fix: clear retry error messages promptly after auto-retry succeeds

Previously, when an auto-retry countdown elapsed and the server sent a
Retry event (without retryInfo) to signal the actual retry attempt, the
error message was not cleared because `pendingRetryCountdownItemRef` was
still set. This caused stale error messages to persist in the UI until
the user manually initiated a new request.

Additionally, when the user pressed Ctrl+Y to retry, the error was
committed to history (without hint) instead of being discarded. This was
inconsistent with the auto-retry behavior where errors are silently
cleared on success.

Changes:
- Always call clearRetryCountdown() when a Retry event without retryInfo
  is received, removing the flawed guard condition
- Remove error-to-history commit in retryLastPrompt for consistent UX
- Add test covering the countdown-elapsed retry scenario

Closes #2310

Made-with: Cursor

packages/cli/src/ui/hooks/useGeminiStream.ts

@@ -1034,7 +1034,8 @@ export const useGeminiStream = (
             // Show retry info if available (rate-limit / throttling errors)
             if (event.retryInfo) {
               startRetryCountdown(event.retryInfo);
-            } else if (!pendingRetryCountdownItemRef.current) {
+            } else {
+              // The retry attempt is starting now, so any prior retry UI is stale.
               clearRetryCountdown();
             }
             break;
@@ -1075,7 +1076,6 @@ export const useGeminiStream = (
       setThought,
       pendingHistoryItemRef,
       setPendingHistoryItem,
-      pendingRetryCountdownItemRef,
     ],
   );
 
@@ -1301,24 +1301,13 @@ export const useGeminiStream = (
       return;
     }
 
-    // Commit the error to history (without hint) before clearing
-    const errorItem = pendingRetryErrorItemRef.current;
-    if (errorItem) {
-      addItem({ type: errorItem.type, text: errorItem.text }, Date.now());
-    }
     clearRetryCountdown();
 
     await submitQuery(lastPrompt, {
       isContinuation: false,
       skipPreparation: true,
     });
-  }, [
-    streamingState,
-    addItem,
-    clearRetryCountdown,
-    submitQuery,
-    pendingRetryErrorItemRef,
-  ]);
+  }, [streamingState, addItem, clearRetryCountdown, submitQuery]);
 
   const handleApprovalModeChange = useCallback(
     async (newApprovalMode: ApprovalMode) => {