[index] == null) add(DiscardAndFlip(index))
+                if (putt && hidden == 1) add(DiscardOnly)
+            }
+        }
+    }
+
+    private fun planner(state: GolfState, seat: Int, profile: AiProfile): Planner {
+        val board = Board(state, seat)
+        return Planner(state, seat, board, effectiveBoldness(state, seat, profile), profile.style.spite)
+    }
+
+    private fun hardDraw(
+        state: GolfState,
+        seat: Int,
+        legal: List<GolfMove>,
+        profile: AiProfile,
+    ): GolfMove {
+        val top = state.discard.lastOrNull()
+        val canStock = legal.contains(DrawFromStock)
+        val canDiscard = legal.contains(DrawFromDiscard) && top != null
+        if (!canDiscard) return if (canStock) DrawFromStock else legal.first()
+        if (!canStock) return DrawFromDiscard
+
+        val plan = planner(state, seat, profile)
+        val putt = state.options.lineUpFinalPutt
+
+        // The discard has to be used, so it is only as good as its best replacement.
+        val takeUtility = plan.candidates(fromDiscard = true, putt = putt)
+            .maxOf { plan.utility(it, top!!) } +
+            profile.style.spite * 0.3 * maxOf(0, 4 - golfValue(top!!))
+
+        // The stock is a gamble on the average of what is left, but can be thrown back.
+        val ranks = plan.board.unseenRanks()
+        val total = ranks.sumOf { it.second }
+        val stockUtility = if (total == 0) {
+            Double.NEGATIVE_INFINITY
+        } else {
+            val moves = plan.candidates(fromDiscard = false, putt = putt)
+            ranks.sumOf { (rank, n) ->
+                val sample = Card(rank, Suit.SPADES)
+                n * moves.maxOf { plan.utility(it, sample) }
+            } / total
+        }
+
+        // A bold seat wants a clear edge before it passes up the unknown card.
+        val take = takeUtility - plan.boldness * 0.4 > stockUtility
+        return if (take) DrawFromDiscard else DrawFromStock
+    }
+
+    private fun hardPlace(
+        state: GolfState,
+        seat: Int,
+        legal: List<GolfMove>,
+        profile: AiProfile,
+    ): GolfMove {
+        val drawn = state.drawn ?: return legal.first()
+        val plan = planner(state, seat, profile)
+        val options = legal.filter { it is ReplaceCard || it is DiscardAndFlip || it is DiscardOnly }
+        if (options.isEmpty()) return legal.first()
+        return options.maxBy { plan.utility(it, drawn) }
+    }
+
+    private companion object {
+        private val EASY = Params(discardAppetite = 2, closeOutBelow = 30)
+        private val NORMAL = Params(discardAppetite = 5, closeOutBelow = 16)
+    }
 }

app/src/main/java/org/prolibertate/games/game/hearts/HeartsAi.kt

@@ -3,35 +3,98 @@ package org.prolibertate.games.game.hearts
 import org.prolibertate.games.game.cards.Card
 import org.prolibertate.games.game.cards.Rank
 import org.prolibertate.games.game.cards.Suit
+import org.prolibertate.games.game.engine.AiLevel
+import org.prolibertate.games.game.engine.AiProfile
+import org.prolibertate.games.game.engine.AiProfiles
 import org.prolibertate.games.game.engine.GameAi
 
 /**
- * A cautious Hearts player.
+ * A Hearts player whose strength and temperament come from the seat's profile.
  *
- * It plays to avoid points rather than to shoot the moon: it sheds the queen of
- * spades and the guards above her at the first opportunity, ducks under whoever
- * is winning a trick when it can, and takes a trick as cheaply as possible when
- * it cannot get out of the way. That is enough to make it an opponent worth
- * beating without pretending to read the table.
+ * MEDIUM (the default) avoids points rather than shooting the moon: it sheds
+ * the queen of spades and the guards above her at the first opportunity, ducks
+ * under whoever is winning a trick when it can, and takes a trick as cheaply as
+ * possible when it cannot get out of the way.
+ *
+ * EASY plays the same plan but sometimes settles for a worse card in each
+ * decision. HARD counts the penalty cards and spades that have been taken,
+ * leads by risk, sheds by what is still dangerous, shoots the moon when its
+ * hand and the table allow it and tries to break a moon somebody else is on.
+ * It only uses its own hand and what the table has shown.
  */
-object HeartsAi : GameAi<HeartsState, HeartsMove> {
+class HeartsAi(private val profiles: AiProfiles = AiProfiles.DEFAULT) : GameAi<HeartsState, HeartsMove> {
 
     override fun chooseMove(state: HeartsState, seat: Int, legal: List<HeartsMove>): HeartsMove {
         require(legal.isNotEmpty()) { "No legal move for seat $seat" }
-        return when (state.phase) {
-            HeartsPhase.PASSING -> choosePass(state, seat, legal)
-            else -> choosePlay(state, seat, legal)
+        val profile = profiles.of(seat)
+        val move = when (state.phase) {
+            HeartsPhase.PASSING -> choosePass(state, seat, legal, profile)
+            else -> choosePlay(state, seat, legal, profile)
         }
+        return if (move in legal) move else legal.first()
     }
 
-    private fun choosePass(state: HeartsState, seat: Int, legal: List<HeartsMove>): HeartsMove {
+    // -----------------------------------------------------------------------
+    // Passing
+    // -----------------------------------------------------------------------
+
+    private fun choosePass(
+        state: HeartsState,
+        seat: Int,
+        legal: List<HeartsMove>,
+        profile: AiProfile,
+    ): HeartsMove {
         val hand = state.hands[seat]
-        val wanted = hand.sortedByDescending { passDanger(it, hand) }.take(PASS_SIZE).toSet()
+        val wanted: Set<Card> = when (profile.level) {
+            AiLevel.MEDIUM -> hand.sortedByDescending { passDanger(it, hand) }.take(PASS_SIZE).toSet()
+            AiLevel.EASY -> easyPass(hand, profile)
+            AiLevel.HARD -> hardPass(state, hand, profile)
+        }
         // Prefer the exact bundle the heuristic asked for, but fall back rather
         // than fail: the caller's list is what the host will validate against.
         return legal.firstOrNull { it is PassCards && it.cards.toSet() == wanted } ?: legal.first()
     }
 
+    private fun easyPass(hand: List<Card>, profile: AiProfile): Set<Card> {
+        val ranked = hand.sortedByDescending { passDanger(it, hand) }
+        val chosen = ranked.take(PASS_SIZE).toMutableList()
+        if (profile.slips()) {
+            // Keeps one of the cards it should have sent.
+            val spare = ranked.drop(PASS_SIZE).take(4)
+            if (spare.isNotEmpty()) {
+                chosen[profile.random.nextInt(chosen.size)] = spare[profile.random.nextInt(spare.size)]
+            }
+        }
+        return chosen.toSet()
+    }
+
+    private fun hardPass(state: HeartsState, hand: List<Card>, profile: AiProfile): Set<Card> {
+        if (state.options.allowShootTheMoon && moonHand(hand, profile)) {
+            // Keep every high card and heart, send the three smallest.
+            val junk = hand.filter { !(it.suit == Suit.HEARTS && it.rank.order >= 10) }
+                .sortedBy { it.rank.order }
+            if (junk.size >= PASS_SIZE) return junk.take(PASS_SIZE).toSet()
+        }
+        return hand.sortedByDescending { passDanger(it, hand) + shortSuitBonus(it, hand) }
+            .take(PASS_SIZE).toSet()
+    }
+
+    /** Sending away the last cards of a short suit makes a void, which is worth a lot when discarding. */
+    private fun shortSuitBonus(card: Card, hand: List<Card>): Int {
+        if (card.suit == Suit.HEARTS || card.suit == Suit.SPADES) return 0
+        val length = hand.count { it.suit == card.suit }
+        return if (length > 3) 0 else (4 - length) * 8
+    }
+
+    /** A hand worth trying to take all twenty-six with: lots of high cards and a heart suit to run. */
+    private fun moonHand(hand: List<Card>, profile: AiProfile): Boolean {
+        val hearts = hand.count { it.suit == Suit.HEARTS }
+        if (hearts < 4) return false
+        val strength = hand.count { it.rank.order >= Rank.QUEEN.order } +
+            hand.count { it.suit == Suit.HEARTS && it.rank.order >= 9 }
+        return strength >= profile.bolder(8.0, -2.0)
+    }
+
     /**
      * How much a card wants to be somebody else's problem.
      *
@@ -52,27 +115,41 @@ object HeartsAi : GameAi<HeartsState, HeartsMove> {
         }
     }
 
-    private fun choosePlay(state: HeartsState, seat: Int, legal: List<HeartsMove>): HeartsMove {
+    // -----------------------------------------------------------------------
+    // Playing
+    // -----------------------------------------------------------------------
+
+    private fun choosePlay(
+        state: HeartsState,
+        seat: Int,
+        legal: List<HeartsMove>,
+        profile: AiProfile,
+    ): HeartsMove {
         val cards = legal.filterIsInstance<PlayCard>().map { it.card }
         if (cards.isEmpty()) return legal.first()
-        val chosen = when {
-            state.trick.isEmpty() -> lead(cards)
-            else -> follow(state, cards)
+        val chosen = when (profile.level) {
+            AiLevel.MEDIUM -> standardRanking(state, cards).first()
+            AiLevel.EASY -> profile.pick(standardRanking(state, cards))
+            AiLevel.HARD -> hardPlay(state, seat, cards, profile)
         }
-        return PlayCard(chosen)
+        return PlayCard(if (chosen in cards) chosen else cards.first())
     }
 
+    /** The standard plan's preferences, best first. */
+    private fun standardRanking(state: HeartsState, cards: List<Card>): List<Card> =
+        if (state.trick.isEmpty()) rankedLead(cards) else rankedFollow(state, cards)
+
     /**
      * Leads low, and keeps off spades while the queen is still unaccounted for —
      * leading a spade under her is how a seat ends up holding her.
      */
-    private fun lead(cards: List<Card>): Card {
-        val offSpades = cards.filter { it.suit != Suit.SPADES }
-        val pool = if (offSpades.isNotEmpty()) offSpades else cards
-        return pool.minBy { it.rank.order }
+    private fun rankedLead(cards: List<Card>): List<Card> {
+        val offSpades = cards.filter { it.suit != Suit.SPADES }.sortedBy { it.rank.order }
+        val spades = cards.filter { it.suit == Suit.SPADES }.sortedBy { it.rank.order }
+        return offSpades + spades
     }
 
-    private fun follow(state: HeartsState, cards: List<Card>): Card {
+    private fun rankedFollow(state: HeartsState, cards: List<Card>): List<Card> {
         val led = state.trick.first().card.suit
         val best = state.trick.maxOf { trickStrength(it.card, led) }
         val pot = pointsIn(state.trick.map { it.card })
@@ -82,27 +159,189 @@ object HeartsAi : GameAi<HeartsState, HeartsMove> {
         if (ducking.isNotEmpty()) {
             // Safe under the current winner, so shed the most expensive card
             // that still loses.
-            return ducking.maxBy { it.rank.order + pointsOf(it) * 2 }
+            val rest = (cards - ducking.toSet()).sortedBy { it.rank.order }
+            return ducking.sortedByDescending { it.rank.order + pointsOf(it) * 2 } + rest
         }
 
-        val void = cards.none { it.suit == led }
-        if (void) return discard(cards)
-
         // Every card left would take the trick. Playing last with nothing in the
         // pot means it costs nothing, so there is no reason to waste a high card
         // on it; otherwise take it as cheaply as possible.
-        return if (last && pot == 0) cards.maxBy { it.rank.order } else cards.minBy { it.rank.order }
+        return if (last && pot == 0) {
+            cards.sortedByDescending { it.rank.order }
+        } else {
+            cards.sortedBy { it.rank.order }
+        }
     }
 
-    /** Void in the led suit and free to throw anything, so throw the worst of it. */
-    private fun discard(cards: List<Card>): Card {
-        cards.firstOrNull { it == QUEEN_OF_SPADES }?.let { return it }
-        cards.filter { it.suit == Suit.SPADES && it.rank.order > Rank.QUEEN.order }
-            .maxByOrNull { it.rank.order }
-            ?.let { return it }
-        cards.filter { it.suit == Suit.HEARTS }
-            .maxByOrNull { it.rank.order }
-            ?.let { return it }
-        return cards.maxBy { it.rank.order }
+    // -----------------------------------------------------------------------
+    // Hard play
+    // -----------------------------------------------------------------------
+
+    /** What this seat can legitimately know: its hand, and every card taken or on the table. */
+    private class Memory(state: HeartsState, seat: Int) {
+        val hand: List<Card> = state.hands[seat]
+        val unseen: List<Card>
+
+        init {
+            val seen = HashSet<Card>()
+            state.taken.forEach { seen.addAll(it) }
+            state.trick.forEach { seen.add(it.card) }
+            seen.addAll(hand)
+            unseen = FULL_DECK.filter { it !in seen }
+        }
+
+        val queenUnseen: Boolean get() = QUEEN_OF_SPADES in unseen
+
+        fun unseenIn(suit: Suit): Int = unseen.count { it.suit == suit }
+
+        fun unseenHigher(card: Card): Int =
+            unseen.count { it.suit == card.suit && it.rank.order > card.rank.order }
+    }
+
+    private fun hardPlay(state: HeartsState, seat: Int, cards: List<Card>, profile: AiProfile): Card {
+        val mem = Memory(state, seat)
+        if (isShooting(state, seat, mem, profile)) return shootPlay(state, cards, mem)
+        return if (state.trick.isEmpty()) {
+            hardLead(cards, mem, profile)
+        } else {
+            hardFollow(state, seat, cards, mem, profile)
+        }
+    }
+
+    /** Holding every point so far, with a hand that can keep winning. */
+    private fun isShooting(state: HeartsState, seat: Int, mem: Memory, profile: AiProfile): Boolean {
+        if (!state.options.allowShootTheMoon) return false
+        val all = pointsIn(state.taken.flatten())
+        val mine = pointsIn(state.taken[seat])
+        if (mine != all) return false
+        if (mine == 0 && !moonHand(mem.hand, profile)) return false
+        if (mem.hand.isEmpty()) return false
+        val masters = mem.hand.count { mem.unseenHigher(it) == 0 }
+        return masters.toDouble() / mem.hand.size >= profile.bolder(0.6, -0.15)
+    }
+
+    private fun shootPlay(state: HeartsState, cards: List<Card>, mem: Memory): Card {
+        if (state.trick.isEmpty()) {
+            val masters = cards.filter { mem.unseenHigher(it) == 0 }
+            if (masters.isNotEmpty()) {
+                return masters.sortedWith(
+                    compareBy<Card> { it.suit == Suit.HEARTS }.thenByDescending { it.rank.order },
+                ).first()
+            }
+            return cards.maxBy { it.rank.order }
+        }
+        val led = state.trick.first().card.suit
+        val best = state.trick.maxOf { trickStrength(it.card, led) }
+        val remaining = state.options.playerCount - state.trick.size - 1
+        val winning = cards.filter { trickStrength(it, led) > best }
+        if (winning.isNotEmpty()) {
+            if (remaining == 0) return winning.minBy { it.rank.order }
+            return winning.filter { mem.unseenHigher(it) == 0 }.minByOrNull { it.rank.order }
+                ?: winning.maxBy { it.rank.order }
+        }
+        // Cannot win this one: lose it with a card that is not a point.
+        return cards.minBy { pointsOf(it) * 100 + it.rank.order }
+    }
+
+    /** Another seat that has taken every penalty card so far and looks set to run the table. */
+    private fun moonThreat(state: HeartsState, seat: Int): Int? {
+        if (!state.options.allowShootTheMoon) return null
+        val all = pointsIn(state.taken.flatten())
+        if (all < 14 && !(state.trickNumber >= 6 && all >= 8)) return null
+        return (0 until state.options.playerCount).firstOrNull {
+            it != seat && pointsIn(state.taken[it]) == all
+        }
+    }
+
+    private fun scoreLeader(state: HeartsState, seat: Int): Int? =
+        (0 until state.options.playerCount).filter { it != seat }.minByOrNull { state.scores[it] }
+
+    private fun hardLead(cards: List<Card>, mem: Memory, profile: AiProfile): Card {
+        // A cautious seat weighs a trick it might win more heavily than a bold one.
+        val weight = 1.0 - 0.25 * profile.style.boldness
+
+        fun risk(card: Card): Double {
+            val others = mem.unseenIn(card.suit)
+            val higher = mem.unseenHigher(card)
+            val winChance = if (others == 0) 1.0 else Math.pow(1.0 - higher.toDouble() / others, 3.0)
+            var points = 0.5
+            if (card.suit == Suit.HEARTS) points += 2.0
+            if (card.suit == Suit.SPADES && mem.queenUnseen) points += 13 * 0.3
+            // A suit nobody else holds lets everyone dump on whoever wins it.
+            if (others == 0) points += 3.0
+            val shedding = if (winChance < 0.15) 0.05 * card.rank.order else 0.0
+            return winChance * points * weight - shedding
+        }
+        return cards.minBy { risk(it) }
+    }
+
+    private fun hardFollow(
+        state: HeartsState,
+        seat: Int,
+        cards: List<Card>,
+        mem: Memory,
+        profile: AiProfile,
+    ): Card {
+        val trick = state.trick
+        val led = trick.first().card.suit
+        val winner = trick.maxBy { trickStrength(it.card, led) }
+        val best = trickStrength(winner.card, led)
+        val pot = pointsIn(trick.map { it.card })
+        val remaining = state.options.playerCount - trick.size - 1
+        val winning = cards.filter { trickStrength(it, led) > best }
+        val ducking = cards.filter { trickStrength(it, led) < best }
+        val threat = moonThreat(state, seat)
+
+        // Taking even a few points is far better than letting a moon through.
+        if (threat != null && pot > 0 && winning.isNotEmpty()) {
+            return winning.minBy { it.rank.order }
+        }
+
+        val void = cards.none { it.suit == led }
+        if (void) return hardDischarge(state, seat, cards, mem, profile, winner.seat, threat)
+
+        if (ducking.isNotEmpty()) {
+            return ducking.maxBy { it.rank.order + pointsOf(it) * 2 }
+        }
+        // Forced to win. Last to play, the trick is taken whatever is played,
+        // so spend the highest card; otherwise win as cheaply as possible.
+        return if (remaining == 0) {
+            cards.maxBy { it.rank.order }
+        } else {
+            cards.minBy { it.rank.order }
+        }
+    }
+
+    /** Void in the led suit: throw away whatever is still dangerous to hold. */
+    private fun hardDischarge(
+        state: HeartsState,
+        seat: Int,
+        cards: List<Card>,
+        mem: Memory,
+        profile: AiProfile,
+        winnerSeat: Int,
+        threat: Int?,
+    ): Card {
+        val spoil = profile.style.spite >= 0.5 && winnerSeat == scoreLeader(state, seat)
+
+        fun score(card: Card): Double {
+            var s: Double = when {
+                card == QUEEN_OF_SPADES -> 1000.0
+                else -> card.rank.order.toDouble()
+            }
+            // The ace and king of spades only matter while the queen is out there.
+            if (card.suit == Suit.SPADES && card.rank.order > Rank.QUEEN.order && mem.queenUnseen) s += 200
+            if (card.suit == Suit.HEARTS) s += 100
+            if (pointsOf(card) == 0 && mem.hand.count { it.suit == card.suit } <= 2) s += 10
+            if (spoil && pointsOf(card) > 0) s += 300
+            // Do not feed a seat that is running for the moon.
+            if (threat != null && winnerSeat == threat && pointsOf(card) > 0) s -= 2000
+            return s
+        }
+        return cards.maxBy { score(it) }
+    }
+
+    private companion object {
+        val FULL_DECK: List<Card> = Suit.entries.flatMap { suit -> Rank.standard.map { Card(it, suit) } }
     }
 }

app/src/main/java/org/prolibertate/games/game/kaiser/KaiserAi.kt

@@ -3,6 +3,10 @@ package org.prolibertate.games.game.kaiser
 import org.prolibertate.games.game.cards.Card
 import org.prolibertate.games.game.cards.Rank
 import org.prolibertate.games.game.cards.Suit
+import org.prolibertate.games.game.cards.Decks
+import org.prolibertate.games.game.engine.AiLevel
+import org.prolibertate.games.game.engine.AiProfile
+import org.prolibertate.games.game.engine.AiProfiles
 import org.prolibertate.games.game.engine.GameAi
 
 /**
@@ -12,25 +16,51 @@ import org.prolibertate.games.game.engine.GameAi
  * in play chases the five of hearts while trying not to be the one holding the
  * trick the three of spades lands in.
  */
-class KaiserAi(private val difficulty: Difficulty = Difficulty.NORMAL) :
+class KaiserAi(private val profiles: AiProfiles = AiProfiles.DEFAULT) :
     GameAi<KaiserState, KaiserMove> {
 
-    enum class Difficulty(
+    private companion object {
         /** Hand strength needed before bidding above the floor. */
-        val bidThreshold: Int,
-    ) {
-        EASY(bidThreshold = 12),
-        NORMAL(bidThreshold = 16),
-        CAUTIOUS(bidThreshold = 19),
+        const val BID_THRESHOLD = 16.0
+        const val EASY_BID_THRESHOLD = 15.0
+    }
+
+    /** Cards this AI has watched played in the current hand, per seat it plays. */
+    private val memory = HashMap<Int, SeenCards>()
+
+    private class SeenCards {
+        var key: Long = Long.MIN_VALUE
+        val cards = HashSet<Card>()
+    }
+
+    /** Public information only: cards that have appeared on the table this hand. */
+    private fun observe(state: KaiserState, seat: Int): Set<Card> = synchronized(memory) {
+        val seen = memory.getOrPut(seat) { SeenCards() }
+        val key = state.seed * 1_000_003L + state.handNumber
+        if (key != seen.key || state.phase == KaiserPhase.BIDDING) {
+            seen.key = key
+            seen.cards.clear()
+        }
+        state.trick.forEach { seen.cards.add(it.card) }
+        state.completedTrick.forEach { seen.cards.add(it.card) }
+        seen.cards.removeAll(state.hands[seat].toSet())
+        seen.cards.toSet()
     }
 
     override fun chooseMove(state: KaiserState, seat: Int, legal: List<KaiserMove>): KaiserMove {
         require(legal.isNotEmpty()) { "No legal move for seat $seat" }
-        return when (state.phase) {
-            KaiserPhase.BIDDING -> chooseBid(state, seat, legal)
-            KaiserPhase.PLAYING -> choosePlay(state, seat, legal)
-            else -> legal.first()
+        val profile = profiles.of(seat)
+        val seen = if (profile.level == AiLevel.HARD) observe(state, seat) else emptySet()
+        val move = try {
+            when (state.phase) {
+                KaiserPhase.BIDDING -> chooseBid(state, seat, legal, profile)
+                KaiserPhase.PLAYING -> choosePlay(state, seat, legal, profile, seen)
+                else -> legal.first()
+            }
+        } catch (e: RuntimeException) {
+            legal.first()
         }
+        return if (move in legal) move else legal.first()
     }
 
     /** Trump length and top cards, plus a nod to holding the counters. */
@@ -50,41 +80,137 @@ class KaiserAi(private val difficulty: Difficulty = Difficulty.NORMAL) :
         return value
     }
 
-    private fun chooseBid(state: KaiserState, seat: Int, legal: List<KaiserMove>): KaiserMove {
+    /**
+     * A finer rating on the same scale as [suitValue]: it rewards a run of top
+     * trump, short side suits to ruff with, and only counts the five of hearts
+     * when the hand can protect it.
+     */
+    private fun hardValue(hand: List<Card>, trump: Suit): Int {
+        val trumps = hand.filter { it.suit == trump }
+        var value = trumps.size * 3
+        for (card in trumps) {
+            value += when (card.rank) {
+                Rank.ACE -> 4
+                Rank.KING -> 3
+                Rank.QUEEN -> 1
+                else -> 0
+            }
+        }
+        // A king backed by the ace, or a queen backed by both, is a real trick.
+        val ranks = trumps.map { it.rank.order }.toSet()
+        if (Rank.ACE.order in ranks && Rank.KING.order in ranks) value += 2
+        if (Rank.ACE.order in ranks && Rank.KING.order in ranks && Rank.QUEEN.order in ranks) value += 1
+
+        for (card in hand) {
+            if (card.suit == trump) continue
+            if (card.rank == Rank.ACE) value += 2
+            else if (card.rank == Rank.KING && hand.any { it.suit == card.suit && it.rank == Rank.ACE }) value += 1
+        }
+        if (trumps.size >= 3) {
+            value += Suit.entries.filter { it != trump }.count { suit -> hand.none { it.suit == suit } } * 2
+        }
+        if (hand.contains(FIVE_OF_HEARTS)) {
+            val guarded = trump == Suit.HEARTS ||
+                hand.any { it.suit == Suit.HEARTS && it.rank == Rank.ACE }
+            value += if (guarded) 3 else -1
+        }
+        if (hand.contains(THREE_OF_SPADES)) value -= if (trump == Suit.SPADES) 1 else 2
+        return value
+    }
+
+    private fun chooseBid(
+        state: KaiserState,
+        seat: Int,
+        legal: List<KaiserMove>,
+        profile: AiProfile,
+    ): KaiserMove {
+        val hand = state.hands[seat]
+        val hard = profile.level == AiLevel.HARD
+        val easy = profile.level == AiLevel.EASY
+
         val naming = legal.filterIsInstance<NameTrump>()
         if (naming.isNotEmpty()) {
-            val hand = state.hands[seat]
-            val best = naming
-                .filter { it.suit != null }
-                .maxByOrNull { suitValue(hand, it.suit!!) }
-            return best ?: naming.first()
+            val named = naming.filter { it.suit != null }
+            return when {
+                hard -> named.maxByOrNull { hardValue(hand, it.suit!!) }
+                easy -> {
+                    val noisy = named.associateWith { suitValue(hand, it.suit!!) + profile.random.nextInt(-4, 5) }
+                    named.sortedByDescending { noisy.getValue(it) }.let { if (it.isEmpty()) null else profile.pick(it) }
+                }
+                else -> named.maxByOrNull { suitValue(hand, it.suit!!) }
+            } ?: naming.first()
         }
 
-        val hand = state.hands[seat]
-        val bestSuit = Suit.entries.maxByOrNull { suitValue(hand, it) } ?: Suit.SPADES
-        val strength = suitValue(hand, bestSuit)
+        val bestSuit: Suit
+        val strength: Int
+        if (hard) {
+            bestSuit = Suit.entries.maxBy { hardValue(hand, it) }
+            strength = hardValue(hand, bestSuit)
+        } else {
+            bestSuit = Suit.entries.maxByOrNull { suitValue(hand, it) } ?: Suit.SPADES
+            strength = suitValue(hand, bestSuit) + if (easy) profile.random.nextInt(-5, 6) else 0
+        }
 
         val bids = legal.filterIsInstance<MakeBid>().filter { !it.bid.noTrump }
-        if (strength >= difficulty.bidThreshold && bids.isNotEmpty()) {
+        var needed = profile.bolder(if (easy) EASY_BID_THRESHOLD else BID_THRESHOLD, -4.0)
+        // A spoiler steals contracts from the other side.
+        val bidder = state.highBidder
+        if (bidder != null && teamOf(bidder) != teamOf(seat) && profile.style.spite >= 0.5) needed -= 2.0
+        if (hard && bids.isNotEmpty()) {
+            val cheapest = bids.minBy { it.bid.points }
+            // A bigger contract needs a bigger hand, and a partner who is
+            // already bidding is better supported than outbid.
+            needed += 2.0 * (cheapest.bid.points - state.options.minimumBid)
+            if (bidder != null && bidder == partnerOf(seat)) needed += 4.0
+        }
+        if (strength >= needed && bids.isNotEmpty()) {
             // Bid the floor rather than reaching; the contract is what matters.
             return bids.minBy { it.bid.points }
         }
         return legal.firstOrNull { it is PassBid } ?: bids.minByOrNull { it.bid.points } ?: legal.first()
     }
 
-    private fun choosePlay(state: KaiserState, seat: Int, legal: List<KaiserMove>): KaiserMove {
+    private fun choosePlay(
+        state: KaiserState,
+        seat: Int,
+        legal: List<KaiserMove>,
+        profile: AiProfile,
+        seen: Set<Card>,
+    ): KaiserMove {
         val cards = legal.filterIsInstance<PlayCard>().map { it.card }
         if (cards.size == 1) return PlayCard(cards.first())
 
+        val bidder = state.highBidder
+        val defending = bidder != null && teamOf(bidder) != teamOf(seat)
+        val spiteful = defending && profile.style.spite >= 0.5
+        val best = if (profile.level == AiLevel.HARD) {
+            hardPlay(state, seat, cards, seen, bidder != null && !defending)
+        } else {
+            standardPlay(state, seat, cards, spiteful, profile)
+        }
+        if (profile.level != AiLevel.EASY) return PlayCard(best)
+
+        // Easy sometimes throws a high card, or a counter, at the wrong time.
+        val ranked = listOf(best) + (cards - best).sortedByDescending { it.rank.order }
+        return PlayCard(profile.pick(ranked))
+    }
+
+    private fun standardPlay(
+        state: KaiserState,
+        seat: Int,
+        cards: List<Card>,
+        spiteful: Boolean,
+        profile: AiProfile,
+    ): Card {
         if (state.trick.isEmpty()) {
             // Leading: pull with the top trump, else lead an ace.
             val trump = state.trump
             val topTrump = cards.filter { trump != null && it.suit == trump }
                 .maxByOrNull { it.rank.order }
-            if (topTrump != null && topTrump.rank.order >= Rank.KING.order) return PlayCard(topTrump)
+            if (topTrump != null && topTrump.rank.order >= Rank.KING.order) return topTrump
             val ace = cards.filter { it.rank == Rank.ACE }.maxByOrNull { it.rank.order }
-            if (ace != null) return PlayCard(ace)
-            return PlayCard(cards.minBy { it.rank.order })
+            if (ace != null) return ace
+            return cards.minBy { it.rank.order }
         }
 
         val ledSuit = state.trick.first().card.suit
@@ -96,22 +222,129 @@ class KaiserAi(private val difficulty: Difficulty = Difficulty.NORMAL) :
         // The five of hearts is worth more than the trick it rides in on.
         val fiveOnTable = state.trick.any { it.card == FIVE_OF_HEARTS }
         val threeOnTable = state.trick.any { it.card == THREE_OF_SPADES }
+        // A spoiler on the defence will not leave a trick to a partner who may be beaten.
+        val notLast = state.trick.size < 3
+        val letPartner = partnerWinning && !threeOnTable &&
+            !(spiteful && notLast && winners.isNotEmpty()) && !profile.slips()
 
         return when {
             // Partner has it and the trick is worth taking: let them have it,
             // unless the three of spades is in there.
-            partnerWinning && !threeOnTable -> PlayCard(cards.minBy { it.rank.order })
+            letPartner -> cards.minBy { it.rank.order }
 
             fiveOnTable && winners.isNotEmpty() ->
-                PlayCard(winners.maxBy { trickStrength(it, state.trump, ledSuit) })
+                winners.maxBy { trickStrength(it, state.trump, ledSuit) }
 
             // Nobody wants the three; duck if the trick is already lost.
-            threeOnTable && winners.isEmpty() -> PlayCard(cards.minBy { it.rank.order })
+            threeOnTable && winners.isEmpty() -> cards.minBy { it.rank.order }
 
             winners.isNotEmpty() && !threeOnTable ->
-                PlayCard(winners.minBy { trickStrength(it, state.trump, ledSuit) })
+                winners.minBy { trickStrength(it, state.trump, ledSuit) }
 
-            else -> PlayCard(cards.minBy { it.rank.order })
+            else -> cards.minBy { it.rank.order }
         }
     }
+
+    /**
+     * The strong player's choice: it remembers what has been played, so it
+     * knows which of its cards are sure winners, feeds the five of hearts to a
+     * partner who is safe, and buries the three of spades under the other side.
+     */
+    private fun hardPlay(
+        state: KaiserState,
+        seat: Int,
+        cards: List<Card>,
+        seen: Set<Card>,
+        bidding: Boolean,
+    ): Card {
+        val trump = state.trump
+        val hand = state.hands[seat]
+        val unseen = Decks.kaiser().filter { it !in seen && it !in hand }
+        val counters = setOf(FIVE_OF_HEARTS, THREE_OF_SPADES)
+
+        fun isBoss(card: Card): Boolean {
+            val mine = trickStrength(card, trump, card.suit)
+            val cardIsTrump = trump != null && card.suit == trump
+            return unseen.none { other ->
+                (cardIsTrump || trump == null || other.suit != trump) &&
+                    trickStrength(other, trump, card.suit) > mine
+            }
+        }
+
+        if (state.trick.isEmpty()) {
+            val plain = cards.filter { it !in counters }.ifEmpty { return cards.minBy { it.rank.order } }
+            val myTrump = plain.filter { trump != null && it.suit == trump }
+            val unseenTrump = unseen.count { trump != null && it.suit == trump }
+            val bossTrump = myTrump.filter { isBoss(it) }.maxByOrNull { it.rank.order }
+            if (bidding && unseenTrump > 0 && bossTrump != null) return bossTrump
+            plain.filter { it !in myTrump && isBoss(it) }.maxByOrNull { it.rank.order }?.let { return it }
+            if (bidding && unseenTrump > 0 && myTrump.size >= 2) return myTrump.maxBy { it.rank.order }
+            if (bossTrump != null) return bossTrump
+            val counts = hand.groupingBy { it.suit }.eachCount()
+            val offSuit = plain.filter { it !in myTrump }.ifEmpty { plain }
+            // The bidders draw a suit out; the defenders shorten one to ruff.
+            return if (bidding) {
+                offSuit.minWith(compareBy<Card>({ -(counts[it.suit] ?: 0) }, { it.rank.order }))
+            } else {
+                offSuit.minWith(compareBy<Card>({ counts[it.suit] ?: 0 }, { it.rank.order }))
+            }
+        }
+
+        val ledSuit = state.trick.first().card.suit
+        val best = state.trick.maxBy { trickStrength(it.card, trump, ledSuit) }
+        val partnerWinning = partnerOf(best.seat) == seat
+        val remaining = 4 - state.trick.size - 1
+        val bestStrength = trickStrength(best.card, trump, ledSuit)
+        val winners = cards.filter { trickStrength(it, trump, ledSuit) > bestStrength }
+        val fiveOnTable = state.trick.any { it.card == FIVE_OF_HEARTS }
+        val threeOnTable = state.trick.any { it.card == THREE_OF_SPADES }
+
+        fun sure(card: Card): Boolean =
+            remaining == 0 ||
+                unseen.none { trickStrength(it, trump, ledSuit) > trickStrength(card, trump, ledSuit) }
+
+        fun throwAway(): Card {
+            val plain = cards.filter { it !in counters }
+            if (plain.isNotEmpty()) return plain.minBy { it.rank.order }
+            // Only counters left: the five belongs with partner, the three does not.
+            return if (partnerWinning) cards.maxBy { it.rank.order } else cards.minBy { it.rank.order }
+        }
+
+        if (partnerWinning) {
+            if (sure(best.card)) {
+                // Partner has it: feed them the five of hearts if we can.
+                if (FIVE_OF_HEARTS in cards && trickStrength(FIVE_OF_HEARTS, trump, ledSuit) <= bestStrength) {
+                    return FIVE_OF_HEARTS
+                }
+                return throwAway()
+            }
+            if (!threeOnTable) {
+                winners.filter { sure(it) }.minByOrNull { trickStrength(it, trump, ledSuit) }?.let { return it }
+            }
+            return throwAway()
+        }
+
+        // The other side is winning.
+        if (threeOnTable) return throwAway()
+        if (fiveOnTable && winners.isNotEmpty()) {
+            val safe = winners.filter { sure(it) }
+            return if (safe.isNotEmpty()) {
+                safe.minBy { trickStrength(it, trump, ledSuit) }
+            } else {
+                winners.maxBy { trickStrength(it, trump, ledSuit) }
+            }
+        }
+        // Bury the three under a trick the other side is certain to take.
+        if (THREE_OF_SPADES in cards &&
+            trickStrength(THREE_OF_SPADES, trump, ledSuit) <= bestStrength &&
+            sure(best.card)
+        ) {
+            return THREE_OF_SPADES
+        }
+        if (winners.isNotEmpty()) {
+            val safe = winners.filter { sure(it) }
+            return (safe.ifEmpty { winners }).minBy { trickStrength(it, trump, ledSuit) }
+        }
+        return throwAway()
+    }
 }

app/src/main/java/org/prolibertate/games/game/mastermind/MastermindAi.kt

@@ -1,6 +1,8 @@
 package org.prolibertate.games.game.mastermind
 
 import kotlin.random.Random
+import org.prolibertate.games.game.engine.AiLevel
+import org.prolibertate.games.game.engine.AiProfiles
 import org.prolibertate.games.game.engine.GameAi
 
 /**
@@ -16,9 +18,18 @@ import org.prolibertate.games.game.engine.GameAi
  * - **Strong** is Knuth's idea one ply deep: among the codes still standing, it
  *   plays the one whose *worst* possible answer leaves the smallest number of
  *   candidates behind, so it cannot be given a reply that tells it little.
+ *
+ * The computer difficulty chosen at setup picks the level: Easy plays Casual,
+ * Medium plays whatever the table's saved [MastermindOptions.level] says (Club
+ * for a new game) and Hard plays Strong. [level] overrides all of that, which is
+ * what the tests use.
  */
-class MastermindAi(private val level: MastermindLevel? = null) :
-    GameAi<MastermindState, MastermindMove> {
+class MastermindAi(
+    private val profiles: AiProfiles = AiProfiles.DEFAULT,
+    private val level: MastermindLevel? = null,
+) : GameAi<MastermindState, MastermindMove> {
+
+    constructor(level: MastermindLevel?) : this(AiProfiles.DEFAULT, level)
 
     override fun chooseMove(
         state: MastermindState,
@@ -26,7 +37,12 @@ class MastermindAi(private val level: MastermindLevel? = null) :
         legal: List<MastermindMove>,
     ): MastermindMove {
         require(legal.isNotEmpty()) { "No legal guess for seat $seat" }
-        val setting = level ?: state.options.level
+        val profile = profiles.of(seat)
+        val setting = level ?: when (profile.level) {
+            AiLevel.EASY -> MastermindLevel.CASUAL
+            AiLevel.MEDIUM -> state.options.level
+            AiLevel.HARD -> MastermindLevel.STRONG
+        }
 
         // Deterministic for a given position, so a host and a client watching
         // the same game agree on what the computer did.

app/src/main/java/org/prolibertate/games/game/morris/MorrisAi.kt

@@ -1,6 +1,9 @@
 package org.prolibertate.games.game.morris
 
 import kotlin.random.Random
+import kotlin.math.roundToInt
+import org.prolibertate.games.game.engine.AiLevel
+import org.prolibertate.games.game.engine.AiProfiles
 import org.prolibertate.games.game.engine.GameAi
 
 /**
@@ -19,7 +22,20 @@ import org.prolibertate.games.game.engine.GameAi
  *
  * Strength comes from the table's own options unless a level is passed in.
  */
-class MorrisAi(private val level: MorrisLevel? = null) : GameAi<MorrisState, MorrisMove> {
+class MorrisAi(
+    private val profiles: AiProfiles = AiProfiles.DEFAULT,
+    private val level: MorrisLevel? = null,
+) : GameAi<MorrisState, MorrisMove> {
+
+    // Viewpoint and weights for the move being chosen. At the default (balanced)
+    // style they equal the plain constants, so Medium is unchanged.
+    private var rootSeat = 0
+    private var wMill = MILL
+    private var wAlmost = ALMOST
+    private var wTheirAlmost = ALMOST
+    private var wMobility = MOBILITY
+    private var wTheirMobility = MOBILITY
+    private var wDanger = DANGER
 
     /**
      * Ceiling on how much thinking any one move gets, so a phone does not stall
@@ -32,10 +48,29 @@ class MorrisAi(private val level: MorrisLevel? = null) : GameAi<MorrisState, Mor
 
     override fun chooseMove(state: MorrisState, seat: Int, legal: List<MorrisMove>): MorrisMove {
         require(legal.isNotEmpty()) { "No legal move for seat $seat" }
+        val profile = profiles.of(seat)
         val setting = level ?: state.options.level
         if (legal.size == 1) return legal.first()
 
-        nodeBudget = NODE_BUDGET
+        val bold = profile.style.boldness
+        val spite = profile.style.spite
+        rootSeat = seat
+        // Bold seats value mills and half-built mills more; cautious ones value
+        // mobility and avoiding the three-piece trap. Spiteful seats weigh the
+        // opponent's mill threats and freedom of movement more.
+        wMill = MILL + (bold * 6).roundToInt()
+        wAlmost = ALMOST + (bold * 3).roundToInt()
+        wTheirAlmost = ALMOST + (spite * 4).roundToInt() + (-bold * 2).roundToInt()
+        wMobility = MOBILITY + (-bold * 1).roundToInt()
+        wTheirMobility = MOBILITY + (spite * 2).roundToInt() + (-bold * 1).roundToInt()
+        wDanger = DANGER + (-bold * 10).roundToInt()
+
+        val maxDepth = when (profile.level) {
+            AiLevel.EASY -> maxOf(2, setting.depth - 2)
+            AiLevel.MEDIUM -> setting.depth
+            AiLevel.HARD -> setting.depth + 1
+        }
+        nodeBudget = if (profile.level == AiLevel.HARD) HARD_NODE_BUDGET else NODE_BUDGET
         nodesUsed = 0
 
         // Deterministic for a given position, so a host and a client replaying
@@ -46,7 +81,7 @@ class MorrisAi(private val level: MorrisLevel? = null) : GameAi<MorrisState, Mor
         var best = legal.first()
         var scored = legal.map { it to 0 }
 
-        for (depth in 1..setting.depth) {
+        for (depth in 1..maxDepth) {
             val results = mutableListOf<Pair<MorrisMove, Int>>()
             val ordered = order(legal, preferred = best)
             for (move in ordered) {
@@ -73,7 +108,16 @@ class MorrisAi(private val level: MorrisLevel? = null) : GameAi<MorrisState, Mor
 
         val bestScore = scored.maxOf { it.second }
         val acceptable = scored.filter { it.second >= bestScore - setting.slack() }
-        return acceptable[random.nextInt(acceptable.size)].first
+        val chosen = acceptable[random.nextInt(acceptable.size)].first
+        if (profile.level != AiLevel.EASY) return chosen
+
+        // Easy now and then settles for another sound-looking move: only ones
+        // within about a piece of the best, never a real blunder.
+        val ranked = listOf(chosen) + scored
+            .filter { it.first != chosen && it.second >= bestScore - EASY_TOLERANCE }
+            .sortedByDescending { it.second }
+            .map { it.first }
+        return profile.pick(ranked)
     }
 
     /** How far below best a move may score and still be considered. */
@@ -155,16 +199,17 @@ class MorrisAi(private val level: MorrisLevel? = null) : GameAi<MorrisState, Mor
 
     /** The position from the point of view of the side to move. */
     private fun evaluate(state: MorrisState): Int {
-        val us = state.turn
-        val them = other(us)
+        val me = rootSeat
+        val them = other(me)
 
-        var score = PIECE * (state.remaining(us) - state.remaining(them))
-        score += MILL * (state.millCount(us) - state.millCount(them))
-        score += ALMOST * (almostMills(state, us) - almostMills(state, them))
-        score += MOBILITY * (mobility(state, us) - mobility(state, them))
-        score += LADDER * (midEdgeCount(state, us) - midEdgeCount(state, them))
-        score -= DANGER * (onThree(state, us) - onThree(state, them))
-        return score
+        var score = PIECE * (state.remaining(me) - state.remaining(them))
+        score += wMill * (state.millCount(me) - state.millCount(them))
+        score += wAlmost * almostMills(state, me) - wTheirAlmost * almostMills(state, them)
+        score += wMobility * mobility(state, me) - wTheirMobility * mobility(state, them)
+        score += LADDER * (midEdgeCount(state, me) - midEdgeCount(state, them))
+        score -= wDanger * (onThree(state, me) - onThree(state, them))
+        // Scored from the root seat's side; flip for the side to move.
+        return if (state.turn == me) score else -score
     }
 
     /**
@@ -215,6 +260,8 @@ class MorrisAi(private val level: MorrisLevel? = null) : GameAi<MorrisState, Mor
         const val INFINITY = 1_000_000
         const val WIN = 100_000
         const val NODE_BUDGET = 120_000
+        const val HARD_NODE_BUDGET = 280_000
+        const val EASY_TOLERANCE = 120
 
         const val PIECE = 120
         const val MILL = 26

app/src/main/java/org/prolibertate/games/game/pirates/PiratesAi.kt

@@ -1,6 +1,10 @@
 package org.prolibertate.games.game.pirates
 
+import kotlin.math.roundToInt
 import kotlin.random.Random
+import org.prolibertate.games.game.engine.AiLevel
+import org.prolibertate.games.game.engine.AiProfile
+import org.prolibertate.games.game.engine.AiProfiles
 import org.prolibertate.games.game.engine.GameAi
 
 /**
@@ -14,17 +18,73 @@ import org.prolibertate.games.game.engine.GameAi
  * from the Bulgars' side and negated for the pirates, so the two cannot drift
  * apart and start valuing the same position differently.
  */
-class PiratesAi(private val level: PiratesLevel? = null) : GameAi<PiratesState, PiratesMove> {
+class PiratesAi(
+    private val profiles: AiProfiles = AiProfiles.DEFAULT,
+    private val level: PiratesLevel? = null,
+) : GameAi<PiratesState, PiratesMove> {
 
     private var nodeBudget = 0
     private var nodesUsed = 0
 
+    // Evaluation weights for the seat now choosing; the standard values unless
+    // a style or level bends them. Set at the top of each chooseMove.
+    private var wBulgar = BULGAR
+    private var wStronghold = IN_STRONGHOLD
+    private var wAdvance = ADVANCE
+    private var wExposed = EXPOSED
+    private var wRoom = PIRATE_ROOM
+
+    private fun tune(profile: AiProfile, seat: Int) {
+        val bold = profile.style.boldness
+        val spite = profile.style.spite
+        var bulgar = 1.0
+        var stronghold = 1.0
+        var advance = 1.0
+        var exposed = 1.0
+        var room = 1.0
+        if (seat == BULGAR_SEAT) {
+            // A bold crowd pushes forward and risks being jumped; a cautious one stays tight.
+            exposed -= 0.3 * bold
+            advance += 0.3 * bold
+            // A spoiler squeezes the pirates' room.
+            room += 0.4 * spite
+        } else {
+            // A bold pirate hunts; a cautious one keeps its room to move.
+            bulgar += 0.15 * bold
+            room -= 0.3 * bold
+            // A spoiler pays more attention to stopping the climb.
+            stronghold += 0.4 * spite
+            advance += 0.4 * spite
+        }
+        if (profile.level == AiLevel.EASY) exposed *= 0.5 // overlooks some threats
+        wBulgar = (BULGAR * bulgar).roundToInt()
+        wStronghold = (IN_STRONGHOLD * stronghold).roundToInt()
+        wAdvance = (ADVANCE * advance).roundToInt()
+        wExposed = (EXPOSED * exposed).roundToInt()
+        wRoom = (PIRATE_ROOM * room).roundToInt()
+    }
+
     override fun chooseMove(state: PiratesState, seat: Int, legal: List<PiratesMove>): PiratesMove {
         require(legal.isNotEmpty()) { "No legal move for seat $seat" }
-        val setting = level ?: state.options.level
         if (legal.size == 1) return legal.first()
+        val profile = profiles.of(seat)
+        val base = level ?: state.options.level
+        tune(profile, seat)
 
-        nodeBudget = NODE_BUDGET
+        val hard = profile.level == AiLevel.HARD
+        val easy = profile.level == AiLevel.EASY
+        val maxDepth = when (profile.level) {
+            AiLevel.MEDIUM -> base.depth
+            AiLevel.EASY -> minOf(base.depth, 2)
+            AiLevel.HARD -> base.depth + 2
+        }
+        val slack = when (profile.level) {
+            AiLevel.MEDIUM -> base.slack()
+            AiLevel.EASY -> maxOf(base.slack(), 40)
+            AiLevel.HARD -> 0
+        }
+
+        nodeBudget = if (hard) HARD_NODE_BUDGET else NODE_BUDGET
         nodesUsed = 0
 
         val random = Random(state.moveLog.size * 31L + state.positionKey().hashCode())
@@ -32,18 +92,23 @@ class PiratesAi(private val level: PiratesLevel? = null) : GameAi<PiratesState,
         var best = legal.first()
         var scored = legal.map { it to 0 }
 
-        for (depth in 1..setting.depth) {
+        for (depth in 1..maxDepth) {
             val results = mutableListOf<Pair<PiratesMove, Int>>()
             val ordered = order(legal, preferred = best)
+            var bestSoFar = -INFINITY
             for (move in ordered) {
+                // A hard seat only needs the exact value of moves that tie or beat
+                // the best so far, so everything else is searched against a window.
+                val floor = if (hard && results.isNotEmpty()) bestSoFar - 1 else -INFINITY
                 val score = -negamax(
                     state = PiratesRules.advanced(state, move),
                     depth = depth - 1,
                     alpha = -INFINITY,
-                    beta = INFINITY,
+                    beta = -floor,
                     ply = 1,
                 )
                 results += move to score
+                if (score > bestSoFar) bestSoFar = score
                 if (nodesUsed >= nodeBudget) break
             }
             if (nodesUsed >= nodeBudget && results.size < ordered.size) break
@@ -51,9 +116,16 @@ class PiratesAi(private val level: PiratesLevel? = null) : GameAi<PiratesState,
             best = results.maxBy { it.second }.first
         }
 
+        if (easy) {
+            val ranked = scored.sortedByDescending { it.second }.map { it.first }
+            val picked = profile.pick(ranked)
+            if (picked != ranked.first() && picked in legal) return picked
+        }
+
         val bestScore = scored.maxOf { it.second }
-        val acceptable = scored.filter { it.second >= bestScore - setting.slack() }
-        return acceptable[random.nextInt(acceptable.size)].first
+        val acceptable = scored.filter { it.second >= bestScore - slack }
+        val chosen = acceptable[random.nextInt(acceptable.size)].first
+        return if (chosen in legal) chosen else legal.first()
     }
 
     private fun PiratesLevel.slack(): Int = when (this) {
@@ -115,22 +187,22 @@ class PiratesAi(private val level: PiratesLevel? = null) : GameAi<PiratesState,
     private fun evaluate(state: PiratesState): Int {
         var bulgarView = 0
 
-        bulgarView += state.count(BULGAR_SEAT) * BULGAR
-        bulgarView += state.stronghold() * IN_STRONGHOLD
+        bulgarView += state.count(BULGAR_SEAT) * wBulgar
+        bulgarView += state.stronghold() * wStronghold
 
         // How far up the board the crowd has come. The stronghold is at the
         // top, so a low row number is ground gained.
         for (point in 0 until POINTS) {
             if (state.board[point] != BULGAR_SEAT) continue
-            bulgarView += (GRID - 1 - rowOf(point)) * ADVANCE
+            bulgarView += (GRID - 1 - rowOf(point)) * wAdvance
             // A Bulgar with an empty point directly behind it on a line is one
             // a pirate can jump. Being unjumpable is most of staying alive.
-            if (isExposed(state, point)) bulgarView -= EXPOSED
+            if (isExposed(state, point)) bulgarView -= wExposed
         }
 
         // Room for the pirates to work in, which is what the Bulgars are
         // slowly taking away.
-        bulgarView -= pirateMobility(state) * PIRATE_ROOM
+        bulgarView -= pirateMobility(state) * wRoom
 
         return if (state.turn == BULGAR_SEAT) bulgarView else -bulgarView
     }
@@ -160,6 +232,7 @@ class PiratesAi(private val level: PiratesLevel? = null) : GameAi<PiratesState,
         const val INFINITY = 1_000_000
         const val WIN = 100_000
         const val NODE_BUDGET = 150_000
+        const val HARD_NODE_BUDGET = 400_000
 
         const val BULGAR = 100
         const val IN_STRONGHOLD = 55

app/src/main/java/org/prolibertate/games/game/president/PresidentAi.kt

@@ -1,63 +1,85 @@
 package org.prolibertate.games.game.president
 
+import org.prolibertate.games.game.cards.Card
+import org.prolibertate.games.game.cards.Rank
+import org.prolibertate.games.game.cards.Suit
+import org.prolibertate.games.game.engine.AiLevel
+import org.prolibertate.games.game.engine.AiProfile
+import org.prolibertate.games.game.engine.AiProfiles
 import org.prolibertate.games.game.engine.GameAi
 
 /**
- * A heuristic President opponent.
+ * A President opponent whose strength and temperament come from the seat's profile.
  *
- * It sheds low cards early, spends the cheapest set that takes the pile, and
- * holds twos back for when they are worth something. It does not count cards.
+ * MEDIUM (the default) sheds low cards early, spends the cheapest set that takes
+ * the pile, and holds twos back for when they are worth something. It does not
+ * count cards.
+ *
+ * EASY spends high cards freely when leading and sometimes plays a worse set or
+ * passes when it should have played. HARD reads the round's log to count which
+ * ranks are still out, leads so that its remaining hand is unbeatable, blocks an
+ * opponent who is about to go out, and keeps its high cards back when a cheap
+ * pile is not worth them.
  */
-class PresidentAi(private val difficulty: Difficulty = Difficulty.NORMAL) :
+class PresidentAi(private val profiles: AiProfiles = AiProfiles.DEFAULT) :
     GameAi<PresidentState, PresidentMove> {
 
-    enum class Difficulty(
-        /** Rank above which a card is hoarded rather than spent to lead. */
-        val hoardAbove: Int,
-    ) {
-        /** Plays whatever is cheapest, whenever it can. */
-        EASY(hoardAbove = 99),
-
-        NORMAL(hoardAbove = 13),
-
-        /** Sits on high cards until late, then dumps them. */
-        CAUTIOUS(hoardAbove = 11),
-    }
-
     override fun chooseMove(
         state: PresidentState,
         seat: Int,
         legal: List<PresidentMove>,
     ): PresidentMove {
         require(legal.isNotEmpty()) { "No legal move for seat $seat" }
+        val profile = profiles.of(seat)
         val plays = legal.filterIsInstance<PlayCards>()
         if (plays.isEmpty()) return legal.first()
 
-        return if (state.setSize == 0) chooseLead(state, seat, plays) else chooseFollow(state, plays, legal)
+        val move: PresidentMove = when (profile.level) {
+            AiLevel.MEDIUM -> standard(state, seat, plays, legal, hoardAbove = HOARD_ABOVE)
+            AiLevel.EASY -> easy(state, seat, plays, legal, profile)
+            AiLevel.HARD -> hard(state, seat, plays, legal, profile)
+        }
+        return if (move in legal) move else legal.first()
     }
 
+    private fun standard(
+        state: PresidentState,
+        seat: Int,
+        plays: List<PlayCards>,
+        legal: List<PresidentMove>,
+        hoardAbove: Int,
+    ): PresidentMove =
+        if (state.setSize == 0) {
+            leadRanking(state, seat, plays, hoardAbove).first()
+        } else {
+            chooseFollow(state, plays, legal)
+        }
+
+    // -----------------------------------------------------------------------
+    // Standard plan
+    // -----------------------------------------------------------------------
+
     /**
      * Leading is a chance to shed. Prefer the biggest set of the lowest rank,
      * which clears junk fastest without spending anything valuable.
      */
-    private fun chooseLead(
+    private fun leadRanking(
         state: PresidentState,
         seat: Int,
         plays: List<PlayCards>,
-    ): PresidentMove {
+        hoardAbove: Int,
+    ): List<PlayCards> {
         val endgame = state.hands[seat].size <= 4
         val candidates = plays.filter { play ->
-            endgame || presidentRank(play.cards.first()) <= difficulty.hoardAbove
+            endgame || presidentRank(play.cards.first()) <= hoardAbove
         }.ifEmpty { plays }
 
-        return candidates
-            .sortedWith(
-                compareBy(
-                    { presidentRank(it.cards.first()) },
-                    { -it.cards.size },
-                )
-            )
-            .first()
+        return candidates.sortedWith(
+            compareBy<PlayCards>(
+                { presidentRank(it.cards.first()) },
+                { -it.cards.size },
+            ),
+        )
     }
 
     /**
@@ -82,4 +104,188 @@ class PresidentAi(private val difficulty: Difficulty = Difficulty.NORMAL) :
 
         return cheapest
     }
+
+    // -----------------------------------------------------------------------
+    // Easy
+    // -----------------------------------------------------------------------
+
+    private fun easy(
+        state: PresidentState,
+        seat: Int,
+        plays: List<PlayCards>,
+        legal: List<PresidentMove>,
+        profile: AiProfile,
+    ): PresidentMove {
+        if (state.setSize == 0) {
+            // Never hoards: leads aces and twos as readily as anything else.
+            return profile.pick(leadRanking(state, seat, plays, hoardAbove = 99))
+        }
+        val best = chooseFollow(state, plays, legal)
+        val alternatives = plays.sortedBy { presidentRank(it.cards.first()) }
+        val ranked = buildList<PresidentMove> {
+            add(best)
+            addAll(alternatives.filter { it != best })
+            if (PassTurn in legal && best != PassTurn) add(PassTurn)
+        }
+        return profile.pick(ranked)
+    }
+
+    // -----------------------------------------------------------------------
+    // Hard
+    // -----------------------------------------------------------------------
+
+    /** Ranks still unaccounted for: not in this seat's hand and not played yet this round. */
+    private class Counts(state: PresidentState, seat: Int) {
+        private val unseen = HashMap<Int, Int>()
+
+        init {
+            for (rank in 3..15) unseen[rank] = 4
+            state.hands[seat].forEach { dec(presidentRank(it)) }
+            val log = state.log
+            val start = log.indexOfLast { ROUND_MARK.matches(it) } + 1
+            for (i in start until log.size) {
+                val line = log[i]
+                val at = line.indexOf(" plays ")
+                if (!line.startsWith("Seat ") || at < 0) continue
+                line.substring(at + " plays ".length).removeSuffix(".").split(' ').forEach { token ->
+                    LABELS[token]?.let { dec(presidentRank(it)) }
+                }
+            }
+        }
+
+        private fun dec(rank: Int) {
+            unseen[rank] = maxOf(0, (unseen[rank] ?: 0) - 1)
+        }
+
+        fun of(rank: Int): Int = unseen[rank] ?: 0
+
+        /** Could an opponent still hold a set of [size] that beats a set of [size] at [rank]? */
+        fun beatable(rank: Int, size: Int, options: PresidentOptions): Boolean {
+            if (options.twosClear && rank != 15 && of(15) >= size) return true
+            if (options.fourOfAKindBomb && size == 4 && (3..15).any { it != rank && of(it) == 4 }) return true
+            return (rank + 1..15).any { of(it) >= size }
+        }
+    }
+
+    private fun hard(
+        state: PresidentState,
+        seat: Int,
+        plays: List<PlayCards>,
+        legal: List<PresidentMove>,
+        profile: AiProfile,
+    ): PresidentMove {
+        val hand = state.hands[seat]
+        // Going out beats any plan.
+        plays.firstOrNull { it.cards.size == hand.size }?.let { return it }
+
+        val counts = Counts(state, seat)
+        val others = (0 until state.options.playerCount).filter { it != seat && !state.isOut(it) }
+        return if (state.setSize == 0) {
+            hardLead(state, seat, plays, counts, others, profile)
+        } else {
+            hardFollow(state, seat, plays, legal, counts, others, profile)
+        }
+    }
+
+    /** An opponent who could empty their hand with a set the size of the one on top, or is the score leader close to out. */
+    private fun outThreat(
+        state: PresidentState,
+        seat: Int,
+        others: List<Int>,
+        profile: AiProfile,
+    ): Boolean {
+        if (others.any { state.handCounts[it] <= maxOf(1, state.setSize) }) return true
+        if (profile.style.spite >= 0.5) {
+            val leader = others.maxByOrNull { state.scores[it] }
+            if (leader != null && state.handCounts[leader] <= 2) return true
+        }
+        return false
+    }
+
+    private fun hardLead(
+        state: PresidentState,
+        seat: Int,
+        plays: List<PlayCards>,
+        counts: Counts,
+        others: List<Int>,
+        profile: AiProfile,
+    ): PresidentMove {
+        val hand = state.hands[seat]
+        val options = state.options
+        val oneCardLeft = others.any { state.handCounts[it] == 1 }
+
+        fun unbeatableAfter(play: PlayCards): Boolean {
+            val remaining = hand.toMutableList().also { left -> play.cards.forEach { left.remove(it) } }
+            return remaining.groupBy { presidentRank(it) }
+                .all { (rank, cards) -> !counts.beatable(rank, cards.size, options) }
+        }
+
+        fun key(play: PlayCards): Double {
+            val rank = presidentRank(play.cards.first())
+            val size = play.cards.size
+            var k = rank - 0.9 * size
+            if (unbeatableAfter(play)) return k - 50.0
+            // Leading aces and twos spends control that is worth more later.
+            if (rank >= 14 && hand.size > 4) k += 20.0
+            // Somebody is down to one card: a single would let them out if they can beat it.
+            if (oneCardLeft && size == 1) k += 10.0 + (15 - rank) * 2.0
+            // A bold seat is happier to lead its strong sets early.
+            if (rank >= 11) k -= profile.style.boldness * 2.0
+            return k
+        }
+        return plays.minBy { key(it) }
+    }
+
+    private fun hardFollow(
+        state: PresidentState,
+        seat: Int,
+        plays: List<PlayCards>,
+        legal: List<PresidentMove>,
+        counts: Counts,
+        others: List<Int>,
+        profile: AiProfile,
+    ): PresidentMove {
+        val hand = state.hands[seat]
+        val options = state.options
+        val canPass = PassTurn in legal
+        val threat = outThreat(state, seat, others, profile)
+
+        val withoutTwos = plays.filter { play -> play.cards.none { isTwo(it) } }
+        val pool = withoutTwos.ifEmpty { plays }
+        val cheapest = pool.minBy { presidentRank(it.cards.first()) }
+
+        if (threat) {
+            // Block them: take the pile with the cheapest set nobody can beat,
+            // or failing that the cheapest set there is, twos included.
+            val sure = plays.filter { !counts.beatable(presidentRank(it.cards.first()), it.cards.size, options) }
+                .minByOrNull { presidentRank(it.cards.first()) }
+            return sure ?: plays.minBy { presidentRank(it.cards.first()) }
+        }
+
+        val spendingTwo = cheapest.cards.any { isTwo(it) }
+        if (spendingTwo) {
+            val remaining = hand.toMutableList().also { left -> cheapest.cards.forEach { left.remove(it) } }
+            val runOut = remaining.groupBy { presidentRank(it) }
+                .all { (rank, cards) -> !counts.beatable(rank, cards.size, options) }
+            val worthIt = state.setRank >= 13 || state.pile.size >= 4 || hand.size <= 4 || runOut
+            if (!worthIt && canPass) return PassTurn
+            return cheapest
+        }
+
+        // A cheap pile is not worth a high card while the hand is still big.
+        val gap = profile.bolder(6.0, 2.0)
+        val cost = presidentRank(cheapest.cards.first()) - state.setRank
+        if (canPass && hand.size > 5 && cost > gap && presidentRank(cheapest.cards.first()) >= 12) {
+            return PassTurn
+        }
+        return cheapest
+    }
+
+    private companion object {
+        const val HOARD_ABOVE = 13
+        val ROUND_MARK = Regex("^Round \\d+\\.$")
+        val LABELS: Map<String, Card> = Suit.entries.flatMap { suit ->
+            Rank.standard.map { Card(it, suit) }
+        }.associateBy { it.label }
+    }
 }

app/src/main/java/org/prolibertate/games/game/sequence/SequenceAi.kt

@@ -1,5 +1,8 @@
 package org.prolibertate.games.game.sequence
 
+import org.prolibertate.games.game.engine.AiLevel
+import org.prolibertate.games.game.engine.AiProfile
+import org.prolibertate.games.game.engine.AiProfiles
 import org.prolibertate.games.game.engine.GameAi
 
 /**
@@ -8,18 +11,39 @@ import org.prolibertate.games.game.engine.GameAi
  * It scores every legal placement by how much it advances one of its own runs
  * and how badly it spoils an opponent's, holds its jacks back until they are
  * worth spending, and never looks at anyone's hand.
+ *
+ * Per seat, from [profiles]: Easy mostly ignores your runs, burns its one-eyed
+ * jacks on anything and sometimes settles for a lesser square; Hard blocks hard,
+ * saves jacks for real threats, always takes a completed run and always stops
+ * one that is one square from done. Boldness leans towards building over
+ * blocking and spite the other way round.
  */
-class SequenceAi(private val difficulty: Difficulty = Difficulty.NORMAL) :
+class SequenceAi(private val profiles: AiProfiles = AiProfiles.DEFAULT) :
     GameAi<SequenceState, SequenceMove> {
 
-    enum class Difficulty(val blockWeight: Int, val jackPatience: Int) {
-        /** Builds its own runs and mostly ignores yours. */
-        EASY(blockWeight = 1, jackPatience = 0),
+    /** The numbers one seat plays with, worked out from its level and style. */
+    private class Tuning(
+        val ownWeight: Double,
+        val blockWeight: Double,
+        val jackPatience: Double,
+        val finishing: Boolean,
+    )
 
-        NORMAL(blockWeight = 3, jackPatience = 3),
-
-        /** Blocks aggressively and saves jacks for real threats. */
-        CAUTIOUS(blockWeight = 5, jackPatience = 4),
+    private fun tuningOf(profile: AiProfile): Tuning {
+        val (block, patience) = when (profile.level) {
+            AiLevel.EASY -> 1.0 to 0.0
+            AiLevel.MEDIUM -> 3.0 to 3.0
+            AiLevel.HARD -> 5.0 to 4.0
+        }
+        val style = profile.style
+        val easy = profile.level == AiLevel.EASY
+        return Tuning(
+            ownWeight = 4.0 + style.boldness,
+            blockWeight = block - style.boldness * 0.8 + style.spite * 2.0,
+            // Only a seat that is paying attention changes its mind about jacks.
+            jackPatience = if (easy) patience else patience + style.boldness - style.spite,
+            finishing = profile.level == AiLevel.HARD,
+        )
     }
 
     override fun chooseMove(
@@ -28,15 +52,30 @@ class SequenceAi(private val difficulty: Difficulty = Difficulty.NORMAL) :
         legal: List<SequenceMove>,
     ): SequenceMove {
         require(legal.isNotEmpty()) { "No legal move for seat $seat" }
+        val profile = profiles.of(seat)
+        val tuning = tuningOf(profile)
         val team = state.teamOf(seat)
 
         // Clearing a dead card is free value when nothing better is on offer.
         val exchange = legal.filterIsInstance<ExchangeDeadCard>().firstOrNull()
         if (exchange != null && legal.none { it is PlaceChip }) return exchange
 
-        val best = legal
+        val placements = legal
             .filterIsInstance<PlaceChip>()
-            .maxByOrNull { scorePlacement(state, it, team) }
+            .map { it to scorePlacement(state, it, team, tuning) }
+            .sortedByDescending { it.second }
+            .map { it.first }
+        val best = if (placements.isEmpty()) {
+            null
+        } else if (tuning.finishing) {
+            // A run that completes, or a run of the opponent's that would, is
+            // never something to be talked out of.
+            placements.first()
+        } else {
+            // Easy only: the others never slip. Only the better few are in play,
+            // so a slip is a weaker square rather than a wasted card.
+            profile.pick(placements.take(4))
+        }
 
         val removal = legal
             .filterIsInstance<RemoveChip>()
@@ -45,7 +84,7 @@ class SequenceAi(private val difficulty: Difficulty = Difficulty.NORMAL) :
         // Spend a one-eyed jack only on a genuinely dangerous chip.
         if (removal != null) {
             val threat = threatAt(state, removal.cell, state.chips[removal.cell])
-            if (threat >= difficulty.jackPatience) return removal
+            if (threat >= tuning.jackPatience && !profile.slips()) return removal
         }
 
         return best ?: removal ?: exchange ?: legal.first()
@@ -56,14 +95,25 @@ class SequenceAi(private val difficulty: Difficulty = Difficulty.NORMAL) :
      * opponent's run it interrupts. Wild jacks are discounted so they are not
      * burned on an ordinary square.
      */
-    private fun scorePlacement(state: SequenceState, move: PlaceChip, team: Int): Int {
+    private fun scorePlacement(
+        state: SequenceState,
+        move: PlaceChip,
+        team: Int,
+        tuning: Tuning,
+    ): Double {
         val ours = runPotential(state, move.cell, team)
         val theirs = (0 until state.options.teamCount)
             .filter { it != team }
             .maxOfOrNull { runPotential(state, move.cell, it) }
             ?: 0
 
-        var score = ours * 4 + theirs * difficulty.blockWeight
+        var score = ours * tuning.ownWeight + theirs * tuning.blockWeight
+        if (tuning.finishing) {
+            // A potential of five through this square means placing here
+            // completes the run (for whoever places it).
+            if (ours >= RUN_LENGTH) score += 100.0
+            if (theirs >= RUN_LENGTH) score += 60.0 else if (theirs == RUN_LENGTH - 1) score += 8.0
+        }
         // Central squares sit on more possible lines than edge squares.
         val row = SequenceBoard.rowOf(move.cell)
         val col = SequenceBoard.colOf(move.cell)

app/src/main/java/org/prolibertate/games/game/tayu/TayuAi.kt

@@ -1,5 +1,8 @@
 package org.prolibertate.games.game.tayu
 
+import org.prolibertate.games.game.engine.AiLevel
+import org.prolibertate.games.game.engine.AiProfile
+import org.prolibertate.games.game.engine.AiProfiles
 import org.prolibertate.games.game.engine.GameAi
 
 /**
@@ -18,17 +21,53 @@ import org.prolibertate.games.game.engine.GameAi
  *
  * [level] overrides the table's own setting, which is what the tests use;
  * ordinarily it is left null and read from [TayuOptions.level].
+ *
+ * Per seat, from [profiles]: the table's setting says which terms count at all
+ * (Gentle ignores the opponent entirely and that is respected at every level).
+ * Within Full strength, Easy blocks and steers less and sometimes takes one of
+ * its better few placements rather than the best; Hard blocks and steers harder.
+ * Boldness weights its own axis against the opponent's, spite weights blocking.
  */
-class TayuAi(private val level: TayuLevel? = null) : GameAi<TayuState, TayuMove> {
+class TayuAi(
+    private val profiles: AiProfiles = AiProfiles.DEFAULT,
+    private val level: TayuLevel? = null,
+) : GameAi<TayuState, TayuMove> {
+
+    constructor(level: TayuLevel) : this(AiProfiles.DEFAULT, level)
+
+    private class Weights(val own: Double, val block: Double, val reach: Double)
+
+    private fun weightsOf(setting: TayuLevel, profile: AiProfile): Weights {
+        var own = setting.ownWeight.toDouble()
+        var block = setting.blockWeight.toDouble()
+        var reach = setting.reachWeight.toDouble()
+        // Gentle is a table rule, not a skill level: it stays as it is.
+        if (setting.blockWeight > 0) {
+            when (profile.level) {
+                AiLevel.EASY -> { block *= 0.4; reach *= 0.5 }
+                AiLevel.MEDIUM -> Unit
+                AiLevel.HARD -> { block *= 1.35; reach *= 1.5 }
+            }
+            own *= 1.0 + 0.15 * profile.style.boldness
+            block *= 1.0 - 0.15 * profile.style.boldness + 0.4 * profile.style.spite
+        }
+        return Weights(own, block, reach)
+    }
 
     override fun chooseMove(state: TayuState, seat: Int, legal: List<TayuMove>): TayuMove {
         require(legal.isNotEmpty()) { "No legal move for seat $seat" }
+        val profile = profiles.of(seat)
         val setting = level ?: state.options.level
         if (legal.size == 1) return legal.first()
-        return legal.maxByOrNull { rate(state, seat, it, setting) } ?: legal.first()
+        val weights = weightsOf(setting, profile)
+        val rated = legal.map { it to rate(state, seat, it, weights) }
+        if (profile.level != AiLevel.EASY) return rated.maxByOrNull { it.second }?.first ?: legal.first()
+        // Easy: one of its better few placements, not always the best.
+        val ranked = rated.sortedByDescending { it.second }.take(EASY_POOL).map { it.first }
+        return profile.pick(ranked)
     }
 
-    private fun rate(state: TayuState, seat: Int, move: TayuMove, setting: TayuLevel): Int {
+    private fun rate(state: TayuState, seat: Int, move: TayuMove, weights: Weights): Double {
         val after = TayuRules.previewPlacement(state, seat, move)
         val mine = state.axisOf(seat)
         val theirs = if (mine == Axis.NORTH_SOUTH) Axis.EAST_WEST else Axis.NORTH_SOUTH
@@ -43,15 +82,15 @@ class TayuAi(private val level: TayuLevel? = null) : GameAi<TayuState, TayuMove>
         // Skipped rather than multiplied by zero: the gentle setting is the whole
         // reason to avoid walking the open mouths at all, and this runs for every
         // one of a thousand-odd candidate placements.
-        val reach = if (setting.reachWeight == 0) {
+        val reach = if (weights.reach == 0.0) {
             0
         } else {
             (pull(after, mine) - pull(after, theirs)) / REACH_SCALE
         }
 
-        return setting.ownWeight * ours -
-            setting.blockWeight * opposing +
-            setting.reachWeight * reach
+        return weights.own * ours -
+            weights.block * opposing +
+            weights.reach * reach
     }
 
     /**
@@ -82,5 +121,8 @@ class TayuAi(private val level: TayuLevel? = null) : GameAi<TayuState, TayuMove>
     private companion object {
         /** Brings the open-mouth term onto the same scale as the score term. */
         const val REACH_SCALE = 8
+
+        /** How many top-rated placements Easy chooses among. */
+        const val EASY_POOL = 6
     }
 }

app/src/main/java/org/prolibertate/games/game/wizard/WizardAi.kt

@@ -3,8 +3,13 @@ package org.prolibertate.games.game.wizard
 import org.prolibertate.games.game.cards.Card
 import org.prolibertate.games.game.cards.Rank
 import org.prolibertate.games.game.cards.Suit
+import org.prolibertate.games.game.cards.Decks
+import org.prolibertate.games.game.engine.AiLevel
+import org.prolibertate.games.game.engine.AiProfile
+import org.prolibertate.games.game.engine.AiProfiles
 import org.prolibertate.games.game.engine.GameAi
 import kotlin.math.abs
+import kotlin.math.pow
 import kotlin.math.roundToInt
 
 /**
@@ -15,52 +20,99 @@ import kotlin.math.roundToInt
  * high it is and whether it is trump. In play it chases tricks while it is
  * short of its bid and ducks once it has them, which is the whole game.
  */
-class WizardAi(private val difficulty: Difficulty = Difficulty.NORMAL) :
+class WizardAi(private val profiles: AiProfiles = AiProfiles.DEFAULT) :
     GameAi<WizardState, WizardMove> {
 
-    enum class Difficulty(
-        /**
-         * Added to the expected-trick count before rounding. Optimists overbid
-         * and go down; pessimists underbid and get caught taking tricks they
-         * did not want.
-         */
-        val bidBias: Double,
-    ) {
-        EASY(bidBias = 0.35),
-        NORMAL(bidBias = 0.0),
-        CAUTIOUS(bidBias = -0.25),
+    private companion object {
+        /** Optimists overbid and go down; Easy leans this way. */
+        const val EASY_BID_BIAS = 0.35
+        val DECK: List<Card> = Decks.wizard()
+    }
+
+    /** Cards this AI has watched played in the current round, per seat it plays. */
+    private val memory = HashMap<Int, SeenCards>()
+
+    private class SeenCards {
+        var key: Long = Long.MIN_VALUE
+        val cards = HashSet<Card>()
+    }
+
+    /** Public information only: cards that have appeared on the table this round. */
+    private fun observe(state: WizardState, seat: Int): Set<Card> = synchronized(memory) {
+        val seen = memory.getOrPut(seat) { SeenCards() }
+        val key = state.seed * 1_000_003L + state.round
+        if (key != seen.key || state.phase == WizardPhase.BIDDING) {
+            seen.key = key
+            seen.cards.clear()
+        }
+        state.trick.forEach { seen.cards.add(it.card) }
+        state.completedTrick.forEach { seen.cards.add(it.card) }
+        seen.cards.removeAll(state.hands[seat].toSet())
+        seen.cards.toSet()
     }
 
     override fun chooseMove(state: WizardState, seat: Int, legal: List<WizardMove>): WizardMove {
         require(legal.isNotEmpty()) { "No legal move for seat $seat" }
-        return when (state.phase) {
-            WizardPhase.BIDDING -> chooseBid(state, seat, legal)
-            WizardPhase.PLAYING -> choosePlay(state, seat, legal)
-            else -> legal.first()
+        val profile = profiles.of(seat)
+        val seen = if (profile.level == AiLevel.HARD) observe(state, seat) else emptySet()
+        val move = try {
+            when (state.phase) {
+                WizardPhase.BIDDING -> chooseBid(state, seat, legal, profile)
+                WizardPhase.PLAYING -> choosePlay(state, seat, legal, profile, seen)
+                else -> legal.first()
+            }
+        } catch (e: RuntimeException) {
+            legal.first()
         }
+        return if (move in legal) move else legal.first()
     }
 
     // -----------------------------------------------------------------------
     // Bidding
     // -----------------------------------------------------------------------
 
-    private fun chooseBid(state: WizardState, seat: Int, legal: List<WizardMove>): WizardMove {
+    private fun chooseBid(
+        state: WizardState,
+        seat: Int,
+        legal: List<WizardMove>,
+        profile: AiProfile,
+    ): WizardMove {
+        val hand = state.hands[seat]
+        val hard = profile.level == AiLevel.HARD
+        val easy = profile.level == AiLevel.EASY
+
         val naming = legal.filterIsInstance<ChooseTrump>()
         if (naming.isNotEmpty()) {
-            val hand = state.hands[seat]
-            val best = naming.maxByOrNull { suitStrength(hand, it.suit) }
-            return best ?: naming.first()
+            return when {
+                hard -> naming.maxByOrNull { hardExpected(state, hand, it.suit) }
+                easy -> {
+                    val noisy = naming.associateWith { suitStrength(hand, it.suit) + profile.random.nextDouble(-0.8, 0.8) }
+                    profile.pick(naming.sortedByDescending { noisy.getValue(it) })
+                }
+                else -> naming.maxByOrNull { suitStrength(hand, it.suit) }
+            } ?: naming.first()
         }
 
         val bids = legal.filterIsInstance<MakeBid>()
         if (bids.isEmpty()) return legal.first()
 
-        val wanted = (expectedTricks(state.hands[seat], state.trump) + difficulty.bidBias)
-            .roundToInt()
-            .coerceIn(0, state.cardsThisRound)
+        var expected = if (hard) hardExpected(state, hand, state.trump) else expectedTricks(hand, state.trump)
+        if (hard) {
+            // The last to bid knows how many tricks the others have left on the table.
+            val others = state.bids.filterNotNull()
+            if (others.size == state.options.playerCount - 1) {
+                expected = expected * 0.75 + (state.cardsThisRound - others.sum()) * 0.25
+            }
+        }
+        if (easy) expected += EASY_BID_BIAS + profile.random.nextDouble(-0.8, 0.8)
+        // A gambler bids up, a cautious seat bids down.
+        expected += profile.bolder(0.0, 0.3)
+
+        val wanted = expected.roundToInt().coerceIn(0, state.cardsThisRound)
         // Screw-the-dealer may have taken the number we wanted away, so settle
         // for the nearest one still on offer.
-        return bids.minBy { abs(it.tricks - wanted) }
+        val ranked = bids.sortedBy { abs(it.tricks - wanted) }
+        return if (easy) profile.pick(ranked) else ranked.first()
     }
 
     /** How much of a hand a given trump suit would be worth. */
@@ -92,22 +144,88 @@ class WizardAi(private val difficulty: Difficulty = Difficulty.NORMAL) :
         return expected
     }
 
+    /**
+     * The chance [card] takes a trick, from the cards that could still beat it.
+     *
+     * [pool] is every card that might be in somebody else's hand and [q] the
+     * chance any one of them is, and each higher card only threatens the trick
+     * if it lands in the same one, which is less likely the longer the round.
+     */
+    private fun winProb(card: Card, pool: List<Card>, trump: Suit?, q: Double, tricks: Int): Double {
+        if (isWizardCard(card)) return 1.0
+        if (isJester(card)) return 0.0
+        val wizards = pool.count { isWizardCard(it) && it != card }
+        val ordinary = { c: Card -> !isWizardCard(c) && !isJester(c) }
+        val trumpCard = trump != null && card.suit == trump
+        val higher = pool.count { ordinary(it) && it.suit == card.suit && it.rank.order > card.rank.order }
+        var danger = (higher + wizards).toDouble()
+        if (!trumpCard && trump != null) {
+            val voidFactor = 1.0 / (1.0 + 0.5 * (tricks - 1))
+            danger += voidFactor * pool.count { ordinary(it) && it.suit == trump }
+        }
+        val sequencing = 1.0 / (1.0 + 0.35 * (tricks - 1))
+        return (1.0 - (q * sequencing).coerceIn(0.0, 1.0)).pow(danger)
+    }
+
+    /** Expected tricks from the cards that could still be out, calibrated so the average hand scores its fair share. */
+    private fun hardExpected(state: WizardState, hand: List<Card>, trump: Suit?): Double {
+        val n = state.cardsThisRound
+        val players = state.options.playerCount
+        val inPlay = DECK.filter { it != state.trumpCard }
+        val mine = inPlay.filter { it !in hand }
+        val q = ((players - 1) * n).toDouble() / mine.size.coerceAtLeast(1)
+
+        val own = hand.sumOf { winProb(it, mine, trump, q, n) }
+        val average = inPlay.sumOf { winProb(it, inPlay, trump, q, n) } / inPlay.size
+        val scale = if (average > 0.0) (1.0 / (players * average)).coerceIn(0.5, 2.0) else 1.0
+        return own * scale
+    }
+
     // -----------------------------------------------------------------------
     // Play
     // -----------------------------------------------------------------------
 
-    private fun choosePlay(state: WizardState, seat: Int, legal: List<WizardMove>): WizardMove {
+    private fun choosePlay(
+        state: WizardState,
+        seat: Int,
+        legal: List<WizardMove>,
+        profile: AiProfile,
+        seen: Set<Card>,
+    ): WizardMove {
         val cards = legal.filterIsInstance<PlayCard>().map { it.card }
         if (cards.size == 1) return PlayCard(cards.first())
 
+        val hard = profile.level == AiLevel.HARD
         val bid = state.bids[seat] ?: 0
         val stillNeeded = bid - state.tricksWon[seat]
         val tricksLeft = state.hands[seat].size
         // Chase while we are short, and only while there are enough tricks left
-        // to be worth chasing.
-        val wantsTrick = stillNeeded > 0 && stillNeeded <= tricksLeft
+        // to be worth chasing. (The careful player keeps chasing even when the
+        // bid is out of reach: every trick still cuts the penalty.)
+        val wantsTrick = stillNeeded > 0 && (hard || stillNeeded <= tricksLeft)
+        // A spoiler who has already blown their own bid takes tricks off anyone
+        // who needs exactly one more.
+        val spoiling = profile.style.spite >= 0.5 && stillNeeded < 0
 
-        if (state.trick.isEmpty()) return PlayCard(chooseLead(cards, state.trump, wantsTrick))
+        val best = if (hard) {
+            hardPlay(state, seat, cards, seen, wantsTrick, spoiling, stillNeeded, tricksLeft)
+        } else {
+            standardPlay(state, cards, wantsTrick, spoiling)
+        }
+        if (profile.level != AiLevel.EASY) return PlayCard(best)
+
+        // Easy sometimes burns a strong card at the wrong moment.
+        val ranked = listOf(best) + (cards - best).sortedByDescending { it.rank.order }
+        return PlayCard(profile.pick(ranked))
+    }
+
+    private fun standardPlay(
+        state: WizardState,
+        cards: List<Card>,
+        wantsTrick: Boolean,
+        spoiling: Boolean,
+    ): Card {
+        if (state.trick.isEmpty()) return chooseLead(cards, state.trump, wantsTrick)
 
         val ledSuit = ledSuitOf(state.trick)
         val order = state.trick.size
@@ -122,15 +240,99 @@ class WizardAi(private val difficulty: Difficulty = Difficulty.NORMAL) :
 
         return when {
             // Take it as cheaply as we can.
-            wantsTrick && winners.isNotEmpty() -> PlayCard(winners.minBy { strengthOf(it) })
+            wantsTrick && winners.isNotEmpty() -> winners.minBy { strengthOf(it) }
+            // Spite: stop somebody from landing the bid they need.
+            spoiling && winners.isNotEmpty() && victimNeedsOne(state) -> winners.minBy { strengthOf(it) }
             // Cannot take it, or do not want it: throw the least useful card.
-            losers.isNotEmpty() -> PlayCard(losers.minBy { strengthOf(it) })
+            losers.isNotEmpty() -> losers.minBy { strengthOf(it) }
             // Everything we hold wins, and we did not want the trick. Take it
             // with the weakest winner so the good cards stay for later.
-            else -> PlayCard(cards.minBy { strengthOf(it) })
+            else -> cards.minBy { strengthOf(it) }
         }
     }
 
+    /** Whether whoever is winning the trick right now needs exactly this trick to make their bid. */
+    private fun victimNeedsOne(state: WizardState): Boolean {
+        val ledSuit = ledSuitOf(state.trick)
+        val leading = state.trick
+            .withIndex()
+            .maxByOrNull { (index, played) -> trickStrength(played.card, index, state.trump, ledSuit) }
+            ?: return false
+        val victim = leading.value.seat
+        return (state.bids[victim] ?: return false) - state.tricksWon[victim] == 1
+    }
+
+    /**
+     * The strong player's choice. It keeps track of which cards are gone to
+     * judge how likely each of its own is to win, spends sure winners when it
+     * needs tricks, and sheds its most dangerous cards onto tricks it will
+     * lose anyway when it does not.
+     */
+    private fun hardPlay(
+        state: WizardState,
+        seat: Int,
+        cards: List<Card>,
+        seen: Set<Card>,
+        wantsTrick: Boolean,
+        spoiling: Boolean,
+        stillNeeded: Int,
+        tricksLeft: Int,
+    ): Card {
+        val hand = state.hands[seat]
+        val unseen = DECK.filter { it != state.trumpCard && it !in seen && it !in hand }
+        val oppCards = state.handCounts.sum() - hand.size
+        val q = if (unseen.isEmpty()) 0.0 else (oppCards.toDouble() / unseen.size).coerceIn(0.0, 1.0)
+        val trump = state.trump
+        fun pWin(card: Card): Double = winProb(card, unseen, trump, q, tricksLeft)
+
+        if (state.trick.isEmpty()) {
+            if (wantsTrick) {
+                val scored = cards.map { it to pWin(it) }
+                val bestOverall = scored.maxBy { it.second }
+                // With tricks to spare, save the wizard for when it is needed.
+                if (tricksLeft > stillNeeded) {
+                    val bestPlain = scored.filter { !isWizardCard(it.first) }.maxByOrNull { it.second }
+                    if (bestPlain != null && bestPlain.second >= 0.6) return bestPlain.first
+                }
+                return bestOverall.first
+            }
+            // Ducking: lead whatever is least likely to win, a jester best of all.
+            return cards.minWith(compareBy<Card>({ pWin(it) }, { it.rank.order }))
+        }
+
+        val ledSuit = ledSuitOf(state.trick)
+        val order = state.trick.size
+        val remaining = state.options.playerCount - order - 1
+        val bestOnTable = state.trick
+            .withIndex()
+            .maxOf { (index, played) -> trickStrength(played.card, index, trump, ledSuit) }
+        val strengthOf = { card: Card -> trickStrength(card, order, trump, ledSuit) }
+        val winners = cards.filter { strengthOf(it) > bestOnTable }
+        val losers = cards.filter { strengthOf(it) <= bestOnTable }
+
+        fun sure(card: Card): Boolean =
+            remaining == 0 || unseen.none { trickStrength(it, order + 1, trump, ledSuit) > strengthOf(card) }
+
+        if (wantsTrick) {
+            if (winners.isNotEmpty()) {
+                val certain = winners.filter { sure(it) }
+                return (certain.ifEmpty { winners }).minBy { strengthOf(it) }
+            }
+            // Cannot take this one: keep the strong cards for a trick that can be won.
+            return losers.minBy { strengthOf(it) }
+        }
+        if (spoiling && winners.isNotEmpty() && victimNeedsOne(state)) {
+            return winners.minBy { strengthOf(it) }
+        }
+        if (losers.isNotEmpty()) {
+            // Unload the card that would be hardest to lose later, but keep the
+            // jester: it is the one card that can never win.
+            val nonJester = losers.filter { !isJester(it) }
+            return (nonJester.ifEmpty { losers }).maxBy { strengthOf(it) }
+        }
+        return cards.minBy { strengthOf(it) }
+    }
+
     private fun chooseLead(cards: List<Card>, trump: Suit?, wantsTrick: Boolean): Card {
         if (wantsTrick) {
             // A led wizard is an unloseable trick.

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

@@ -1,6 +1,11 @@
 package org.prolibertate.games.game.yahtzee
 
+import org.prolibertate.games.game.engine.AiLevel
+import org.prolibertate.games.game.engine.AiProfile
+import org.prolibertate.games.game.engine.AiProfiles
 import org.prolibertate.games.game.engine.GameAi
+import kotlin.math.exp
+import kotlin.math.sqrt
 
 /**
  * Plays the dice by eye rather than by arithmetic.
@@ -10,33 +15,53 @@ import org.prolibertate.games.game.engine.GameAi
  * enumerated the thirty-two subsets and applied them would be reading the roll
  * before making it — beating the player by seeing the future rather than by
  * playing well. Everything below decides from the dice already on the table.
+ *
+ * Per seat, from [profiles]: Easy sometimes holds a poor set of dice and
+ * sometimes writes a lesser box than the best on offer. Hard works out, for
+ * every way of holding dice, the *expected* value of what could be thrown
+ * (averaging over all outcomes, never over the roll that will actually come),
+ * valuing each box by what it scores less what that box is usually worth, with
+ * the upper-section bonus tracked. Boldness chases the bonus and big combos
+ * and rolls on with slimmer odds; caution takes a sure score sooner.
  */
-object YahtzeeAi : GameAi<YahtzeeState, YahtzeeMove> {
+class YahtzeeAi(private val profiles: AiProfiles = AiProfiles.DEFAULT) :
+    GameAi<YahtzeeState, YahtzeeMove> {
 
     override fun chooseMove(state: YahtzeeState, seat: Int, legal: List<YahtzeeMove>): YahtzeeMove {
         require(legal.isNotEmpty()) { "No legal move for seat $seat" }
+        val profile = profiles.of(seat)
         val rolls = legal.filterIsInstance<RollDice>()
         val writes = legal.filterIsInstance<ScoreIn>()
 
         // Nothing on the table yet, so there is only one thing to do.
         if (!state.hasRolled) return rolls.firstOrNull() ?: writes.first()
+        if (profile.level == AiLevel.HARD && writes.isNotEmpty()) {
+            return chooseExpected(state, seat, rolls, writes, profile)
+        }
 
-        val best = writes.maxByOrNull { scoreOf(it.category, state.dice) }
+        val ranked = writes.sortedByDescending { scoreOf(it.category, state.dice) }
+        // Easy sometimes writes the second or third best box rather than the best.
+        val best = if (ranked.isEmpty()) null else profile.pick(ranked.take(EASY_BOXES))
         val bestScore = best?.let { scoreOf(it.category, state.dice) } ?: 0
 
         // A hand already worth taking, or no rolls left, ends the turn.
         if (rolls.isEmpty()) return best ?: writes.first()
-        if (bestScore >= WORTH_KEEPING) return best!!
+        if (bestScore >= profile.bolder(WORTH_KEEPING.toDouble(), 4.0)) return best!!
 
-        val keep = whatToKeep(state.dice).toSet()
+        val keep = if (profile.slips()) poorKeep(state.dice) else whatToKeep(state.dice).toSet()
         return rolls.firstOrNull { it.keep == keep } ?: rolls.first()
     }
 
-    /**
-     * Good enough to stop throwing. Set at a full house, which is the point
-     * where a hand is worth more than an average reroll of it.
-     */
-    private const val WORTH_KEEPING = 25
+    /** What a distracted player holds: the high dice, or the pair they notice second. */
+    private fun poorKeep(dice: List<Int>): Set<Int> {
+        val counts = countsOf(dice)
+        val second = counts.entries
+            .sortedWith(compareByDescending<Map.Entry<Int, Int>> { it.value }.thenBy { it.key })
+            .drop(1)
+            .firstOrNull { it.value >= 2 }
+        if (second != null) return dice.indices.filter { dice[it] == second.key }.toSet()
+        return dice.indices.filter { dice[it] >= 4 }.toSet()
+    }
 
     /**
      * What to hold on to: a run if one is nearly there, otherwise the face there
@@ -82,4 +107,213 @@ object YahtzeeAi : GameAi<YahtzeeState, YahtzeeMove> {
             face in wanted && taken.add(face)
         }
     }
+
+    // -- Hard: expected values ------------------------------------------------
+
+    /**
+     * Values every box as what it scores now less what it is normally worth, so
+     * that writing a zero in Ones costs little and writing one in Yahtzee costs a
+     * lot, then looks two throws ahead by averaging over every possible outcome
+     * of every way of holding dice.
+     */
+    private fun chooseExpected(
+        state: YahtzeeState,
+        seat: Int,
+        rolls: List<RollDice>,
+        writes: List<ScoreIn>,
+        profile: AiProfile,
+    ): YahtzeeMove {
+        val valuation = Valuation(state, seat, profile.style.boldness)
+        val dice = state.dice
+        val stop = writes.maxByOrNull { valuation.gain(it.category, dice) } ?: writes.first()
+        if (rolls.isEmpty()) return stop
+        val stopValue = valuation.gain(stop.category, dice)
+
+        // terminal[i]: best write for the i-th multiset of dice with no throws left.
+        val terminal = DoubleArray(DiceTables.multisets.size) { i ->
+            val faces = DiceTables.facesOf(i)
+            writes.maxOf { valuation.gain(it.category, faces) }
+        }
+        // Each throw still to come after the next one, worked backwards.
+        var next = terminal
+        repeat(state.rollsLeft - 1) {
+            val previous = next
+            next = DoubleArray(terminal.size) { i ->
+                maxOf(terminal[i], bestKeep(i, previous).second)
+            }
+        }
+        val here = DiceTables.indexOf(countVector(dice))
+        val (keepCounts, expected) = bestKeep(here, next)
+        val margin = -profile.style.boldness
+        if (expected <= stopValue + margin) return stop
+
+        val remaining = keepCounts.copyOf()
+        val keep = dice.indices.filter { position ->
+            val face = dice[position] - 1
+            if (remaining[face] > 0) {
+                remaining[face]--
+                true
+            } else {
+                false
+            }
+        }.toSet()
+        return rolls.firstOrNull { it.keep == keep } ?: stop
+    }
+
+    /** The best set of dice to hold from multiset [index], and what throwing the rest is worth. */
+    private fun bestKeep(index: Int, after: DoubleArray): Pair<IntArray, Double> {
+        var bestKeep = DiceTables.keepsOf(index).first()
+        var best = Double.NEGATIVE_INFINITY
+        for (keep in DiceTables.keepsOf(index)) {
+            val thrown = DICE_COUNT - keep.sum()
+            var key = 0
+            for (face in 0 until 6) key += keep[face] * DiceTables.POWERS[face]
+            var total = 0.0
+            for (outcome in DiceTables.rerolls[thrown]) {
+                total += outcome.probability * after[DiceTables.indexOfKey[key + outcome.key]]
+            }
+            if (total > best + 1e-9) {
+                best = total
+                bestKeep = keep
+            }
+        }
+        return bestKeep to best
+    }
+
+    private fun countVector(dice: List<Int>): IntArray {
+        val counts = IntArray(6)
+        dice.forEach { counts[it - 1]++ }
+        return counts
+    }
+
+    /** What a box is worth to this card right now, in points relative to its usual yield. */
+    private class Valuation(state: YahtzeeState, seat: Int, private val boldness: Double) {
+        private val card = state.cards[seat]
+        private val yahtzeeBonus = state.options.yahtzeeBonus && card[YahtzeeCategory.YAHTZEE] == YAHTZEE_SCORE
+        private val openUpper = YahtzeeCategory.entries.filter {
+            it.section == YahtzeeSection.UPPER && !card.isFilled(it)
+        }
+        private val secured = card.upperSubtotal >= UPPER_BONUS_AT
+        private val diff = YahtzeeCategory.entries
+            .filter { it.section == YahtzeeSection.UPPER && card.isFilled(it) }
+            .sumOf { (card[it] ?: 0) - 3 * it.face!! }
+        private val bonusValue = UPPER_BONUS * (1.0 + 0.4 * boldness)
+
+        fun gain(category: YahtzeeCategory, dice: List<Int>): Double {
+            val score = scoreOf(category, dice)
+            var value = score - TYPICAL[category.ordinal]
+            if (category.section == YahtzeeSection.UPPER && !secured) {
+                val face = category.face!!
+                val after = if (card.upperSubtotal + score >= UPPER_BONUS_AT) {
+                    1.0
+                } else {
+                    chance(diff + score - 3 * face, openUpper - category)
+                }
+                value += bonusValue * (after - chance(diff, openUpper))
+            }
+            // The big combinations: a bold seat values them a little more.
+            if (score > 0 && (category == YahtzeeCategory.LARGE_STRAIGHT ||
+                    category == YahtzeeCategory.YAHTZEE || category == YahtzeeCategory.FOUR_OF_A_KIND)
+            ) {
+                value += boldness * 2.0
+            }
+            if (yahtzeeBonus && isYahtzee(dice)) value += YAHTZEE_BONUS
+            return value
+        }
+
+        /** Likelihood the upper section still reaches the bonus from [difference] with [open] to fill. */
+        private fun chance(difference: Int, open: List<YahtzeeCategory>): Double {
+            if (open.isEmpty()) return if (difference >= 0) 1.0 else 0.0
+            val expected = open.sumOf { TYPICAL[it.ordinal] - 3 * it.face!! }
+            val spread = 2.2 * sqrt(open.size.toDouble()) + 0.3
+            return 1.0 / (1.0 + exp(-(difference + expected + 1.5) / spread))
+        }
+    }
+
+    /** Every multiset of five dice and every throw of n dice, worked out once. */
+    private object DiceTables {
+        class Outcome(val key: Int, val probability: Double)
+
+        val POWERS = intArrayOf(1, 6, 36, 216, 1296, 7776)
+        val indexOfKey = IntArray(46656) { -1 }
+        val multisets: List<IntArray> = vectors(DICE_COUNT)
+        val rerolls: Array<List<Outcome>> = Array(DICE_COUNT + 1) { n ->
+            val factorial = IntArray(6) { f -> (1..f).fold(1) { a, b -> a * b } }
+            val total = Math.pow(6.0, n.toDouble())
+            vectors(n).map { counts ->
+                val ways = (1..n).fold(1) { a, b -> a * b } / counts.fold(1) { a, c -> a * factorial[c] }
+                Outcome(keyOf(counts), ways / total)
+            }
+        }
+        private val keeps: Array<List<IntArray>?> = arrayOfNulls(multisets.size)
+
+        init {
+            multisets.forEachIndexed { i, counts -> indexOfKey[keyOf(counts)] = i }
+        }
+
+        fun indexOf(counts: IntArray): Int = indexOfKey[keyOf(counts)]
+
+        fun facesOf(index: Int): List<Int> {
+            val faces = ArrayList<Int>(DICE_COUNT)
+            multisets[index].forEachIndexed { f, c -> repeat(c) { faces += f + 1 } }
+            return faces
+        }
+
+        /** Every distinct set of dice that can be held back from multiset [index]. */
+        fun keepsOf(index: Int): List<IntArray> {
+            keeps[index]?.let { return it }
+            val counts = multisets[index]
+            var all = listOf(IntArray(6))
+            for (face in 0 until 6) {
+                all = all.flatMap { partial ->
+                    (0..counts[face]).map { n -> partial.copyOf().also { it[face] = n } }
+                }
+            }
+            keeps[index] = all
+            return all
+        }
+
+        private fun keyOf(counts: IntArray): Int {
+            var key = 0
+            for (face in 0 until 6) key += counts[face] * POWERS[face]
+            return key
+        }
+
+        /** Every way to split [size] dice over six faces. */
+        private fun vectors(size: Int): List<IntArray> {
+            val out = ArrayList<IntArray>()
+            fun build(face: Int, left: Int, current: IntArray) {
+                if (face == 5) {
+                    current[5] = left
+                    out += current.copyOf()
+                    return
+                }
+                for (n in 0..left) {
+                    current[face] = n
+                    build(face + 1, left - n, current)
+                }
+            }
+            build(0, size, IntArray(6))
+            return out
+        }
+    }
+
+    private companion object {
+        /**
+         * Good enough to stop throwing. Set at a full house, which is the point
+         * where a hand is worth more than an average reroll of it.
+         */
+        const val WORTH_KEEPING = 25
+
+        /** How many of the best boxes Easy chooses among when it writes a score. */
+        const val EASY_BOXES = 3
+
+        /**
+         * What each box yields on average under strong play, in the order of
+         * [YahtzeeCategory]: the cost of spending it.
+         */
+        val TYPICAL = doubleArrayOf(
+            2.11, 5.28, 8.57, 12.16, 15.69, 19.19, 21.66, 13.10, 22.59, 29.46, 32.71, 16.87, 22.01,
+        )
+    }
 }

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

@@ -8,6 +8,7 @@ import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.StateFlow
 import kotlinx.coroutines.flow.asStateFlow
 import kotlinx.coroutines.launch
+import org.prolibertate.games.game.engine.AiDifficulty
 import org.prolibertate.games.game.engine.PlayerKind
 import org.prolibertate.games.game.engine.PlayerSlot
 import org.prolibertate.games.game.engine.TableConfig
@@ -33,6 +34,7 @@ class LobbyController(
         val connected: Boolean = false,
         val gameId: String? = null,
         val optionsJson: String = "{}",
+        val aiDifficulty: AiDifficulty = AiDifficulty.MEDIUM,
         val hostName: String = "",
         val seats: List<PlayerSlot> = emptyList(),
         val discovered: List<DiscoveredHost> = emptyList(),
@@ -88,6 +90,7 @@ class LobbyController(
         hostName: String,
         seatCount: Int,
         teamOf: (Int) -> Int,
+        aiDifficulty: AiDifficulty = AiDifficulty.MEDIUM,
     ) {
         stop()
         val seats = (0 until seatCount).map { seat ->
@@ -102,6 +105,7 @@ class LobbyController(
             hosting = true,
             gameId = gameId,
             optionsJson = optionsJson,
+            aiDifficulty = aiDifficulty,
             hostName = hostName,
             seats = seats,
             message = "Waiting for players…",
@@ -237,6 +241,7 @@ class LobbyController(
             seats = current.seats,
             optionsJson = current.optionsJson,
             seed = seed,
+            aiDifficulty = current.aiDifficulty,
         )
         scope.launch { connections.values.forEach { it.send(StartGame(config)) } }
         _state.value = current.copy(started = config)

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

@@ -57,6 +57,7 @@ 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.AiDifficulty
 import org.prolibertate.games.game.engine.SavedGameStore
 import org.prolibertate.games.game.engine.SavedMatch
 
@@ -92,7 +93,12 @@ sealed interface Route {
     /** Every saved game, to carry on from or delete. */
     data object Resume : Route
     data class Setup(val gameId: String) : Route
-    data class Lobby(val gameId: String, val optionsJson: String, val hosting: Boolean) : Route
+    data class Lobby(
+        val gameId: String,
+        val optionsJson: String,
+        val hosting: Boolean,
+        val aiDifficulty: AiDifficulty = AiDifficulty.MEDIUM,
+    ) : Route
     data class Play(
         val gameId: String,
         val config: TableConfig,
@@ -250,8 +256,8 @@ private fun AppContent(
                 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))
+                onHostOnline = { optionsJson, aiDifficulty ->
+                    push(Route.Lobby(route.gameId, optionsJson, hosting = true, aiDifficulty = aiDifficulty))
                 },
                 saved = saved,
                 onResume = { match ->

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

@@ -30,15 +30,13 @@ import kotlinx.serialization.encodeToString
 import kotlinx.serialization.json.Json
 import org.prolibertate.games.game.GameCatalog
 import org.prolibertate.games.game.GameDescriptor
+import org.prolibertate.games.game.engine.AiDifficulty
 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
-import org.prolibertate.games.game.checkers.CheckersLevel
 import org.prolibertate.games.game.checkers.CheckersOptions
-import org.prolibertate.games.game.chess.ChessLevel
 import org.prolibertate.games.game.chess.ChessOptions
 import org.prolibertate.games.game.crazyeights.CrazyEightsOptions
 import org.prolibertate.games.game.cribbage.CribbageOptions
@@ -56,15 +54,14 @@ import org.prolibertate.games.game.pegsolitaire.PegBoard
 import org.prolibertate.games.game.pegsolitaire.PegGoal
 import org.prolibertate.games.game.pegsolitaire.PegSolitaireOptions
 import org.prolibertate.games.game.kaiser.KaiserOptions
-import org.prolibertate.games.game.mastermind.MastermindLevel
 import org.prolibertate.games.game.mastermind.MastermindOptions
-import org.prolibertate.games.game.morris.MorrisLevel
 import org.prolibertate.games.game.morris.MorrisOptions
-import org.prolibertate.games.game.pirates.PiratesLevel
 import org.prolibertate.games.game.pirates.PiratesOptions
 import org.prolibertate.games.game.president.PresidentOptions
 import org.prolibertate.games.game.catan.CatanOptions
-import org.prolibertate.games.game.catan.CatanRuleSet
+import org.prolibertate.games.game.catan.CatanExpansion
+import org.prolibertate.games.game.catan.SeaScenario
+import org.prolibertate.games.game.catan.BaseScenario
 import org.prolibertate.games.game.sequence.SequenceOptions
 import org.prolibertate.games.game.tayu.TayuLevel
 import org.prolibertate.games.game.tayu.TayuOptions
@@ -88,7 +85,7 @@ fun GameSetupScreen(
     playerName: String,
     onBack: () -> Unit,
     onPlayOffline: (TableConfig, Int) -> Unit,
-    onHostOnline: (String) -> Unit,
+    onHostOnline: (String, AiDifficulty) -> Unit,
     /** A game of this kind left half-played, if there is one. */
     saved: SavedMatch? = null,
     onResume: (SavedMatch) -> Unit = {},
@@ -124,6 +121,7 @@ fun GameSetupScreen(
     // Pirates and Bulgars is not symmetrical, so which side you take is the
     // first thing about the game rather than a detail of it.
     var playPirates by remember { mutableStateOf(false) }
+    var aiDifficulty by remember { mutableStateOf(AiDifficulty.MEDIUM) }
 
     val optionsJson = when (descriptor.id) {
         GameCatalog.EUCHRE -> setupJson.encodeToString(euchre)
@@ -243,6 +241,22 @@ fun GameSetupScreen(
                 style = MaterialTheme.typography.bodySmall,
             )
 
+            if (!solo) {
+                ChipRow(
+                    label = "Computer difficulty",
+                    values = AiDifficulty.entries.toList(),
+                    selected = aiDifficulty,
+                    display = { it.label },
+                    onSelect = { aiDifficulty = it },
+                )
+                if (aiDifficulty == AiDifficulty.MIXED) {
+                    Text(
+                        "Each computer player gets its own level.",
+                        style = MaterialTheme.typography.bodySmall,
+                    )
+                }
+            }
+
             // Two games let the local player pick a seat rather than always
             // taking the first one: chess by colour, and Pirates and Bulgars by
             // which side of a very lopsided fight they fancy.
@@ -259,13 +273,13 @@ fun GameSetupScreen(
             }
             PrimaryAction(text = if (solo) "Play" else "Play against the computer") {
                 onPlayOffline(
-                    offlineConfig(descriptor.id, optionsJson, seatCount, playerName, localSeat),
+                    offlineConfig(descriptor.id, optionsJson, seatCount, playerName, localSeat, aiDifficulty),
                     localSeat,
                 )
             }
             if (!solo) {
                 PrimaryAction(text = "Host a game for others to join") {
-                    onHostOnline(optionsJson)
+                    onHostOnline(optionsJson, aiDifficulty)
                 }
             }
         }
@@ -279,6 +293,7 @@ private fun offlineConfig(
     seatCount: Int,
     playerName: String,
     localSeat: Int = 0,
+    aiDifficulty: AiDifficulty = AiDifficulty.MEDIUM,
 ): TableConfig = TableConfig(
     gameId = gameId,
     seats = (0 until seatCount).map { seat ->
@@ -292,6 +307,7 @@ private fun offlineConfig(
     optionsJson = optionsJson,
     // Seeded from the clock so consecutive games are not identical.
     seed = System.currentTimeMillis(),
+    aiDifficulty = aiDifficulty,
 )
 
 /**
@@ -359,47 +375,50 @@ fun teamForSeat(gameId: String, seat: Int, seatCount: Int): Int = when (gameId)
     else -> seat
 }
 
-/** The targets the setup screen offers for a Katan rule set. */
-internal fun catanPointsChoices(ruleSet: CatanRuleSet): List<Int> = when (ruleSet) {
-    // Five is a short game for trying things out; ten is the published target.
-    CatanRuleSet.BASE -> listOf(5, 8, 10, 12)
-    // Cities & Knights is played to thirteen, which is also why it runs longer.
-    CatanRuleSet.CITIES_AND_KNIGHTS -> listOf(8, 10, 13, 15)
+/** The targets the setup screen offers for a Katan game with [expansions] on. */
+internal fun catanPointsChoices(expansions: Set<CatanExpansion>): List<Int> = when {
+    // Both: Cities & Knights' long game plus the new-island points.
+    expansions.size > 1 -> listOf(10, 12, 14, 16)
     // Seafarers adds two points for each new island, so the target is higher.
-    CatanRuleSet.SEAFARERS -> listOf(8, 10, 12, 14)
+    CatanExpansion.SEAFARERS in expansions -> listOf(8, 10, 12, 14)
+    // Cities & Knights is played to thirteen, which is also why it runs longer.
+    CatanExpansion.CITIES_AND_KNIGHTS in expansions -> listOf(8, 10, 13, 15)
+    // Five is a short game for trying things out; ten is the published target.
+    else -> listOf(5, 8, 10, 12)
 }
 
-/** 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
+/** The published target for a game with [expansions] on. */
+internal fun catanDefaultPoints(expansions: Set<CatanExpansion>): Int = when {
+    expansions.size > 1 -> 14
+    CatanExpansion.SEAFARERS in expansions -> 12
+    CatanExpansion.CITIES_AND_KNIGHTS in expansions -> 13
+    else -> 10
 }
 
 /**
- * [options] switched to [ruleSet]. The target moves to the new rule set's own
+ * [options] with [expansion] switched on or off. The target moves to the new combination's own
  * default unless the one already chosen is on its menu too.
  */
-internal fun catanSwitchRules(options: CatanOptions, ruleSet: CatanRuleSet): CatanOptions =
-    options.copy(
-        ruleSet = ruleSet,
-        pointsToWin = options.pointsToWin.takeIf { it in catanPointsChoices(ruleSet) && it != catanDefaultPoints(options.ruleSet) }
-            ?: catanDefaultPoints(ruleSet),
+internal fun catanToggleExpansion(options: CatanOptions, expansion: CatanExpansion, on: Boolean): CatanOptions {
+    val expansions = if (on) options.expansions + expansion else options.expansions - expansion
+    return options.copy(
+        expansions = expansions,
+        pointsToWin = options.pointsToWin.takeIf {
+            it in catanPointsChoices(expansions) && it != catanDefaultPoints(options.expansions)
+        } ?: catanDefaultPoints(expansions),
     )
-
-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) {
-    CatanRuleSet.BASE ->
-        "Settle the island, trade, and play development cards. Longest Road and Largest Army score."
-    CatanRuleSet.CITIES_AND_KNIGHTS ->
+private fun catanExpansionName(expansion: CatanExpansion): String = when (expansion) {
+    CatanExpansion.CITIES_AND_KNIGHTS -> "Cities & Knights"
+    CatanExpansion.SEAFARERS -> "Seafarers"
+}
+
+private fun catanExpansionBlurb(expansion: CatanExpansion): String = when (expansion) {
+    CatanExpansion.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 ->
+    CatanExpansion.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."
 }
@@ -407,14 +426,33 @@ private fun catanRuleSetBlurb(ruleSet: CatanRuleSet): String = when (ruleSet) {
 @Composable
 private fun CatanOptionsEditor(options: CatanOptions, onChange: (CatanOptions) -> Unit) {
     Column(verticalArrangement = Arrangement.spacedBy(8.dp)) {
-        ChipRow(
-            label = "Rules",
-            values = CatanRuleSet.entries,
-            selected = options.ruleSet,
-            display = ::catanRuleSetName,
-            onSelect = { onChange(catanSwitchRules(options, it)) },
-        )
-        Text(catanRuleSetBlurb(options.ruleSet), style = MaterialTheme.typography.bodySmall)
+        CatanExpansion.entries.forEach { expansion ->
+            ToggleRow(
+                title = catanExpansionName(expansion),
+                subtitle = catanExpansionBlurb(expansion),
+                checked = expansion in options.expansions,
+                onChange = { onChange(catanToggleExpansion(options, expansion, it)) },
+            )
+        }
+        if (options.seafarers) {
+            ChipRow(
+                label = "Map",
+                values = SeaScenario.entries,
+                selected = options.scenario,
+                display = { it.title },
+                onSelect = { onChange(options.copy(scenario = it)) },
+            )
+            Text(options.scenario.blurb, style = MaterialTheme.typography.bodySmall)
+        } else {
+            ChipRow(
+                label = "Island",
+                values = BaseScenario.entries,
+                selected = options.baseScenario,
+                display = { it.title },
+                onSelect = { onChange(options.copy(baseScenario = it)) },
+            )
+            Text(options.baseScenario.blurb, style = MaterialTheme.typography.bodySmall)
+        }
         ChipRow(
             label = "Players",
             values = listOf(3, 4),
@@ -424,7 +462,7 @@ private fun CatanOptionsEditor(options: CatanOptions, onChange: (CatanOptions) -
         )
         ChipRow(
             label = "Game to",
-            values = catanPointsChoices(options.ruleSet),
+            values = catanPointsChoices(options.expansions),
             selected = options.pointsToWin,
             display = { "$it points" },
             onSelect = { onChange(options.copy(pointsToWin = it)) },
@@ -765,13 +803,6 @@ private fun ChessOptionsEditor(
             display = { if (it) "White" else "Black" },
             onSelect = onColour,
         )
-        ChipRow(
-            label = "Opponent",
-            values = ChessLevel.entries.toList(),
-            selected = options.level,
-            display = { it.label },
-            onSelect = { onChange(options.copy(level = it)) },
-        )
         ToggleRow(
             title = "Fifty-move rule",
             subtitle = "Fifty moves each with no capture and no pawn move is a draw",
@@ -795,13 +826,6 @@ private fun ChessOptionsEditor(
 @Composable
 private fun CheckersOptionsEditor(options: CheckersOptions, onChange: (CheckersOptions) -> Unit) {
     Column(verticalArrangement = Arrangement.spacedBy(8.dp)) {
-        ChipRow(
-            label = "Opponent",
-            values = CheckersLevel.entries.toList(),
-            selected = options.level,
-            display = { it.label },
-            onSelect = { onChange(options.copy(level = it)) },
-        )
         ToggleRow(
             title = "Flying kings",
             subtitle = "A king slides the length of a diagonal and takes from a distance, " +
@@ -836,13 +860,6 @@ private fun BackgammonOptionsEditor(
     onChange: (BackgammonOptions) -> Unit,
 ) {
     Column(verticalArrangement = Arrangement.spacedBy(8.dp)) {
-        ChipRow(
-            label = "Opponent",
-            values = BackgammonLevel.entries.toList(),
-            selected = options.level,
-            display = { it.label },
-            onSelect = { onChange(options.copy(level = it)) },
-        )
         ToggleRow(
             title = "Count gammons",
             subtitle = "A loser who bore nothing off has lost double, and one still on the " +
@@ -864,13 +881,6 @@ private fun MastermindOptionsEditor(
     onChange: (MastermindOptions) -> Unit,
 ) {
     Column(verticalArrangement = Arrangement.spacedBy(8.dp)) {
-        ChipRow(
-            label = "Opponent",
-            values = MastermindLevel.entries.toList(),
-            selected = options.level,
-            display = { it.label },
-            onSelect = { onChange(options.copy(level = it)) },
-        )
         ChipRow(
             label = "Colours",
             values = listOf(6, 8),
@@ -935,13 +945,6 @@ private fun PiratesOptionsEditor(
             display = { if (it) "the two pirates" else "the twenty-four Bulgars" },
             onSelect = onSide,
         )
-        ChipRow(
-            label = "Opponent",
-            values = PiratesLevel.entries.toList(),
-            selected = options.level,
-            display = { it.label },
-            onSelect = { onChange(options.copy(level = it)) },
-        )
         ToggleRow(
             title = "A pirate who can take must take",
             subtitle = "The rule that huffing exists to enforce, applied directly",
@@ -967,13 +970,6 @@ private fun PiratesOptionsEditor(
 @Composable
 private fun MorrisOptionsEditor(options: MorrisOptions, onChange: (MorrisOptions) -> Unit) {
     Column(verticalArrangement = Arrangement.spacedBy(8.dp)) {
-        ChipRow(
-            label = "Opponent",
-            values = MorrisLevel.entries.toList(),
-            selected = options.level,
-            display = { it.label },
-            onSelect = { onChange(options.copy(level = it)) },
-        )
         ChipRow(
             label = "Pieces each",
             values = listOf(3, 6, 9),

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

@@ -60,6 +60,7 @@ fun LobbyScreen(
                 hostName = playerName,
                 seatCount = seatCount,
                 teamOf = { seat -> teamForSeat(route.gameId, seat, seatCount) },
+                aiDifficulty = route.aiDifficulty,
             )
         } else {
             env.lobby.startDiscovery()

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

@@ -120,6 +120,7 @@ import org.prolibertate.games.game.wizard.WizardRules
 import org.prolibertate.games.game.wizard.WizardState
 import org.prolibertate.games.net.MatchController
 import org.prolibertate.games.net.MatchSaver
+import org.prolibertate.games.game.engine.AiProfiles
 import org.prolibertate.games.game.engine.PlayerKind
 import org.prolibertate.games.settings.Settings
 import org.prolibertate.games.ui.game.BackgammonScreen
@@ -174,7 +175,7 @@ fun PlayScreen(
                 val controller = remember(route) {
                     MatchController<EuchreState, EuchreMove>(
                         rules = EuchreRules,
-                        ai = EuchreAi(),
+                        ai = EuchreAi(AiProfiles(route.config)),
                         config = route.config,
                         scope = scope,
                         role = role,
@@ -213,7 +214,7 @@ fun PlayScreen(
                 val controller = remember(route) {
                     MatchController<SequenceState, SequenceMove>(
                         rules = SequenceRules,
-                        ai = SequenceAi(),
+                        ai = SequenceAi(AiProfiles(route.config)),
                         config = route.config,
                         scope = scope,
                         role = role,
@@ -230,7 +231,7 @@ fun PlayScreen(
                 val controller = remember(route) {
                     MatchController<PresidentState, PresidentMove>(
                         rules = PresidentRules,
-                        ai = PresidentAi(),
+                        ai = PresidentAi(AiProfiles(route.config)),
                         config = route.config,
                         scope = scope,
                         role = role,
@@ -254,7 +255,7 @@ fun PlayScreen(
                 val controller = remember(route) {
                     MatchController<GolfState, GolfMove>(
                         rules = GolfRules,
-                        ai = GolfAi(),
+                        ai = GolfAi(AiProfiles(route.config)),
                         config = route.config,
                         scope = scope,
                         role = role,
@@ -276,7 +277,7 @@ fun PlayScreen(
                 val controller = remember(route) {
                     MatchController<KaiserState, KaiserMove>(
                         rules = KaiserRules,
-                        ai = KaiserAi(),
+                        ai = KaiserAi(AiProfiles(route.config)),
                         config = route.config,
                         scope = scope,
                         role = role,
@@ -312,7 +313,7 @@ fun PlayScreen(
                 val controller = remember(route) {
                     MatchController<WizardState, WizardMove>(
                         rules = WizardRules,
-                        ai = WizardAi(),
+                        ai = WizardAi(AiProfiles(route.config)),
                         config = route.config,
                         scope = scope,
                         role = role,
@@ -350,7 +351,7 @@ fun PlayScreen(
                 val controller = remember(route) {
                     MatchController<CrazyEightsState, CrazyEightsMove>(
                         rules = CrazyEightsRules,
-                        ai = CrazyEightsAi(),
+                        ai = CrazyEightsAi(AiProfiles(route.config)),
                         config = route.config,
                         scope = scope,
                         role = role,
@@ -377,7 +378,7 @@ fun PlayScreen(
                 val controller = remember(route) {
                     MatchController<CribbageState, CribbageMove>(
                         rules = CribbageRules,
-                        ai = CribbageAi(),
+                        ai = CribbageAi(AiProfiles(route.config)),
                         config = route.config,
                         scope = scope,
                         role = role,
@@ -406,7 +407,7 @@ fun PlayScreen(
                         rules = TayuRules,
                         // As with chess, the strength is part of the table's own
                         // options, so this does not have to decode anything.
-                        ai = TayuAi(),
+                        ai = TayuAi(AiProfiles(route.config)),
                         config = route.config,
                         scope = scope,
                         role = role,
@@ -423,7 +424,7 @@ fun PlayScreen(
                 val controller = remember(route) {
                     MatchController<CheckersState, CheckersMove>(
                         rules = CheckersRules,
-                        ai = CheckersAi(),
+                        ai = CheckersAi(AiProfiles(route.config)),
                         config = route.config,
                         scope = scope,
                         role = role,
@@ -440,7 +441,7 @@ fun PlayScreen(
                 val controller = remember(route) {
                     MatchController<BackgammonState, BackgammonMove>(
                         rules = BackgammonRules,
-                        ai = BackgammonAi(),
+                        ai = BackgammonAi(AiProfiles(route.config)),
                         config = route.config,
                         scope = scope,
                         role = role,
@@ -459,7 +460,7 @@ fun PlayScreen(
                 val controller = remember(route) {
                     MatchController<MastermindState, MastermindMove>(
                         rules = MastermindRules,
-                        ai = MastermindAi(),
+                        ai = MastermindAi(AiProfiles(route.config)),
                         config = route.config,
                         scope = scope,
                         role = role,
@@ -476,7 +477,7 @@ fun PlayScreen(
                 val controller = remember(route) {
                     MatchController<PiratesState, PiratesMove>(
                         rules = PiratesRules,
-                        ai = PiratesAi(),
+                        ai = PiratesAi(AiProfiles(route.config)),
                         config = route.config,
                         scope = scope,
                         role = role,
@@ -493,7 +494,7 @@ fun PlayScreen(
                 val controller = remember(route) {
                     MatchController<HeartsState, HeartsMove>(
                         rules = HeartsRules,
-                        ai = HeartsAi,
+                        ai = HeartsAi(AiProfiles(route.config)),
                         config = route.config,
                         scope = scope,
                         role = role,
@@ -582,7 +583,7 @@ fun PlayScreen(
                 val controller = remember(route) {
                     MatchController<YahtzeeState, YahtzeeMove>(
                         rules = YahtzeeRules,
-                        ai = YahtzeeAi,
+                        ai = YahtzeeAi(AiProfiles(route.config)),
                         config = route.config,
                         scope = scope,
                         role = role,
@@ -684,7 +685,7 @@ fun PlayScreen(
                         rules = MorrisRules,
                         // As with chess, the strength is part of the table's own
                         // options, so this does not have to decode anything.
-                        ai = MorrisAi(),
+                        ai = MorrisAi(AiProfiles(route.config)),
                         config = route.config,
                         scope = scope,
                         role = role,
@@ -705,7 +706,7 @@ fun PlayScreen(
                         rules = ChessRules,
                         // Strength comes from the table's own options, so the setup
                         // screen sets it without this having to decode anything.
-                        ai = ChessAi(),
+                        ai = ChessAi(AiProfiles(route.config)),
                         config = route.config,
                         scope = scope,
                         role = role,
@@ -724,7 +725,7 @@ fun PlayScreen(
                 val controller = remember(route) {
                     MatchController<CatanState, CatanMove>(
                         rules = CatanRules,
-                        ai = CatanAi(),
+                        ai = CatanAi(AiProfiles(route.config)),
                         config = route.config,
                         scope = scope,
                         role = role,

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

@@ -33,7 +33,9 @@ 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.SeaRules
 import org.prolibertate.games.game.catan.Terrain
+import org.prolibertate.games.game.catan.TribeChip
 
 /**
  * The island, drawn and tappable.
@@ -156,6 +158,39 @@ private fun DrawScope.drawHexes(
 
         val number = state.numbers[hex]
         if (number != 0) drawToken(number, centre, board, style, measurer)
+        if (state.terrains[hex] == Terrain.FOG) {
+            drawCentered(
+                measurer = measurer,
+                text = "?",
+                at = centre,
+                fontPx = board.radius * 0.9f,
+                color = style.hexEdge.copy(alpha = 0.7f),
+                weight = FontWeight.Bold,
+            )
+        }
+        val sea = state.sea
+        val note = when {
+            state.terrains[hex] == Terrain.VILLAGE && sea != null -> "${sea.villageCloth.getOrElse(hex) { 0 }} cloth"
+            sea != null && sea.canalNumbers.getOrElse(hex) { 0 } != 0 && state.terrains[hex] == Terrain.DESERT ->
+                "dug ${sea.canalUnits.getOrElse(hex) { 0 }}/${SeaRules.CANAL_TILE_UNITS}"
+            state.terrains[hex] == Terrain.FORTRESS && sea != null -> "fort ${sea.fortress.getOrElse(hex) { 0 }}"
+            else -> when (sea?.chips?.getOrNull(hex)) {
+                TribeChip.POINT -> "+1 VP"
+                TribeChip.HARBOUR -> "3:1"
+                TribeChip.GOLD -> "gold"
+                else -> null
+            }
+        }
+        if (note != null) {
+            drawCentered(
+                measurer = measurer,
+                text = note,
+                at = Pt(centre.x, centre.y + board.radius * 0.62f),
+                fontPx = board.radius * 0.26f,
+                color = style.tokenInk,
+                weight = FontWeight.Bold,
+            )
+        }
     }
 }
 

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

@@ -173,6 +173,9 @@ object CatanHudGlyphs {
         BuildKind.WALL -> "▦"
         BuildKind.KNIGHT -> "♞"
         BuildKind.SHIP -> "⛵"
+        BuildKind.RAID -> "⚔"
+        BuildKind.DIG -> "⛏"
+        BuildKind.WONDER -> "✦"
     }
 
     fun label(kind: BuildKind): String = when (kind) {
@@ -182,6 +185,9 @@ object CatanHudGlyphs {
         BuildKind.WALL -> CatanText.WALL
         BuildKind.KNIGHT -> CatanText.KNIGHT
         BuildKind.SHIP -> CatanText.SHIP
+        BuildKind.RAID -> CatanText.RAID
+        BuildKind.DIG -> CatanText.DIG
+        BuildKind.WONDER -> CatanText.WONDER
     }
 }
 
@@ -208,7 +214,7 @@ fun HudConfirmButtons(
 fun ZoomPanBox(
     modifier: Modifier = Modifier,
     minScale: Float = 1f,
-    maxScale: Float = 3f,
+    maxScale: Float = 6f,
     content: @Composable () -> Unit,
 ) {
     var scale by remember { mutableFloatStateOf(1f) }

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

@@ -6,7 +6,10 @@ 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.BuildWonder
+import org.prolibertate.games.game.catan.DigCanal
 import org.prolibertate.games.game.catan.MovePirate
+import org.prolibertate.games.game.catan.RaidFortress
 import org.prolibertate.games.game.catan.MoveShip
 import org.prolibertate.games.game.catan.Topology
 import org.prolibertate.games.game.catan.BuildSettlement
@@ -67,13 +70,38 @@ enum class BuildKind {
     ROAD, SETTLEMENT, CITY, WALL, KNIGHT,
 
     /** Seafarers: a ship, laid on a sea edge. */
-    SHIP;
+    SHIP,
+
+    /** Pirate Islands: raid a fortress; the target is the fortress hex. */
+    RAID,
+
+    /** Great Canal: dig a canal tile; the target is the tile. */
+    DIG,
+
+    /** Wonders of Catan: the next stage of the wonder, which needs no tap on the board. */
+    WONDER;
 
     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)
+
+        /** The kinds a table's build menu lists: the scenario's own raid or wonder follows the usual ones. */
+        fun of(state: CatanState): List<BuildKind> {
+            val sea = state.sea
+            val extras = buildList {
+                if (sea != null && sea.fortress.isNotEmpty()) add(RAID)
+                if (sea != null && sea.canalUnits.isNotEmpty()) add(DIG)
+                if (sea != null && sea.wonders.isNotEmpty()) add(WONDER)
+            }
+            val usual = when {
+                state.isCk -> entries.filter { it != SHIP || state.isSea } - listOf(RAID, DIG, WONDER)
+                state.isSea -> SEAFARERS
+                else -> BASE
+            }
+            return usual + extras
+        }
     }
 }
 
@@ -252,6 +280,13 @@ object CatanInteraction {
         return when (building) {
             BuildKind.ROAD -> BoardTargets(edges = roads)
             BuildKind.SHIP -> BoardTargets(edges = ships)
+            BuildKind.RAID -> BoardTargets(
+                hexes = legal.filterIsInstance<RaidFortress>().mapNotNull { state.topo.hexIndex[it.hex] }.toSet(),
+            )
+            BuildKind.DIG -> BoardTargets(
+                hexes = legal.filterIsInstance<DigCanal>().mapNotNull { state.topo.hexIndex[it.hex] }.toSet(),
+            )
+            BuildKind.WONDER -> BoardTargets()
             BuildKind.SETTLEMENT ->
                 BoardTargets(vertices = legal.filterIsInstance<BuildSettlement>().map { it.vertex }.toSet())
 
@@ -519,6 +554,7 @@ object CatanInteraction {
         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 }
+        legal.firstOrNull { (it is RaidFortress && it.hex == coord) || (it is DigCanal && it.hex == coord) }?.let { return TapOutcome.Submit(it) }
         return when {
             moves.isNotEmpty() -> if (moves.size == 1) {
                 TapOutcome.Submit(moves.first())
@@ -586,6 +622,9 @@ object CatanInteraction {
         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 RaidFortress }) add(BuildKind.RAID)
+        if (legal.any { it is DigCanal }) add(BuildKind.DIG)
+        if (legal.any { it is BuildWonder }) add(BuildKind.WONDER)
         if (legal.any { it is BuildWall }) add(BuildKind.WALL)
         if (legal.any { it is HireKnight }) add(BuildKind.KNIGHT)
     }

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

@@ -256,6 +256,8 @@ fun CatanPlayerCard(
                     if (at.seat == seat) add(if (compact) track.name.first().toString() else "${CatanText.track(track)} metropolis")
                 }
                 if (ck.merchant?.seat == seat) add("Merchant")
+                if (state.harbormaster == seat) add(if (compact) "Harbor" else "Harbormaster")
+                addAll(seaAwards(state, seat, compact))
             }
             CardLine(
                 text = ckAwards.joinToString(" · ").ifEmpty { BLANK },
@@ -280,6 +282,8 @@ fun CatanPlayerCard(
         val awards = buildList {
             if (state.longestRoadOwner == seat) add(if (compact) "Road" else "Longest road")
             if (state.largestArmyOwner == seat) add(if (compact) "Army" else "Largest army")
+            if (state.harbormaster == seat) add(if (compact) "Harbor" else "Harbormaster")
+            addAll(seaAwards(state, seat, compact))
         }
         // Always drawn, so the card does not grow when somebody takes an award.
         CardLine(
@@ -598,6 +602,9 @@ private fun buildLabel(kind: BuildKind): String = when (kind) {
     BuildKind.WALL -> CatanText.WALL
     BuildKind.KNIGHT -> CatanText.KNIGHT
     BuildKind.SHIP -> CatanText.SHIP
+    BuildKind.RAID -> CatanText.RAID
+    BuildKind.DIG -> CatanText.DIG
+    BuildKind.WONDER -> CatanText.WONDER
 }
 
 private fun buildCost(kind: BuildKind): String = when (kind) {
@@ -607,6 +614,9 @@ private fun buildCost(kind: BuildKind): String = when (kind) {
     BuildKind.WALL -> CatanText.WALL_COST
     BuildKind.KNIGHT -> CatanText.KNIGHT_COST
     BuildKind.SHIP -> CatanText.SHIP_COST_TEXT
+    BuildKind.RAID -> CatanText.RAID_COST
+    BuildKind.DIG -> CatanText.DIG_COST
+    BuildKind.WONDER -> CatanText.WONDER_COST
 }
 
 @Composable
@@ -634,3 +644,14 @@ fun CatanLog(state: CatanState, modifier: Modifier = Modifier) {
         }
     }
 }
+
+/** Seafarers scenario holdings worth a word on a player's card: cloth, and a tribe harbour. */
+private fun seaAwards(state: CatanState, seat: Int, compact: Boolean): List<String> {
+    val sea = state.sea ?: return emptyList()
+    return buildList {
+        if (sea.cloth.isNotEmpty()) add(if (compact) "${sea.cloth[seat]}c" else "Cloth ${sea.cloth[seat]}")
+        if (sea.canalDug.isNotEmpty()) add(if (compact) "${sea.canalDug[seat]}⛏" else "Dug ${sea.canalDug[seat]}")
+        if (sea.wonders.isNotEmpty()) add(if (compact) "W${sea.wonders[seat]}" else "Wonder ${sea.wonders[seat]}/4")
+        if (seat in sea.harbourSeats) add(if (compact) "3:1" else "Harbour 3:1")
+    }
+}

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

@@ -39,6 +39,7 @@ import androidx.compose.ui.text.style.TextOverflow
 import androidx.compose.ui.unit.dp
 import org.prolibertate.games.game.catan.AcceptTrade
 import org.prolibertate.games.game.catan.AqueductChore
+import org.prolibertate.games.game.catan.BuildWonder
 import org.prolibertate.games.game.catan.BuyDevCard
 import org.prolibertate.games.game.catan.CatanCk
 import org.prolibertate.games.game.catan.CatanMove
@@ -159,6 +160,14 @@ fun CatanScreen(
         }
     }
 
+    // A wonder stage needs no tap on the board: choosing it from the menu builds it.
+    LaunchedEffect(building) {
+        if (building == BuildKind.WONDER) {
+            legal.firstOrNull { it is BuildWonder }?.let { controller.submit(it) }
+            building = null
+        }
+    }
+
     val submit: (CatanMove) -> Unit = { move ->
         controller.submit(move)
         building = null
@@ -197,11 +206,7 @@ fun CatanScreen(
     val progressHand = CatanInteraction.progressHand(current, localSeat, legal)
     val playing = current.phase == CatanPhase.PLAYING && legal.isNotEmpty()
     val actions = CatanActions(
-        buildKinds = when {
-            current.isCk -> BuildKind.entries.filter { it != BuildKind.SHIP }
-            current.isSea -> BuildKind.SEAFARERS
-            else -> BuildKind.BASE
-        },
+        buildKinds = BuildKind.of(current),
         ck = current.isCk,
         canImprove = CatanInteraction.improvable(legal).isNotEmpty(),
         canPlayProgress = progressHand.any { it.playable },
@@ -374,7 +379,8 @@ fun CatanScreen(
                         players(false)
                         if (current.isCk) CatanBarbarians(current, style = style)
                         promptRow()
-                        Box(Modifier.weight(1f).fillMaxWidth(), contentAlignment = Alignment.Center) {
+                        // Pinch to zoom and drag to pan, as in landscape: a wide Seafarers map is small at fit.
+                        ZoomPanBox(Modifier.weight(1f).fillMaxWidth()) {
                             board(Modifier)
                         }
                         handAndActions()

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

@@ -124,6 +124,12 @@ private val LightStyle = CatanStyle(
         // 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),
+        // Land not yet found: a pale grey bank of fog with a question mark.
+        Terrain.FOG to Color(0xFFB9C2C9),
+        // Cloth villages: a dyed-cloth purple.
+        Terrain.VILLAGE to Color(0xFF9B6BB5),
+        // A pirate fortress: dark stone.
+        Terrain.FORTRESS to Color(0xFF4A4F57),
     ),
     hexEdge = Color(0x55000000),
     token = Color(0xFFF7EFD9),

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

@@ -74,6 +74,9 @@ object CatanText {
         Terrain.DESERT -> "Desert"
         Terrain.SEA -> "Sea"
         Terrain.GOLD -> "Gold field"
+        Terrain.FOG -> "Fog"
+        Terrain.VILLAGE -> "Village"
+        Terrain.FORTRESS -> "Pirate fortress"
     }
 
     fun devCard(type: DevCardType): String = when (type) {
@@ -113,6 +116,12 @@ object CatanText {
     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 RAID = "Raid"
+    const val RAID_COST = "1 ore + 1 wool + 1 grain"
+    const val DIG = "Dig"
+    const val DIG_COST = "1 brick + 1 ore"
+    const val WONDER = "Wonder"
+    const val WONDER_COST = "next stage"
     const val GOLD_TITLE = "Gold field"
     const val GOLD_TAKE = "Take"
     const val ROLL = "Roll dice"
@@ -193,7 +202,7 @@ object CatanText {
         /** 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)
+        if (state.isCk) return ckPrompt(state, seats, setupVertexChosen, building, movingKnight, armed, movingShip)
         val me = seats.me
         val onClock = CatanRules.currentSeat(state)
         val mine = onClock == me
@@ -246,6 +255,8 @@ object CatanText {
                 !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.RAID -> "Tap a pirate fortress your ship lies beside to raid it."
+                building == BuildKind.DIG -> "Tap a canal tile beside one of your towns to dig a unit."
                 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."
@@ -400,6 +411,7 @@ object CatanText {
         building: BuildKind?,
         movingKnight: Boolean,
         armed: ProgressType?,
+        movingShip: Boolean,
     ): String {
         val me = seats.me
         val onClock = CatanRules.currentSeat(state)
@@ -408,7 +420,12 @@ object CatanText {
         val ck = state.ck!!
 
         return when (state.phase) {
-            CatanPhase.GOLD -> ""
+            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.GAME_OVER -> {
                 val winner = state.winner
@@ -434,6 +451,7 @@ object CatanText {
             CatanPhase.ROBBER -> when {
                 !mine -> "$turn is moving the robber…"
                 ck.bishop -> "The bishop: tap a hex. Everyone beside it pays you a card."
+                state.isSea -> SEA_ROBBER
                 else -> "Move the robber. Tap a hex."
             }
 
@@ -441,6 +459,10 @@ object CatanText {
                 !mine -> "$turn is playing…"
                 armed != null -> armedPrompt(armed)
                 movingKnight -> "Tap where the knight should go."
+                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.RAID -> "Tap a pirate fortress your ship lies beside to raid it."
+                building == BuildKind.DIG -> "Tap a canal tile beside one of your towns to dig a unit."
                 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."

app/src/test/java/org/prolibertate/games/game/backgammon/BackgammonAiProfileTest.kt

@@ -0,0 +1,43 @@
+package org.prolibertate.games.game.backgammon
+
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertTrue
+import org.junit.Test
+import org.prolibertate.games.game.engine.AiDifficulty
+import org.prolibertate.games.game.engine.AiProfiles
+
+class BackgammonAiProfileTest {
+
+    private fun playout(ai: BackgammonAi, seed: Long, steps: Int): List<BackgammonMove> {
+        var state = BackgammonRules.initialState(BackgammonOptions(), seed)
+        val chosen = mutableListOf<BackgammonMove>()
+        repeat(steps) {
+            if (BackgammonRules.isFinished(state)) return chosen
+            val seat = BackgammonRules.currentSeat(state) ?: return chosen
+            val legal = BackgammonRules.legalMoves(state, seat)
+            if (legal.isEmpty()) return chosen
+            val move = ai.chooseMove(state, seat, legal)
+            assertTrue("illegal move $move", move in legal)
+            chosen += move
+            state = BackgammonRules.applyMove(state, seat, move)
+        }
+        return chosen
+    }
+
+    @Test
+    fun everyLevelAndStyleReturnsLegalMoves() {
+        for (difficulty in listOf(AiDifficulty.EASY, AiDifficulty.MEDIUM, AiDifficulty.HARD, AiDifficulty.MIXED)) {
+            for (seed in 0L..5L) {
+                val moves = playout(BackgammonAi(AiProfiles(difficulty, seed)), seed, 14)
+                assertTrue(moves.isNotEmpty())
+            }
+        }
+    }
+
+    @Test
+    fun defaultProfilePlaysAsBefore() {
+        val plain = playout(BackgammonAi(), 3L, 20)
+        val medium = playout(BackgammonAi(AiProfiles(AiDifficulty.MEDIUM, 77L)), 3L, 20)
+        assertEquals(plain, medium)
+    }
+}

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

@@ -0,0 +1,105 @@
+package org.prolibertate.games.game.catan
+
+import kotlinx.serialization.encodeToString
+import kotlinx.serialization.json.Json
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertTrue
+import org.junit.Test
+import org.prolibertate.games.game.GameCatalog
+import org.prolibertate.games.game.engine.AiDifficulty
+import org.prolibertate.games.game.engine.AiProfiles
+import org.prolibertate.games.game.engine.AiStyle
+import org.prolibertate.games.game.engine.PlayerKind
+import org.prolibertate.games.game.engine.PlayerSlot
+import org.prolibertate.games.game.engine.TableConfig
+
+/** Computer seats at every level and style play legal, forward-moving games in each Katan rule set. */
+class CatanAiProfilesTest {
+
+    private val json = Json { encodeDefaults = true }
+
+    private fun config(options: CatanOptions, seed: Long) = TableConfig(
+        gameId = GameCatalog.CATAN,
+        seats = (0 until options.playerCount).map {
+            PlayerSlot(seat = it, name = "P$it", kind = PlayerKind.AI, team = it)
+        },
+        optionsJson = json.encodeToString(options),
+        seed = seed,
+    )
+
+    /** Plays up to [cap] moves, checking every one; returns the last state. */
+    private fun play(options: CatanOptions, seed: Long, profiles: AiProfiles, cap: Int): CatanState {
+        val ai = CatanAi(profiles)
+        var state = CatanRules.initialState(config(options, seed))
+        var moves = 0
+        while (!CatanRules.isFinished(state) && 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: chose $move outside the legal list in ${state.phase}", move in legal || CatanRules.isLegalMove(state, seat, move))
+            assertTrue(
+                "seed $seed: seat $seat chose the illegal move $move in ${state.phase}",
+                CatanRules.isLegalMove(state, seat, move),
+            )
+            state = CatanRules.applyMove(state, seat, move)
+        }
+        return state
+    }
+
+    /** A table seed on which some seat among the first three has [style] at [difficulty]. */
+    private fun tableSeedFor(difficulty: AiDifficulty, style: AiStyle): Long =
+        (1L..2_000L).first { s ->
+            val p = AiProfiles(difficulty, s)
+            (0 until 3).any { p.of(it).style == style }
+        }
+
+    private fun forEveryProfile(rules: Set<CatanExpansion>, cap: Int) {
+        val options = CatanOptions(
+            playerCount = 3,
+            pointsToWin = when {
+                CatanExpansion.CITIES_AND_KNIGHTS in rules -> 13
+                CatanExpansion.SEAFARERS in rules -> 12
+                else -> 10
+            },
+            expansions = rules,
+        )
+        for (difficulty in listOf(AiDifficulty.EASY, AiDifficulty.HARD)) {
+            for (style in AiStyle.entries) {
+                val tableSeed = tableSeedFor(difficulty, style)
+                val state = play(options, 40L + style.ordinal, AiProfiles(difficulty, tableSeed), cap)
+                assertTrue(
+                    "$rules $difficulty $style: the game never got past setup",
+                    state.turnNumber > 3 || CatanRules.isFinished(state),
+                )
+            }
+        }
+    }
+
+    @Test
+    fun `easy and hard seats of every style play the base game`() = forEveryProfile(emptySet(), 1_500)
+
+    @Test
+    fun `easy and hard seats of every style play Cities and Knights`() =
+        forEveryProfile(setOf(CatanExpansion.CITIES_AND_KNIGHTS), 1_500)
+
+    @Test
+    fun `easy and hard seats of every style play Seafarers`() = forEveryProfile(setOf(CatanExpansion.SEAFARERS), 1_500)
+
+    @Test
+    fun `a mixed table of four finishes a base game`() {
+        val state = play(CatanOptions(playerCount = 4), 77L, AiProfiles(AiDifficulty.MIXED, 5L), 12_000)
+        assertEquals(CatanPhase.GAME_OVER, state.phase)
+    }
+
+    @Test
+    fun `the default profile plays exactly as an explicit medium table does`() {
+        for (rules in listOf(emptySet(), setOf(CatanExpansion.CITIES_AND_KNIGHTS))) {
+            val options = CatanOptions(playerCount = 3, pointsToWin = 10, expansions = rules)
+            val plain = play(options, 9L, AiProfiles.DEFAULT, 600)
+            val medium = play(options, 9L, AiProfiles(AiDifficulty.MEDIUM, 1234L), 600)
+            assertEquals("$rules", plain, medium)
+        }
+    }
+}

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

@@ -0,0 +1,115 @@
+package org.prolibertate.games.game.catan
+
+import kotlinx.serialization.encodeToString
+import kotlinx.serialization.json.Json
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertNotEquals
+import org.junit.Assert.assertNull
+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
+
+/** The base-island scenarios: First Island's fixed board and the Harbormaster. */
+class CatanBaseScenarioTest {
+
+    private val json = Json { encodeDefaults = true }
+
+    private fun config(options: CatanOptions, seed: Long) = TableConfig(
+        gameId = GameCatalog.CATAN,
+        seats = (0 until options.playerCount).map { PlayerSlot(seat = it, name = "P$it", kind = PlayerKind.AI, team = it) },
+        optionsJson = json.encodeToString(options),
+        seed = seed,
+    )
+
+    private fun game(
+        scenario: BaseScenario,
+        seed: Long = 5L,
+        expansions: Set<CatanExpansion> = emptySet(),
+        players: Int = 3,
+    ) = CatanRules.initialState(config(CatanOptions(players, 10, expansions, baseScenario = scenario), seed))
+
+    @Test
+    fun `first island is the same board for every seed and the random map is not`() {
+        val a = game(BaseScenario.FIRST_ISLAND, 1L)
+        val b = game(BaseScenario.FIRST_ISLAND, 99L)
+        assertEquals(a.terrains, b.terrains)
+        assertEquals(a.numbers, b.numbers)
+        assertEquals(a.ports, b.ports)
+        assertNotEquals(game(BaseScenario.RANDOM_MAP, 1L).terrains, game(BaseScenario.RANDOM_MAP, 99L).terrains)
+        // The deck and the seating still follow the table's own seed.
+        assertNotEquals(a.devDeck, b.devDeck)
+    }
+
+    @Test
+    fun `a save from before base scenarios reads as a random map`() {
+        val old = """{"playerCount":3,"pointsToWin":10,"expansions":[],"scenario":"NEW_SHORES"}"""
+        assertEquals(BaseScenario.RANDOM_MAP, json.decodeFromString<CatanOptions>(old).baseScenario)
+        val options = CatanOptions(3, 10, baseScenario = BaseScenario.HARBORMASTER)
+        assertEquals(options, json.decodeFromString<CatanOptions>(json.encodeToString(options)))
+    }
+
+    /** Vertices of the harbours, one per harbour, in board order. */
+    private fun CatanState.harbourVertices(): List<Int> = ports.map { topo.EDGE_VERTICES[it.edge].first }
+
+    private fun CatanState.with(seat: Int, vertex: Int, type: BuildingType) =
+        copy(buildings = buildings.toMutableList().also { it[vertex] = CatanBuilding(type, seat) })
+
+    @Test
+    fun `three harbour points make a harbormaster and more takes the title`() {
+        var s = game(BaseScenario.HARBORMASTER).copy(phase = CatanPhase.PLAYING, turn = 0, turnNumber = 1)
+        val v = s.harbourVertices()
+        s = s.with(0, v[0], BuildingType.SETTLEMENT).with(0, v[1], BuildingType.SETTLEMENT)
+        assertEquals(2, CatanRules.harbourPoints(s, 0))
+        assertNull(CatanRules.refreshHarbormaster(s).harbormaster)
+
+        // A city counts two: 1 + 2 = 3.
+        s = CatanRules.refreshHarbormaster(s.with(0, v[1], BuildingType.CITY))
+        assertEquals(3, CatanRules.harbourPoints(s, 0))
+        assertEquals(0, s.harbormaster)
+        assertEquals(CatanRules.publicVictoryPoints(s.copy(harbormaster = null))[0] + 2, CatanRules.publicVictoryPoints(s)[0])
+
+        // Equal points do not take it; strictly more does.
+        s = CatanRules.refreshHarbormaster(
+            s.with(1, v[2], BuildingType.SETTLEMENT).with(1, v[3], BuildingType.SETTLEMENT).with(1, v[4], BuildingType.SETTLEMENT),
+        )
+        assertEquals(0, s.harbormaster)
+        s = CatanRules.refreshHarbormaster(s.with(1, v[5], BuildingType.SETTLEMENT))
+        assertEquals(1, s.harbormaster)
+        assertTrue(s.log.any { "taken the title harbormaster from seat 0" in it })
+    }
+
+    @Test
+    fun `the title does not exist in other scenarios or in a Seafarers game`() {
+        var s = game(BaseScenario.RANDOM_MAP).copy(phase = CatanPhase.PLAYING)
+        val v = s.harbourVertices()
+        for (i in 0..3) s = s.with(0, v[i], BuildingType.SETTLEMENT)
+        assertNull(CatanRules.refreshHarbormaster(s).harbormaster)
+    }
+
+    @Test
+    fun `engines finish games on the base scenarios, with and without Cities and Knights`() {
+        var titles = 0
+        for (scenario in listOf(BaseScenario.FIRST_ISLAND, BaseScenario.HARBORMASTER)) {
+            for (expansions in listOf(emptySet(), setOf(CatanExpansion.CITIES_AND_KNIGHTS))) {
+                for ((players, seed) in listOf(3 to 31L, 4 to 32L)) {
+                    val opts = CatanOptions(players, if (expansions.isEmpty()) 10 else 13, expansions, baseScenario = scenario)
+                    var state = CatanRules.initialState(config(opts, seed))
+                    val ai = CatanAi()
+                    var moves = 0
+                    while (!CatanRules.isFinished(state)) {
+                        assertTrue("$scenario $expansions seed $seed ran long", moves++ < 20_000)
+                        val seat = CatanRules.currentSeat(state)!!
+                        val legal = CatanRules.legalMoves(state, seat)
+                        state = CatanRules.applyMove(state, seat, ai.chooseMove(state, seat, legal))
+                    }
+                    if (state.harbormaster != null) titles++
+                    assertEquals(state, CatanRules.decodeState(CatanRules.encodeState(state)))
+                }
+            }
+        }
+        assertTrue("nobody ever became harbormaster", titles > 0)
+    }
+}

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

@@ -25,7 +25,7 @@ class CatanCkRulesTest {
             CatanOptions(
                 playerCount = players,
                 pointsToWin = 13,
-                ruleSet = if (ck) CatanRuleSet.CITIES_AND_KNIGHTS else CatanRuleSet.BASE,
+                expansions = if (ck) setOf(CatanExpansion.CITIES_AND_KNIGHTS) else emptySet(),
             ),
         ),
         seed = seed,
@@ -138,7 +138,7 @@ class CatanCkRulesTest {
         val base = CatanRules.initialState(config(ck = false))
         assertNull(base.ck)
         assertEquals(25, base.devDeck.size)
-        assertEquals(CatanRuleSet.BASE, base.options.ruleSet)
+        assertEquals(emptySet<CatanExpansion>(), base.options.expansions)
     }
 
     @Test
@@ -157,7 +157,21 @@ class CatanCkRulesTest {
     fun `the options without a rule set still read as the base game`() {
         val old = """{"playerCount":4,"pointsToWin":10}"""
         val options = Json { ignoreUnknownKeys = true }.decodeFromString<CatanOptions>(old)
-        assertEquals(CatanRuleSet.BASE, options.ruleSet)
+        assertEquals(emptySet<CatanExpansion>(), options.expansions)
+    }
+
+    @Test
+    fun `options saved with a rule set still read as the expansion they named`() {
+        val read = { text: String -> Json { ignoreUnknownKeys = true }.decodeFromString<CatanOptions>(text) }
+        assertEquals(
+            setOf(CatanExpansion.CITIES_AND_KNIGHTS),
+            read("""{"playerCount":3,"pointsToWin":13,"ruleSet":"CITIES_AND_KNIGHTS"}""").expansions,
+        )
+        assertEquals(
+            setOf(CatanExpansion.SEAFARERS),
+            read("""{"playerCount":3,"pointsToWin":12,"ruleSet":"SEAFARERS"}""").expansions,
+        )
+        assertEquals(emptySet<CatanExpansion>(), read("""{"ruleSet":"BASE"}""").expansions)
     }
 
     @Test

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

@@ -152,7 +152,7 @@ class CatanCkSelfPlayTest {
     fun `three engines play Cities and Knights to a finish`() {
         val reports = (1L..12L).map { seed ->
             val (state, report) = playOut(
-                CatanOptions(playerCount = 3, pointsToWin = 13, ruleSet = CatanRuleSet.CITIES_AND_KNIGHTS),
+                CatanOptions(playerCount = 3, pointsToWin = 13, expansions = setOf(CatanExpansion.CITIES_AND_KNIGHTS)),
                 seed,
             )
             assertEquals("seed $seed", CatanPhase.GAME_OVER, state.phase)
@@ -171,7 +171,7 @@ class CatanCkSelfPlayTest {
     fun `four engines play Cities and Knights to a finish`() {
         val reports = (101L..108L).map { seed ->
             val (state, report) = playOut(
-                CatanOptions(playerCount = 4, pointsToWin = 13, ruleSet = CatanRuleSet.CITIES_AND_KNIGHTS),
+                CatanOptions(playerCount = 4, pointsToWin = 13, expansions = setOf(CatanExpansion.CITIES_AND_KNIGHTS)),
                 seed,
             )
             assertEquals("seed $seed", CatanPhase.GAME_OVER, state.phase)

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

@@ -115,8 +115,9 @@ class CatanRulesTest {
     // -- Setup ---------------------------------------------------------------
 
     @Test
-    fun `setup runs in snake order and then seat zero leads`() {
+    fun `setup runs in snake order from the first seat and then that seat leads`() {
         var state = CatanRules.initialState(config())
+        val first = state.firstSeat
         val order = mutableListOf<Int>()
         while (state.phase == CatanPhase.SETUP_FIRST || state.phase == CatanPhase.SETUP_SECOND) {
             val seat = CatanRules.currentSeat(state)!!
@@ -126,12 +127,21 @@ class CatanRulesTest {
                 CatanRules.legalMoves(state, seat).filterIsInstance<SetupPlace>().first(),
             )
         }
-        assertEquals(listOf(0, 1, 2, 2, 1, 0), order)
+        val forward = (0 until 3).map { (first + it) % 3 }
+        assertEquals(forward + forward.reversed(), order)
         assertEquals(CatanPhase.AWAIT_ROLL, state.phase)
-        assertEquals(0, state.turn)
+        assertEquals(first, state.turn)
         assertEquals(1, state.turnNumber)
     }
 
+    @Test
+    fun `the first seat comes from the seed and varies between tables`() {
+        val firsts = (1L..40L).map { CatanRules.initialState(config(seed = it)).firstSeat }
+        assertEquals(firsts, (1L..40L).map { CatanRules.initialState(config(seed = it)).firstSeat })
+        assertEquals(setOf(0, 1, 2), firsts.toSet())
+        assertEquals(firsts[0], CatanRules.initialState(config(seed = 1L)).turn)
+    }
+
     @Test
     fun `the second settlement earns one card from each adjacent land`() {
         var state = CatanRules.initialState(config())

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

@@ -0,0 +1,154 @@
+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.assertNotNull
+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
+
+/** Cities & Knights played on a Seafarers map. */
+class CatanSeaCkTest {
+
+    private val json = Json { encodeDefaults = true }
+
+    private fun options(scenario: SeaScenario = SeaScenario.NEW_SHORES, players: Int = 3) = CatanOptions(
+        playerCount = players,
+        pointsToWin = 14,
+        expansions = setOf(CatanExpansion.CITIES_AND_KNIGHTS, CatanExpansion.SEAFARERS),
+        scenario = scenario,
+    )
+
+    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(scenario: SeaScenario = SeaScenario.NEW_SHORES, seed: Long = 7L) =
+        CatanRules.initialState(config(options(scenario), seed))
+
+    private fun CatanState.city(vertex: Int, seat: Int) =
+        copy(buildings = buildings.toMutableList().also { it[vertex] = CatanBuilding(BuildingType.CITY, seat) })
+
+    @Test
+    fun `both expansions switch on together and the state carries both`() {
+        val s = start()
+        assertNotNull(s.ck)
+        assertNotNull(s.sea)
+        assertTrue(s.devDeck.isEmpty())
+        assertEquals(setOf(CatanExpansion.CITIES_AND_KNIGHTS, CatanExpansion.SEAFARERS), s.options.expansions)
+        assertEquals(s, CatanRules.decodeState(CatanRules.encodeState(s)))
+    }
+
+    @Test
+    fun `a ship is on offer in play, and a knight can stand at the end of a ship route on land`() {
+        val s0 = start()
+        val topo = s0.topo
+        // A coastal home town with a sea edge leaving it.
+        val town = (0 until topo.VERTEX_COUNT).first { v ->
+            topo.vertexIsland[v] == s0.sea!!.home &&
+                topo.VERTEX_EDGES[v].any { topo.edgeSea[it] && !topo.edgeLand[it] }
+        }
+        val s = s0.city(town, 0).copy(
+            phase = CatanPhase.PLAYING, turn = 0, turnNumber = 3,
+            resources = List(3) { Resource.entries.associateWith { 5 } },
+        )
+        val moves = CatanRules.legalMoves(s, 0)
+        assertTrue("no ship on offer", moves.any { it is BuildShip })
+        assertTrue("sea vertices are never knight posts", moves.filterIsInstance<HireKnight>().all { topo.vertexLand[it.vertex] })
+    }
+
+    @Test
+    fun `a gold field pays its owner a choice after the roll, then play goes on`() {
+        val s0 = start()
+        val topo = s0.topo
+        val gold = s0.terrains.indexOf(Terrain.GOLD)
+        val number = s0.numbers[gold]
+        val vertex = topo.HEX_CORNERS[gold].first { topo.vertexLand[it] }
+        val dice = (1..6).flatMap { a -> (1..6).map { b -> listOf(a, b) } }.first { it.sum() == number }
+        val s = s0.city(vertex, 0).copy(phase = CatanPhase.AWAIT_ROLL, turn = 0, turnNumber = 3, robber = 0)
+        val rolled = CatanRules.applyMove(s, 0, RollDice(forced = dice, event = EventFace.TRADE))
+        assertEquals(CatanPhase.GOLD, rolled.phase)
+        assertEquals(listOf(GoldOwed(0, 2)), rolled.sea!!.gold)
+        val pick = CatanRules.legalMoves(rolled, 0).filterIsInstance<PickGold>().first { it.cards == listOf(Resource.ORE, Resource.ORE) }
+        val after = CatanRules.applyMove(rolled, 0, pick)
+        assertEquals(CatanPhase.PLAYING, after.phase)
+        assertEquals(2, after.resources[0].getValue(Resource.ORE) - s.resources[0].getValue(Resource.ORE))
+    }
+
+    @Test
+    fun `once the barbarians have landed a seven may send the pirate, which robs goods`() {
+        val s0 = start()
+        val topo = s0.topo
+        val seaHex = (0 until topo.HEX_COUNT).first { !topo.land[it] && it != s0.sea!!.pirate &&
+            (0 until topo.EDGE_COUNT).any { e -> it in topo.EDGE_HEXES[e] && topo.edgeLand[e] } }
+        val edge = (0 until topo.EDGE_COUNT).first { seaHex in topo.EDGE_HEXES[it] }
+        val s = s0.copy(
+            phase = CatanPhase.ROBBER, turn = 0, turnNumber = 3,
+            ck = s0.ck!!.copy(attacked = true),
+            sea = s0.sea!!.copy(ships = s0.sea!!.ships.toMutableList().also { it[edge] = 1 }),
+            resources = s0.resources.toMutableList().also { it[1] = it[1] + (Resource.GRAIN to 2) },
+        )
+        val pirate = CatanRules.legalMoves(s, 0).filterIsInstance<MovePirate>()
+            .first { it.hex == topo.HEXES[seaHex] && it.victim == 1 }
+        val after = CatanRules.applyMove(s, 0, pirate)
+        assertEquals(seaHex, after.sea!!.pirate)
+        assertEquals(CatanPhase.PLAYING, after.phase)
+        assertEquals(CatanCk.goodsCount(s, 0) + 1, CatanCk.goodsCount(after, 0))
+        assertEquals(CatanCk.goodsCount(s, 1) - 1, CatanCk.goodsCount(after, 1))
+        // The robber itself is kept off the sea and the fog.
+        val robber = CatanRules.legalMoves(s, 0).filterIsInstance<MoveRobber>()
+        assertTrue(robber.all { topo.land[topo.hexIndex.getValue(it.hex)] })
+    }
+
+    @Test
+    fun `first landings count toward the target`() {
+        val s0 = start()
+        val sea = s0.sea!!
+        val islet = (0 until s0.topo.islandCount).first { !sea.isStart(it) }
+        val withBonus = s0.copy(sea = sea.copy(islandBonus = sea.islandBonus.toMutableList().also { it[islet] = 2 }))
+        assertEquals(CatanCk.publicVictoryPoints(s0)[2] + SeaRules.ISLAND_BONUS, CatanCk.publicVictoryPoints(withBonus)[2])
+    }
+
+    @Test
+    fun `engines finish a Cities and Knights game on three maps`() {
+        var ships = 0
+        var knights = 0
+        var barbarianAttacks = 0
+        for ((scenario, players, seed) in listOf(
+            Triple(SeaScenario.NEW_SHORES, 3, 21L),
+            Triple(SeaScenario.FOUR_ISLANDS, 4, 22L),
+            Triple(SeaScenario.FOG_ISLANDS, 3, 23L),
+        )) {
+            val ai = CatanAi()
+            var state = CatanRules.initialState(config(options(scenario, players), seed))
+            var moves = 0
+            while (!CatanRules.isFinished(state)) {
+                assertTrue("$scenario seed $seed ran past the cap; log: ${state.log.takeLast(6)}", moves++ < 40_000)
+                val seat = CatanRules.currentSeat(state) ?: error("$scenario: nobody to move in ${state.phase}; ${state.log.takeLast(4)}")
+                val legal = CatanRules.legalMoves(state, seat)
+                assertTrue("$scenario: no legal move for $seat in ${state.phase}", legal.isNotEmpty())
+                val move = ai.chooseMove(state, seat, legal)
+                assertTrue("$scenario: illegal $move in ${state.phase}", CatanRules.isLegalMove(state, seat, move))
+                state = CatanRules.applyMove(state, seat, move)
+                if (moves % 40 == 0) assertEquals(state, CatanRules.decodeState(CatanRules.encodeState(state)))
+            }
+            assertFalse(state.winner == null)
+            ships += state.sea!!.ships.count { it != NO_PLAYER }
+            knights += state.ck!!.knights.size
+            if (state.ck!!.attacked) barbarianAttacks++
+        }
+        assertTrue("no ships were built", ships > 0)
+        assertTrue("no knights were hired", knights > 0)
+        assertTrue("the barbarians never landed", barbarianAttacks > 0)
+    }
+}

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

@@ -0,0 +1,336 @@
+package org.prolibertate.games.game.catan
+
+import kotlinx.serialization.encodeToString
+import kotlinx.serialization.json.Json
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertTrue
+import org.junit.Test
+import org.prolibertate.games.game.GameCatalog
+import org.prolibertate.games.game.engine.PlayerKind
+import org.prolibertate.games.game.engine.PlayerSlot
+import org.prolibertate.games.game.engine.TableConfig
+
+/** The scenarios with rules of their own: cloth villages and tribe chips. */
+class CatanSeaExtrasTest {
+
+    private val json = Json { encodeDefaults = true }
+
+    private fun start(scenario: SeaScenario, seed: Long = 5L, players: Int = 3): CatanState {
+        val options = CatanOptions(
+            playerCount = players,
+            pointsToWin = 14,
+            expansions = setOf(CatanExpansion.SEAFARERS),
+            scenario = scenario,
+        )
+        val config = TableConfig(
+            gameId = GameCatalog.CATAN,
+            seats = (0 until players).map { PlayerSlot(seat = it, name = "P$it", kind = PlayerKind.AI, team = it) },
+            optionsJson = json.encodeToString(options),
+            seed = seed,
+        )
+        return CatanRules.initialState(config).copy(phase = CatanPhase.AWAIT_ROLL, turn = 0, turnNumber = 1, setupIndex = 6)
+    }
+
+    private fun dice(total: Int): List<Int> = if (total <= 7) listOf(1, total - 1) else listOf(total - 6, 6)
+
+    /** A cloth game with seat 0 and seat 1 both settled beside the first village, the robber elsewhere. */
+    private fun clothGame(): Pair<CatanState, Int> {
+        val s = start(SeaScenario.CLOTH_FOR_CATAN)
+        val village = s.terrains.indexOf(Terrain.VILLAGE)
+        val corners = s.topo.HEX_CORNERS[village]
+        val elsewhere = s.terrains.indices.first { s.topo.land[it] && it != village && s.terrains[it] != Terrain.VILLAGE }
+        val staged = s.copy(
+            robber = elsewhere,
+            buildings = s.buildings.toMutableList().also {
+                it[corners[0]] = CatanBuilding(BuildingType.SETTLEMENT, 0)
+                it[corners[3]] = CatanBuilding(BuildingType.CITY, 1)
+            },
+        )
+        return staged to village
+    }
+
+    private fun roll(s: CatanState, number: Int) = CatanRules.applyMove(s, s.turn, RollDice(dice(number)))
+
+    @Test
+    fun `a village pays one cloth to every settlement beside it, a city no more`() {
+        val (s, village) = clothGame()
+        val number = s.numbers[village]
+        assertTrue(number in 2..12 && number != 7)
+        val after = roll(s, number)
+        assertEquals(listOf(1, 1, 0), after.sea!!.cloth)
+        assertEquals(SeaBoards.VILLAGE_CLOTH - 2, after.sea!!.villageCloth[village])
+        assertTrue(after.log.any { "village" in it && "cloth" in it })
+    }
+
+    @Test
+    fun `an empty village pays nothing and the last token goes to the seat nearest the roller`() {
+        val (s, village) = clothGame()
+        val low = s.copy(sea = s.sea!!.copy(villageCloth = s.sea!!.villageCloth.toMutableList().also { it[village] = 1 }))
+        val after = roll(low.copy(turn = 1), low.numbers[village])
+        assertEquals(listOf(0, 1, 0), after.sea!!.cloth)
+        assertEquals(0, after.sea!!.villageCloth[village])
+        val again = roll(after.copy(phase = CatanPhase.AWAIT_ROLL), after.numbers[village])
+        assertEquals(listOf(0, 1, 0), again.sea!!.cloth)
+    }
+
+    @Test
+    fun `the robber on a village stops it`() {
+        val (s, village) = clothGame()
+        val after = roll(s.copy(robber = village), s.numbers[village])
+        assertEquals(listOf(0, 0, 0), after.sea!!.cloth)
+    }
+
+    @Test
+    fun `every two cloth are a victory point, and the whole thing survives the wire format`() {
+        val (s, _) = clothGame()
+        val rich = s.copy(sea = s.sea!!.copy(cloth = listOf(5, 1, 0)))
+        assertEquals(CatanRules.publicVictoryPoints(s)[0] + 2, CatanRules.publicVictoryPoints(rich)[0])
+        assertEquals(CatanRules.publicVictoryPoints(s)[1], CatanRules.publicVictoryPoints(rich)[1])
+        assertEquals(rich, CatanRules.decodeState(CatanRules.encodeState(rich)))
+    }
+
+    @Test
+    fun `villages pay cloth with Cities and Knights too`() {
+        val options = CatanOptions(
+            playerCount = 3,
+            pointsToWin = 14,
+            expansions = setOf(CatanExpansion.SEAFARERS, CatanExpansion.CITIES_AND_KNIGHTS),
+            scenario = SeaScenario.CLOTH_FOR_CATAN,
+        )
+        val config = TableConfig(
+            gameId = GameCatalog.CATAN,
+            seats = (0 until 3).map { PlayerSlot(seat = it, name = "P$it", kind = PlayerKind.AI, team = it) },
+            optionsJson = json.encodeToString(options),
+            seed = 5L,
+        )
+        val s = CatanRules.initialState(config)
+            .copy(phase = CatanPhase.AWAIT_ROLL, turn = 0, turnNumber = 1, setupIndex = 6)
+        val village = s.terrains.indexOf(Terrain.VILLAGE)
+        val elsewhere = s.terrains.indices.first { s.topo.land[it] && it != village && s.terrains[it] != Terrain.VILLAGE }
+        val staged = s.copy(
+            robber = elsewhere,
+            buildings = s.buildings.toMutableList().also {
+                it[s.topo.HEX_CORNERS[village][0]] = CatanBuilding(BuildingType.SETTLEMENT, 2)
+            },
+        )
+        val after = roll(staged, staged.numbers[village])
+        assertEquals(1, after.sea!!.cloth[2])
+    }
+
+    // ---- The Forgotten Tribe ----
+
+    /** A tribe game, seat 0 with a road reaching a settlement site beside [chipHex], and plenty of cards. */
+    private fun tribeGame(chip: TribeChip): Triple<CatanState, Int, Int> {
+        val s = start(SeaScenario.FORGOTTEN_TRIBE)
+        val hex = s.sea!!.chips.indexOfFirst { it != TribeChip.NONE }
+        val chips = s.sea!!.chips.toMutableList().also { it[hex] = chip }
+        val topo = s.topo
+        val vertex = topo.HEX_CORNERS[hex].first { v -> topo.VERTEX_NEIGHBORS[v].all { s.buildings[it] == null } }
+        val edge = topo.VERTEX_EDGES[vertex].first { topo.edgeLand[it] }
+        val staged = s.copy(
+            phase = CatanPhase.PLAYING,
+            roads = s.roads.toMutableList().also { it[edge] = 0 },
+            resources = List(3) { Resource.entries.associateWith { 4 } },
+            sea = s.sea!!.copy(chips = chips),
+        )
+        return Triple(staged, hex, vertex)
+    }
+
+    @Test
+    fun `the first settler beside a point chip takes the point`() {
+        val (s, hex, vertex) = tribeGame(TribeChip.POINT)
+        val after = CatanRules.applyMove(s, 0, BuildSettlement(vertex))
+        assertEquals(1, after.sea!!.chipPoints[0])
+        assertEquals(TribeChip.NONE, after.sea!!.chips[hex])
+        assertEquals(CatanRules.publicVictoryPoints(s)[0] + 1 + 1 + 2, CatanRules.publicVictoryPoints(after)[0])
+    }
+
+    @Test
+    fun `a harbour chip trades three to one anywhere`() {
+        val (s, _, vertex) = tribeGame(TribeChip.HARBOUR)
+        assertEquals(4, CatanRules.bestPortRatio(s, 0, Resource.WOOL))
+        val after = CatanRules.applyMove(s, 0, BuildSettlement(vertex))
+        assertEquals(listOf(0), after.sea!!.harbourSeats)
+        assertEquals(3, CatanRules.bestPortRatio(after, 0, Resource.WOOL))
+        assertEquals(4, CatanRules.bestPortRatio(after, 1, Resource.WOOL))
+        assertTrue(CatanRules.legalMoves(after, 0).any { it is MaritimeTrade })
+    }
+
+    @Test
+    fun `a gold chip asks for two resources of the settler's choice`() {
+        val (s, _, vertex) = tribeGame(TribeChip.GOLD)
+        val after = CatanRules.applyMove(s, 0, BuildSettlement(vertex))
+        assertEquals(CatanPhase.GOLD, after.phase)
+        assertEquals(listOf(GoldOwed(0, 2)), after.sea!!.gold)
+        val done = CatanRules.applyMove(after, 0, CatanRules.legalMoves(after, 0).first())
+        assertEquals(CatanPhase.PLAYING, done.phase)
+    }
+
+    // ---- Pirate Islands ----
+
+    private fun fortGame(): Triple<CatanState, Int, Int> {
+        val s = start(SeaScenario.PIRATE_ISLANDS).copy(
+            phase = CatanPhase.PLAYING,
+            resources = List(3) { Resource.entries.associateWith { 6 } },
+        )
+        val fort = s.terrains.indexOf(Terrain.FORTRESS)
+        val edge = (0 until s.topo.EDGE_COUNT).first { s.topo.edgeSea[it] && fort in s.topo.EDGE_HEXES[it] }
+        return Triple(s, fort, edge)
+    }
+
+    @Test
+    fun `nobody settles a fortress island until the fortress falls`() {
+        val (s, fort, _) = fortGame()
+        val corner = s.topo.HEX_CORNERS[fort].first()
+        assertTrue(SeaRules.fortressHolds(s, corner))
+        assertTrue(!CatanRules.vertexOpenForSettlement(s, corner))
+        val fort2 = s.terrains.indices.first { s.terrains[it] == Terrain.FORTRESS && it != fort }
+        assertTrue(s.topo.islandOf[fort] != s.topo.islandOf[fort2])
+    }
+
+    @Test
+    fun `a raid needs a ship beside the fortress and three cards, and three raids take it`() {
+        val (s, fort, edge) = fortGame()
+        val coord = s.topo.HEXES[fort]
+        assertTrue(CatanRules.legalMoves(s, 0).none { it is RaidFortress })
+        var state = s.copy(sea = s.sea!!.copy(ships = s.sea!!.ships.toMutableList().also { it[edge] = 0 }))
+        assertTrue(RaidFortress(coord) in CatanRules.legalMoves(state, 0))
+        val before = state.resources[0].getValue(Resource.ORE)
+        repeat(3) { state = CatanRules.applyMove(state, 0, RaidFortress(coord)) }
+        assertEquals(before - 3, state.resources[0].getValue(Resource.ORE))
+        assertEquals(Terrain.DESERT, state.terrains[fort])
+        assertEquals(2, state.sea!!.raidPoints[0])
+        assertTrue(!SeaRules.fortressHolds(state, s.topo.HEX_CORNERS[fort].first()))
+        assertTrue(CatanRules.legalMoves(state, 0).none { it is RaidFortress })
+        // Seat 1 has no ship there and cannot raid.
+        assertTrue(CatanRules.legalMoves(state.copy(turn = 1), 1).none { it is RaidFortress })
+    }
+
+    // ---- Wonders of Catan ----
+
+    private fun wonderGame(city: Boolean = true): CatanState {
+        val s = start(SeaScenario.WONDERS_OF_CATAN).copy(
+            phase = CatanPhase.PLAYING,
+            resources = List(3) { Resource.entries.associateWith { 9 } },
+        )
+        return if (!city) s else s.copy(
+            buildings = s.buildings.toMutableList().also { it[0] = CatanBuilding(BuildingType.CITY, 0) },
+        )
+    }
+
+    @Test
+    fun `a wonder needs a city, each stage is a point, and the fourth stage wins`() {
+        assertTrue(CatanRules.legalMoves(wonderGame(city = false), 0).none { it is BuildWonder })
+        var s = wonderGame()
+        val base = CatanRules.publicVictoryPoints(s)[0]
+        for (stage in 1..3) {
+            assertTrue(BuildWonder in CatanRules.legalMoves(s, 0))
+            s = CatanRules.applyMove(s, 0, BuildWonder)
+            assertEquals(stage, s.sea!!.wonders[0])
+            assertEquals(base + stage, CatanRules.publicVictoryPoints(s)[0])
+            assertEquals(CatanPhase.PLAYING, s.phase)
+        }
+        s = CatanRules.applyMove(s, 0, BuildWonder)
+        assertEquals(CatanPhase.GAME_OVER, s.phase)
+        assertEquals(0, s.winner)
+        assertEquals(s, CatanRules.decodeState(CatanRules.encodeState(s)))
+    }
+
+    @Test
+    fun `a wonder stage is not offered without the cards`() {
+        val s = wonderGame().copy(resources = List(3) { Resource.entries.associateWith { 0 } })
+        assertTrue(CatanRules.legalMoves(s, 0).none { it is BuildWonder })
+    }
+
+    // ---- Treasure Islands, Oases ----
+
+    @Test
+    fun `chests lie under the fog and are hidden from other views`() {
+        for (scenario in listOf(SeaScenario.TREASURE_ISLANDS, SeaScenario.OASES)) {
+            val s = start(scenario)
+            val chests = s.sea!!.treasures.indices.filter { s.sea!!.treasures[it] != Treasure.NONE }
+            assertEquals(minOf(5, s.terrains.count { it == Terrain.FOG }), chests.size)
+            assertTrue(chests.all { s.terrains[it] == Terrain.FOG })
+            assertTrue(CatanRules.viewFor(s, 1).sea!!.treasures.isEmpty())
+        }
+    }
+
+    @Test
+    fun `an oasis map starts everyone on the desert island, never beside an oasis`() {
+        val s = start(SeaScenario.OASES)
+        assertEquals(37, s.topo.islandOf.count { it == s.sea!!.home })
+        val moves = CatanRules.legalMoves(s.copy(phase = CatanPhase.SETUP_FIRST), s.firstSeat).filterIsInstance<SetupPlace>()
+        assertTrue(moves.isNotEmpty())
+        assertTrue(moves.all { m -> s.topo.VERTEX_HEXES[m.vertex].none { s.terrains[it] == Terrain.FOG } })
+    }
+
+    /** A chest of [kind] under the first fog hex, with a road of seat 0's laid up to the edge that will reveal it. */
+    private fun chestGame(kind: Treasure): Triple<CatanState, Int, Int> {
+        val s = start(SeaScenario.OASES).copy(phase = CatanPhase.PLAYING)
+        val topo = s.topo
+        val hex = s.terrains.indexOf(Terrain.FOG)
+        val chests = List(topo.HEX_COUNT) { if (it == hex) kind else Treasure.NONE }
+        // Seat 0 owns the town beside a road that reaches the oasis; building the road finds it.
+        val edge = topo.EDGE_VERTICES.indices.first { e -> hex in topo.EDGE_HEXES[e] && topo.edgeLand[e] }
+        val staged = s.copy(
+            resources = List(3) { Resource.entries.associateWith { 5 } },
+            sea = s.sea!!.copy(treasures = chests),
+        )
+        return Triple(staged, hex, edge)
+    }
+
+    @Test
+    fun `opening a chest pays its reward`() {
+        val kinds = listOf(Treasure.BRICK_WOOL_GRAIN, Treasure.ROADS, Treasure.DEV_CARD, Treasure.CHOICE)
+        for (kind in kinds) {
+            val (s, _, _) = chestGame(kind)
+            // Stage the find directly: reveal as if a road had just reached the hex.
+            val topo = s.topo
+            val hex = s.terrains.indexOf(Terrain.FOG)
+            val edge = (0 until topo.EDGE_COUNT).first { hex in topo.EDGE_HEXES[it] && topo.edgeLand[it] }
+            val after = SeaRules.reveal(s, 0, edge)
+            assertTrue("$kind: the chest is announced", after.log.any { "treasure chest" in it })
+            when (kind) {
+                Treasure.DEV_CARD -> assertEquals(1, after.devHands[0].size)
+                Treasure.CHOICE -> assertTrue(after.phase == CatanPhase.GOLD || after.log.any { "uncovers" in it })
+                Treasure.ROADS -> assertTrue(after.resources[0].getValue(Resource.LUMBER) >= 7)
+                else -> assertTrue(after.resources[0].getValue(Resource.WOOL) >= 6)
+            }
+        }
+    }
+
+    // ---- The Great Canal ----
+
+    private fun canalGame(): Triple<CatanState, Int, CatanState> {
+        val s = start(SeaScenario.GREAT_CANAL).copy(
+            phase = CatanPhase.PLAYING,
+            resources = List(3) { Resource.entries.associateWith { 9 } },
+        )
+        val tile = s.sea!!.canalNumbers.indexOfFirst { it != 0 }
+        val staged = s.copy(
+            buildings = s.buildings.toMutableList().also {
+                it[s.topo.HEX_CORNERS[tile][0]] = CatanBuilding(BuildingType.SETTLEMENT, 0)
+            },
+        )
+        return Triple(staged, tile, s)
+    }
+
+    @Test
+    fun `a canal tile hides its number, and three digs turn it into fields`() {
+        var (s, tile, _) = canalGame()
+        assertEquals(0, s.numbers[tile])
+        assertEquals(Terrain.DESERT, s.terrains[tile])
+        val number = s.sea!!.canalNumbers[tile]
+        val dig = DigCanal(s.topo.HEXES[tile])
+        assertTrue(dig in CatanRules.legalMoves(s, 0))
+        assertTrue(CatanRules.legalMoves(s.copy(turn = 1), 1).none { it is DigCanal })
+        val before = CatanRules.publicVictoryPoints(s)[0]
+        repeat(2) { s = CatanRules.applyMove(s, 0, dig) }
+        assertEquals(Terrain.DESERT, s.terrains[tile])
+        assertEquals(before + 1, CatanRules.publicVictoryPoints(s)[0])
+        s = CatanRules.applyMove(s, 0, dig)
+        assertEquals(Terrain.FIELDS, s.terrains[tile])
+        assertEquals(number, s.numbers[tile])
+        assertTrue(CatanRules.legalMoves(s, 0).none { it is DigCanal && it.hex == dig.hex })
+    }
+}

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

@@ -0,0 +1,266 @@
+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.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
+
+/** What every Seafarers map owes the engine, and the shape of each one. */
+class CatanSeaScenariosTest {
+
+    private val json = Json { encodeDefaults = true }
+
+    private fun options(scenario: SeaScenario, players: Int = 3) = CatanOptions(
+        playerCount = players,
+        pointsToWin = 12,
+        expansions = setOf(CatanExpansion.SEAFARERS),
+        scenario = scenario,
+    )
+
+    private fun config(options: CatanOptions, seed: Long) = TableConfig(
+        gameId = GameCatalog.CATAN,
+        seats = (0 until options.playerCount).map {
+            PlayerSlot(seat = it, name = "P$it", kind = PlayerKind.AI, team = it)
+        },
+        optionsJson = json.encodeToString(options),
+        seed = seed,
+    )
+
+    private fun sizes(scenario: SeaScenario): List<Int> {
+        val topo = SeaBoards.topology(scenario)
+        return (0 until topo.islandCount).map { i -> topo.islandOf.count { it == i } }.sorted()
+    }
+
+    @Test
+    fun `each map has the islands it is named for`() {
+        assertEquals(listOf(2, 3, 3, 21), sizes(SeaScenario.NEW_SHORES))
+        assertEquals(listOf(1, 1, 6, 6, 6, 6), sizes(SeaScenario.FOUR_ISLANDS))
+        assertEquals(listOf(1, 1, 1, 2, 25), sizes(SeaScenario.THROUGH_THE_DESERT))
+        assertEquals(listOf(2, 13, 14), sizes(SeaScenario.FOG_ISLANDS))
+        assertEquals(listOf(1, 3, 4, 15), sizes(SeaScenario.TREASURE_ISLANDS))
+        assertEquals(listOf(37), sizes(SeaScenario.OASES))
+        assertEquals(listOf(2, 25), sizes(SeaScenario.GREAT_CANAL))
+        assertEquals(listOf(4, 5, 18), sizes(SeaScenario.PIRATE_ISLANDS))
+        assertEquals(listOf(1, 3, 12, 13), sizes(SeaScenario.WONDERS_OF_CATAN))
+        assertEquals(listOf(2, 3, 6, 17), sizes(SeaScenario.CLOTH_FOR_CATAN))
+        assertEquals(listOf(2, 3, 5, 17), sizes(SeaScenario.FORGOTTEN_TRIBE))
+    }
+
+    @Test
+    fun `every map deals numbers, harbours and a pirate at sea, with the reds apart`() {
+        for (scenario in SeaScenario.entries) {
+            repeat(5) { i ->
+                val s = CatanRules.initialState(config(options(scenario), 300L + i))
+                val topo = s.topo
+                val deserts = s.terrains.count { it == Terrain.DESERT }
+                for (h in 0 until topo.HEX_COUNT) {
+                    val land = s.terrains[h] != Terrain.SEA
+                    assertEquals("$scenario hex $h", topo.land[h], land)
+                    val unnumbered = s.terrains[h] == Terrain.DESERT || s.terrains[h] == Terrain.FOG ||
+                        s.terrains[h] == Terrain.FORTRESS
+                    assertEquals("$scenario hex $h", land && !unnumbered, s.numbers[h] != 0)
+                }
+                val deserted = scenario != SeaScenario.FOUR_ISLANDS && scenario != SeaScenario.CLOTH_FOR_CATAN &&
+                    scenario != SeaScenario.FORGOTTEN_TRIBE && scenario != SeaScenario.PIRATE_ISLANDS &&
+                    scenario != SeaScenario.TREASURE_ISLANDS
+                assertTrue("$scenario has no desert", deserts > 0 || !deserted)
+                // Under fog every hex is face down with no number; the tiles are in the pile.
+                val fog = s.terrains.indices.filter { s.terrains[it] == Terrain.FOG }
+                assertEquals(fog.size, s.sea!!.fogDeck.size)
+                fog.forEach { assertEquals(0, s.numbers[it]) }
+                assertEquals(Terrain.SEA, s.terrains[s.sea!!.pirate])
+                assertEquals("$scenario harbours", 9, s.ports.size)
+                val reds = (0 until topo.HEX_COUNT).filter { s.numbers[it] == 6 || s.numbers[it] == 8 }
+                for (a in reds) for (b in reds) if (a < b) assertFalse("$scenario reds touch", topo.hexesAdjacent(a, b))
+                assertEquals(scenario, s.sea!!.scenario)
+            }
+        }
+    }
+
+    @Test
+    fun `four islands start on any main island and the islets earn the bonus`() {
+        val s = CatanRules.initialState(config(options(SeaScenario.FOUR_ISLANDS), 5L))
+        val sea = s.sea!!
+        assertEquals(4, sea.starts.size)
+        val moves = CatanRules.legalMoves(s, s.firstSeat).filterIsInstance<SetupPlace>()
+        assertEquals(sea.starts.toSet(), moves.map { s.topo.vertexIsland[it.vertex] }.toSet())
+        for (island in 0 until s.topo.islandCount) assertEquals(island in sea.starts, sea.isStart(island))
+        // A settlement on a starting island scores no first-landing bonus.
+        val onMain = (0 until s.topo.VERTEX_COUNT).first { s.topo.vertexIsland[it] == sea.starts.first() }
+        assertEquals(s, SeaRules.claimIsland(s, 0, onMain))
+        val islet = (0 until s.topo.VERTEX_COUNT).first { s.topo.vertexIsland[it] >= 0 && s.topo.vertexIsland[it] !in sea.starts }
+        assertEquals(0, SeaRules.bonusPoints(s, 0))
+        assertEquals(0, SeaRules.bonusPoints(SeaRules.claimIsland(s, 0, onMain), 0))
+        assertEquals(SeaRules.ISLAND_BONUS, SeaRules.bonusPoints(SeaRules.claimIsland(s, 0, islet), 0))
+    }
+
+    @Test
+    fun `through the desert starts everyone on the one big island`() {
+        val s = CatanRules.initialState(config(options(SeaScenario.THROUGH_THE_DESERT), 5L))
+        assertEquals(listOf(s.sea!!.home), s.sea!!.starts)
+        assertEquals(25, s.topo.islandOf.count { it == s.sea!!.home })
+        assertTrue(s.terrains.count { it == Terrain.DESERT } >= 5)
+    }
+
+    @Test
+    fun `a save from before there were several starts still starts on the home island`() {
+        val s = CatanRules.initialState(config(options(SeaScenario.NEW_SHORES), 5L))
+        val old = s.copy(sea = s.sea!!.copy(starts = emptyList()))
+        assertTrue(old.sea!!.isStart(old.sea!!.home))
+        val moves = CatanRules.legalMoves(old, old.firstSeat).filterIsInstance<SetupPlace>()
+        assertTrue(moves.all { old.topo.vertexIsland[it.vertex] == old.sea!!.home })
+    }
+
+    private fun fogGame(seed: Long = 5L) = CatanRules.initialState(config(options(SeaScenario.FOG_ISLANDS), seed)).let {
+        it.copy(phase = CatanPhase.PLAYING, turn = 0, turnNumber = 1, setupIndex = 6)
+    }
+
+    /** A town site on the home island, ships already laid toward the fog, and the one edge that will reach it. */
+    private data class FogRoute(val town: Int, val laid: List<Int>, val last: Int)
+
+    private fun CatanState.fogRoute(): FogRoute {
+        val topo = topo
+        fun touchesFog(v: Int) = topo.VERTEX_HEXES[v].any { terrains[it] == Terrain.FOG }
+        val seen = mutableSetOf<Int>()
+        for (start in 0 until topo.VERTEX_COUNT) {
+            if (topo.vertexIsland[start] != sea!!.home || touchesFog(start)) continue
+            if (topo.VERTEX_EDGES[start].none { topo.edgeSea[it] && !topo.edgeLand[it] }) continue
+            val queue = ArrayDeque<Pair<Int, List<Int>>>().apply { add(start to emptyList()) }
+            seen.clear()
+            while (queue.isNotEmpty()) {
+                val (v, path) = queue.removeFirst()
+                if (!seen.add(v)) continue
+                for (e in topo.VERTEX_EDGES[v]) {
+                    if (!topo.edgeSea[e] || topo.edgeLand[e]) continue
+                    val far = topo.otherEnd(e, v)
+                    if (touchesFog(far)) return FogRoute(start, path, e)
+                    if (path.size < 6) queue.add(far to path + e)
+                }
+            }
+        }
+        error("no ship route from home reaches the fog")
+    }
+
+    /** [fogRoute] laid on the board: the town and all but the last ship. */
+    private fun CatanState.onTheShore(route: FogRoute): CatanState = copy(
+        buildings = buildings.toMutableList().also { it[route.town] = CatanBuilding(BuildingType.SETTLEMENT, 0) },
+        sea = sea!!.copy(ships = sea!!.ships.toMutableList().also { l -> route.laid.forEach { l[it] = 0 } }),
+        resources = List(3) { Resource.entries.associateWith { 3 } },
+    )
+
+    @Test
+    fun `fog is hidden at the start, never a place to begin, and keeps the robber off`() {
+        val s = CatanRules.initialState(config(options(SeaScenario.FOG_ISLANDS), 5L))
+        assertFalse(s.sea!!.isStart(s.topo.islandOf.indices.first { s.terrains[it] == Terrain.FOG }.let { s.topo.islandOf[it] }))
+        val moves = CatanRules.legalMoves(s, s.firstSeat).filterIsInstance<SetupPlace>()
+        assertTrue(moves.all { m -> s.topo.VERTEX_HEXES[m.vertex].none { s.terrains[it] == Terrain.FOG } })
+        val robbing = fogGame().copy(phase = CatanPhase.ROBBER)
+        val targets = CatanRules.legalMoves(robbing, 0).filterIsInstance<MoveRobber>()
+        assertTrue(targets.isNotEmpty())
+        assertTrue(targets.none { robbing.terrains[robbing.topo.hexIndex.getValue(it.hex)] == Terrain.FOG })
+    }
+
+    @Test
+    fun `a ship that reaches the fog turns the hex over and the finder takes a card`() {
+        val base = fogGame()
+        val route = base.fogRoute()
+        val edge = route.last
+        val s = base.onTheShore(route)
+        val tile = s.sea!!.fogDeck.first()
+        val after = CatanRules.applyMove(s, 0, BuildShip(edge))
+        val found = s.topo.EDGE_VERTICES[edge].toList().flatMap { s.topo.VERTEX_HEXES[it] }
+            .filter { s.terrains[it] == Terrain.FOG }.distinct().sorted()
+        val hex = found.first()
+        assertEquals(tile.terrain, after.terrains[hex])
+        assertEquals(tile.number, after.numbers[hex])
+        assertEquals(s.sea!!.fogDeck.size - found.size, after.sea!!.fogDeck.size)
+        val produced = tile.terrain.produces
+        if (produced != null) assertEquals(s.resources[0].getValue(produced) - (if (produced in SeaRules.SHIP_COST) 1 else 0) + 1,
+            after.resources[0].getValue(produced) - (found.drop(1).count { after.terrains[it].produces == produced }))
+        if (tile.terrain == Terrain.GOLD) assertEquals(CatanPhase.GOLD, after.phase)
+        // The find is public: the log names it.
+        assertTrue(after.log.last { "uncovers" in it }.isNotBlank())
+    }
+
+    @Test
+    fun `a gold find during road building asks for the choice and then goes back to the free roads`() {
+        val base = fogGame()
+        val route = base.fogRoute()
+        val edge = route.last
+        val gold = FogTile(Terrain.GOLD, 6)
+        val shore = base.onTheShore(route)
+        val s = shore.copy(
+            phase = CatanPhase.FREE_ROADS,
+            pendingFreeRoads = 2,
+            sea = shore.sea!!.copy(fogDeck = List(shore.sea!!.fogDeck.size) { gold }),
+        )
+        val after = CatanRules.applyMove(s, 0, BuildShip(edge))
+        assertEquals(CatanPhase.GOLD, after.phase)
+        val pick = CatanRules.legalMoves(after, 0).filterIsInstance<PickGold>().first()
+        val resumed = CatanRules.applyMove(after, 0, pick)
+        assertEquals(CatanPhase.FREE_ROADS, resumed.phase)
+        assertEquals(1, resumed.pendingFreeRoads)
+    }
+
+    @Test
+    fun `other seats do not see the face-down tiles and the state survives its wire format`() {
+        val s = fogGame()
+        assertTrue(s.sea!!.fogDeck.isNotEmpty())
+        assertTrue(CatanRules.viewFor(s, 1).sea!!.fogDeck.isEmpty())
+        assertEquals(s, CatanRules.decodeState(CatanRules.encodeState(s)))
+    }
+
+    @Test
+    fun `engines finish a game on every map at three and four players`() {
+        var fogFound = 0
+        var clothPaid = 0
+        var chipsTaken = 0
+        var fortsTaken = 0
+        var wonderStages = 0
+        var chestsOpened = 0
+        var canalDug = 0
+        for (scenario in SeaScenario.entries) {
+            for ((players, seed) in listOf(3 to 11L, 4 to 12L, 3 to 13L)) {
+                val opts = options(scenario, players)
+                val ai = CatanAi()
+                var state = CatanRules.initialState(config(opts, seed))
+                var moves = 0
+                while (!CatanRules.isFinished(state)) {
+                    assertTrue("$scenario seed $seed ran past the cap; log: ${state.log.takeLast(6)}", moves++ < 20_000)
+                    val seat = CatanRules.currentSeat(state) ?: error("$scenario seed $seed: nobody to move in ${state.phase}")
+                    val legal = CatanRules.legalMoves(state, seat)
+                    assertTrue("$scenario seed $seed: no legal move for $seat in ${state.phase}", legal.isNotEmpty())
+                    val move = ai.chooseMove(state, seat, legal)
+                    assertTrue("$scenario seed $seed: illegal $move", CatanRules.isLegalMove(state, seat, move))
+                    state = CatanRules.applyMove(state, seat, move)
+                }
+                assertEquals("$scenario seed $seed", CatanPhase.GAME_OVER, state.phase)
+                if (scenario == SeaScenario.FOG_ISLANDS) fogFound += 14 - state.sea!!.fogDeck.size
+                if (scenario == SeaScenario.CLOTH_FOR_CATAN) clothPaid += state.sea!!.cloth.sum()
+                if (scenario == SeaScenario.PIRATE_ISLANDS) fortsTaken += state.sea!!.raidPoints.sum() / 2
+                if (scenario == SeaScenario.TREASURE_ISLANDS || scenario == SeaScenario.OASES) {
+                    chestsOpened += state.log.count { "treasure chest" in it }
+                }
+                if (scenario == SeaScenario.GREAT_CANAL) canalDug += state.sea!!.canalDug.sum()
+                if (scenario == SeaScenario.WONDERS_OF_CATAN) wonderStages += state.sea!!.wonders.sum()
+                if (scenario == SeaScenario.FORGOTTEN_TRIBE) {
+                    chipsTaken += 4 - state.sea!!.chips.count { it != TribeChip.NONE }
+                }
+                assertEquals(state, CatanRules.decodeState(CatanRules.encodeState(state)))
+            }
+        }
+        assertTrue("no engine ever uncovered a fog hex", fogFound > 0)
+        assertTrue("no village ever paid cloth", clothPaid > 0)
+        assertTrue("no tribe chip was ever taken", chipsTaken > 0)
+        assertTrue("no fortress ever fell", fortsTaken > 0)
+        assertTrue("no chest was ever opened", chestsOpened > 0)
+        assertTrue("no canal unit was ever dug", canalDug > 0)
+        assertTrue("no wonder stage was ever built", wonderStages > 0)
+    }
+}

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

@@ -17,7 +17,7 @@ class CatanSeafarersTest {
     private val json = Json { encodeDefaults = true }
 
     private fun options(players: Int = 3) =
-        CatanOptions(playerCount = players, pointsToWin = 12, ruleSet = CatanRuleSet.SEAFARERS)
+        CatanOptions(playerCount = players, pointsToWin = 12, expansions = setOf(CatanExpansion.SEAFARERS))
 
     private fun config(options: CatanOptions, seed: Long) = TableConfig(
         gameId = GameCatalog.CATAN,
@@ -96,7 +96,7 @@ class CatanSeafarersTest {
     @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>()
+        val moves = CatanRules.legalMoves(s, s.firstSeat).filterIsInstance<SetupPlace>()
         assertTrue(moves.isNotEmpty())
         assertTrue(moves.all { s.topo.vertexIsland[it.vertex] == s.sea!!.home })
         assertTrue(moves.all { s.topo.edgeLand[it.edge] })

app/src/test/java/org/prolibertate/games/game/checkers/CheckersAiProfileTest.kt

@@ -0,0 +1,40 @@
+package org.prolibertate.games.game.checkers
+
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertTrue
+import org.junit.Test
+import org.prolibertate.games.game.engine.AiDifficulty
+import org.prolibertate.games.game.engine.AiProfiles
+
+class CheckersAiProfileTest {
+
+    @Test
+    fun `every difficulty and seeded style plays only legal moves`() {
+        val seen = mutableSetOf<Pair<Any, Any>>()
+        for (difficulty in AiDifficulty.entries) for (seed in 0L until 12L) {
+            val profiles = AiProfiles(difficulty, seed)
+            for (seat in 0..1) profiles.of(seat).let { seen += it.level to it.style }
+            val ai = CheckersAi(profiles, CheckersLevel.CASUAL)
+            var state = CheckersRules.initialState(CheckersOptions(level = CheckersLevel.CASUAL))
+            var plies = 0
+            while (!CheckersRules.isFinished(state) && plies < 10) {
+                val legal = CheckersRules.legalMoves(state)
+                val move = ai.chooseMove(state, state.turn, legal)
+                assertTrue("$difficulty/$seed illegal move $move", move in legal)
+                state = CheckersRules.applyMove(state, state.turn, move)
+                plies++
+            }
+        }
+        assertTrue("expected a spread of level/style pairs, saw ${seen.size}", seen.size >= 8)
+    }
+
+    @Test
+    fun `default profile plays the same as an explicit medium table`() {
+        val state = CheckersRules.initialState(CheckersOptions(level = CheckersLevel.CASUAL))
+        val legal = CheckersRules.legalMoves(state)
+        val a = CheckersAi(level = CheckersLevel.CASUAL).chooseMove(state, state.turn, legal)
+        val b = CheckersAi(AiProfiles(AiDifficulty.MEDIUM, 5L), CheckersLevel.CASUAL)
+            .chooseMove(state, state.turn, legal)
+        assertEquals(a, b)
+    }
+}

app/src/test/java/org/prolibertate/games/game/chess/ChessAiTest.kt

@@ -3,6 +3,11 @@ package org.prolibertate.games.game.chess
 import org.junit.Assert.assertEquals
 import org.junit.Assert.assertTrue
 import org.junit.Test
+import org.prolibertate.games.game.engine.AiDifficulty
+import org.prolibertate.games.game.engine.AiLevel
+import org.prolibertate.games.game.engine.AiProfile
+import org.prolibertate.games.game.engine.AiProfiles
+import org.prolibertate.games.game.engine.AiStyle
 
 class ChessAiTest {
 
@@ -128,4 +133,52 @@ class ChessAiTest {
             assertTrue("$level took ${millis}ms", millis < 15_000)
         }
     }
+
+    @Test
+    fun `every level and style returns a legal move over a few playouts`() {
+        val opening = "r1bqkb1r/pppp1ppp/2n2n2/4p3/2B1P3/5N2/PPPP1PPP/RNBQK2R w KQkq - 4 4"
+        for (diff in listOf(AiDifficulty.EASY, AiDifficulty.MEDIUM, AiDifficulty.HARD, AiDifficulty.MIXED)) {
+            for (seed in 1L..4L) {
+                val ai = ChessAi(AiProfiles(diff, seed))
+                var state = ChessRules.fromPosition(ChessOptions(level = ChessLevel.CASUAL), opening)
+                repeat(6) {
+                    if (ChessRules.isFinished(state)) return@repeat
+                    val legal = ChessRules.legalMoves(state)
+                    val move = ai.moveIn(state)
+                    assertTrue("$diff/$seed: $move illegal", legal.contains(move))
+                    state = ChessRules.applyMove(state, state.turnSeat, move)
+                }
+            }
+        }
+    }
+
+    @Test
+    fun `easy and every style still take a hanging queen`() {
+        val state = position("3r3k/8/8/3q4/8/8/8/3R2K1 w - - 0 1", ChessLevel.CLUB)
+        for (style in AiStyle.entries) {
+            val ai = ChessAi(AiProfilesFixed(AiLevel.HARD, style))
+            assertEquals("d1d5", ai.moveIn(state).toString())
+        }
+    }
+
+    @Test
+    fun `the default profile matches the no-argument ai`() {
+        val state = position("r1bqkb1r/pppp1ppp/2n2n2/4p3/2B1P3/5N2/PPPP1PPP/RNBQK2R w KQkq - 4 4")
+        assertEquals(ChessAi().moveIn(state), ChessAi(AiProfiles.DEFAULT).moveIn(state))
+    }
+
+    /** Profiles with one fixed level and style for every seat. */
+    private fun AiProfilesFixed(level: AiLevel, style: AiStyle): AiProfiles {
+        val diff = when (level) {
+            AiLevel.EASY -> AiDifficulty.EASY
+            AiLevel.MEDIUM -> AiDifficulty.MEDIUM
+            AiLevel.HARD -> AiDifficulty.HARD
+        }
+        // Search seeds until the derived style matches; the style space is tiny.
+        for (seed in 0L..500L) {
+            val profiles = AiProfiles(diff, seed)
+            if (profiles.of(0).style == style && profiles.of(1).style == style) return profiles
+        }
+        return AiProfiles(diff, 0L)
+    }
 }

app/src/test/java/org/prolibertate/games/game/crazyeights/CrazyEightsAiProfileTest.kt

@@ -0,0 +1,71 @@
+package org.prolibertate.games.game.crazyeights
+
+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.engine.AiDifficulty
+import org.prolibertate.games.game.engine.AiProfiles
+import org.prolibertate.games.game.engine.PlayerKind
+import org.prolibertate.games.game.engine.PlayerSlot
+import org.prolibertate.games.game.engine.TableConfig
+
+class CrazyEightsAiProfileTest {
+
+    private val json = Json { encodeDefaults = true }
+
+    private fun config(options: CrazyEightsOptions, seed: Long) = TableConfig(
+        gameId = "crazy8s",
+        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 play(ai: CrazyEightsAi, options: CrazyEightsOptions, seed: Long): List<CrazyEightsMove> {
+        var state = CrazyEightsRules.initialState(config(options, seed))
+        val moves = mutableListOf<CrazyEightsMove>()
+        var guard = 0
+        while (!CrazyEightsRules.isFinished(state) && guard++ < 6000) {
+            val seat = CrazyEightsRules.currentSeat(state)
+            if (seat == null) {
+                state = CrazyEightsRules.nextRound(state)
+                continue
+            }
+            val legal = CrazyEightsRules.legalMoves(state, seat)
+            val move = ai.chooseMove(state, seat, legal)
+            assertTrue("illegal move $move", legal.contains(move))
+            moves += move
+            state = CrazyEightsRules.applyMove(state, seat, move)
+        }
+        assertTrue("game did not finish", CrazyEightsRules.isFinished(state))
+        return moves
+    }
+
+    @Test
+    fun `every difficulty and style plays complete games legally`() {
+        val variants = listOf(
+            CrazyEightsOptions(playerCount = 4, roundsToPlay = 2),
+            CrazyEightsOptions(playerCount = 2, roundsToPlay = 2, drawUntilPlayable = false),
+            CrazyEightsOptions(playerCount = 6, roundsToPlay = 2),
+        )
+        for (difficulty in listOf(AiDifficulty.EASY, AiDifficulty.HARD, AiDifficulty.MIXED)) {
+            for (seed in 0L until 9L) {
+                val options = variants[(seed % variants.size).toInt()]
+                play(CrazyEightsAi(AiProfiles(difficulty, seed)), options, 300L + seed)
+            }
+        }
+    }
+
+    @Test
+    fun `the default profile plays like a medium balanced seat`() {
+        val options = CrazyEightsOptions(playerCount = 4, roundsToPlay = 2)
+        for (seed in 1L..3L) {
+            val default = play(CrazyEightsAi(), options, seed)
+            val medium = play(CrazyEightsAi(AiProfiles(AiDifficulty.MEDIUM, 31L + seed)), options, seed)
+            assertEquals(default, medium)
+        }
+    }
+}

app/src/test/java/org/prolibertate/games/game/cribbage/CribbageAiLevelsTest.kt

@@ -0,0 +1,101 @@
+package org.prolibertate.games.game.cribbage
+
+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.engine.AiDifficulty
+import org.prolibertate.games.game.engine.AiProfiles
+import org.prolibertate.games.game.engine.AiStyle
+import org.prolibertate.games.game.engine.PlayerKind
+import org.prolibertate.games.game.engine.PlayerSlot
+import org.prolibertate.games.game.engine.TableConfig
+
+class CribbageAiLevelsTest {
+
+    private val json = Json { encodeDefaults = true }
+
+    private fun config(options: CribbageOptions, seed: Long) = TableConfig(
+        gameId = "cribbage",
+        seats = (0 until options.playerCount).map {
+            PlayerSlot(seat = it, name = "P$it", kind = PlayerKind.AI, team = options.teamOf(it))
+        },
+        optionsJson = json.encodeToString(options),
+        seed = seed,
+    )
+
+    /** Seeds that between them give some seat every style at this difficulty. */
+    private fun seedsCoveringStyles(difficulty: AiDifficulty, seats: Int): List<Long> {
+        // The standard opponent is balanced by definition, so there is no style to cover.
+        if (difficulty == AiDifficulty.MEDIUM) return listOf(0L, 1L, 2L)
+        val missing = AiStyle.entries.toMutableSet()
+        val seeds = mutableListOf<Long>()
+        var seed = 0L
+        while (missing.isNotEmpty() && seed < 500) {
+            val styles = (0 until seats).map { AiProfiles(difficulty, seed).of(it).style }
+            if (styles.any { it in missing }) {
+                seeds += seed
+                missing.removeAll(styles.toSet())
+            }
+            seed++
+        }
+        assertTrue("styles never covered: $missing", missing.isEmpty())
+        return seeds
+    }
+
+    /** Plays a whole game with [ai] in every seat; returns the moves chosen. */
+    private fun play(ai: CribbageAi, options: CribbageOptions, seed: Long): List<CribbageMove> {
+        var state = CribbageRules.initialState(config(options, seed))
+        val moves = mutableListOf<CribbageMove>()
+        var guard = 0
+        while (!CribbageRules.isFinished(state) && guard++ < 20000) {
+            val seat = CribbageRules.currentSeat(state)
+            if (seat == null) {
+                state = CribbageRules.nextHand(state)
+                continue
+            }
+            val legal = CribbageRules.legalMoves(state, seat)
+            val move = ai.chooseMove(state, seat, legal)
+            assertTrue("illegal move $move", legal.contains(move))
+            moves += move
+            state = CribbageRules.applyMove(state, seat, move)
+        }
+        assertTrue("game ran away", guard < 20000)
+        return moves
+    }
+
+    @Test
+    fun `every level and style plays a whole game legally`() {
+        val options = CribbageOptions(pointsToWin = 61)
+        listOf(AiDifficulty.EASY, AiDifficulty.MEDIUM, AiDifficulty.HARD).forEach { difficulty ->
+            seedsCoveringStyles(difficulty, options.playerCount).forEach { seed ->
+                play(CribbageAi(AiProfiles(difficulty, seed)), options, 100L + seed)
+            }
+        }
+    }
+
+    @Test
+    fun `a four handed table plays legally at every level`() {
+        val options = CribbageOptions(playerCount = 4, pointsToWin = 61)
+        listOf(AiDifficulty.EASY, AiDifficulty.HARD, AiDifficulty.MIXED).forEach { difficulty ->
+            play(CribbageAi(AiProfiles(difficulty, 3L)), options, 7L)
+        }
+    }
+
+    @Test
+    fun `the default profile plays as the standard opponent`() {
+        val options = CribbageOptions(pointsToWin = 61)
+        val standard = play(CribbageAi(), options, 55L)
+        val medium = play(CribbageAi(AiProfiles(AiDifficulty.MEDIUM, 9L)), options, 55L)
+        assertEquals(standard, medium)
+    }
+
+    @Test
+    fun `easy does not always play the best card`() {
+        val options = CribbageOptions(pointsToWin = 61)
+        val standard = play(CribbageAi(), options, 55L)
+        val easy = play(CribbageAi(AiProfiles(AiDifficulty.EASY, 9L)), options, 55L)
+        assertTrue("easy played exactly like medium", standard != easy)
+    }
+}

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

@@ -0,0 +1,77 @@
+package org.prolibertate.games.game.engine
+
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertFalse
+import org.junit.Assert.assertTrue
+import org.junit.Test
+
+class AiProfilesTest {
+
+    @Test
+    fun `fixed difficulties give every seat that level`() {
+        for ((difficulty, level) in listOf(
+            AiDifficulty.EASY to AiLevel.EASY,
+            AiDifficulty.MEDIUM to AiLevel.MEDIUM,
+            AiDifficulty.HARD to AiLevel.HARD,
+        )) {
+            val profiles = AiProfiles(difficulty, seed = 42)
+            for (seat in 0..5) assertEquals(level, profiles.of(seat).level)
+        }
+    }
+
+    @Test
+    fun `medium is the balanced standard opponent and never slips`() {
+        val profiles = AiProfiles(AiDifficulty.MEDIUM, seed = 7)
+        for (seat in 0..5) {
+            val profile = profiles.of(seat)
+            assertEquals(AiStyle.BALANCED, profile.style)
+            repeat(200) { assertFalse(profile.slips()) }
+        }
+    }
+
+    @Test
+    fun `the same table always gives a seat the same personality`() {
+        val a = AiProfiles(AiDifficulty.MIXED, seed = 1234)
+        val b = AiProfiles(AiDifficulty.MIXED, seed = 1234)
+        for (seat in 0..6) {
+            assertEquals(a.of(seat).level, b.of(seat).level)
+            assertEquals(a.of(seat).style, b.of(seat).style)
+        }
+    }
+
+    @Test
+    fun `mixed tables vary by seat and across seeds`() {
+        val seen = (0L..200L).flatMap { seed ->
+            val profiles = AiProfiles(AiDifficulty.MIXED, seed)
+            (0..3).map { profiles.of(it).level to profiles.of(it).style }
+        }.toSet()
+        assertTrue(seen.map { it.first }.toSet() == AiLevel.entries.toSet())
+        assertTrue(seen.map { it.second }.toSet() == AiStyle.entries.toSet())
+    }
+
+    @Test
+    fun `only easy slips, and not every time`() {
+        val easy = AiProfiles(AiDifficulty.EASY, 1).of(0)
+        val slips = (1..1000).count { easy.slips() }
+        assertTrue("slipped $slips of 1000", slips in 200..400)
+        val hard = AiProfiles(AiDifficulty.HARD, 1).of(0)
+        repeat(200) { assertFalse(hard.slips()) }
+    }
+
+    @Test
+    fun `pick takes the best unless easy slips and then stays in the better half`() {
+        val ranked = (1..10).toList()
+        assertEquals(1, AiProfiles(AiDifficulty.HARD, 3).of(0).pick(ranked))
+        val easy = AiProfiles(AiDifficulty.EASY, 3).of(0)
+        val picks = (1..500).map { easy.pick(ranked) }
+        assertTrue(picks.all { it <= 5 })
+        assertTrue(picks.toSet().size > 1)
+    }
+
+    @Test
+    fun `a config without a difficulty reads as medium`() {
+        val config = TableConfig("chess", emptyList(), "{}", 1L)
+        assertEquals(AiDifficulty.MEDIUM, config.aiDifficulty)
+        assertEquals(AiLevel.MEDIUM, AiProfiles(config).of(0).level)
+    }
+}

app/src/test/java/org/prolibertate/games/game/euchre/EuchreAiProfilesTest.kt

@@ -0,0 +1,65 @@
+package org.prolibertate.games.game.euchre
+
+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.engine.AiDifficulty
+import org.prolibertate.games.game.engine.AiProfiles
+import org.prolibertate.games.game.engine.PlayerKind
+import org.prolibertate.games.game.engine.PlayerSlot
+import org.prolibertate.games.game.engine.TableConfig
+
+class EuchreAiProfilesTest {
+
+    private val json = Json { encodeDefaults = true }
+
+    private fun config(seed: Long) = TableConfig(
+        gameId = "euchre",
+        seats = (0 until 4).map {
+            PlayerSlot(seat = it, name = "P$it", kind = PlayerKind.AI, team = it % 2)
+        },
+        optionsJson = json.encodeToString(EuchreOptions(pointsToWin = 4)),
+        seed = seed,
+    )
+
+    /** Plays a whole game with every seat on [ai], returning every move chosen. */
+    private fun playGame(ai: EuchreAi, seed: Long): List<EuchreMove> {
+        val moves = mutableListOf<EuchreMove>()
+        var state = EuchreRules.initialState(config(seed))
+        var guard = 0
+        while (!EuchreRules.isFinished(state) && guard++ < 3000) {
+            val seat = EuchreRules.currentSeat(state)
+            if (seat == null) {
+                state = EuchreRules.nextHand(state)
+                continue
+            }
+            val legal = EuchreRules.legalMoves(state, seat)
+            val move = ai.chooseMove(state, seat, legal)
+            assertTrue("illegal move $move in ${state.phase}", legal.contains(move))
+            moves += move
+            state = EuchreRules.applyMove(state, seat, move)
+        }
+        assertTrue("game with seed $seed did not finish", EuchreRules.isFinished(state))
+        return moves
+    }
+
+    @Test
+    fun `every difficulty and style plays whole games legally`() {
+        for (difficulty in AiDifficulty.entries) {
+            for (seed in 1L..8L) {
+                playGame(EuchreAi(AiProfiles(difficulty, seed)), seed)
+            }
+        }
+    }
+
+    @Test
+    fun `the default profile plays as a medium balanced seat`() {
+        for (seed in 1L..3L) {
+            val standard = playGame(EuchreAi(), seed)
+            val explicit = playGame(EuchreAi(AiProfiles(AiDifficulty.MEDIUM, 99L)), seed)
+            assertEquals(standard, explicit)
+        }
+    }
+}

app/src/test/java/org/prolibertate/games/game/golf/GolfAiProfileTest.kt

@@ -0,0 +1,72 @@
+package org.prolibertate.games.game.golf
+
+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.engine.AiDifficulty
+import org.prolibertate.games.game.engine.AiProfiles
+import org.prolibertate.games.game.engine.PlayerKind
+import org.prolibertate.games.game.engine.PlayerSlot
+import org.prolibertate.games.game.engine.TableConfig
+
+class GolfAiProfileTest {
+
+    private val json = Json { encodeDefaults = true }
+
+    private fun config(options: GolfOptions, seed: Long) = TableConfig(
+        gameId = "golf",
+        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 play(ai: GolfAi, options: GolfOptions, seed: Long): List<GolfMove> {
+        var state = GolfRules.initialState(config(options, seed))
+        val moves = mutableListOf<GolfMove>()
+        var guard = 0
+        while (!GolfRules.isFinished(state) && guard++ < 8000) {
+            val seat = GolfRules.currentSeat(state)
+            if (seat == null) {
+                state = GolfRules.nextHole(state)
+                continue
+            }
+            val legal = GolfRules.legalMoves(state, seat)
+            val move = ai.chooseMove(state, seat, legal)
+            assertTrue("illegal move $move", legal.contains(move))
+            moves += move
+            state = GolfRules.applyMove(state, seat, move)
+        }
+        assertTrue("game did not finish", GolfRules.isFinished(state))
+        return moves
+    }
+
+    @Test
+    fun `every difficulty and style plays complete games legally`() {
+        val variants = listOf(
+            GolfOptions(playerCount = 2, gridSize = 6, holes = 2),
+            GolfOptions(playerCount = 4, gridSize = 9, holes = 2),
+            GolfOptions(playerCount = 3, gridSize = 4, holes = 2, lineUpFinalPutt = true),
+            GolfOptions(playerCount = 6, gridSize = 8, holes = 1),
+        )
+        for (difficulty in listOf(AiDifficulty.EASY, AiDifficulty.HARD, AiDifficulty.MIXED)) {
+            for (seed in 0L until 8L) {
+                val options = variants[(seed % variants.size).toInt()]
+                play(GolfAi(AiProfiles(difficulty, seed)), options, 400L + seed)
+            }
+        }
+    }
+
+    @Test
+    fun `the default profile plays like a medium balanced seat`() {
+        val options = GolfOptions(playerCount = 3, gridSize = 6, holes = 2)
+        for (seed in 1L..3L) {
+            val default = play(GolfAi(), options, seed)
+            val medium = play(GolfAi(AiProfiles(AiDifficulty.MEDIUM, 13L + seed)), options, seed)
+            assertEquals(default, medium)
+        }
+    }
+}

app/src/test/java/org/prolibertate/games/game/hearts/HeartsAiProfileTest.kt

@@ -0,0 +1,63 @@
+package org.prolibertate.games.game.hearts
+
+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.engine.AiDifficulty
+import org.prolibertate.games.game.engine.AiProfiles
+import org.prolibertate.games.game.engine.PlayerKind
+import org.prolibertate.games.game.engine.PlayerSlot
+import org.prolibertate.games.game.engine.TableConfig
+
+class HeartsAiProfileTest {
+
+    private val json = Json { encodeDefaults = true }
+
+    private fun config(seed: Long) = TableConfig(
+        gameId = "hearts",
+        seats = (0 until 4).map { PlayerSlot(seat = it, name = "P$it", kind = PlayerKind.AI, team = it) },
+        optionsJson = json.encodeToString(HeartsOptions(targetScore = 50)),
+        seed = seed,
+    )
+
+    /** Plays a whole game and returns every move made, asserting each was legal. */
+    private fun play(ai: HeartsAi, seed: Long): List<HeartsMove> {
+        var state = HeartsRules.initialState(config(seed))
+        val moves = mutableListOf<HeartsMove>()
+        var guard = 0
+        while (!HeartsRules.isFinished(state) && guard++ < 5000) {
+            val seat = HeartsRules.currentSeat(state)
+            if (seat == null) {
+                state = HeartsRules.startNextRound(state)
+                continue
+            }
+            val legal = HeartsRules.legalMoves(state, seat)
+            val move = ai.chooseMove(state, seat, legal)
+            assertTrue("illegal move $move", legal.contains(move))
+            moves += move
+            state = HeartsRules.applyMove(state, seat, move)
+        }
+        assertTrue("game did not finish", HeartsRules.isFinished(state))
+        return moves
+    }
+
+    @Test
+    fun `every difficulty and style plays complete games legally`() {
+        for (difficulty in listOf(AiDifficulty.EASY, AiDifficulty.HARD, AiDifficulty.MIXED)) {
+            for (seed in 0L until 8L) {
+                play(HeartsAi(AiProfiles(difficulty, seed)), 100L + seed)
+            }
+        }
+    }
+
+    @Test
+    fun `the default profile plays like a medium balanced seat`() {
+        for (seed in 1L..3L) {
+            val default = play(HeartsAi(), seed)
+            val medium = play(HeartsAi(AiProfiles(AiDifficulty.MEDIUM, 77L + seed)), seed)
+            assertEquals(default, medium)
+        }
+    }
+}

app/src/test/java/org/prolibertate/games/game/kaiser/KaiserAiProfilesTest.kt

@@ -0,0 +1,68 @@
+package org.prolibertate.games.game.kaiser
+
+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.engine.AiDifficulty
+import org.prolibertate.games.game.engine.AiProfiles
+import org.prolibertate.games.game.engine.PlayerKind
+import org.prolibertate.games.game.engine.PlayerSlot
+import org.prolibertate.games.game.engine.TableConfig
+
+class KaiserAiProfilesTest {
+
+    private val json = Json { encodeDefaults = true }
+
+    private fun config(seed: Long) = TableConfig(
+        gameId = "kaiser",
+        seats = (0 until 4).map {
+            PlayerSlot(seat = it, name = "P$it", kind = PlayerKind.AI, team = it % 2)
+        },
+        optionsJson = json.encodeToString(KaiserOptions()),
+        seed = seed,
+    )
+
+    /** Plays up to [hands] hands with every seat on [ai], returning every move chosen. */
+    private fun playHands(ai: KaiserAi, seed: Long, hands: Int): List<KaiserMove> {
+        val moves = mutableListOf<KaiserMove>()
+        var state = KaiserRules.initialState(config(seed))
+        var dealt = 1
+        var guard = 0
+        while (!KaiserRules.isFinished(state) && guard++ < 4000) {
+            val seat = KaiserRules.currentSeat(state)
+            if (seat == null) {
+                if (dealt >= hands) break
+                dealt++
+                state = KaiserRules.nextHand(state)
+                continue
+            }
+            val legal = KaiserRules.legalMoves(state, seat)
+            val move = ai.chooseMove(state, seat, legal)
+            assertTrue("illegal move $move in ${state.phase}", legal.contains(move))
+            moves += move
+            state = KaiserRules.applyMove(state, seat, move)
+        }
+        return moves
+    }
+
+    @Test
+    fun `every difficulty and style plays hands legally`() {
+        for (difficulty in AiDifficulty.entries) {
+            for (seed in 1L..8L) {
+                val moves = playHands(KaiserAi(AiProfiles(difficulty, seed)), seed, hands = 4)
+                assertTrue(moves.isNotEmpty())
+            }
+        }
+    }
+
+    @Test
+    fun `the default profile plays as a medium balanced seat`() {
+        for (seed in 1L..3L) {
+            val standard = playHands(KaiserAi(), seed, hands = 3)
+            val explicit = playHands(KaiserAi(AiProfiles(AiDifficulty.MEDIUM, 99L)), seed, hands = 3)
+            assertEquals(standard, explicit)
+        }
+    }
+}

app/src/test/java/org/prolibertate/games/game/morris/MorrisAiProfileTest.kt

@@ -0,0 +1,40 @@
+package org.prolibertate.games.game.morris
+
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertTrue
+import org.junit.Test
+import org.prolibertate.games.game.engine.AiDifficulty
+import org.prolibertate.games.game.engine.AiProfiles
+
+class MorrisAiProfileTest {
+
+    @Test
+    fun `every difficulty and seeded style plays only legal moves`() {
+        val seen = mutableSetOf<Pair<Any, Any>>()
+        for (difficulty in AiDifficulty.entries) for (seed in 0L until 12L) {
+            val profiles = AiProfiles(difficulty, seed)
+            for (seat in 0..1) profiles.of(seat).let { seen += it.level to it.style }
+            val ai = MorrisAi(profiles, MorrisLevel.CASUAL)
+            var state = MorrisRules.initialState(MorrisOptions(level = MorrisLevel.CASUAL))
+            var plies = 0
+            while (!MorrisRules.isFinished(state) && plies < 8) {
+                val legal = MorrisRules.legalMoves(state)
+                val move = ai.chooseMove(state, state.turn, legal)
+                assertTrue("$difficulty/$seed illegal move $move", move in legal)
+                state = MorrisRules.applyMove(state, state.turn, move)
+                plies++
+            }
+        }
+        assertTrue("expected a spread of level/style pairs, saw ${seen.size}", seen.size >= 8)
+    }
+
+    @Test
+    fun `default profile plays the same as an explicit medium table`() {
+        val state = MorrisRules.initialState(MorrisOptions(level = MorrisLevel.CASUAL))
+        val legal = MorrisRules.legalMoves(state)
+        val a = MorrisAi(level = MorrisLevel.CASUAL).chooseMove(state, state.turn, legal)
+        val b = MorrisAi(AiProfiles(AiDifficulty.MEDIUM, 5L), MorrisLevel.CASUAL)
+            .chooseMove(state, state.turn, legal)
+        assertEquals(a, b)
+    }
+}

app/src/test/java/org/prolibertate/games/game/morris/MorrisAiTest.kt

@@ -29,7 +29,7 @@ class MorrisAiTest {
     )
 
     private fun choose(state: MorrisState, level: MorrisLevel = MorrisLevel.CLUB): MorrisMove =
-        MorrisAi(level).chooseMove(state, state.turn, MorrisRules.legalMoves(state))
+        MorrisAi(level = level).chooseMove(state, state.turn, MorrisRules.legalMoves(state))
 
     @Test
     fun `it always returns a move it is allowed to play`() {

app/src/test/java/org/prolibertate/games/game/pirates/PiratesAiProfileTest.kt

@@ -0,0 +1,45 @@
+package org.prolibertate.games.game.pirates
+
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertTrue
+import org.junit.Test
+import org.prolibertate.games.game.engine.AiDifficulty
+import org.prolibertate.games.game.engine.AiProfiles
+
+class PiratesAiProfileTest {
+
+    private fun playout(ai: PiratesAi, steps: Int): List<PiratesMove> {
+        var state = PiratesRules.initialState(PiratesOptions(level = PiratesLevel.CASUAL))
+        val chosen = mutableListOf<PiratesMove>()
+        repeat(steps) {
+            if (PiratesRules.isFinished(state)) return chosen
+            val seat = PiratesRules.currentSeat(state) ?: return chosen
+            val legal = PiratesRules.legalMoves(state, seat)
+            if (legal.isEmpty()) return chosen
+            val move = ai.chooseMove(state, seat, legal)
+            assertTrue("illegal move $move", move in legal)
+            chosen += move
+            state = PiratesRules.applyMove(state, seat, move)
+        }
+        return chosen
+    }
+
+    @Test
+    fun everyLevelAndStyleReturnsLegalMoves() {
+        for (difficulty in listOf(AiDifficulty.EASY, AiDifficulty.MEDIUM, AiDifficulty.MIXED)) {
+            for (seed in 0L..5L) {
+                assertTrue(playout(PiratesAi(AiProfiles(difficulty, seed)), 12).isNotEmpty())
+            }
+        }
+        for (seed in 0L..3L) {
+            assertTrue(playout(PiratesAi(AiProfiles(AiDifficulty.HARD, seed)), 4).isNotEmpty())
+        }
+    }
+
+    @Test
+    fun defaultProfilePlaysAsBefore() {
+        val plain = playout(PiratesAi(), 10)
+        val medium = playout(PiratesAi(AiProfiles(AiDifficulty.MEDIUM, 77L)), 10)
+        assertEquals(plain, medium)
+    }
+}

app/src/test/java/org/prolibertate/games/game/president/PresidentAiProfileTest.kt

@@ -0,0 +1,71 @@
+package org.prolibertate.games.game.president
+
+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.engine.AiDifficulty
+import org.prolibertate.games.game.engine.AiProfiles
+import org.prolibertate.games.game.engine.PlayerKind
+import org.prolibertate.games.game.engine.PlayerSlot
+import org.prolibertate.games.game.engine.TableConfig
+
+class PresidentAiProfileTest {
+
+    private val json = Json { encodeDefaults = true }
+
+    private fun config(options: PresidentOptions, seed: Long) = TableConfig(
+        gameId = "president",
+        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 play(ai: PresidentAi, options: PresidentOptions, seed: Long): List<PresidentMove> {
+        var state = PresidentRules.initialState(config(options, seed))
+        val moves = mutableListOf<PresidentMove>()
+        var guard = 0
+        while (!PresidentRules.isFinished(state) && guard++ < 6000) {
+            val seat = PresidentRules.currentSeat(state)
+            if (seat == null) {
+                state = PresidentRules.nextRound(state)
+                continue
+            }
+            val legal = PresidentRules.legalMoves(state, seat)
+            val move = ai.chooseMove(state, seat, legal)
+            assertTrue("illegal move $move", legal.contains(move))
+            moves += move
+            state = PresidentRules.applyMove(state, seat, move)
+        }
+        assertTrue("game did not finish", PresidentRules.isFinished(state))
+        return moves
+    }
+
+    @Test
+    fun `every difficulty and style plays complete games legally`() {
+        val variants = listOf(
+            PresidentOptions(playerCount = 4, roundsToPlay = 3),
+            PresidentOptions(playerCount = 5, roundsToPlay = 2, fourOfAKindBomb = true),
+            PresidentOptions(playerCount = 3, roundsToPlay = 2, twosClear = false),
+        )
+        for (difficulty in listOf(AiDifficulty.EASY, AiDifficulty.HARD, AiDifficulty.MIXED)) {
+            for (seed in 0L until 6L) {
+                val options = variants[(seed % variants.size).toInt()]
+                play(PresidentAi(AiProfiles(difficulty, seed)), options, 200L + seed)
+            }
+        }
+    }
+
+    @Test
+    fun `the default profile plays like a medium balanced seat`() {
+        val options = PresidentOptions(playerCount = 4, roundsToPlay = 2)
+        for (seed in 1L..3L) {
+            val default = play(PresidentAi(), options, seed)
+            val medium = play(PresidentAi(AiProfiles(AiDifficulty.MEDIUM, 55L + seed)), options, seed)
+            assertEquals(default, medium)
+        }
+    }
+}

app/src/test/java/org/prolibertate/games/game/sequence/SequenceAiLevelsTest.kt

@@ -0,0 +1,89 @@
+package org.prolibertate.games.game.sequence
+
+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.engine.AiDifficulty
+import org.prolibertate.games.game.engine.AiProfiles
+import org.prolibertate.games.game.engine.AiStyle
+import org.prolibertate.games.game.engine.PlayerKind
+import org.prolibertate.games.game.engine.PlayerSlot
+import org.prolibertate.games.game.engine.TableConfig
+
+class SequenceAiLevelsTest {
+
+    private val json = Json { encodeDefaults = true }
+
+    private fun config(options: SequenceOptions, seed: Long) = TableConfig(
+        gameId = "sequence",
+        seats = (0 until options.playerCount).map {
+            PlayerSlot(seat = it, name = "P$it", kind = PlayerKind.AI, team = it % options.teamCount)
+        },
+        optionsJson = json.encodeToString(options),
+        seed = seed,
+    )
+
+    /** Seeds that between them give some seat every style at this difficulty. */
+    private fun seedsCoveringStyles(difficulty: AiDifficulty, seats: Int): List<Long> {
+        // The standard opponent is balanced by definition, so there is no style to cover.
+        if (difficulty == AiDifficulty.MEDIUM) return listOf(0L, 1L, 2L)
+        val missing = AiStyle.entries.toMutableSet()
+        val seeds = mutableListOf<Long>()
+        var seed = 0L
+        while (missing.isNotEmpty() && seed < 500) {
+            val styles = (0 until seats).map { AiProfiles(difficulty, seed).of(it).style }
+            if (styles.any { it in missing }) {
+                seeds += seed
+                missing.removeAll(styles.toSet())
+            }
+            seed++
+        }
+        assertTrue("styles never covered: $missing", missing.isEmpty())
+        return seeds
+    }
+
+    private fun play(ai: SequenceAi, options: SequenceOptions, seed: Long): List<SequenceMove> {
+        var state = SequenceRules.initialState(config(options, seed))
+        val moves = mutableListOf<SequenceMove>()
+        var guard = 0
+        while (!SequenceRules.isFinished(state) && guard++ < 4000) {
+            val seat = SequenceRules.currentSeat(state) ?: break
+            val legal = SequenceRules.legalMoves(state, seat)
+            if (legal.isEmpty()) break
+            val move = ai.chooseMove(state, seat, legal)
+            assertTrue("illegal move $move", legal.contains(move))
+            moves += move
+            state = SequenceRules.applyMove(state, seat, move)
+        }
+        assertTrue("game ran away", guard < 4000)
+        return moves
+    }
+
+    @Test
+    fun `every level and style plays a whole game legally`() {
+        val options = SequenceOptions(teamCount = 2, playersPerTeam = 1)
+        listOf(AiDifficulty.EASY, AiDifficulty.MEDIUM, AiDifficulty.HARD).forEach { difficulty ->
+            seedsCoveringStyles(difficulty, options.playerCount).forEach { seed ->
+                play(SequenceAi(AiProfiles(difficulty, seed)), options, 300L + seed)
+            }
+        }
+    }
+
+    @Test
+    fun `three teams play legally at every level`() {
+        val options = SequenceOptions(teamCount = 3, playersPerTeam = 1, sequencesToWin = 1)
+        listOf(AiDifficulty.EASY, AiDifficulty.HARD, AiDifficulty.MIXED).forEach { difficulty ->
+            play(SequenceAi(AiProfiles(difficulty, 4L)), options, 11L)
+        }
+    }
+
+    @Test
+    fun `the default profile plays as the standard opponent`() {
+        val options = SequenceOptions()
+        val standard = play(SequenceAi(), options, 21L)
+        val medium = play(SequenceAi(AiProfiles(AiDifficulty.MEDIUM, 6L)), options, 21L)
+        assertEquals(standard, medium)
+    }
+}

app/src/test/java/org/prolibertate/games/game/tayu/TayuAiLevelsTest.kt

@@ -0,0 +1,88 @@
+package org.prolibertate.games.game.tayu
+
+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.engine.AiDifficulty
+import org.prolibertate.games.game.engine.AiProfiles
+import org.prolibertate.games.game.engine.AiStyle
+import org.prolibertate.games.game.engine.PlayerKind
+import org.prolibertate.games.game.engine.PlayerSlot
+import org.prolibertate.games.game.engine.TableConfig
+
+class TayuAiLevelsTest {
+
+    private val json = Json { encodeDefaults = true }
+
+    private val options = TayuOptions(tileCopies = 2)
+
+    private fun config(seed: Long) = TableConfig(
+        gameId = "tayu",
+        seats = (0 until options.playerCount).map {
+            PlayerSlot(seat = it, name = "P$it", kind = PlayerKind.AI, team = it % 2)
+        },
+        optionsJson = json.encodeToString(options),
+        seed = seed,
+    )
+
+    /** Seeds that between them give some seat every style at this difficulty. */
+    private fun seedsCoveringStyles(difficulty: AiDifficulty, seats: Int): List<Long> {
+        // The standard opponent is balanced by definition, so there is no style to cover.
+        if (difficulty == AiDifficulty.MEDIUM) return listOf(0L, 1L, 2L)
+        val missing = AiStyle.entries.toMutableSet()
+        val seeds = mutableListOf<Long>()
+        var seed = 0L
+        while (missing.isNotEmpty() && seed < 500) {
+            val styles = (0 until seats).map { AiProfiles(difficulty, seed).of(it).style }
+            if (styles.any { it in missing }) {
+                seeds += seed
+                missing.removeAll(styles.toSet())
+            }
+            seed++
+        }
+        assertTrue("styles never covered: $missing", missing.isEmpty())
+        return seeds
+    }
+
+    private fun play(ai: TayuAi, seed: Long): List<TayuMove> {
+        var state = TayuRules.initialState(config(seed))
+        val moves = mutableListOf<TayuMove>()
+        var guard = 0
+        while (!TayuRules.isFinished(state) && guard++ < 500) {
+            val seat = TayuRules.currentSeat(state) ?: break
+            val legal = TayuRules.legalMoves(state, seat)
+            if (legal.isEmpty()) break
+            val move = ai.chooseMove(state, seat, legal)
+            assertTrue("illegal move $move", legal.contains(move))
+            moves += move
+            state = TayuRules.applyMove(state, seat, move)
+        }
+        assertTrue("game ran away", guard < 500)
+        return moves
+    }
+
+    @Test
+    fun `every level and style plays a whole game legally`() {
+        listOf(AiDifficulty.EASY, AiDifficulty.MEDIUM, AiDifficulty.HARD).forEach { difficulty ->
+            seedsCoveringStyles(difficulty, options.playerCount).forEach { seed ->
+                play(TayuAi(AiProfiles(difficulty, seed)), 500L + seed)
+            }
+        }
+    }
+
+    @Test
+    fun `the gentle table setting is respected at every level`() {
+        listOf(AiDifficulty.EASY, AiDifficulty.HARD).forEach { difficulty ->
+            play(TayuAi(AiProfiles(difficulty, 2L), TayuLevel.GENTLE), 9L)
+        }
+    }
+
+    @Test
+    fun `the default profile plays as the standard opponent`() {
+        val standard = play(TayuAi(), 31L)
+        val medium = play(TayuAi(AiProfiles(AiDifficulty.MEDIUM, 8L)), 31L)
+        assertEquals(standard, medium)
+    }
+}

app/src/test/java/org/prolibertate/games/game/wizard/WizardAiProfilesTest.kt

@@ -0,0 +1,71 @@
+package org.prolibertate.games.game.wizard
+
+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.engine.AiDifficulty
+import org.prolibertate.games.game.engine.AiProfiles
+import org.prolibertate.games.game.engine.PlayerKind
+import org.prolibertate.games.game.engine.PlayerSlot
+import org.prolibertate.games.game.engine.TableConfig
+
+class WizardAiProfilesTest {
+
+    private val json = Json { encodeDefaults = true }
+
+    private fun config(seed: Long, options: WizardOptions) = TableConfig(
+        gameId = "wizard",
+        seats = (0 until options.playerCount).map {
+            PlayerSlot(seat = it, name = "P$it", kind = PlayerKind.AI, team = it)
+        },
+        optionsJson = json.encodeToString(options),
+        seed = seed,
+    )
+
+    /** Plays a whole game with every seat on [ai], returning every move chosen. */
+    private fun playGame(ai: WizardAi, seed: Long, options: WizardOptions): List<WizardMove> {
+        val moves = mutableListOf<WizardMove>()
+        var state = WizardRules.initialState(config(seed, options))
+        var guard = 0
+        while (!WizardRules.isFinished(state) && guard++ < 5000) {
+            val seat = WizardRules.currentSeat(state)
+            if (seat == null) {
+                state = WizardRules.nextRound(state)
+                continue
+            }
+            val legal = WizardRules.legalMoves(state, seat)
+            val move = ai.chooseMove(state, seat, legal)
+            assertTrue("illegal move $move in ${state.phase}", legal.contains(move))
+            moves += move
+            state = WizardRules.applyMove(state, seat, move)
+        }
+        assertTrue("game with seed $seed did not finish", WizardRules.isFinished(state))
+        return moves
+    }
+
+    @Test
+    fun `every difficulty and style plays whole games legally`() {
+        for (difficulty in AiDifficulty.entries) {
+            for (seed in 1L..6L) {
+                val options = WizardOptions(
+                    playerCount = 3 + (seed % 4).toInt(),
+                    rounds = 6,
+                    screwTheDealer = seed % 2L == 0L,
+                )
+                playGame(WizardAi(AiProfiles(difficulty, seed)), seed, options)
+            }
+        }
+    }
+
+    @Test
+    fun `the default profile plays as a medium balanced seat`() {
+        val options = WizardOptions(playerCount = 4, rounds = 6)
+        for (seed in 1L..3L) {
+            val standard = playGame(WizardAi(), seed, options)
+            val explicit = playGame(WizardAi(AiProfiles(AiDifficulty.MEDIUM, 99L)), seed, options)
+            assertEquals(standard, explicit)
+        }
+    }
+}

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

@@ -0,0 +1,95 @@
+package org.prolibertate.games.game.yahtzee
+
+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.engine.AiDifficulty
+import org.prolibertate.games.game.engine.AiProfiles
+import org.prolibertate.games.game.engine.AiStyle
+import org.prolibertate.games.game.engine.PlayerKind
+import org.prolibertate.games.game.engine.PlayerSlot
+import org.prolibertate.games.game.engine.TableConfig
+
+class YahtzeeAiLevelsTest {
+
+    private val json = Json { encodeDefaults = true }
+
+    private fun config(options: YahtzeeOptions, seed: Long) = TableConfig(
+        gameId = "yahtzee",
+        seats = (0 until options.playerCount).map {
+            PlayerSlot(seat = it, name = "P$it", kind = PlayerKind.AI, team = it)
+        },
+        optionsJson = json.encodeToString(options),
+        seed = seed,
+    )
+
+    /** Seeds that between them give some seat every style at this difficulty. */
+    private fun seedsCoveringStyles(difficulty: AiDifficulty, seats: Int): List<Long> {
+        // The standard opponent is balanced by definition, so there is no style to cover.
+        if (difficulty == AiDifficulty.MEDIUM) return listOf(0L, 1L, 2L)
+        val missing = AiStyle.entries.toMutableSet()
+        val seeds = mutableListOf<Long>()
+        var seed = 0L
+        while (missing.isNotEmpty() && seed < 500) {
+            val styles = (0 until seats).map { AiProfiles(difficulty, seed).of(it).style }
+            if (styles.any { it in missing }) {
+                seeds += seed
+                missing.removeAll(styles.toSet())
+            }
+            seed++
+        }
+        assertTrue("styles never covered: $missing", missing.isEmpty())
+        return seeds
+    }
+
+    /** Plays a card out, returning the final state. */
+    private fun play(ai: YahtzeeAi, options: YahtzeeOptions, seed: Long): YahtzeeState {
+        var state = YahtzeeRules.initialState(config(options, seed))
+        var guard = 0
+        while (!YahtzeeRules.isFinished(state) && guard++ < 1000) {
+            val legal = YahtzeeRules.legalMoves(state, state.turn)
+            val move = ai.chooseMove(state, state.turn, legal)
+            assertTrue("illegal move $move", legal.contains(move))
+            state = YahtzeeRules.applyMove(state, state.turn, move)
+        }
+        assertTrue("game ran away", guard < 1000)
+        assertTrue(state.cards.all { it.isComplete })
+        return state
+    }
+
+    @Test
+    fun `every level and style fills a card legally`() {
+        val options = YahtzeeOptions(playerCount = 2)
+        listOf(AiDifficulty.EASY, AiDifficulty.MEDIUM, AiDifficulty.HARD).forEach { difficulty ->
+            seedsCoveringStyles(difficulty, options.playerCount).forEach { seed ->
+                play(YahtzeeAi(AiProfiles(difficulty, seed)), options, 40L + seed)
+            }
+        }
+    }
+
+    @Test
+    fun `the default profile plays as the standard opponent`() {
+        val options = YahtzeeOptions(playerCount = 2)
+        repeat(3) { i ->
+            val standard = play(YahtzeeAi(), options, 70L + i)
+            val medium = play(YahtzeeAi(AiProfiles(AiDifficulty.MEDIUM, 3L + i)), options, 70L + i)
+            assertEquals(standard.cards, medium.cards)
+        }
+    }
+
+    @Test
+    fun `hard scores clearly more than easy over a run of solo games`() {
+        val options = YahtzeeOptions(playerCount = 1)
+        fun average(difficulty: AiDifficulty): Double =
+            (1..12).map { i ->
+                play(YahtzeeAi(AiProfiles(difficulty, i.toLong())), options, 900L + i).totalFor(0)
+            }.average()
+
+        val easy = average(AiDifficulty.EASY)
+        val hard = average(AiDifficulty.HARD)
+        println("yahtzee solo average: easy $easy, hard $hard")
+        assertTrue("hard $hard did not beat easy $easy", hard > easy + 20)
+    }
+}

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

@@ -272,7 +272,7 @@ class YahtzeeRulesTest {
         var guard = 200
         while (!YahtzeeRules.isFinished(state) && guard-- > 0) {
             val legal = YahtzeeRules.legalMoves(state, state.turn)
-            state = YahtzeeRules.applyMove(state, state.turn, YahtzeeAi.chooseMove(state, state.turn, legal))
+            state = YahtzeeRules.applyMove(state, state.turn, YahtzeeAi().chooseMove(state, state.turn, legal))
         }
         assertTrue("the game should end on its own", guard > 0)
         assertTrue(YahtzeeRules.isFinished(state))
@@ -288,7 +288,7 @@ class YahtzeeRulesTest {
         var guard = 400
         while (!YahtzeeRules.isFinished(state) && guard-- > 0) {
             val legal = YahtzeeRules.legalMoves(state, state.turn)
-            state = YahtzeeRules.applyMove(state, state.turn, YahtzeeAi.chooseMove(state, state.turn, legal))
+            state = YahtzeeRules.applyMove(state, state.turn, YahtzeeAi().chooseMove(state, state.turn, legal))
         }
         assertTrue(guard > 0)
         assertTrue(state.cards.all { it.isComplete })

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

@@ -155,9 +155,9 @@ class SaveRoundTripAllGamesTest {
     @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 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 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()))
@@ -171,7 +171,7 @@ class SaveRoundTripAllGamesTest {
         GameCatalog.CATAN,
         CatanRules,
         CatanAi(),
-        opts(CatanOptions(3, 13, org.prolibertate.games.game.catan.CatanRuleSet.CITIES_AND_KNIGHTS)),
+        opts(CatanOptions(3, 13, setOf(org.prolibertate.games.game.catan.CatanExpansion.CITIES_AND_KNIGHTS))),
         steps = 600,
     )
 }

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

@@ -21,7 +21,7 @@ import org.prolibertate.games.game.catan.CatanBoard
 import org.prolibertate.games.game.catan.CatanMove
 import org.prolibertate.games.game.catan.CatanOptions
 import org.prolibertate.games.game.catan.CatanPhase
-import org.prolibertate.games.game.catan.CatanRuleSet
+import org.prolibertate.games.game.catan.CatanExpansion
 import org.prolibertate.games.game.catan.CatanRules
 import org.prolibertate.games.game.catan.CatanState
 import org.prolibertate.games.game.catan.ChaseRobber
@@ -69,7 +69,7 @@ class CatanCkInteractionTest {
         gameId = GameCatalog.CATAN,
         seats = (0 until players).map { PlayerSlot(seat = it, name = "P$it", kind = PlayerKind.AI, team = it) },
         optionsJson = json.encodeToString(
-            CatanOptions(players, pointsToWin = 13, ruleSet = CatanRuleSet.CITIES_AND_KNIGHTS),
+            CatanOptions(players, pointsToWin = 13, expansions = setOf(CatanExpansion.CITIES_AND_KNIGHTS)),
         ),
         seed = seed,
     )

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

@@ -8,7 +8,7 @@ import org.junit.Test
 import org.prolibertate.games.game.GameCatalog
 import org.prolibertate.games.game.catan.CatanAi
 import org.prolibertate.games.game.catan.CatanOptions
-import org.prolibertate.games.game.catan.CatanRuleSet
+import org.prolibertate.games.game.catan.CatanExpansion
 import org.prolibertate.games.game.catan.CatanRules
 import org.prolibertate.games.game.catan.ProgressType
 import org.prolibertate.games.game.engine.PlayerKind
@@ -16,7 +16,7 @@ import org.prolibertate.games.game.engine.PlayerSlot
 import org.prolibertate.games.game.engine.TableConfig
 import org.prolibertate.games.ui.catanDefaultPoints
 import org.prolibertate.games.ui.catanPointsChoices
-import org.prolibertate.games.ui.catanSwitchRules
+import org.prolibertate.games.ui.catanToggleExpansion
 
 class CatanCkTextTest {
 
@@ -28,7 +28,7 @@ class CatanCkTextTest {
             gameId = GameCatalog.CATAN,
             seats = (0 until 3).map { PlayerSlot(seat = it, name = "P$it", kind = PlayerKind.AI, team = it) },
             optionsJson = json.encodeToString(
-                CatanOptions(3, 13, CatanRuleSet.CITIES_AND_KNIGHTS),
+                CatanOptions(3, 13, setOf(CatanExpansion.CITIES_AND_KNIGHTS)),
             ),
             seed = 31L,
         )
@@ -56,20 +56,27 @@ class CatanCkTextTest {
 
     @Test
     fun `the setup screen offers each rule set its own targets and switches sensibly`() {
-        assertEquals(listOf(5, 8, 10, 12), catanPointsChoices(CatanRuleSet.BASE))
-        assertEquals(listOf(8, 10, 13, 15), catanPointsChoices(CatanRuleSet.CITIES_AND_KNIGHTS))
-        assertEquals(10, catanDefaultPoints(CatanRuleSet.BASE))
-        assertEquals(13, catanDefaultPoints(CatanRuleSet.CITIES_AND_KNIGHTS))
+        assertEquals(listOf(5, 8, 10, 12), catanPointsChoices(emptySet()))
+        assertEquals(listOf(8, 10, 13, 15), catanPointsChoices(setOf(CatanExpansion.CITIES_AND_KNIGHTS)))
+        assertEquals(10, catanDefaultPoints(emptySet()))
+        assertEquals(13, catanDefaultPoints(setOf(CatanExpansion.CITIES_AND_KNIGHTS)))
 
         val base = CatanOptions()
-        val ck = catanSwitchRules(base, CatanRuleSet.CITIES_AND_KNIGHTS)
-        assertEquals(CatanRuleSet.CITIES_AND_KNIGHTS, ck.ruleSet)
+        val ck = catanToggleExpansion(base, CatanExpansion.CITIES_AND_KNIGHTS, true)
+        assertEquals(setOf(CatanExpansion.CITIES_AND_KNIGHTS), ck.expansions)
         assertEquals("the published target for the new rules", 13, ck.pointsToWin)
-        assertEquals(10, catanSwitchRules(ck, CatanRuleSet.BASE).pointsToWin)
+        assertEquals(10, catanToggleExpansion(ck, CatanExpansion.CITIES_AND_KNIGHTS, false).pointsToWin)
 
         // A short game picked on purpose is kept when both menus have it.
-        val short = catanSwitchRules(base.copy(pointsToWin = 8), CatanRuleSet.CITIES_AND_KNIGHTS)
+        val short = catanToggleExpansion(base.copy(pointsToWin = 8), CatanExpansion.CITIES_AND_KNIGHTS, true)
         assertEquals(8, short.pointsToWin)
         assertEquals(3, ck.playerCount)
+
+        // Expansions stack: both on has its own menu, and turning one off leaves the other.
+        val both = catanToggleExpansion(ck, CatanExpansion.SEAFARERS, true)
+        assertEquals(setOf(CatanExpansion.CITIES_AND_KNIGHTS, CatanExpansion.SEAFARERS), both.expansions)
+        assertEquals(listOf(10, 12, 14, 16), catanPointsChoices(both.expansions))
+        assertEquals(14, both.pointsToWin)
+        assertEquals(setOf(CatanExpansion.SEAFARERS), catanToggleExpansion(both, CatanExpansion.CITIES_AND_KNIGHTS, false).expansions)
     }
 }

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

@@ -28,7 +28,8 @@ internal object CatanFixtures {
 
     /** A fresh table, on the first setup placement. */
     fun start(players: Int = 3, seed: Long = 7L): CatanState =
-        CatanRules.initialState(config(players, seed))
+        // These tests are about the screen, not who starts: pin seat 0 first.
+        CatanRules.initialState(config(players, seed)).let { it.copy(firstSeat = 0, turn = 0) }
 
     /** A mid-game state on [turn]'s turn, then adjusted by [adjust]. */
     fun playing(

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

@@ -12,7 +12,7 @@ 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.CatanExpansion
 import org.prolibertate.games.game.catan.CatanRules
 import org.prolibertate.games.game.catan.CatanState
 import org.prolibertate.games.game.catan.MovePirate
@@ -29,7 +29,7 @@ import org.prolibertate.games.game.engine.TableConfig
 class CatanSeafarersInteractionTest {
 
     private fun fresh(): CatanState {
-        val options = CatanOptions(playerCount = 3, pointsToWin = 12, ruleSet = CatanRuleSet.SEAFARERS)
+        val options = CatanOptions(playerCount = 3, pointsToWin = 12, expansions = setOf(CatanExpansion.SEAFARERS))
         return CatanRules.initialState(
             TableConfig(
                 gameId = GameCatalog.CATAN,

docs/RE-catan-universe.md

@@ -66,7 +66,13 @@ A full-width panel that slides up over the bottom of the screen (`Animator`, col
 * **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.
+  **not** part of the physical Seafarers rules. Names and texts only (rule values are compiled code):
+  `TreasureRule` with chest outcomes (bricks, wool, grain; a resource; a development card; two roads),
+  `SeafarerOasis` (no rule class of its own, base-game rules), and `GreatCanalRule` with `BuildCanal`,
+  `CanalVictoryPoints`, "The canal was completely dug. Now grain can be grown." and a target of 21 / 18 points.
+  The base-game scenario `baseharbormaster`: "2 victory points. This card goes to the first player to acquire at
+  least 3 harbors. If another player acquires more, he will immediately receive this card."
+  Implemented as inferred rules; see `docs/RULES-catan-seafarers.md`.
 * **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

docs/RULES-catan-ck.md

@@ -220,3 +220,10 @@ game in `CatanCkSelfPlayTest` ends in a win at thirteen points.
 - No animation for the event die, the barbarian landing or a knight's move.
 - The Commercial Harbor offers a single resource type (see above).
 - The AI is not a strong opponent and makes no claim to be.
+
+## On a Seafarers map
+
+Cities & Knights can be played on a Seafarers map; the rules for how the two meet are in
+[RULES-catan-seafarers.md](RULES-catan-seafarers.md#with-cities--knights). The code reads the board from
+`state.topo` throughout, so nothing here assumes the 19-hex island.
+

docs/RULES-catan-seafarers.md

@@ -1,20 +1,47 @@
 # Katan: Seafarers
 
-The Seafarers rule set is chosen at setup next to *Base game* and *Cities & Knights*. It is the base
+Seafarers is an expansion switched on at setup (`CatanOptions.expansions`; the old single `ruleSet` in saves is still read) and its map is chosen beside it (`CatanOptions.scenario`). 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.
+(null in the other rule sets). It can be combined with Cities & Knights; see *With Cities & Knights* below.
 
 Where the published rules leave room, or where this game differs, it says so below.
 
-## The map
+## The maps
 
-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
+Each map is a fixed arrangement of land and sea; the **resources on the plain 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).
+Pick the map at setup; each scenario names where the starting settlements may go (`SeaStart`).
+
+* **Heading for New Shores** (default). A large home island (21 hexes, one desert) and three small islands (3, 3
+  and 2 hexes) across the water, with gold fields on two of the small ones. Start on the home island.
+* **Four Islands.** Four equal islands (six hexes each) and two one-hex gold islets between them. Each player
+  may start on **any** of the four main islands, so a table can spread out or crowd one; the islets are the
+  prize for the first ship to arrive.
+* **Through the Desert.** One 25-hex island cut across by a broad desert (seven hexes that pay nothing and
+  hold the robber), with three islets and gold to sail to. Everyone starts on the island. The desert is
+  land, so a road can cross it, but nothing beside it pays, which is what makes the far side a race.
+
+* **The Fog Islands.** A 13-hex home island (one desert), a two-hex islet and a 14-hex bank of fog.
+  See *Fog* below.
+
+* **Cloth for Catan.** A 17-hex main island, an eastern isle, two islets, and four **villages** on the coast.
+  See *Cloth* below.
+* **The Forgotten Tribe.** A 17-hex home island and three isles carrying four tribe chips. See *The Forgotten
+  Tribe* below.
+
+* **Pirate Islands.** An 18-hex home island and two isles (five and four hexes) each held by a pirate
+  fortress. See *Pirate Islands* below.
+* **Wonders of Catan.** A 13-hex island with a desert, a 12-hex island, and gold islets. See *Wonders* below.
+
+* **The Treasure Islands** *(Catan Universe extra)*. A 15-hex home island and four fog isles, eight hexes of fog in
+  all. See *Catan Universe extras* below.
+* **The Oases** *(Catan Universe extra)*. One 37-hex island that is mostly desert, with three oases hidden in it.
+* **The Great Canal** *(Catan Universe extra)*. A 25-hex island split by a row of five canal tiles, and gold islets.
+
+A *new island* for the bonus is any island that is not a starting island for that map.
 
 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
@@ -56,16 +83,124 @@ through an opponent's town and changes between road and ship only at a town of y
 
 Everything else (development cards, trading, harbours, Largest Army, the discard on a seven) is the base game.
 
+## Fog
+
+Fog hexes (`Terrain.FOG`) are land that is face down. Under them is a shuffled pile of tiles
+(`SeaState.fogDeck`): resources, with one gold field in every five, each with its number token. The
+pile is hidden from every seat but the host's, like the development deck.
+
+* **Finding.** When a road or ship is built (or a ship sails) and an end of it touches a fog hex, the hex is
+  turned over, taking the next tile and its number. Several hexes can be found by one piece.
+* **The find pays.** The finder takes one card of what lies there, supply permitting; a gold field lets the
+  finder choose any resource (the gold choice, resuming Road Building if that is what was under way).
+* **Until then** nothing produces there, nobody may start beside it, and the robber cannot go on it.
+* **Differences from the published scenario.** The fog here is always land: the physical tiles can turn out to
+  be sea, but the board's land and sea are fixed in the geometry, so a found hex never turns to water. Fog is
+  also on one bank rather than between several islands, and the number tokens are dealt with the tiles, so two
+  red numbers can end up side by side once found.
+
+## Cloth
+
+The published scenario puts cloth villages between the islands and pays cloth when a village's number is rolled.
+This implementation is the author's reading of that, not a transcription of the printed rules:
+
+* A **village** is a land hex with a number token and a stock of cloth (6). It produces no cards and nothing may
+  be built on it, but its corners can hold settlements like any other hex's.
+* When its number rolls, the village pays **one cloth token** to each settlement or city beside it (a city is
+  worth no more than a settlement here), until the stock is gone. If the stock is short, the seats nearest the
+  roller, in turn order, take what is left. The robber on a village stops it; the pirate does not.
+* **Two cloth are a victory point** (an odd token is worth nothing alone). Tokens are scored, not spent, and not
+  tradeable.
+* Works with Cities & Knights: the village pays after the dice, before the aqueduct and gold.
+
+## The Forgotten Tribe
+
+Also the author's reading. A chip lies face up on four hexes of the small isles (the hexes are marked on the
+board). The chips are dealt at the start of the game, one of each kind in turn:
+
+* **The first settlement** built on a crossing beside a chip hex takes that chip; it is gone for everyone else.
+  (The setup settlements are never beside one, since the home island is the only start.)
+* A **point** chip is one victory point. A **harbour** chip lets that seat trade 3:1 at the bank, wherever it is.
+  A **gold** chip pays two resources of the settler's choice, taken at once like gold.
+* The chips come on top of the island bonus for being first to a new island.
+
+## Pirate Islands
+
+The author's reading of the scenario; the printed one uses knights and a roaming pirate fleet, which this does not.
+
+* A **fortress** is a land hex with no number and a strength of 3. Nobody may build a settlement on any crossing of
+  an island that still has a standing fortress. Roads and ships may go there.
+* A seat with a **ship beside** a fortress may **raid** it in its turn for 1 ore, 1 wool and 1 grain, as many times as
+  it can pay. Each raid takes one point of strength.
+* The raid that takes the last point **takes the fortress**: the hex becomes desert (no number, robber may sit there),
+  the island is open to settle for everyone, and the taker gets **2 victory points**. The robber never sits on a
+  standing fortress.
+* The island still counts as a new island for the first-landing bonus.
+
+## Wonders
+
+Also the author's reading. Every seat may build one wonder in four stages, once it has a **city** anywhere on the
+board. Each stage is one move costing cards (stage 1: 2 brick, 1 lumber, 1 grain; 2: 1 brick, 2 ore, 1 wool; 3: 3 ore,
+1 grain, 1 lumber; 4: 3 ore, 2 grain, 1 brick). Each stage built is **one victory point**, and the seat that
+builds the fourth stage **wins at once**, whatever the point target. Wonders are not shared: each seat has its own.
+
+## Catan Universe extras (inferred)
+
+These three exist in the Catan Universe app but not in the physical set. Only their names, menu texts and log
+lines could be read (`docs/RE-catan-universe.md`); the rule values are compiled code that was not recovered. **Every
+rule below is inferred from those names and texts**, not copied.
+
+* **Treasure Islands.** The app's text: "Treasures await the Catanians on neighboring, fog-covered islands.
+  Discoveries are rewarded!" Its chest rewards (log texts and action names) are bricks, wool and grain; a resource of
+  choice; a development card; two roads. Here: up to five chests are dealt face down to random fog hexes at the
+  start. A seat that uncovers the hex (the fog rules) opens the chest at once and takes: *a brick, a wool and a grain*;
+  *one resource of its choice* (a gold pick); *a development card* (a resource of choice if the deck is empty or it is
+  Cities & Knights, which has no deck); or *two lumber and two brick* standing in for two free roads (the free-roads
+  phase would have to nest inside a ship move). The app's Cities & Knights version gives a progress card; that is
+  not modelled. The app's fixed treasure bonus (`SEAFARER_TREASURE_BONUS`) is not modelled either.
+* **The Oases.** The app's text: an enormous desert with rumoured oases and treasures, base-game rules. Here: the
+  oases are fog hexes inside the desert, uncovered by a road reaching them, and hold the same chests as above.
+  There is no ship rule on the map itself.
+* **The Great Canal.** The app's text, for Cities & Knights plus Seafarers: build a canal; first to 21 (3 players) or
+  18 (4 players) wins; the canal's parts earn victory points; when a tile is dug out, grain grows there. Its knights dig
+  in the app; here digging is cheaper to implement and play without Cities & Knights: a canal tile is a desert hex with
+  its number token hidden. A seat with a settlement or city on a corner of the tile digs one **unit** for 1 brick and
+  1 ore; **three units** finish the tile, which becomes **fields** with the hidden number. Every **two units** a seat
+  has dug are a **victory point**. The app's gold river, harbour changes and target scores are not modelled.
+
+## With Cities & Knights
+
+Switching both expansions on plays [Cities & Knights](RULES-catan-ck.md) on any Seafarers map
+(`CatanState.ck` and `CatanState.sea` both set; the target menu is 10, 12, 14 or 16, default 14).
+Where the two meet, this game decides as follows:
+
+* **Ships** cost 1 lumber and 1 wool as before and are built and sailed in a turn like a road, including
+  with the Road Building progress card (roads and ships, as in Seafarers).
+* **Knights** stand on land crossings at the end of one of your roads *or ships*, and walk along that same
+  network. A crossing that touches only sea is never a knight post.
+* **The pirate** sleeps with the robber: only after the first barbarian attack does a seven let the player
+  move the robber (to land) *or* the pirate (to sea). The pirate robs one good, resource or commodity, from a
+  seat with a ship beside it. The bishop moves the robber only.
+* **Gold** pays after the roll and before the aqueduct and any other chore: a settlement beside it chooses one
+  resource, a city two. (A city on gold takes two resources, not a resource and a commodity.)
+* **Scoring.** First-landing bonus points are added to a seat's points like any other; the barbarians count
+  cities wherever they stand, island or not.
+* **Merchant** goes only on a land hex; **Fog** works as in Seafarers (a find pays a resource card).
+
 ## 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.
+the Explorers & Pirates combination,
+the printed rules of the wonders and pirate-islands scenarios (the versions here are simplified) and trade ships.
+Drought and the app's other scenarios (Six Islands, Oceania, Great Catan, Enchanted Land, the Inka and Big Game sets)
+are not built.
+A map-only scenario is a new text map and a new `SeaScenario` 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
+bonus is in play. A spot beside a village that still has cloth, or beside a tribe chip nobody has taken, is
+worth more (`CatanAi.scenarioLure`), a ship that heads for a standing fortress is worth building, and it raids and builds
+wonder stages whenever it can pay (`CatanAi.FORT_LURE`). 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-catan.md

@@ -23,6 +23,26 @@ A table plays one of two rule sets, chosen on the setup screen
   building, robber and trade rules and changes or replaces the rest; its state lives
   behind `CatanState.ck`, which is `null` in the base game.
 
+## Base-island scenarios
+
+Without Seafarers the setup screen offers an **Island** choice (`CatanOptions.baseScenario`; it works with Cities &
+Knights too). Both extras are the author's reading, not transcriptions of the printed scenarios:
+
+- **Random map** (default) — the usual shuffled island.
+- **First Island** — the same island every game: one fixed shuffle (`CatanBoard.FIRST_ISLAND_SEED`) of the standard
+  tiles, numbers and harbours, so a first game or a rematch has no surprise set-up. It is not the printed beginner
+  layout. The development deck and the seating still follow the table's own seed.
+- **The Harbormaster** — the Catan Universe menu text is "Because trade becomes more and more important, harbours
+  have an ever increasing significance." Its card: 2 victory points to the first player with at least three harbour
+  points; another player with more takes it at once. What a harbour point is was not in the app's texts, so it is
+  inferred: a settlement on a harbour counts **1**, a city **2**, for each harbour it touches. The title is checked after
+  every settlement, city and set-up placement; **equal points do not take it**, only strictly more (like Longest
+  Road); it is **+2 victory points** to the holder (`CatanState.harbormaster`). The AI values a harbour spot a
+  little more here (`CatanAi.HARBOR_LURE`).
+
+Seafarers games choose a map instead (see [RULES-catan-seafarers.md](RULES-catan-seafarers.md)); the Harbormaster does not apply there.
+The app's other base scenario, Ore for Wool, is not built: its rules are not in the texts that could be read.
+
 ## Table
 
 - **Rules — *toggle*.** Base game or Cities & Knights (`CatanOptions.ruleSet`).