diff --git a/src/__tests__/history-resume-delegation.spec.ts b/src/__tests__/history-resume-delegation.spec.ts
index d3238d39e3..e9b5872142 100644
--- a/src/__tests__/history-resume-delegation.spec.ts
+++ b/src/__tests__/history-resume-delegation.spec.ts
@@ -33,6 +33,19 @@ vi.mock("../core/task-persistence", () => ({
 	readApiMessages: vi.fn().mockResolvedValue([]),
 	saveApiMessages: vi.fn().mockResolvedValue(undefined),
 	saveTaskMessages: vi.fn().mockResolvedValue(undefined),
+	getPendingSubtasks: vi.fn().mockReturnValue([]),
+	// appendToolResult should actually add the tool_result to the messages
+	appendToolResult: vi.fn().mockImplementation((msgs, toolUseId, result) => {
+		const newMsgs = [...msgs]
+		newMsgs.push({
+			role: "user",
+			content: [{ type: "tool_result", tool_use_id: toolUseId, content: result }],
+			ts: Date.now(),
+		})
+		return newMsgs
+	}),
+	getOtherToolResults: vi.fn().mockReturnValue([]),
+	hasPendingSubtasksInHistory: vi.fn().mockReturnValue(false),
 }))
 
 import { ClineProvider } from "../core/webview/ClineProvider"
@@ -69,7 +82,6 @@ describe("History resume delegation - parent metadata transitions", () => {
 			taskId: "parent-1",
 			skipPrevResponseIdOnce: false,
 			resumeAfterDelegation: vi.fn().mockResolvedValue(undefined),
-			loadPendingSubtasks: vi.fn(),
 			hasPendingSubtasks: vi.fn().mockReturnValue(false),
 		})
 
@@ -81,9 +93,6 @@ describe("History resume delegation - parent metadata transitions", () => {
 			removeClineFromStack,
 			createTaskWithHistoryItem,
 			updateTaskHistory,
-			getSubtaskState: vi.fn().mockReturnValue(undefined),
-			setSubtaskState: vi.fn().mockResolvedValue(undefined),
-			clearSubtaskState: vi.fn().mockResolvedValue(undefined),
 		} as unknown as ClineProvider
 
 		// Mock persistence reads to return empty arrays
@@ -148,13 +157,9 @@ describe("History resume delegation - parent metadata transitions", () => {
 				resumeAfterDelegation: vi.fn().mockResolvedValue(undefined),
 				overwriteClineMessages: vi.fn().mockResolvedValue(undefined),
 				overwriteApiConversationHistory: vi.fn().mockResolvedValue(undefined),
-				loadPendingSubtasks: vi.fn(),
 				hasPendingSubtasks: vi.fn().mockReturnValue(false),
 			}),
 			updateTaskHistory: vi.fn().mockResolvedValue([]),
-			getSubtaskState: vi.fn().mockReturnValue(undefined),
-			setSubtaskState: vi.fn().mockResolvedValue(undefined),
-			clearSubtaskState: vi.fn().mockResolvedValue(undefined),
 		} as unknown as ClineProvider
 
 		// Start with existing messages in history
@@ -219,13 +224,9 @@ describe("History resume delegation - parent metadata transitions", () => {
 				resumeAfterDelegation: vi.fn().mockResolvedValue(undefined),
 				overwriteClineMessages: vi.fn().mockResolvedValue(undefined),
 				overwriteApiConversationHistory: vi.fn().mockResolvedValue(undefined),
-				loadPendingSubtasks: vi.fn(),
 				hasPendingSubtasks: vi.fn().mockReturnValue(false),
 			}),
 			updateTaskHistory: vi.fn().mockResolvedValue([]),
-			getSubtaskState: vi.fn().mockReturnValue(undefined),
-			setSubtaskState: vi.fn().mockResolvedValue(undefined),
-			clearSubtaskState: vi.fn().mockResolvedValue(undefined),
 		} as unknown as ClineProvider
 
 		// Include an assistant message with new_task tool_use to exercise the tool_result path
@@ -295,7 +296,6 @@ describe("History resume delegation - parent metadata transitions", () => {
 			}),
 			overwriteClineMessages: vi.fn().mockResolvedValue(undefined),
 			overwriteApiConversationHistory: vi.fn().mockResolvedValue(undefined),
-			loadPendingSubtasks: vi.fn(),
 			hasPendingSubtasks: vi.fn().mockReturnValue(false),
 		}
 
@@ -319,9 +319,6 @@ describe("History resume delegation - parent metadata transitions", () => {
 			removeClineFromStack: vi.fn().mockResolvedValue(undefined),
 			createTaskWithHistoryItem: vi.fn().mockResolvedValue(parentInstance),
 			updateTaskHistory: vi.fn().mockResolvedValue([]),
-			getSubtaskState: vi.fn().mockReturnValue(undefined),
-			setSubtaskState: vi.fn().mockResolvedValue(undefined),
-			clearSubtaskState: vi.fn().mockResolvedValue(undefined),
 		} as unknown as ClineProvider
 
 		vi.mocked(readTaskMessages).mockResolvedValue([])
@@ -363,13 +360,9 @@ describe("History resume delegation - parent metadata transitions", () => {
 				resumeAfterDelegation: vi.fn().mockResolvedValue(undefined),
 				overwriteClineMessages: vi.fn().mockResolvedValue(undefined),
 				overwriteApiConversationHistory: vi.fn().mockResolvedValue(undefined),
-				loadPendingSubtasks: vi.fn(),
 				hasPendingSubtasks: vi.fn().mockReturnValue(false),
 			}),
 			updateTaskHistory: vi.fn().mockResolvedValue([]),
-			getSubtaskState: vi.fn().mockReturnValue(undefined),
-			setSubtaskState: vi.fn().mockResolvedValue(undefined),
-			clearSubtaskState: vi.fn().mockResolvedValue(undefined),
 		} as unknown as ClineProvider
 
 		vi.mocked(readTaskMessages).mockResolvedValue([])
@@ -418,13 +411,9 @@ describe("History resume delegation - parent metadata transitions", () => {
 				resumeAfterDelegation: vi.fn().mockResolvedValue(undefined),
 				overwriteClineMessages: vi.fn().mockResolvedValue(undefined),
 				overwriteApiConversationHistory: vi.fn().mockResolvedValue(undefined),
-				loadPendingSubtasks: vi.fn(),
 				hasPendingSubtasks: vi.fn().mockReturnValue(false),
 			}),
 			updateTaskHistory: vi.fn().mockResolvedValue([]),
-			getSubtaskState: vi.fn().mockReturnValue(undefined),
-			setSubtaskState: vi.fn().mockResolvedValue(undefined),
-			clearSubtaskState: vi.fn().mockResolvedValue(undefined),
 		} as unknown as ClineProvider
 
 		vi.mocked(readTaskMessages).mockResolvedValue([])
@@ -466,13 +455,9 @@ describe("History resume delegation - parent metadata transitions", () => {
 				resumeAfterDelegation: vi.fn().mockResolvedValue(undefined),
 				overwriteClineMessages: vi.fn().mockResolvedValue(undefined),
 				overwriteApiConversationHistory: vi.fn().mockResolvedValue(undefined),
-				loadPendingSubtasks: vi.fn(),
 				hasPendingSubtasks: vi.fn().mockReturnValue(false),
 			}),
 			updateTaskHistory: vi.fn().mockResolvedValue([]),
-			getSubtaskState: vi.fn().mockReturnValue(undefined),
-			setSubtaskState: vi.fn().mockResolvedValue(undefined),
-			clearSubtaskState: vi.fn().mockResolvedValue(undefined),
 		} as unknown as ClineProvider
 
 		// Mock read failures or empty returns
diff --git a/src/__tests__/nested-delegation-resume.spec.ts b/src/__tests__/nested-delegation-resume.spec.ts
index f649a29799..88e1ddbde2 100644
--- a/src/__tests__/nested-delegation-resume.spec.ts
+++ b/src/__tests__/nested-delegation-resume.spec.ts
@@ -47,6 +47,19 @@ vi.mock("../core/task-persistence", () => ({
 	readApiMessages: vi.fn().mockResolvedValue([]),
 	saveApiMessages: vi.fn().mockResolvedValue(undefined),
 	saveTaskMessages: vi.fn().mockResolvedValue(undefined),
+	getPendingSubtasks: vi.fn().mockReturnValue([]),
+	// appendToolResult should actually add the tool_result to the messages
+	appendToolResult: vi.fn().mockImplementation((msgs, toolUseId, result) => {
+		const newMsgs = [...msgs]
+		newMsgs.push({
+			role: "user",
+			content: [{ type: "tool_result", tool_use_id: toolUseId, content: result }],
+			ts: Date.now(),
+		})
+		return newMsgs
+	}),
+	getOtherToolResults: vi.fn().mockReturnValue([]),
+	hasPendingSubtasksInHistory: vi.fn().mockReturnValue(false),
 }))
 
 import { attemptCompletionTool } from "../core/tools/AttemptCompletionTool"
@@ -57,7 +70,7 @@ import { readApiMessages, saveApiMessages, saveTaskMessages } from "../core/task
 
 describe("Nested delegation resume (A → B → C)", () => {
 	beforeEach(() => {
-		vi.restoreAllMocks()
+		vi.clearAllMocks()
 	})
 
 	it("C completes → reopens B; then B completes → reopens A; emits correct events; no resume_task asks", async () => {
@@ -128,7 +141,6 @@ describe("Nested delegation resume (A → B → C)", () => {
 					resumeAfterDelegation: vi.fn().mockResolvedValue(undefined),
 					overwriteClineMessages: vi.fn().mockResolvedValue(undefined),
 					overwriteApiConversationHistory: vi.fn().mockResolvedValue(undefined),
-					loadPendingSubtasks: vi.fn(),
 					hasPendingSubtasks: vi.fn().mockReturnValue(false),
 				}
 			})
@@ -158,9 +170,6 @@ describe("Nested delegation resume (A → B → C)", () => {
 			removeClineFromStack,
 			createTaskWithHistoryItem,
 			updateTaskHistory,
-			getSubtaskState: vi.fn().mockReturnValue(undefined),
-			setSubtaskState: vi.fn().mockResolvedValue(undefined),
-			clearSubtaskState: vi.fn().mockResolvedValue(undefined),
 			// Wire through provider method so attemptCompletionTool can call it
 			reopenParentFromDelegation: vi.fn(async (params: any) => {
 				return await (ClineProvider.prototype as any).reopenParentFromDelegation.call(provider, params)
diff --git a/src/__tests__/provider-delegation.spec.ts b/src/__tests__/provider-delegation.spec.ts
index 601b0bc94a..ccee6c6188 100644
--- a/src/__tests__/provider-delegation.spec.ts
+++ b/src/__tests__/provider-delegation.spec.ts
@@ -2,6 +2,18 @@
 
 import { describe, it, expect, vi } from "vitest"
 import { RooCodeEventName } from "@roo-code/types"
+
+// Mock task-persistence to avoid undefined apiMessages error
+vi.mock("../core/task-persistence", () => ({
+	readApiMessages: vi.fn().mockResolvedValue([]),
+	saveApiMessages: vi.fn().mockResolvedValue(undefined),
+	saveTaskMessages: vi.fn().mockResolvedValue(undefined),
+	getPendingSubtasks: vi.fn().mockReturnValue([]),
+	appendToolResult: vi.fn().mockImplementation((msgs) => msgs),
+	getOtherToolResults: vi.fn().mockReturnValue([]),
+	hasPendingSubtasksInHistory: vi.fn().mockReturnValue(false),
+}))
+
 import { ClineProvider } from "../core/webview/ClineProvider"
 
 describe("ClineProvider.delegateParentAndOpenChild()", () => {
@@ -47,7 +59,6 @@ describe("ClineProvider.delegateParentAndOpenChild()", () => {
 			updateTaskHistory,
 			handleModeSwitch,
 			log: vi.fn(),
-			getSubtaskState: vi.fn().mockReturnValue(undefined),
 		} as unknown as ClineProvider
 
 		const params = {
diff --git a/src/core/task-persistence/index.ts b/src/core/task-persistence/index.ts
index c8656002bd..bbe8c20009 100644
--- a/src/core/task-persistence/index.ts
+++ b/src/core/task-persistence/index.ts
@@ -1,3 +1,15 @@
 export { type ApiMessage, readApiMessages, saveApiMessages } from "./apiMessages"
 export { readTaskMessages, saveTaskMessages } from "./taskMessages"
 export { taskMetadata } from "./taskMetadata"
+export {
+	type PendingSubtask,
+	getPendingSubtasks,
+	getPendingSubtasksFromContent,
+	getFirstPendingSubtaskId,
+	hasPendingSubtasksInHistory,
+	appendToolResult,
+	getOtherToolResults,
+	areAllSubtasksComplete,
+	getCompletedSubtaskCount,
+	getTotalSubtaskCount,
+} from "./subtaskState"
diff --git a/src/core/task-persistence/subtaskState.ts b/src/core/task-persistence/subtaskState.ts
new file mode 100644
index 0000000000..a9385f6e63
--- /dev/null
+++ b/src/core/task-persistence/subtaskState.ts
@@ -0,0 +1,305 @@
+import { Anthropic } from "@anthropic-ai/sdk"
+import { TodoItem } from "@roo-code/types"
+import { parseMarkdownChecklist } from "../tools/UpdateTodoListTool"
+
+import { type ApiMessage } from "./apiMessages"
+
+/**
+ * Represents a pending subtask derived from the API conversation history.
+ */
+export interface PendingSubtask {
+	toolCallId: string
+	message: string
+	mode: string
+	todoItems: TodoItem[]
+}
+
+/**
+ * Helper to extract pending subtasks from assistant content and existing tool results.
+ * Used internally by both getPendingSubtasks and getPendingSubtasksFromContent.
+ */
+function extractPendingSubtasks(
+	assistantContent: Array<Anthropic.Messages.ContentBlockParam | Anthropic.ToolResultBlockParam>,
+	completedToolIds: Set<string>,
+): PendingSubtask[] {
+	const newTaskToolUses = assistantContent.filter(
+		(block): block is Anthropic.Messages.ToolUseBlock => block.type === "tool_use" && block.name === "new_task",
+	)
+
+	return newTaskToolUses
+		.filter((toolUse) => !completedToolIds.has(toolUse.id))
+		.map((toolUse) => {
+			const input = toolUse.input as Record<string, unknown>
+			let todoItems: TodoItem[] = []
+
+			if (input.todos && typeof input.todos === "string") {
+				try {
+					todoItems = parseMarkdownChecklist(input.todos)
+				} catch {
+					todoItems = []
+				}
+			}
+
+			return {
+				toolCallId: toolUse.id,
+				message: (input.message as string) || "",
+				mode: (input.mode as string) || "",
+				todoItems,
+			}
+		})
+}
+
+/**
+ * Gets pending new_task tool calls that don't have tool_results yet.
+ * This derives the pending subtasks by comparing tool_use blocks (with name: "new_task")
+ * in the last assistant message against tool_result blocks in the last user message.
+ *
+ * @param apiMessages - The API conversation history
+ * @returns Array of pending subtasks with their parameters
+ */
+export function getPendingSubtasks(apiMessages: ApiMessage[]): PendingSubtask[] {
+	if (apiMessages.length < 2) return []
+
+	const lastAssistant = apiMessages[apiMessages.length - 2]
+	const lastUser = apiMessages[apiMessages.length - 1]
+
+	if (lastAssistant?.role !== "assistant" || lastUser?.role !== "user") return []
+
+	const assistantContent = Array.isArray(lastAssistant.content) ? lastAssistant.content : []
+	const userContent = Array.isArray(lastUser.content) ? lastUser.content : []
+	const completedIds = new Set(
+		userContent
+			.filter((block): block is Anthropic.ToolResultBlockParam => block.type === "tool_result")
+			.map((block) => block.tool_use_id),
+	)
+
+	return extractPendingSubtasks(assistantContent, completedIds)
+}
+
+/**
+ * Gets pending new_task tool calls by examining both API history and in-memory state.
+ * This handles two scenarios:
+ *
+ * 1. DURING streaming: user message not in history yet, tool_results in pendingToolResults
+ *    - apiMessages ends with assistant message
+ *    - pendingToolResults has executed tool results
+ *
+ * 2. AFTER delegation resume: user message already in history with tool_results
+ *    - apiMessages ends with user message (containing tool_result)
+ *    - pendingToolResults is empty
+ *
+ * @param apiMessages - The API conversation history
+ * @param pendingToolResults - In-memory tool_result blocks not yet saved to history
+ * @returns Array of pending subtasks with their parameters
+ */
+export function getPendingSubtasksFromContent(
+	apiMessages: ApiMessage[],
+	pendingToolResults: Array<Anthropic.TextBlockParam | Anthropic.ImageBlockParam | Anthropic.ToolResultBlockParam>,
+): PendingSubtask[] {
+	if (apiMessages.length < 1) return []
+
+	// Find the last assistant message
+	let lastAssistant: ApiMessage | undefined
+	let lastAssistantIndex = -1
+	for (let i = apiMessages.length - 1; i >= 0; i--) {
+		if (apiMessages[i].role === "assistant") {
+			lastAssistant = apiMessages[i]
+			lastAssistantIndex = i
+			break
+		}
+	}
+
+	if (!lastAssistant) return []
+
+	const assistantContent = Array.isArray(lastAssistant.content) ? lastAssistant.content : []
+
+	// Collect completed IDs from multiple sources:
+	// 1. In-memory pendingToolResults (during streaming)
+	// 2. Any user message that comes AFTER the last assistant message (after delegation resume)
+	const completedIds = new Set<string>()
+
+	// Source 1: In-memory tool results
+	for (const block of pendingToolResults) {
+		if (block.type === "tool_result") {
+			completedIds.add(block.tool_use_id)
+		}
+	}
+
+	// Source 2: User messages after the last assistant message
+	for (let i = lastAssistantIndex + 1; i < apiMessages.length; i++) {
+		const msg = apiMessages[i]
+		if (msg.role === "user" && Array.isArray(msg.content)) {
+			for (const block of msg.content) {
+				if (block.type === "tool_result") {
+					completedIds.add((block as Anthropic.ToolResultBlockParam).tool_use_id)
+				}
+			}
+		}
+	}
+
+	return extractPendingSubtasks(assistantContent, completedIds)
+}
+
+/**
+ * Gets the tool_use ID of the first pending new_task subtask.
+ * Used to determine which subtask is currently executing.
+ *
+ * @param apiMessages - The API conversation history
+ * @returns The tool_use ID of the first pending subtask, or undefined if none
+ */
+export function getFirstPendingSubtaskId(apiMessages: ApiMessage[]): string | undefined {
+	const pending = getPendingSubtasks(apiMessages)
+	return pending.length > 0 ? pending[0].toolCallId : undefined
+}
+
+/**
+ * Checks if there are any pending new_task subtasks.
+ *
+ * @param apiMessages - The API conversation history
+ * @returns True if there are pending subtasks
+ */
+export function hasPendingSubtasksInHistory(apiMessages: ApiMessage[]): boolean {
+	return getPendingSubtasks(apiMessages).length > 0
+}
+
+/**
+ * Appends a tool_result to the last user message in the API conversation history.
+ * If the last message is not a user message, creates a new user message.
+ *
+ * This function modifies the input array in place and returns it.
+ *
+ * @param apiMessages - The API conversation history (modified in place)
+ * @param toolUseId - The tool_use_id to reference in the tool_result
+ * @param result - The result content for the tool_result
+ * @returns The modified apiMessages array
+ */
+export function appendToolResult(apiMessages: ApiMessage[], toolUseId: string, result: string): ApiMessage[] {
+	if (apiMessages.length === 0) {
+		apiMessages.push({
+			role: "user",
+			content: [{ type: "tool_result", tool_use_id: toolUseId, content: result }],
+			ts: Date.now(),
+		})
+		return apiMessages
+	}
+
+	const lastMsg = apiMessages[apiMessages.length - 1]
+
+	if (lastMsg?.role !== "user") {
+		apiMessages.push({
+			role: "user",
+			content: [{ type: "tool_result", tool_use_id: toolUseId, content: result }],
+			ts: Date.now(),
+		})
+	} else {
+		if (!Array.isArray(lastMsg.content)) {
+			lastMsg.content = lastMsg.content ? [{ type: "text", text: lastMsg.content }] : []
+		}
+		;(lastMsg.content as Anthropic.ToolResultBlockParam[]).push({
+			type: "tool_result",
+			tool_use_id: toolUseId,
+			content: result,
+		})
+	}
+
+	return apiMessages
+}
+
+/**
+ * Gets tool_result blocks from the last user message that are NOT for new_task tool calls.
+ * These are "other" tool results (like update_todo_list) that were called in the same turn.
+ *
+ * @param apiMessages - The API conversation history
+ * @returns Array of tool_result blocks for non-new_task tools
+ */
+export function getOtherToolResults(apiMessages: ApiMessage[]): Anthropic.ToolResultBlockParam[] {
+	if (apiMessages.length < 2) return []
+
+	const lastAssistant = apiMessages[apiMessages.length - 2]
+	const lastUser = apiMessages[apiMessages.length - 1]
+
+	if (lastAssistant?.role !== "assistant" || lastUser?.role !== "user") return []
+
+	const assistantContent = Array.isArray(lastAssistant.content) ? lastAssistant.content : []
+	const newTaskToolIds = new Set(
+		assistantContent
+			.filter(
+				(block): block is Anthropic.Messages.ToolUseBlock =>
+					block.type === "tool_use" && block.name === "new_task",
+			)
+			.map((block) => block.id),
+	)
+
+	const userContent = Array.isArray(lastUser.content) ? lastUser.content : []
+	return userContent.filter(
+		(block): block is Anthropic.ToolResultBlockParam =>
+			block.type === "tool_result" && !newTaskToolIds.has(block.tool_use_id),
+	)
+}
+
+/**
+ * Checks if all new_task tool calls have corresponding tool_results.
+ * This indicates all subtasks have completed.
+ *
+ * @param apiMessages - The API conversation history
+ * @returns True if all new_task tool calls have tool_results
+ */
+export function areAllSubtasksComplete(apiMessages: ApiMessage[]): boolean {
+	return getPendingSubtasks(apiMessages).length === 0
+}
+
+/**
+ * Gets the count of completed new_task subtasks (those with tool_results).
+ *
+ * @param apiMessages - The API conversation history
+ * @returns Number of completed subtasks
+ */
+export function getCompletedSubtaskCount(apiMessages: ApiMessage[]): number {
+	if (apiMessages.length < 2) return 0
+
+	const lastAssistant = apiMessages[apiMessages.length - 2]
+	const lastUser = apiMessages[apiMessages.length - 1]
+
+	if (lastAssistant?.role !== "assistant" || lastUser?.role !== "user") return 0
+
+	const assistantContent = Array.isArray(lastAssistant.content) ? lastAssistant.content : []
+	const newTaskToolIds = new Set(
+		assistantContent
+			.filter(
+				(block): block is Anthropic.Messages.ToolUseBlock =>
+					block.type === "tool_use" && block.name === "new_task",
+			)
+			.map((block) => block.id),
+	)
+
+	const userContent = Array.isArray(lastUser.content) ? lastUser.content : []
+	return userContent.filter(
+		(block): block is Anthropic.ToolResultBlockParam =>
+			block.type === "tool_result" && newTaskToolIds.has(block.tool_use_id),
+	).length
+}
+
+/**
+ * Gets the total count of new_task tool calls in the last assistant message.
+ *
+ * @param apiMessages - The API conversation history
+ * @returns Total number of new_task tool calls
+ */
+export function getTotalSubtaskCount(apiMessages: ApiMessage[]): number {
+	if (apiMessages.length < 1) return 0
+
+	let lastAssistant: ApiMessage | undefined
+	for (let i = apiMessages.length - 1; i >= 0; i--) {
+		if (apiMessages[i].role === "assistant") {
+			lastAssistant = apiMessages[i]
+			break
+		}
+	}
+
+	if (!lastAssistant) return 0
+
+	const assistantContent = Array.isArray(lastAssistant.content) ? lastAssistant.content : []
+	return assistantContent.filter(
+		(block): block is Anthropic.Messages.ToolUseBlock => block.type === "tool_use" && block.name === "new_task",
+	).length
+}
diff --git a/src/core/task/Task.ts b/src/core/task/Task.ts
index b95d1f3149..722e6941b3 100644
--- a/src/core/task/Task.ts
+++ b/src/core/task/Task.ts
@@ -109,6 +109,9 @@ import {
 	readTaskMessages,
 	saveTaskMessages,
 	taskMetadata,
+	getPendingSubtasks,
+	getPendingSubtasksFromContent,
+	getOtherToolResults,
 } from "../task-persistence"
 import { getEnvironmentDetails } from "../environment/getEnvironmentDetails"
 import { checkContextWindowExceededError } from "../context/context-management/context-error-handling"
@@ -161,27 +164,6 @@ export class Task extends EventEmitter<TaskEvents> implements TaskLike {
 	childTaskId?: string
 	pendingNewTaskToolCallId?: string
 
-	/** Queue of subtasks to execute sequentially when multiple new_task calls are made in parallel. */
-	pendingSubtasks: Array<{
-		toolCallId: string
-		message: string
-		mode: string
-		todoItems: TodoItem[]
-	}> = []
-
-	/** Results from completed subtasks, added to conversation only after ALL subtasks finish. */
-	completedSubtaskResults: Array<{
-		toolCallId: string
-		result: string
-	}> = []
-
-	/** Pending tool results from OTHER tools called in the same turn.
-	 * Saved with subtask state so they're combined with subtask results at the end. */
-	pendingOtherToolResults: Array<Anthropic.ToolResultBlockParam> = []
-
-	/** Tool call ID of the currently-executing subtask. */
-	currentSubtaskToolCallId?: string
-
 	readonly instanceId: string
 	readonly metadata: TaskMetadata
 
@@ -842,9 +824,15 @@ export class Task extends EventEmitter<TaskEvents> implements TaskLike {
 		this.userMessageContent = []
 	}
 
-	/** Execute pending subtasks sequentially. Returns empty array since delegation suspends the parent. */
+	/**
+	 * Execute pending subtasks sequentially, deriving pending subtasks from api_conversation_history
+	 * and in-memory userMessageContent.
+	 * Returns empty array since delegation suspends the parent.
+	 */
 	public async executePendingSubtasks(): Promise<Array<{ toolCallId: string; result: string }>> {
-		if (this.pendingSubtasks.length === 0) {
+		// Derive pending subtasks - use the in-memory version since user message may not be in history yet
+		const pendingSubtasks = getPendingSubtasksFromContent(this.apiConversationHistory, this.userMessageContent)
+		if (pendingSubtasks.length === 0) {
 			return []
 		}
 
@@ -853,35 +841,31 @@ export class Task extends EventEmitter<TaskEvents> implements TaskLike {
 			throw new Error("Provider not available for subtask execution")
 		}
 
-		// Save other tool results (like update_todo_list) that were called in the same turn.
-		// Don't flush them to history yet - they'll be combined with subtask results later.
-		// Only save non-new_task tool results (filter out new_task tool results which are pending subtasks).
-		const pendingSubtaskToolIds = new Set(this.pendingSubtasks.map((s) => s.toolCallId))
-		if (this.currentSubtaskToolCallId) {
-			pendingSubtaskToolIds.add(this.currentSubtaskToolCallId)
+		// Before delegating first subtask, flush other tool results to api_conversation_history.
+		// We need to create a user message with ALL tool_results including a placeholder for this new_task.
+		// This ensures the API conversation is valid (every tool_use has a tool_result).
+
+		// Get all new_task tool IDs from the last assistant message
+		const newTaskToolIds = new Set(pendingSubtasks.map((s) => s.toolCallId))
+
+		// Find non-new_task tool results in userMessageContent
+		const nonNewTaskToolResults = this.userMessageContent.filter(
+			(block): block is Anthropic.ToolResultBlockParam =>
+				block.type === "tool_result" && !newTaskToolIds.has(block.tool_use_id),
+		)
+
+		// Flush all pending tool results (for non-new_task tools) to history
+		if (nonNewTaskToolResults.length > 0) {
+			await this.flushPendingToolResultsToHistory()
+		} else {
+			// Clear userMessageContent since we're about to delegate
+			this.userMessageContent = []
 		}
 
-		// Extract tool_result blocks from userMessageContent that are NOT subtask-related
-		const otherToolResults = this.userMessageContent.filter((block): block is Anthropic.ToolResultBlockParam => {
-			if (block.type !== "tool_result") return false
-			return !pendingSubtaskToolIds.has(block.tool_use_id)
-		})
-
-		// If this is the first subtask, save the other tool results
-		if (this.pendingOtherToolResults.length === 0 && otherToolResults.length > 0) {
-			this.pendingOtherToolResults = otherToolResults
-		}
-
-		// Clear userMessageContent since we're about to delegate (don't flush to history)
-		this.userMessageContent = []
-
-		const currentSubtask = this.pendingSubtasks.shift()!
-		this.currentSubtaskToolCallId = currentSubtask.toolCallId
+		// Get the first pending subtask to execute
+		const currentSubtask = pendingSubtasks[0]
 
 		try {
-			// State must be saved before delegating since a new parent instance is created on resume
-			await this.savePendingSubtasks()
-
 			await (provider as any).delegateParentAndOpenChild({
 				parentTaskId: this.taskId,
 				message: currentSubtask.message,
@@ -890,91 +874,21 @@ export class Task extends EventEmitter<TaskEvents> implements TaskLike {
 			})
 		} catch (error) {
 			const errorMessage = error instanceof Error ? error.message : String(error)
-			this.completedSubtaskResults.push({
-				toolCallId: currentSubtask.toolCallId,
-				result: `Failed to execute subtask: ${errorMessage}`,
-			})
-			this.currentSubtaskToolCallId = undefined
-			await this.savePendingSubtasks()
+			console.error(`[Task#executePendingSubtasks] Failed to execute subtask: ${errorMessage}`)
 		}
 
 		return []
 	}
 
+	/**
+	 * Check if there are pending subtasks by examining api_conversation_history
+	 * and in-memory userMessageContent.
+	 * Pending = new_task tool_use blocks without corresponding tool_result blocks.
+	 */
 	public hasPendingSubtasks(): boolean {
-		return this.pendingSubtasks.length > 0
-	}
-
-	/**
-	 * Save subtask state to VSCode's workspaceState via the provider.
-	 * The workspaceState persists across extension restarts, so this state survives
-	 * when the parent is disposed and recreated after a child task completes.
-	 */
-	public async savePendingSubtasks(): Promise<void> {
-		const provider = this.providerRef.deref()
-		if (!provider) {
-			console.error(`[Task#savePendingSubtasks] Provider not available`)
-			return
-		}
-
-		const hasState =
-			this.pendingSubtasks.length > 0 ||
-			this.completedSubtaskResults.length > 0 ||
-			this.currentSubtaskToolCallId ||
-			this.pendingOtherToolResults.length > 0
-
-		if (hasState) {
-			await provider.setSubtaskState(this.taskId, {
-				pendingSubtasks: this.pendingSubtasks,
-				completedSubtaskResults: this.completedSubtaskResults,
-				currentSubtaskToolCallId: this.currentSubtaskToolCallId,
-				pendingOtherToolResults: this.pendingOtherToolResults as any,
-			})
-		} else {
-			// Clean up state if nothing to store
-			await provider.clearSubtaskState(this.taskId)
-		}
-	}
-
-	/**
-	 * Load subtask state from workspaceState via the provider.
-	 * Called when the parent resumes after a child task completes.
-	 */
-	public loadPendingSubtasks(): void {
-		const provider = this.providerRef.deref()
-		if (!provider) {
-			return
-		}
-
-		const state = provider.getSubtaskState(this.taskId)
-		if (state) {
-			if (Array.isArray(state.pendingSubtasks)) {
-				this.pendingSubtasks = state.pendingSubtasks
-			}
-			if (Array.isArray(state.completedSubtaskResults)) {
-				this.completedSubtaskResults = state.completedSubtaskResults
-			}
-			if (state.currentSubtaskToolCallId) {
-				this.currentSubtaskToolCallId = state.currentSubtaskToolCallId
-			}
-			if (Array.isArray(state.pendingOtherToolResults)) {
-				this.pendingOtherToolResults = state.pendingOtherToolResults as Anthropic.ToolResultBlockParam[]
-			}
-		}
-	}
-
-	/**
-	 * Clear subtask state from workspaceState after all subtasks are complete.
-	 */
-	public async clearSubtaskState(): Promise<void> {
-		const provider = this.providerRef.deref()
-		if (provider) {
-			await provider.clearSubtaskState(this.taskId)
-		}
-		this.pendingSubtasks = []
-		this.completedSubtaskResults = []
-		this.currentSubtaskToolCallId = undefined
-		this.pendingOtherToolResults = []
+		// Use the in-memory version since user message may not be in history yet
+		// This is called after streaming completes but before the user message is saved
+		return getPendingSubtasksFromContent(this.apiConversationHistory, this.userMessageContent).length > 0
 	}
 
 	private async saveApiConversationHistory() {
@@ -2202,11 +2116,6 @@ export class Task extends EventEmitter<TaskEvents> implements TaskLike {
 		// Save the updated history
 		await this.saveApiConversationHistory()
 
-		// Load any pending subtasks from the provider's in-memory storage.
-		// When multiple new_task tools are called in parallel, remaining subtasks are
-		// saved before each delegation. We load them here on resume.
-		this.loadPendingSubtasks()
-
 		// Check if there are pending subtasks to execute sequentially.
 		// This happens when multiple new_task tools were called in parallel -
 		// they are queued and executed one at a time.
diff --git a/src/core/tools/NewTaskTool.ts b/src/core/tools/NewTaskTool.ts
index 77ef97223b..5015cb3ec0 100644
--- a/src/core/tools/NewTaskTool.ts
+++ b/src/core/tools/NewTaskTool.ts
@@ -147,44 +147,25 @@ export class NewTaskTool extends BaseTool<"new_task"> {
 				task.checkpointSave(true)
 			}
 
-			// Queue this new_task if using native tool protocol AND there are:
-			// 1. Multiple new_task blocks (to execute sequentially), OR
-			// 2. Any remaining tool blocks after this one (so they can execute before delegation)
+			// For native tool protocol with multiple new_task blocks or remaining tools:
+			// Don't execute immediately - let the tool result accumulate in userMessageContent.
+			// After all tools process, executePendingSubtasks() will derive pending tasks from
+			// api_conversation_history (comparing tool_use vs tool_result blocks).
 			// NOTE: XML protocol processes tools one at a time, so this condition is always false for XML.
-			// We add an explicit check for clarity and defensive safety.
 			const isNativeToolProtocol = toolProtocol === "native"
 			const newTaskBlockCount = countNewTaskBlocks(task)
 			const hasRemainingTools = hasRemainingToolBlocks(task)
 
 			if (isNativeToolProtocol && (newTaskBlockCount > 1 || hasRemainingTools)) {
-				task.pendingSubtasks.push({
-					toolCallId: toolCallId ?? "",
-					message: unescapedMessage,
-					mode,
-					todoItems,
-				})
+				// Don't push to pendingSubtasks - the info is already in the assistant message's tool_use block.
+				// Just return without executing, and executePendingSubtasks() will handle it later.
 				return
 			}
 
-			// Save other tool results (e.g., update_todo_list) that were called in the same turn.
-			// This prevents them from being lost or incorrectly ordered when the parent resumes.
-			const currentToolCallId = toolCallId ?? ""
-			const otherToolResults = task.userMessageContent.filter(
-				(block): block is Anthropic.ToolResultBlockParam =>
-					block.type === "tool_result" && block.tool_use_id !== currentToolCallId,
-			)
-
-			if (otherToolResults.length > 0) {
-				task.pendingOtherToolResults = otherToolResults
-			}
-
-			// Track this subtask and clear userMessageContent to prevent incorrect flushing
-			task.currentSubtaskToolCallId = currentToolCallId
+			// For single new_task call or XML protocol, delegate immediately.
+			// Clear userMessageContent to prevent incorrect flushing during delegation.
 			task.userMessageContent = []
 
-			// Save state before delegation so it survives parent disposal
-			await task.savePendingSubtasks()
-
 			const child = await (provider as any).delegateParentAndOpenChild({
 				parentTaskId: task.taskId,
 				message: unescapedMessage,
diff --git a/src/core/tools/__tests__/newTaskTool.spec.ts b/src/core/tools/__tests__/newTaskTool.spec.ts
index 0b4fbb9614..6270702b05 100644
--- a/src/core/tools/__tests__/newTaskTool.spec.ts
+++ b/src/core/tools/__tests__/newTaskTool.spec.ts
@@ -99,9 +99,6 @@ const mockCline = {
 	checkpointSave: mockCheckpointSave,
 	startSubtask: mockStartSubtask,
 	userMessageContent: [] as any[],
-	pendingOtherToolResults: [] as any[],
-	currentSubtaskToolCallId: undefined as string | undefined,
-	savePendingSubtasks: vi.fn().mockResolvedValue(undefined),
 	providerRef: {
 		deref: vi.fn(() => ({
 			getState: vi.fn(() => ({ customModes: [], mode: "ask" })),
@@ -656,9 +653,6 @@ describe("newTaskTool delegation flow", () => {
 			checkpointSave: mockCheckpointSave,
 			startSubtask: localStartSubtask,
 			userMessageContent: [] as any[],
-			pendingOtherToolResults: [] as any[],
-			currentSubtaskToolCallId: undefined as string | undefined,
-			savePendingSubtasks: vi.fn().mockResolvedValue(undefined),
 			providerRef: {
 				deref: vi.fn(() => providerSpy),
 			},
@@ -707,7 +701,10 @@ describe("newTaskTool delegation flow", () => {
 })
 
 describe("newTaskTool parallel execution", () => {
-	it("should queue subtasks when multiple new_task blocks are detected", async () => {
+	it("should defer delegation when multiple new_task blocks are detected (native protocol)", async () => {
+		// With the new approach, when multiple new_task blocks exist in native protocol,
+		// the tool just returns without executing - the subtask info is in the assistant message's
+		// tool_use blocks and will be derived by executePendingSubtasks() later.
 		const providerSpy = {
 			getState: vi.fn().mockResolvedValue({
 				mode: "ask",
@@ -717,7 +714,6 @@ describe("newTaskTool parallel execution", () => {
 			handleModeSwitch: vi.fn(),
 		} as any
 
-		const pendingSubtasks: any[] = []
 		const localCline = {
 			ask: vi.fn(),
 			sayAndCreateMissingParamError: vi.fn(),
@@ -731,9 +727,6 @@ describe("newTaskTool parallel execution", () => {
 			checkpointSave: vi.fn(),
 			startSubtask: vi.fn(),
 			userMessageContent: [] as any[],
-			pendingOtherToolResults: [] as any[],
-			currentSubtaskToolCallId: undefined as string | undefined,
-			savePendingSubtasks: vi.fn().mockResolvedValue(undefined),
 			providerRef: {
 				deref: vi.fn(() => providerSpy),
 			},
@@ -753,7 +746,7 @@ describe("newTaskTool parallel execution", () => {
 					partial: false,
 				},
 			],
-			pendingSubtasks,
+			currentStreamingContentIndex: 0,
 		}
 
 		const mockPushToolResult = vi.fn()
@@ -779,38 +772,10 @@ describe("newTaskTool parallel execution", () => {
 			toolCallId: "tool-1",
 		})
 
-		expect(pendingSubtasks.length).toBe(1)
-		expect(pendingSubtasks[0].mode).toBe("code")
-		expect(pendingSubtasks[0].message).toBe("First task")
-		expect(pendingSubtasks[0].toolCallId).toBe("tool-1")
-		expect(mockPushToolResult).not.toHaveBeenCalled()
-		expect(providerSpy.delegateParentAndOpenChild).not.toHaveBeenCalled()
-
-		const block2: ToolUse = {
-			type: "tool_use",
-			id: "tool-2",
-			name: "new_task",
-			params: {
-				mode: "code",
-				message: "Second task",
-			},
-			partial: false,
-		}
-
-		await newTaskTool.handle(localCline as any, block2 as ToolUse<"new_task">, {
-			askApproval: mockAskApproval,
-			handleError: vi.fn(),
-			pushToolResult: mockPushToolResult,
-			removeClosingTag: vi.fn((_: string, v?: string) => v ?? ""),
-			toolProtocol: "native", // Native protocol is required for parallel tool execution
-			toolCallId: "tool-2",
-		})
-
-		expect(pendingSubtasks.length).toBe(2)
-		expect(pendingSubtasks[1].mode).toBe("code")
-		expect(pendingSubtasks[1].message).toBe("Second task")
-		expect(pendingSubtasks[1].toolCallId).toBe("tool-2")
+		// With new approach: tool returns without delegating when multiple new_task blocks exist
+		// No pushToolResult call (deferred)
 		expect(mockPushToolResult).not.toHaveBeenCalled()
+		// No delegation yet (deferred to executePendingSubtasks)
 		expect(providerSpy.delegateParentAndOpenChild).not.toHaveBeenCalled()
 	})
 
@@ -824,7 +789,6 @@ describe("newTaskTool parallel execution", () => {
 			handleModeSwitch: vi.fn(),
 		} as any
 
-		const pendingSubtasks: any[] = []
 		const localCline = {
 			ask: vi.fn(),
 			sayAndCreateMissingParamError: vi.fn(),
@@ -838,9 +802,6 @@ describe("newTaskTool parallel execution", () => {
 			checkpointSave: vi.fn(),
 			startSubtask: vi.fn(),
 			userMessageContent: [] as any[],
-			pendingOtherToolResults: [] as any[],
-			currentSubtaskToolCallId: undefined as string | undefined,
-			savePendingSubtasks: vi.fn().mockResolvedValue(undefined),
 			providerRef: {
 				deref: vi.fn(() => providerSpy),
 			},
@@ -853,7 +814,7 @@ describe("newTaskTool parallel execution", () => {
 					partial: false,
 				},
 			],
-			pendingSubtasks,
+			currentStreamingContentIndex: 0,
 		}
 
 		const mockPushToolResult = vi.fn()
@@ -879,7 +840,6 @@ describe("newTaskTool parallel execution", () => {
 			toolCallId: "tool-1",
 		})
 
-		expect(pendingSubtasks.length).toBe(0)
 		expect(providerSpy.delegateParentAndOpenChild).toHaveBeenCalledWith({
 			parentTaskId: "mock-parent-task-id",
 			message: "Single task",
diff --git a/src/core/webview/ClineProvider.ts b/src/core/webview/ClineProvider.ts
index e0a6abb4c5..7f5d931ae8 100644
--- a/src/core/webview/ClineProvider.ts
+++ b/src/core/webview/ClineProvider.ts
@@ -93,7 +93,15 @@ import { getSystemPromptFilePath } from "../prompts/sections/custom-system-promp
 
 import { webviewMessageHandler } from "./webviewMessageHandler"
 import type { ClineMessage, TodoItem } from "@roo-code/types"
-import { readApiMessages, saveApiMessages, saveTaskMessages } from "../task-persistence"
+import {
+	readApiMessages,
+	saveApiMessages,
+	saveTaskMessages,
+	getPendingSubtasks,
+	appendToolResult,
+	getOtherToolResults,
+	hasPendingSubtasksInHistory,
+} from "../task-persistence"
 import { readTaskMessages } from "../task-persistence/taskMessages"
 import { getNonce } from "./getNonce"
 import { getUri } from "./getUri"
@@ -118,32 +126,6 @@ interface PendingEditOperation {
 	createdAt: number
 }
 
-/**
- * State for pending subtasks during parallel new_task execution.
- * Stored in VSCode's workspaceState for persistence across extension restarts.
- */
-export interface SubtaskState {
-	pendingSubtasks: Array<{
-		toolCallId: string
-		message: string
-		mode: string
-		todoItems: TodoItem[]
-	}>
-	completedSubtaskResults: Array<{
-		toolCallId: string
-		result: string
-	}>
-	currentSubtaskToolCallId?: string
-	/** Pending tool results from OTHER tools called in the same turn as new_task.
-	 * These are saved before the first subtask executes so they can be combined
-	 * with subtask results into a single user message when all complete. */
-	pendingOtherToolResults?: Array<{
-		type: "tool_result"
-		tool_use_id: string
-		content: string | Array<{ type: "text"; text: string } | { type: "image"; source: any }>
-	}>
-}
-
 export class ClineProvider
 	extends EventEmitter<TaskProviderEvents>
 	implements vscode.WebviewViewProvider, TelemetryPropertiesProvider, TaskProviderLike
@@ -172,9 +154,6 @@ export class ClineProvider
 	private pendingOperations: Map<string, PendingEditOperation> = new Map()
 	private static readonly PENDING_OPERATION_TIMEOUT_MS = 30000 // 30 seconds
 
-	// Storage key prefix for subtask state in VSCode workspaceState
-	private static readonly SUBTASK_STATE_KEY_PREFIX = "subtaskState:"
-
 	private cloudOrganizationsCache: CloudOrganizationMembership[] | null = null
 	private cloudOrganizationsCacheTimestamp: number | null = null
 	private static readonly CLOUD_ORGANIZATIONS_CACHE_DURATION_MS = 5 * 1000 // 5 seconds
@@ -579,47 +558,6 @@ export class ClineProvider
 		this.log(`[clearAllPendingEditOperations] Cleared all pending operations`)
 	}
 
-	// Subtask State Management
-	// These methods manage state for parallel new_task execution using VSCode's workspaceState.
-	// workspaceState persists data across extension restarts for the current workspace.
-
-	/**
-	 * Gets the subtask state key for a given task ID.
-	 */
-	private getSubtaskStateKey(taskId: string): string {
-		return `${ClineProvider.SUBTASK_STATE_KEY_PREFIX}${taskId}`
-	}
-
-	/**
-	 * Gets the subtask state for a given task ID from workspaceState.
-	 */
-	public getSubtaskState(taskId: string): SubtaskState | undefined {
-		const key = this.getSubtaskStateKey(taskId)
-		return this.context.workspaceState.get<SubtaskState>(key)
-	}
-
-	/**
-	 * Sets the subtask state for a given task ID in workspaceState.
-	 */
-	public async setSubtaskState(taskId: string, state: SubtaskState): Promise<void> {
-		const key = this.getSubtaskStateKey(taskId)
-		await this.context.workspaceState.update(key, state)
-		this.log(`[setSubtaskState] Set subtask state for task ${taskId}`)
-	}
-
-	/**
-	 * Clears the subtask state for a given task ID from workspaceState.
-	 * Should be called after all subtasks complete.
-	 */
-	public async clearSubtaskState(taskId: string): Promise<void> {
-		const key = this.getSubtaskStateKey(taskId)
-		const exists = this.context.workspaceState.get(key) !== undefined
-		await this.context.workspaceState.update(key, undefined)
-		if (exists) {
-			this.log(`[clearSubtaskState] Cleared subtask state for task ${taskId}`)
-		}
-	}
-
 	/*
 	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/
@@ -3061,16 +2999,16 @@ export class ClineProvider
 			)
 		}
 		// 2) DON'T flush pending tool results to history when we're in subtask execution flow.
-		//    The executePendingSubtasks() method saves other tool results (like update_todo_list)
-		//    to pendingOtherToolResults, which will be combined with subtask results into a
-		//    SINGLE user message when all subtasks complete. If we flush here, we'd create
+		//    The executePendingSubtasks() method handles saving other tool results that were
+		//    called in the same turn as new_task. These will be combined with subtask results
+		//    into a SINGLE user message when all subtasks complete. If we flush here, we'd create
 		//    a separate user message that breaks the conversation structure (tool results
 		//    MUST follow the assistant message that called them in a single user message).
 		//
-		//    Only flush if this is a direct delegation (no pending subtask state), which means
+		//    Only flush if this is a direct delegation (no pending subtasks in history), which means
 		//    the parent called new_task without the parallel subtask execution flow.
-		const hasSubtaskState = this.getSubtaskState(parentTaskId) !== undefined
-		if (!hasSubtaskState) {
+		const hasParallelSubtasks = hasPendingSubtasksInHistory(parent.apiConversationHistory)
+		if (!hasParallelSubtasks) {
 			try {
 				await parent.flushPendingToolResultsToHistory()
 			} catch (error) {
@@ -3151,6 +3089,12 @@ export class ClineProvider
 
 	/**
 	 * Reopen parent task from delegation with write-back and events.
+	 *
+	 * This method derives pending subtask state directly from api_conversation_history.json
+	 * instead of using workspaceState. The state is determined by comparing:
+	 * - tool_use blocks with name: "new_task" in the last assistant message
+	 * - tool_result blocks in the last user message
+	 * - Pending = tool_use.id NOT in tool_results
 	 */
 	public async reopenParentFromDelegation(params: {
 		parentTaskId: string
@@ -3183,17 +3127,6 @@ export class ClineProvider
 			parentApiMessages = []
 		}
 
-		// Load subtask state from workspaceState
-		const subtaskState = this.getSubtaskState(parentTaskId)
-		let pendingSubtasks: Array<{ toolCallId: string; message: string; mode: string; todoItems: any[] }> =
-			subtaskState?.pendingSubtasks ?? []
-		let completedSubtaskResults: Array<{ toolCallId: string; result: string }> =
-			subtaskState?.completedSubtaskResults ?? []
-		let currentSubtaskToolCallId: string | undefined = subtaskState?.currentSubtaskToolCallId
-		// Other tool results (like update_todo_list) that were called in the same turn as new_task
-		const pendingOtherToolResults: Array<{ type: string; tool_use_id: string; content: any }> =
-			(subtaskState?.pendingOtherToolResults as any) ?? []
-
 		const ts = Date.now()
 		if (!Array.isArray(parentClineMessages)) parentClineMessages = []
 		if (!Array.isArray(parentApiMessages)) parentApiMessages = []
@@ -3208,12 +3141,26 @@ export class ClineProvider
 		parentClineMessages.push(subtaskUiMessage)
 		await saveTaskMessages({ messages: parentClineMessages, taskId: parentTaskId, globalStoragePath })
 
-		// Determine the toolUseId for this subtask result
-		// Priority: 1) currentSubtaskToolCallId from state, 2) fallback to finding the last one
-		let toolUseId: string | undefined = currentSubtaskToolCallId
+		// Derive pending subtasks from the api_conversation_history
+		// The getPendingSubtasks function compares tool_use blocks vs tool_result blocks
+		const pendingSubtasksFromHistory = getPendingSubtasks(parentApiMessages)
 
-		if (!toolUseId) {
-			// Fallback: find the tool_use_id from the last assistant message's new_task tool_use
+		// Get other tool results (non-new_task tools) from the last assistant message
+		// that haven't been added to history yet
+		const otherToolResults = getOtherToolResults(parentApiMessages)
+
+		// Find the toolUseId for the child that just completed
+		// First, check if there's a pending subtask matching the child's details
+		// Since we execute subtasks in order, the first pending one should be the one that just completed
+		let toolUseId: string | undefined
+
+		// Look through assistant message to find the new_task tool_use that matches
+		// We need to find which one was being executed - look for the first pending one
+		if (pendingSubtasksFromHistory.length > 0) {
+			// The first pending subtask is the one we just completed
+			toolUseId = pendingSubtasksFromHistory[0].toolCallId
+		} else {
+			// Fallback: find the last new_task tool_use in the assistant message
 			for (let i = parentApiMessages.length - 1; i >= 0; i--) {
 				const msg = parentApiMessages[i]
 				if (msg.role === "assistant" && Array.isArray(msg.content)) {
@@ -3228,83 +3175,41 @@ export class ClineProvider
 			}
 		}
 
-		// Store this subtask's result
+		// Append the completed subtask's tool_result to the conversation history
 		if (toolUseId) {
-			completedSubtaskResults.push({
-				toolCallId: toolUseId,
-				result: `Subtask ${childTaskId} completed.\n\nResult:\n${completionResultSummary}`,
-			})
+			const resultContent = `Subtask ${childTaskId} completed.\n\nResult:\n${completionResultSummary}`
+			parentApiMessages = appendToolResult(parentApiMessages, toolUseId, resultContent)
 		}
 
-		// Clear currentSubtaskToolCallId since this subtask is complete
-		currentSubtaskToolCallId = undefined
+		// Check if there are more pending subtasks to execute after adding this result
+		const remainingPendingSubtasks = getPendingSubtasks(parentApiMessages)
+		const hasMoreSubtasks = remainingPendingSubtasks.length > 0
 
-		// Check if there are more pending subtasks to execute
-		const hasMoreSubtasks = pendingSubtasks.length > 0
-
-		if (!hasMoreSubtasks && completedSubtaskResults.length > 0) {
-			// All subtasks complete - add ALL tool_results to the conversation now
-			// The API expects: user → assistant (with tool_use) → user (with tool_result)
-
-			// Check if the last message is already a user message we can append to
+		// If no more subtasks and we have other tool results that need to be flushed,
+		// add them to the conversation (they come before subtask results)
+		if (!hasMoreSubtasks && otherToolResults.length > 0) {
+			// The other tool results should be added to the last user message
 			const lastMsg = parentApiMessages[parentApiMessages.length - 1]
-			let userMessageContent: any[] = []
-
 			if (lastMsg?.role === "user" && Array.isArray(lastMsg.content)) {
-				// Filter out any existing tool_results for our subtask IDs (to avoid duplicates)
-				const allToolResultIds = new Set([
-					...completedSubtaskResults.map((r) => r.toolCallId),
-					...pendingOtherToolResults.map((r) => r.tool_use_id),
-				])
-				userMessageContent = lastMsg.content.filter(
-					(block: any) => !(block.type === "tool_result" && allToolResultIds.has(block.tool_use_id)),
+				// Check if these results are already in the message
+				const existingToolResultIds = new Set(
+					lastMsg.content.filter((b: any) => b.type === "tool_result").map((b: any) => b.tool_use_id),
 				)
-				// Remove the last message so we can replace it with an updated one
-				parentApiMessages.pop()
+
+				// Add missing other tool results at the beginning (before subtask results)
+				const newContent = [...otherToolResults.filter((r) => !existingToolResultIds.has(r.tool_use_id))]
+
+				if (newContent.length > 0) {
+					// Insert other tool results at the beginning of the content array
+					// to maintain original tool call order
+					lastMsg.content = [...newContent, ...lastMsg.content]
+				}
 			}
-
-			// FIRST: Add other tool results (e.g., update_todo_list) that were called in the same turn
-			// These should come before subtask results to maintain the original tool call order
-			for (const toolResult of pendingOtherToolResults) {
-				userMessageContent.push({
-					type: "tool_result" as const,
-					tool_use_id: toolResult.tool_use_id,
-					content: toolResult.content,
-				})
-			}
-
-			// THEN: Add all completed subtask results as tool_result blocks
-			for (const result of completedSubtaskResults) {
-				userMessageContent.push({
-					type: "tool_result" as const,
-					tool_use_id: result.toolCallId,
-					content: result.result,
-				})
-			}
-
-			parentApiMessages.push({
-				role: "user",
-				content: userMessageContent,
-				ts,
-			})
-
-			// Clear completed results since they're now in the conversation
-			completedSubtaskResults = []
-
-			// Clean up the subtask state from workspaceState
-			await this.clearSubtaskState(parentTaskId)
-		} else {
-			// More subtasks remain - save state for the next resumption
-			await this.setSubtaskState(parentTaskId, {
-				pendingSubtasks,
-				completedSubtaskResults,
-				currentSubtaskToolCallId,
-			})
 		}
 
 		await saveApiMessages({ messages: parentApiMessages as any, taskId: parentTaskId, globalStoragePath })
 
-		// 3) Update child metadata to "completed" status
+		// 2) Update child metadata to "completed" status
 		try {
 			const { historyItem: childHistory } = await this.getTaskWithId(childTaskId)
 			await this.updateTaskHistory({
@@ -3319,7 +3224,7 @@ export class ClineProvider
 			)
 		}
 
-		// 4) Update parent metadata and persist BEFORE emitting completion event
+		// 3) Update parent metadata and persist BEFORE emitting completion event
 		const childIds = Array.from(new Set([...(historyItem.childIds ?? []), childTaskId]))
 		const updatedHistory: typeof historyItem = {
 			...historyItem,
@@ -3331,24 +3236,24 @@ export class ClineProvider
 		}
 		await this.updateTaskHistory(updatedHistory)
 
-		// 5) Emit TaskDelegationCompleted (provider-level)
+		// 4) Emit TaskDelegationCompleted (provider-level)
 		try {
 			this.emit(RooCodeEventName.TaskDelegationCompleted, parentTaskId, childTaskId, completionResultSummary)
 		} catch {
 			// non-fatal
 		}
 
-		// 6) Close child instance if still open (single-open-task invariant)
+		// 5) Close child instance if still open (single-open-task invariant)
 		const current = this.getCurrentTask()
 		if (current?.taskId === childTaskId) {
 			await this.removeClineFromStack()
 		}
 
-		// 7) Reopen the parent from history as the sole active task (restores saved mode)
+		// 6) Reopen the parent from history as the sole active task (restores saved mode)
 		//    IMPORTANT: startTask=false to suppress resume-from-history ask scheduling
 		const parentInstance = await this.createTaskWithHistoryItem(updatedHistory, { startTask: false })
 
-		// 8) Inject restored histories into the in-memory instance before resuming
+		// 7) Inject restored histories into the in-memory instance before resuming
 		if (parentInstance) {
 			try {
 				await parentInstance.overwriteClineMessages(parentClineMessages)
@@ -3361,15 +3266,13 @@ export class ClineProvider
 				// non-fatal
 			}
 
-			// Load subtask state into the parent instance (synchronous - reads from provider's in-memory state)
-			parentInstance.loadPendingSubtasks()
-
-			// Check if there are more pending subtasks to execute
-			if (parentInstance.hasPendingSubtasks()) {
+			// Check if there are more pending subtasks to execute (derived from history)
+			const pendingFromHistory = getPendingSubtasks(parentApiMessages)
+			if (pendingFromHistory.length > 0) {
 				// Execute the next pending subtask
 				// This will cause the parent to be "paused" again and a new child will run
 				this.log(
-					`[reopenParentFromDelegation] Parent ${parentTaskId} has ${parentInstance.pendingSubtasks.length} more subtasks, executing next one`,
+					`[reopenParentFromDelegation] Parent ${parentTaskId} has ${pendingFromHistory.length} more subtasks, executing next one`,
 				)
 				await parentInstance.executePendingSubtasks()
 			} else {
@@ -3378,7 +3281,7 @@ export class ClineProvider
 			}
 		}
 
-		// 9) Emit TaskDelegationResumed (provider-level)
+		// 8) Emit TaskDelegationResumed (provider-level)
 		try {
 			this.emit(RooCodeEventName.TaskDelegationResumed, parentTaskId, childTaskId)
 		} catch {