fix: preserve gameplay data and correct duel evaluation

- Preserve snake customizations across database migrations and merges.
- Lazily load optional storage backends for SQLite maintenance scripts.
- Match Apex territory and nearest-food tie-breaking semantics.
- Resolve duel occupancy after simultaneous movement and food growth.
- Recompute simulated head-to-head danger after body growth.
- Add regression coverage and declare the aiofiles dependency.

snakes/PrismBattleSnake_GPT_5_6_Sol.py

@@ -1,4 +1,4 @@
-"""PrismBattleSnake_GPT_5_6_Sol v1.0.0
+"""PrismBattleSnake_GPT_5_6_Sol v1.0.1
 
 Built on ApexBattleSnake v1.0.0.  All strategic logic is inherited.
 Performance improvement: all spatial primitives (flood fill, territory,
@@ -41,7 +41,7 @@ _DIR_DELTAS = ((0, 1), (0, -1), (-1, 0), (1, 0))
 _DIR_NAMES = ("up", "down", "left", "right")
 
 class PrismBattleSnake_GPT_5_6_Sol(ApexBattleSnake):
-  VERSION = "1.0.0"
+  VERSION = "1.0.1"
 
   def __init__(self) -> None:
     super().__init__()
@@ -83,6 +83,11 @@ class PrismBattleSnake_GPT_5_6_Sol(ApexBattleSnake):
     my_snake = game_data.get_my_snake()
     my_len = my_snake.get("length", len(my_snake["body"]))
     food_set = {(f["x"], f["y"]) for f in game_data.get_food()}
+    all_occupied = {
+      (seg["x"], seg["y"])
+      for snake in [my_snake, *other_snakes]
+      for seg in snake["body"]
+    }
     game_type = game_data.get_type()
     is_constrictor = game_type == "constrictor"
     w = bb.width
@@ -100,7 +105,7 @@ class PrismBattleSnake_GPT_5_6_Sol(ApexBattleSnake):
       if not is_constrictor and len(body) >= 2:
         tail_stacked = (body[-1]["x"] == body[-2]["x"] and body[-1]["y"] == body[-2]["y"])
         if not tail_stacked:
-          can_grow = self._enemy_can_grow_this_turn(snake, food_set)
+          can_grow = self._enemy_can_grow_this_turn(snake, food_set, all_occupied)
           if not can_grow:
             enemy_tail_bits |= 1 << (body[-1]["y"] * w + body[-1]["x"])
 
@@ -354,17 +359,25 @@ class PrismBattleSnake_GPT_5_6_Sol(ApexBattleSnake):
       return -5000.0
 
     # ── Safe next options (enemy-attack aware) ────────────────────────
-    # Remove tiles where an enemy of >= our length could head-to-head.
-    # The danger bitboard was precomputed; filter out tiles blocked by
-    # current body (enemy can't step there either).
-    danger_here = self._enemy_attack_danger & ~blocked_bits
+    # Rebuild danger for the simulated length. The root-turn danger mask is
+    # stale after eating and includes enemy moves blocked in this future body.
+    danger_here = 0
+    for enemy in other_snakes:
+      enemy_len = enemy.get("length", len(enemy["body"]))
+      if enemy_len < body_len:
+        continue
+      enemy_head = enemy["head"]
+      enemy_idx = enemy_head["y"] * w + enemy_head["x"]
+      danger_here |= bb._neighbor_masks[enemy_idx]
+    danger_here &= ~blocked_bits
     safe_nb = nb_free & ~danger_here
     en_safe = safe_nb.bit_count()
 
     if en_safe == 0:
       return -4000.0
 
-    sc = reachable * 1.9 + liberties * 14.0 + liberties * 11.0 + en_safe * 26.0
+    next_opts = liberties
+    sc = reachable * 1.9 + liberties * 14.0 + next_opts * 11.0 + en_safe * 26.0
     if en_safe == 1:
       sc -= 420.0
     return sc