notebook file watch re #104209.

src/vs/workbench/contrib/notebook/browser/notebookEditorInput.ts

@@ -14,6 +14,7 @@ import { INotebookEditorModelResolverService } from 'vs/workbench/contrib/notebo
 import { IReference } from 'vs/base/common/lifecycle';
 import { INotebookEditorModel } from 'vs/workbench/contrib/notebook/common/notebookCommon';
 import { IPathService } from 'vs/workbench/services/path/common/pathService';
+import { IFileService } from 'vs/platform/files/common/files';
 
 interface NotebookEditorInputOptions {
 	startDirty?: boolean;
@@ -39,10 +40,33 @@ export class NotebookEditorInput extends EditorInput {
 		@IFilesConfigurationService private readonly _filesConfigurationService: IFilesConfigurationService,
 		@IFileDialogService private readonly _fileDialogService: IFileDialogService,
 		@IPathService private readonly _pathService: IPathService,
-		@IInstantiationService private readonly _instantiationService: IInstantiationService
+		@IInstantiationService private readonly _instantiationService: IInstantiationService,
+		@IFileService private readonly fileService: IFileService,
 	) {
 		super();
 		this._defaultDirtyState = !!options.startDirty;
+
+		this._register(this.fileService.watch(this.resource));
+		this.setupListeners();
+	}
+
+	async setupListeners() {
+		this._register(this.fileService.onDidFilesChange(async e => {
+			if (this._textModel && !this.isDirty() && e.contains(this.resource)) {
+				const lastResolvedFileStat = this._textModel.object.lastResolvedFileStat;
+
+				if (!lastResolvedFileStat) {
+					return;
+				}
+
+				const newStats = await this.fileService.resolve(this.resource, { resolveMetadata: true });
+
+				if (lastResolvedFileStat && newStats && newStats.mtime > lastResolvedFileStat.mtime) {
+					console.log(newStats);
+					await this._textModel.object.revert();
+				}
+			}
+		}));
 	}
 
 	getTypeId(): string {

src/vs/workbench/contrib/notebook/common/notebookCommon.ts

@@ -18,6 +18,7 @@ import { CancellationToken } from 'vs/base/common/cancellation';
 import { Schemas } from 'vs/base/common/network';
 import { IRevertOptions } from 'vs/workbench/common/editor';
 import { basename } from 'vs/base/common/path';
+import { IFileStatWithMetadata } from 'vs/platform/files/common/files';
 
 export enum CellKind {
 	Markdown = 1,
@@ -595,6 +596,7 @@ export interface INotebookEditorModel extends IEditorModel {
 	readonly resource: URI;
 	readonly viewType: string;
 	readonly notebook: NotebookTextModel;
+	readonly lastResolvedFileStat: IFileStatWithMetadata | undefined;
 	isDirty(): boolean;
 	isUntitled(): boolean;
 	save(): Promise<boolean>;

src/vs/workbench/contrib/notebook/common/notebookEditorModel.ts

@@ -44,6 +44,10 @@ export class NotebookEditorModel extends EditorModel implements IWorkingCopy, IN
 	private _notebook!: NotebookTextModel;
 	private _lastResolvedFileStat: IFileStatWithMetadata | undefined;
 
+	get lastResolvedFileStat() {
+		return this._lastResolvedFileStat;
+	}
+
 	get notebook() {
 		return this._notebook;
 	}