fix(street-level): settle loading on pan, keep zoom 0, drop late poses

Fixes from gekh's re-review of 061d269, each with a regression test that
fails on the old code:

- A pan that drops a tile still loading now settles the loading count
  (the aborted request no longer owns its key, so its `finally` never
  did), and purges the previous zoom's tiles once nothing is pending.
  LOADING no longer sticks on the status pill and chip.
- Zoom 0 (above 15,000 km) is a zoom: `zoom == null` instead of `!zoom`.
- A pose that arrives after a photo was closed is dropped, in the
  MapillaryJS adapter and in the viewer host, so the marker and sequence
  selection do not come back.
- Ground casting passes the tile's signal to the terrain request, so a
  cancelled tile stops its height batch instead of holding the queue.
- The server's in-memory tile cache honours the 24 h TTL like the disk.
- The viewer's one-time resize runs for every photo, not just the first.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

src/layers/streetLevel/providers/mapillary/coverage.js

@@ -537,7 +537,7 @@ export function createCoverage({ state, source }) {
     let bbox = visibleBbox(viewer);
     if (kind === 'overview' && (!bbox || zoom <= 1))
       bbox = [-180, -85, 180, 85];
-    if (!zoom || !bbox) {
+    if (zoom == null || !bbox) {
       state.coverage.hint =
         'Point the camera at the globe for street-level coverage';
       clear();
@@ -559,10 +559,14 @@ export function createCoverage({ state, source }) {
       if (!wanted.has(key)) removeTile(key);
     for (const [key, controller] of [...state.coverage.pending])
       if (!wanted.has(key)) {
+        // The aborted request no longer owns its key, so its `finally` will
+        // not settle the count: settle it here.
         controller.abort();
         state.coverage.pending.delete(key);
+        state.coverage.loading = Math.max(0, state.coverage.loading - 1);
       }
     for (const tile of tiles) loadTile(tile, kind);
+    if (!state.coverage.pending.size) purgeStale();
     // The camera moved: cells that were out of the sampler's range may not be.
     if (terrainMode())
       for (const entry of state.coverage.tiles.values())

src/layers/streetLevel/providers/mapillary/coverage.test.mjs

@@ -241,3 +241,39 @@ test('a tile whose lines cannot be cast is not rebuilt for nothing', async () =>
   assert.equal(viewer.scene.primitives.items.size, 0);
   coverage.clear();
 });
+
+test('panning off a tile that is still loading settles the loading count', async () => {
+  const { viewer, source, state, coverage } = setup();
+  coverage.refresh();
+  assert.equal(state.coverage.loading, 1);
+  // Same zoom, two tiles east: the first request is dropped, a new one starts.
+  viewer.view.lon += 0.05;
+  coverage.refresh();
+  assert.equal(source.calls.length, 2);
+  assert.equal(source.calls[0].signal.aborted, true);
+  assert.equal(state.coverage.pending.size, 1);
+  assert.equal(
+    state.coverage.loading,
+    1,
+    'only the live request counts as loading',
+  );
+  source.calls[0].reject(new DOMException('aborted', 'AbortError'));
+  source.calls[1].resolve(new Uint8Array());
+  await settle();
+  assert.equal(state.coverage.pending.size, 0);
+  assert.equal(state.coverage.loading, 0, 'LOADING clears');
+  coverage.clear();
+});
+
+test('zoom 0 is a zoom: the whole-earth view still shows coverage', () => {
+  const { viewer, source, state, coverage } = setup();
+  viewer.view.height = 20_000_000;
+  coverage.refresh();
+  assert.equal(state.coverage.zoom, 0);
+  assert.equal(state.coverage.hint, '');
+  assert.deepEqual(
+    source.calls.map((call) => call.key),
+    ['0/0/0'],
+  );
+  coverage.clear();
+});

src/layers/streetLevel/providers/mapillary/viewer.js

@@ -69,6 +69,9 @@ export function createMapillaryViewer({ source, render } = {}) {
         viewer.getPosition(),
         viewer.getPointOfView(),
       ]);
+      // Closed (or never opened) while the pose was in flight: a late
+      // `image` event must not bring the photo back.
+      if (pendingOpen === null) return;
       if (image) current = describe(image);
       if (!current || !viewer) return;
       emit({