Idiot enforces its card (rev 23) + attack sight-line tracing

Rules rev 23 — IDIOT, per the card and FAQ:
- No handling items: pick up / drop of treasures and objects refused
  (dropping was the exploit: capturing a stolen treasure on your own home,
  or dropping your own treasure underfoot for an instant cure)
- No punching, no thrown dagger / large rock (attacks on players)
- No effect on a victim already carrying one of their own treasures
Ungated (permissive): counteractions are now castable while idiotized (the
one thing the card expressly allows — the gate wrongly blocked them), and
goal-aiding spells (IDIOT_AIDS: destroy-wall, teleport, mad-dash, ...) per
the FAQ's 'you could, however, destroy a wall'.

Sight tracing: while an LOS attack sits on the stack, the board draws the
line it traveled — straight when direct, leg by leg through both warp
mouths (with pulsing rings) when the maze's wraparound carried it. Engine
traceSight/traceSightFor/stackSightTrace; overlay in Board.svelte; shown
live and in replays. Verified against H3PC's cross-board Idiot cast.

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

packages/engine/src/board.ts

@@ -360,6 +360,41 @@ export function hasWarpLineOfSight(
   to: Cell,
   blockedCells?: Record<string, true>,
 ): boolean {
+  return warpSightTrace(board, from, to, blockedCells) !== null;
+}
+
+/**
+ * How a sight line reached its target — the material for drawing it. A warp
+ * trace carries the two mouths and the exact rim-crossing points (in board
+ * coordinates, where cell (x,y) spans [x,x+1]) so a renderer can draw the
+ * near leg to `entry` and the far leg from `exit`.
+ */
+export type SightTrace =
+  | { kind: "direct" }
+  | {
+      kind: "warp";
+      mouthA: { cell: Cell; side: Side };
+      mouthB: { cell: Cell; side: Side };
+      entry: { x: number; y: number };
+      exit: { x: number; y: number };
+    };
+
+export function traceSight(
+  board: AssembledBoard,
+  from: Cell,
+  to: Cell,
+  blockedCells?: Record<string, true>,
+): SightTrace | null {
+  if (hasLineOfSight(board, from, to, blockedCells)) return { kind: "direct" };
+  return warpSightTrace(board, from, to, blockedCells);
+}
+
+function warpSightTrace(
+  board: AssembledBoard,
+  from: Cell,
+  to: Cell,
+  blockedCells?: Record<string, true>,
+): Extract<SightTrace, { kind: "warp" }> | null {
   const DIR: Record<Side, { x: number; y: number }> = {
     N: { x: 0, y: -1 }, S: { x: 0, y: 1 }, E: { x: 1, y: 0 }, W: { x: -1, y: 0 },
   };
@@ -423,10 +458,16 @@ export function hasWarpLineOfSight(
       segmentClear(board, Pfar.x, Pfar.y, to.x + 0.5, to.y + 0.5, blockedCells,
         [cellKey(to), cellKey(mouthB)])
     ) {
-      return true;
+      return {
+        kind: "warp",
+        mouthA: { cell: mouthA, side: sideA },
+        mouthB: { cell: mouthB, side: w.to.side },
+        entry: P,
+        exit: Pfar,
+      };
     }
   }
-  return false;
+  return null;
 }
 
 /** The game's full line-of-sight check: direct, or through a wraparound opening. */