Initial pass at unicorn pack.

internal/ai/ai.go

@@ -35,12 +35,12 @@ import (
 
 // Action is one move the bot wants to make, mirroring the client protocol.
 type Action struct {
-	Type   string   // buy | buyAvocado | sell | trade | tradeChoose | pass | arrange | ready | revealChoose
+	Type   string   // buy | buyAvocado | sell | trade | tradeChoose | pass | arrange | ready | revealChoose | sacrificeChoose
 	Row    int      // buy / buyAvocado
 	Cards  []string // sell / trade
 	Pick   int      // tradeChoose
 	Order  []string // arrange
-	CardID string   // revealChoose (Cockatoo): the pet to reveal
+	CardID string   // revealChoose (Cockatoo) / sacrificeChoose (Water of Youth): the pet
 }
 
 // Bot is a computer player at a fixed difficulty level.
@@ -62,6 +62,12 @@ func (b *Bot) Act(v *game.View, mem *Memory) *Action {
 	me := &v.Players[v.YouSeat]
 	switch v.Phase {
 	case game.PhaseShop:
+		if v.PendingSacrifice != nil {
+			if v.PendingSacrifice.PlayerID == me.ID {
+				return b.decideSacrifice(v)
+			}
+			return nil
+		}
 		if v.PendingReveal != nil {
 			if v.PendingReveal.PlayerID == me.ID {
 				return b.decideReveal(v)
@@ -107,6 +113,26 @@ func (b *Bot) decideReveal(v *game.View) *Action {
 	return &Action{Type: "revealChoose", CardID: best}
 }
 
+// decideSacrifice resolves Water of Youth (Unicorn pack): give up the
+// lowest-value eligible pet to upgrade into a next-tier card.
+func (b *Bot) decideSacrifice(v *game.View) *Action {
+	me := &v.Players[v.YouSeat]
+	worst, worstVal := "", math.Inf(1)
+	for _, id := range v.PendingSacrifice.Options {
+		for _, c := range me.Deck {
+			if c.ID == id {
+				if val := keepValue(c); val < worstVal {
+					worst, worstVal = id, val
+				}
+			}
+		}
+	}
+	if worst == "" && len(v.PendingSacrifice.Options) > 0 {
+		worst = v.PendingSacrifice.Options[0]
+	}
+	return &Action{Type: "sacrificeChoose", CardID: worst}
+}
+
 // Pending reports whether the seat owes the game an action right now — the
 // server uses it to decide when to schedule a bot move.
 func Pending(v *game.View) bool {
@@ -116,6 +142,9 @@ func Pending(v *game.View) bool {
 	me := &v.Players[v.YouSeat]
 	switch v.Phase {
 	case game.PhaseShop:
+		if v.PendingSacrifice != nil {
+			return v.PendingSacrifice.PlayerID == me.ID
+		}
 		if v.PendingReveal != nil {
 			return v.PendingReveal.PlayerID == me.ID
 		}