fix(history): prompt on workspace mismatch

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

@@ -19,7 +19,7 @@ vi.mock("../../../utils/safeWriteJson", () => ({
 }))
 
 // Import after mocks
-import { saveTaskMessages, readTaskMessages } from "../taskMessages"
+import { saveTaskMessages, readTaskMessages, updateTaskMessages } from "../taskMessages"
 import { formatErrorDetail } from "../readFileWithMissingRetry"
 
 let tmpBaseDir: string
@@ -119,6 +119,55 @@ describe("taskMessages.saveTaskMessages", () => {
 	})
 })
 
+describe("taskMessages.updateTaskMessages", () => {
+	it("keeps legacy same-timestamp identities distinct across removal and rollback", async () => {
+		const { safeWriteJson } =
+			await vi.importActual<typeof import("../../../utils/safeWriteJson")>("../../../utils/safeWriteJson")
+		const options = { taskId: "task-legacy-update", globalStoragePath: tmpBaseDir }
+		hoisted.safeWriteJsonMock.mockImplementationOnce(safeWriteJson)
+		await saveTaskMessages({ ...options, messages: [] })
+		await fs.writeFile(
+			path.join(tmpBaseDir, "tasks", options.taskId, "ui_messages.json"),
+			JSON.stringify([
+				{ ts: 1, type: "say", say: "checkpoint_saved", text: "checkpoint" },
+				{ ts: 1, type: "say", say: "text", text: "keep" },
+			]),
+		)
+		let removed: ClineMessage[] = []
+		hoisted.safeWriteJsonMock.mockImplementationOnce(safeWriteJson)
+		await updateTaskMessages({
+			...options,
+			update: (messages) => {
+				removed = messages.slice(0, 1)
+				return messages.slice(1)
+			},
+		})
+		hoisted.safeWriteJsonMock.mockImplementationOnce(safeWriteJson)
+		await saveTaskMessages({ ...options, messages: removed, merge: true })
+		const messages = await readTaskMessages(options)
+		expect(messages.map((message) => message.text).sort()).toEqual(["checkpoint", "keep"])
+		expect(new Set(messages.map((message) => message.messageId)).size).toBe(2)
+	})
+
+	it.each([null, "invalid", {}])("rejects a missing or invalid locked snapshot: %j", async (existing: unknown) => {
+		const { safeWriteJson } =
+			await vi.importActual<typeof import("../../../utils/safeWriteJson")>("../../../utils/safeWriteJson")
+		hoisted.safeWriteJsonMock.mockImplementationOnce(safeWriteJson)
+		const taskId = "task-invalid-update"
+		const taskDir = path.join(tmpBaseDir, "tasks", taskId)
+		await fs.mkdir(taskDir, { recursive: true })
+		const filePath = path.join(taskDir, "ui_messages.json")
+		if (existing !== null) await fs.writeFile(filePath, JSON.stringify(existing))
+		const update = vi.fn((messages: ClineMessage[]) => messages)
+		await expect(updateTaskMessages({ taskId, globalStoragePath: tmpBaseDir, update })).rejects.toMatchObject({
+			kind: "invalid",
+		})
+		expect(update).not.toHaveBeenCalled()
+		if (existing !== null) expect(JSON.parse(await fs.readFile(filePath, "utf8"))).toEqual(existing)
+		else await expect(fs.stat(filePath)).rejects.toMatchObject({ code: "ENOENT" })
+	})
+})
+
 describe("taskMessages.readTaskMessages", () => {
 	it("rejects invalid JSON without treating it as empty history", async () => {
 		const taskId = "task-corrupt-json"

src/core/task-persistence/taskMessages.ts

@@ -73,6 +73,24 @@
 	merge?: boolean
 }
 
+/** Update the current disk snapshot under the same lock used by every message writer. */
+export async function updateTaskMessages({
+	taskId,
+	globalStoragePath,
+	update,
+}: ReadTaskMessagesOptions & { update: (messages: ClineMessage[]) => ClineMessage[] }): Promise<void> {
+	const taskDir = await getTaskDirectoryPath(globalStoragePath, taskId)
+	const filePath = path.join(taskDir, GlobalFileNames.uiMessages)
+	await safeWriteJson(filePath, null, {
+		merge: (existing) => {
+			if (!Array.isArray(existing)) {
+				throw new TaskMessagesReadError("invalid", `Cannot update missing or invalid messages for ${taskId}`)
+			}
+			return ensureMessageIdentifiers(update(ensureMessageIdentifiers(existing)))
+		},
+	})
+}
+
 export async function saveTaskMessages({
 	messages,
 	taskId,

src/core/webview/ClineProvider.ts

@@ -101,8 +101,9 @@
 import { fileExistsAtPath } from "../../utils/fs"
 import { setTtsEnabled, setTtsSpeed } from "../../utils/tts"
 import { getWorkspaceGitInfo } from "../../utils/git"
-import { getWorkspacePath } from "../../utils/path"
+import { arePathsEqual, getWorkspacePath } from "../../utils/path"
 import { OrganizationAllowListViolationError } from "../../utils/errors"
+import { getTaskDirectoryPath } from "../../utils/storage"
 
 import { setPanel } from "../../activate/registerCommands"
 
@@ -131,7 +132,7 @@
 	interruptDelegatedChild,
 	LifecycleTransitionError,
 } from "../task-persistence"
-import { readTaskMessages } from "../task-persistence/taskMessages"
+import { readTaskMessages, updateTaskMessages } from "../task-persistence/taskMessages"
 import { getNonce } from "./getNonce"
 import { getUri } from "./getUri"
 import { omitOriginalContentFromExtensionMessage } from "./stripOriginalContent"
@@ -2430,12 +2431,184 @@
 		if (id !== this.getCurrentTask()?.taskId) {
 			// Non-current task.
 			const { historyItem } = await this.getTaskWithId(id)
-			await this.createTaskWithHistoryItem(historyItem) // Clears existing task.
+			const preparedHistoryItem = await this.prepareHistoryItemForResume(historyItem)
+			if (!preparedHistoryItem) {
+				return
+			}
+			await this.createTaskWithHistoryItem(preparedHistoryItem) // Clears existing task.
 		}
 
 		await this.postMessageToWebview({ type: "action", action: "chatButtonClicked" })
 	}
 
+	public async prepareHistoryItemForResume<T extends HistoryItem>(historyItem: T): Promise<T | undefined> {
+		const currentWorkspace = this.cwd
+		const originalWorkspace = historyItem.workspace
+
+		if (!currentWorkspace || !originalWorkspace || arePathsEqual(currentWorkspace, originalWorkspace)) {
+			return historyItem
+		}
+
+		// A live Task owns this history and would re-add checkpoint rows or rewrite its workspace after a reset.
+		if (this.isTaskLiveInAnyProvider(historyItem.id)) {
+			return historyItem
+		}
+
+		const useCurrentWorkspace = { title: "Use Current Workspace" }
+		const openOriginalWorkspace = { title: "Open Original Workspace" }
+		const selection = await vscode.window.showWarningMessage(
+			`This conversation was created in "${originalWorkspace}", but the current workspace is "${currentWorkspace}". ` +
+				"Choose where to continue. Using the current workspace resets checkpoints created in the original workspace.",
+			{ modal: true },
+			useCurrentWorkspace,
+			openOriginalWorkspace,
+		)
+
+		if (selection?.title === openOriginalWorkspace.title) {
+			await vscode.commands.executeCommand("vscode.openFolder", vscode.Uri.file(originalWorkspace), {
+				forceNewWindow: true,
+			})
+			return undefined
+		}
+
+		if (selection?.title !== useCurrentWorkspace.title) {
+			return undefined
+		}
+
+		// The modal has no timeout, so the task may have been opened elsewhere while it was shown.
+		if (this.isTaskLiveInAnyProvider(historyItem.id)) {
+			this.log(`[prepareHistoryItemForResume] Task ${historyItem.id} became live during workspace selection`)
+			return undefined
+		}
+
+		const updatedHistoryItem = { ...historyItem, workspace: currentWorkspace }
+		const persisted = await this.resetTaskCheckpointsForWorkspaceChange(historyItem, updatedHistoryItem)
+		// Resume from the record as persisted now, not the snapshot read before the prompt.
+		return { ...historyItem, ...persisted, workspace: currentWorkspace }
+	}
+
+	private isTaskLiveInAnyProvider(taskId: string): boolean {
+		return ClineProvider.getAllInstances().some((provider) => provider.taskRegistry.getById(taskId) !== undefined)
+	}
+
+	/**
+	 * Persist only `workspace`, read-modify-writing the stored record so fields that changed meanwhile
+	 * (status, pendingAction, ...) are never overwritten from a stale snapshot. With `expectedWorkspace`,
+	 * the stored record is left unchanged unless it still has that workspace.
+	 */
+	private async setTaskHistoryWorkspace(
+		historyItem: HistoryItem,
+		workspace: string | undefined,
+		expectedWorkspace?: string,
+	): Promise<HistoryItem | undefined> {
+		const taskId = historyItem.id
+		if (!this.taskHistoryStore.get(taskId)) {
+			// Legacy fallback before the store is initialized: there is no stored record to preserve.
+			if (expectedWorkspace !== undefined) return undefined
+			await this.updateTaskHistory({ ...historyItem, workspace })
+			return this.taskHistoryStore.get(taskId)
+		}
+
+		let changed = false
+		await this.taskHistoryStore.atomicReadAndUpdate(taskId, (current) => {
+			if (expectedWorkspace !== undefined && current.workspace !== expectedWorkspace) return current
+			changed = current.workspace !== workspace
+			return { ...current, workspace }
+		})
+		this.recentTasksCache = undefined
+		const updated = this.taskHistoryStore.get(taskId)
+		if (changed && updated && this.isViewLaunched) {
+			await this.postMessageToWebview({ type: "taskHistoryItemUpdated", taskHistoryItem: updated })
+		}
+		return updated
+	}
+
+	private async resetTaskCheckpointsForWorkspaceChange(
+		originalHistoryItem: HistoryItem,
+		updatedHistoryItem: HistoryItem,
+	): Promise<HistoryItem | undefined> {
+		const taskId = originalHistoryItem.id
+		const globalStoragePath = this.contextProxy.globalStorageUri.fsPath
+		let removedCheckpoints: ClineMessage[] = []
+		let persisted: HistoryItem | undefined
+		const taskDir = await getTaskDirectoryPath(globalStoragePath, taskId)
+		const checkpointsDir = path.join(taskDir, "checkpoints")
+		const checkpointBackupDir = path.join(taskDir, `checkpoints.workspace-change-${crypto.randomUUID()}`)
+		let checkpointDirectoryStaged = false
+
+		try {
+			await fs.rename(checkpointsDir, checkpointBackupDir)
+			checkpointDirectoryStaged = true
+		} catch (error) {
+			if (!(error instanceof Error && "code" in error && error.code === "ENOENT")) {
+				throw error
+			}
+		}
+
+		try {
+			await updateTaskMessages({
+				taskId,
+				globalStoragePath,
+				update: (messages) => {
+					removedCheckpoints = messages.filter(
+						(message) => message.type === "say" && message.say === "checkpoint_saved",
+					)
+					return messages.filter((message) => !removedCheckpoints.includes(message))
+				},
+			})
+			persisted = await this.setTaskHistoryWorkspace(originalHistoryItem, updatedHistoryItem.workspace)
+		} catch (error) {
+			if (removedCheckpoints.length > 0) {
+				try {
+					// Restore only the removed rows; never replace intervening message writes.
+					await saveTaskMessages({ messages: removedCheckpoints, taskId, globalStoragePath, merge: true })
+				} catch (rollbackError) {
+					this.log(
+						`[resetTaskCheckpointsForWorkspaceChange] Failed to restore messages for ${taskId}: ${rollbackError instanceof Error ? rollbackError.message : String(rollbackError)}`,
+					)
+				}
+			}
+			if (checkpointDirectoryStaged) {
+				try {
+					await fs.rename(checkpointBackupDir, checkpointsDir)
+				} catch (rollbackError) {
+					this.log(
+						`[resetTaskCheckpointsForWorkspaceChange] Failed to restore checkpoints for ${taskId} from ${checkpointBackupDir}: ${rollbackError instanceof Error ? rollbackError.message : String(rollbackError)}`,
+					)
+				}
+			}
+			try {
+				// Revert only the workspace, and only if no newer write has moved it again.
+				await this.setTaskHistoryWorkspace(
+					originalHistoryItem,
+					originalHistoryItem.workspace,
+					updatedHistoryItem.workspace,
+				)
+			} catch (rollbackError) {
+				this.log(
+					`[resetTaskCheckpointsForWorkspaceChange] Failed to restore history for ${taskId}: ${rollbackError instanceof Error ? rollbackError.message : String(rollbackError)}`,
+				)
+			}
+			throw error
+		}
+
+		if (checkpointDirectoryStaged) {
+			for (let attempt = 0; attempt < 3; attempt++) {
+				try {
+					await fs.rm(checkpointBackupDir, { recursive: true, force: true })
+					break
+				} catch (error) {
+					this.log(
+						`[resetTaskCheckpointsForWorkspaceChange] Failed to remove checkpoint backup ${checkpointBackupDir}: ${error instanceof Error ? error.message : String(error)}`,
+					)
+					if (attempt < 2) await delay(100)
+				}
+			}
+		}
+
+		return persisted
+	}
+
 	async exportTaskWithId(id: string) {
 		const { historyItem, apiConversationHistory } = await this.getTaskWithId(id)
 		const fileName = getTaskFileName(historyItem.ts)