test: restore wall thickness in golden fixture

demo/fixtures/visual-matrix.mjs

@@ -2,6 +2,25 @@
 
 const round = (value) => Number(value.toFixed(6));
 
+// Golden fixtures must use the same persisted wall-key contract as real plan
+// data. Arbitrary labels make every configured wall look virtual to the
+// renderer, which lets a visually ineffective baseline pass unnoticed.
+const WALL_KEY_PITCH = 1 / 240;
+const wallKey = (a, b) => {
+  const quantize = (value) => Math.round(value / WALL_KEY_PITCH) * WALL_KEY_PITCH;
+  const mx = quantize((a[0] + b[0]) / 2);
+  const my = quantize((a[1] + b[1]) / 2);
+  let dx = b[0] - a[0], dy = b[1] - a[1];
+  const length = Math.hypot(dx, dy);
+  if (length < 1e-12) { dx = 1; dy = 0; }
+  else { dx /= length; dy /= length; }
+  if (dx < -1e-12 || (Math.abs(dx) <= 1e-12 && dy < 0)) { dx = -dx; dy = -dy; }
+  let angle = Math.atan2(dy, dx);
+  if (angle < 0) angle += Math.PI;
+  const bucket = Math.round(angle * 1800) / 1800;
+  return `${mx.toFixed(4)},${my.toFixed(4)}@${bucket.toFixed(4)}`;
+};
+
 const uniqueEdges = (rooms) => {
   const edges = new Map();
   for (const room of rooms) {
@@ -16,7 +35,7 @@ const uniqueEdges = (rooms) => {
 };
 
 const wallsFor = (prefix, rooms, thickness) => uniqueEdges(rooms).map((edge, index) => ({
-  key: `${prefix}-wall-${index}`,
+  key: wallKey(edge.a, edge.b),
   a: edge.a,
   b: edge.b,
   cm: typeof thickness === 'function' ? thickness(edge, index) : thickness,