The stone pierces walls for creations too (rules rev 3)

VISIONSTONE only ever lit the attack path: casterLos knew it, but
every sight check routed through gameLos — creations like THORNBUSH,
dispels, CREATE DOOR, STONE TO WATER — refused "no line of sight"
through the bearer's one wall. gameLos now honors the stone whenever
the viewer bears it, at every revision: widening what a cast may
target never changes how a recorded command replays, so games already
in flight get the fix at once. Only the ambush's mid-move eye is
frozen per game (rev 3) — springing lands in the ledger's flow, and
stored games must replay their blindness. All 18 production ledgers
verified; 272 engine tests.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_015RCWSTnb1KYTPyL4GmhGnF

packages/engine/src/game.ts

@@ -226,7 +226,7 @@ export interface CastParams {
 }
 
 /** The revision new games are dealt under; GameConfig.deckRev pins it per game. */
-export const CURRENT_RULES_REV = 2;
+export const CURRENT_RULES_REV = 3;
 
 export interface GameConfig {
   playerIds: PlayerId[];
@@ -242,6 +242,9 @@ export interface GameConfig {
    * Rev 2: a wizard beside a door they can open (lock removed, door
    * unlocked this turn, or PICK LOCK / MASTER KEY in hand) sees through
    * the doorway; the hallway behind them still cannot.
+   * Rev 3: VISIONSTONE pierces its one wall for every sight the game
+   * asks of its bearer — creations and utility spells included — not
+   * only direct attacks.
    */
   deckRev?: number;
 }
@@ -378,8 +381,37 @@ function doorsAjar(state: GameState, viewerId: PlayerId | undefined, board: Asse
 }
 
 /** LOS including square-filling blockers. */
+function losWith(state: GameState, from: Cell, to: Cell, viewerId: PlayerId | undefined, stone: boolean): boolean {
+  const board = doorsAjar(state, viewerId, openedDoors(state, boardView(state)));
+  const blockers = losBlockers(state);
+  if (sightBetween(board, from, to, blockers)) return true;
+  if (!stone) return false;
+  const viewer = viewerId ? state.players.find((p) => p.id === viewerId) : undefined;
+  if (!viewer || !viewer.alive || !displays(viewer, "visionstone")) return false;
+  for (const key of Object.keys(board.edges)) {
+    if ((board.edges[key] ?? "open") === "open") continue;
+    const edges = { ...board.edges };
+    delete edges[key];
+    if (sightBetween({ ...board, edges }, from, to, blockers)) return true;
+  }
+  return false;
+}
+
+/** LOS including square-filling blockers. VISIONSTONE is the bearer's
+ * sight wherever sight is asked of them — creations, dispels, utility
+ * spells — not just attacks: one wall or door, any type, falls away.
+ * Safe at every revision: widening what a cast may target never changes
+ * how a recorded command replays. */
 export function gameLos(state: GameState, from: Cell, to: Cell, viewerId?: PlayerId): boolean {
-  return sightBetween(doorsAjar(state, viewerId, openedDoors(state, boardView(state))), from, to, losBlockers(state));
+  return losWith(state, from, to, viewerId, true);
+}
+
+/** The eye of an armed ambush. Springing is decided mid-move and lands
+ * in the ledger's flow, so this sight is frozen per game: before rev 3
+ * an ambush never looked through its owner's VISIONSTONE, and stored
+ * games must replay that blindness. */
+function ambushLos(state: GameState, owner: PlayerState, from: Cell, to: Cell): boolean {
+  return losWith(state, from, to, owner.id, (state.config.deckRev ?? 1) >= 3);
 }
 
 /** Parse an edge key back into its north/west cell and side. */
@@ -5167,8 +5199,8 @@ function checkAmbushes(
       sprung = context.pickedUpTreasure === true;
     } else if (context.movedFrom) {
       if (ambush.trigger.kind === "los") {
-        const before = gameLos(state, owner.position, context.movedFrom, owner.id);
-        const now = gameLos(state, owner.position, actor.position, owner.id);
+        const before = ambushLos(state, owner, owner.position, context.movedFrom);
+        const now = ambushLos(state, owner, owner.position, actor.position);
         sprung = now && !before;
       } else if (ambush.trigger.kind === "near") {
         const dist = (c: Cell) =>
@@ -5180,7 +5212,7 @@ function checkAmbushes(
 
     // The committed spell must be legal right now, or the ambush stays armed.
     const fx = CARD_EFFECTS[ambush.spell.cardId] as AttackEffect;
-    if (fx.requiresLos && !gameLos(state, owner.position, actor.position, owner.id)) continue;
+    if (fx.requiresLos && !ambushLos(state, owner, owner.position, actor.position)) continue;
 
     state.ambushes = state.ambushes.filter((a) => a.id !== ambush.id);
     state.discard.push(ambush.via, ambush.spell, ...ambush.numbers);