fix(chat): enable in-place subtask navigation in embedded session-chat iframe (#2138)

packages/ui/src/hooks/useRouter.ts

@@ -5,6 +5,7 @@ import { parseRoute, updateBrowserURL, hasRouteParams } from '@/lib/router';
 import type { RouteState, AppRouteState } from '@/lib/router';
 import type { MainTab } from '@/stores/useUIStore';
 import { resolveSettingsSlug } from '@/lib/settings/metadata';
+import { isEmbeddedSessionChat } from '@/components/layout/contextPanelEmbeddedChat';
 
 /**
  * Check if running in VS Code webview context.
@@ -29,9 +30,18 @@ function isVSCodeContext(): boolean {
  * - Web: Full bidirectional sync
  * - Desktop: Full bidirectional sync
  * - VS Code: State-only (no URL updates, reads initial params)
+ * - Embedded session-chat iframe (`?ocPanel=session-chat`): No URL updates.
+ *   The iframe's session identity is fixed at mount (the parent builds the
+ *   src with `sessionId`); in-place subtask navigation must NOT rewrite the
+ *   URL, otherwise `ocPanel` (and `directory`/`readOnly`) get stripped and
+ *   `isEmbeddedSessionChat()` starts returning false, breaking subsequent
+ *   "Open subtask" clicks.
  */
 export function useRouter(): void {
   const isVSCode = React.useMemo(() => isVSCodeContext(), []);
+  // Captured once at mount: the iframe's embedded-ness never changes during
+  // its lifetime (a parent src swap is a full reload).
+  const isEmbeddedChat = React.useMemo(() => isEmbeddedSessionChat(), []);
 
   // Track initialization to avoid duplicate applies
   const initializedRef = React.useRef(false);
@@ -115,14 +125,14 @@ export function useRouter(): void {
    */
   const syncURLFromState = React.useCallback(
     (options: { replace?: boolean } = {}) => {
-      if (isVSCode || isApplyingRouteRef.current) {
+      if (isVSCode || isEmbeddedChat || isApplyingRouteRef.current) {
         return;
       }
 
       const state = getCurrentAppState();
       updateBrowserURL(state, options);
     },
-    [isVSCode, getCurrentAppState]
+    [isVSCode, isEmbeddedChat, getCurrentAppState]
   );
 
   // Initialize: parse URL and apply route on mount
@@ -148,7 +158,7 @@ export function useRouter(): void {
       // Use the parsed route values instead of an immediate store snapshot so
       // deep links do not briefly normalize `?session=...` back to `/` while
       // the session's directory/message bootstrap is still catching up.
-      if (!isVSCode) {
+      if (!isVSCode && !isEmbeddedChat) {
         updateBrowserURL({
           ...getCurrentAppState(),
           sessionId: route.sessionId ?? useSessionUIStore.getState().currentSessionId,
@@ -160,11 +170,11 @@ export function useRouter(): void {
     };
 
     void initializeRoute();
-  }, [applyRoute, getCurrentAppState, isVSCode]);
+  }, [applyRoute, getCurrentAppState, isVSCode, isEmbeddedChat]);
 
   // Subscribe to session changes
   React.useEffect(() => {
-    if (isVSCode) {
+    if (isVSCode || isEmbeddedChat) {
       return;
     }
 
@@ -183,11 +193,11 @@ export function useRouter(): void {
     });
 
     return unsubscribe;
-  }, [isVSCode, syncURLFromState]);
+  }, [isVSCode, isEmbeddedChat, syncURLFromState]);
 
   // Subscribe to UI store changes (tab, settings)
   React.useEffect(() => {
-    if (isVSCode) {
+    if (isVSCode || isEmbeddedChat) {
       return;
     }
 
@@ -220,11 +230,11 @@ export function useRouter(): void {
     });
 
     return unsubscribe;
-  }, [isVSCode, syncURLFromState]);
+  }, [isVSCode, isEmbeddedChat, syncURLFromState]);
 
   // Listen for browser back/forward navigation
   React.useEffect(() => {
-    if (typeof window === 'undefined' || isVSCode) {
+    if (typeof window === 'undefined' || isVSCode || isEmbeddedChat) {
       return;
     }
 
@@ -254,5 +264,5 @@ export function useRouter(): void {
     return () => {
       window.removeEventListener('popstate', handlePopState);
     };
-  }, [applyRoute, isVSCode, setActiveMainTab, setSettingsDialogOpen]);
+  }, [applyRoute, isVSCode, isEmbeddedChat, setActiveMainTab, setSettingsDialogOpen]);
 }