feat(cli): handle invalid model names in useQuotaAndFallback (#19222)

packages/cli/src/ui/hooks/useQuotaAndFallback.test.ts

@@ -341,6 +341,46 @@ Your admin might have disabled the access. Contact them to enable the Preview Re
 
         expect(result.current.proQuotaRequest).toBeNull();
       });
+
+      it('should handle ModelNotFoundError with invalid model correctly', async () => {
+        const { result } = renderHook(() =>
+          useQuotaAndFallback({
+            config: mockConfig,
+            historyManager: mockHistoryManager,
+            userTier: UserTierId.FREE,
+            setModelSwitchedFromQuotaError: mockSetModelSwitchedFromQuotaError,
+            onShowAuthSelection: mockOnShowAuthSelection,
+          }),
+        );
+
+        const handler = setFallbackHandlerSpy.mock
+          .calls[0][0] as FallbackModelHandler;
+
+        let promise: Promise<FallbackIntent | null>;
+        const error = new ModelNotFoundError('model not found', 404);
+
+        act(() => {
+          promise = handler('invalid-model', 'gemini-2.5-pro', error);
+        });
+
+        const request = result.current.proQuotaRequest;
+        expect(request).not.toBeNull();
+        expect(request?.failedModel).toBe('invalid-model');
+        expect(request?.isModelNotFoundError).toBe(true);
+
+        const message = request!.message;
+        expect(message).toBe(
+          `Model "invalid-model" was not found or is invalid.
+/model to switch models.`,
+        );
+
+        act(() => {
+          result.current.handleProQuotaChoice('retry_always');
+        });
+
+        const intent = await promise!;
+        expect(intent).toBe('retry_always');
+      });
     });
   });