feat: add routable browser URLs for stacks and shell views (#1586)

* feat: add routable browser URLs for stacks and shell views

Sync in-memory navigation to the address bar via a History API hook so
deep links, refresh, Back/Forward, and bookmarks work across nodes,
views, stack editor tabs, and mobile surfaces. Gate role/tier URL
normalization on permissions and license readiness, preserve URLs on
metadata fetch failure, and surface retryable stack-list errors without
rewriting pending stack paths.

* fix: preserve deep-link views on cold load and refresh

Stop the node-switch effect from resetting to dashboard on initial mount.

Defer URL writer settlement until hydrated activeView matches the route.

Adds E2E coverage for shell cold loads, stack refresh, and compose env tab.

* fix: keep mobile dashboard on list surface so sidebar renders

On mobile, the URL sync hook was routing /nodes/<slug>/dashboard to the
content surface, hiding the stack list sidebar. This prevented the
data-stacks-loaded sentinel from appearing, causing sidebar truncation
E2E tests to time out after reload on a mobile viewport.

Mobile dashboard now stays on the list surface; other non-editor views
still render on the content surface.

* fix: complete mobile URL routing follow-ups for stack deep links

Restore mobile /dashboard vs /stacks, list surface always writes /stacks.

Hydrate pendingDetailStack, freeze compose failures with routeDetailError,

and add unit plus E2E coverage.

* fix: hydrate shell views from URL and sync in-app navigation

Bootstrap activeView and tab state from the pathname on cold load.

Settle route phase when state already matches, normalize unknown segments,

and open Monaco editor tabs from stack deep links via applyEditorRouteState.

* fix: prevent mobile stack deep links from hanging on cold load

The resolvePendingStack effect did not re-fire when the pending stack ref
was populated during URL hydration, because the urlHydratingStack state
set in the same callback was not listed in the effect's dependency array.
Adding it causes the effect to retry once hydration has committed.

A resolvingRef mutex prevents concurrent invocations. When the target file
is already loaded, route state is applied directly without calling
loadFileForRoute, which avoids unmounting the editor (and hiding the
recovery chip) if a background refresh triggers route resolution during
a deploy operation.

* test: adapt stack, deploy, and sidebar e2e specs to routable stack URLs

* ci: raise E2E Playwright job timeout to 20 minutes

frontend/src/components/EditorLayout/hooks/useStackListState.ts

@@ -64,6 +64,8 @@ export interface RemoteResult {
 
 const EMPTY_UPDATES: Record<string, StackUpdateInfo> = {};
 
+export type StacksLoadStatus = 'idle' | 'loading' | 'success' | 'error';
+
 export function useStackListState() {
   const { nodes, activeNode } = useNodes();
 
@@ -100,6 +102,10 @@ export function useStackListState() {
   const [filterChip, setFilterChip] = useState<FilterChip>('all');
   const [bulkMode, setBulkMode] = useState(false);
   const [selectedFiles, setSelectedFiles] = useState<Set<string>>(new Set());
+  const [stacksLoadStatus, setStacksLoadStatus] = useState<StacksLoadStatus>('idle');
+  const [stacksLoadError, setStacksLoadError] = useState<string | null>(null);
+  const [stacksLoadNodeId, setStacksLoadNodeId] = useState<number | null>(null);
+  const hadSuccessfulListRef = useRef(false);
 
   const { stackUpdates, refresh: fetchImageUpdates, sidebarIndicators } = useImageUpdates(activeNode?.id);
   const sidebarStackUpdates = sidebarIndicators ? stackUpdates : EMPTY_UPDATES;
@@ -117,6 +123,12 @@ export function useStackListState() {
     if (evictedOldest) toast.info('Pinned. Unpinned oldest (max 10).');
   }, [evictedOldest]);
 
+  useEffect(() => {
+    hadSuccessfulListRef.current = false;
+    setStacksLoadStatus('idle');
+    setStacksLoadError(null);
+  }, [activeNode?.id]);
+
   // Ref is updated synchronously alongside the state setter so any code that
   // runs right after (e.g. `refreshStacks(true)` in an action's finally block)
   // observes the cleared map before React commits the next render. Without
@@ -180,25 +192,39 @@ export function useStackListState() {
   }, [refreshLabels]);
 
   const refreshStacks = async (background = false): Promise<string[]> => {
-    if (!background) setIsLoading(true);
-    // Snapshot the node this fetch targets and a sequence token so a superseded
-    // or out-of-order resolution (from a rapid node switch) cannot overwrite a
-    // newer node's list, keeping `files` and `filesNodeId` consistent.
     const fetchNodeId = activeNode?.id ?? null;
     const mySeq = ++fetchSeqRef.current;
     const stale = () => fetchSeqRef.current !== mySeq;
+
+    if (!background) setIsLoading(true);
+    setStacksLoadNodeId(fetchNodeId);
+    if (!background || !hadSuccessfulListRef.current) {
+      setStacksLoadStatus('loading');
+      setStacksLoadError(null);
+    }
+
     try {
       const res = await apiFetch('/stacks');
       if (stale()) return [];
       if (!res.ok) {
+        const message = `Could not load stacks (${res.status})`;
+        if (background && hadSuccessfulListRef.current) {
+          setStacksLoadError(message);
+          return files;
+        }
         setFiles([]);
         setFilesNodeId(fetchNodeId);
+        setStacksLoadStatus('error');
+        setStacksLoadError(message);
         return [];
       }
       const data = await res.json();
       const fileList: string[] = Array.isArray(data) ? data : [];
       setFiles(fileList);
       setFilesNodeId(fetchNodeId);
+      hadSuccessfulListRef.current = true;
+      setStacksLoadStatus('success');
+      setStacksLoadError(null);
 
       // Fetch all stack statuses in a single bulk call. Only the current object
       // format can express `partial`; a node lacking the endpoint or returning
@@ -244,8 +270,15 @@ export function useStackListState() {
     } catch (error) {
       if (stale()) return [];
       console.error('Failed to refresh stacks:', error);
+      const message = error instanceof Error ? error.message : 'Failed to load stacks';
+      if (background && hadSuccessfulListRef.current) {
+        setStacksLoadError(message);
+        return files;
+      }
       setFiles([]);
       setFilesNodeId(fetchNodeId);
+      setStacksLoadStatus('error');
+      setStacksLoadError(message);
       return [];
     } finally {
       setIsLoading(false);
@@ -434,5 +467,8 @@ export function useStackListState() {
     isCollapsed, toggleCollapse,
     remoteSearchLoading,
     remoteSearchFailedNodes,
+    stacksLoadStatus,
+    stacksLoadError,
+    stacksLoadNodeId,
   } as const;
 }