fix(routing): split stack detail URL from compose editor URL (#1605)

Sidebar opens /stacks/:name (anatomy). Monaco uses /compose|/env|/files.
Refresh of a detail URL no longer opens the editor, and editor deep links
keep a hydration shell instead of flashing the dashboard.

frontend/src/lib/router/readUrlRouteState.ts

@@ -19,6 +19,13 @@ const DEFAULT: UrlRouteState = {
   filterNodeId: null,
 };
 
+/** True when the current URL is a stack workspace deep link (detail or editor). */
+export function isStackEditorDeepLink(): boolean {
+  if (typeof window === 'undefined') return false;
+  const parsed = parsePath(window.location.pathname, window.location.search);
+  return parsed.view === 'editor' && parsed.stackName != null;
+}
+
 /** Read shell navigation fields from the current browser URL (cold-load bootstrap). */
 export function readUrlRouteState(): UrlRouteState {
   if (typeof window === 'undefined') return DEFAULT;

frontend/src/lib/router/routeTypes.ts

@@ -34,7 +34,11 @@ export interface RouteState {
   activeView: ActiveView;
   /** Stack directory name when activeView is editor or host-console. */
   stackName: string | null;
-  editorTab: EditorTab;
+  /**
+   * Monaco editor tab when the compose/env/files surface is open.
+   * Null means stack detail (anatomy) at `/stacks/:name` with no tab segment.
+   */
+  editorTab: EditorTab | null;
   envFile: string | null;
   securityTab: SecurityTab;
   fleetActiveTab: FleetTab;

frontend/src/lib/router/senchoRoute.test.ts

@@ -131,4 +131,30 @@ describe('senchoRoute', () => {
     expect(parsed.isStackList).toBe(true);
     expect(parsed.stackName).toBeNull();
   });
+
+  it('round-trips stack detail without a tab segment', () => {
+    const path = buildPath({
+      ...base,
+      activeView: 'editor',
+      stackName: 'radarr',
+      editorTab: null,
+    });
+    expect(path).toBe('/nodes/local/stacks/radarr');
+    const parsed = parsePath(path, '');
+    expect(parsed.view).toBe('editor');
+    expect(parsed.stackName).toBe('radarr');
+    expect(parsed.editorTab).toBeNull();
+  });
+
+  it('parses compose tab as Monaco editor, not detail', () => {
+    const parsed = parsePath('/nodes/local/stacks/radarr/compose', '');
+    expect(parsed.view).toBe('editor');
+    expect(parsed.editorTab).toBe('compose');
+  });
+
+  it('treats unknown stack tab segment as detail', () => {
+    const parsed = parsePath('/nodes/local/stacks/radarr/anatomy', '');
+    expect(parsed.view).toBe('editor');
+    expect(parsed.editorTab).toBeNull();
+  });
 });

frontend/src/lib/router/senchoRoute.ts

@@ -95,16 +95,18 @@ export function parsePath(pathname: string, search: string): ParsedRoute {
     }
     const stackName = parts[3];
     const tabRaw = parts[4]?.toLowerCase();
+    // No tab segment → stack detail (anatomy). A valid tab opens Monaco.
+    // Unknown fifth segments are treated as detail, not as compose.
     const editorTab = tabRaw && EDITOR_TABS.has(tabRaw as EditorTab)
       ? (tabRaw as EditorTab)
-      : 'compose';
+      : null;
     return {
       ...empty,
       nodeSlug,
       view: 'editor',
       stackName,
       editorTab,
-      envFile: envFile || null,
+      envFile: editorTab === 'env' ? (envFile || null) : null,
       filterNodeId,
     };
   }
@@ -138,10 +140,14 @@ export function buildPath(state: RouteState): string {
   const url = new URL('http://local');
 
   if (state.activeView === 'editor' && state.stackName) {
-    const tab = state.editorTab || 'compose';
-    url.pathname = `${base}/stacks/${encodeURIComponent(state.stackName)}/${tab}`;
-    if (tab === 'env' && state.envFile && !/[\\/]/.test(state.envFile)) {
-      url.searchParams.set('env', state.envFile);
+    const stackBase = `${base}/stacks/${encodeURIComponent(state.stackName)}`;
+    if (state.editorTab == null) {
+      url.pathname = stackBase;
+    } else {
+      url.pathname = `${stackBase}/${state.editorTab}`;
+      if (state.editorTab === 'env' && state.envFile && !/[\\/]/.test(state.envFile)) {
+        url.searchParams.set('env', state.envFile);
+      }
     }
     if (state.filterNodeId != null) {
       url.searchParams.set('node', String(state.filterNodeId));