Merge pull request #20: FreeCell, Spider and Pyramid

Three more patiences, all playable, and the Klondike table laid out the way
a real one is.

Verified by ci.yml runs 100 and 101, green across build, tests and lint.

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

@@ -40,6 +40,9 @@ object GameCatalog {
 
     const val YAHTZEE = "yahtzee"
     const val KLONDIKE = "klondike"
+    const val FREECELL = "freecell"
+    const val SPIDER = "spider"
+    const val PYRAMID = "pyramid"
     const val SEQUENCE = "sequence"
     const val MASTERMIND = "mastermind"
     const val BACKGAMMON = "backgammon"
@@ -144,6 +147,39 @@ object GameCatalog {
                 "and a pack that decides most of it before you start.",
             available = true,
         ),
+        GameDescriptor(
+            id = FREECELL,
+            title = "FreeCell",
+            category = GameCategory.CARD,
+            minPlayers = 1,
+            maxPlayers = 1,
+            teamBased = false,
+            blurb = "Every card face up from the start, and four cells to park what is " +
+                "in the way. Nearly every deal can be won by someone good enough.",
+            available = true,
+        ),
+        GameDescriptor(
+            id = SPIDER,
+            title = "Spider",
+            category = GameCategory.CARD,
+            minPlayers = 1,
+            maxPlayers = 1,
+            teamBased = false,
+            blurb = "Two packs, ten columns, eight runs to build from king to ace. " +
+                "One suit is a pastime; four is a fight.",
+            available = true,
+        ),
+        GameDescriptor(
+            id = PYRAMID,
+            title = "Pyramid",
+            category = GameCategory.CARD,
+            minPlayers = 1,
+            maxPlayers = 1,
+            teamBased = false,
+            blurb = "Take cards away in pairs that make thirteen, kings alone. " +
+                "Nothing is built and nothing goes home — the pyramid just has to go.",
+            available = true,
+        ),
         GameDescriptor(
             id = SEQUENCE,
             title = "Sequence",

app/src/main/java/org/prolibertate/games/game/freecell/FreeCellModel.kt

@@ -0,0 +1,81 @@
+package org.prolibertate.games.game.freecell
+
+import kotlinx.serialization.SerialName
+import kotlinx.serialization.Serializable
+import org.prolibertate.games.game.cards.Card
+
+const val COLUMNS: Int = 8
+const val FOUNDATIONS: Int = 4
+
+@Serializable
+enum class CellKind { CELL, TABLEAU, FOUNDATION }
+
+@Serializable
+data class Place(val kind: CellKind, val index: Int) {
+    companion object {
+        fun cell(index: Int) = Place(CellKind.CELL, index)
+        fun column(index: Int) = Place(CellKind.TABLEAU, index)
+        fun foundation(index: Int) = Place(CellKind.FOUNDATION, index)
+    }
+}
+
+@Serializable
+data class FreeCellOptions(
+    /**
+     * Four cells is the game as everyone knows it. Fewer is the same game made
+     * hard, since the cells are the only place a card can wait.
+     */
+    val freeCells: Int = 4,
+    /**
+     * Move a run in one gesture rather than a card at a time. The rules do not
+     * actually allow it — a run is moved by shuffling cards through the cells —
+     * but every computer version does it for you, because doing it by hand is
+     * bookkeeping rather than a decision.
+     */
+    val allowSupermoves: Boolean = true,
+) {
+    init {
+        require(freeCells in 1..6) { "One to six cells" }
+    }
+}
+
+@Serializable
+data class FreeCellState(
+    val options: FreeCellOptions,
+    val seed: Long,
+    /** Null where a cell is empty. */
+    val cells: List<Card?>,
+    val foundations: List<List<Card>>,
+    /** Every card is face up in FreeCell; there is nothing buried to turn. */
+    val tableau: List<List<Card>>,
+    val moves: Int,
+    val log: List<String>,
+) {
+    val freeCellCount: Int get() = cells.count { it == null }
+    val emptyColumns: Int get() = tableau.count { it.isEmpty() }
+    val isWon: Boolean get() = foundations.all { it.size == 13 }
+}
+
+@Serializable
+sealed interface FreeCellMove
+
+@Serializable
+@SerialName("move")
+data class MoveTo(val from: Place, val to: Place, val count: Int = 1) : FreeCellMove
+
+/**
+ * How many cards can travel together.
+ *
+ * A run is really moved one card at a time through the free cells and the empty
+ * columns, so what can be shifted is what those could have held: one per free
+ * cell plus the card itself, doubled for every empty column that could be used
+ * as a staging pile. Moving *into* an empty column cannot also use it, which is
+ * the fiddly part and the reason [intoEmptyColumn] exists.
+ */
+fun maxRunLength(freeCells: Int, emptyColumns: Int, intoEmptyColumn: Boolean): Int {
+    val usable = if (intoEmptyColumn) emptyColumns - 1 else emptyColumns
+    if (usable < 0) return 1
+    var limit = freeCells + 1
+    repeat(usable) { limit *= 2 }
+    return limit
+}

app/src/main/java/org/prolibertate/games/game/freecell/FreeCellRules.kt

@@ -0,0 +1,193 @@
+package org.prolibertate.games.game.freecell
+
+import kotlinx.serialization.encodeToString
+import kotlinx.serialization.json.Json
+import org.prolibertate.games.game.GameCatalog
+import org.prolibertate.games.game.cards.Card
+import org.prolibertate.games.game.cards.Decks
+import org.prolibertate.games.game.cards.shuffledWith
+import org.prolibertate.games.game.engine.GameRules
+import org.prolibertate.games.game.engine.TableConfig
+import org.prolibertate.games.game.solitaire.acceptsOnFoundation
+import org.prolibertate.games.game.solitaire.buildsDownAlternating
+import org.prolibertate.games.game.solitaire.isRun
+import kotlin.random.Random
+
+/**
+ * FreeCell as a pure state machine. See RULES-freecell.md.
+ *
+ * The whole pack is face up from the first move, so unlike Klondike there is
+ * nothing hidden and nothing to be lucky about — very nearly every deal can be
+ * won by someone who plays it well enough.
+ */
+object FreeCellRules : GameRules<FreeCellState, FreeCellMove> {
+
+    override val gameId: String = GameCatalog.FREECELL
+    const val SOLO_SEAT: Int = 0
+
+    private val json = Json {
+        ignoreUnknownKeys = true
+        encodeDefaults = true
+    }
+
+    override fun initialState(config: TableConfig): FreeCellState {
+        val options = json.decodeFromString<FreeCellOptions>(config.optionsJson)
+        require(config.seats.size == 1) { "FreeCell seats one, not ${config.seats.size}" }
+        return deal(options, config.seed)
+    }
+
+    private fun deal(options: FreeCellOptions, seed: Long): FreeCellState {
+        val deck = Decks.standard52().shuffledWith(Random(seed))
+        // Fifty-two into eight leaves four columns of seven and four of six.
+        val columns = mutableListOf<List<Card>>()
+        var at = 0
+        repeat(COLUMNS) { index ->
+            val size = if (index < 4) 7 else 6
+            columns += deck.subList(at, at + size).toList()
+            at += size
+        }
+        return FreeCellState(
+            options = options,
+            seed = seed,
+            cells = List(options.freeCells) { null },
+            foundations = List(FOUNDATIONS) { emptyList() },
+            tableau = columns,
+            moves = 0,
+            log = listOf("Dealt, with ${options.freeCells} cells."),
+        )
+    }
+
+    override fun currentSeat(state: FreeCellState): Int? =
+        if (isFinished(state)) null else SOLO_SEAT
+
+    /** The longest run sitting on the end of a column, by the build rule. */
+    fun movableTail(column: List<Card>): List<Card> {
+        if (column.isEmpty()) return emptyList()
+        var take = 1
+        while (take < column.size) {
+            val candidate = column.takeLast(take + 1)
+            if (!isRun(candidate, ::buildsDownAlternating)) break
+            take++
+        }
+        return column.takeLast(take)
+    }
+
+    override fun legalMoves(state: FreeCellState, seat: Int): List<FreeCellMove> {
+        if (seat != SOLO_SEAT || state.isWon) return emptyList()
+        val moves = mutableListOf<FreeCellMove>()
+
+        fun offer(from: Place, cards: List<Card>) {
+            val head = cards.first()
+            if (cards.size == 1) {
+                val foundation = head.suit.ordinal
+                if (acceptsOnFoundation(state.foundations[foundation], head)) {
+                    moves += MoveTo(from, Place.foundation(foundation), 1)
+                }
+                state.cells.indices.forEach { cell ->
+                    if (state.cells[cell] == null && from.kind != CellKind.CELL) {
+                        moves += MoveTo(from, Place.cell(cell), 1)
+                    }
+                }
+            }
+            state.tableau.indices.forEach { column ->
+                if (from.kind == CellKind.TABLEAU && from.index == column) return@forEach
+                val target = state.tableau[column]
+                val fits = target.lastOrNull()?.let { buildsDownAlternating(head, it) } ?: true
+                if (!fits) return@forEach
+                // Moving a whole column into an empty one is a no-op that would
+                // let a game shuffle for ever.
+                if (target.isEmpty() && from.kind == CellKind.TABLEAU &&
+                    cards.size == state.tableau[from.index].size
+                ) {
+                    return@forEach
+                }
+                val allowed = maxRunLength(
+                    freeCells = state.freeCellCount,
+                    emptyColumns = state.emptyColumns,
+                    intoEmptyColumn = target.isEmpty(),
+                ).let { if (state.options.allowSupermoves) it else 1 }
+                if (cards.size <= allowed) moves += MoveTo(from, Place.column(column), cards.size)
+            }
+        }
+
+        state.cells.forEachIndexed { index, card ->
+            card?.let { offer(Place.cell(index), listOf(it)) }
+        }
+        state.tableau.forEachIndexed { index, column ->
+            val tail = movableTail(column)
+            // Every length of the tail run can travel, not just the whole of it.
+            for (count in 1..tail.size) {
+                offer(Place.column(index), tail.takeLast(count))
+            }
+        }
+        return moves
+    }
+
+    override fun applyMove(state: FreeCellState, seat: Int, move: FreeCellMove): FreeCellState {
+        require(seat == SOLO_SEAT) { "FreeCell has one seat" }
+        require(legalMoves(state, seat).contains(move)) { "$move is not legal here" }
+        move as MoveTo
+        val cards = when (move.from.kind) {
+            CellKind.CELL -> listOfNotNull(state.cells[move.from.index])
+            CellKind.TABLEAU -> state.tableau[move.from.index].takeLast(move.count)
+            CellKind.FOUNDATION -> state.foundations[move.from.index].takeLast(move.count)
+        }
+        var next = when (move.from.kind) {
+            CellKind.CELL -> state.copy(cells = state.cells.replacing(move.from.index, null))
+            CellKind.TABLEAU -> state.copy(
+                tableau = state.tableau.replacing(
+                    move.from.index,
+                    state.tableau[move.from.index].dropLast(move.count),
+                ),
+            )
+
+            CellKind.FOUNDATION -> state.copy(
+                foundations = state.foundations.replacing(
+                    move.from.index,
+                    state.foundations[move.from.index].dropLast(move.count),
+                ),
+            )
+        }
+        next = when (move.to.kind) {
+            CellKind.CELL -> next.copy(cells = next.cells.replacing(move.to.index, cards.single()))
+            CellKind.TABLEAU -> next.copy(
+                tableau = next.tableau.replacing(
+                    move.to.index,
+                    next.tableau[move.to.index] + cards,
+                ),
+            )
+
+            CellKind.FOUNDATION -> next.copy(
+                foundations = next.foundations.replacing(
+                    move.to.index,
+                    next.foundations[move.to.index] + cards,
+                ),
+            )
+        }
+        return next.copy(
+            moves = state.moves + 1,
+            log = if (next.isWon) next.log + "Out, in ${state.moves + 1} moves." else next.log,
+        )
+    }
+
+    private fun <T> List<T>.replacing(index: Int, value: T): List<T> =
+        toMutableList().also { it[index] = value }
+
+    override fun isFinished(state: FreeCellState): Boolean =
+        state.isWon || legalMoves(state, SOLO_SEAT).isEmpty()
+
+    override fun summary(state: FreeCellState): String = when {
+        state.isWon -> "Out in ${state.moves} moves"
+        isFinished(state) -> "Blocked, ${state.foundations.sumOf { it.size }} cards home"
+        else -> "${state.foundations.sumOf { it.size }} of 52 home"
+    }
+
+    override fun viewFor(state: FreeCellState, seat: Int): FreeCellState = state
+
+    override fun encodeState(state: FreeCellState): String = json.encodeToString(state)
+    override fun decodeState(json: String): FreeCellState = this.json.decodeFromString(json)
+    override fun encodeMove(move: FreeCellMove): String = json.encodeToString(move)
+    override fun decodeMove(json: String): FreeCellMove = this.json.decodeFromString(json)
+
+    fun restart(state: FreeCellState): FreeCellState = deal(state.options, state.seed)
+}

app/src/main/java/org/prolibertate/games/game/pyramid/PyramidModel.kt

@@ -0,0 +1,98 @@
+package org.prolibertate.games.game.pyramid
+
+import kotlinx.serialization.SerialName
+import kotlinx.serialization.Serializable
+import org.prolibertate.games.game.cards.Card
+import org.prolibertate.games.game.solitaire.patienceOrder
+
+/** Seven rows of one to seven cards. */
+const val ROWS: Int = 7
+const val PYRAMID_SIZE: Int = ROWS * (ROWS + 1) / 2
+
+/** A pair has to make this, and a king makes it alone. */
+const val TARGET: Int = 13
+
+@Serializable
+enum class PyramidZone { PYRAMID, WASTE }
+
+@Serializable
+data class PyramidSpot(val zone: PyramidZone, val index: Int = 0)
+
+@Serializable
+data class PyramidOptions(
+    /** How many times the waste may be turned back over. */
+    val redeals: Int = 2,
+) {
+    init {
+        require(redeals >= 0) { "redeals cannot be negative" }
+    }
+}
+
+@Serializable
+data class PyramidState(
+    val options: PyramidOptions,
+    val seed: Long,
+    /** Twenty-eight places; null where the card has been taken. */
+    val pyramid: List<Card?>,
+    val stock: List<Card>,
+    val waste: List<Card>,
+    val redealsUsed: Int,
+    val moves: Int,
+    val log: List<String>,
+) {
+    val isWon: Boolean get() = pyramid.all { it == null }
+
+    val canRedeal: Boolean
+        get() = stock.isEmpty() && waste.isNotEmpty() && redealsUsed < options.redeals
+}
+
+@Serializable
+sealed interface PyramidMove
+
+@Serializable
+@SerialName("draw")
+data object DrawCard : PyramidMove
+
+@Serializable
+@SerialName("redeal")
+data object RecycleWaste : PyramidMove
+
+/** A king is worth thirteen on its own, so it needs no partner. */
+@Serializable
+@SerialName("king")
+data class TakeKing(val spot: PyramidSpot) : PyramidMove
+
+@Serializable
+@SerialName("pair")
+data class TakePair(val first: PyramidSpot, val second: PyramidSpot) : PyramidMove
+
+/** Ace one through king thirteen, which is what the pairing is counted in. */
+fun valueOf(card: Card): Int = card.rank.patienceOrder
+
+/** Where a row starts in the flattened pyramid. */
+fun rowStart(row: Int): Int = row * (row + 1) / 2
+
+/** Which row a place is in. */
+fun rowOf(index: Int): Int {
+    var row = 0
+    while (rowStart(row + 1) <= index) row++
+    return row
+}
+
+/**
+ * The two places resting on [index], if any.
+ *
+ * A card is only in play once both of them are gone, which is the whole shape of
+ * the game: the pyramid has to be taken apart from the bottom.
+ */
+fun coveredBy(index: Int): List<Int> {
+    val row = rowOf(index)
+    if (row == ROWS - 1) return emptyList()
+    val offset = index - rowStart(row)
+    val below = rowStart(row + 1) + offset
+    return listOf(below, below + 1)
+}
+
+/** Whether the card at [index] has nothing left sitting on it. */
+fun isExposed(pyramid: List<Card?>, index: Int): Boolean =
+    pyramid[index] != null && coveredBy(index).all { pyramid[it] == null }

app/src/main/java/org/prolibertate/games/game/pyramid/PyramidRules.kt

@@ -0,0 +1,150 @@
+package org.prolibertate.games.game.pyramid
+
+import kotlinx.serialization.encodeToString
+import kotlinx.serialization.json.Json
+import org.prolibertate.games.game.GameCatalog
+import org.prolibertate.games.game.cards.Card
+import org.prolibertate.games.game.cards.Decks
+import org.prolibertate.games.game.cards.shuffledWith
+import org.prolibertate.games.game.engine.GameRules
+import org.prolibertate.games.game.engine.TableConfig
+import kotlin.random.Random
+
+/**
+ * Pyramid as a pure state machine. See RULES-pyramid.md.
+ *
+ * The odd one out among the patiences here: nothing is built and nothing goes
+ * home in order. Cards are taken away in pairs that make thirteen, and the only
+ * structure is which of them are still buried.
+ */
+object PyramidRules : GameRules<PyramidState, PyramidMove> {
+
+    override val gameId: String = GameCatalog.PYRAMID
+    const val SOLO_SEAT: Int = 0
+
+    private val json = Json {
+        ignoreUnknownKeys = true
+        encodeDefaults = true
+    }
+
+    override fun initialState(config: TableConfig): PyramidState {
+        val options = json.decodeFromString<PyramidOptions>(config.optionsJson)
+        require(config.seats.size == 1) { "Pyramid seats one, not ${config.seats.size}" }
+        return deal(options, config.seed)
+    }
+
+    private fun deal(options: PyramidOptions, seed: Long): PyramidState {
+        val deck = Decks.standard52().shuffledWith(Random(seed))
+        return PyramidState(
+            options = options,
+            seed = seed,
+            pyramid = deck.take(PYRAMID_SIZE),
+            stock = deck.drop(PYRAMID_SIZE),
+            waste = emptyList(),
+            redealsUsed = 0,
+            moves = 0,
+            log = listOf("Dealt."),
+        )
+    }
+
+    override fun currentSeat(state: PyramidState): Int? =
+        if (isFinished(state)) null else SOLO_SEAT
+
+    /** Every card that can be reached: the exposed pyramid, and the waste's top. */
+    fun available(state: PyramidState): List<Pair<PyramidSpot, Card>> {
+        val fromPyramid = state.pyramid.indices
+            .filter { isExposed(state.pyramid, it) }
+            .map { PyramidSpot(PyramidZone.PYRAMID, it) to state.pyramid[it]!! }
+        val fromWaste = state.waste.lastOrNull()
+            ?.let { listOf(PyramidSpot(PyramidZone.WASTE) to it) }
+            .orEmpty()
+        return fromPyramid + fromWaste
+    }
+
+    override fun legalMoves(state: PyramidState, seat: Int): List<PyramidMove> {
+        if (seat != SOLO_SEAT || state.isWon) return emptyList()
+        val moves = mutableListOf<PyramidMove>()
+        if (state.stock.isNotEmpty()) moves += DrawCard
+        if (state.canRedeal) moves += RecycleWaste
+
+        val reachable = available(state)
+        reachable.forEach { (spot, card) ->
+            if (valueOf(card) == TARGET) moves += TakeKing(spot)
+        }
+        // Each pair once: the second card is only ever looked for after the
+        // first, so a pair cannot be offered both ways round.
+        for (i in reachable.indices) {
+            for (j in i + 1 until reachable.size) {
+                val (spotA, cardA) = reachable[i]
+                val (spotB, cardB) = reachable[j]
+                if (valueOf(cardA) + valueOf(cardB) == TARGET) {
+                    moves += TakePair(spotA, spotB)
+                }
+            }
+        }
+        return moves
+    }
+
+    override fun applyMove(state: PyramidState, seat: Int, move: PyramidMove): PyramidState {
+        require(seat == SOLO_SEAT) { "Pyramid has one seat" }
+        require(legalMoves(state, seat).contains(move)) { "$move is not legal here" }
+        val next = when (move) {
+            DrawCard -> state.copy(
+                stock = state.stock.dropLast(1),
+                waste = state.waste + state.stock.last(),
+            )
+
+            RecycleWaste -> state.copy(
+                stock = state.waste.reversed(),
+                waste = emptyList(),
+                redealsUsed = state.redealsUsed + 1,
+                log = state.log + "Waste turned back over.",
+            )
+
+            is TakeKing -> remove(state, listOf(move.spot))
+            is TakePair -> remove(state, listOf(move.first, move.second))
+        }
+        return next.copy(
+            moves = state.moves + 1,
+            log = if (next.isWon) next.log + "Pyramid cleared, in ${state.moves + 1} moves." else next.log,
+        )
+    }
+
+    /**
+     * Takes cards off the table.
+     *
+     * The pyramid places are blanked rather than compacted, because a place is
+     * what tells the two cards above it that they are free — an index that
+     * shifted would uncover the wrong cards.
+     */
+    private fun remove(state: PyramidState, spots: List<PyramidSpot>): PyramidState {
+        val pyramid = state.pyramid.toMutableList()
+        var waste = state.waste
+        spots.forEach { spot ->
+            when (spot.zone) {
+                PyramidZone.PYRAMID -> pyramid[spot.index] = null
+                // Only ever the top card, so dropping the last is enough.
+                PyramidZone.WASTE -> waste = waste.dropLast(1)
+            }
+        }
+        return state.copy(pyramid = pyramid.toList(), waste = waste)
+    }
+
+    override fun isFinished(state: PyramidState): Boolean =
+        state.isWon || legalMoves(state, SOLO_SEAT).isEmpty()
+
+    override fun summary(state: PyramidState): String = when {
+        state.isWon -> "Cleared in ${state.moves} moves"
+        isFinished(state) -> "Blocked, ${state.pyramid.count { it != null }} cards left"
+        else -> "${state.pyramid.count { it != null }} of $PYRAMID_SIZE left"
+    }
+
+    override fun viewFor(state: PyramidState, seat: Int): PyramidState = state
+
+    override fun encodeState(state: PyramidState): String = json.encodeToString(state)
+    override fun decodeState(json: String): PyramidState = this.json.decodeFromString(json)
+    override fun encodeMove(move: PyramidMove): String = json.encodeToString(move)
+    override fun decodeMove(json: String): PyramidMove = this.json.decodeFromString(json)
+
+    fun restart(state: PyramidState): PyramidState = deal(state.options, state.seed)
+}

app/src/main/java/org/prolibertate/games/game/solitaire/HintAi.kt

@@ -0,0 +1,24 @@
+package org.prolibertate.games.game.solitaire
+
+import org.prolibertate.games.game.engine.GameAi
+
+/**
+ * Takes the first move on offer.
+ *
+ * Every patience here has one seat and it belongs to the person playing, so
+ * nothing asks this during an ordinary game. [MatchController] needs an AI to
+ * construct, though, and a seat that could be left empty has to be playable by
+ * something.
+ *
+ * It is deliberately not clever. A greedy patience player that looked good would
+ * be worse than this: it would be trusted as a hint, and a hint that walks a run
+ * back and forth is more annoying than no hint at all. Klondike has a real one
+ * because its move ordering is obvious; these three do not, and pretending
+ * otherwise would be the wrong kind of helpful.
+ */
+class FirstLegalAi<S : Any, M : Any> : GameAi<S, M> {
+    override fun chooseMove(state: S, seat: Int, legal: List<M>): M {
+        require(legal.isNotEmpty()) { "No legal move for seat $seat" }
+        return legal.first()
+    }
+}

app/src/main/java/org/prolibertate/games/game/spider/SpiderModel.kt

@@ -0,0 +1,107 @@
+package org.prolibertate.games.game.spider
+
+import kotlinx.serialization.SerialName
+import kotlinx.serialization.Serializable
+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.solitaire.patienceOrder
+
+const val COLUMNS: Int = 10
+
+/** Eight complete runs, king down to ace, is the whole pack cleared. */
+const val RUNS_TO_WIN: Int = 8
+const val RUN_LENGTH: Int = 13
+
+@Serializable
+data class SpiderOptions(
+    /**
+     * How many suits the two packs are made of. One suit is the game people
+     * actually finish; four is the real thing and is brutal. Two sits between
+     * them. The pack is always a hundred and four cards either way — only how
+     * many different suits those cards are drawn from changes.
+     */
+    val suits: Int = 1,
+) {
+    init {
+        require(suits == 1 || suits == 2 || suits == 4) { "Spider is played with one, two or four suits" }
+    }
+}
+
+@Serializable
+data class SpiderPile(
+    val faceDown: List<Card> = emptyList(),
+    val faceUp: List<Card> = emptyList(),
+) {
+    val isEmpty: Boolean get() = faceDown.isEmpty() && faceUp.isEmpty()
+    val top: Card? get() = faceUp.lastOrNull()
+}
+
+@Serializable
+data class SpiderState(
+    val options: SpiderOptions,
+    val seed: Long,
+    val stock: List<Card>,
+    val tableau: List<SpiderPile>,
+    /** Runs sent away complete. Eight of them wins. */
+    val completed: Int,
+    val moves: Int,
+    val log: List<String>,
+) {
+    val isWon: Boolean get() = completed == RUNS_TO_WIN
+
+    /**
+     * A row cannot be dealt onto an empty column — the rule that stops a deal
+     * from being used to dodge a position with nowhere to put anything.
+     */
+    val canDeal: Boolean get() = stock.isNotEmpty() && tableau.none { it.isEmpty }
+}
+
+@Serializable
+sealed interface SpiderMove
+
+/** One card face up onto every column at once. */
+@Serializable
+@SerialName("deal")
+data object DealRow : SpiderMove
+
+@Serializable
+@SerialName("move")
+data class MoveRun(val from: Int, val to: Int, val count: Int) : SpiderMove
+
+/**
+ * Down by one in the same suit.
+ *
+ * Spider lets a card *land* on any suit a rank higher, but only a same-suit run
+ * may travel as a unit — which is the whole difficulty of the four-suit game.
+ */
+fun sameSuitRun(cards: List<Card>): Boolean =
+    cards.isNotEmpty() && cards.zipWithNext().all { (upper, lower) ->
+        lower.suit == upper.suit && lower.rank.patienceOrder == upper.rank.patienceOrder - 1
+    }
+
+/** What a column will take on top: anything one rank higher, of any suit. */
+fun landsOn(card: Card, onto: Card): Boolean =
+    card.rank.patienceOrder == onto.rank.patienceOrder - 1
+
+/** King down to ace in one suit, which is a run ready to go away. */
+fun isCompleteRun(cards: List<Card>): Boolean =
+    cards.size == RUN_LENGTH &&
+        cards.first().rank == Rank.KING &&
+        cards.last().rank == Rank.ACE &&
+        sameSuitRun(cards)
+
+/**
+ * A hundred and four cards drawn from [suits] suits.
+ *
+ * One suit means eight identical spade packs; four means two of each ordinary
+ * suit. The count never changes, so the deal is the same shape whatever the
+ * table chose.
+ */
+fun spiderDeck(suits: Int): List<Card> {
+    val used = Suit.entries.take(suits)
+    val copies = 8 / suits
+    return used.flatMap { suit ->
+        List(copies) { Rank.standard.map { Card(it, suit) } }.flatten()
+    }
+}

app/src/main/java/org/prolibertate/games/game/spider/SpiderRules.kt

@@ -0,0 +1,177 @@
+package org.prolibertate.games.game.spider
+
+import kotlinx.serialization.encodeToString
+import kotlinx.serialization.json.Json
+import org.prolibertate.games.game.GameCatalog
+import org.prolibertate.games.game.cards.Card
+import org.prolibertate.games.game.cards.shuffledWith
+import org.prolibertate.games.game.engine.GameRules
+import org.prolibertate.games.game.engine.TableConfig
+import kotlin.random.Random
+
+/**
+ * Spider as a pure state machine. See RULES-spider.md.
+ */
+object SpiderRules : GameRules<SpiderState, SpiderMove> {
+
+    override val gameId: String = GameCatalog.SPIDER
+    const val SOLO_SEAT: Int = 0
+
+    private val json = Json {
+        ignoreUnknownKeys = true
+        encodeDefaults = true
+    }
+
+    override fun initialState(config: TableConfig): SpiderState {
+        val options = json.decodeFromString<SpiderOptions>(config.optionsJson)
+        require(config.seats.size == 1) { "Spider seats one, not ${config.seats.size}" }
+        return deal(options, config.seed)
+    }
+
+    private fun deal(options: SpiderOptions, seed: Long): SpiderState {
+        val deck = spiderDeck(options.suits).shuffledWith(Random(seed)).toMutableList()
+        // Fifty-four cards go out: six to the first four columns, five to the
+        // rest. The remaining fifty are the five rows still to come.
+        val piles = (0 until COLUMNS).map { index ->
+            val size = if (index < 4) 6 else 5
+            val taken = List(size) { deck.removeAt(deck.size - 1) }
+            SpiderPile(faceDown = taken.dropLast(1), faceUp = listOf(taken.last()))
+        }
+        return SpiderState(
+            options = options,
+            seed = seed,
+            stock = deck.toList(),
+            tableau = piles,
+            completed = 0,
+            moves = 0,
+            log = listOf("Dealt, ${options.suits} suit${if (options.suits == 1) "" else "s"}."),
+        )
+    }
+
+    override fun currentSeat(state: SpiderState): Int? =
+        if (isFinished(state)) null else SOLO_SEAT
+
+    /** The longest same-suit descending run on the end of a column. */
+    fun movableTail(pile: SpiderPile): List<Card> {
+        if (pile.faceUp.isEmpty()) return emptyList()
+        var take = 1
+        while (take < pile.faceUp.size) {
+            if (!sameSuitRun(pile.faceUp.takeLast(take + 1))) break
+            take++
+        }
+        return pile.faceUp.takeLast(take)
+    }
+
+    override fun legalMoves(state: SpiderState, seat: Int): List<SpiderMove> {
+        if (seat != SOLO_SEAT || state.isWon) return emptyList()
+        val moves = mutableListOf<SpiderMove>()
+        if (state.canDeal) moves += DealRow
+
+        state.tableau.forEachIndexed { from, pile ->
+            val tail = movableTail(pile)
+            for (count in 1..tail.size) {
+                val run = tail.takeLast(count)
+                val head = run.first()
+                state.tableau.indices.forEach { to ->
+                    if (to == from) return@forEach
+                    val target = state.tableau[to]
+                    val fits = target.top?.let { landsOn(head, it) } ?: true
+                    if (!fits) return@forEach
+                    // Emptying one column only to fill another gains nothing.
+                    if (target.isEmpty && pile.faceDown.isEmpty() && count == pile.faceUp.size) {
+                        return@forEach
+                    }
+                    moves += MoveRun(from, to, count)
+                }
+            }
+        }
+        return moves
+    }
+
+    override fun applyMove(state: SpiderState, seat: Int, move: SpiderMove): SpiderState {
+        require(seat == SOLO_SEAT) { "Spider has one seat" }
+        require(legalMoves(state, seat).contains(move)) { "$move is not legal here" }
+        val next = when (move) {
+            DealRow -> dealRow(state)
+            is MoveRun -> moveRun(state, move)
+        }
+        return next.copy(
+            moves = state.moves + 1,
+            log = if (next.isWon) next.log + "Out, in ${state.moves + 1} moves." else next.log,
+        )
+    }
+
+    private fun dealRow(state: SpiderState): SpiderState {
+        var stock = state.stock
+        val piles = state.tableau.map { pile ->
+            val card = stock.lastOrNull() ?: return@map pile
+            stock = stock.dropLast(1)
+            pile.copy(faceUp = pile.faceUp + card)
+        }
+        // A dealt row can complete a run in any column it landed on.
+        return sweep(state.copy(stock = stock, tableau = piles), piles.indices.toList())
+    }
+
+    private fun moveRun(state: SpiderState, move: MoveRun): SpiderState {
+        val source = state.tableau[move.from]
+        val run = source.faceUp.takeLast(move.count)
+        val left = source.faceUp.dropLast(move.count)
+        val stripped = if (left.isEmpty() && source.faceDown.isNotEmpty()) {
+            SpiderPile(source.faceDown.dropLast(1), listOf(source.faceDown.last()))
+        } else {
+            source.copy(faceUp = left)
+        }
+        val target = state.tableau[move.to]
+        val piles = state.tableau.toMutableList().also {
+            it[move.from] = stripped
+            it[move.to] = target.copy(faceUp = target.faceUp + run)
+        }
+        return sweep(state.copy(tableau = piles), listOf(move.to))
+    }
+
+    /**
+     * Sends away any king-to-ace run finished by the last move.
+     *
+     * Only the columns that changed are looked at, and only their ends: a
+     * complete run can only ever be sitting on the bottom of a pile, because
+     * anything laid on an ace would have to be lower than one.
+     */
+    private fun sweep(state: SpiderState, touched: List<Int>): SpiderState {
+        var piles = state.tableau
+        var completed = state.completed
+        var notes = state.log
+        touched.forEach { index ->
+            val pile = piles[index]
+            if (pile.faceUp.size < RUN_LENGTH) return@forEach
+            if (!isCompleteRun(pile.faceUp.takeLast(RUN_LENGTH))) return@forEach
+            val left = pile.faceUp.dropLast(RUN_LENGTH)
+            val stripped = if (left.isEmpty() && pile.faceDown.isNotEmpty()) {
+                SpiderPile(pile.faceDown.dropLast(1), listOf(pile.faceDown.last()))
+            } else {
+                pile.copy(faceUp = left)
+            }
+            piles = piles.toMutableList().also { it[index] = stripped }
+            completed++
+            notes = notes + "A run went away — $completed of $RUNS_TO_WIN."
+        }
+        return state.copy(tableau = piles, completed = completed, log = notes)
+    }
+
+    override fun isFinished(state: SpiderState): Boolean =
+        state.isWon || legalMoves(state, SOLO_SEAT).isEmpty()
+
+    override fun summary(state: SpiderState): String = when {
+        state.isWon -> "All eight runs, in ${state.moves} moves"
+        isFinished(state) -> "Blocked with ${state.completed} runs away"
+        else -> "${state.completed} of $RUNS_TO_WIN runs away"
+    }
+
+    override fun viewFor(state: SpiderState, seat: Int): SpiderState = state
+
+    override fun encodeState(state: SpiderState): String = json.encodeToString(state)
+    override fun decodeState(json: String): SpiderState = this.json.decodeFromString(json)
+    override fun encodeMove(move: SpiderMove): String = json.encodeToString(move)
+    override fun decodeMove(json: String): SpiderMove = this.json.decodeFromString(json)
+
+    fun restart(state: SpiderState): SpiderState = deal(state.options, state.seed)
+}

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

@@ -42,6 +42,9 @@ import org.prolibertate.games.game.euchre.EuchreOptions
 import org.prolibertate.games.game.golf.GolfOptions
 import org.prolibertate.games.game.hearts.HeartsOptions
 import org.prolibertate.games.game.klondike.KlondikeOptions
+import org.prolibertate.games.game.freecell.FreeCellOptions
+import org.prolibertate.games.game.pyramid.PyramidOptions
+import org.prolibertate.games.game.spider.SpiderOptions
 import org.prolibertate.games.game.yahtzee.YahtzeeOptions
 import org.prolibertate.games.game.pegsolitaire.PegBoard
 import org.prolibertate.games.game.pegsolitaire.PegGoal
@@ -98,6 +101,9 @@ fun GameSetupScreen(
     var pegs by remember { mutableStateOf(PegSolitaireOptions()) }
     var yahtzee by remember { mutableStateOf(YahtzeeOptions()) }
     var klondike by remember { mutableStateOf(KlondikeOptions()) }
+    var freecell by remember { mutableStateOf(FreeCellOptions()) }
+    var spider by remember { mutableStateOf(SpiderOptions()) }
+    var pyramid by remember { mutableStateOf(PyramidOptions()) }
     // Not an engine option: which seat the local player takes. Seat 0 is
     // always White, so choosing Black means sitting in seat 1.
     var playWhite by remember { mutableStateOf(true) }
@@ -125,6 +131,9 @@ fun GameSetupScreen(
         GameCatalog.PEG_SOLITAIRE -> setupJson.encodeToString(pegs)
         GameCatalog.YAHTZEE -> setupJson.encodeToString(yahtzee)
         GameCatalog.KLONDIKE -> setupJson.encodeToString(klondike)
+        GameCatalog.FREECELL -> setupJson.encodeToString(freecell)
+        GameCatalog.SPIDER -> setupJson.encodeToString(spider)
+        GameCatalog.PYRAMID -> setupJson.encodeToString(pyramid)
         else -> "{}"
     }
     val seatCount = seatCountFor(descriptor.id, optionsJson)
@@ -184,6 +193,12 @@ fun GameSetupScreen(
 
                 GameCatalog.KLONDIKE -> KlondikeOptionsEditor(klondike) { klondike = it }
 
+                GameCatalog.FREECELL -> FreeCellOptionsEditor(freecell) { freecell = it }
+
+                GameCatalog.SPIDER -> SpiderOptionsEditor(spider) { spider = it }
+
+                GameCatalog.PYRAMID -> PyramidOptionsEditor(pyramid) { pyramid = it }
+
                 else -> Text("No options yet for this game.")
             }
 
@@ -1078,3 +1093,51 @@ private fun KlondikeOptionsEditor(options: KlondikeOptions, onChange: (KlondikeO
         )
     }
 }
+
+@Composable
+private fun FreeCellOptionsEditor(options: FreeCellOptions, onChange: (FreeCellOptions) -> Unit) {
+    Column(verticalArrangement = Arrangement.spacedBy(8.dp)) {
+        ChipRow(
+            label = "Free cells",
+            values = (1..6).toList(),
+            selected = options.freeCells,
+            display = { "$it" },
+            onSelect = { onChange(options.copy(freeCells = it)) },
+        )
+        ToggleRow(
+            title = "Move a run in one go",
+            subtitle = "The rules move a run one card at a time through the cells. This " +
+                "does the shuffling for you, which is bookkeeping rather than a decision.",
+            checked = options.allowSupermoves,
+            onChange = { onChange(options.copy(allowSupermoves = it)) },
+        )
+    }
+}
+
+@Composable
+private fun SpiderOptionsEditor(options: SpiderOptions, onChange: (SpiderOptions) -> Unit) {
+    ChipRow(
+        label = "Suits",
+        values = listOf(1, 2, 4),
+        selected = options.suits,
+        display = {
+            when (it) {
+                1 -> "One — a pastime"
+                2 -> "Two"
+                else -> "Four — a fight"
+            }
+        },
+        onSelect = { onChange(options.copy(suits = it)) },
+    )
+}
+
+@Composable
+private fun PyramidOptionsEditor(options: PyramidOptions, onChange: (PyramidOptions) -> Unit) {
+    ChipRow(
+        label = "Turns through the pack",
+        values = listOf(0, 1, 2, 3),
+        selected = options.redeals,
+        display = { if (it == 0) "One pass only" else "$it turns back" },
+        onSelect = { onChange(options.copy(redeals = it)) },
+    )
+}

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

@@ -29,6 +29,16 @@ import org.prolibertate.games.game.euchre.EuchreMove
 import org.prolibertate.games.game.euchre.EuchrePhase
 import org.prolibertate.games.game.euchre.EuchreRules
 import org.prolibertate.games.game.euchre.EuchreState
+import org.prolibertate.games.game.freecell.FreeCellMove
+import org.prolibertate.games.game.freecell.FreeCellRules
+import org.prolibertate.games.game.freecell.FreeCellState
+import org.prolibertate.games.game.pyramid.PyramidMove
+import org.prolibertate.games.game.pyramid.PyramidRules
+import org.prolibertate.games.game.pyramid.PyramidState
+import org.prolibertate.games.game.solitaire.FirstLegalAi
+import org.prolibertate.games.game.spider.SpiderMove
+import org.prolibertate.games.game.spider.SpiderRules
+import org.prolibertate.games.game.spider.SpiderState
 import org.prolibertate.games.game.klondike.KlondikeAi
 import org.prolibertate.games.game.klondike.KlondikeMove
 import org.prolibertate.games.game.klondike.KlondikeRules
@@ -102,13 +112,16 @@ import org.prolibertate.games.ui.game.ChessScreen
 import org.prolibertate.games.ui.game.CrazyEightsScreen
 import org.prolibertate.games.ui.game.CribbageScreen
 import org.prolibertate.games.ui.game.HeartsScreen
+import org.prolibertate.games.ui.game.FreeCellScreen
 import org.prolibertate.games.ui.game.KlondikeScreen
+import org.prolibertate.games.ui.game.PyramidScreen
 import org.prolibertate.games.ui.game.EuchreScreen
 import org.prolibertate.games.ui.game.GolfScreen
 import org.prolibertate.games.ui.game.KaiserScreen
 import org.prolibertate.games.ui.game.MastermindScreen
 import org.prolibertate.games.ui.game.MorrisScreen
 import org.prolibertate.games.ui.game.PegSolitaireScreen
+import org.prolibertate.games.ui.game.SpiderScreen
 import org.prolibertate.games.ui.game.YahtzeeScreen
 import org.prolibertate.games.ui.game.PiratesScreen
 import org.prolibertate.games.ui.game.PresidentScreen
@@ -559,6 +572,57 @@ fun PlayScreen(
             )
         }
 
+        GameCatalog.FREECELL -> {
+            var generation by remember(route) { mutableIntStateOf(0) }
+            val controller = remember(route, generation) {
+                MatchController<FreeCellState, FreeCellMove>(
+                    rules = FreeCellRules,
+                    ai = FirstLegalAi(),
+                    config = route.config,
+                    scope = scope,
+                    role = role,
+                    localSeats = setOf(route.localSeat),
+                    primarySeat = route.localSeat,
+                )
+            }
+            StartMatch(env, controller, route)
+            FreeCellScreen(controller = controller, onRestart = { generation++ }, onExit = onExit)
+        }
+
+        GameCatalog.SPIDER -> {
+            var generation by remember(route) { mutableIntStateOf(0) }
+            val controller = remember(route, generation) {
+                MatchController<SpiderState, SpiderMove>(
+                    rules = SpiderRules,
+                    ai = FirstLegalAi(),
+                    config = route.config,
+                    scope = scope,
+                    role = role,
+                    localSeats = setOf(route.localSeat),
+                    primarySeat = route.localSeat,
+                )
+            }
+            StartMatch(env, controller, route)
+            SpiderScreen(controller = controller, onRestart = { generation++ }, onExit = onExit)
+        }
+
+        GameCatalog.PYRAMID -> {
+            var generation by remember(route) { mutableIntStateOf(0) }
+            val controller = remember(route, generation) {
+                MatchController<PyramidState, PyramidMove>(
+                    rules = PyramidRules,
+                    ai = FirstLegalAi(),
+                    config = route.config,
+                    scope = scope,
+                    role = role,
+                    localSeats = setOf(route.localSeat),
+                    primarySeat = route.localSeat,
+                )
+            }
+            StartMatch(env, controller, route)
+            PyramidScreen(controller = controller, onRestart = { generation++ }, onExit = onExit)
+        }
+
         GameCatalog.MORRIS -> {
             val controller = remember(route) {
                 MatchController<MorrisState, MorrisMove>(

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

@@ -0,0 +1,96 @@
+package org.prolibertate.games.ui.game
+
+import androidx.compose.foundation.BorderStroke
+import androidx.compose.foundation.background
+import androidx.compose.foundation.border
+import androidx.compose.foundation.clickable
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.height
+import androidx.compose.foundation.layout.width
+import androidx.compose.foundation.shape.RoundedCornerShape
+import androidx.compose.material3.AlertDialog
+import androidx.compose.material3.Text
+import androidx.compose.material3.TextButton
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.unit.Dp
+import androidx.compose.ui.unit.dp
+import org.prolibertate.games.ui.common.CARD_ASPECT
+import org.prolibertate.games.ui.theme.FeltGreenDark
+import org.prolibertate.games.ui.theme.Parchment
+import org.prolibertate.games.ui.theme.WallaceGold
+
+/**
+ * The furniture every patience table needs.
+ *
+ * FreeCell, Spider and Pyramid lay their cards out quite differently but they
+ * are all made of the same three things: a place a card sits, an empty place
+ * that can still be tapped into, and the two dialogs for leaving. Klondike keeps
+ * its own copies — it was written first and its layout constants are tuned to
+ * seven columns — but nothing new needs to repeat them.
+ */
+val TABLE_CARD_WIDTH: Dp = 44.dp
+val TABLE_CARD_HEIGHT: Dp = TABLE_CARD_WIDTH / CARD_ASPECT
+
+/** Overlapped by a third, which hides as little as a stack can afford to. */
+val TABLE_STACK_STEP: Dp = TABLE_CARD_HEIGHT * 2f / 3f
+
+@Composable
+fun TableSlot(
+    highlighted: Boolean,
+    onClick: () -> Unit,
+    modifier: Modifier = Modifier,
+    width: Dp = TABLE_CARD_WIDTH,
+    content: @Composable () -> Unit,
+) {
+    Box(
+        modifier = modifier
+            .width(width)
+            .border(
+                border = BorderStroke(if (highlighted) 3.dp else 0.dp, WallaceGold),
+                shape = RoundedCornerShape(4.dp),
+            )
+            .clickable { onClick() },
+    ) {
+        content()
+    }
+}
+
+/** A place with no card on it, drawn so it is still somewhere to aim at. */
+@Composable
+fun EmptySpace(label: String = "", width: Dp = TABLE_CARD_WIDTH) {
+    Box(
+        modifier = Modifier
+            .width(width)
+            .height(width / CARD_ASPECT)
+            .background(FeltGreenDark, RoundedCornerShape(4.dp)),
+        contentAlignment = Alignment.Center,
+    ) {
+        if (label.isNotEmpty()) {
+            Text(label, color = Parchment.copy(alpha = 0.5f))
+        }
+    }
+}
+
+@Composable
+fun PatienceEndDialog(what: String, onEnd: () -> Unit, onKeepPlaying: () -> Unit) {
+    AlertDialog(
+        onDismissRequest = onKeepPlaying,
+        title = { Text("End this game?") },
+        text = { Text(what) },
+        confirmButton = { TextButton(onClick = onEnd) { Text("End the game") } },
+        dismissButton = { TextButton(onClick = onKeepPlaying) { Text("Keep playing") } },
+    )
+}
+
+@Composable
+fun PatienceLeftDialog(notice: String, onExit: () -> Unit, onStay: () -> Unit) {
+    AlertDialog(
+        onDismissRequest = onStay,
+        title = { Text("The game has ended") },
+        text = { Text(notice) },
+        confirmButton = { TextButton(onClick = onExit) { Text("Leave the game") } },
+        dismissButton = { TextButton(onClick = onStay) { Text("Look at the table") } },
+    )
+}

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

@@ -0,0 +1,188 @@
+package org.prolibertate.games.ui.game
+
+import androidx.compose.foundation.horizontalScroll
+import androidx.compose.foundation.layout.Arrangement
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.Row
+import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.height
+import androidx.compose.foundation.layout.offset
+import androidx.compose.foundation.layout.width
+import androidx.compose.foundation.rememberScrollState
+import androidx.compose.foundation.verticalScroll
+import androidx.compose.material3.Button
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.Text
+import androidx.compose.material3.TextButton
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.collectAsState
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.runtime.setValue
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.text.font.FontWeight
+import androidx.compose.ui.unit.dp
+import org.prolibertate.games.game.cards.Suit
+import org.prolibertate.games.game.freecell.FreeCellMove
+import org.prolibertate.games.game.freecell.FreeCellState
+import org.prolibertate.games.game.freecell.MoveTo
+import org.prolibertate.games.game.freecell.Place
+import org.prolibertate.games.net.MatchController
+import org.prolibertate.games.ui.ScreenScaffold
+import org.prolibertate.games.ui.common.PlayingCardView
+
+private const val TITLE = "FreeCell"
+
+/**
+ * The FreeCell table.
+ *
+ * Cells on the left, homes on the right, eight columns below — the standard
+ * arrangement, and the one that makes the cells read as somewhere to put things
+ * rather than somewhere cards come from. Everything is face up from the first
+ * move, so the whole game is on the screen and the only thing hidden is what to
+ * do about it.
+ */
+@Composable
+fun FreeCellScreen(
+    controller: MatchController<FreeCellState, FreeCellMove>,
+    onRestart: () -> Unit,
+    onExit: () -> Unit,
+) {
+    val state by controller.state.collectAsState()
+    val legal by controller.legalMoves.collectAsState()
+    val abandoned by controller.abandoned.collectAsState()
+
+    var held by remember { mutableStateOf<Pair<Place, Int>?>(null) }
+    var confirmingEnd by remember { mutableStateOf(false) }
+
+    val endGameAction: @Composable () -> Unit = {
+        TextButton(onClick = { confirmingEnd = true }) { Text("End game") }
+    }
+
+    val current = state
+    if (current == null) {
+        ScreenScaffold(title = TITLE, onBack = onExit, actions = endGameAction) { modifier ->
+            Box(modifier, contentAlignment = Alignment.Center) { Text("Dealing…") }
+            abandoned?.let { PatienceLeftDialog(it, onExit, controller::dismissAbandoned) }
+            if (confirmingEnd) {
+                PatienceEndDialog("The deal is left as it stands.", onExit) { confirmingEnd = false }
+            }
+        }
+        return
+    }
+
+    val moves = legal.filterIsInstance<MoveTo>()
+    val finished = legal.isEmpty()
+    val targets = held?.let { (from, count) ->
+        moves.filter { it.from == from && it.count == count }.map { it.to }.toSet()
+    }.orEmpty()
+    val sources = moves.map { it.from to it.count }.toSet()
+
+    fun take(place: Place, count: Int) {
+        val inHand = held
+        held = when {
+            inHand != null && targets.contains(place) -> {
+                controller.submit(MoveTo(inHand.first, place, inHand.second))
+                null
+            }
+
+            inHand?.first == place -> null
+            sources.contains(place to count) -> place to count
+            else -> null
+        }
+    }
+
+    ScreenScaffold(title = TITLE, onBack = onExit, actions = endGameAction) { modifier ->
+        Column(
+            modifier = modifier.verticalScroll(rememberScrollState()),
+            verticalArrangement = Arrangement.spacedBy(10.dp),
+        ) {
+            Text(
+                text = when {
+                    current.isWon -> "Out, in ${current.moves} moves."
+                    finished -> "Blocked — nothing left to try."
+                    held != null -> "Tap where it goes."
+                    else -> "${current.foundations.sumOf { it.size }} of 52 home, " +
+                        "${current.freeCellCount} cells free."
+                },
+                fontWeight = FontWeight.Bold,
+            )
+
+            Row(
+                modifier = Modifier.fillMaxWidth().horizontalScroll(rememberScrollState()),
+                horizontalArrangement = Arrangement.spacedBy(6.dp),
+            ) {
+                current.cells.forEachIndexed { index, card ->
+                    TableSlot(
+                        highlighted = held?.first == Place.cell(index) ||
+                            targets.contains(Place.cell(index)),
+                        onClick = { take(Place.cell(index), 1) },
+                    ) {
+                        card?.let { PlayingCardView(card = it, width = TABLE_CARD_WIDTH) }
+                            ?: EmptySpace(label = "·")
+                    }
+                }
+                current.foundations.forEachIndexed { index, pile ->
+                    TableSlot(
+                        highlighted = targets.contains(Place.foundation(index)),
+                        onClick = { take(Place.foundation(index), 1) },
+                    ) {
+                        pile.lastOrNull()?.let { PlayingCardView(card = it, width = TABLE_CARD_WIDTH) }
+                            ?: EmptySpace(label = Suit.entries[index].symbol)
+                    }
+                }
+            }
+
+            Row(
+                modifier = Modifier.fillMaxWidth().horizontalScroll(rememberScrollState()),
+                horizontalArrangement = Arrangement.spacedBy(6.dp),
+                verticalAlignment = Alignment.Top,
+            ) {
+                current.tableau.forEachIndexed { index, column ->
+                    if (column.isEmpty()) {
+                        TableSlot(
+                            highlighted = targets.contains(Place.column(index)),
+                            onClick = { take(Place.column(index), 1) },
+                        ) { EmptySpace() }
+                    } else {
+                        Box(
+                            modifier = Modifier
+                                .width(TABLE_CARD_WIDTH)
+                                .height(TABLE_CARD_HEIGHT + TABLE_STACK_STEP * (column.size - 1)),
+                        ) {
+                            column.forEachIndexed { depth, card ->
+                                // Taking a card takes everything resting on it.
+                                val count = column.size - depth
+                                TableSlot(
+                                    modifier = Modifier.offset(y = TABLE_STACK_STEP * depth),
+                                    highlighted = held == (Place.column(index) to count) ||
+                                        (depth == column.lastIndex && targets.contains(Place.column(index))),
+                                    onClick = { take(Place.column(index), count) },
+                                ) { PlayingCardView(card = card, width = TABLE_CARD_WIDTH) }
+                            }
+                        }
+                    }
+                }
+            }
+
+            if (finished) {
+                Row(horizontalArrangement = Arrangement.spacedBy(8.dp)) {
+                    Button(onClick = onRestart) { Text("Deal again") }
+                    TextButton(onClick = onExit) { Text("Leave") }
+                }
+            }
+
+            current.log.takeLast(2).forEach {
+                Text(it, style = MaterialTheme.typography.bodySmall)
+            }
+        }
+
+        abandoned?.let { PatienceLeftDialog(it, onExit, controller::dismissAbandoned) }
+        if (confirmingEnd) {
+            PatienceEndDialog("The deal is left as it stands.", onExit) { confirmingEnd = false }
+        }
+    }
+}

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

@@ -9,8 +9,9 @@ import androidx.compose.foundation.layout.Arrangement
 import androidx.compose.foundation.layout.Box
 import androidx.compose.foundation.layout.Column
 import androidx.compose.foundation.layout.Row
-import androidx.compose.foundation.layout.aspectRatio
 import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.height
+import androidx.compose.foundation.layout.offset
 import androidx.compose.foundation.layout.width
 import androidx.compose.foundation.rememberScrollState
 import androidx.compose.foundation.shape.RoundedCornerShape
@@ -31,15 +32,18 @@ import androidx.compose.ui.Modifier
 import androidx.compose.ui.text.font.FontWeight
 import androidx.compose.ui.unit.Dp
 import androidx.compose.ui.unit.dp
+import org.prolibertate.games.game.cards.Card
 import org.prolibertate.games.game.klondike.Draw
 import org.prolibertate.games.game.klondike.KlondikeMove
 import org.prolibertate.games.game.klondike.KlondikeState
 import org.prolibertate.games.game.klondike.MoveCards
 import org.prolibertate.games.game.klondike.Redeal
 import org.prolibertate.games.game.klondike.Spot
+import org.prolibertate.games.game.klondike.TableauPile
 import org.prolibertate.games.game.klondike.foundationSuit
 import org.prolibertate.games.net.MatchController
 import org.prolibertate.games.ui.ScreenScaffold
+import org.prolibertate.games.ui.common.CARD_ASPECT
 import org.prolibertate.games.ui.common.CardBackView
 import org.prolibertate.games.ui.common.PlayingCardView
 import org.prolibertate.games.ui.theme.FeltGreenDark
@@ -47,18 +51,39 @@ import org.prolibertate.games.ui.theme.Parchment
 import org.prolibertate.games.ui.theme.WallaceGold
 
 private const val TITLE = "Klondike"
-private val CARD_WIDTH: Dp = 40.dp
+
+private val CARD_WIDTH: Dp = 44.dp
+private val CARD_HEIGHT: Dp = CARD_WIDTH / CARD_ASPECT
+
+/**
+ * How far down each card in a column sits from the one above it.
+ *
+ * Two thirds of a card, so each is overlapped by a third. That is the most that
+ * can be hidden while every card still shows its rank and suit, and it is what
+ * keeps a column of thirteen on the screen instead of running off the bottom.
+ */
+private val STACK_STEP: Dp = CARD_HEIGHT * 2f / 3f
+
+/** The same overlap sideways, for the three cards turned off the stock. */
+private val FAN_STEP: Dp = CARD_WIDTH * 2f / 3f
+
+/** At most three are ever turned at once, so at most three are ever fanned. */
+private const val MAX_FANNED = 3
 
 /**
  * The patience table.
  *
- * Play is tap-to-take then tap-to-put, rather than dragging: on a phone a drag
+ * Laid out the way a real one is: the homes along the top where cards are going,
- * over seven columns of overlapping cards is mostly a test of aim. Tapping a
+ * the columns filling the middle, and the pack in the bottom corner under your
- * face-up card takes it and everything sitting on it, so a run travels the way
+ * hand. Columns overlap by a third so a long one still fits, and the cards
- * it would on a table.
+ * turned off the stock fan sideways by the same third so all three can be seen
+ * rather than only the one on top.
  *
- * Which taps do anything is read straight off the legal moves the rules offer,
+ * Play is tap-to-take then tap-to-put rather than dragging: across seven columns
- * so the screen never has to know why a move is allowed — only that it is.
+ * of overlapping cards on a phone, a drag is mostly a test of aim. Tapping a
+ * face-up card takes it and everything resting on it, so a run travels the way
+ * it would on a table. Which taps do anything is read off the legal moves the
+ * rules offer, so the screen never has to know why a move is allowed.
  */
 @Composable
 fun KlondikeScreen(
@@ -92,7 +117,6 @@ fun KlondikeScreen(
     val canRedeal = legal.contains(Redeal)
     val finished = legal.isEmpty()
 
-    // Where the cards in hand could go, and which spots could be picked up.
     val targets = held?.let { (from, count) ->
         moves.filter { it.from == from && it.count == count }.map { it.to }.toSet()
     }.orEmpty()
@@ -115,7 +139,7 @@ fun KlondikeScreen(
     ScreenScaffold(title = TITLE, onBack = onExit, actions = endGameAction) { modifier ->
         Column(
             modifier = modifier.verticalScroll(rememberScrollState()),
-            verticalArrangement = Arrangement.spacedBy(8.dp),
+            verticalArrangement = Arrangement.spacedBy(10.dp),
         ) {
             Text(
                 text = when {
@@ -127,26 +151,8 @@ fun KlondikeScreen(
                 fontWeight = FontWeight.Bold,
             )
 
+            // The homes, along the top where they are being filled towards.
             Row(horizontalArrangement = Arrangement.spacedBy(6.dp)) {
-                // Stock, waste, and the four homes across the top.
-                Slot(
-                    highlighted = false,
-                    onClick = { if (canDraw) controller.submit(Draw) else if (canRedeal) controller.submit(Redeal) },
-                ) {
-                    if (current.stock.isNotEmpty()) {
-                        CardBackView(width = CARD_WIDTH)
-                    } else {
-                        Empty(label = if (canRedeal) "↻" else "")
-                    }
-                }
-                Slot(
-                    highlighted = held?.first == Spot.waste,
-                    onClick = { take(Spot.waste, 1) },
-                ) {
-                    current.waste.lastOrNull()
-                        ?.let { PlayingCardView(card = it, width = CARD_WIDTH) }
-                        ?: Empty()
-                }
                 current.foundations.forEachIndexed { index, pile ->
                     Slot(
                         highlighted = targets.contains(Spot.foundation(index)),
@@ -162,28 +168,43 @@ fun KlondikeScreen(
             Row(
                 modifier = Modifier.fillMaxWidth().horizontalScroll(rememberScrollState()),
                 horizontalArrangement = Arrangement.spacedBy(6.dp),
+                verticalAlignment = Alignment.Top,
             ) {
                 current.tableau.forEachIndexed { index, pile ->
-                    Column(verticalArrangement = Arrangement.spacedBy(2.dp)) {
+                    ColumnOfCards(
-                        if (pile.isEmpty) {
+                        pile = pile,
-                            Slot(
+                        held = held,
-                                highlighted = targets.contains(Spot.tableau(index)),
+                        index = index,
-                                onClick = { take(Spot.tableau(index), 1) },
+                        isTarget = targets.contains(Spot.tableau(index)),
-                            ) { Empty() }
+                        onTap = { count -> take(Spot.tableau(index), count) },
-                        }
+                    )
-                        pile.faceDown.forEach { CardBackView(width = CARD_WIDTH) }
+                }
-                        pile.faceUp.forEachIndexed { depth, card ->
+            }
-                            // Taking a card takes everything resting on it, so
+
-                            // the count is however many are below it in the run.
+            // The pack sits at the bottom left, under the hand that turns it.
-                            val count = pile.faceUp.size - depth
+            Row(horizontalArrangement = Arrangement.spacedBy(6.dp)) {
-                            Slot(
+                Slot(
-                                highlighted = held == (Spot.tableau(index) to count) ||
+                    highlighted = false,
-                                    (depth == pile.faceUp.lastIndex && targets.contains(Spot.tableau(index))),
+                    onClick = {
-                                onClick = { take(Spot.tableau(index), count) },
+                        if (canDraw) {
-                            ) { PlayingCardView(card = card, width = CARD_WIDTH) }
+                            controller.submit(Draw)
+                        } else if (canRedeal) {
+                            controller.submit(Redeal)
                         }
+                    },
+                ) {
+                    if (current.stock.isNotEmpty()) {
+                        CardBackView(width = CARD_WIDTH)
+                    } else {
+                        Empty(label = if (canRedeal) "↻" else "")
                     }
                 }
+                WasteFan(
+                    waste = current.waste,
+                    fanned = minOf(current.options.drawCount, MAX_FANNED),
+                    highlighted = held?.first == Spot.waste,
+                    onTap = { take(Spot.waste, 1) },
+                )
             }
 
             if (finished) {
@@ -203,10 +224,91 @@ fun KlondikeScreen(
     }
 }
 
+/**
+ * One column, overlapped by a third.
+ *
+ * Absolute offsets rather than negative spacing: the height has to be worked out
+ * anyway so the column reserves the right room, and once that is known placing
+ * each card is the simpler half.
+ */
 @Composable
-private fun Slot(highlighted: Boolean, onClick: () -> Unit, content: @Composable () -> Unit) {
+private fun ColumnOfCards(
+    pile: TableauPile,
+    held: Pair<Spot, Int>?,
+    index: Int,
+    isTarget: Boolean,
+    onTap: (Int) -> Unit,
+) {
+    val total = pile.faceDown.size + pile.faceUp.size
+    if (total == 0) {
+        Slot(highlighted = isTarget, onClick = { onTap(1) }) { Empty() }
+        return
+    }
     Box(
         modifier = Modifier
+            .width(CARD_WIDTH)
+            .height(CARD_HEIGHT + STACK_STEP * (total - 1)),
+    ) {
+        pile.faceDown.forEachIndexed { depth, _ ->
+            CardBackView(
+                width = CARD_WIDTH,
+                modifier = Modifier.offset(y = STACK_STEP * depth),
+            )
+        }
+        pile.faceUp.forEachIndexed { depth, card ->
+            // Taking a card takes everything resting on it.
+            val count = pile.faceUp.size - depth
+            val row = pile.faceDown.size + depth
+            Slot(
+                modifier = Modifier.offset(y = STACK_STEP * row),
+                highlighted = held == (Spot.tableau(index) to count) ||
+                    (depth == pile.faceUp.lastIndex && isTarget),
+                onClick = { onTap(count) },
+            ) { PlayingCardView(card = card, width = CARD_WIDTH) }
+        }
+    }
+}
+
+/**
+ * The cards turned off the stock, fanned sideways.
+ *
+ * Drawing three and showing one would hide two cards the player is entitled to
+ * see — they are face up on the table. Only the last is playable, which the
+ * rules already enforce; the other two are there to be read.
+ */
+@Composable
+private fun WasteFan(
+    waste: List<Card>,
+    fanned: Int,
+    highlighted: Boolean,
+    onTap: () -> Unit,
+) {
+    val shown = waste.takeLast(fanned)
+    if (shown.isEmpty()) {
+        Slot(highlighted = false, onClick = onTap) { Empty() }
+        return
+    }
+    Box(modifier = Modifier.width(CARD_WIDTH + FAN_STEP * (shown.size - 1))) {
+        shown.forEachIndexed { position, card ->
+            val isTop = position == shown.lastIndex
+            Slot(
+                modifier = Modifier.offset(x = FAN_STEP * position),
+                highlighted = isTop && highlighted,
+                onClick = { if (isTop) onTap() },
+            ) { PlayingCardView(card = card, width = CARD_WIDTH) }
+        }
+    }
+}
+
+@Composable
+private fun Slot(
+    highlighted: Boolean,
+    onClick: () -> Unit,
+    modifier: Modifier = Modifier,
+    content: @Composable () -> Unit,
+) {
+    Box(
+        modifier = modifier
             .width(CARD_WIDTH)
             .border(
                 border = BorderStroke(if (highlighted) 3.dp else 0.dp, WallaceGold),
@@ -224,7 +326,7 @@ private fun Empty(label: String = "") {
     Box(
         modifier = Modifier
             .width(CARD_WIDTH)
-            .aspectRatio(0.7f)
+            .height(CARD_HEIGHT)
             .background(FeltGreenDark, RoundedCornerShape(4.dp)),
         contentAlignment = Alignment.Center,
     ) {

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

@@ -0,0 +1,260 @@
+package org.prolibertate.games.ui.game
+
+import androidx.compose.foundation.layout.Arrangement
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.Row
+import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.height
+import androidx.compose.foundation.layout.offset
+import androidx.compose.foundation.layout.width
+import androidx.compose.foundation.rememberScrollState
+import androidx.compose.foundation.verticalScroll
+import androidx.compose.material3.Button
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.Text
+import androidx.compose.material3.TextButton
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.collectAsState
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.runtime.setValue
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.text.font.FontWeight
+import androidx.compose.ui.unit.Dp
+import androidx.compose.ui.unit.dp
+import org.prolibertate.games.game.pyramid.DrawCard
+import org.prolibertate.games.game.pyramid.PYRAMID_SIZE
+import org.prolibertate.games.game.pyramid.PyramidMove
+import org.prolibertate.games.game.pyramid.PyramidSpot
+import org.prolibertate.games.game.pyramid.PyramidState
+import org.prolibertate.games.game.pyramid.PyramidZone
+import org.prolibertate.games.game.pyramid.RecycleWaste
+import org.prolibertate.games.game.pyramid.ROWS
+import org.prolibertate.games.game.pyramid.TakeKing
+import org.prolibertate.games.game.pyramid.TakePair
+import org.prolibertate.games.game.pyramid.rowStart
+import org.prolibertate.games.game.pyramid.valueOf
+import org.prolibertate.games.net.MatchController
+import org.prolibertate.games.ui.ScreenScaffold
+import org.prolibertate.games.ui.common.CardBackView
+import org.prolibertate.games.ui.common.PlayingCardView
+
+private const val TITLE = "Pyramid"
+
+/** Cards are small here: the widest row is seven of them side by side. */
+private val PYRAMID_CARD: Dp = 40.dp
+private val PYRAMID_CARD_HEIGHT: Dp = PYRAMID_CARD * 7f / 5f
+
+/** Rows overlap vertically so the whole pyramid fits above the pack. */
+private val ROW_STEP: Dp = PYRAMID_CARD_HEIGHT * 2f / 3f
+
+/**
+ * The pyramid.
+ *
+ * Drawn as it is dealt: seven rows, each one offset half a card so every card
+ * sits on the two below it, and rows overlapping by a third so all seven fit.
+ * The shape is the rules — a card is only in play once both the cards resting on
+ * it have gone, and being able to see that at a glance is most of playing it.
+ *
+ * Tapping a king takes it alone. Tapping any other card holds it, and tapping
+ * its partner takes the pair; the ones that would pair with what is held are the
+ * only cards that light up.
+ */
+@Composable
+fun PyramidScreen(
+    controller: MatchController<PyramidState, PyramidMove>,
+    onRestart: () -> Unit,
+    onExit: () -> Unit,
+) {
+    val state by controller.state.collectAsState()
+    val legal by controller.legalMoves.collectAsState()
+    val abandoned by controller.abandoned.collectAsState()
+
+    var held by remember { mutableStateOf<PyramidSpot?>(null) }
+    var confirmingEnd by remember { mutableStateOf(false) }
+
+    val endGameAction: @Composable () -> Unit = {
+        TextButton(onClick = { confirmingEnd = true }) { Text("End game") }
+    }
+
+    val current = state
+    if (current == null) {
+        ScreenScaffold(title = TITLE, onBack = onExit, actions = endGameAction) { modifier ->
+            Box(modifier, contentAlignment = Alignment.Center) { Text("Dealing…") }
+            abandoned?.let { PatienceLeftDialog(it, onExit, controller::dismissAbandoned) }
+            if (confirmingEnd) {
+                PatienceEndDialog("The pyramid is left as it stands.", onExit) { confirmingEnd = false }
+            }
+        }
+        return
+    }
+
+    val kings = legal.filterIsInstance<TakeKing>().map { it.spot }.toSet()
+    val pairs = legal.filterIsInstance<TakePair>()
+    val canDraw = legal.contains(DrawCard)
+    val canRedeal = legal.contains(RecycleWaste)
+    val finished = legal.isEmpty()
+
+    // Everything that could pair with what is in hand.
+    val partners = held?.let { spot ->
+        pairs.mapNotNull {
+            when (spot) {
+                it.first -> it.second
+                it.second -> it.first
+                else -> null
+            }
+        }.toSet()
+    }.orEmpty()
+    val pairable = pairs.flatMap { listOf(it.first, it.second) }.toSet()
+
+    fun tap(spot: PyramidSpot) {
+        held = when {
+            kings.contains(spot) && held == null -> {
+                controller.submit(TakeKing(spot))
+                null
+            }
+
+            held != null && partners.contains(spot) -> {
+                controller.submit(TakePair(held!!, spot))
+                null
+            }
+
+            held == spot -> null
+            pairable.contains(spot) -> spot
+            else -> null
+        }
+    }
+
+    ScreenScaffold(title = TITLE, onBack = onExit, actions = endGameAction) { modifier ->
+        Column(
+            modifier = modifier.verticalScroll(rememberScrollState()),
+            verticalArrangement = Arrangement.spacedBy(10.dp),
+        ) {
+            Text(
+                text = when {
+                    current.isWon -> "Pyramid cleared, in ${current.moves} moves."
+                    finished -> "Blocked — nothing pairs to thirteen."
+                    held != null -> "Tap the card that makes it thirteen."
+                    else -> "${current.pyramid.count { it != null }} of $PYRAMID_SIZE left."
+                },
+                fontWeight = FontWeight.Bold,
+            )
+
+            PyramidView(
+                state = current,
+                held = held,
+                kings = kings,
+                partners = partners,
+                pairable = pairable,
+                onTap = ::tap,
+            )
+
+            Row(
+                horizontalArrangement = Arrangement.spacedBy(8.dp),
+                verticalAlignment = Alignment.CenterVertically,
+            ) {
+                TableSlot(
+                    highlighted = false,
+                    width = PYRAMID_CARD,
+                    onClick = {
+                        if (canDraw) {
+                            controller.submit(DrawCard)
+                        } else if (canRedeal) {
+                            controller.submit(RecycleWaste)
+                        }
+                    },
+                ) {
+                    if (current.stock.isNotEmpty()) {
+                        CardBackView(width = PYRAMID_CARD)
+                    } else {
+                        EmptySpace(label = if (canRedeal) "↻" else "", width = PYRAMID_CARD)
+                    }
+                }
+                val wasteSpot = PyramidSpot(PyramidZone.WASTE)
+                TableSlot(
+                    highlighted = held == wasteSpot ||
+                        partners.contains(wasteSpot) ||
+                        kings.contains(wasteSpot),
+                    width = PYRAMID_CARD,
+                    onClick = { tap(wasteSpot) },
+                ) {
+                    current.waste.lastOrNull()
+                        ?.let { PlayingCardView(card = it, width = PYRAMID_CARD) }
+                        ?: EmptySpace(width = PYRAMID_CARD)
+                }
+                Text(
+                    text = "${current.stock.size} in hand, " +
+                        "${current.options.redeals - current.redealsUsed} turns left",
+                    style = MaterialTheme.typography.bodySmall,
+                )
+            }
+
+            if (finished) {
+                Row(horizontalArrangement = Arrangement.spacedBy(8.dp)) {
+                    Button(onClick = onRestart) { Text("Deal again") }
+                    TextButton(onClick = onExit) { Text("Leave") }
+                }
+            }
+
+            current.log.takeLast(2).forEach {
+                Text(it, style = MaterialTheme.typography.bodySmall)
+            }
+        }
+
+        abandoned?.let { PatienceLeftDialog(it, onExit, controller::dismissAbandoned) }
+        if (confirmingEnd) {
+            PatienceEndDialog("The pyramid is left as it stands.", onExit) { confirmingEnd = false }
+        }
+    }
+}
+
+@Composable
+private fun PyramidView(
+    state: PyramidState,
+    held: PyramidSpot?,
+    kings: Set<PyramidSpot>,
+    partners: Set<PyramidSpot>,
+    pairable: Set<PyramidSpot>,
+    onTap: (PyramidSpot) -> Unit,
+) {
+    Box(
+        modifier = Modifier
+            .fillMaxWidth()
+            .height(PYRAMID_CARD_HEIGHT + ROW_STEP * (ROWS - 1)),
+    ) {
+        // Each row is half a card narrower on each side than the one below, so
+        // every card sits in the notch between the two under it.
+        for (row in 0 until ROWS) {
+            val cardsInRow = row + 1
+            for (column in 0 until cardsInRow) {
+                val index = rowStart(row) + column
+                val card = state.pyramid[index] ?: continue
+                val spot = PyramidSpot(PyramidZone.PYRAMID, index)
+                val playable = pairable.contains(spot) || kings.contains(spot)
+                Box(
+                    modifier = Modifier.offset(
+                        // Centred on the widest row, which is seven wide.
+                        x = PYRAMID_CARD * (ROWS - cardsInRow) / 2f + PYRAMID_CARD * column,
+                        y = ROW_STEP * row,
+                    ),
+                ) {
+                    TableSlot(
+                        highlighted = held == spot || partners.contains(spot),
+                        width = PYRAMID_CARD,
+                        onClick = { if (playable) onTap(spot) },
+                    ) {
+                        PlayingCardView(
+                            card = card,
+                            width = PYRAMID_CARD,
+                            enabled = playable,
+                            caption = valueOf(card).toString(),
+                        )
+                    }
+                }
+            }
+        }
+    }
+}

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

@@ -0,0 +1,191 @@
+package org.prolibertate.games.ui.game
+
+import androidx.compose.foundation.horizontalScroll
+import androidx.compose.foundation.layout.Arrangement
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.Row
+import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.height
+import androidx.compose.foundation.layout.offset
+import androidx.compose.foundation.layout.width
+import androidx.compose.foundation.rememberScrollState
+import androidx.compose.foundation.verticalScroll
+import androidx.compose.material3.Button
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.Text
+import androidx.compose.material3.TextButton
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.collectAsState
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.runtime.setValue
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.text.font.FontWeight
+import androidx.compose.ui.unit.dp
+import org.prolibertate.games.game.spider.DealRow
+import org.prolibertate.games.game.spider.MoveRun
+import org.prolibertate.games.game.spider.RUNS_TO_WIN
+import org.prolibertate.games.game.spider.SpiderMove
+import org.prolibertate.games.game.spider.SpiderState
+import org.prolibertate.games.net.MatchController
+import org.prolibertate.games.ui.ScreenScaffold
+import org.prolibertate.games.ui.common.CardBackView
+import org.prolibertate.games.ui.common.PlayingCardView
+
+private const val TITLE = "Spider"
+
+/**
+ * The Spider table.
+ *
+ * Ten columns of a hundred and four cards, so it scrolls sideways and the cards
+ * are the same third-overlapped stacks as everywhere else. What is worth showing
+ * above them is the two numbers that decide the game: how many runs have gone
+ * away, and how many rows are still in the stock waiting to bury everything.
+ */
+@Composable
+fun SpiderScreen(
+    controller: MatchController<SpiderState, SpiderMove>,
+    onRestart: () -> Unit,
+    onExit: () -> Unit,
+) {
+    val state by controller.state.collectAsState()
+    val legal by controller.legalMoves.collectAsState()
+    val abandoned by controller.abandoned.collectAsState()
+
+    var held by remember { mutableStateOf<Pair<Int, Int>?>(null) }
+    var confirmingEnd by remember { mutableStateOf(false) }
+
+    val endGameAction: @Composable () -> Unit = {
+        TextButton(onClick = { confirmingEnd = true }) { Text("End game") }
+    }
+
+    val current = state
+    if (current == null) {
+        ScreenScaffold(title = TITLE, onBack = onExit, actions = endGameAction) { modifier ->
+            Box(modifier, contentAlignment = Alignment.Center) { Text("Dealing…") }
+            abandoned?.let { PatienceLeftDialog(it, onExit, controller::dismissAbandoned) }
+            if (confirmingEnd) {
+                PatienceEndDialog("The deal is left as it stands.", onExit) { confirmingEnd = false }
+            }
+        }
+        return
+    }
+
+    val runs = legal.filterIsInstance<MoveRun>()
+    val canDeal = legal.contains(DealRow)
+    val finished = legal.isEmpty()
+    val targets = held?.let { (from, count) ->
+        runs.filter { it.from == from && it.count == count }.map { it.to }.toSet()
+    }.orEmpty()
+    val sources = runs.map { it.from to it.count }.toSet()
+
+    fun take(column: Int, count: Int) {
+        val inHand = held
+        held = when {
+            inHand != null && targets.contains(column) -> {
+                controller.submit(MoveRun(inHand.first, column, inHand.second))
+                null
+            }
+
+            inHand?.first == column && inHand.second == count -> null
+            sources.contains(column to count) -> column to count
+            else -> null
+        }
+    }
+
+    ScreenScaffold(title = TITLE, onBack = onExit, actions = endGameAction) { modifier ->
+        Column(
+            modifier = modifier.verticalScroll(rememberScrollState()),
+            verticalArrangement = Arrangement.spacedBy(10.dp),
+        ) {
+            Text(
+                text = when {
+                    current.isWon -> "All eight runs, in ${current.moves} moves."
+                    finished -> "Blocked — nothing left to try."
+                    held != null -> "Tap the column it goes to."
+                    else -> "${current.completed} of $RUNS_TO_WIN runs away."
+                },
+                fontWeight = FontWeight.Bold,
+            )
+
+            Row(
+                horizontalArrangement = Arrangement.spacedBy(8.dp),
+                verticalAlignment = Alignment.CenterVertically,
+            ) {
+                TableSlot(
+                    highlighted = false,
+                    onClick = { if (canDeal) controller.submit(DealRow) },
+                ) {
+                    if (current.stock.isNotEmpty()) {
+                        CardBackView(width = TABLE_CARD_WIDTH)
+                    } else {
+                        EmptySpace()
+                    }
+                }
+                Text(
+                    text = "${current.stock.size / 10} rows left" +
+                        if (!canDeal && current.stock.isNotEmpty()) " — fill every column first" else "",
+                    style = MaterialTheme.typography.bodySmall,
+                )
+            }
+
+            Row(
+                modifier = Modifier.fillMaxWidth().horizontalScroll(rememberScrollState()),
+                horizontalArrangement = Arrangement.spacedBy(4.dp),
+                verticalAlignment = Alignment.Top,
+            ) {
+                current.tableau.forEachIndexed { index, pile ->
+                    val total = pile.faceDown.size + pile.faceUp.size
+                    if (total == 0) {
+                        TableSlot(
+                            highlighted = targets.contains(index),
+                            onClick = { take(index, 1) },
+                        ) { EmptySpace() }
+                    } else {
+                        Box(
+                            modifier = Modifier
+                                .width(TABLE_CARD_WIDTH)
+                                .height(TABLE_CARD_HEIGHT + TABLE_STACK_STEP * (total - 1)),
+                        ) {
+                            pile.faceDown.forEachIndexed { depth, _ ->
+                                CardBackView(
+                                    width = TABLE_CARD_WIDTH,
+                                    modifier = Modifier.offset(y = TABLE_STACK_STEP * depth),
+                                )
+                            }
+                            pile.faceUp.forEachIndexed { depth, card ->
+                                val count = pile.faceUp.size - depth
+                                val row = pile.faceDown.size + depth
+                                TableSlot(
+                                    modifier = Modifier.offset(y = TABLE_STACK_STEP * row),
+                                    highlighted = held == (index to count) ||
+                                        (depth == pile.faceUp.lastIndex && targets.contains(index)),
+                                    onClick = { take(index, count) },
+                                ) { PlayingCardView(card = card, width = TABLE_CARD_WIDTH) }
+                            }
+                        }
+                    }
+                }
+            }
+
+            if (finished) {
+                Row(horizontalArrangement = Arrangement.spacedBy(8.dp)) {
+                    Button(onClick = onRestart) { Text("Deal again") }
+                    TextButton(onClick = onExit) { Text("Leave") }
+                }
+            }
+
+            current.log.takeLast(2).forEach {
+                Text(it, style = MaterialTheme.typography.bodySmall)
+            }
+        }
+
+        abandoned?.let { PatienceLeftDialog(it, onExit, controller::dismissAbandoned) }
+        if (confirmingEnd) {
+            PatienceEndDialog("The deal is left as it stands.", onExit) { confirmingEnd = false }
+        }
+    }
+}

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

@@ -75,6 +75,9 @@ class CatalogTest {
                 GameCatalog.PEG_SOLITAIRE,
                 GameCatalog.YAHTZEE,
                 GameCatalog.KLONDIKE,
+                GameCatalog.FREECELL,
+                GameCatalog.SPIDER,
+                GameCatalog.PYRAMID,
                 GameCatalog.WIZARD,
                 GameCatalog.CHESS,
                 GameCatalog.TAYU,

app/src/test/java/org/prolibertate/games/game/solitaire/SolitaireRulesTest.kt

@@ -0,0 +1,368 @@
+package org.prolibertate.games.game.solitaire
+
+import kotlinx.serialization.encodeToString
+import kotlinx.serialization.json.Json
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertFalse
+import org.junit.Assert.assertNull
+import org.junit.Assert.assertTrue
+import org.junit.Test
+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.PlayerKind
+import org.prolibertate.games.game.engine.PlayerSlot
+import org.prolibertate.games.game.engine.TableConfig
+import org.prolibertate.games.game.freecell.COLUMNS as FREECELL_COLUMNS
+import org.prolibertate.games.game.freecell.FreeCellOptions
+import org.prolibertate.games.game.freecell.FreeCellRules
+import org.prolibertate.games.game.freecell.MoveTo
+import org.prolibertate.games.game.freecell.Place
+import org.prolibertate.games.game.freecell.maxRunLength
+import org.prolibertate.games.game.pyramid.PYRAMID_SIZE
+import org.prolibertate.games.game.pyramid.PyramidOptions
+import org.prolibertate.games.game.pyramid.PyramidRules
+import org.prolibertate.games.game.pyramid.PyramidZone
+import org.prolibertate.games.game.pyramid.TARGET
+import org.prolibertate.games.game.pyramid.coveredBy
+import org.prolibertate.games.game.pyramid.isExposed
+import org.prolibertate.games.game.pyramid.rowOf
+import org.prolibertate.games.game.pyramid.valueOf
+import org.prolibertate.games.game.spider.COLUMNS as SPIDER_COLUMNS
+import org.prolibertate.games.game.spider.DealRow
+import org.prolibertate.games.game.spider.RUN_LENGTH
+import org.prolibertate.games.game.spider.SpiderOptions
+import org.prolibertate.games.game.spider.SpiderRules
+import org.prolibertate.games.game.spider.isCompleteRun
+import org.prolibertate.games.game.spider.landsOn
+import org.prolibertate.games.game.spider.sameSuitRun
+import org.prolibertate.games.game.spider.spiderDeck
+
+/**
+ * The three patiences added together, tested together.
+ *
+ * They share the ace-low ordering and little else, so what is worth pinning is
+ * each one's own shape: how many cards it deals, what it will let travel, and
+ * what counts as finished.
+ */
+class SolitaireRulesTest {
+
+    private val json = Json { encodeDefaults = true }
+
+    private fun soloConfig(gameId: String, optionsJson: String, seed: Long = 3L) = TableConfig(
+        gameId = gameId,
+        seats = listOf(PlayerSlot(seat = 0, name = "P0", kind = PlayerKind.HUMAN_LOCAL, team = 0)),
+        optionsJson = optionsJson,
+        seed = seed,
+    )
+
+    private fun c(rank: Rank, suit: Suit) = Card(rank, suit)
+
+    // ---- shared ------------------------------------------------------------
+
+    @Test
+    fun `the ace is low for all of them`() {
+        assertEquals(1, Rank.ACE.patienceOrder)
+        assertEquals(11, Rank.JACK.patienceOrder)
+        assertEquals(13, Rank.KING.patienceOrder)
+        assertTrue(buildsDownAlternating(c(Rank.ACE, Suit.HEARTS), c(Rank.TWO, Suit.SPADES)))
+        assertTrue(buildsDownInSuit(c(Rank.ACE, Suit.SPADES), c(Rank.TWO, Suit.SPADES)))
+        assertFalse(buildsDownInSuit(c(Rank.ACE, Suit.HEARTS), c(Rank.TWO, Suit.SPADES)))
+    }
+
+    // ---- FreeCell ----------------------------------------------------------
+
+    @Test
+    fun `FreeCell deals the whole pack face up`() {
+        val state = FreeCellRules.initialState(
+            soloConfig("freecell", json.encodeToString(FreeCellOptions())),
+        )
+        assertEquals(FREECELL_COLUMNS, state.tableau.size)
+        // Fifty-two into eight is four sevens and four sixes.
+        assertEquals(listOf(7, 7, 7, 7, 6, 6, 6, 6), state.tableau.map { it.size })
+        val all = state.tableau.flatten()
+        assertEquals(52, all.size)
+        assertEquals(52, all.distinct().size)
+        assertEquals(4, state.freeCellCount)
+        assertEquals(0, state.emptyColumns)
+    }
+
+    @Test
+    fun `how much can travel depends on cells and spaces`() {
+        // One card per free cell plus the card itself, doubled for each empty
+        // column that can be borrowed as a staging pile.
+        assertEquals(5, maxRunLength(freeCells = 4, emptyColumns = 0, intoEmptyColumn = false))
+        assertEquals(10, maxRunLength(freeCells = 4, emptyColumns = 1, intoEmptyColumn = false))
+        assertEquals(20, maxRunLength(freeCells = 4, emptyColumns = 2, intoEmptyColumn = false))
+        // Moving into an empty column cannot also stage through it.
+        assertEquals(5, maxRunLength(freeCells = 4, emptyColumns = 1, intoEmptyColumn = true))
+        assertEquals(1, maxRunLength(freeCells = 0, emptyColumns = 0, intoEmptyColumn = false))
+    }
+
+    @Test
+    fun `FreeCell refuses a table for more than one`() {
+        val two = TableConfig(
+            gameId = "freecell",
+            seats = (0..1).map { PlayerSlot(seat = it, name = "P$it", kind = PlayerKind.AI, team = it) },
+            optionsJson = json.encodeToString(FreeCellOptions()),
+            seed = 1L,
+        )
+        assertThrows { FreeCellRules.initialState(two) }
+    }
+
+    @Test
+    fun `FreeCell keeps every card wherever it is put`() {
+        var state = FreeCellRules.initialState(
+            soloConfig("freecell", json.encodeToString(FreeCellOptions())),
+        )
+        val ai = FirstLegalAi<org.prolibertate.games.game.freecell.FreeCellState,
+            org.prolibertate.games.game.freecell.FreeCellMove>()
+        var guard = 120
+        while (!FreeCellRules.isFinished(state) && guard-- > 0) {
+            val legal = FreeCellRules.legalMoves(state, 0)
+            state = FreeCellRules.applyMove(state, 0, ai.chooseMove(state, 0, legal))
+            val all = state.tableau.flatten() + state.foundations.flatten() + state.cells.filterNotNull()
+            assertEquals("no card lost or copied", 52, all.size)
+            assertEquals(52, all.distinct().size)
+        }
+    }
+
+    @Test
+    fun `parking a card takes it off the column and into the cell`() {
+        val state = FreeCellRules.initialState(
+            soloConfig("freecell", json.encodeToString(FreeCellOptions())),
+        )
+        val toCell = FreeCellRules.legalMoves(state, 0)
+            .filterIsInstance<MoveTo>()
+            .first { it.to.kind == org.prolibertate.games.game.freecell.CellKind.CELL }
+        val column = toCell.from.index
+        val card = state.tableau[column].last()
+
+        val parked = FreeCellRules.applyMove(state, 0, toCell)
+        assertEquals(3, parked.freeCellCount)
+        assertEquals(card, parked.cells[toCell.to.index])
+        assertEquals(state.tableau[column].size - 1, parked.tableau[column].size)
+        // Deliberately not asserting the card can come back out. A parked card
+        // that nothing will take is stranded, and that is the whole danger of
+        // the cells rather than a fault in them.
+    }
+
+    @Test
+    fun `an ace in a cell can always go home`() {
+        val base = FreeCellRules.initialState(
+            soloConfig("freecell", json.encodeToString(FreeCellOptions())),
+        )
+        val ace = c(Rank.ACE, Suit.SPADES)
+        val held = base.copy(cells = listOf(ace, null, null, null))
+        assertTrue(
+            "an ace is the one card a cell can never strand",
+            FreeCellRules.legalMoves(held, 0).contains(
+                MoveTo(Place.cell(0), Place.foundation(Suit.SPADES.ordinal), 1),
+            ),
+        )
+    }
+
+    // ---- Spider ------------------------------------------------------------
+
+    @Test
+    fun `a Spider pack is always a hundred and four`() {
+        listOf(1, 2, 4).forEach { suits ->
+            val deck = spiderDeck(suits)
+            assertEquals("$suits suits", 104, deck.size)
+            assertEquals("$suits suits", suits, deck.map { it.suit }.distinct().size)
+            // Eight of every rank, however the suits were shared out.
+            assertEquals(8, deck.count { it.rank == Rank.KING })
+        }
+    }
+
+    @Test
+    fun `Spider deals fifty-four and keeps fifty back`() {
+        val state = SpiderRules.initialState(
+            soloConfig("spider", json.encodeToString(SpiderOptions())),
+        )
+        assertEquals(SPIDER_COLUMNS, state.tableau.size)
+        assertEquals(listOf(6, 6, 6, 6, 5, 5, 5, 5, 5, 5), state.tableau.map { it.faceDown.size + it.faceUp.size })
+        state.tableau.forEach { assertEquals("only the last is turned up", 1, it.faceUp.size) }
+        assertEquals(50, state.stock.size)
+        assertEquals(0, state.completed)
+    }
+
+    @Test
+    fun `only a same-suit run travels, but anything lands on a higher card`() {
+        val spades = listOf(c(Rank.TEN, Suit.SPADES), c(Rank.NINE, Suit.SPADES))
+        val mixed = listOf(c(Rank.TEN, Suit.SPADES), c(Rank.NINE, Suit.HEARTS))
+        assertTrue(sameSuitRun(spades))
+        assertFalse("a mixed run cannot travel as one", sameSuitRun(mixed))
+        // Landing is looser than travelling: any suit, one rank higher.
+        assertTrue(landsOn(c(Rank.NINE, Suit.HEARTS), c(Rank.TEN, Suit.SPADES)))
+        assertFalse(landsOn(c(Rank.NINE, Suit.HEARTS), c(Rank.JACK, Suit.SPADES)))
+    }
+
+    @Test
+    fun `a complete run is king down to ace in one suit`() {
+        val run = Rank.standard.sortedByDescending { it.patienceOrder }.map { c(it, Suit.SPADES) }
+        assertEquals(RUN_LENGTH, run.size)
+        assertTrue(isCompleteRun(run))
+        // One card of the wrong suit and it is not going anywhere.
+        val broken = run.toMutableList().also { it[5] = c(it[5].rank, Suit.HEARTS) }
+        assertFalse(isCompleteRun(broken))
+        assertFalse(isCompleteRun(run.drop(1)))
+    }
+
+    @Test
+    fun `a row cannot be dealt onto an empty column`() {
+        val state = SpiderRules.initialState(
+            soloConfig("spider", json.encodeToString(SpiderOptions())),
+        )
+        assertTrue(state.canDeal)
+        assertTrue(SpiderRules.legalMoves(state, 0).contains(DealRow))
+
+        val emptied = state.copy(
+            tableau = state.tableau.toMutableList().also {
+                it[0] = org.prolibertate.games.game.spider.SpiderPile()
+            },
+        )
+        assertFalse(emptied.canDeal)
+        assertFalse(SpiderRules.legalMoves(emptied, 0).contains(DealRow))
+    }
+
+    @Test
+    fun `dealing a row puts one card on every column`() {
+        val state = SpiderRules.initialState(
+            soloConfig("spider", json.encodeToString(SpiderOptions())),
+        )
+        val before = state.tableau.map { it.faceUp.size }
+        val dealt = SpiderRules.applyMove(state, 0, DealRow)
+        assertEquals(40, dealt.stock.size)
+        dealt.tableau.forEachIndexed { index, pile ->
+            assertEquals(before[index] + 1, pile.faceUp.size)
+        }
+    }
+
+    // ---- Pyramid -----------------------------------------------------------
+
+    @Test
+    fun `the pyramid is twenty-eight cards in seven rows`() {
+        assertEquals(28, PYRAMID_SIZE)
+        assertEquals(0, rowOf(0))
+        assertEquals(1, rowOf(1))
+        assertEquals(1, rowOf(2))
+        assertEquals(2, rowOf(3))
+        assertEquals(6, rowOf(27))
+
+        val state = PyramidRules.initialState(
+            soloConfig("pyramid", json.encodeToString(PyramidOptions())),
+        )
+        assertEquals(PYRAMID_SIZE, state.pyramid.size)
+        assertEquals(24, state.stock.size)
+        assertTrue(state.pyramid.all { it != null })
+    }
+
+    @Test
+    fun `a card is buried until both the cards on it are gone`() {
+        // The apex rests on the two cards of the second row.
+        assertEquals(listOf(1, 2), coveredBy(0))
+        // The bottom row rests on nothing.
+        assertTrue(coveredBy(27).isEmpty())
+
+        val pyramid = MutableList<Card?>(PYRAMID_SIZE) { c(Rank.FIVE, Suit.SPADES) }
+        assertFalse("the apex starts buried", isExposed(pyramid, 0))
+        pyramid[1] = null
+        assertFalse("one of the two is not enough", isExposed(pyramid, 0))
+        pyramid[2] = null
+        assertTrue(isExposed(pyramid, 0))
+        // A place already taken is not exposed, it is gone.
+        pyramid[0] = null
+        assertFalse(isExposed(pyramid, 0))
+    }
+
+    @Test
+    fun `pairs make thirteen, and a king makes it alone`() {
+        assertEquals(1, valueOf(c(Rank.ACE, Suit.SPADES)))
+        assertEquals(11, valueOf(c(Rank.JACK, Suit.SPADES)))
+        assertEquals(TARGET, valueOf(c(Rank.KING, Suit.SPADES)))
+        assertEquals(TARGET, valueOf(c(Rank.ACE, Suit.SPADES)) + valueOf(c(Rank.QUEEN, Suit.HEARTS)))
+        assertEquals(TARGET, valueOf(c(Rank.SIX, Suit.CLUBS)) + valueOf(c(Rank.SEVEN, Suit.DIAMONDS)))
+    }
+
+    @Test
+    fun `only the bottom row is in play at the start`() {
+        val state = PyramidRules.initialState(
+            soloConfig("pyramid", json.encodeToString(PyramidOptions())),
+        )
+        val reachable = PyramidRules.available(state)
+        val fromPyramid = reachable.filter { it.first.zone == PyramidZone.PYRAMID }
+        assertEquals("the seven of the bottom row", 7, fromPyramid.size)
+        assertTrue(fromPyramid.all { rowOf(it.first.index) == 6 })
+        // Nothing has been turned yet, so the waste offers nothing.
+        assertTrue(reachable.none { it.first.zone == PyramidZone.WASTE })
+    }
+
+    @Test
+    fun `drawing turns a card and the waste can be turned back`() {
+        var state = PyramidRules.initialState(
+            soloConfig("pyramid", json.encodeToString(PyramidOptions(redeals = 1))),
+        )
+        val stock = state.stock.size
+        state = PyramidRules.applyMove(state, 0, org.prolibertate.games.game.pyramid.DrawCard)
+        assertEquals(stock - 1, state.stock.size)
+        assertEquals(1, state.waste.size)
+
+        var guard = 40
+        while (state.stock.isNotEmpty() && guard-- > 0) {
+            state = PyramidRules.applyMove(state, 0, org.prolibertate.games.game.pyramid.DrawCard)
+        }
+        assertTrue(state.canRedeal)
+        val turned = PyramidRules.applyMove(state, 0, org.prolibertate.games.game.pyramid.RecycleWaste)
+        assertTrue(turned.waste.isEmpty())
+        assertEquals(1, turned.redealsUsed)
+        assertFalse("only the one redeal was allowed", turned.canRedeal)
+    }
+
+    @Test
+    fun `a cleared pyramid is won`() {
+        val state = PyramidRules.initialState(
+            soloConfig("pyramid", json.encodeToString(PyramidOptions())),
+        )
+        val cleared = state.copy(pyramid = List(PYRAMID_SIZE) { null })
+        assertTrue(cleared.isWon)
+        assertTrue(PyramidRules.isFinished(cleared))
+        assertNull(PyramidRules.currentSeat(cleared))
+        assertTrue(PyramidRules.summary(cleared).contains("Cleared"))
+    }
+
+    // ---- codecs ------------------------------------------------------------
+
+    @Test
+    fun `each of them survives a round trip`() {
+        val freecell = FreeCellRules.initialState(
+            soloConfig("freecell", json.encodeToString(FreeCellOptions())),
+        )
+        assertEquals(freecell, FreeCellRules.decodeState(FreeCellRules.encodeState(freecell)))
+
+        val spider = SpiderRules.initialState(
+            soloConfig("spider", json.encodeToString(SpiderOptions(suits = 4))),
+        )
+        assertEquals(spider, SpiderRules.decodeState(SpiderRules.encodeState(spider)))
+        assertEquals(DealRow, SpiderRules.decodeMove(SpiderRules.encodeMove(DealRow)))
+
+        val pyramid = PyramidRules.initialState(
+            soloConfig("pyramid", json.encodeToString(PyramidOptions())),
+        )
+        assertEquals(pyramid, PyramidRules.decodeState(PyramidRules.encodeState(pyramid)))
+        val king = org.prolibertate.games.game.pyramid.TakeKing(PyramidSpotAt(3))
+        assertEquals(king, PyramidRules.decodeMove(PyramidRules.encodeMove(king)))
+    }
+
+    private fun PyramidSpotAt(index: Int) =
+        org.prolibertate.games.game.pyramid.PyramidSpot(PyramidZone.PYRAMID, index)
+
+    private fun assertThrows(block: () -> Unit) {
+        try {
+            block()
+            throw AssertionError("expected the rules to reject that")
+        } catch (expected: IllegalArgumentException) {
+            // Rejected, which is the point.
+        }
+    }
+}