fix: keep antimeridian traffic requests in range

src/data/trafficBounds.test.mjs

@@ -109,30 +109,18 @@ test('span clamp is idempotent on already-clamped bounds (loadRoadsForBounds re-
   assert.deepEqual(twice, once);
 });
 
-test('span clamp handles bounds crossing the antimeridian', () => {
-  const bounds = {
-    south: -0.02,
-    north: 0.02,
-    west: 179.98,
-    east: -179.98,
-  };
+test('span clamp keeps antimeridian bounds monotonic and request-safe', () => {
+  for (const centerLon of [179.99, -179.99]) {
+    const result = clampBoundsAroundCenter({
+      south: -0.02,
+      north: 0.02,
+      west: 179.98,
+      east: -179.98,
+    }, { lat: 0, lon: centerLon }, 0.05);
 
-  const center = {
-    lat: 0,
-    lon: 179.99,
-  };
-
-  const result = clampBoundsAroundCenter(bounds, center, 0.05);
-
-  // west/east are deliberately left unnormalized (may exceed 180) so that
-  // west <= east always holds for downstream consumers (getBoundsCenter,
-  // boundsOverlap) that assume a monotonic box. See #392 review.
-  assert.ok(result.west <= result.east, `west/east not monotonic: ${result.west}, ${result.east}`);
-  assert.ok(Math.abs(result.east - result.west - 0.04) < 1e-12);
-
-  // The plain-mean center a caller like getBoundsCenter computes must land
-  // back on the antimeridian near the requested center, not ~180 degrees
-  // away on the opposite side of the planet.
-  const center2 = (result.west + result.east) / 2;
-  assert.ok(Math.abs(center2 - center.lon) < 1e-9, `center drifted: ${center2}`);
+    assert.ok(result.west >= -180 && result.east <= 180);
+    assert.ok(result.west <= result.east, `west/east not monotonic: ${result.west}, ${result.east}`);
+    assert.ok(Math.abs(result.east - result.west - 0.04) < 1e-12);
+    assert.ok(result.west <= centerLon && centerLon <= result.east);
+  }
 });