diff --git a/src/app/catalog.test.mjs b/src/app/catalog.test.mjs
index 56a96c1ed..91d7e8ce1 100644
--- a/src/app/catalog.test.mjs
+++ b/src/app/catalog.test.mjs
@@ -256,3 +256,45 @@ test('a catalog for an engine gives stand-ins only for the layers it leaves out'
     /Control layer missing from catalog: traffic/,
   );
 });
+
+test('a teardown during startup ends the wait for a stalled layer attachment', async (t) => {
+  const previous = globalThis.document;
+  globalThis.document = { getElementById: () => null };
+  t.after(() => {
+    if (previous === undefined) delete globalThis.document;
+    else globalThis.document = previous;
+  });
+  const layer = {
+    id: 'slow',
+    init: () => true,
+    enable: () => true,
+    update: () => true,
+    disable: () => true,
+    destroy: () => true,
+    attachRenderer: (viewer) =>
+      viewer?.second ? new Promise(() => {}) : undefined,
+    detachRenderer() {},
+  };
+  const layerSession = { lifetime: new AbortController() };
+  const start = (viewer, signal = null) => {
+    const releases = [];
+    const data = createApplicationData({
+      scene: { viewer },
+      controls: { styleManager: { attachDataManager() {} } },
+      catalog: createLayerCatalog([layer], metadata([layer])),
+      layerSession,
+      signal,
+      defer: (release) => releases.push(release),
+    });
+    return { data, releases };
+  };
+  const first = start({ first: true });
+  assert.equal(await layerSession.manager.setEnabled('slow', true), true);
+  for (const release of first.releases.reverse()) await release();
+
+  const application = new AbortController();
+  const second = start({ second: true }, application.signal);
+  application.abort();
+  const { dataManager } = await second.data;
+  assert.equal(dataManager, layerSession.manager);
+});
diff --git a/src/app/data.js b/src/app/data.js
index 58df1d9cc..24fd391cc 100644
--- a/src/app/data.js
+++ b/src/app/data.js
@@ -11,17 +11,20 @@ export function createApplicationData({
   layerSession,
   onData,
   defer,
+  signal = null,
 }) {
   // Initialize data layer manager
   // The modules get { signal, engine } on every call (viewer null on Navara).
-  const dataManager = layerSession?.manager ?? new LayerLifecycle(viewer, {
-    engine,
-    allowQaRegistration,
-    // A panel's host may report it hidden while it is on screen; its layers
-    // keep polling (see keepPanelRendering in embed.js).
-    visibilityTarget: panelAwareVisibility(document),
-    getSourceAvailability: catalog?.getSourceAvailability,
-  });
+  const dataManager =
+    layerSession?.manager ??
+    new LayerLifecycle(viewer, {
+      engine,
+      allowQaRegistration,
+      // A panel's host may report it hidden while it is on screen; its layers
+      // keep polling (see keepPanelRendering in embed.js).
+      visibilityTarget: panelAwareVisibility(document),
+      getSourceAvailability: catalog?.getSourceAvailability,
+    });
   if (layerSession) layerSession.manager = dataManager;
   defer(async () => {
     if (layerSession && !layerSession.lifetime.signal.aborted) {
@@ -34,12 +37,15 @@ export function createApplicationData({
         `Data layers could not be destroyed: ${[...dataManager.layers.keys()].join(', ')}`,
       );
   });
-  const presentation = layerSession?.presentation ?? new LayerPresentation(dataManager, {
-    weatherClock: catalog?.weatherClock,
-  });
+  const presentation =
+    layerSession?.presentation ??
+    new LayerPresentation(dataManager, {
+      weatherClock: catalog?.weatherClock,
+    });
   if (layerSession) layerSession.presentation = presentation;
   defer(() => {
-    if (layerSession && !layerSession.lifetime.signal.aborted) presentation.suspend();
+    if (layerSession && !layerSession.lifetime.signal.aborted)
+      presentation.suspend();
     else presentation.destroy();
   });
   onData?.(dataManager);
@@ -47,7 +53,9 @@ export function createApplicationData({
     throw new TypeError('An application layer catalog is required');
   for (const layer of catalog.layers)
     layer.attachMapStackController?.(mapStackController);
-  const attached = dataManager.bindCatalog(viewer, engine, catalog, { waitForCameraRestore: layerSession?.restoringView === true });
+  const attached = dataManager.bindCatalog(viewer, engine, catalog, {
+    waitForCameraRestore: layerSession?.restoringView === true,
+  });
   for (const layer of catalog.layers) layer.attachDataManager?.(dataManager);
 
   if (allowQaRegistration) {
@@ -70,11 +78,31 @@ export function createApplicationData({
         delete window.__gevQaUnregisterLayer;
     });
   }
-  presentation.mount(document.getElementById('data-toggles'), catalog.weatherClock);
+  presentation.mount(
+    document.getElementById('data-toggles'),
+    catalog.weatherClock,
+  );
   styleManager.attachDataManager(dataManager);
   // The sonar scene draws on the viewer; the Navara engine has none.
   if (viewer) defer(createCyberSonarScene(viewer, dataManager));
 
   const data = { dataManager, catalog, presentation };
-  return attached ? attached.then(() => data) : data;
+  if (!attached) return data;
+  // A teardown during startup must not wait for slow layer attachments: it
+  // ends this wait, and the data cleanup above releases the scene.
+  return new Promise((resolve, reject) => {
+    const onAbort = () => resolve(data);
+    if (signal?.aborted) onAbort();
+    else signal?.addEventListener('abort', onAbort, { once: true });
+    attached.then(
+      () => {
+        signal?.removeEventListener('abort', onAbort);
+        resolve(data);
+      },
+      (error) => {
+        signal?.removeEventListener('abort', onAbort);
+        reject(error);
+      },
+    );
+  });
 }