Restore snapshot to fix flaky render test after rework.

GitOrigin-RevId: f207f96b8ad5209fd472fff14fc78963d2bf5864

Author: dcoj

src/source/building_index.ts

@@ -114,6 +114,28 @@ class BuildingIndex {
         }
     }
 
+    /**
+     * Returns true if any building layer tracked by this index is backed by
+     * the source cache with the given `sourceCacheId`.  Used to detect when a
+     * fill-extrusion tile has finished loading so that a full label-placement
+     * pass can be requested: symbol z-offsets depend on building heights, so
+     * placement must re-run whenever new building data arrives.
+     *
+     * @param {string} sourceCacheId - The FQID of the source cache to check.
+     * @returns {boolean} `true` if a tracked building layer uses this cache.
+     * @example
+     * if (buildingIndex.hasLayerForSourceCache(event.sourceCacheId)) { ... }
+     */
+    hasLayerForSourceCache(sourceCacheId: string): boolean {
+        for (const {layer} of this.layers) {
+            const sourceCache = this.style.getLayerSourceCache(layer);
+            if (sourceCache && sourceCache.id === sourceCacheId) {
+                return true;
+            }
+        }
+        return false;
+    }
+
     _mapCoordToOverlappingTile(
         tid: OverscaledTileID,
         x: number,

src/ui/map.ts

@@ -4364,6 +4364,18 @@ export class Map extends Camera {
                 if (elevationSource && event.sourceCacheId === elevationSource.id && this.style) {
                     this.style._setLabelPlacementStale();
                 }
+                // Force a full label re-placement when a fill-extrusion (building)
+                // tile loads.  Symbol z-offsets are computed from building heights
+                // during placement, so if a building tile arrives after the initial
+                // placement pass (a common race when the symbol source is GeoJSON
+                // but buildings come from a separate vector tile source) the
+                // collision boxes and elevated symbol positions will be wrong.
+                // Re-running placement after the building data arrives ensures
+                // symbols appear at the correct elevation.
+                if (this.style && event.sourceCacheId &&
+                        this.style._buildingIndex.hasLayerForSourceCache(event.sourceCacheId)) {
+                    this.style._requestFullLabelPlacement();
+                }
                 this.painter.setTileLoadedFlag(true);
             }
         });

test/integration/render-tests/symbol-elevation/z-elevation-with-sort-by-viewport-y-and-collision-boxes/style.json

@@ -6,6 +6,7 @@
       "width": 256,
       "height": 256,
       "operations": [
+        ["waitFrameReady"]
       ],
       "image-threshold": [
         {"platform-tag-contains": "", "threshold": 0.0035}