feat: prevent file corruption from focus switching during active editing

- Add ActivityDetector utility to track user typing/editing activity
- Integrate activity detection into all file editing tools
- Wait for 2-second inactivity timeout before file operations
- Show warning dialog if user remains active after 10 seconds
- Enable PREVENT_FOCUS_DISRUPTION experiment by default
- Add comprehensive tests for activity detection

Fixes #8840

Author: roomote

src/core/tools/__tests__/insertContentTool.spec.ts

@@ -5,6 +5,7 @@ import type { MockedFunction } from "vitest"
 import { fileExistsAtPath } from "../../../utils/fs"
 import { ToolUse, ToolResponse } from "../../../shared/tools"
 import { insertContentTool } from "../insertContentTool"
+import { experiments } from "../../../shared/experiments"
 
 // Helper to normalize paths to POSIX format for cross-platform testing
 const toPosix = (filePath: string) => filePath.replace(/\\/g, "/")
@@ -23,6 +24,22 @@ vi.mock("../../../utils/fs", () => ({
 	fileExistsAtPath: vi.fn().mockResolvedValue(false),
 }))
 
+vi.mock("../../../shared/experiments", () => ({
+	experiments: {
+		isEnabled: vi.fn().mockReturnValue(false),
+	},
+	EXPERIMENT_IDS: {
+		PREVENT_FOCUS_DISRUPTION: "preventFocusDisruption",
+	},
+}))
+
+vi.mock("../../../utils/activity-detector", () => ({
+	getActivityDetector: vi.fn().mockReturnValue({
+		isUserActive: vi.fn().mockReturnValue(false),
+		waitForInactivity: vi.fn().mockResolvedValue(true),
+	}),
+}))
+
 vi.mock("../../prompts/responses", () => ({
 	formatResponse: {
 		toolError: vi.fn((msg) => `Error: ${msg}`),
@@ -64,6 +81,9 @@ describe("insertContentTool", () => {
 	beforeEach(() => {
 		vi.clearAllMocks()
 
+		// Mock experiments to be disabled by default for tests
+		vi.mocked(experiments).isEnabled.mockReturnValue(false)
+
 		mockedFileExistsAtPath.mockResolvedValue(true) // Assume file exists by default for insert
 		mockedFsReadFile.mockResolvedValue("") // Default empty file content
 

src/core/tools/__tests__/writeToFileTool.spec.ts

@@ -10,6 +10,7 @@ import { unescapeHtmlEntities } from "../../../utils/text-normalization"
 import { everyLineHasLineNumbers, stripLineNumbers } from "../../../integrations/misc/extract-text"
 import { ToolUse, ToolResponse } from "../../../shared/tools"
 import { writeToFileTool } from "../writeToFileTool"
+import { experiments } from "../../../shared/experiments"
 
 vi.mock("path", async () => {
 	const originalPath = await vi.importActual("path")
@@ -92,6 +93,15 @@ vi.mock("../../ignore/RooIgnoreController", () => ({
 	},
 }))
 
+vi.mock("../../../shared/experiments", () => ({
+	EXPERIMENT_IDS: {
+		PREVENT_FOCUS_DISRUPTION: "preventFocusDisruption",
+	},
+	experiments: {
+		isEnabled: vi.fn().mockReturnValue(false), // Default to disabled for tests
+	},
+}))
+
 describe("writeToFileTool", () => {
 	// Test data
 	const testFilePath = "test/file.txt"
@@ -119,6 +129,9 @@ describe("writeToFileTool", () => {
 	beforeEach(() => {
 		vi.clearAllMocks()
 
+		// Mock experiments to be disabled by default for tests
+		vi.mocked(experiments.isEnabled).mockReturnValue(false)
+
 		mockedPathResolve.mockReturnValue(absoluteFilePath)
 		mockedFileExistsAtPath.mockResolvedValue(false)
 		mockedDetectCodeOmission.mockReturnValue(false)

src/core/tools/applyDiffTool.ts

@@ -1,5 +1,6 @@
 import path from "path"
 import fs from "fs/promises"
+import * as vscode from "vscode"
 
 import { TelemetryService } from "@roo-code/telemetry"
 import { DEFAULT_WRITE_DELAY_MS } from "@roo-code/types"
@@ -13,6 +14,7 @@ import { fileExistsAtPath } from "../../utils/fs"
 import { RecordSource } from "../context-tracking/FileContextTrackerTypes"
 import { unescapeHtmlEntities } from "../../utils/text-normalization"
 import { EXPERIMENT_IDS, experiments } from "../../shared/experiments"
+import { getActivityDetector } from "../../utils/activity-detector"
 
 export async function applyDiffToolLegacy(
 	cline: Task,
@@ -154,6 +156,31 @@ export async function applyDiffToolLegacy(
 			const isWriteProtected = cline.rooProtectedController?.isWriteProtected(relPath) || false
 
 			if (isPreventFocusDisruptionEnabled) {
+				// Wait for user to become inactive before proceeding with file operations
+				const activityDetector = getActivityDetector()
+				if (activityDetector.isUserActive()) {
+					// Wait up to 10 seconds for user to become inactive
+					const becameInactive = await activityDetector.waitForInactivity(10000)
+
+					if (!becameInactive) {
+						// User is still active after timeout, ask for permission to proceed
+						const shouldProceed = await vscode.window.showWarningMessage(
+							"You appear to be actively editing. Would you like Roo Code to proceed with file changes anyway?",
+							"Proceed",
+							"Cancel",
+						)
+
+						if (shouldProceed !== "Proceed") {
+							pushToolResult(
+								formatResponse.toolError(
+									"File operation cancelled to avoid disrupting active editing.",
+								),
+							)
+							return
+						}
+					}
+				}
+
 				// Direct file write without diff view
 				const completeMessage = JSON.stringify({
 					...sharedMessageProps,

src/core/tools/insertContentTool.ts

@@ -1,6 +1,7 @@
 import delay from "delay"
 import fs from "fs/promises"
 import path from "path"
+import * as vscode from "vscode"
 
 import { getReadablePath } from "../../utils/path"
 import { Task } from "../task/Task"
@@ -12,6 +13,7 @@ import { fileExistsAtPath } from "../../utils/fs"
 import { insertGroups } from "../diff/insert-groups"
 import { DEFAULT_WRITE_DELAY_MS } from "@roo-code/types"
 import { EXPERIMENT_IDS, experiments } from "../../shared/experiments"
+import { getActivityDetector } from "../../utils/activity-detector"
 
 export async function insertContentTool(
 	cline: Task,
@@ -150,6 +152,30 @@ export async function insertContentTool(
 			await cline.diffViewProvider.open(relPath)
 			await cline.diffViewProvider.update(updatedContent, true)
 			cline.diffViewProvider.scrollToFirstDiff()
+		} else {
+			// Wait for user to become inactive before proceeding with file operations
+			const activityDetector = getActivityDetector()
+			if (activityDetector.isUserActive()) {
+				// Wait up to 10 seconds for user to become inactive
+				const becameInactive = await activityDetector.waitForInactivity(10000)
+
+				if (!becameInactive) {
+					// User is still active after timeout, ask for permission to proceed
+					const shouldProceed = await vscode.window.showWarningMessage(
+						"You appear to be actively editing. Would you like Roo Code to proceed with file changes anyway?",
+						"Proceed",
+						"Cancel",
+					)
+
+					if (shouldProceed !== "Proceed") {
+						pushToolResult(
+							formatResponse.toolError("File operation cancelled to avoid disrupting active editing."),
+						)
+						await cline.diffViewProvider.reset()
+						return
+					}
+				}
+			}
 		}
 
 		// Ask for approval (same for both flows)

src/core/tools/searchAndReplaceTool.ts

@@ -2,6 +2,7 @@
 import path from "path"
 import fs from "fs/promises"
 import delay from "delay"
+import * as vscode from "vscode"
 
 // Internal imports
 import { Task } from "../task/Task"
@@ -13,6 +14,7 @@ import { fileExistsAtPath } from "../../utils/fs"
 import { RecordSource } from "../context-tracking/FileContextTrackerTypes"
 import { DEFAULT_WRITE_DELAY_MS } from "@roo-code/types"
 import { EXPERIMENT_IDS, experiments } from "../../shared/experiments"
+import { getActivityDetector } from "../../utils/activity-detector"
 
 /**
  * Tool for performing search and replace operations on files
@@ -221,6 +223,30 @@ export async function searchAndReplaceTool(
 			await cline.diffViewProvider.open(validRelPath)
 			await cline.diffViewProvider.update(newContent, true)
 			cline.diffViewProvider.scrollToFirstDiff()
+		} else {
+			// Wait for user to become inactive before proceeding with file operations
+			const activityDetector = getActivityDetector()
+			if (activityDetector.isUserActive()) {
+				// Wait up to 10 seconds for user to become inactive
+				const becameInactive = await activityDetector.waitForInactivity(10000)
+
+				if (!becameInactive) {
+					// User is still active after timeout, ask for permission to proceed
+					const shouldProceed = await vscode.window.showWarningMessage(
+						"You appear to be actively editing. Would you like Roo Code to proceed with file changes anyway?",
+						"Proceed",
+						"Cancel",
+					)
+
+					if (shouldProceed !== "Proceed") {
+						pushToolResult(
+							formatResponse.toolError("File operation cancelled to avoid disrupting active editing."),
+						)
+						await cline.diffViewProvider.reset()
+						return
+					}
+				}
+			}
 		}
 
 		const didApprove = await askApproval("tool", completeMessage, undefined, isWriteProtected)

src/core/tools/writeToFileTool.ts

@@ -16,6 +16,7 @@ import { detectCodeOmission } from "../../integrations/editor/detect-omission"
 import { unescapeHtmlEntities } from "../../utils/text-normalization"
 import { DEFAULT_WRITE_DELAY_MS } from "@roo-code/types"
 import { EXPERIMENT_IDS, experiments } from "../../shared/experiments"
+import { getActivityDetector } from "../../utils/activity-detector"
 
 export async function writeToFileTool(
 	cline: Task,
@@ -172,6 +173,35 @@ export async function writeToFileTool(
 			)
 
 			if (isPreventFocusDisruptionEnabled) {
+				// Wait for user to become inactive before proceeding with file operations
+				const activityDetector = getActivityDetector()
+				if (activityDetector.isUserActive()) {
+					// Notify user that we're waiting for them to stop typing
+					await cline.say("text", "Waiting for you to finish typing before making file changes...")
+
+					// Wait up to 10 seconds for user to become inactive
+					const becameInactive = await activityDetector.waitForInactivity(10000)
+
+					if (!becameInactive) {
+						// User is still active after timeout, ask for permission to proceed
+						const shouldProceed = await vscode.window.showWarningMessage(
+							"You appear to be actively editing. Would you like Roo Code to proceed with file changes anyway?",
+							"Proceed",
+							"Cancel",
+						)
+
+						if (shouldProceed !== "Proceed") {
+							await cline.say("text", "File operation cancelled to avoid disrupting your work.")
+							pushToolResult(
+								formatResponse.toolError(
+									"File operation cancelled to avoid disrupting active editing.",
+								),
+							)
+							return
+						}
+					}
+				}
+
 				// Direct file write without diff view
 				// Check for code omissions before proceeding
 				if (detectCodeOmission(cline.diffViewProvider.originalContent || "", newContent, predictedLineCount)) {

src/shared/__tests__/experiments-preventFocusDisruption.spec.ts

@@ -7,24 +7,24 @@ describe("PREVENT_FOCUS_DISRUPTION experiment", () => {
 
 	it("should have PREVENT_FOCUS_DISRUPTION in experimentConfigsMap", () => {
 		expect(experimentConfigsMap.PREVENT_FOCUS_DISRUPTION).toBeDefined()
-		expect(experimentConfigsMap.PREVENT_FOCUS_DISRUPTION.enabled).toBe(false)
+		expect(experimentConfigsMap.PREVENT_FOCUS_DISRUPTION.enabled).toBe(true) // Enabled by default
 	})
 
 	it("should have PREVENT_FOCUS_DISRUPTION in experimentDefault", () => {
-		expect(experimentDefault.preventFocusDisruption).toBe(false)
+		expect(experimentDefault.preventFocusDisruption).toBe(true) // Enabled by default
 	})
 
 	it("should correctly check if PREVENT_FOCUS_DISRUPTION is enabled", () => {
-		// Test when experiment is disabled (default)
+		// Test when experiment is explicitly disabled
 		const disabledConfig = { preventFocusDisruption: false }
 		expect(experiments.isEnabled(disabledConfig, EXPERIMENT_IDS.PREVENT_FOCUS_DISRUPTION)).toBe(false)
 
-		// Test when experiment is enabled
+		// Test when experiment is explicitly enabled
 		const enabledConfig = { preventFocusDisruption: true }
 		expect(experiments.isEnabled(enabledConfig, EXPERIMENT_IDS.PREVENT_FOCUS_DISRUPTION)).toBe(true)
 
-		// Test when experiment is not in config (should use default)
+		// Test when experiment is not in config (should use default - true)
 		const emptyConfig = {}
-		expect(experiments.isEnabled(emptyConfig, EXPERIMENT_IDS.PREVENT_FOCUS_DISRUPTION)).toBe(false)
+		expect(experiments.isEnabled(emptyConfig, EXPERIMENT_IDS.PREVENT_FOCUS_DISRUPTION)).toBe(true)
 	})
 })

src/shared/experiments.ts

@@ -19,7 +19,7 @@ interface ExperimentConfig {
 export const experimentConfigsMap: Record<ExperimentKey, ExperimentConfig> = {
 	MULTI_FILE_APPLY_DIFF: { enabled: false },
 	POWER_STEERING: { enabled: false },
-	PREVENT_FOCUS_DISRUPTION: { enabled: false },
+	PREVENT_FOCUS_DISRUPTION: { enabled: true }, // Enabled by default to prevent file corruption
 	IMAGE_GENERATION: { enabled: false },
 	RUN_SLASH_COMMAND: { enabled: false },
 }