The dread wraps: fear's diamond continues from the opposite rim

The maze is a torus — a wizard walking through walls off one edge
arrives at the other, so the crow flies around the wrap too.
dreadDistance measures toroidal manhattan; the aura's wash wraps with
it. No rev-32 game has cast fear yet, so the measure corrects in
place; older vintages replay flat as they were played.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0138A8CjeQRpvzKxuMfz1Bqc

packages/engine/src/game.ts

@@ -3722,15 +3722,24 @@ function takeFromHand(p: PlayerState, instanceId: string): CardInstance | null {
  * monsters (rules rev 32 widened it beyond walking wizards; forced movement
  * such as knockback or a wave is not willing and passes).
  */
+/**
+ * FEAR's measure — FAQ: "as a Wizard walks (if he could walk through
+ * walls), not diagonally." Orthogonal steps, walls ignored — and the maze
+ * wraps, so stepping off one rim continues from the opposite one.
+ */
+function dreadDistance(board: AssembledBoard, a: Cell, b: Cell): number {
+  const dx = Math.abs(a.x - b.x);
+  const dy = Math.abs(a.y - b.y);
+  return Math.min(dx, board.width - dx) + Math.min(dy, board.height - dy);
+}
+
 function fearRepels(state: GameState, moverId: PlayerId | null, from: Cell, to: Cell): boolean {
+  const board = boardView(state);
   for (const other of state.players) {
     if (!other.alive || other.id === moverId) continue;
     if (sustainedOn(state, other.id, "fear").length === 0) continue;
-    // FAQ: "The 3 spaces away is measured as a Wizard walks (if he could
-    // walk through walls), not diagonally" — orthogonal steps, walls
-    // ignored. Warps do not carry the dread; walls do not shield from it.
-    const d = Math.abs(other.position.x - to.x) + Math.abs(other.position.y - to.y);
-    const dBefore = Math.abs(other.position.x - from.x) + Math.abs(other.position.y - from.y);
+    const d = dreadDistance(board, other.position, to);
+    const dBefore = dreadDistance(board, other.position, from);
     if (d <= 3 && d < dBefore) return true;
   }
   return false;

packages/web/src/Board.svelte

@@ -181,16 +181,21 @@
   });
 
   // FEAR's dread: three spaces in every direction, straight through walls
-  // ("even if walls separate you"), never diagonally — a manhattan diamond,
-  // the same measure the engine's refusal takes.
+  // ("even if walls separate you"), never diagonally — and the maze wraps,
+  // so the diamond continues from the opposite rim. Same measure the
+  // engine's refusal takes.
   const fearCells = $derived.by(() => {
     const out = new Set<string>();
+    const W = view.board.width;
+    const H = view.board.height;
     for (const fp of view.players) {
       if (!fp.alive) continue;
       if (!view.sustained.some((e) => e.cardId === "fear" && e.targetId === fp.id)) continue;
       for (let dx = -3; dx <= 3; dx++) {
         for (let dy = -3 + Math.abs(dx); dy <= 3 - Math.abs(dx); dy++) {
-          const k = `${fp.position.x + dx},${fp.position.y + dy}`;
+          const wx = ((fp.position.x + dx) % W + W) % W;
+          const wy = ((fp.position.y + dy) % H + H) % H;
+          const k = `${wx},${wy}`;
           if (view.board.cells[k]) out.add(k);
         }
       }