fix: resolve phantom subtask display on cancel during API retry (#4602) (#4893)

Author: hannesrudolph

src/core/webview/ClineProvider.ts

@@ -232,6 +232,12 @@ export class ClineProvider
 		await this.getCurrentCline()?.resumePausedTask(lastMessage)
 	}
 
+	// Clear the current task without treating it as a subtask
+	// This is used when the user cancels a task that is not a subtask
+	async clearTask() {
+		await this.removeClineFromStack()
+	}
+
 	/*
 	VSCode extensions use the disposable pattern to clean up resources when the sidebar/editor tab is closed by the user or system. This applies to event listening, commands, interacting with the UI, etc.
 	- https://vscode-docs.readthedocs.io/en/stable/extensions/patterns-and-principles/

src/core/webview/__tests__/ClineProvider.spec.ts

@@ -569,6 +569,117 @@ describe("ClineProvider", () => {
 		expect(stackSizeBeforeAbort - stackSizeAfterAbort).toBe(1)
 	})
 
+	describe("clearTask message handler", () => {
+		beforeEach(async () => {
+			await provider.resolveWebviewView(mockWebviewView)
+		})
+
+		test("calls clearTask when there is no parent task", async () => {
+			// Setup a single task without parent
+			const mockCline = new Task(defaultTaskOptions)
+			// No need to set parentTask - it's undefined by default
+
+			// Mock the provider methods
+			const clearTaskSpy = vi.spyOn(provider, "clearTask").mockResolvedValue(undefined)
+			const finishSubTaskSpy = vi.spyOn(provider, "finishSubTask").mockResolvedValue(undefined)
+			const postStateToWebviewSpy = vi.spyOn(provider, "postStateToWebview").mockResolvedValue(undefined)
+
+			// Add task to stack
+			await provider.addClineToStack(mockCline)
+
+			// Get the message handler
+			const messageHandler = (mockWebviewView.webview.onDidReceiveMessage as any).mock.calls[0][0]
+
+			// Trigger clearTask message
+			await messageHandler({ type: "clearTask" })
+
+			// Verify clearTask was called (not finishSubTask)
+			expect(clearTaskSpy).toHaveBeenCalled()
+			expect(finishSubTaskSpy).not.toHaveBeenCalled()
+			expect(postStateToWebviewSpy).toHaveBeenCalled()
+		})
+
+		test("calls finishSubTask when there is a parent task", async () => {
+			// Setup parent and child tasks
+			const parentTask = new Task(defaultTaskOptions)
+			const childTask = new Task(defaultTaskOptions)
+
+			// Set up parent-child relationship by setting the parentTask property
+			// The mock allows us to set properties directly
+			;(childTask as any).parentTask = parentTask
+			;(childTask as any).rootTask = parentTask
+
+			// Mock the provider methods
+			const clearTaskSpy = vi.spyOn(provider, "clearTask").mockResolvedValue(undefined)
+			const finishSubTaskSpy = vi.spyOn(provider, "finishSubTask").mockResolvedValue(undefined)
+			const postStateToWebviewSpy = vi.spyOn(provider, "postStateToWebview").mockResolvedValue(undefined)
+
+			// Add both tasks to stack (parent first, then child)
+			await provider.addClineToStack(parentTask)
+			await provider.addClineToStack(childTask)
+
+			// Get the message handler
+			const messageHandler = (mockWebviewView.webview.onDidReceiveMessage as any).mock.calls[0][0]
+
+			// Trigger clearTask message
+			await messageHandler({ type: "clearTask" })
+
+			// Verify finishSubTask was called (not clearTask)
+			expect(finishSubTaskSpy).toHaveBeenCalledWith(expect.stringContaining("canceled"))
+			expect(clearTaskSpy).not.toHaveBeenCalled()
+			expect(postStateToWebviewSpy).toHaveBeenCalled()
+		})
+
+		test("handles case when no current task exists", async () => {
+			// Don't add any tasks to the stack
+
+			// Mock the provider methods
+			const clearTaskSpy = vi.spyOn(provider, "clearTask").mockResolvedValue(undefined)
+			const finishSubTaskSpy = vi.spyOn(provider, "finishSubTask").mockResolvedValue(undefined)
+			const postStateToWebviewSpy = vi.spyOn(provider, "postStateToWebview").mockResolvedValue(undefined)
+
+			// Get the message handler
+			const messageHandler = (mockWebviewView.webview.onDidReceiveMessage as any).mock.calls[0][0]
+
+			// Trigger clearTask message
+			await messageHandler({ type: "clearTask" })
+
+			// When there's no current task, clearTask is still called (it handles the no-task case internally)
+			expect(clearTaskSpy).toHaveBeenCalled()
+			expect(finishSubTaskSpy).not.toHaveBeenCalled()
+			// State should still be posted
+			expect(postStateToWebviewSpy).toHaveBeenCalled()
+		})
+
+		test("correctly identifies subtask scenario for issue #4602", async () => {
+			// This test specifically validates the fix for issue #4602
+			// where canceling during API retry was incorrectly treating a single task as a subtask
+
+			const mockCline = new Task(defaultTaskOptions)
+			// No parent task by default - no need to explicitly set
+
+			// Mock the provider methods
+			const clearTaskSpy = vi.spyOn(provider, "clearTask").mockResolvedValue(undefined)
+			const finishSubTaskSpy = vi.spyOn(provider, "finishSubTask").mockResolvedValue(undefined)
+
+			// Add only one task to stack
+			await provider.addClineToStack(mockCline)
+
+			// Verify stack size is 1
+			expect(provider.getClineStackSize()).toBe(1)
+
+			// Get the message handler
+			const messageHandler = (mockWebviewView.webview.onDidReceiveMessage as any).mock.calls[0][0]
+
+			// Trigger clearTask message (simulating cancel during API retry)
+			await messageHandler({ type: "clearTask" })
+
+			// The fix ensures clearTask is called, not finishSubTask
+			expect(clearTaskSpy).toHaveBeenCalled()
+			expect(finishSubTaskSpy).not.toHaveBeenCalled()
+		})
+	})
+
 	test("addClineToStack adds multiple Cline instances to the stack", async () => {
 		// Setup Cline instance with auto-mock from the top of the file
 		const mockCline1 = new Task(defaultTaskOptions) // Create a new mocked instance

src/core/webview/webviewMessageHandler.ts

@@ -201,7 +201,14 @@ export const webviewMessageHandler = async (
 			break
 		case "clearTask":
 			// clear task resets the current session and allows for a new task to be started, if this session is a subtask - it allows the parent task to be resumed
-			await provider.finishSubTask(t("common:tasks.canceled"))
+			// Check if the current task actually has a parent task
+			const currentTask = provider.getCurrentCline()
+			if (currentTask && currentTask.parentTask) {
+				await provider.finishSubTask(t("common:tasks.canceled"))
+			} else {
+				// Regular task - just clear it
+				await provider.clearTask()
+			}
 			await provider.postStateToWebview()
 			break
 		case "didShowAnnouncement":