fix(webui): delete unpersisted pane sessions (#5624)

Co-authored-by: chengyongru <chengyongru.ai@gmail.com>

webui/src/hooks/useSessions.ts

@@ -257,11 +257,14 @@ export function useSessions(): {
 
   const deleteChat = useCallback(
     async (key: string, options?: { deleteAutomations?: boolean }) => {
+      const optimistic = optimisticKeysRef.current.has(key);
       const result = await apiDeleteSession(client, key, options);
-      if (!result.deleted) return result;
+      if (result.blocked_by_automations || (!result.deleted && !optimistic)) return result;
       optimisticKeysRef.current.delete(key);
       setSessions((prev) => prev.filter((s) => s.key !== key));
-      return result;
+      // The gateway may have restarted and forgotten an unpersisted chat's
+      // draft scope, but removing that optimistic session is still a deletion.
+      return result.deleted ? result : { ...result, deleted: true };
     },
     [client],
   );