fix: preserve subtask metadata when AI returns modified subtasks

- Add subtask metadata preservation in FileStorage.updateTask
- Add subtask metadata preservation in legacy update-task-by-id.js
- Add test for subtask metadata preservation during AI updates

Fixes Cursor Bugbot review comment about subtask metadata loss

packages/tm-core/src/modules/storage/adapters/file-storage/file-storage.ts

@@ -381,9 +381,28 @@ export class FileStorage implements IStorage {
 			throw new Error(`Task ${taskId} not found`);
 		}
 
+		const existingTask = tasks[taskIndex];
+
+		// Preserve subtask metadata when subtasks are updated
+		// AI operations don't include metadata in returned subtasks
+		let mergedSubtasks = updates.subtasks;
+		if (updates.subtasks && existingTask.subtasks) {
+			mergedSubtasks = updates.subtasks.map((updatedSubtask) => {
+				const originalSubtask = existingTask.subtasks?.find(
+					(st) => st.id === updatedSubtask.id
+				);
+				// Preserve original subtask's metadata if it exists
+				if (originalSubtask?.metadata) {
+					return { ...updatedSubtask, metadata: originalSubtask.metadata };
+				}
+				return updatedSubtask;
+			});
+		}
+
 		tasks[taskIndex] = {
-			...tasks[taskIndex],
+			...existingTask,
 			...updates,
+			...(mergedSubtasks && { subtasks: mergedSubtasks }),
 			id: String(taskId) // Keep consistent with normalizeTaskIds
 		};
 		await this.saveTasks(tasks, tag);

packages/tm-core/tests/integration/ai-operations/metadata-preservation.test.ts

@@ -272,6 +272,90 @@ describe('AI Operation Metadata Preservation - Integration Tests', () => {
 				subtaskMeta: 'subtask-value'
 			});
 		});
+
+		it('should preserve subtask metadata when AI returns modified subtasks', async () => {
+			// This tests the scenario where update-task AI returns subtasks
+			// (full update mode, not append mode) - subtask metadata must be preserved
+			const tasks: Task[] = [
+				createTask('1', {
+					metadata: { parentMeta: 'parent-value' },
+					subtasks: [
+						{
+							id: 1,
+							parentId: '1',
+							title: 'Original subtask 1',
+							description: 'Has metadata',
+							status: 'pending',
+							priority: 'medium',
+							dependencies: [],
+							details: '',
+							testStrategy: '',
+							metadata: { ticket: 'JIRA-100', sprint: 'S1' }
+						},
+						{
+							id: 2,
+							parentId: '1',
+							title: 'Original subtask 2',
+							description: 'Also has metadata',
+							status: 'in-progress',
+							priority: 'high',
+							dependencies: [1],
+							details: '',
+							testStrategy: '',
+							metadata: { ticket: 'JIRA-101', reviewed: true }
+						}
+					]
+				})
+			];
+			await storage.saveTasks(tasks);
+
+			// Simulate AI returning modified subtasks (AI doesn't include metadata)
+			const aiModifiedSubtasks = [
+				{
+					id: 1,
+					parentId: '1',
+					title: 'AI updated subtask 1', // Title changed by AI
+					description: 'AI updated description',
+					status: 'pending',
+					priority: 'medium',
+					dependencies: [],
+					details: 'AI added details',
+					testStrategy: ''
+					// No metadata - AI schema excludes it
+				},
+				{
+					id: 2,
+					parentId: '1',
+					title: 'AI updated subtask 2',
+					description: 'AI updated this too',
+					status: 'in-progress',
+					priority: 'high',
+					dependencies: [1],
+					details: 'More AI details',
+					testStrategy: ''
+					// No metadata - AI schema excludes it
+				}
+			];
+
+			// Update task with AI-modified subtasks
+			await storage.updateTask('1', {
+				title: 'AI Updated Task',
+				subtasks: aiModifiedSubtasks
+			});
+
+			const loadedTasks = await storage.loadTasks();
+			// Parent metadata preserved
+			expect(loadedTasks[0].metadata).toEqual({ parentMeta: 'parent-value' });
+			// Subtask metadata should be preserved from originals
+			expect(loadedTasks[0].subtasks[0].metadata).toEqual({
+				ticket: 'JIRA-100',
+				sprint: 'S1'
+			});
+			expect(loadedTasks[0].subtasks[1].metadata).toEqual({
+				ticket: 'JIRA-101',
+				reviewed: true
+			});
+		});
 	});
 
 	describe('parse-prd operation simulation', () => {

scripts/modules/task-manager/update-task-by-id.js

@@ -455,6 +455,10 @@ async function updateTaskById(
 			if (updatedTask.subtasks && Array.isArray(updatedTask.subtasks)) {
 				let currentSubtaskId = 1;
 				updatedTask.subtasks = updatedTask.subtasks.map((subtask) => {
+					// Find original subtask to preserve its metadata
+					const originalSubtask = taskToUpdate.subtasks?.find(
+						(st) => st.id === subtask.id || st.id === currentSubtaskId
+					);
 					// Fix AI-generated subtask IDs that might be strings or use parent ID as prefix
 					const correctedSubtask = {
 						...subtask,
@@ -472,8 +476,11 @@ async function updateTaskById(
 									)
 							: [],
 						status: subtask.status || 'pending',
-						testStrategy: subtask.testStrategy ?? null
-					};
+					testStrategy: subtask.testStrategy ?? null,
+					// Preserve subtask metadata from original (AI schema excludes metadata)
+					...(originalSubtask?.metadata && {
+						metadata: originalSubtask.metadata
+					})					};
 					currentSubtaskId++;
 					return correctedSubtask;
 				});