Harden gameplay timing and map loading

lib/panorama-textures.ts

@@ -0,0 +1,44 @@
+import * as THREE from "three";
+
+// Each viewer owns its textures. Browser HTTP caching handles repeat downloads;
+// keeping GPU resources in a global cache leaks every visited map and signed URL.
+export async function loadPanoramaTextures(
+  urls: string[],
+  loader: Pick<THREE.TextureLoader, "loadAsync"> = new THREE.TextureLoader(),
+  timeoutMs = 30000,
+): Promise<THREE.Texture[]> {
+  const textures: THREE.Texture[] = [];
+  let failed = false;
+  let timer: ReturnType<typeof setTimeout> | undefined;
+  try {
+    return await Promise.race([
+      Promise.all(
+        urls.map(async (url) => {
+          const texture = await loader.loadAsync(url);
+          if (failed) {
+            texture.dispose();
+            throw new Error("Panorama loading cancelled");
+          }
+          texture.colorSpace = THREE.SRGBColorSpace;
+          textures.push(texture);
+          return texture;
+        }),
+      ),
+      new Promise<never>((_, reject) => {
+        timer = setTimeout(
+          () =>
+            reject(
+              new Error("Panorama loading timed out. Reconnect to retry."),
+            ),
+          timeoutMs,
+        );
+      }),
+    ]);
+  } catch (error) {
+    failed = true;
+    textures.forEach((texture) => texture.dispose());
+    throw error;
+  } finally {
+    clearTimeout(timer);
+  }
+}