Make the AI a little smarter.

internal/game/battle.go

@@ -160,6 +160,11 @@ type BattleResult struct {
 	Events     []BattleEvent `json:"events"`
 	WinnerSeat int           `json:"winnerSeat"` // -1 = draw
 	Trophies   int           `json:"trophies"`   // awarded to the winner
+	// Survivors is each seat's remaining force at battle end: pets still in
+	// play plus any never reached in the stack. The loser is 0. It measures how
+	// decisive the result was — the margin the AI uses to prefer a lineup that
+	// fights harder, even in a battle it can't win.
+	Survivors []int `json:"survivors,omitempty"`
 }
 
 // setAsideRocks is a fainted pet's pending rock payout.
@@ -1312,5 +1317,21 @@ func (g *Game) runBattle() *BattleResult {
 			res.Trophies = 2
 		}
 	}
+
+	// Record each side's leftover force: a live pet in play plus any pets never
+	// reached in the stack. The loser lands on 0.
+	res.Survivors = make([]int, n)
+	for seat, s := range sides {
+		cnt := 0
+		if s.unit != nil && s.unit.Alive() {
+			cnt++
+		}
+		for _, c := range s.stack {
+			if c.IsPet() {
+				cnt++
+			}
+		}
+		res.Survivors[seat] = cnt
+	}
 	return res
 }

internal/game/golden45_test.go

@@ -171,6 +171,11 @@ func TestSelfFaintWithReserveStillWins(t *testing.T) {
 	if res.WinnerSeat != 0 {
 		t.Fatalf("seat 0 should win with a reserve pet vs an all-food deck, got winner %d", res.WinnerSeat)
 	}
+	// The survivor margin reflects the leftover force: seat 0's unrevealed
+	// Reserve still counts, seat 1 has nothing.
+	if got := res.Survivors; len(got) != 2 || got[0] < 1 || got[1] != 0 {
+		t.Fatalf("survivors should be [>=1, 0], got %v", got)
+	}
 }
 
 // Poison Dart Frog, once set aside, throws rocks each time a Bee is played.