fix(task): accept response alias for attempt_completion result

Handle provider variance where attempt_completion sometimes emits `response` instead of `result`, and add regression coverage so we don't reintroduce missing-parameter failures.

Co-authored-by: Cursor <cursoragent@cursor.com>

.changeset/blue-points-sit.md

@@ -0,0 +1,5 @@
+---
+"cline": patch
+---
+
+Accept `response` as an alias for `attempt_completion`'s `result` parameter to handle provider output variance and prevent false missing-parameter errors.

src/core/task/tools/handlers/AttemptCompletionHandler.ts

@@ -19,6 +19,10 @@ import { ToolResultUtils } from "../utils/ToolResultUtils"
 
 const TASK_PREVIEW_MAX_CHARS = 8000
 
+function getCompletionResult(params: ToolUse["params"]): string | undefined {
+	return params.result || params.response
+}
+
 function getInitialTaskPreview(config: TaskConfig): string | undefined {
 	const firstTaskMessage = config.messageState
 		.getClineMessages()
@@ -44,7 +48,8 @@ export class AttemptCompletionHandler implements IToolHandler, IPartialBlockHand
 	 * Handle partial block streaming for attempt_completion
 	 */
 	async handlePartialBlock(block: ToolUse, uiHelpers: StronglyTypedUIHelpers): Promise<void> {
-		const result = uiHelpers.removeClosingTag(block, "result", block.params.result)
+		const rawResult = getCompletionResult(block.params)
+		const result = uiHelpers.removeClosingTag(block, "result", rawResult)
 		if (result) {
 			await uiHelpers.say("completion_result", result, undefined, undefined, block.partial)
 		}
@@ -52,7 +57,7 @@ export class AttemptCompletionHandler implements IToolHandler, IPartialBlockHand
 	}
 
 	async execute(config: TaskConfig, block: ToolUse): Promise<ToolResponse> {
-		const result: string | undefined = block.params.result
+		const result: string | undefined = getCompletionResult(block.params)
 		const command: string | undefined = block.params.command
 
 		// Validate required parameters
@@ -315,7 +320,7 @@ export class AttemptCompletionHandler implements IToolHandler, IPartialBlockHand
 						taskMetadata: {
 							taskId: config.taskId,
 							ulid: config.ulid,
-							result: block.params.result || "",
+							result: getCompletionResult(block.params) || "",
 							command: block.params.command || "",
 						},
 					},

src/core/task/tools/handlers/__tests__/AttemptCompletionHandler.resultAlias.test.ts

@@ -0,0 +1,69 @@
+import { strict as assert } from "node:assert"
+import { ClineDefaultTool } from "@shared/tools"
+import { describe, it } from "mocha"
+import sinon from "sinon"
+import { TaskState } from "../../../TaskState"
+import type { TaskConfig } from "../../types/TaskConfig"
+import { AttemptCompletionHandler } from "../AttemptCompletionHandler"
+
+function createConfig(options?: { doubleCheckEnabled?: boolean; pending?: boolean }) {
+	const taskState = new TaskState()
+	taskState.doubleCheckCompletionPending = options?.pending ?? false
+	taskState.consecutiveMistakeCount = 2
+
+	const callbacks = {
+		sayAndCreateMissingParamError: sinon.stub().resolves("missing-param"),
+		removeLastPartialMessageIfExistsWithType: sinon.stub().resolves(),
+	} as unknown as TaskConfig["callbacks"]
+
+	const config = {
+		taskId: "task-1",
+		ulid: "ulid-1",
+		taskState,
+		doubleCheckCompletionEnabled: options?.doubleCheckEnabled ?? false,
+		messageState: {
+			getClineMessages: () => [],
+		},
+		callbacks,
+	} as unknown as TaskConfig
+
+	return { config, callbacks, taskState }
+}
+
+describe("AttemptCompletionHandler result alias", () => {
+	it("accepts response as result for validation", async () => {
+		const { config, callbacks, taskState } = createConfig({ doubleCheckEnabled: true, pending: false })
+		const handler = new AttemptCompletionHandler()
+
+		const result = await handler.execute(config, {
+			type: "tool_use",
+			name: ClineDefaultTool.ATTEMPT,
+			params: {
+				response: "done via response alias",
+			},
+			partial: false,
+		})
+
+		assert.equal(taskState.consecutiveMistakeCount, 0)
+		assert.equal(taskState.doubleCheckCompletionPending, true)
+		sinon.assert.notCalled(callbacks.sayAndCreateMissingParamError as sinon.SinonStub)
+		assert.equal(typeof result, "string")
+		assert.ok((result as string).includes("Before completing"))
+	})
+
+	it("still errors when both result and response are missing", async () => {
+		const { config, callbacks, taskState } = createConfig()
+		const handler = new AttemptCompletionHandler()
+
+		const result = await handler.execute(config, {
+			type: "tool_use",
+			name: ClineDefaultTool.ATTEMPT,
+			params: {},
+			partial: false,
+		})
+
+		assert.equal(result, "missing-param")
+		assert.equal(taskState.consecutiveMistakeCount, 3)
+		sinon.assert.calledOnce(callbacks.sayAndCreateMissingParamError as sinon.SinonStub)
+	})
+})