fix(task-lifecycle): preserve parent-child link when delegated subtask is interrupted (#560)

apps/cli/src/ui/components/autocomplete/triggers/HistoryTrigger.tsx

@@ -21,7 +21,7 @@ export interface HistoryResult extends AutocompleteItem {
 	/** Mode the task was run in */
 	mode?: string
 	/** Task status */
-	status?: "active" | "completed" | "delegated"
+	status?: "active" | "completed" | "delegated" | "interrupted"
 }
 
 /**
@@ -133,8 +133,22 @@ export function createHistoryTrigger(config: HistoryTriggerConfig): Autocomplete
 
 		renderItem: (item: HistoryResult, isSelected: boolean) => {
 			// Status indicator
-			const statusIcon = item.status === "completed" ? "✓" : item.status === "active" ? "●" : "○"
-			const statusColor = item.status === "completed" ? "green" : item.status === "active" ? "yellow" : "gray"
+			const statusIcon =
+				item.status === "completed"
+					? "✓"
+					: item.status === "active"
+						? "●"
+						: item.status === "interrupted"
+							? "⏸"
+							: "○"
+			const statusColor =
+				item.status === "completed"
+					? "green"
+					: item.status === "active"
+						? "yellow"
+						: item.status === "interrupted"
+							? "cyan"
+							: "gray"
 
 			// Mode indicator (if available)
 			const modeText = item.mode ? ` [${item.mode}]` : ""
@@ -178,7 +192,7 @@ export function toHistoryResult(item: {
 	totalCost?: number
 	workspace?: string
 	mode?: string
-	status?: "active" | "completed" | "delegated"
+	status?: "active" | "completed" | "delegated" | "interrupted"
 }): HistoryResult {
 	return {
 		key: item.id, // Use task ID as the unique key

apps/cli/src/ui/components/autocomplete/triggers/__tests__/HistoryTrigger.test.tsx

@@ -188,6 +188,24 @@ describe("HistoryTrigger", () => {
 			expect(output).toContain("○")
 		})
 
+		it("should render interrupted status with correct indicator", () => {
+			const trigger = createHistoryTrigger({ getHistory: () => mockHistoryItems })
+
+			const interruptedItem: HistoryResult = {
+				key: "task-interrupted",
+				id: "task-interrupted",
+				task: "Interrupted subtask waiting to resume",
+				ts: Date.now() - 1000 * 60 * 5,
+				mode: "ask",
+				status: "interrupted",
+			}
+			const { lastFrame } = render(trigger.renderItem(interruptedItem, false) as React.ReactElement)
+
+			const output = lastFrame()
+			// Should contain the interrupted status indicator (⏸)
+			expect(output).toContain("⏸")
+		})
+
 		it("should render selected items with different styling", () => {
 			const trigger = createHistoryTrigger({ getHistory: () => mockHistoryItems })
 

apps/cli/src/ui/types.ts

@@ -109,7 +109,7 @@ export interface TaskHistoryItem {
 	totalCost?: number
 	workspace?: string
 	mode?: string
-	status?: "active" | "completed" | "delegated"
+	status?: "active" | "completed" | "delegated" | "interrupted"
 	tokensIn?: number
 	tokensOut?: number
 }

apps/vscode-e2e/src/fixtures/subtasks.ts

@@ -5,6 +5,8 @@ import { toolResultContains } from "./tool-result"
 
 const SUBTASK_PARENT_MARKER = "SUBTASK_PARENT_CANCELLATION_SMOKE"
 const SUBTASK_CHILD_MARKER = "SUBTASK_CHILD_CALCULATOR_SMOKE"
+const SUBTASK_INTERRUPT_PARENT_MARKER = "SUBTASK_PARENT_INTERRUPT_RESUME"
+const SUBTASK_INTERRUPT_CHILD_MARKER = "SUBTASK_CHILD_INTERRUPT_RESUME"
 const SUBTASK_FAST_PARENT_MARKER = "SUBTASK_PARENT_IMMEDIATE_COMPLETION"
 const SUBTASK_FAST_CHILD_MARKER = "SUBTASK_CHILD_IMMEDIATE_COMPLETION"
 const SUBTASK_XPROFILE_PARENT_MARKER = "SUBTASK_PARENT_CROSS_PROFILE"
@@ -17,6 +19,11 @@ export const SUBTASK_CHILD_FOLLOWUP_ANSWER = "9"
 const SUBTASK_FAST_CHILD_PROMPT = `${SUBTASK_FAST_CHILD_MARKER}: Complete immediately with the exact result "Fast child completed".`
 export const SUBTASK_FAST_PARENT_PROMPT = `${SUBTASK_FAST_PARENT_MARKER}: Use the new_task tool exactly once. Create an ask-mode subtask with this exact message: "${SUBTASK_FAST_CHILD_PROMPT}" Do not answer directly.`
 
+const SUBTASK_INTERRUPT_CHILD_PROMPT = `${SUBTASK_INTERRUPT_CHILD_MARKER}: Ask the user exactly this follow-up question: What is the square root of 81? After the user answers, complete with only the answer.`
+export const SUBTASK_INTERRUPT_PARENT_PROMPT = `${SUBTASK_INTERRUPT_PARENT_MARKER}: Use the new_task tool exactly once. Create an ask-mode subtask with this exact message: "${SUBTASK_INTERRUPT_CHILD_PROMPT}" Do not answer directly. When the subtask returns, complete with the exact result "Interrupted parent resumed".`
+export const SUBTASK_INTERRUPT_CHILD_FOLLOWUP_ANSWER = "9"
+export const SUBTASK_INTERRUPT_PARENT_RESULT = "Interrupted parent resumed"
+
 const SUBTASK_XPROFILE_SAME_CHILD_PROMPT = `${SUBTASK_XPROFILE_SAME_CHILD_MARKER}: Complete immediately with the exact result "Same-profile child completed".`
 const SUBTASK_XPROFILE_DIFFERENT_CHILD_PROMPT = `${SUBTASK_XPROFILE_DIFFERENT_CHILD_MARKER}: Complete immediately with the exact result "Different-profile child completed".`
 export const SUBTASK_XPROFILE_PARENT_PROMPT = `${SUBTASK_XPROFILE_PARENT_MARKER}: First use new_task to create a code-mode subtask with this exact message: "${SUBTASK_XPROFILE_SAME_CHILD_PROMPT}" After it returns, create an ask-mode subtask with the next instructions you receive.`
@@ -32,15 +39,17 @@ const requestContains = (req: ChatCompletionRequest, expected: string[]) => {
 const completionAfterAnswer = (followupId: string, completionId: string) => ({
 	match: {
 		predicate: (req: ChatCompletionRequest) =>
+			!requestContains(req, [SUBTASK_INTERRUPT_CHILD_MARKER]) &&
+			!requestContains(req, [SUBTASK_INTERRUPT_PARENT_MARKER]) &&
 			// Preferred: structured tool-result message carries the followup answer.
-			toolResultContains(req, followupId, [SUBTASK_CHILD_FOLLOWUP_ANSWER]) ||
-			// Fallback 1: answer present alongside the tool-call ID but not in a role:tool message.
-			requestContains(req, [followupId, SUBTASK_CHILD_FOLLOWUP_ANSWER]) ||
-			// Fallback 2: answer arrives as a bare user message after task resume (no tool-call ID context).
-			requestContains(req, [
-				SUBTASK_CHILD_MARKER,
-				`<user_message>\\n${SUBTASK_CHILD_FOLLOWUP_ANSWER}\\n</user_message>`,
-			]),
+			(toolResultContains(req, followupId, [SUBTASK_CHILD_FOLLOWUP_ANSWER]) ||
+				// Fallback 1: answer present alongside the tool-call ID but not in a role:tool message.
+				requestContains(req, [followupId, SUBTASK_CHILD_FOLLOWUP_ANSWER]) ||
+				// Fallback 2: answer arrives as a bare user message after task resume (no tool-call ID context).
+				requestContains(req, [
+					SUBTASK_CHILD_MARKER,
+					`<user_message>\\n${SUBTASK_CHILD_FOLLOWUP_ANSWER}\\n</user_message>`,
+				])),
 	},
 	response: {
 		toolCalls: [
@@ -90,7 +99,8 @@ export function addSubtaskFixtures(mock: InstanceType<typeof LLMock>) {
 
 	mock.addFixture({
 		match: {
-			toolCallId: "call_subtasks_fast_parent_new_task_001",
+			predicate: (req: ChatCompletionRequest) =>
+				requestContains(req, [SUBTASK_FAST_PARENT_MARKER, "call_subtasks_fast_parent_new_task_001"]),
 		},
 		response: {
 			toolCalls: [
@@ -143,7 +153,8 @@ export function addSubtaskFixtures(mock: InstanceType<typeof LLMock>) {
 
 	mock.addFixture({
 		match: {
-			toolCallId: "call_subtasks_parent_new_task_001",
+			predicate: (req: ChatCompletionRequest) =>
+				requestContains(req, [SUBTASK_PARENT_MARKER, "call_subtasks_parent_new_task_001"]),
 		},
 		response: {
 			toolCalls: [
@@ -252,4 +263,95 @@ export function addSubtaskFixtures(mock: InstanceType<typeof LLMock>) {
 			],
 		},
 	})
+
+	// Interrupted-child-resumes-and-reports-back scenario (#560)
+	mock.addFixture({
+		match: {
+			userMessage: new RegExp(SUBTASK_INTERRUPT_PARENT_MARKER),
+			sequenceIndex: 0,
+		},
+		response: {
+			toolCalls: [
+				{
+					name: "new_task",
+					arguments: JSON.stringify({
+						mode: "ask",
+						message: SUBTASK_INTERRUPT_CHILD_PROMPT,
+					}),
+					id: "call_interrupt_parent_new_task_001",
+				},
+			],
+		},
+	})
+
+	// The parent prompt embeds SUBTASK_INTERRUPT_CHILD_MARKER verbatim, so parent-resume turns
+	// also match a bare substring check. Exclude the parent marker so they fall through.
+	// The answer exclusion must use the <user_message> wrapping: the bare answer is a single
+	// digit that can appear anywhere in the serialized request (timestamps in environment
+	// details, token counts), which would make this fixture unmatchable.
+	mock.addFixture({
+		match: {
+			predicate: (req: ChatCompletionRequest) =>
+				requestContains(req, [SUBTASK_INTERRUPT_CHILD_MARKER]) &&
+				!requestContains(req, [SUBTASK_INTERRUPT_PARENT_MARKER]) &&
+				!requestContains(req, ["call_interrupt_child_followup_001"]) &&
+				!requestContains(req, [
+					`<user_message>\\n${SUBTASK_INTERRUPT_CHILD_FOLLOWUP_ANSWER}\\n</user_message>`,
+				]),
+		},
+		response: {
+			toolCalls: [
+				{
+					name: "ask_followup_question",
+					arguments: JSON.stringify({
+						question: "What is the square root of 81?",
+						follow_up: [{ text: SUBTASK_INTERRUPT_CHILD_FOLLOWUP_ANSWER }],
+					}),
+					id: "call_interrupt_child_followup_001",
+				},
+			],
+		},
+	})
+
+	mock.addFixture({
+		match: {
+			predicate: (req: ChatCompletionRequest) =>
+				// Preferred: structured tool-result message carries the followup answer.
+				toolResultContains(req, "call_interrupt_child_followup_001", [
+					SUBTASK_INTERRUPT_CHILD_FOLLOWUP_ANSWER,
+				]) ||
+				// Fallback 1: answer present alongside the tool-call ID.
+				requestContains(req, ["call_interrupt_child_followup_001", SUBTASK_INTERRUPT_CHILD_FOLLOWUP_ANSWER]) ||
+				// Fallback 2: answer arrives as a bare user message after task resume.
+				requestContains(req, [
+					SUBTASK_INTERRUPT_CHILD_MARKER,
+					`<user_message>\\n${SUBTASK_INTERRUPT_CHILD_FOLLOWUP_ANSWER}\\n</user_message>`,
+				]),
+		},
+		response: {
+			toolCalls: [
+				{
+					name: "attempt_completion",
+					arguments: JSON.stringify({ result: "9" }),
+					id: "call_interrupt_child_completion_002",
+				},
+			],
+		},
+	})
+
+	mock.addFixture({
+		match: {
+			predicate: (req: ChatCompletionRequest) =>
+				requestContains(req, [SUBTASK_INTERRUPT_PARENT_MARKER, "call_interrupt_parent_new_task_001"]),
+		},
+		response: {
+			toolCalls: [
+				{
+					name: "attempt_completion",
+					arguments: JSON.stringify({ result: "Interrupted parent resumed" }),
+					id: "call_interrupt_parent_completion_003",
+				},
+			],
+		},
+	})
 }