[Fix] Sidebar stuck on spinner while a large task history loads

src/core/task-persistence/TaskHistoryStore.ts

@@ -94,6 +94,12 @@ export class TaskHistoryStore {
 	 */
 	public readonly initialized: Promise<void>
 	private resolveInitialized!: () => void
+	private _isInitialized = false
+
+	/** True once the initial scan has finished, so reads no longer need to wait on `initialized`. */
+	get isInitialized(): boolean {
+		return this._isInitialized
+	}
 
 	/** Periodic reconciliation interval in milliseconds. */
 	private static readonly RECONCILE_INTERVAL_MS = 5 * 60 * 1000
@@ -140,6 +146,7 @@ export class TaskHistoryStore {
 			this.startPeriodicReconciliation()
 		} finally {
 			// Mark initialization as complete so callers awaiting `initialized` can proceed
+			this._isInitialized = true
 			this.resolveInitialized()
 		}
 	}

src/core/task-persistence/__tests__/TaskHistoryStore.spec.ts

@@ -53,6 +53,15 @@ describe("TaskHistoryStore", () => {
 	})
 
 	describe("initialize()", () => {
+		it("reports isInitialized only after the scan completes", async () => {
+			expect(store.isInitialized).toBe(false)
+
+			await store.initialize()
+
+			expect(store.isInitialized).toBe(true)
+			await expect(store.initialized).resolves.toBeUndefined()
+		})
+
 		it("initializes from empty state (no index, no task dirs)", async () => {
 			await store.initialize()
 			expect(store.getAll()).toEqual([])

src/core/webview/ClineProvider.ts

@@ -2716,8 +2716,11 @@ export class ClineProvider
 	}
 
 	async getStateToPostToWebview({ includeTaskHistory = true }: GetStateOptions = {}): Promise<ExtensionState> {
-		// Ensure the store is initialized before reading task history
-		await this.taskHistoryStore.initialized
+		// Only wait for the store when task history is requested, so a slow scan of a large
+		// history cannot keep the webview from receiving its first state.
+		if (includeTaskHistory) {
+			await this.taskHistoryStore.initialized
+		}
 
 		const {
 			apiConfiguration,

src/core/webview/__tests__/ClineProvider.spec.ts

@@ -2447,6 +2447,16 @@ describe("ClineProvider", () => {
 		expect(mockContext.globalState.update).toHaveBeenCalledWith("currentApiConfigName", "test-config")
 	})
 
+	it("builds state without task history while the task history store is still loading", async () => {
+		await provider.resolveWebviewView(mockWebviewView)
+		// A scan that never finishes must not block a state that omits task history.
+		Object.defineProperty(provider.taskHistoryStore, "initialized", { value: new Promise<void>(() => {}) })
+
+		const state = await provider.getStateToPostToWebview({ includeTaskHistory: false })
+
+		expect(state.taskHistory).toEqual([])
+	})
+
 	it("saves current config when switching to mode without config", async () => {
 		await provider.resolveWebviewView(mockWebviewView)
 		const messageHandler = (mockWebviewView.webview.onDidReceiveMessage as any).mock.calls[0][0]

src/core/webview/__tests__/webviewMessageHandler.spec.ts

@@ -128,6 +128,8 @@ const mockClineProvider = {
 	},
 	log: vi.fn(),
 	postStateToWebview: vi.fn(),
+	postStateToWebviewWithoutTaskHistory: vi.fn(),
+	taskHistoryStore: { isInitialized: true, initialized: Promise.resolve() },
 	resolveWebviewThemeFixtureProbe: vi.fn(),
 	getCurrentTask: vi.fn(),
 	getTaskWithId: vi.fn(),
@@ -3036,3 +3038,42 @@ describe("updateProfileModel", () => {
 		expect(updateProfileModel).not.toHaveBeenCalled()
 	})
 })
+
+describe("webviewMessageHandler - webviewDidLaunch task history", () => {
+	function setupLaunch(taskHistoryStore: { isInitialized: boolean; initialized: Promise<void> }) {
+		vi.mocked(mockClineProvider.customModesManager.getCustomModes).mockResolvedValue([])
+		const launchProvider = mockClineProvider as unknown as {
+			getMcpHub: ReturnType<typeof vi.fn>
+			providerSettingsManager: { listConfig: ReturnType<typeof vi.fn> }
+			taskHistoryStore: typeof taskHistoryStore
+		}
+		launchProvider.getMcpHub = vi.fn().mockReturnValue(undefined)
+		launchProvider.providerSettingsManager = { listConfig: vi.fn().mockResolvedValue(undefined) }
+		launchProvider.taskHistoryStore = taskHistoryStore
+		vi.mocked(mockClineProvider.postStateToWebview).mockClear()
+		vi.mocked(mockClineProvider.postStateToWebviewWithoutTaskHistory).mockClear()
+	}
+
+	it("posts the full state right away once task history is loaded", async () => {
+		setupLaunch({ isInitialized: true, initialized: Promise.resolve() })
+
+		await webviewMessageHandler(mockClineProvider, { type: "webviewDidLaunch" })
+
+		expect(mockClineProvider.postStateToWebview).toHaveBeenCalledTimes(1)
+		expect(mockClineProvider.postStateToWebviewWithoutTaskHistory).not.toHaveBeenCalled()
+	})
+
+	it("renders without waiting for a slow task history load, then posts the full state", async () => {
+		let finishLoading!: () => void
+		const initialized = new Promise<void>((resolve) => (finishLoading = resolve))
+		setupLaunch({ isInitialized: false, initialized })
+
+		await webviewMessageHandler(mockClineProvider, { type: "webviewDidLaunch" })
+
+		expect(mockClineProvider.postStateToWebviewWithoutTaskHistory).toHaveBeenCalledTimes(1)
+		expect(mockClineProvider.postStateToWebview).not.toHaveBeenCalled()
+
+		finishLoading()
+		await vi.waitFor(() => expect(mockClineProvider.postStateToWebview).toHaveBeenCalledTimes(1))
+	})
+})

src/core/webview/webviewMessageHandler.ts

@@ -596,7 +596,16 @@
 			const customModes = await provider.customModesManager.getCustomModes()
 			await updateGlobalState("customModes", customModes)
 
-			await provider.postStateToWebview()
+			if (provider.taskHistoryStore.isInitialized) {
+				await provider.postStateToWebview()
+			} else {
+				// A large task history can take a long time to scan. Render the UI now and
+				// send the full state, including history, once the scan completes.
+				await provider.postStateToWebviewWithoutTaskHistory()
+				void provider.taskHistoryStore.initialized
+					.then(() => provider.postStateToWebview())
+					.catch((err) => provider.log(`Task history state update error: ${err}`))
+			}
 			void provider.workspaceTracker
 				?.initializeFilePaths()
 				.catch((err) => provider.log(`Workspace initialization error: ${err}`)) // Don't await.