perf(webview): avoid resending taskHistory in state updates

packages/types/src/vscode-extension-host.ts

@@ -29,6 +29,8 @@ export interface ExtensionMessage {
 	type:
 		| "action"
 		| "state"
+		| "taskHistoryUpdated"
+		| "taskHistoryItemUpdated"
 		| "selectedImages"
 		| "theme"
 		| "workspaceUpdated"
@@ -114,7 +116,11 @@ export interface ExtensionMessage {
 		| "switchTab"
 		| "toggleAutoApprove"
 	invoke?: "newChat" | "sendMessage" | "primaryButtonClick" | "secondaryButtonClick" | "setChatBoxMessage"
-	state?: ExtensionState
+	/**
+	 * Partial state updates are allowed to reduce message size (e.g. omit large fields like taskHistory).
+	 * The webview is responsible for merging.
+	 */
+	state?: Partial<ExtensionState>
 	images?: string[]
 	filePaths?: string[]
 	openedTabs?: Array<{
@@ -194,6 +200,9 @@ export interface ExtensionMessage {
 		childrenCost: number
 	}
 	historyItem?: HistoryItem
+	taskHistory?: HistoryItem[] // For taskHistoryUpdated: full sorted task history
+	/** For taskHistoryItemUpdated: single updated/added history item */
+	taskHistoryItem?: HistoryItem
 }
 
 export interface OpenAiCodexRateLimitsMessage {

src/core/config/__tests__/importExport.spec.ts

@@ -458,6 +458,7 @@ describe("importExport", () => {
 			const mockProvider = {
 				settingsImportedAt: 0,
 				postStateToWebview: vi.fn().mockResolvedValue(undefined),
+				postStateToWebviewWithoutTaskHistory: vi.fn().mockResolvedValue(undefined),
 			}
 
 			// Mock the showErrorMessage to capture the error

src/core/task/Task.ts

@@ -590,7 +590,7 @@ export class Task extends EventEmitter<TaskEvents> implements TaskLike {
 
 		this.messageQueueStateChangedHandler = () => {
 			this.emit(RooCodeEventName.TaskUserMessage, this.taskId)
-			this.providerRef.deref()?.postStateToWebview()
+			this.providerRef.deref()?.postStateToWebviewWithoutTaskHistory()
 		}
 
 		this.messageQueueService.on("stateChanged", this.messageQueueStateChangedHandler)
@@ -1137,7 +1137,9 @@ export class Task extends EventEmitter<TaskEvents> implements TaskLike {
 	private async addToClineMessages(message: ClineMessage) {
 		this.clineMessages.push(message)
 		const provider = this.providerRef.deref()
-		await provider?.postStateToWebview()
+		// Avoid resending large, mostly-static fields (notably taskHistory) on every chat message update.
+		// taskHistory is maintained in-memory in the webview and updated via taskHistoryItemUpdated.
+		await provider?.postStateToWebviewWithoutTaskHistory()
 		this.emit(RooCodeEventName.Message, { action: "created", message })
 		await this.saveClineMessages()
 
@@ -1866,69 +1868,77 @@ export class Task extends EventEmitter<TaskEvents> implements TaskLike {
 	}
 
 	private async startTask(task?: string, images?: string[]): Promise<void> {
-		if (this.enableBridge) {
-			try {
-				await BridgeOrchestrator.subscribeToTask(this)
-			} catch (error) {
-				console.error(
-					`[Task#startTask] BridgeOrchestrator.subscribeToTask() failed: ${error instanceof Error ? error.message : String(error)}`,
-				)
+		try {
+			if (this.enableBridge) {
+				try {
+					await BridgeOrchestrator.subscribeToTask(this)
+				} catch (error) {
+					console.error(
+						`[Task#startTask] BridgeOrchestrator.subscribeToTask() failed: ${error instanceof Error ? error.message : String(error)}`,
+					)
+				}
 			}
-		}
-
-		// `conversationHistory` (for API) and `clineMessages` (for webview)
-		// need to be in sync.
-		// If the extension process were killed, then on restart the
-		// `clineMessages` might not be empty, so we need to set it to [] when
-		// we create a new Cline client (otherwise webview would show stale
-		// messages from previous session).
-		this.clineMessages = []
-		this.apiConversationHistory = []
 
-		// The todo list is already set in the constructor if initialTodos were provided
-		// No need to add any messages - the todoList property is already set
+			// `conversationHistory` (for API) and `clineMessages` (for webview)
+			// need to be in sync.
+			// If the extension process were killed, then on restart the
+			// `clineMessages` might not be empty, so we need to set it to [] when
+			// we create a new Cline client (otherwise webview would show stale
+			// messages from previous session).
+			this.clineMessages = []
+			this.apiConversationHistory = []
 
-		await this.providerRef.deref()?.postStateToWebview()
+			// The todo list is already set in the constructor if initialTodos were provided
+			// No need to add any messages - the todoList property is already set
 
-		await this.say("text", task, images)
+			await this.providerRef.deref()?.postStateToWebviewWithoutTaskHistory()
 
-		// Check for too many MCP tools and warn the user
-		const { enabledToolCount, enabledServerCount } = await this.getEnabledMcpToolsCount()
-		if (enabledToolCount > MAX_MCP_TOOLS_THRESHOLD) {
-			await this.say(
-				"too_many_tools_warning",
-				JSON.stringify({
-					toolCount: enabledToolCount,
-					serverCount: enabledServerCount,
-					threshold: MAX_MCP_TOOLS_THRESHOLD,
-				}),
-				undefined,
-				undefined,
-				undefined,
-				undefined,
-				{ isNonInteractive: true },
-			)
-		}
-		this.isInitialized = true
+			await this.say("text", task, images)
 
-		let imageBlocks: Anthropic.ImageBlockParam[] = formatResponse.imageBlocks(images)
+			// Check for too many MCP tools and warn the user
+			const { enabledToolCount, enabledServerCount } = await this.getEnabledMcpToolsCount()
+			if (enabledToolCount > MAX_MCP_TOOLS_THRESHOLD) {
+				await this.say(
+					"too_many_tools_warning",
+					JSON.stringify({
+						toolCount: enabledToolCount,
+						serverCount: enabledServerCount,
+						threshold: MAX_MCP_TOOLS_THRESHOLD,
+					}),
+					undefined,
+					undefined,
+					undefined,
+					undefined,
+					{ isNonInteractive: true },
+				)
+			}
+			this.isInitialized = true
 
-		// Task starting
+			const imageBlocks: Anthropic.ImageBlockParam[] = formatResponse.imageBlocks(images)
 
-		await this.initiateTaskLoop([
-			{
-				type: "text",
-				text: `<user_message>\n${task}\n</user_message>`,
-			},
-			...imageBlocks,
-		]).catch((error) => {
-			// Swallow loop rejection when the task was intentionally abandoned/aborted
-			// during delegation or user cancellation to prevent unhandled rejections.
-			if (this.abandoned === true || this.abortReason === "user_cancelled") {
+			// Task starting
+			await this.initiateTaskLoop([
+				{
+					type: "text",
+					text: `<user_message>\n${task}\n</user_message>`,
+				},
+				...imageBlocks,
+			]).catch((error) => {
+				// Swallow loop rejection when the task was intentionally abandoned/aborted
+				// during delegation or user cancellation to prevent unhandled rejections.
+				if (this.abandoned === true || this.abortReason === "user_cancelled") {
+					return
+				}
+				throw error
+			})
+		} catch (error) {
+			// In tests and some UX flows, tasks can be aborted while `startTask` is still
+			// initializing. Treat abort/abandon as expected and avoid unhandled rejections.
+			if (this.abandoned === true || this.abort === true || this.abortReason === "user_cancelled") {
 				return
 			}
 			throw error
-		})
+		}
 	}
 
 	private async resumeTaskFromHistory() {
@@ -2678,7 +2688,7 @@ export class Task extends EventEmitter<TaskEvents> implements TaskLike {
 			} satisfies ClineApiReqInfo)
 
 			await this.saveClineMessages()
-			await this.providerRef.deref()?.postStateToWebview()
+			await this.providerRef.deref()?.postStateToWebviewWithoutTaskHistory()
 
 			try {
 				let cacheWriteTokens = 0
@@ -3446,7 +3456,7 @@ export class Task extends EventEmitter<TaskEvents> implements TaskLike {
 				}
 
 				await this.saveClineMessages()
-				await this.providerRef.deref()?.postStateToWebview()
+				await this.providerRef.deref()?.postStateToWebviewWithoutTaskHistory()
 
 				// Reset parser after each complete conversation round (XML protocol only)
 				this.assistantMessageParser?.reset()

src/core/task/__tests__/Task.spec.ts

@@ -282,6 +282,7 @@ describe("Cline", () => {
 		// Mock provider methods
 		mockProvider.postMessageToWebview = vi.fn().mockResolvedValue(undefined)
 		mockProvider.postStateToWebview = vi.fn().mockResolvedValue(undefined)
+		mockProvider.postStateToWebviewWithoutTaskHistory = vi.fn().mockResolvedValue(undefined)
 		mockProvider.getTaskWithId = vi.fn().mockImplementation(async (id) => ({
 			historyItem: {
 				id,
@@ -987,6 +988,7 @@ describe("Cline", () => {
 					getSkillsManager: vi.fn().mockReturnValue(undefined),
 					say: vi.fn(),
 					postStateToWebview: vi.fn().mockResolvedValue(undefined),
+					postStateToWebviewWithoutTaskHistory: vi.fn().mockResolvedValue(undefined),
 					postMessageToWebview: vi.fn().mockResolvedValue(undefined),
 					updateTaskHistory: vi.fn().mockResolvedValue(undefined),
 				}
@@ -1901,6 +1903,7 @@ describe("Queued message processing after condense", () => {
 		const provider = new ClineProvider(ctx, output as any, "sidebar", new ContextProxy(ctx)) as any
 		provider.postMessageToWebview = vi.fn().mockResolvedValue(undefined)
 		provider.postStateToWebview = vi.fn().mockResolvedValue(undefined)
+		provider.postStateToWebviewWithoutTaskHistory = vi.fn().mockResolvedValue(undefined)
 		provider.getState = vi.fn().mockResolvedValue({})
 		return provider
 	}
@@ -2039,6 +2042,7 @@ describe("pushToolResultToUserContent", () => {
 
 		mockProvider.postMessageToWebview = vi.fn().mockResolvedValue(undefined)
 		mockProvider.postStateToWebview = vi.fn().mockResolvedValue(undefined)
+		mockProvider.postStateToWebviewWithoutTaskHistory = vi.fn().mockResolvedValue(undefined)
 	})
 
 	it("should add tool_result when not a duplicate", () => {

src/core/task/__tests__/Task.sticky-profile-race.spec.ts

@@ -121,6 +121,7 @@ describe("Task - sticky provider profile init race", () => {
 			on: vi.fn(),
 			off: vi.fn(),
 			postStateToWebview: vi.fn().mockResolvedValue(undefined),
+			postStateToWebviewWithoutTaskHistory: vi.fn().mockResolvedValue(undefined),
 			updateTaskHistory: vi.fn().mockResolvedValue(undefined),
 		} as unknown as ClineProvider
 

src/core/task/__tests__/Task.throttle.test.ts

@@ -79,6 +79,7 @@ describe("Task token usage throttling", () => {
 			getState: vi.fn().mockResolvedValue({ mode: "code" }),
 			log: vi.fn(),
 			postStateToWebview: vi.fn().mockResolvedValue(undefined),
+			postStateToWebviewWithoutTaskHistory: vi.fn().mockResolvedValue(undefined),
 			updateTaskHistory: vi.fn().mockResolvedValue(undefined),
 		}
 

src/core/task/__tests__/flushPendingToolResultsToHistory.spec.ts

@@ -210,6 +210,7 @@ describe("flushPendingToolResultsToHistory", () => {
 
 		mockProvider.postMessageToWebview = vi.fn().mockResolvedValue(undefined)
 		mockProvider.postStateToWebview = vi.fn().mockResolvedValue(undefined)
+		mockProvider.postStateToWebviewWithoutTaskHistory = vi.fn().mockResolvedValue(undefined)
 		mockProvider.updateTaskHistory = vi.fn().mockResolvedValue(undefined)
 	})
 

src/core/task/__tests__/grace-retry-errors.spec.ts

@@ -206,6 +206,7 @@ describe("Grace Retry Error Handling", () => {
 
 		mockProvider.postMessageToWebview = vi.fn().mockResolvedValue(undefined)
 		mockProvider.postStateToWebview = vi.fn().mockResolvedValue(undefined)
+		mockProvider.postStateToWebviewWithoutTaskHistory = vi.fn().mockResolvedValue(undefined)
 		mockProvider.getState = vi.fn().mockResolvedValue({})
 	})
 

src/core/task/__tests__/grounding-sources.test.ts

@@ -166,6 +166,7 @@ describe("Task grounding sources handling", () => {
 		// Mock provider with necessary methods
 		mockProvider = {
 			postStateToWebview: vi.fn().mockResolvedValue(undefined),
+			postStateToWebviewWithoutTaskHistory: vi.fn().mockResolvedValue(undefined),
 			getState: vi.fn().mockResolvedValue({
 				mode: "code",
 				experiments: {},

src/core/task/__tests__/reasoning-preservation.test.ts

@@ -166,6 +166,7 @@ describe("Task reasoning preservation", () => {
 		// Mock provider with necessary methods
 		mockProvider = {
 			postStateToWebview: vi.fn().mockResolvedValue(undefined),
+			postStateToWebviewWithoutTaskHistory: vi.fn().mockResolvedValue(undefined),
 			getState: vi.fn().mockResolvedValue({
 				mode: "code",
 				experiments: {},

src/core/webview/ClineProvider.ts

@@ -1822,6 +1822,25 @@ export class ClineProvider
 		}
 	}
 
+	/**
+	 * Like postStateToWebview but intentionally omits taskHistory.
+	 *
+	 * Rationale:
+	 * - taskHistory can be large and was being resent on every chat message update.
+	 * - The webview maintains taskHistory in-memory and receives updates via
+	 *   `taskHistoryUpdated` / `taskHistoryItemUpdated`.
+	 */
+	async postStateToWebviewWithoutTaskHistory(): Promise<void> {
+		const state = await this.getStateToPostToWebview()
+		const { taskHistory: _omit, ...rest } = state
+		this.postMessageToWebview({ type: "state", state: rest })
+
+		// Preserve existing MDM redirect behavior
+		if (this.mdmService?.requiresCloudAuth() && !this.checkMdmCompliance()) {
+			await this.postMessageToWebview({ type: "action", action: "cloudButtonClicked" })
+		}
+	}
+
 	/**
 	 * Fetches marketplace data on demand to avoid blocking main state updates
 	 */
@@ -2474,11 +2493,19 @@ export class ClineProvider
 		}
 	}
 
-	async updateTaskHistory(item: HistoryItem): Promise<HistoryItem[]> {
+	/**
+	 * Updates a task in the task history and optionally broadcasts the updated history to the webview.
+	 * @param item The history item to update or add
+	 * @param options.broadcast Whether to broadcast the updated history to the webview (default: true)
+	 * @returns The updated task history array
+	 */
+	async updateTaskHistory(item: HistoryItem, options: { broadcast?: boolean } = {}): Promise<HistoryItem[]> {
+		const { broadcast = true } = options
 		const history = (this.getGlobalState("taskHistory") as HistoryItem[] | undefined) || []
 		const existingItemIndex = history.findIndex((h) => h.id === item.id)
+		const wasExisting = existingItemIndex !== -1
 
-		if (existingItemIndex !== -1) {
+		if (wasExisting) {
 			// Preserve existing metadata (e.g., delegation fields) unless explicitly overwritten.
 			// This prevents loss of status/awaitingChildId/delegatedToId when tasks are reopened,
 			// terminated, or when routine message persistence occurs.
@@ -2493,9 +2520,39 @@ export class ClineProvider
 		await this.updateGlobalState("taskHistory", history)
 		this.recentTasksCache = undefined
 
+		// Broadcast the updated history to the webview if requested.
+		// Prefer per-item updates to avoid repeatedly cloning/sending the full history.
+		if (broadcast && this.isViewLaunched) {
+			const updatedItem = wasExisting ? history[existingItemIndex] : item
+			await this.postMessageToWebview({ type: "taskHistoryItemUpdated", taskHistoryItem: updatedItem })
+		}
+
 		return history
 	}
 
+	/**
+	 * Broadcasts a task history update to the webview.
+	 * This sends a lightweight message with just the task history, rather than the full state.
+	 * @param history The task history to broadcast (if not provided, reads from global state)
+	 */
+	public async broadcastTaskHistoryUpdate(history?: HistoryItem[]): Promise<void> {
+		if (!this.isViewLaunched) {
+			return
+		}
+
+		const taskHistory = history ?? (this.getGlobalState("taskHistory") as HistoryItem[] | undefined) ?? []
+
+		// Sort and filter the history the same way as getStateToPostToWebview
+		const sortedHistory = taskHistory
+			.filter((item: HistoryItem) => item.ts && item.task)
+			.sort((a: HistoryItem, b: HistoryItem) => b.ts - a.ts)
+
+		await this.postMessageToWebview({
+			type: "taskHistoryUpdated",
+			taskHistory: sortedHistory,
+		})
+	}
+
 	// ContextProxy
 
 	// @deprecated - Use `ContextProxy#setValue` instead.

src/core/webview/__tests__/ClineProvider.flicker-free-cancel.spec.ts

@@ -150,6 +150,7 @@ describe("ClineProvider flicker-free cancel", () => {
 		})
 
 		provider.postStateToWebview = vi.fn().mockResolvedValue(undefined)
+		provider.postStateToWebviewWithoutTaskHistory = vi.fn().mockResolvedValue(undefined)
 		// Mock private method using any cast
 		;(provider as any).updateGlobalState = vi.fn().mockResolvedValue(undefined)
 		provider.activateProviderProfile = vi.fn().mockResolvedValue(undefined)