fix: stabilize opencode session startup

src/components/chat/hooks/useChatSessionState.ts

@@ -13,7 +13,6 @@ const MESSAGES_PER_PAGE = 20;
 const INITIAL_VISIBLE_MESSAGES = 100;
 
 type PendingViewSession = {
-  sessionId: string | null;
   startedAt: number;
 };
 
@@ -160,7 +159,7 @@ export function useChatSessionState({
      * Why this is essential:
      * - Chat keeps local state that is not fully derived from `selectedSession`:
      *   `currentSessionId`, `pendingUserMessage`, streaming/status flags, message
-     *   pagination/scroll bookkeeping, and pending session IDs in sessionStorage.
+     *   pagination/scroll bookkeeping, and provider-specific sessionStorage keys.
      * - If the user clicks New Session while already on the same route with no
      *   selected session, parent state updates can be idempotent and this local
      *   state would otherwise persist, making the click appear to "do nothing".
@@ -177,7 +176,6 @@ export function useChatSessionState({
     setIsLoading(false);
     setCurrentSessionId(null);
     setPendingUserMessage(null);
-    sessionStorage.removeItem('pendingSessionId');
     sessionStorage.removeItem('cursorSessionId');
     messagesOffsetRef.current = 0;
     setHasMoreMessages(false);
@@ -396,6 +394,12 @@ export function useChatSessionState({
   // Main session loading effect — store-based
   useEffect(() => {
     if (!selectedSession || !selectedProject) {
+      // A new provider run can be in flight before the router has a canonical
+      // selectedSession. Keep the processing banner alive until complete/error.
+      if (pendingViewSessionRef.current) {
+        return;
+      }
+
       resetStreamingState();
       pendingViewSessionRef.current = null;
       setClaudeStatus(null);
@@ -537,10 +541,6 @@ export function useChatSessionState({
     }
   }, [selectedSession]);
 
-  useEffect(() => {
-    if (selectedSession?.id) pendingViewSessionRef.current = null;
-  }, [pendingViewSessionRef, selectedSession?.id]);
-
   // Scroll to search target
   useEffect(() => {
     if (!searchTarget || chatMessages.length === 0 || isLoadingSessionMessages) return;