Rev 15: the held doorway carries sight — the whole point of holding it

The table holds doors open to cast back through them at pursuers;
our held door opened for feet but not for eyes. From rev 15 a held
door is an open doorway to sight — casting at players, creatures,
and squares sees through it, the client's dimming aid and the
automatons alike (they share sightedCellsFor). REMOVE LOCK's "still
considered to block L.O.S." stands: that speaks of a CLOSED door,
and an unheld unlocked door still blocks. Rev-gated because rev-14
ledgers may already contain holds and must replay blind.

Pinned three ways: the holder blasts a pursuer through the held
doorway; an unheld unlocked door still blocks; rev 14 stays blind.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

packages/engine/src/game.ts

@@ -326,9 +326,19 @@ export function losBlockers(state: GameState): Record<string, true> {
   return blockers;
 }
 
+/** A held-open door is an open doorway to the eye (rules rev 15): REMOVE
+ * LOCK's "still considered to block L.O.S." speaks of a CLOSED door, and
+ * the table holds doors open precisely to cast back through them. */
+function openHeldDoors(state: GameState, board: AssembledBoard): AssembledBoard {
+  if ((state.config.deckRev ?? 1) < 15 || state.heldDoors.length === 0) return board;
+  const edges = { ...board.edges };
+  for (const h of state.heldDoors) delete edges[h.key];
+  return { ...board, edges };
+}
+
 /** LOS including square-filling blockers. */
 export function gameLos(state: GameState, from: Cell, to: Cell): boolean {
-  return sightBetween(boardView(state), from, to, losBlockers(state));
+  return sightBetween(openHeldDoors(state, boardView(state)), from, to, losBlockers(state));
 }
 
 /** Parse an edge key back into its north/west cell and side. */
@@ -404,7 +414,7 @@ function casterLos(
   to: Cell,
   events: GameEvent[] = [],
 ): boolean {
-  const board = perceivedBoard(state, events, caster.id, { from, to });
+  const board = openHeldDoors(state, perceivedBoard(state, events, caster.id, { from, to }));
   const blockers = losBlockers(state);
   if (sightBetween(board, from, to, blockers)) return true;
   if (!displays(caster, "visionstone")) return false;

packages/engine/src/view.ts

@@ -173,6 +173,13 @@ export function sightedCellsFor(view: GameView): Set<string> {
   const out = new Set<string>();
   const me = view.players.find((p) => p.id === view.you);
   if (!me) return out;
+  // Held-open doors are open doorways to the eye (rules rev 15).
+  let board = view.board;
+  if (view.deckRev >= 15 && view.heldDoorEdges.length > 0) {
+    const edges = { ...board.edges };
+    for (const k of view.heldDoorEdges) delete edges[k];
+    board = { ...board, edges };
+  }
   const blockers: Record<string, true> = {};
   for (const [key, content] of Object.entries(view.squareContents)) {
     if (LOS_BLOCKING_CONTENT[content.kind]) blockers[key] = true;
@@ -182,9 +189,9 @@ export function sightedCellsFor(view: GameView): Set<string> {
       blockers[`${p.position.x},${p.position.y}`] = true;
     }
   }
-  for (const key of Object.keys(view.board.cells)) {
+  for (const key of Object.keys(board.cells)) {
     const [x, y] = key.split(",").map(Number) as [number, number];
-    if (sightBetween(view.board, me.position, { x, y }, blockers)) out.add(key);
+    if (sightBetween(board, me.position, { x, y }, blockers)) out.add(key);
   }
   return out;
 }