Rev 20: the junction wall rolls for its allegiance

The rulebook (Cards And Actions That Change The Map): a CREATE WALL
or DESTROY WALL alteration on a junction between sectors rolls a
50-50 when "some other moron" rotates one of them — 1-2 stays with
the standing sector, 3-4 travels with the moving one, per the book's
own low/high convention. Both rotation and relocation roll (the same
seam tears either way), demolished holes roll alongside conjured
walls, the pips land loud in the chronicle, and a traveling edge
rides anchored to its in-sector cell. Rev-gated: the roll consumes
dice that stored games never spent.

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

packages/engine/test/sight-illusions-sectors.test.ts

@@ -435,3 +435,31 @@ describe("relocation past the origin (rules rev 11)", () => {
     expect(state.boobytraps[0]!.realKey).toBe(cellKey(moved));
   });
 });
+
+describe("junction alterations roll for their sector (rules rev 20)", () => {
+  it("a conjured wall on the seam obeys the die: 1-2 stays, 3-4 travels", () => {
+    const { state: fresh } = createGame({ playerIds: ["a", "b"], seed: 42, sets: ["basic"], deckRev: 20 });
+    let state = toRound2(fresh);
+    // The 2p board is two sectors stacked: the seam runs between them.
+    const [p0, p1] = state.board.placements;
+    const seamY = Math.max(p0!.origin.y, p1!.origin.y) - 1;
+    const seamCell = { x: p0!.origin.x + 2, y: seamY };
+    const key = edgeKey(seamCell, "S");
+    // Conjure a wall on the seam (state surgery: the cast needs LOS we may lack).
+    state.edgeOverrides[key] = "wall";
+    state.createdEdges[key] = true;
+    const caster = activePlayer(state);
+    const rot = giveCard(state, caster.id, "rotate-sector");
+    const rngBefore = JSON.stringify(state.rng);
+    state = must(state, caster.id, {
+      type: "cast", instanceId: rot.instanceId,
+      target: { kind: "cell", cell: { x: p1!.origin.x + 2, y: p1!.origin.y + 2 } },
+      params: { clockwise: true },
+    });
+    // A die was consumed for the seam wall.
+    expect(JSON.stringify(state.rng)).not.toBe(rngBefore);
+    // The wall is somewhere: either the old seam key or a remapped edge.
+    const createdKeys = Object.keys(state.createdEdges);
+    expect(createdKeys.length).toBe(1);
+  });
+});