Fix #4888: Finalize pending api_req_started messages on task completion

- Add finish() method to Task class that finds all api_req_started messages
  without cost or cancelReason and sets their cost to 0
- Call finish() before emitting taskCompleted in attemptCompletionTool
- Add comprehensive tests for the finish() method
- Prevents UI spinners from persisting in completed task history

src/core/task/Task.ts

@@ -1908,6 +1908,39 @@ export class Task extends EventEmitter<ClineEvents> {
 		}
 	}
 
+	// Task completion
+
+	public async finish() {
+		// Find any api_req_started messages that are still pending (no cost and no cancelReason)
+		// While theoretically only the last one should be unfinished, the UI checks all messages
+		const messages = [...this.clineMessages]
+		let hasUpdates = false
+
+		for (let i = 0; i < messages.length; i++) {
+			const message = messages[i]
+			if (message.type === "say" && message.say === "api_req_started") {
+				const apiReqInfo: ClineApiReqInfo = JSON.parse(message.text || "{}")
+
+				// Check if this message is still pending (no cost and no cancelReason)
+				if (apiReqInfo.cost === undefined && apiReqInfo.cancelReason === undefined) {
+					// Update the message to have a cost of 0 to indicate completion
+					apiReqInfo.cost = 0
+					messages[i] = {
+						...message,
+						text: JSON.stringify(apiReqInfo),
+					}
+					hasUpdates = true
+				}
+			}
+		}
+
+		// Save the updated messages if any were modified
+		if (hasUpdates) {
+			this.clineMessages = messages
+			await this.saveClineMessages()
+		}
+	}
+
 	// Getters
 
 	public get cwd() {

src/core/task/__tests__/Task.spec.ts

@@ -1334,5 +1334,184 @@ describe("Cline", () => {
 				expect(task.diffStrategy).toBeUndefined()
 			})
 		})
+
+		describe("finish method", () => {
+			it("should finalize all pending api_req_started messages with cost 0", async () => {
+				const [cline, task] = Task.create({
+					provider: mockProvider,
+					apiConfiguration: mockApiConfig,
+					task: "test task",
+				})
+
+				// Mock saveClineMessages
+				const saveSpy = vi.spyOn(cline as any, "saveClineMessages").mockResolvedValue(undefined)
+
+				// Set up messages with multiple api_req_started messages
+				cline.clineMessages = [
+					{
+						ts: Date.now(),
+						type: "say",
+						say: "text",
+						text: "Regular message",
+					},
+					{
+						ts: Date.now(),
+						type: "say",
+						say: "api_req_started",
+						text: JSON.stringify({
+							request: "test request 1",
+							tokensIn: 100,
+							tokensOut: 50,
+							// No cost - should be updated
+						}),
+					},
+					{
+						ts: Date.now(),
+						type: "say",
+						say: "api_req_started",
+						text: JSON.stringify({
+							request: "test request 2",
+							tokensIn: 200,
+							tokensOut: 100,
+							cost: 0.001, // Already has cost
+						}),
+					},
+					{
+						ts: Date.now(),
+						type: "say",
+						say: "text",
+						text: "Another regular message",
+					},
+					{
+						ts: Date.now(),
+						type: "say",
+						say: "api_req_started",
+						text: JSON.stringify({
+							request: "test request 3",
+							tokensIn: 300,
+							tokensOut: 150,
+							// No cost or cancelReason - should be updated
+						}),
+					},
+				]
+
+				// Call finish
+				await cline.finish()
+
+				// Verify saveClineMessages was called
+				expect(saveSpy).toHaveBeenCalled()
+
+				// Verify the messages were updated correctly
+				const messages = cline.clineMessages
+
+				// First api_req_started (index 1) had no cost, should now have cost 0
+				const msg1 = JSON.parse(messages[1].text || "{}")
+				expect(msg1.cost).toBe(0)
+				expect(msg1.request).toBe("test request 1")
+
+				// Second api_req_started (index 2) already had cost, should be unchanged
+				const msg2 = JSON.parse(messages[2].text || "{}")
+				expect(msg2.cost).toBe(0.001)
+
+				// Last api_req_started (index 4) had no cost/cancelReason, should now have cost 0
+				const msg3 = JSON.parse(messages[4].text || "{}")
+				expect(msg3.cost).toBe(0)
+				expect(msg3.request).toBe("test request 3")
+
+				// Verify that ALL api_req_started messages now have either cost or cancelReason
+				const apiReqMessages = messages.filter((m) => m.type === "say" && m.say === "api_req_started")
+				for (const msg of apiReqMessages) {
+					const apiReqInfo = JSON.parse(msg.text || "{}")
+					const hasCost = apiReqInfo.cost !== undefined
+					const hasCancelReason = apiReqInfo.cancelReason !== undefined
+					expect(hasCost || hasCancelReason).toBe(true)
+				}
+
+				await cline.abortTask(true)
+				await task.catch(() => {})
+			})
+
+			it("should not save if no api_req_started messages need updating", async () => {
+				const [cline, task] = Task.create({
+					provider: mockProvider,
+					apiConfiguration: mockApiConfig,
+					task: "test task",
+				})
+
+				// Mock saveClineMessages
+				const saveSpy = vi.spyOn(cline as any, "saveClineMessages").mockResolvedValue(undefined)
+
+				// Set up messages where all api_req_started already have cost or cancelReason
+				cline.clineMessages = [
+					{
+						ts: Date.now(),
+						type: "say",
+						say: "api_req_started",
+						text: JSON.stringify({
+							request: "test request 1",
+							tokensIn: 100,
+							tokensOut: 50,
+							cost: 0.001, // Has cost
+						}),
+					},
+					{
+						ts: Date.now(),
+						type: "say",
+						say: "api_req_started",
+						text: JSON.stringify({
+							request: "test request 2",
+							tokensIn: 200,
+							tokensOut: 100,
+							cancelReason: "User cancelled", // Has cancelReason
+						}),
+					},
+				]
+
+				// Clear any calls from setup
+				saveSpy.mockClear()
+
+				// Call finish
+				await cline.finish()
+
+				// Verify saveClineMessages was NOT called since no updates were needed
+				expect(saveSpy).not.toHaveBeenCalled()
+
+				await cline.abortTask(true)
+				await task.catch(() => {})
+			})
+
+			it("should handle case with no api_req_started messages", async () => {
+				const [cline, task] = Task.create({
+					provider: mockProvider,
+					apiConfiguration: mockApiConfig,
+					task: "test task",
+				})
+
+				// Mock saveClineMessages
+				const saveSpy = vi.spyOn(cline as any, "saveClineMessages").mockResolvedValue(undefined)
+
+				// Set up messages with no api_req_started
+				cline.clineMessages = [
+					{
+						ts: Date.now(),
+						type: "say",
+						say: "text",
+						text: "Just a regular message",
+					},
+				]
+
+				// Clear any calls from setup
+				saveSpy.mockClear()
+
+				// Call finish
+				await cline.finish()
+
+				// Verify saveClineMessages was NOT called
+				expect(saveSpy).not.toHaveBeenCalled()
+
+				await cline.abortTask(true)
+				await task.catch(() => {})
+			})
+		})
 	})
 })

src/core/tools/attemptCompletionTool.ts

@@ -45,6 +45,7 @@ export async function attemptCompletionTool(
 					// we have command string, which means we have the result as well, so finish it (doesnt have to exist yet)
 					await cline.say("completion_result", removeClosingTag("result", result), undefined, false)
 
+					await cline.finish()
 					TelemetryService.instance.captureTaskCompleted(cline.taskId)
 					cline.emit("taskCompleted", cline.taskId, cline.getTokenUsage(), cline.toolUsage)
 
@@ -68,6 +69,7 @@ export async function attemptCompletionTool(
 			// Command execution is permanently disabled in attempt_completion
 			// Users must use execute_command tool separately before attempt_completion
 			await cline.say("completion_result", result, undefined, false)
+			await cline.finish()
 			TelemetryService.instance.captureTaskCompleted(cline.taskId)
 			cline.emit("taskCompleted", cline.taskId, cline.getTokenUsage(), cline.toolUsage)