fix: ensure write_to_file returns error response to LLM on failure

- Add pushToolResult() call in error handler to return formatted error message
- Extract toolProtocol from callbacks for error formatting
- Update test to verify pushToolResult is called with error message
- Fixes ROO-320: UI buttons getting stuck after file write errors

src/core/tools/WriteToFileTool.ts

@@ -34,7 +34,7 @@ export class WriteToFileTool extends BaseTool<"write_to_file"> {
 	}
 
 	async execute(params: WriteToFileParams, task: Task, callbacks: ToolCallbacks): Promise<void> {
-		const { pushToolResult, handleError, askApproval, removeClosingTag } = callbacks
+		const { pushToolResult, handleError, askApproval, removeClosingTag, toolProtocol } = callbacks
 		const relPath = params.path
 		let newContent = params.content
 
@@ -194,6 +194,7 @@ export class WriteToFileTool extends BaseTool<"write_to_file"> {
 			return
 		} catch (error) {
 			await handleError("writing file", error as Error)
+			pushToolResult(formatResponse.toolError((error as Error).message, toolProtocol))
 			await task.diffViewProvider.reset()
 			this.resetPartialState()
 			return

src/core/tools/__tests__/writeToFileTool.spec.ts

@@ -443,12 +443,13 @@ describe("writeToFileTool", () => {
 	})
 
 	describe("error handling", () => {
-		it("handles general file operation errors", async () => {
+		it("handles general file operation errors and returns error to LLM", async () => {
 			mockCline.diffViewProvider.open.mockRejectedValue(new Error("General error"))
 
 			await executeWriteFileTool({})
 
 			expect(mockHandleError).toHaveBeenCalledWith("writing file", expect.any(Error))
+			expect(mockPushToolResult).toHaveBeenCalledWith("Error: General error")
 			expect(mockCline.diffViewProvider.reset).toHaveBeenCalled()
 		})