feat(plan): refactor ToolConfirmationPayload to union type (#17980)

packages/core/src/scheduler/tool-modifier.test.ts

@@ -193,13 +193,46 @@ describe('ToolModificationHandler', () => {
 
       const result = await handler.applyInlineModify(
         mockWaitingToolCall,
-        { newContent: undefined } as unknown as ToolConfirmationPayload,
+        {} as ToolConfirmationPayload, // no newContent property
         new AbortController().signal,
       );
 
       expect(result).toBeUndefined();
     });
 
+    it('should process empty string as valid new content', async () => {
+      vi.mocked(
+        modifiableToolModule.isModifiableDeclarativeTool,
+      ).mockReturnValue(true);
+      (Diff.createPatch as unknown as Mock).mockReturnValue('mock-diff-empty');
+
+      mockModifyContext.getCurrentContent.mockResolvedValue('old content');
+      mockModifyContext.getFilePath.mockReturnValue('test.txt');
+      mockModifyContext.createUpdatedParams.mockReturnValue({
+        content: '',
+      });
+
+      const mockWaitingToolCall = createMockWaitingToolCall({
+        tool: mockModifiableTool,
+      });
+
+      const result = await handler.applyInlineModify(
+        mockWaitingToolCall,
+        { newContent: '' },
+        new AbortController().signal,
+      );
+
+      expect(mockModifyContext.createUpdatedParams).toHaveBeenCalledWith(
+        expect.any(String),
+        '',
+        expect.any(Object),
+      );
+      expect(result).toEqual({
+        updatedParams: { content: '' },
+        updatedDiff: 'mock-diff-empty',
+      });
+    });
+
     it('should calculate diff and return updated params', async () => {
       vi.mocked(
         modifiableToolModule.isModifiableDeclarativeTool,