Add support for up to 6 players.

internal/game/sim.go

@@ -1,15 +1,15 @@
 package game
 
-// SimulateBattle resolves a hypothetical two-player battle between the given
-// arranged decks (top of deck first) and returns the result. It runs on a
-// scratch game, so it never touches real state — callers (notably the AI
-// player) can roll out as many what-if battles as they like. Dice rolls are
-// random unless rollDie is non-nil.
-func SimulateBattle(round, prioritySeat int, deckA, deckB []Card, rollDie func() int) *BattleResult {
+// SimulateBattle resolves a hypothetical battle between the given arranged
+// decks (top of deck first) and returns the result. deckA sits at seat 0 and
+// deckB at seat 1; firstSeat (0 or 1) is the one holding priority. It runs on
+// a scratch game and awards nothing, so it never touches real state — callers
+// (notably the AI player) can roll out as many what-if battles as they like.
+// Dice rolls are random unless rollDie is non-nil.
+func SimulateBattle(round, firstSeat int, deckA, deckB []Card, rollDie func() int) *BattleResult {
 	g := &Game{
-		Round:        round,
-		PrioritySeat: prioritySeat,
-		RollDie:      rollDie,
+		Round:   round,
+		RollDie: rollDie,
 		// Cards minted during the simulation (apples, bees) get IDs far away
 		// from real ones, purely to avoid confusion when reading results.
 		NextCardID: 1_000_000,
@@ -18,22 +18,24 @@ func SimulateBattle(round, prioritySeat int, deckA, deckB []Card, rollDie func()
 			{Name: "B", Seat: 1, Deck: append([]Card(nil), deckB...)},
 		},
 	}
-	g.startBattle()
-	return g.Battle
+	if firstSeat == 1 {
+		return g.runBattle(1, 0)
+	}
+	return g.runBattle(0, 1)
 }
 
 // TierContents returns the full printed contents of a tier's shop deck for the
 // default pack. Cards carry placeholder IDs; they are reference data, not live
 // instances.
 func TierContents(tier int) []Card {
-	return TierContentsForPack(DefaultPack, tier)
+	return TierContentsForPacks([]string{DefaultPack}, tier)
 }
 
-// TierContentsForPack returns a pack's printed tier contents — public
-// information from the box. Used by the AI, which decides from a View that
-// names its pack.
-func TierContentsForPack(pack string, tier int) []Card {
-	scratch := &Game{Pack: pack}
+// TierContentsForPacks returns the printed tier contents of a pack selection,
+// combined the way the shop decks combine them — public information from the
+// boxes. Used by the AI, which decides from a View that names its packs.
+func TierContentsForPacks(packs []string, tier int) []Card {
+	scratch := &Game{Packs: packs}
 	scratch.buildShopDecks()
 	if tier < 1 || tier > len(scratch.ShopDecks) {
 		return nil