diff --git a/src/server/editorServices.ts b/src/server/editorServices.ts
index 858282315804e..9f3da93b674c8 100644
--- a/src/server/editorServices.ts
+++ b/src/server/editorServices.ts
@@ -27,6 +27,7 @@ import {
     Diagnostic,
     directorySeparator,
     DirectoryStructureHost,
+    DirectoryWatcherCallback,
     DocumentPosition,
     DocumentPositionMapper,
     DocumentRegistry,
@@ -37,6 +38,7 @@ import {
     FileExtensionInfo,
     fileExtensionIs,
     FileWatcher,
+    FileWatcherCallback,
     FileWatcherEventKind,
     find,
     flatMap,
@@ -127,6 +129,7 @@ import {
     version,
     WatchDirectoryFlags,
     WatchFactory,
+    WatchFactoryHost,
     WatchLogLevel,
     WatchOptions,
     WatchType,
@@ -193,6 +196,9 @@ export const ConfigFileDiagEvent = "configFileDiag";
 export const ProjectLanguageServiceStateEvent = "projectLanguageServiceState";
 export const ProjectInfoTelemetryEvent = "projectInfo";
 export const OpenFileInfoTelemetryEvent = "openFileInfo";
+export const CreateFileWatcherEvent: protocol.CreateFileWatcherEventName = "createFileWatcher";
+export const CreateDirectoryWatcherEvent: protocol.CreateDirectoryWatcherEventName = "createDirectoryWatcher";
+export const CloseFileWatcherEvent: protocol.CloseFileWatcherEventName = "closeFileWatcher";
 const ensureProjectForOpenFileSchedule = "*ensureProjectForOpenFiles*";
 
 export interface ProjectsUpdatedInBackgroundEvent {
@@ -320,6 +326,21 @@ export interface OpenFileInfo {
     readonly checkJs: boolean;
 }
 
+export interface CreateFileWatcherEvent {
+    readonly eventName: protocol.CreateFileWatcherEventName;
+    readonly data: protocol.CreateFileWatcherEventBody;
+}
+
+export interface CreateDirectoryWatcherEvent {
+    readonly eventName: protocol.CreateDirectoryWatcherEventName;
+    readonly data: protocol.CreateDirectoryWatcherEventBody;
+}
+
+export interface CloseFileWatcherEvent {
+    readonly eventName: protocol.CloseFileWatcherEventName;
+    readonly data: protocol.CloseFileWatcherEventBody;
+}
+
 export type ProjectServiceEvent =
     | LargeFileReferencedEvent
     | ProjectsUpdatedInBackgroundEvent
@@ -328,7 +349,10 @@ export type ProjectServiceEvent =
     | ConfigFileDiagEvent
     | ProjectLanguageServiceStateEvent
     | ProjectInfoTelemetryEvent
-    | OpenFileInfoTelemetryEvent;
+    | OpenFileInfoTelemetryEvent
+    | CreateFileWatcherEvent
+    | CreateDirectoryWatcherEvent
+    | CloseFileWatcherEvent;
 
 export type ProjectServiceEventHandler = (event: ProjectServiceEvent) => void;
 
@@ -583,6 +607,7 @@ export interface ProjectServiceOptions {
     useInferredProjectPerProjectRoot: boolean;
     typingsInstaller?: ITypingsInstaller;
     eventHandler?: ProjectServiceEventHandler;
+    canUseWatchEvents?: boolean;
     suppressDiagnosticEvents?: boolean;
     throttleWaitMilliseconds?: number;
     globalPlugins?: readonly string[];
@@ -857,6 +882,109 @@ function createProjectNameFactoryWithCounter(nameFactory: (counter: number) => s
     return () => nameFactory(nextId++);
 }
 
+interface HostWatcherMap<T> {
+    idToCallbacks: Map<number, Set<T>>;
+    pathToId: Map<Path, number>;
+}
+
+function getHostWatcherMap<T>(): HostWatcherMap<T> {
+    return { idToCallbacks: new Map(), pathToId: new Map() };
+}
+
+function createWatchFactoryHostUsingWatchEvents(service: ProjectService, canUseWatchEvents: boolean | undefined): WatchFactoryHost | undefined {
+    if (!canUseWatchEvents || !service.eventHandler || !service.session) return undefined;
+    const watchedFiles = getHostWatcherMap<FileWatcherCallback>();
+    const watchedDirectories = getHostWatcherMap<DirectoryWatcherCallback>();
+    const watchedDirectoriesRecursive = getHostWatcherMap<DirectoryWatcherCallback>();
+    let ids = 1;
+    service.session.addProtocolHandler(protocol.CommandTypes.WatchChange, req => {
+        onWatchChange((req as protocol.WatchChangeRequest).arguments);
+        return { responseRequired: false };
+    });
+    return {
+        watchFile,
+        watchDirectory,
+        getCurrentDirectory: () => service.host.getCurrentDirectory(),
+        useCaseSensitiveFileNames: service.host.useCaseSensitiveFileNames,
+    };
+    function watchFile(path: string, callback: FileWatcherCallback): FileWatcher {
+        return getOrCreateFileWatcher(
+            watchedFiles,
+            path,
+            callback,
+            id => ({ eventName: CreateFileWatcherEvent, data: { id, path } }),
+        );
+    }
+    function watchDirectory(path: string, callback: DirectoryWatcherCallback, recursive?: boolean): FileWatcher {
+        return getOrCreateFileWatcher(
+            recursive ? watchedDirectoriesRecursive : watchedDirectories,
+            path,
+            callback,
+            id => ({ eventName: CreateDirectoryWatcherEvent, data: { id, path, recursive: !!recursive } }),
+        );
+    }
+    function getOrCreateFileWatcher<T>(
+        { pathToId, idToCallbacks }: HostWatcherMap<T>,
+        path: string,
+        callback: T,
+        event: (id: number) => CreateFileWatcherEvent | CreateDirectoryWatcherEvent,
+    ) {
+        const key = service.toPath(path);
+        let id = pathToId.get(key);
+        if (!id) pathToId.set(key, id = ids++);
+        let callbacks = idToCallbacks.get(id);
+        if (!callbacks) {
+            idToCallbacks.set(id, callbacks = new Set());
+            // Add watcher
+            service.eventHandler!(event(id));
+        }
+        callbacks.add(callback);
+        return {
+            close() {
+                const callbacks = idToCallbacks.get(id!);
+                if (!callbacks?.delete(callback)) return;
+                if (callbacks.size) return;
+                idToCallbacks.delete(id!);
+                pathToId.delete(key);
+                service.eventHandler!({ eventName: CloseFileWatcherEvent, data: { id: id! } });
+            },
+        };
+    }
+    function onWatchChange({ id, path, eventType }: protocol.WatchChangeRequestArgs) {
+        // console.log(`typescript-vscode-watcher:: Invoke:: ${id}:: ${path}:: ${eventType}`);
+        onFileWatcherCallback(id, path, eventType);
+        onDirectoryWatcherCallback(watchedDirectories, id, path, eventType);
+        onDirectoryWatcherCallback(watchedDirectoriesRecursive, id, path, eventType);
+    }
+
+    function onFileWatcherCallback(
+        id: number,
+        eventPath: string,
+        eventType: "create" | "delete" | "update",
+    ) {
+        watchedFiles.idToCallbacks.get(id)?.forEach(callback => {
+            const eventKind = eventType === "create" ?
+                FileWatcherEventKind.Created :
+                eventType === "delete" ?
+                FileWatcherEventKind.Deleted :
+                FileWatcherEventKind.Changed;
+            callback(eventPath, eventKind);
+        });
+    }
+
+    function onDirectoryWatcherCallback(
+        { idToCallbacks }: HostWatcherMap<DirectoryWatcherCallback>,
+        id: number,
+        eventPath: string,
+        eventType: "create" | "delete" | "update",
+    ) {
+        if (eventType === "update") return;
+        idToCallbacks.get(id)?.forEach(callback => {
+            callback(eventPath);
+        });
+    }
+}
+
 export class ProjectService {
     /** @internal */
     readonly typingsCache: TypingsCache;
@@ -961,7 +1089,8 @@ export class ProjectService {
     public readonly typingsInstaller: ITypingsInstaller;
     private readonly globalCacheLocationDirectoryPath: Path | undefined;
     public readonly throttleWaitMilliseconds?: number;
-    private readonly eventHandler?: ProjectServiceEventHandler;
+    /** @internal */
+    readonly eventHandler?: ProjectServiceEventHandler;
     private readonly suppressDiagnosticEvents?: boolean;
 
     public readonly globalPlugins: readonly string[];
@@ -1065,7 +1194,12 @@ export class ProjectService {
                 watchFile: returnNoopFileWatcher,
                 watchDirectory: returnNoopFileWatcher,
             } :
-            getWatchFactory(this.host, watchLogLevel, log, getDetailWatchInfo);
+            getWatchFactory(
+                createWatchFactoryHostUsingWatchEvents(this, opts.canUseWatchEvents) || this.host,
+                watchLogLevel,
+                log,
+                getDetailWatchInfo,
+            );
         opts.incrementalVerifier?.(this);
     }
 
diff --git a/src/server/protocol.ts b/src/server/protocol.ts
index 6d06376d196eb..daa1738650b29 100644
--- a/src/server/protocol.ts
+++ b/src/server/protocol.ts
@@ -173,6 +173,7 @@ export const enum CommandTypes {
     ProvideCallHierarchyIncomingCalls = "provideCallHierarchyIncomingCalls",
     ProvideCallHierarchyOutgoingCalls = "provideCallHierarchyOutgoingCalls",
     ProvideInlayHints = "provideInlayHints",
+    WatchChange = "watchChange",
 }
 
 /**
@@ -1956,6 +1957,17 @@ export interface CloseRequest extends FileRequest {
     command: CommandTypes.Close;
 }
 
+export interface WatchChangeRequest extends Request {
+    command: CommandTypes.WatchChange;
+    arguments: WatchChangeRequestArgs;
+}
+
+export interface WatchChangeRequestArgs {
+    id: number;
+    path: string;
+    eventType: "create" | "delete" | "update";
+}
+
 /**
  * Request to obtain the list of files that should be regenerated if target file is recompiled.
  * NOTE: this us query-only operation and does not generate any output on disk.
@@ -3018,6 +3030,39 @@ export interface LargeFileReferencedEventBody {
     maxFileSize: number;
 }
 
+export type CreateFileWatcherEventName = "createFileWatcher";
+export interface CreateFileWatcherEvent extends Event {
+    readonly event: CreateFileWatcherEventName;
+    readonly body: CreateFileWatcherEventBody;
+}
+
+export interface CreateFileWatcherEventBody {
+    readonly id: number;
+    readonly path: string;
+}
+
+export type CreateDirectoryWatcherEventName = "createDirectoryWatcher";
+export interface CreateDirectoryWatcherEvent extends Event {
+    readonly event: CreateDirectoryWatcherEventName;
+    readonly body: CreateDirectoryWatcherEventBody;
+}
+
+export interface CreateDirectoryWatcherEventBody {
+    readonly id: number;
+    readonly path: string;
+    readonly recursive: boolean;
+}
+
+export type CloseFileWatcherEventName = "closeFileWatcher";
+export interface CloseFileWatcherEvent extends Event {
+    readonly event: CloseFileWatcherEventName;
+    readonly body: CloseFileWatcherEventBody;
+}
+
+export interface CloseFileWatcherEventBody {
+    readonly id: number;
+}
+
 /** @internal */
 export type AnyEvent =
     | RequestCompletedEvent
@@ -3029,7 +3074,10 @@ export type AnyEvent =
     | ProjectLoadingStartEvent
     | ProjectLoadingFinishEvent
     | SurveyReadyEvent
-    | LargeFileReferencedEvent;
+    | LargeFileReferencedEvent
+    | CreateFileWatcherEvent
+    | CreateDirectoryWatcherEvent
+    | CloseFileWatcherEvent;
 
 /**
  * Arguments for reload request.
diff --git a/src/server/session.ts b/src/server/session.ts
index 1da59c00e763a..42d1f52685103 100644
--- a/src/server/session.ts
+++ b/src/server/session.ts
@@ -139,11 +139,14 @@ import {
     WithMetadata,
 } from "./_namespaces/ts";
 import {
+    CloseFileWatcherEvent,
     ConfigFileDiagEvent,
     ConfiguredProject,
     convertFormatOptions,
     convertScriptKindName,
     convertUserPreferences,
+    CreateDirectoryWatcherEvent,
+    CreateFileWatcherEvent,
     EmitResult,
     emptyArray,
     Errors,
@@ -949,6 +952,7 @@ export interface SessionOptions {
      * If falsy, all events are suppressed.
      */
     canUseEvents: boolean;
+    canUseWatchEvents?: boolean;
     eventHandler?: ProjectServiceEventHandler;
     /** Has no effect if eventHandler is also specified. */
     suppressDiagnosticEvents?: boolean;
@@ -1026,6 +1030,7 @@ export class Session<TMessage = string> implements EventSender {
             typesMapLocation: opts.typesMapLocation,
             serverMode: opts.serverMode,
             session: this,
+            canUseWatchEvents: opts.canUseWatchEvents,
             incrementalVerifier: opts.incrementalVerifier,
         };
         this.projectService = new ProjectService(settings);
@@ -1080,39 +1085,37 @@ export class Session<TMessage = string> implements EventSender {
     private defaultEventHandler(event: ProjectServiceEvent) {
         switch (event.eventName) {
             case ProjectsUpdatedInBackgroundEvent:
-                const { openFiles } = event.data;
-                this.projectsUpdatedInBackgroundEvent(openFiles);
+                this.projectsUpdatedInBackgroundEvent(event.data.openFiles);
                 break;
             case ProjectLoadingStartEvent:
-                const { project, reason } = event.data;
-                this.event<protocol.ProjectLoadingStartEventBody>(
-                    { projectName: project.getProjectName(), reason },
-                    ProjectLoadingStartEvent,
-                );
+                this.event<protocol.ProjectLoadingStartEventBody>({
+                    projectName: event.data.project.getProjectName(),
+                    reason: event.data.reason,
+                }, event.eventName);
                 break;
             case ProjectLoadingFinishEvent:
-                const { project: finishProject } = event.data;
-                this.event<protocol.ProjectLoadingFinishEventBody>({ projectName: finishProject.getProjectName() }, ProjectLoadingFinishEvent);
+                this.event<protocol.ProjectLoadingFinishEventBody>({
+                    projectName: event.data.project.getProjectName(),
+                }, event.eventName);
                 break;
             case LargeFileReferencedEvent:
-                const { file, fileSize, maxFileSize } = event.data;
-                this.event<protocol.LargeFileReferencedEventBody>({ file, fileSize, maxFileSize }, LargeFileReferencedEvent);
+            case CreateFileWatcherEvent:
+            case CreateDirectoryWatcherEvent:
+            case CloseFileWatcherEvent:
+                this.event(event.data, event.eventName);
                 break;
             case ConfigFileDiagEvent:
-                const { triggerFile, configFileName: configFile, diagnostics } = event.data;
-                const bakedDiags = map(diagnostics, diagnostic => formatDiagnosticToProtocol(diagnostic, /*includeFileName*/ true));
                 this.event<protocol.ConfigFileDiagnosticEventBody>({
-                    triggerFile,
-                    configFile,
-                    diagnostics: bakedDiags,
-                }, ConfigFileDiagEvent);
+                    triggerFile: event.data.triggerFile,
+                    configFile: event.data.configFileName,
+                    diagnostics: map(event.data.diagnostics, diagnostic => formatDiagnosticToProtocol(diagnostic, /*includeFileName*/ true)),
+                }, event.eventName);
                 break;
             case ProjectLanguageServiceStateEvent: {
-                const eventName: protocol.ProjectLanguageServiceStateEventName = ProjectLanguageServiceStateEvent;
                 this.event<protocol.ProjectLanguageServiceStateEventBody>({
                     projectName: event.data.project.getProjectName(),
                     languageServiceEnabled: event.data.languageServiceEnabled,
-                }, eventName);
+                }, event.eventName);
                 break;
             }
             case ProjectInfoTelemetryEvent: {
diff --git a/src/testRunner/tests.ts b/src/testRunner/tests.ts
index 6c28643511d1f..2a5d2de2b383e 100644
--- a/src/testRunner/tests.ts
+++ b/src/testRunner/tests.ts
@@ -153,6 +153,7 @@ import "./unittests/tsserver/events/largeFileReferenced";
 import "./unittests/tsserver/events/projectLanguageServiceState";
 import "./unittests/tsserver/events/projectLoading";
 import "./unittests/tsserver/events/projectUpdatedInBackground";
+import "./unittests/tsserver/events/watchEvents";
 import "./unittests/tsserver/exportMapCache";
 import "./unittests/tsserver/extends";
 import "./unittests/tsserver/externalProjects";
diff --git a/src/testRunner/unittests/helpers/tsserver.ts b/src/testRunner/unittests/helpers/tsserver.ts
index 2c04526b55e7e..c02774d812319 100644
--- a/src/testRunner/unittests/helpers/tsserver.ts
+++ b/src/testRunner/unittests/helpers/tsserver.ts
@@ -567,7 +567,7 @@ export function createSession(host: TestServerHost, opts: Partial<TestSessionOpt
     return new TestSession({ ...sessionOptions, ...opts });
 }
 
-export function createSessionWithCustomEventHandler(host: TestServerHost, opts?: Partial<TestSessionOptions>) {
+export function createSessionWithCustomEventHandler(host: TestServerHost, opts?: Partial<TestSessionOptions>, customAction?: (event: ts.server.ProjectServiceEvent) => void) {
     const session = createSession(host, { eventHandler, logger: createLoggerWithInMemoryLogs(host), ...opts });
     return session;
     function eventHandler(event: ts.server.ProjectServiceEvent) {
@@ -578,6 +578,9 @@ export function createSessionWithCustomEventHandler(host: TestServerHost, opts?:
             case ts.server.LargeFileReferencedEvent:
             case ts.server.ProjectInfoTelemetryEvent:
             case ts.server.OpenFileInfoTelemetryEvent:
+            case ts.server.CreateFileWatcherEvent:
+            case ts.server.CreateDirectoryWatcherEvent:
+            case ts.server.CloseFileWatcherEvent:
                 break;
             // Convert project to project name
             case ts.server.ProjectLoadingStartEvent:
@@ -593,6 +596,7 @@ export function createSessionWithCustomEventHandler(host: TestServerHost, opts?:
                 ts.Debug.assertNever(event);
         }
         session.event(data, `CustomHandler::${event.eventName}`);
+        customAction?.(event);
     }
 }
 
diff --git a/src/testRunner/unittests/helpers/virtualFileSystemWithWatch.ts b/src/testRunner/unittests/helpers/virtualFileSystemWithWatch.ts
index eb96c9504e475..74d35ba8742c1 100644
--- a/src/testRunner/unittests/helpers/virtualFileSystemWithWatch.ts
+++ b/src/testRunner/unittests/helpers/virtualFileSystemWithWatch.ts
@@ -623,7 +623,7 @@ export class TestServerHost implements server.ServerHost, FormatDiagnosticsHost,
         this.removeFileOrFolder(currentEntry);
     }
 
-    private hasWatchChanges?: boolean;
+    hasWatchChanges?: boolean;
     private createWatcher<T>(map: MultiMap<Path, T>, path: Path, callback: T): FileWatcher {
         this.hasWatchChanges = true;
         map.add(path, callback);
@@ -1115,7 +1115,7 @@ function diffFsEntry(baseline: string[], oldFsEntry: FSEntry | undefined, newFsE
     }
 }
 
-function serializeMultiMap<T>(baseline: string[], caption: string, multiMap: MultiMap<string, T>, serialized: Map<string, T[]> | undefined) {
+export function serializeMultiMap<T>(baseline: string[], caption: string, multiMap: MultiMap<string, T>, serialized: Map<string, T[]> | undefined) {
     let hasChange = diffMap(baseline, caption, multiMap, serialized, /*deleted*/ false);
     hasChange = diffMap(baseline, caption, serialized, multiMap, /*deleted*/ true) || hasChange;
     if (hasChange) {
diff --git a/src/testRunner/unittests/tsserver/events/watchEvents.ts b/src/testRunner/unittests/tsserver/events/watchEvents.ts
new file mode 100644
index 0000000000000..8c28c946480f0
--- /dev/null
+++ b/src/testRunner/unittests/tsserver/events/watchEvents.ts
@@ -0,0 +1,197 @@
+import * as ts from "../../../_namespaces/ts";
+import {
+    baselineTsserverLogs,
+    closeFilesForSession,
+    createLoggerWithInMemoryLogs,
+    createSession,
+    createSessionWithCustomEventHandler,
+    Logger,
+    openFilesForSession,
+    TestSession,
+} from "../../helpers/tsserver";
+import {
+    createServerHost,
+    libFile,
+    serializeMultiMap,
+    TestServerHost,
+} from "../../helpers/virtualFileSystemWithWatch";
+
+describe("unittests:: tsserver:: events:: watchEvents", () => {
+    interface TestServerHostWithCustomWatch extends TestServerHost {
+        factoryData: {
+            watchedFiles: ts.MultiMap<string, ts.server.protocol.CreateFileWatcherEventBody>;
+            watchedDirectories: ts.MultiMap<string, ts.server.protocol.CreateDirectoryWatcherEventBody>;
+            watchedDirectoriesRecursive: ts.MultiMap<string, ts.server.protocol.CreateDirectoryWatcherEventBody>;
+            watchFile(data: ts.server.protocol.CreateFileWatcherEventBody): void;
+            watchDirectory(data: ts.server.protocol.CreateDirectoryWatcherEventBody): void;
+            closeWatcher(data: ts.server.protocol.CloseFileWatcherEventBody): void;
+        };
+    }
+
+    function createTestServerHostWithCustomWatch(
+        logger: Logger,
+    ) {
+        const idToClose = new Map<number, () => void>();
+        let serializedWatchedFiles: Map<string, ts.server.protocol.CreateFileWatcherEventBody[]> | undefined;
+        let serializedWatchedDirectories: Map<string, ts.server.protocol.CreateDirectoryWatcherEventBody[]> | undefined;
+        let serializedWatchedDirectoriesRecursive: Map<string, ts.server.protocol.CreateDirectoryWatcherEventBody[]> | undefined;
+        const host = logger.host as TestServerHostWithCustomWatch;
+        const originalSerializeWatches = host.serializeWatches;
+        host.serializeWatches = serializeWatches;
+        host.factoryData = {
+            watchedFiles: ts.createMultiMap(),
+            watchedDirectories: ts.createMultiMap(),
+            watchedDirectoriesRecursive: ts.createMultiMap(),
+            watchFile,
+            watchDirectory,
+            closeWatcher,
+        };
+        return host;
+
+        function watchFile(data: ts.server.protocol.CreateFileWatcherEventBody) {
+            logger.log(`Custom watchFile: ${data.id}: ${data.path}`);
+            ts.Debug.assert(!idToClose.has(data.id));
+            host.factoryData.watchedFiles.add(data.path, data);
+            host.hasWatchChanges = true;
+            idToClose.set(data.id, () => {
+                logger.log(`Custom watchFile:: Close:: ${data.id}: ${data.path}`);
+                host.factoryData.watchedFiles.remove(data.path, data);
+            });
+        }
+
+        function watchDirectory(data: ts.server.protocol.CreateDirectoryWatcherEventBody) {
+            logger.log(`Custom watchDirectory: ${data.id}: ${data.path} ${data.recursive}`);
+            ts.Debug.assert(!idToClose.has(data.id));
+            (data.recursive ? host.factoryData.watchedDirectoriesRecursive : host.factoryData.watchedDirectories).add(data.path, data);
+            host.hasWatchChanges = true;
+            idToClose.set(data.id, () => {
+                logger.log(`Custom watchDirectory:: Close:: ${data.id}: ${data.path} ${data.recursive}`);
+                (data.recursive ? host.factoryData.watchedDirectoriesRecursive : host.factoryData.watchedDirectories).remove(data.path, data);
+            });
+        }
+
+        function closeWatcher(data: ts.server.protocol.CloseFileWatcherEventBody) {
+            const close = idToClose.get(data.id);
+            if (close) {
+                idToClose.delete(data.id);
+                host.hasWatchChanges = true;
+                close();
+            }
+        }
+
+        function serializeWatches(baseline: string[] = []) {
+            const hasWatchChanges = host.hasWatchChanges;
+            originalSerializeWatches.call(host, baseline);
+            if (!hasWatchChanges) return baseline;
+            serializedWatchedFiles = serializeMultiMap(baseline, `Custom WatchedFiles`, host.factoryData.watchedFiles, serializedWatchedFiles);
+            serializedWatchedDirectories = serializeMultiMap(baseline, `Custom WatchedDirectories:Recursive`, host.factoryData.watchedDirectoriesRecursive, serializedWatchedDirectories);
+            serializedWatchedDirectoriesRecursive = serializeMultiMap(baseline, `Custom WatchedDirectories`, host.factoryData.watchedDirectories, serializedWatchedDirectoriesRecursive);
+            return baseline;
+        }
+    }
+
+    function updateFileOnHost(session: TestSession, file: string, log: string) {
+        // Change b.ts
+        session.logger.log(log);
+        session.testhost.writeFile(file, session.testhost.readFile("/user/username/projects/myproject/a.ts")!);
+        session.testhost.runQueuedTimeoutCallbacks();
+    }
+
+    function addFile(session: TestSession, path: string) {
+        updateFileOnHost(session, path, "Add file");
+        session.logger.log("Custom watch");
+        (session.logger.host as TestServerHostWithCustomWatch).factoryData.watchedDirectoriesRecursive.get("/user/username/projects/myproject")?.forEach(data =>
+            session.executeCommandSeq<ts.server.protocol.WatchChangeRequest>({
+                command: ts.server.protocol.CommandTypes.WatchChange,
+                arguments: { id: data.id, path, eventType: "create" },
+            })
+        );
+        session.testhost.runQueuedTimeoutCallbacks();
+    }
+
+    function changeFile(session: TestSession, path: string) {
+        updateFileOnHost(session, path, "Change File");
+        session.logger.log("Custom watch");
+        (session.logger.host as TestServerHostWithCustomWatch).factoryData.watchedFiles.get(path)?.forEach(data =>
+            session.executeCommandSeq<ts.server.protocol.WatchChangeRequest>({
+                command: ts.server.protocol.CommandTypes.WatchChange,
+                arguments: { id: data.id, path, eventType: "update" },
+            })
+        );
+        session.testhost.runQueuedTimeoutCallbacks();
+    }
+
+    function setup() {
+        const inputHost = createServerHost({
+            "/user/username/projects/myproject/tsconfig.json": "{}",
+            "/user/username/projects/myproject/a.ts": `export class a { prop = "hello"; foo() { return this.prop; } }`,
+            "/user/username/projects/myproject/b.ts": `export class b { prop = "hello"; foo() { return this.prop; } }`,
+            [libFile.path]: libFile.content,
+        });
+        const logger = createLoggerWithInMemoryLogs(inputHost);
+        const host = createTestServerHostWithCustomWatch(logger);
+        return { host, logger };
+    }
+
+    it("canUseWatchEvents", () => {
+        const { host, logger } = setup();
+        const session = createSessionWithCustomEventHandler(logger.host!, { canUseWatchEvents: true, logger }, handleWatchEvents);
+        openFilesForSession(["/user/username/projects/myproject/a.ts"], session);
+
+        // Directory watcher
+        addFile(session, "/user/username/projects/myproject/c.ts");
+
+        // File Watcher
+        changeFile(session, "/user/username/projects/myproject/b.ts");
+
+        // Close watcher
+        openFilesForSession(["/user/username/projects/myproject/b.ts"], session);
+
+        // Re watch
+        closeFilesForSession(["/user/username/projects/myproject/b.ts"], session);
+
+        baselineTsserverLogs("events/watchEvents", `canUseWatchEvents`, session);
+        function handleWatchEvents(event: ts.server.ProjectServiceEvent) {
+            switch (event.eventName) {
+                case ts.server.CreateFileWatcherEvent:
+                    host.factoryData.watchFile(event.data);
+                    break;
+                case ts.server.CreateDirectoryWatcherEvent:
+                    host.factoryData.watchDirectory(event.data);
+                    break;
+                case ts.server.CloseFileWatcherEvent:
+                    host.factoryData.closeWatcher(event.data);
+                    break;
+                default:
+                    break;
+            }
+        }
+    });
+
+    it("canUseWatchEvents without canUseEvents", () => {
+        const { logger } = setup();
+        const session = createSession(logger.host!, { canUseEvents: false, logger });
+        openFilesForSession(["/user/username/projects/myproject/a.ts"], session);
+
+        // Directory watcher
+        addFile(session, "/user/username/projects/myproject/c.ts");
+
+        // File Watcher
+        changeFile(session, "/user/username/projects/myproject/b.ts");
+
+        // Close watcher
+        openFilesForSession(["/user/username/projects/myproject/b.ts"], session);
+
+        // Re watch
+        closeFilesForSession(["/user/username/projects/myproject/b.ts"], session);
+
+        // Shouldnt have watch change request
+        logger.msg = (s, type) => logger.info(`${type}:: ${s}`);
+        session.executeCommandSeq<ts.server.protocol.WatchChangeRequest>({
+            command: ts.server.protocol.CommandTypes.WatchChange,
+            arguments: { id: 1, path: "/user/username/projects/myproject/b.ts", eventType: "update" },
+        });
+
+        baselineTsserverLogs("events/watchEvents", `canUseWatchEvents without canUseEvents`, session);
+    });
+});
diff --git a/src/tsserver/common.ts b/src/tsserver/common.ts
index 0d55e49e2f13e..c21f3ba1dfd5c 100644
--- a/src/tsserver/common.ts
+++ b/src/tsserver/common.ts
@@ -30,6 +30,7 @@ export interface StartSessionOptions {
     useInferredProjectPerProjectRoot: SessionOptions["useInferredProjectPerProjectRoot"];
     suppressDiagnosticEvents: SessionOptions["suppressDiagnosticEvents"];
     noGetErrOnBackgroundUpdate: SessionOptions["noGetErrOnBackgroundUpdate"];
+    canUseWatchEvents: SessionOptions["canUseWatchEvents"];
     serverMode: SessionOptions["serverMode"];
 }
 
diff --git a/src/tsserver/server.ts b/src/tsserver/server.ts
index 9ee38169e0057..e30bdafd3c4a1 100644
--- a/src/tsserver/server.ts
+++ b/src/tsserver/server.ts
@@ -57,6 +57,7 @@ function start({ args, logger, cancellationToken, serverMode, unknownServerMode,
             useInferredProjectPerProjectRoot: hasArgument("--useInferredProjectPerProjectRoot"),
             suppressDiagnosticEvents: hasArgument("--suppressDiagnosticEvents"),
             noGetErrOnBackgroundUpdate: hasArgument("--noGetErrOnBackgroundUpdate"),
+            canUseWatchEvents: hasArgument("--canUseWatchEvents"),
             serverMode,
         },
         logger,
diff --git a/tests/baselines/reference/api/typescript.d.ts b/tests/baselines/reference/api/typescript.d.ts
index 88ce1a5067df1..98f1b33000391 100644
--- a/tests/baselines/reference/api/typescript.d.ts
+++ b/tests/baselines/reference/api/typescript.d.ts
@@ -171,6 +171,7 @@ declare namespace ts {
                 ProvideCallHierarchyIncomingCalls = "provideCallHierarchyIncomingCalls",
                 ProvideCallHierarchyOutgoingCalls = "provideCallHierarchyOutgoingCalls",
                 ProvideInlayHints = "provideInlayHints",
+                WatchChange = "watchChange",
             }
             /**
              * A TypeScript Server message
@@ -1504,6 +1505,15 @@ declare namespace ts {
             interface CloseRequest extends FileRequest {
                 command: CommandTypes.Close;
             }
+            interface WatchChangeRequest extends Request {
+                command: CommandTypes.WatchChange;
+                arguments: WatchChangeRequestArgs;
+            }
+            interface WatchChangeRequestArgs {
+                id: number;
+                path: string;
+                eventType: "create" | "delete" | "update";
+            }
             /**
              * Request to obtain the list of files that should be regenerated if target file is recompiled.
              * NOTE: this us query-only operation and does not generate any output on disk.
@@ -2421,6 +2431,33 @@ declare namespace ts {
                  */
                 maxFileSize: number;
             }
+            type CreateFileWatcherEventName = "createFileWatcher";
+            interface CreateFileWatcherEvent extends Event {
+                readonly event: CreateFileWatcherEventName;
+                readonly body: CreateFileWatcherEventBody;
+            }
+            interface CreateFileWatcherEventBody {
+                readonly id: number;
+                readonly path: string;
+            }
+            type CreateDirectoryWatcherEventName = "createDirectoryWatcher";
+            interface CreateDirectoryWatcherEvent extends Event {
+                readonly event: CreateDirectoryWatcherEventName;
+                readonly body: CreateDirectoryWatcherEventBody;
+            }
+            interface CreateDirectoryWatcherEventBody {
+                readonly id: number;
+                readonly path: string;
+                readonly recursive: boolean;
+            }
+            type CloseFileWatcherEventName = "closeFileWatcher";
+            interface CloseFileWatcherEvent extends Event {
+                readonly event: CloseFileWatcherEventName;
+                readonly body: CloseFileWatcherEventBody;
+            }
+            interface CloseFileWatcherEventBody {
+                readonly id: number;
+            }
             /**
              * Arguments for reload request.
              */
@@ -3528,6 +3565,21 @@ declare namespace ts {
             readonly eventName: typeof OpenFileInfoTelemetryEvent;
             readonly data: OpenFileInfoTelemetryEventData;
         }
+        const CreateFileWatcherEvent: protocol.CreateFileWatcherEventName;
+        interface CreateFileWatcherEvent {
+            readonly eventName: protocol.CreateFileWatcherEventName;
+            readonly data: protocol.CreateFileWatcherEventBody;
+        }
+        const CreateDirectoryWatcherEvent: protocol.CreateDirectoryWatcherEventName;
+        interface CreateDirectoryWatcherEvent {
+            readonly eventName: protocol.CreateDirectoryWatcherEventName;
+            readonly data: protocol.CreateDirectoryWatcherEventBody;
+        }
+        const CloseFileWatcherEvent: protocol.CloseFileWatcherEventName;
+        interface CloseFileWatcherEvent {
+            readonly eventName: protocol.CloseFileWatcherEventName;
+            readonly data: protocol.CloseFileWatcherEventBody;
+        }
         interface ProjectInfoTelemetryEventData {
             /** Cryptographically secure hash of project file location. */
             readonly projectId: string;
@@ -3575,7 +3627,7 @@ declare namespace ts {
         interface OpenFileInfo {
             readonly checkJs: boolean;
         }
-        type ProjectServiceEvent = LargeFileReferencedEvent | ProjectsUpdatedInBackgroundEvent | ProjectLoadingStartEvent | ProjectLoadingFinishEvent | ConfigFileDiagEvent | ProjectLanguageServiceStateEvent | ProjectInfoTelemetryEvent | OpenFileInfoTelemetryEvent;
+        type ProjectServiceEvent = LargeFileReferencedEvent | ProjectsUpdatedInBackgroundEvent | ProjectLoadingStartEvent | ProjectLoadingFinishEvent | ConfigFileDiagEvent | ProjectLanguageServiceStateEvent | ProjectInfoTelemetryEvent | OpenFileInfoTelemetryEvent | CreateFileWatcherEvent | CreateDirectoryWatcherEvent | CloseFileWatcherEvent;
         type ProjectServiceEventHandler = (event: ProjectServiceEvent) => void;
         interface SafeList {
             [name: string]: {
@@ -3609,6 +3661,7 @@ declare namespace ts {
             useInferredProjectPerProjectRoot: boolean;
             typingsInstaller?: ITypingsInstaller;
             eventHandler?: ProjectServiceEventHandler;
+            canUseWatchEvents?: boolean;
             suppressDiagnosticEvents?: boolean;
             throttleWaitMilliseconds?: number;
             globalPlugins?: readonly string[];
@@ -3680,7 +3733,6 @@ declare namespace ts {
             readonly typingsInstaller: ITypingsInstaller;
             private readonly globalCacheLocationDirectoryPath;
             readonly throttleWaitMilliseconds?: number;
-            private readonly eventHandler?;
             private readonly suppressDiagnosticEvents?;
             readonly globalPlugins: readonly string[];
             readonly pluginProbeLocations: readonly string[];
@@ -3894,6 +3946,7 @@ declare namespace ts {
              * If falsy, all events are suppressed.
              */
             canUseEvents: boolean;
+            canUseWatchEvents?: boolean;
             eventHandler?: ProjectServiceEventHandler;
             /** Has no effect if eventHandler is also specified. */
             suppressDiagnosticEvents?: boolean;
diff --git a/tests/baselines/reference/tsserver/events/watchEvents/canUseWatchEvents-without-canUseEvents.js b/tests/baselines/reference/tsserver/events/watchEvents/canUseWatchEvents-without-canUseEvents.js
new file mode 100644
index 0000000000000..4e9b6ceeb3f8d
--- /dev/null
+++ b/tests/baselines/reference/tsserver/events/watchEvents/canUseWatchEvents-without-canUseEvents.js
@@ -0,0 +1,357 @@
+currentDirectory:: / useCaseSensitiveFileNames: false
+Info seq  [hh:mm:ss:mss] Provided types map file "/a/lib/typesMap.json" doesn't exist
+Before request
+//// [/user/username/projects/myproject/tsconfig.json]
+{}
+
+//// [/user/username/projects/myproject/a.ts]
+export class a { prop = "hello"; foo() { return this.prop; } }
+
+//// [/user/username/projects/myproject/b.ts]
+export class b { prop = "hello"; foo() { return this.prop; } }
+
+//// [/a/lib/lib.d.ts]
+/// <reference no-default-lib="true"/>
+interface Boolean {}
+interface Function {}
+interface CallableFunction {}
+interface NewableFunction {}
+interface IArguments {}
+interface Number { toExponential: any; }
+interface Object {}
+interface RegExp {}
+interface String { charAt: any; }
+interface Array<T> { length: number; [n: number]: T; }
+
+
+Info seq  [hh:mm:ss:mss] request:
+    {
+      "command": "open",
+      "arguments": {
+        "file": "/user/username/projects/myproject/a.ts"
+      },
+      "seq": 1,
+      "type": "request"
+    }
+Info seq  [hh:mm:ss:mss] Search path: /user/username/projects/myproject
+Info seq  [hh:mm:ss:mss] For info: /user/username/projects/myproject/a.ts :: Config file name: /user/username/projects/myproject/tsconfig.json
+Info seq  [hh:mm:ss:mss] Creating configuration project /user/username/projects/myproject/tsconfig.json
+Info seq  [hh:mm:ss:mss] FileWatcher:: Added:: WatchInfo: /user/username/projects/myproject/tsconfig.json 2000 undefined Project: /user/username/projects/myproject/tsconfig.json WatchType: Config file
+Info seq  [hh:mm:ss:mss] Config: /user/username/projects/myproject/tsconfig.json : {
+ "rootNames": [
+  "/user/username/projects/myproject/a.ts",
+  "/user/username/projects/myproject/b.ts"
+ ],
+ "options": {
+  "configFilePath": "/user/username/projects/myproject/tsconfig.json"
+ }
+}
+Info seq  [hh:mm:ss:mss] DirectoryWatcher:: Added:: WatchInfo: /user/username/projects/myproject 1 undefined Config: /user/username/projects/myproject/tsconfig.json WatchType: Wild card directory
+Info seq  [hh:mm:ss:mss] Elapsed:: *ms DirectoryWatcher:: Added:: WatchInfo: /user/username/projects/myproject 1 undefined Config: /user/username/projects/myproject/tsconfig.json WatchType: Wild card directory
+Info seq  [hh:mm:ss:mss] FileWatcher:: Added:: WatchInfo: /user/username/projects/myproject/b.ts 500 undefined WatchType: Closed Script info
+Info seq  [hh:mm:ss:mss] Starting updateGraphWorker: Project: /user/username/projects/myproject/tsconfig.json
+Info seq  [hh:mm:ss:mss] FileWatcher:: Added:: WatchInfo: /a/lib/lib.d.ts 500 undefined WatchType: Closed Script info
+Info seq  [hh:mm:ss:mss] DirectoryWatcher:: Added:: WatchInfo: /user/username/projects/myproject/node_modules/@types 1 undefined Project: /user/username/projects/myproject/tsconfig.json WatchType: Type roots
+Info seq  [hh:mm:ss:mss] Elapsed:: *ms DirectoryWatcher:: Added:: WatchInfo: /user/username/projects/myproject/node_modules/@types 1 undefined Project: /user/username/projects/myproject/tsconfig.json WatchType: Type roots
+Info seq  [hh:mm:ss:mss] DirectoryWatcher:: Added:: WatchInfo: /user/username/projects/node_modules/@types 1 undefined Project: /user/username/projects/myproject/tsconfig.json WatchType: Type roots
+Info seq  [hh:mm:ss:mss] Elapsed:: *ms DirectoryWatcher:: Added:: WatchInfo: /user/username/projects/node_modules/@types 1 undefined Project: /user/username/projects/myproject/tsconfig.json WatchType: Type roots
+Info seq  [hh:mm:ss:mss] Finishing updateGraphWorker: Project: /user/username/projects/myproject/tsconfig.json Version: 1 structureChanged: true structureIsReused:: Not Elapsed:: *ms
+Info seq  [hh:mm:ss:mss] Project '/user/username/projects/myproject/tsconfig.json' (Configured)
+Info seq  [hh:mm:ss:mss] 	Files (3)
+	/a/lib/lib.d.ts Text-1 "/// <reference no-default-lib=\"true\"/>\ninterface Boolean {}\ninterface Function {}\ninterface CallableFunction {}\ninterface NewableFunction {}\ninterface IArguments {}\ninterface Number { toExponential: any; }\ninterface Object {}\ninterface RegExp {}\ninterface String { charAt: any; }\ninterface Array<T> { length: number; [n: number]: T; }"
+	/user/username/projects/myproject/a.ts SVC-1-0 "export class a { prop = \"hello\"; foo() { return this.prop; } }"
+	/user/username/projects/myproject/b.ts Text-1 "export class b { prop = \"hello\"; foo() { return this.prop; } }"
+
+
+	../../../../a/lib/lib.d.ts
+	  Default library for target 'es5'
+	a.ts
+	  Matched by default include pattern '**/*'
+	b.ts
+	  Matched by default include pattern '**/*'
+
+Info seq  [hh:mm:ss:mss] -----------------------------------------------
+Info seq  [hh:mm:ss:mss] Project '/user/username/projects/myproject/tsconfig.json' (Configured)
+Info seq  [hh:mm:ss:mss] 	Files (3)
+
+Info seq  [hh:mm:ss:mss] -----------------------------------------------
+Info seq  [hh:mm:ss:mss] Open files: 
+Info seq  [hh:mm:ss:mss] 	FileName: /user/username/projects/myproject/a.ts ProjectRootPath: undefined
+Info seq  [hh:mm:ss:mss] 		Projects: /user/username/projects/myproject/tsconfig.json
+Info seq  [hh:mm:ss:mss] response:
+    {
+      "responseRequired": false
+    }
+After request
+
+PolledWatches::
+/user/username/projects/myproject/node_modules/@types: *new*
+  {"pollingInterval":500}
+/user/username/projects/node_modules/@types: *new*
+  {"pollingInterval":500}
+
+FsWatches::
+/a/lib/lib.d.ts: *new*
+  {}
+/user/username/projects/myproject/b.ts: *new*
+  {}
+/user/username/projects/myproject/tsconfig.json: *new*
+  {}
+
+FsWatchesRecursive::
+/user/username/projects/myproject: *new*
+  {}
+
+Add file
+Info seq  [hh:mm:ss:mss] DirectoryWatcher:: Triggered with /user/username/projects/myproject/c.ts :: WatchInfo: /user/username/projects/myproject 1 undefined Config: /user/username/projects/myproject/tsconfig.json WatchType: Wild card directory
+Info seq  [hh:mm:ss:mss] Scheduled: /user/username/projects/myproject/tsconfig.json
+Info seq  [hh:mm:ss:mss] Scheduled: *ensureProjectForOpenFiles*
+Info seq  [hh:mm:ss:mss] Elapsed:: *ms DirectoryWatcher:: Triggered with /user/username/projects/myproject/c.ts :: WatchInfo: /user/username/projects/myproject 1 undefined Config: /user/username/projects/myproject/tsconfig.json WatchType: Wild card directory
+Before running Timeout callback:: count: 2
+1: /user/username/projects/myproject/tsconfig.json
+2: *ensureProjectForOpenFiles*
+//// [/user/username/projects/myproject/c.ts]
+export class a { prop = "hello"; foo() { return this.prop; } }
+
+
+Info seq  [hh:mm:ss:mss] Running: /user/username/projects/myproject/tsconfig.json
+Info seq  [hh:mm:ss:mss] FileWatcher:: Added:: WatchInfo: /user/username/projects/myproject/c.ts 500 undefined WatchType: Closed Script info
+Info seq  [hh:mm:ss:mss] Starting updateGraphWorker: Project: /user/username/projects/myproject/tsconfig.json
+Info seq  [hh:mm:ss:mss] Finishing updateGraphWorker: Project: /user/username/projects/myproject/tsconfig.json Version: 2 structureChanged: true structureIsReused:: Not Elapsed:: *ms
+Info seq  [hh:mm:ss:mss] Project '/user/username/projects/myproject/tsconfig.json' (Configured)
+Info seq  [hh:mm:ss:mss] 	Files (4)
+	/a/lib/lib.d.ts Text-1 "/// <reference no-default-lib=\"true\"/>\ninterface Boolean {}\ninterface Function {}\ninterface CallableFunction {}\ninterface NewableFunction {}\ninterface IArguments {}\ninterface Number { toExponential: any; }\ninterface Object {}\ninterface RegExp {}\ninterface String { charAt: any; }\ninterface Array<T> { length: number; [n: number]: T; }"
+	/user/username/projects/myproject/a.ts SVC-1-0 "export class a { prop = \"hello\"; foo() { return this.prop; } }"
+	/user/username/projects/myproject/b.ts Text-1 "export class b { prop = \"hello\"; foo() { return this.prop; } }"
+	/user/username/projects/myproject/c.ts Text-1 "export class a { prop = \"hello\"; foo() { return this.prop; } }"
+
+
+	../../../../a/lib/lib.d.ts
+	  Default library for target 'es5'
+	a.ts
+	  Matched by default include pattern '**/*'
+	b.ts
+	  Matched by default include pattern '**/*'
+	c.ts
+	  Matched by default include pattern '**/*'
+
+Info seq  [hh:mm:ss:mss] -----------------------------------------------
+Info seq  [hh:mm:ss:mss] Running: *ensureProjectForOpenFiles*
+Info seq  [hh:mm:ss:mss] Before ensureProjectForOpenFiles:
+Info seq  [hh:mm:ss:mss] Project '/user/username/projects/myproject/tsconfig.json' (Configured)
+Info seq  [hh:mm:ss:mss] 	Files (4)
+
+Info seq  [hh:mm:ss:mss] -----------------------------------------------
+Info seq  [hh:mm:ss:mss] Open files: 
+Info seq  [hh:mm:ss:mss] 	FileName: /user/username/projects/myproject/a.ts ProjectRootPath: undefined
+Info seq  [hh:mm:ss:mss] 		Projects: /user/username/projects/myproject/tsconfig.json
+Info seq  [hh:mm:ss:mss] After ensureProjectForOpenFiles:
+Info seq  [hh:mm:ss:mss] Project '/user/username/projects/myproject/tsconfig.json' (Configured)
+Info seq  [hh:mm:ss:mss] 	Files (4)
+
+Info seq  [hh:mm:ss:mss] -----------------------------------------------
+Info seq  [hh:mm:ss:mss] Open files: 
+Info seq  [hh:mm:ss:mss] 	FileName: /user/username/projects/myproject/a.ts ProjectRootPath: undefined
+Info seq  [hh:mm:ss:mss] 		Projects: /user/username/projects/myproject/tsconfig.json
+After running Timeout callback:: count: 0
+
+PolledWatches::
+/user/username/projects/myproject/node_modules/@types:
+  {"pollingInterval":500}
+/user/username/projects/node_modules/@types:
+  {"pollingInterval":500}
+
+FsWatches::
+/a/lib/lib.d.ts:
+  {}
+/user/username/projects/myproject/b.ts:
+  {}
+/user/username/projects/myproject/c.ts: *new*
+  {}
+/user/username/projects/myproject/tsconfig.json:
+  {}
+
+FsWatchesRecursive::
+/user/username/projects/myproject:
+  {}
+
+Custom watch
+Before running Timeout callback:: count: 0
+
+After running Timeout callback:: count: 0
+
+Change File
+Info seq  [hh:mm:ss:mss] FileWatcher:: Triggered with /user/username/projects/myproject/b.ts 1:: WatchInfo: /user/username/projects/myproject/b.ts 500 undefined WatchType: Closed Script info
+Info seq  [hh:mm:ss:mss] Scheduled: /user/username/projects/myproject/tsconfig.json
+Info seq  [hh:mm:ss:mss] Scheduled: *ensureProjectForOpenFiles*
+Info seq  [hh:mm:ss:mss] Elapsed:: *ms FileWatcher:: Triggered with /user/username/projects/myproject/b.ts 1:: WatchInfo: /user/username/projects/myproject/b.ts 500 undefined WatchType: Closed Script info
+Before running Timeout callback:: count: 2
+3: /user/username/projects/myproject/tsconfig.json
+4: *ensureProjectForOpenFiles*
+//// [/user/username/projects/myproject/b.ts]
+export class a { prop = "hello"; foo() { return this.prop; } }
+
+
+Info seq  [hh:mm:ss:mss] Running: /user/username/projects/myproject/tsconfig.json
+Info seq  [hh:mm:ss:mss] Starting updateGraphWorker: Project: /user/username/projects/myproject/tsconfig.json
+Info seq  [hh:mm:ss:mss] Finishing updateGraphWorker: Project: /user/username/projects/myproject/tsconfig.json Version: 3 structureChanged: false structureIsReused:: Completely Elapsed:: *ms
+Info seq  [hh:mm:ss:mss] Project '/user/username/projects/myproject/tsconfig.json' (Configured)
+Info seq  [hh:mm:ss:mss] 	Files (4)
+	/a/lib/lib.d.ts Text-1 "/// <reference no-default-lib=\"true\"/>\ninterface Boolean {}\ninterface Function {}\ninterface CallableFunction {}\ninterface NewableFunction {}\ninterface IArguments {}\ninterface Number { toExponential: any; }\ninterface Object {}\ninterface RegExp {}\ninterface String { charAt: any; }\ninterface Array<T> { length: number; [n: number]: T; }"
+	/user/username/projects/myproject/a.ts SVC-1-0 "export class a { prop = \"hello\"; foo() { return this.prop; } }"
+	/user/username/projects/myproject/b.ts Text-2 "export class a { prop = \"hello\"; foo() { return this.prop; } }"
+	/user/username/projects/myproject/c.ts Text-1 "export class a { prop = \"hello\"; foo() { return this.prop; } }"
+
+Info seq  [hh:mm:ss:mss] -----------------------------------------------
+Info seq  [hh:mm:ss:mss] Running: *ensureProjectForOpenFiles*
+Info seq  [hh:mm:ss:mss] Before ensureProjectForOpenFiles:
+Info seq  [hh:mm:ss:mss] Project '/user/username/projects/myproject/tsconfig.json' (Configured)
+Info seq  [hh:mm:ss:mss] 	Files (4)
+
+Info seq  [hh:mm:ss:mss] -----------------------------------------------
+Info seq  [hh:mm:ss:mss] Open files: 
+Info seq  [hh:mm:ss:mss] 	FileName: /user/username/projects/myproject/a.ts ProjectRootPath: undefined
+Info seq  [hh:mm:ss:mss] 		Projects: /user/username/projects/myproject/tsconfig.json
+Info seq  [hh:mm:ss:mss] After ensureProjectForOpenFiles:
+Info seq  [hh:mm:ss:mss] Project '/user/username/projects/myproject/tsconfig.json' (Configured)
+Info seq  [hh:mm:ss:mss] 	Files (4)
+
+Info seq  [hh:mm:ss:mss] -----------------------------------------------
+Info seq  [hh:mm:ss:mss] Open files: 
+Info seq  [hh:mm:ss:mss] 	FileName: /user/username/projects/myproject/a.ts ProjectRootPath: undefined
+Info seq  [hh:mm:ss:mss] 		Projects: /user/username/projects/myproject/tsconfig.json
+After running Timeout callback:: count: 0
+
+Custom watch
+Before running Timeout callback:: count: 0
+
+After running Timeout callback:: count: 0
+
+Before request
+
+Info seq  [hh:mm:ss:mss] request:
+    {
+      "command": "open",
+      "arguments": {
+        "file": "/user/username/projects/myproject/b.ts"
+      },
+      "seq": 2,
+      "type": "request"
+    }
+Info seq  [hh:mm:ss:mss] FileWatcher:: Close:: WatchInfo: /user/username/projects/myproject/b.ts 500 undefined WatchType: Closed Script info
+Info seq  [hh:mm:ss:mss] Search path: /user/username/projects/myproject
+Info seq  [hh:mm:ss:mss] For info: /user/username/projects/myproject/b.ts :: Config file name: /user/username/projects/myproject/tsconfig.json
+Info seq  [hh:mm:ss:mss] Project '/user/username/projects/myproject/tsconfig.json' (Configured)
+Info seq  [hh:mm:ss:mss] 	Files (4)
+
+Info seq  [hh:mm:ss:mss] -----------------------------------------------
+Info seq  [hh:mm:ss:mss] Open files: 
+Info seq  [hh:mm:ss:mss] 	FileName: /user/username/projects/myproject/a.ts ProjectRootPath: undefined
+Info seq  [hh:mm:ss:mss] 		Projects: /user/username/projects/myproject/tsconfig.json
+Info seq  [hh:mm:ss:mss] 	FileName: /user/username/projects/myproject/b.ts ProjectRootPath: undefined
+Info seq  [hh:mm:ss:mss] 		Projects: /user/username/projects/myproject/tsconfig.json
+Info seq  [hh:mm:ss:mss] response:
+    {
+      "responseRequired": false
+    }
+After request
+
+PolledWatches::
+/user/username/projects/myproject/node_modules/@types:
+  {"pollingInterval":500}
+/user/username/projects/node_modules/@types:
+  {"pollingInterval":500}
+
+FsWatches::
+/a/lib/lib.d.ts:
+  {}
+/user/username/projects/myproject/c.ts:
+  {}
+/user/username/projects/myproject/tsconfig.json:
+  {}
+
+FsWatches *deleted*::
+/user/username/projects/myproject/b.ts:
+  {}
+
+FsWatchesRecursive::
+/user/username/projects/myproject:
+  {}
+
+Before request
+
+Info seq  [hh:mm:ss:mss] request:
+    {
+      "command": "close",
+      "arguments": {
+        "file": "/user/username/projects/myproject/b.ts"
+      },
+      "seq": 3,
+      "type": "request"
+    }
+Info seq  [hh:mm:ss:mss] FileWatcher:: Added:: WatchInfo: /user/username/projects/myproject/b.ts 500 undefined WatchType: Closed Script info
+Info seq  [hh:mm:ss:mss] Project '/user/username/projects/myproject/tsconfig.json' (Configured)
+Info seq  [hh:mm:ss:mss] 	Files (4)
+
+Info seq  [hh:mm:ss:mss] -----------------------------------------------
+Info seq  [hh:mm:ss:mss] Open files: 
+Info seq  [hh:mm:ss:mss] 	FileName: /user/username/projects/myproject/a.ts ProjectRootPath: undefined
+Info seq  [hh:mm:ss:mss] 		Projects: /user/username/projects/myproject/tsconfig.json
+Info seq  [hh:mm:ss:mss] response:
+    {
+      "responseRequired": false
+    }
+After request
+
+PolledWatches::
+/user/username/projects/myproject/node_modules/@types:
+  {"pollingInterval":500}
+/user/username/projects/node_modules/@types:
+  {"pollingInterval":500}
+
+FsWatches::
+/a/lib/lib.d.ts:
+  {}
+/user/username/projects/myproject/b.ts: *new*
+  {}
+/user/username/projects/myproject/c.ts:
+  {}
+/user/username/projects/myproject/tsconfig.json:
+  {}
+
+FsWatchesRecursive::
+/user/username/projects/myproject:
+  {}
+
+Before request
+
+Info seq  [hh:mm:ss:mss] request:
+    {
+      "command": "watchChange",
+      "arguments": {
+        "id": 1,
+        "path": "/user/username/projects/myproject/b.ts",
+        "eventType": "update"
+      },
+      "seq": 4,
+      "type": "request"
+    }
+Info seq  [hh:mm:ss:mss] Err:: Unrecognized JSON command:
+    {"command":"watchChange","arguments":{"id":1,"path":"/user/username/projects/myproject/b.ts","eventType":"update"},"seq":4,"type":"request"}
+Info seq  [hh:mm:ss:mss] response:
+    {
+     "seq": 0,
+     "type": "response",
+     "command": "unknown",
+     "request_seq": 4,
+     "success": false,
+     "performanceData": {
+      "updateGraphDurationMs": *
+     },
+     "message": "Unrecognized JSON command: watchChange"
+    }
+Info seq  [hh:mm:ss:mss] response:
+    {
+      "responseRequired": false
+    }
+After request
diff --git a/tests/baselines/reference/tsserver/events/watchEvents/canUseWatchEvents.js b/tests/baselines/reference/tsserver/events/watchEvents/canUseWatchEvents.js
new file mode 100644
index 0000000000000..34a10b3434b73
--- /dev/null
+++ b/tests/baselines/reference/tsserver/events/watchEvents/canUseWatchEvents.js
@@ -0,0 +1,545 @@
+currentDirectory:: / useCaseSensitiveFileNames: false
+Info seq  [hh:mm:ss:mss] Provided types map file "/a/lib/typesMap.json" doesn't exist
+Before request
+//// [/user/username/projects/myproject/tsconfig.json]
+{}
+
+//// [/user/username/projects/myproject/a.ts]
+export class a { prop = "hello"; foo() { return this.prop; } }
+
+//// [/user/username/projects/myproject/b.ts]
+export class b { prop = "hello"; foo() { return this.prop; } }
+
+//// [/a/lib/lib.d.ts]
+/// <reference no-default-lib="true"/>
+interface Boolean {}
+interface Function {}
+interface CallableFunction {}
+interface NewableFunction {}
+interface IArguments {}
+interface Number { toExponential: any; }
+interface Object {}
+interface RegExp {}
+interface String { charAt: any; }
+interface Array<T> { length: number; [n: number]: T; }
+
+
+Info seq  [hh:mm:ss:mss] request:
+    {
+      "command": "open",
+      "arguments": {
+        "file": "/user/username/projects/myproject/a.ts"
+      },
+      "seq": 1,
+      "type": "request"
+    }
+Info seq  [hh:mm:ss:mss] Search path: /user/username/projects/myproject
+Info seq  [hh:mm:ss:mss] For info: /user/username/projects/myproject/a.ts :: Config file name: /user/username/projects/myproject/tsconfig.json
+Info seq  [hh:mm:ss:mss] Creating configuration project /user/username/projects/myproject/tsconfig.json
+Info seq  [hh:mm:ss:mss] FileWatcher:: Added:: WatchInfo: /user/username/projects/myproject/tsconfig.json 2000 undefined Project: /user/username/projects/myproject/tsconfig.json WatchType: Config file
+Info seq  [hh:mm:ss:mss] event:
+    {
+     "seq": 0,
+     "type": "event",
+     "event": "CustomHandler::createFileWatcher",
+     "body": {
+      "id": 1,
+      "path": "/user/username/projects/myproject/tsconfig.json"
+     }
+    }
+Custom watchFile: 1: /user/username/projects/myproject/tsconfig.json
+Info seq  [hh:mm:ss:mss] event:
+    {
+     "seq": 0,
+     "type": "event",
+     "event": "CustomHandler::projectLoadingStart",
+     "body": {
+      "project": "/user/username/projects/myproject/tsconfig.json",
+      "reason": "Creating possible configured project for /user/username/projects/myproject/a.ts to open"
+     }
+    }
+Info seq  [hh:mm:ss:mss] Config: /user/username/projects/myproject/tsconfig.json : {
+ "rootNames": [
+  "/user/username/projects/myproject/a.ts",
+  "/user/username/projects/myproject/b.ts"
+ ],
+ "options": {
+  "configFilePath": "/user/username/projects/myproject/tsconfig.json"
+ }
+}
+Info seq  [hh:mm:ss:mss] DirectoryWatcher:: Added:: WatchInfo: /user/username/projects/myproject 1 undefined Config: /user/username/projects/myproject/tsconfig.json WatchType: Wild card directory
+Info seq  [hh:mm:ss:mss] event:
+    {
+     "seq": 0,
+     "type": "event",
+     "event": "CustomHandler::createDirectoryWatcher",
+     "body": {
+      "id": 2,
+      "path": "/user/username/projects/myproject",
+      "recursive": true
+     }
+    }
+Custom watchDirectory: 2: /user/username/projects/myproject true
+Info seq  [hh:mm:ss:mss] Elapsed:: *ms DirectoryWatcher:: Added:: WatchInfo: /user/username/projects/myproject 1 undefined Config: /user/username/projects/myproject/tsconfig.json WatchType: Wild card directory
+Info seq  [hh:mm:ss:mss] FileWatcher:: Added:: WatchInfo: /user/username/projects/myproject/b.ts 500 undefined WatchType: Closed Script info
+Info seq  [hh:mm:ss:mss] event:
+    {
+     "seq": 0,
+     "type": "event",
+     "event": "CustomHandler::createFileWatcher",
+     "body": {
+      "id": 3,
+      "path": "/user/username/projects/myproject/b.ts"
+     }
+    }
+Custom watchFile: 3: /user/username/projects/myproject/b.ts
+Info seq  [hh:mm:ss:mss] Starting updateGraphWorker: Project: /user/username/projects/myproject/tsconfig.json
+Info seq  [hh:mm:ss:mss] FileWatcher:: Added:: WatchInfo: /a/lib/lib.d.ts 500 undefined WatchType: Closed Script info
+Info seq  [hh:mm:ss:mss] event:
+    {
+     "seq": 0,
+     "type": "event",
+     "event": "CustomHandler::createFileWatcher",
+     "body": {
+      "id": 4,
+      "path": "/a/lib/lib.d.ts"
+     }
+    }
+Custom watchFile: 4: /a/lib/lib.d.ts
+Info seq  [hh:mm:ss:mss] DirectoryWatcher:: Added:: WatchInfo: /user/username/projects/myproject/node_modules/@types 1 undefined Project: /user/username/projects/myproject/tsconfig.json WatchType: Type roots
+Info seq  [hh:mm:ss:mss] event:
+    {
+     "seq": 0,
+     "type": "event",
+     "event": "CustomHandler::createDirectoryWatcher",
+     "body": {
+      "id": 5,
+      "path": "/user/username/projects/myproject/node_modules/@types",
+      "recursive": true
+     }
+    }
+Custom watchDirectory: 5: /user/username/projects/myproject/node_modules/@types true
+Info seq  [hh:mm:ss:mss] Elapsed:: *ms DirectoryWatcher:: Added:: WatchInfo: /user/username/projects/myproject/node_modules/@types 1 undefined Project: /user/username/projects/myproject/tsconfig.json WatchType: Type roots
+Info seq  [hh:mm:ss:mss] DirectoryWatcher:: Added:: WatchInfo: /user/username/projects/node_modules/@types 1 undefined Project: /user/username/projects/myproject/tsconfig.json WatchType: Type roots
+Info seq  [hh:mm:ss:mss] event:
+    {
+     "seq": 0,
+     "type": "event",
+     "event": "CustomHandler::createDirectoryWatcher",
+     "body": {
+      "id": 6,
+      "path": "/user/username/projects/node_modules/@types",
+      "recursive": true
+     }
+    }
+Custom watchDirectory: 6: /user/username/projects/node_modules/@types true
+Info seq  [hh:mm:ss:mss] Elapsed:: *ms DirectoryWatcher:: Added:: WatchInfo: /user/username/projects/node_modules/@types 1 undefined Project: /user/username/projects/myproject/tsconfig.json WatchType: Type roots
+Info seq  [hh:mm:ss:mss] Finishing updateGraphWorker: Project: /user/username/projects/myproject/tsconfig.json Version: 1 structureChanged: true structureIsReused:: Not Elapsed:: *ms
+Info seq  [hh:mm:ss:mss] Project '/user/username/projects/myproject/tsconfig.json' (Configured)
+Info seq  [hh:mm:ss:mss] 	Files (3)
+	/a/lib/lib.d.ts Text-1 "/// <reference no-default-lib=\"true\"/>\ninterface Boolean {}\ninterface Function {}\ninterface CallableFunction {}\ninterface NewableFunction {}\ninterface IArguments {}\ninterface Number { toExponential: any; }\ninterface Object {}\ninterface RegExp {}\ninterface String { charAt: any; }\ninterface Array<T> { length: number; [n: number]: T; }"
+	/user/username/projects/myproject/a.ts SVC-1-0 "export class a { prop = \"hello\"; foo() { return this.prop; } }"
+	/user/username/projects/myproject/b.ts Text-1 "export class b { prop = \"hello\"; foo() { return this.prop; } }"
+
+
+	../../../../a/lib/lib.d.ts
+	  Default library for target 'es5'
+	a.ts
+	  Matched by default include pattern '**/*'
+	b.ts
+	  Matched by default include pattern '**/*'
+
+Info seq  [hh:mm:ss:mss] -----------------------------------------------
+Info seq  [hh:mm:ss:mss] event:
+    {
+     "seq": 0,
+     "type": "event",
+     "event": "CustomHandler::projectLoadingFinish",
+     "body": {
+      "project": "/user/username/projects/myproject/tsconfig.json"
+     }
+    }
+Info seq  [hh:mm:ss:mss] event:
+    {
+     "seq": 0,
+     "type": "event",
+     "event": "CustomHandler::projectInfo",
+     "body": {
+      "projectId": "4a33d78ee40d836c4f4e64c59aed976628aea0013be9585c5ff171dfc41baf98",
+      "fileStats": {
+       "js": 0,
+       "jsSize": 0,
+       "jsx": 0,
+       "jsxSize": 0,
+       "ts": 2,
+       "tsSize": 124,
+       "tsx": 0,
+       "tsxSize": 0,
+       "dts": 1,
+       "dtsSize": 334,
+       "deferred": 0,
+       "deferredSize": 0
+      },
+      "compilerOptions": {},
+      "typeAcquisition": {
+       "enable": false,
+       "include": false,
+       "exclude": false
+      },
+      "extends": false,
+      "files": false,
+      "include": false,
+      "exclude": false,
+      "compileOnSave": false,
+      "configFileName": "tsconfig.json",
+      "projectType": "configured",
+      "languageServiceEnabled": true,
+      "version": "FakeVersion"
+     }
+    }
+Info seq  [hh:mm:ss:mss] event:
+    {
+     "seq": 0,
+     "type": "event",
+     "event": "CustomHandler::configFileDiag",
+     "body": {
+      "configFileName": "/user/username/projects/myproject/tsconfig.json",
+      "diagnostics": [],
+      "triggerFile": "/user/username/projects/myproject/a.ts"
+     }
+    }
+Info seq  [hh:mm:ss:mss] Project '/user/username/projects/myproject/tsconfig.json' (Configured)
+Info seq  [hh:mm:ss:mss] 	Files (3)
+
+Info seq  [hh:mm:ss:mss] -----------------------------------------------
+Info seq  [hh:mm:ss:mss] Open files: 
+Info seq  [hh:mm:ss:mss] 	FileName: /user/username/projects/myproject/a.ts ProjectRootPath: undefined
+Info seq  [hh:mm:ss:mss] 		Projects: /user/username/projects/myproject/tsconfig.json
+Info seq  [hh:mm:ss:mss] response:
+    {
+      "responseRequired": false
+    }
+After request
+
+Custom WatchedFiles::
+/a/lib/lib.d.ts: *new*
+  {"id":4,"path":"/a/lib/lib.d.ts"}
+/user/username/projects/myproject/b.ts: *new*
+  {"id":3,"path":"/user/username/projects/myproject/b.ts"}
+/user/username/projects/myproject/tsconfig.json: *new*
+  {"id":1,"path":"/user/username/projects/myproject/tsconfig.json"}
+
+Custom WatchedDirectories:Recursive::
+/user/username/projects/myproject: *new*
+  {"id":2,"path":"/user/username/projects/myproject","recursive":true}
+/user/username/projects/myproject/node_modules/@types: *new*
+  {"id":5,"path":"/user/username/projects/myproject/node_modules/@types","recursive":true}
+/user/username/projects/node_modules/@types: *new*
+  {"id":6,"path":"/user/username/projects/node_modules/@types","recursive":true}
+
+Add file
+Before running Timeout callback:: count: 0
+//// [/user/username/projects/myproject/c.ts]
+export class a { prop = "hello"; foo() { return this.prop; } }
+
+
+After running Timeout callback:: count: 0
+
+Custom watch
+Before request
+
+Info seq  [hh:mm:ss:mss] request:
+    {
+      "command": "watchChange",
+      "arguments": {
+        "id": 2,
+        "path": "/user/username/projects/myproject/c.ts",
+        "eventType": "create"
+      },
+      "seq": 2,
+      "type": "request"
+    }
+Info seq  [hh:mm:ss:mss] DirectoryWatcher:: Triggered with /user/username/projects/myproject/c.ts :: WatchInfo: /user/username/projects/myproject 1 undefined Config: /user/username/projects/myproject/tsconfig.json WatchType: Wild card directory
+Info seq  [hh:mm:ss:mss] Scheduled: /user/username/projects/myproject/tsconfig.json
+Info seq  [hh:mm:ss:mss] Scheduled: *ensureProjectForOpenFiles*
+Info seq  [hh:mm:ss:mss] Elapsed:: *ms DirectoryWatcher:: Triggered with /user/username/projects/myproject/c.ts :: WatchInfo: /user/username/projects/myproject 1 undefined Config: /user/username/projects/myproject/tsconfig.json WatchType: Wild card directory
+Info seq  [hh:mm:ss:mss] response:
+    {
+      "responseRequired": false
+    }
+After request
+
+Before running Timeout callback:: count: 2
+1: /user/username/projects/myproject/tsconfig.json
+2: *ensureProjectForOpenFiles*
+
+Info seq  [hh:mm:ss:mss] Running: /user/username/projects/myproject/tsconfig.json
+Info seq  [hh:mm:ss:mss] FileWatcher:: Added:: WatchInfo: /user/username/projects/myproject/c.ts 500 undefined WatchType: Closed Script info
+Info seq  [hh:mm:ss:mss] event:
+    {
+     "seq": 0,
+     "type": "event",
+     "event": "CustomHandler::createFileWatcher",
+     "body": {
+      "id": 7,
+      "path": "/user/username/projects/myproject/c.ts"
+     }
+    }
+Custom watchFile: 7: /user/username/projects/myproject/c.ts
+Info seq  [hh:mm:ss:mss] Starting updateGraphWorker: Project: /user/username/projects/myproject/tsconfig.json
+Info seq  [hh:mm:ss:mss] Finishing updateGraphWorker: Project: /user/username/projects/myproject/tsconfig.json Version: 2 structureChanged: true structureIsReused:: Not Elapsed:: *ms
+Info seq  [hh:mm:ss:mss] Project '/user/username/projects/myproject/tsconfig.json' (Configured)
+Info seq  [hh:mm:ss:mss] 	Files (4)
+	/a/lib/lib.d.ts Text-1 "/// <reference no-default-lib=\"true\"/>\ninterface Boolean {}\ninterface Function {}\ninterface CallableFunction {}\ninterface NewableFunction {}\ninterface IArguments {}\ninterface Number { toExponential: any; }\ninterface Object {}\ninterface RegExp {}\ninterface String { charAt: any; }\ninterface Array<T> { length: number; [n: number]: T; }"
+	/user/username/projects/myproject/a.ts SVC-1-0 "export class a { prop = \"hello\"; foo() { return this.prop; } }"
+	/user/username/projects/myproject/b.ts Text-1 "export class b { prop = \"hello\"; foo() { return this.prop; } }"
+	/user/username/projects/myproject/c.ts Text-1 "export class a { prop = \"hello\"; foo() { return this.prop; } }"
+
+
+	../../../../a/lib/lib.d.ts
+	  Default library for target 'es5'
+	a.ts
+	  Matched by default include pattern '**/*'
+	b.ts
+	  Matched by default include pattern '**/*'
+	c.ts
+	  Matched by default include pattern '**/*'
+
+Info seq  [hh:mm:ss:mss] -----------------------------------------------
+Info seq  [hh:mm:ss:mss] Running: *ensureProjectForOpenFiles*
+Info seq  [hh:mm:ss:mss] Before ensureProjectForOpenFiles:
+Info seq  [hh:mm:ss:mss] Project '/user/username/projects/myproject/tsconfig.json' (Configured)
+Info seq  [hh:mm:ss:mss] 	Files (4)
+
+Info seq  [hh:mm:ss:mss] -----------------------------------------------
+Info seq  [hh:mm:ss:mss] Open files: 
+Info seq  [hh:mm:ss:mss] 	FileName: /user/username/projects/myproject/a.ts ProjectRootPath: undefined
+Info seq  [hh:mm:ss:mss] 		Projects: /user/username/projects/myproject/tsconfig.json
+Info seq  [hh:mm:ss:mss] After ensureProjectForOpenFiles:
+Info seq  [hh:mm:ss:mss] Project '/user/username/projects/myproject/tsconfig.json' (Configured)
+Info seq  [hh:mm:ss:mss] 	Files (4)
+
+Info seq  [hh:mm:ss:mss] -----------------------------------------------
+Info seq  [hh:mm:ss:mss] Open files: 
+Info seq  [hh:mm:ss:mss] 	FileName: /user/username/projects/myproject/a.ts ProjectRootPath: undefined
+Info seq  [hh:mm:ss:mss] 		Projects: /user/username/projects/myproject/tsconfig.json
+Info seq  [hh:mm:ss:mss] event:
+    {
+     "seq": 0,
+     "type": "event",
+     "event": "CustomHandler::projectsUpdatedInBackground",
+     "body": {
+      "openFiles": [
+       "/user/username/projects/myproject/a.ts"
+      ]
+     }
+    }
+After running Timeout callback:: count: 0
+
+Custom WatchedFiles::
+/a/lib/lib.d.ts:
+  {"id":4,"path":"/a/lib/lib.d.ts"}
+/user/username/projects/myproject/b.ts:
+  {"id":3,"path":"/user/username/projects/myproject/b.ts"}
+/user/username/projects/myproject/c.ts: *new*
+  {"id":7,"path":"/user/username/projects/myproject/c.ts"}
+/user/username/projects/myproject/tsconfig.json:
+  {"id":1,"path":"/user/username/projects/myproject/tsconfig.json"}
+
+Custom WatchedDirectories:Recursive::
+/user/username/projects/myproject:
+  {"id":2,"path":"/user/username/projects/myproject","recursive":true}
+/user/username/projects/myproject/node_modules/@types:
+  {"id":5,"path":"/user/username/projects/myproject/node_modules/@types","recursive":true}
+/user/username/projects/node_modules/@types:
+  {"id":6,"path":"/user/username/projects/node_modules/@types","recursive":true}
+
+Change File
+Before running Timeout callback:: count: 0
+//// [/user/username/projects/myproject/b.ts]
+export class a { prop = "hello"; foo() { return this.prop; } }
+
+
+After running Timeout callback:: count: 0
+
+Custom watch
+Before request
+
+Info seq  [hh:mm:ss:mss] request:
+    {
+      "command": "watchChange",
+      "arguments": {
+        "id": 3,
+        "path": "/user/username/projects/myproject/b.ts",
+        "eventType": "update"
+      },
+      "seq": 3,
+      "type": "request"
+    }
+Info seq  [hh:mm:ss:mss] FileWatcher:: Triggered with /user/username/projects/myproject/b.ts 1:: WatchInfo: /user/username/projects/myproject/b.ts 500 undefined WatchType: Closed Script info
+Info seq  [hh:mm:ss:mss] Scheduled: /user/username/projects/myproject/tsconfig.json
+Info seq  [hh:mm:ss:mss] Scheduled: *ensureProjectForOpenFiles*
+Info seq  [hh:mm:ss:mss] Elapsed:: *ms FileWatcher:: Triggered with /user/username/projects/myproject/b.ts 1:: WatchInfo: /user/username/projects/myproject/b.ts 500 undefined WatchType: Closed Script info
+Info seq  [hh:mm:ss:mss] response:
+    {
+      "responseRequired": false
+    }
+After request
+
+Before running Timeout callback:: count: 2
+3: /user/username/projects/myproject/tsconfig.json
+4: *ensureProjectForOpenFiles*
+
+Info seq  [hh:mm:ss:mss] Running: /user/username/projects/myproject/tsconfig.json
+Info seq  [hh:mm:ss:mss] Starting updateGraphWorker: Project: /user/username/projects/myproject/tsconfig.json
+Info seq  [hh:mm:ss:mss] Finishing updateGraphWorker: Project: /user/username/projects/myproject/tsconfig.json Version: 3 structureChanged: false structureIsReused:: Completely Elapsed:: *ms
+Info seq  [hh:mm:ss:mss] Project '/user/username/projects/myproject/tsconfig.json' (Configured)
+Info seq  [hh:mm:ss:mss] 	Files (4)
+	/a/lib/lib.d.ts Text-1 "/// <reference no-default-lib=\"true\"/>\ninterface Boolean {}\ninterface Function {}\ninterface CallableFunction {}\ninterface NewableFunction {}\ninterface IArguments {}\ninterface Number { toExponential: any; }\ninterface Object {}\ninterface RegExp {}\ninterface String { charAt: any; }\ninterface Array<T> { length: number; [n: number]: T; }"
+	/user/username/projects/myproject/a.ts SVC-1-0 "export class a { prop = \"hello\"; foo() { return this.prop; } }"
+	/user/username/projects/myproject/b.ts Text-2 "export class a { prop = \"hello\"; foo() { return this.prop; } }"
+	/user/username/projects/myproject/c.ts Text-1 "export class a { prop = \"hello\"; foo() { return this.prop; } }"
+
+Info seq  [hh:mm:ss:mss] -----------------------------------------------
+Info seq  [hh:mm:ss:mss] Running: *ensureProjectForOpenFiles*
+Info seq  [hh:mm:ss:mss] Before ensureProjectForOpenFiles:
+Info seq  [hh:mm:ss:mss] Project '/user/username/projects/myproject/tsconfig.json' (Configured)
+Info seq  [hh:mm:ss:mss] 	Files (4)
+
+Info seq  [hh:mm:ss:mss] -----------------------------------------------
+Info seq  [hh:mm:ss:mss] Open files: 
+Info seq  [hh:mm:ss:mss] 	FileName: /user/username/projects/myproject/a.ts ProjectRootPath: undefined
+Info seq  [hh:mm:ss:mss] 		Projects: /user/username/projects/myproject/tsconfig.json
+Info seq  [hh:mm:ss:mss] After ensureProjectForOpenFiles:
+Info seq  [hh:mm:ss:mss] Project '/user/username/projects/myproject/tsconfig.json' (Configured)
+Info seq  [hh:mm:ss:mss] 	Files (4)
+
+Info seq  [hh:mm:ss:mss] -----------------------------------------------
+Info seq  [hh:mm:ss:mss] Open files: 
+Info seq  [hh:mm:ss:mss] 	FileName: /user/username/projects/myproject/a.ts ProjectRootPath: undefined
+Info seq  [hh:mm:ss:mss] 		Projects: /user/username/projects/myproject/tsconfig.json
+Info seq  [hh:mm:ss:mss] event:
+    {
+     "seq": 0,
+     "type": "event",
+     "event": "CustomHandler::projectsUpdatedInBackground",
+     "body": {
+      "openFiles": [
+       "/user/username/projects/myproject/a.ts"
+      ]
+     }
+    }
+After running Timeout callback:: count: 0
+
+Before request
+
+Info seq  [hh:mm:ss:mss] request:
+    {
+      "command": "open",
+      "arguments": {
+        "file": "/user/username/projects/myproject/b.ts"
+      },
+      "seq": 4,
+      "type": "request"
+    }
+Info seq  [hh:mm:ss:mss] FileWatcher:: Close:: WatchInfo: /user/username/projects/myproject/b.ts 500 undefined WatchType: Closed Script info
+Info seq  [hh:mm:ss:mss] event:
+    {
+     "seq": 0,
+     "type": "event",
+     "event": "CustomHandler::closeFileWatcher",
+     "body": {
+      "id": 3
+     }
+    }
+Custom watchFile:: Close:: 3: /user/username/projects/myproject/b.ts
+Info seq  [hh:mm:ss:mss] Search path: /user/username/projects/myproject
+Info seq  [hh:mm:ss:mss] For info: /user/username/projects/myproject/b.ts :: Config file name: /user/username/projects/myproject/tsconfig.json
+Info seq  [hh:mm:ss:mss] Project '/user/username/projects/myproject/tsconfig.json' (Configured)
+Info seq  [hh:mm:ss:mss] 	Files (4)
+
+Info seq  [hh:mm:ss:mss] -----------------------------------------------
+Info seq  [hh:mm:ss:mss] Open files: 
+Info seq  [hh:mm:ss:mss] 	FileName: /user/username/projects/myproject/a.ts ProjectRootPath: undefined
+Info seq  [hh:mm:ss:mss] 		Projects: /user/username/projects/myproject/tsconfig.json
+Info seq  [hh:mm:ss:mss] 	FileName: /user/username/projects/myproject/b.ts ProjectRootPath: undefined
+Info seq  [hh:mm:ss:mss] 		Projects: /user/username/projects/myproject/tsconfig.json
+Info seq  [hh:mm:ss:mss] response:
+    {
+      "responseRequired": false
+    }
+After request
+
+Custom WatchedFiles::
+/a/lib/lib.d.ts:
+  {"id":4,"path":"/a/lib/lib.d.ts"}
+/user/username/projects/myproject/c.ts:
+  {"id":7,"path":"/user/username/projects/myproject/c.ts"}
+/user/username/projects/myproject/tsconfig.json:
+  {"id":1,"path":"/user/username/projects/myproject/tsconfig.json"}
+
+Custom WatchedFiles *deleted*::
+/user/username/projects/myproject/b.ts:
+  {"id":3,"path":"/user/username/projects/myproject/b.ts"}
+
+Custom WatchedDirectories:Recursive::
+/user/username/projects/myproject:
+  {"id":2,"path":"/user/username/projects/myproject","recursive":true}
+/user/username/projects/myproject/node_modules/@types:
+  {"id":5,"path":"/user/username/projects/myproject/node_modules/@types","recursive":true}
+/user/username/projects/node_modules/@types:
+  {"id":6,"path":"/user/username/projects/node_modules/@types","recursive":true}
+
+Before request
+
+Info seq  [hh:mm:ss:mss] request:
+    {
+      "command": "close",
+      "arguments": {
+        "file": "/user/username/projects/myproject/b.ts"
+      },
+      "seq": 5,
+      "type": "request"
+    }
+Info seq  [hh:mm:ss:mss] FileWatcher:: Added:: WatchInfo: /user/username/projects/myproject/b.ts 500 undefined WatchType: Closed Script info
+Info seq  [hh:mm:ss:mss] event:
+    {
+     "seq": 0,
+     "type": "event",
+     "event": "CustomHandler::createFileWatcher",
+     "body": {
+      "id": 8,
+      "path": "/user/username/projects/myproject/b.ts"
+     }
+    }
+Custom watchFile: 8: /user/username/projects/myproject/b.ts
+Info seq  [hh:mm:ss:mss] Project '/user/username/projects/myproject/tsconfig.json' (Configured)
+Info seq  [hh:mm:ss:mss] 	Files (4)
+
+Info seq  [hh:mm:ss:mss] -----------------------------------------------
+Info seq  [hh:mm:ss:mss] Open files: 
+Info seq  [hh:mm:ss:mss] 	FileName: /user/username/projects/myproject/a.ts ProjectRootPath: undefined
+Info seq  [hh:mm:ss:mss] 		Projects: /user/username/projects/myproject/tsconfig.json
+Info seq  [hh:mm:ss:mss] response:
+    {
+      "responseRequired": false
+    }
+After request
+
+Custom WatchedFiles::
+/a/lib/lib.d.ts:
+  {"id":4,"path":"/a/lib/lib.d.ts"}
+/user/username/projects/myproject/b.ts: *new*
+  {"id":8,"path":"/user/username/projects/myproject/b.ts"}
+/user/username/projects/myproject/c.ts:
+  {"id":7,"path":"/user/username/projects/myproject/c.ts"}
+/user/username/projects/myproject/tsconfig.json:
+  {"id":1,"path":"/user/username/projects/myproject/tsconfig.json"}
+
+Custom WatchedDirectories:Recursive::
+/user/username/projects/myproject:
+  {"id":2,"path":"/user/username/projects/myproject","recursive":true}
+/user/username/projects/myproject/node_modules/@types:
+  {"id":5,"path":"/user/username/projects/myproject/node_modules/@types","recursive":true}
+/user/username/projects/node_modules/@types:
+  {"id":6,"path":"/user/username/projects/node_modules/@types","recursive":true}