fix: restore parent task references for subtasks after VS Code restart

When VS Code is closed during a subtask execution and then restarted, the subtask now properly restores its parent task reference from the persisted history. This ensures that when the subtask completes, it can report its final state back to the parent task.

The implementation:
- Restores parent task reference from history when resuming a subtask
- Recursively restores parent tasks if they are not already in the task stack
- Maintains the parent-child relationship across VS Code sessions
- Ensures subtask completion properly reports back to parent after restart

Fixes #9038

Author: roomote

src/core/webview/ClineProvider.ts

@@ -857,7 +857,9 @@ export class ClineProvider
 		await this.removeClineFromStack()
 	}
 
-	public async createTaskWithHistoryItem(historyItem: HistoryItem & { rootTask?: Task; parentTask?: Task }) {
+	public async createTaskWithHistoryItem(
+		historyItem: HistoryItem & { rootTask?: Task; parentTask?: Task },
+	): Promise<Task> {
 		await this.removeClineFromStack()
 
 		// If the history item has a saved mode, restore it and its associated API configuration.
@@ -903,6 +905,40 @@ export class ClineProvider
 			}
 		}
 
+		// Restore parent-child task relationships if this is a subtask
+		let restoredParentTask: Task | undefined = undefined
+		let restoredRootTask: Task | undefined = undefined
+
+		if (historyItem.parentTaskId) {
+			// Try to find the parent task in the current task stack
+			restoredParentTask = this.clineStack.find((task) => task.taskId === historyItem.parentTaskId)
+
+			if (!restoredParentTask) {
+				// Parent task is not in the stack, try to restore it from history
+				this.log(`Restoring parent task ${historyItem.parentTaskId} for subtask ${historyItem.id}`)
+				try {
+					const { historyItem: parentHistoryItem } = await this.getTaskWithId(historyItem.parentTaskId)
+					// Recursively restore parent task (which may have its own parent)
+					restoredParentTask = await this.createTaskWithHistoryItem(parentHistoryItem)
+				} catch (error) {
+					this.log(
+						`Failed to restore parent task ${historyItem.parentTaskId}: ${error instanceof Error ? error.message : String(error)}`,
+					)
+				}
+			}
+		}
+
+		if (historyItem.rootTaskId) {
+			// Try to find the root task in the current task stack
+			restoredRootTask = this.clineStack.find((task) => task.taskId === historyItem.rootTaskId)
+
+			if (!restoredRootTask && historyItem.rootTaskId !== historyItem.parentTaskId) {
+				// Root task is different from parent and not in stack
+				this.log(`Note: Root task ${historyItem.rootTaskId} not found in current stack`)
+				// We could restore root task here if needed, but usually parent is enough
+			}
+		}
+
 		const {
 			apiConfiguration,
 			diffEnabled: enableDiff,
@@ -924,8 +960,8 @@ export class ClineProvider
 			consecutiveMistakeLimit: apiConfiguration.consecutiveMistakeLimit,
 			historyItem,
 			experiments,
-			rootTask: historyItem.rootTask,
-			parentTask: historyItem.parentTask,
+			rootTask: restoredRootTask || historyItem.rootTask,
+			parentTask: restoredParentTask || historyItem.parentTask,
 			taskNumber: historyItem.number,
 			workspacePath: historyItem.workspace,
 			onCreated: this.taskCreationCallback,