fix(AttemptCompletionTool): child tasks return to parent when parent status is active (#510)

* chore: add subtask delegation diagnostics

* fix(AttempCompletionTool): allow completion of active parents

* test(subtasks): harness updates

Author: edelauna

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

@@ -5,10 +5,24 @@ import { toolResultContains } from "./tool-result"
 
 const SUBTASK_PARENT_MARKER = "SUBTASK_PARENT_CANCELLATION_SMOKE"
 const SUBTASK_CHILD_MARKER = "SUBTASK_CHILD_CALCULATOR_SMOKE"
+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"
+const SUBTASK_XPROFILE_SAME_CHILD_MARKER = "SUBTASK_CHILD_SAME_PROFILE"
+const SUBTASK_XPROFILE_DIFFERENT_CHILD_MARKER = "SUBTASK_CHILD_DIFFERENT_PROFILE"
 
 const SUBTASK_CHILD_PROMPT = `${SUBTASK_CHILD_MARKER}: Ask the user exactly this follow-up question: What is the square root of 81? After the user answers, complete with only the answer.`
 export const SUBTASK_PARENT_PROMPT = `${SUBTASK_PARENT_MARKER}: Use the new_task tool exactly once. Create an ask-mode subtask with this exact message: "${SUBTASK_CHILD_PROMPT}" Do not answer directly.`
 export const SUBTASK_CHILD_FOLLOWUP_ANSWER = "9"
+const SUBTASK_FAST_CHILD_PROMPT = `${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_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.`
+export const SUBTASK_XPROFILE_SAME_CHILD_RESULT = "Same-profile child completed"
+export const SUBTASK_XPROFILE_DIFFERENT_CHILD_RESULT = "Different-profile child completed"
+export const SUBTASK_XPROFILE_PARENT_RESULT = "Sequential cross-profile parent resumed"
 
 const requestContains = (req: ChatCompletionRequest, expected: string[]) => {
 	const rawRequest = JSON.stringify(req)
@@ -40,6 +54,55 @@ const completionAfterAnswer = (followupId: string, completionId: string) => ({
 })
 
 export function addSubtaskFixtures(mock: InstanceType<typeof LLMock>) {
+	mock.addFixture({
+		match: {
+			userMessage: new RegExp(SUBTASK_FAST_PARENT_MARKER),
+			sequenceIndex: 0,
+		},
+		response: {
+			toolCalls: [
+				{
+					name: "new_task",
+					arguments: JSON.stringify({
+						mode: "ask",
+						message: SUBTASK_FAST_CHILD_PROMPT,
+					}),
+					id: "call_subtasks_fast_parent_new_task_001",
+				},
+			],
+		},
+	})
+
+	mock.addFixture({
+		match: {
+			userMessage: new RegExp(SUBTASK_FAST_CHILD_MARKER),
+		},
+		response: {
+			toolCalls: [
+				{
+					name: "attempt_completion",
+					arguments: JSON.stringify({ result: "Fast child completed" }),
+					id: "call_subtasks_fast_child_completion_002",
+				},
+			],
+		},
+	})
+
+	mock.addFixture({
+		match: {
+			toolCallId: "call_subtasks_fast_parent_new_task_001",
+		},
+		response: {
+			toolCalls: [
+				{
+					name: "attempt_completion",
+					arguments: JSON.stringify({ result: "Fast parent resumed" }),
+					id: "call_subtasks_fast_parent_completion_003",
+				},
+			],
+		},
+	})
+
 	mock.addFixture({
 		match: {
 			userMessage: new RegExp(SUBTASK_PARENT_MARKER),
@@ -92,4 +155,95 @@ export function addSubtaskFixtures(mock: InstanceType<typeof LLMock>) {
 			],
 		},
 	})
+
+	// Issue #457 sequence: a same-profile child returns first, then the resumed
+	// parent delegates to a child whose mode uses a different API profile.
+	mock.addFixture({
+		match: {
+			userMessage: new RegExp(SUBTASK_XPROFILE_PARENT_MARKER),
+			sequenceIndex: 0,
+		},
+		response: {
+			toolCalls: [
+				{
+					name: "new_task",
+					arguments: JSON.stringify({
+						mode: "code",
+						message: SUBTASK_XPROFILE_SAME_CHILD_PROMPT,
+					}),
+					id: "call_subtasks_xprofile_parent_same_child_001",
+				},
+			],
+		},
+	})
+
+	mock.addFixture({
+		match: {
+			userMessage: new RegExp(SUBTASK_XPROFILE_SAME_CHILD_MARKER),
+		},
+		response: {
+			toolCalls: [
+				{
+					name: "attempt_completion",
+					arguments: JSON.stringify({ result: SUBTASK_XPROFILE_SAME_CHILD_RESULT }),
+					id: "call_subtasks_xprofile_same_child_completion_002",
+				},
+			],
+		},
+	})
+
+	mock.addFixture({
+		match: {
+			predicate: (req: ChatCompletionRequest) =>
+				requestContains(req, [SUBTASK_XPROFILE_PARENT_MARKER, SUBTASK_XPROFILE_SAME_CHILD_RESULT]) &&
+				!requestContains(req, [SUBTASK_XPROFILE_DIFFERENT_CHILD_RESULT]),
+		},
+		response: {
+			toolCalls: [
+				{
+					name: "new_task",
+					arguments: JSON.stringify({
+						mode: "ask",
+						message: SUBTASK_XPROFILE_DIFFERENT_CHILD_PROMPT,
+					}),
+					id: "call_subtasks_xprofile_parent_different_child_003",
+				},
+			],
+		},
+	})
+
+	mock.addFixture({
+		match: {
+			userMessage: new RegExp(SUBTASK_XPROFILE_DIFFERENT_CHILD_MARKER),
+		},
+		response: {
+			toolCalls: [
+				{
+					name: "attempt_completion",
+					arguments: JSON.stringify({ result: SUBTASK_XPROFILE_DIFFERENT_CHILD_RESULT }),
+					id: "call_subtasks_xprofile_different_child_completion_004",
+				},
+			],
+		},
+	})
+
+	mock.addFixture({
+		match: {
+			predicate: (req: ChatCompletionRequest) =>
+				requestContains(req, [
+					SUBTASK_XPROFILE_PARENT_MARKER,
+					SUBTASK_XPROFILE_SAME_CHILD_RESULT,
+					SUBTASK_XPROFILE_DIFFERENT_CHILD_RESULT,
+				]),
+		},
+		response: {
+			toolCalls: [
+				{
+					name: "attempt_completion",
+					arguments: JSON.stringify({ result: SUBTASK_XPROFILE_PARENT_RESULT }),
+					id: "call_subtasks_xprofile_parent_completion_005",
+				},
+			],
+		},
+	})
 }