Around the Corner bends every spell, hairpins included

Two holes, found when a SAFE cast at a treasure 'around the 180 degree
corner' refused with no line of sight (room LZ5R). First: the bend was
honored only in the attack path — every neutral resolve (creations,
summons, utilities, edge targets) checked straight sight and ignored
the attached card, though the card says 'any line of sight spell'.
castSight/castSightEdge now thread the bend through all of them, and
the chronicle narrates the neutral bend too.

Second: the bend itself pivoted only at cell centers, so the card's
flagship shot — doubling back up to 180 degrees around a wall's end —
never resolved: both legs graze the corner and die. The pivot may now
sit in the wall's open gap itself (bentSightThroughGap), which is what
rounding a corner physically is. Closed doors still block; two corners
still refuse.

The client lights bent-reachable squares for real now instead of the
old one-step-adjacency guess, creations included. Pure widening, so no
rev bump: every one of these casts was refused before, so no ledger
holds one. All 26 production ledgers replay clean; the LZ5R moment
itself replayed and the exact refused cast now lands.

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

packages/engine/src/board.ts

@@ -480,3 +480,34 @@ export function sightBetween(
   return hasLineOfSight(board, from, to, blockedCells) ||
          hasWarpLineOfSight(board, from, to, blockedCells);
 }
+
+/**
+ * AROUND THE CORNER's full reach: "around one corner (up to 180 degrees)".
+ * A hairpin around the end of a wall pivots IN the wall's gap, not at any
+ * cell's center — so try the midpoint of every open edge as the bend point,
+ * with a clear straight segment from caster to pivot and pivot to target.
+ */
+export function bentSightThroughGap(
+  board: AssembledBoard,
+  from: Cell,
+  to: Cell,
+  blockedCells?: Record<string, true>,
+): boolean {
+  const fx = from.x + 0.5, fy = from.y + 0.5;
+  const tx = to.x + 0.5, ty = to.y + 0.5;
+  const skip = [cellKey(from), cellKey(to)];
+  for (const key of Object.keys(board.cells)) {
+    const [x, y] = key.split(",").map(Number) as [number, number];
+    const c = { x, y };
+    for (const side of ["E", "S"] as Side[]) {
+      if (!board.cells[cellKey(neighbor(c, side))]) continue;
+      if (edgeState(board, c, side) !== "open") continue;
+      const [px, py] = side === "E" ? [x + 1, y + 0.5] : [x + 0.5, y + 1];
+      if (segmentClear(board, fx, fy, px, py, blockedCells, skip) &&
+          segmentClear(board, px, py, tx, ty, blockedCells, skip)) {
+        return true;
+      }
+    }
+  }
+  return false;
+}