Add a notification that lets you know when an update is out

The easiest way to test this is probably to change the version in your
package.json and delete the last notification storage item.

1. change version in root `package.json`
2. Open DevTools > Application > Storage (top-level)
3. Click "Clear site data"
4. See update notification

Index: code-server/lib/vscode/src/vs/workbench/browser/client.ts
===================================================================
--- code-server.orig/lib/vscode/src/vs/workbench/browser/client.ts
+++ code-server/lib/vscode/src/vs/workbench/browser/client.ts
@@ -1,10 +1,16 @@
 import { Disposable } from "../../base/common/lifecycle.js";
 import { localize } from '../../nls.js';
+import { ILogService } from '../../platform/log/common/log.js';
 import { INotificationService, Severity } from '../../platform/notification/common/notification.js';
+import { IProductService } from '../../platform/product/common/productService.js';
+import { IStorageService, StorageScope, StorageTarget } from '../../platform/storage/common/storage.js';
 
 export class CodeServerClient extends Disposable {
 	constructor (
+		@ILogService private logService: ILogService,
 		@INotificationService private notificationService: INotificationService,
+		@IProductService private productService: IProductService,
+		@IStorageService private storageService: IStorageService,
 	) {
 		super();
 	}
@@ -71,5 +77,59 @@ export class CodeServerClient extends Di
 				},
 			});
 		}
+
+		if (this.productService.updateEndpoint) {
+			this.checkUpdates(this.productService.updateEndpoint)
+		}
+	}
+
+	private checkUpdates(updateEndpoint: string) {
+		const getUpdate = async (updateCheckEndpoint: string): Promise<void> => {
+			this.logService.debug('Checking for update...');
+
+			const response = await fetch(updateCheckEndpoint, {
+				headers: { Accept: 'application/json' },
+			});
+			if (!response.ok) {
+				throw new Error(response.statusText);
+			}
+			const json = await response.json();
+			if (json.error) {
+				throw new Error(json.error);
+			}
+			if (json.isLatest) {
+				return;
+			}
+
+			const lastNoti = this.storageService.getNumber('csLastUpdateNotification', StorageScope.APPLICATION);
+			if (lastNoti) {
+				// Only remind them again after 1 week.
+				const timeout = 1000 * 60 * 60 * 24 * 7;
+				const threshold = lastNoti + timeout;
+				if (Date.now() < threshold) {
+					return;
+				}
+			}
+
+			this.storageService.store('csLastUpdateNotification', Date.now(), StorageScope.APPLICATION, StorageTarget.MACHINE);
+
+			this.notificationService.notify({
+				severity: Severity.Info,
+				message: `[code-server v${json.latest}](https://github.com/cdr/code-server/releases/tag/v${json.latest}) has been released!`,
+			});
+		};
+
+		const updateLoop = (): void => {
+			getUpdate(updateEndpoint)
+				.catch(error => {
+					this.logService.debug(`failed to check for update: ${error}`);
+				})
+				.finally(() => {
+					// Check again every 6 hours.
+					setTimeout(updateLoop, 1000 * 60 * 60 * 6);
+				});
+		};
+
+		updateLoop();
 	}
 }
Index: code-server/lib/vscode/src/vs/base/common/product.ts
===================================================================
--- code-server.orig/lib/vscode/src/vs/base/common/product.ts
+++ code-server/lib/vscode/src/vs/base/common/product.ts
@@ -57,6 +57,7 @@ export type ExtensionVirtualWorkspaceSup
 export interface IProductConfiguration {
 	readonly codeServerVersion?: string
 	readonly rootEndpoint?: string
+	readonly updateEndpoint?: string
 
 	readonly version: string;
 	readonly date?: string;
Index: code-server/lib/vscode/src/vs/server/node/webClientServer.ts
===================================================================
--- code-server.orig/lib/vscode/src/vs/server/node/webClientServer.ts
+++ code-server/lib/vscode/src/vs/server/node/webClientServer.ts
@@ -312,6 +312,7 @@ export class WebClientServer {
 		const productConfiguration = {
 			codeServerVersion: this._productService.codeServerVersion,
 			rootEndpoint: base,
+			updateEndpoint: !this._environmentService.args['disable-update-check'] ? base + '/update/check' : undefined,
 			embedderIdentifier: 'server-distro',
 			extensionsGallery: this._productService.extensionsGallery,
 		} satisfies Partial<IProductConfiguration>;
Index: code-server/lib/vscode/src/vs/server/node/serverEnvironmentService.ts
===================================================================
--- code-server.orig/lib/vscode/src/vs/server/node/serverEnvironmentService.ts
+++ code-server/lib/vscode/src/vs/server/node/serverEnvironmentService.ts
@@ -13,6 +13,8 @@ import { memoize } from '../../base/comm
 import { URI } from '../../base/common/uri.js';
 
 export const serverOptions: OptionDescriptions<Required<ServerParsedArgs>> = {
+	/* ----- code-server ----- */
+	'disable-update-check': { type: 'boolean' },
 
 	/* ----- server setup ----- */
 
@@ -93,6 +95,8 @@ export const serverOptions: OptionDescri
 };
 
 export interface ServerParsedArgs {
+	/* ----- code-server ----- */
+	'disable-update-check'?: boolean;
 
 	/* ----- server setup ----- */