Always install the newest eligible desktop update (#2149)

* Reapply "Always revalidate desktop updates before install" This reverts commit 623c05aa4d. * fix(desktop): make update revalidation safe on quit Updater-triggered quits now bypass normal quit handling, and manifest revalidation gives up after five seconds without allowing a late install. * fix(desktop): preserve fail-closed update installs Keep cached updates deferred when quit-time validation is offline, and report validation timeouts separately from superseded releases. * fix(desktop): preserve updater quit behavior Automatic installs remain silent without relaunching, updater handoff is bounded, and background preparation failures remain visible without pinning manifest checks. * fix(desktop): keep AppImage updates manual Preserve the AppImage safety exemption by skipping ordinary quit-time installation while retaining the explicit Update now path. * fix(desktop): serialize update preparation * fix(desktop): recognize macOS updater quit handoff
2026-07-17 10:06:32 +02:00
parent a8ebd390fa
commit 70472dc945
8 changed files with 909 additions and 328 deletions
@@ -17,7 +17,19 @@ class FakeAppUpdateRuntime implements AppUpdateRuntime {
  > = [];
  private gate: ((info: RuntimeUpdateInfo) => boolean | Promise<boolean>) | null = null;
  private configuration: AppUpdateRuntimeConfiguration | null = null;
+  private downloadableUpdate: RuntimeUpdateInfo | null = null;
+  private downloadedUpdate: RuntimeUpdateInfo | null = null;
+  private activeDownload: {
+    info: RuntimeUpdateInfo;
+    promise: Promise<void>;
+    resolve(): void;
+    reject(error: Error): void;
+  } | null = null;
  checkCount = 0;
+  downloadCallCount = 0;
+  downloadedVersions: string[] = [];
+  installedVersions: string[] = [];
+  installModes: Array<{ isSilent: boolean; isForceRunAfter: boolean }> = [];

  configure(input: AppUpdateRuntimeConfiguration): void {
    this.configuration = input;
@@ -59,9 +71,42 @@ class FakeAppUpdateRuntime implements AppUpdateRuntime {
  }

  finishUpdateDownload(info: RuntimeUpdateInfo): void {
+    this.downloadedUpdate = info;
+    this.downloadedVersions.push(info.version);
    this.configuration?.onUpdateDownloaded(info);
  }

+  beginUpdateDownload(info: RuntimeUpdateInfo): {
+    resolve(): void;
+    reject(error: Error): void;
+  } {
+    this.downloadableUpdate = info;
+    this.prepareUpdate(info);
+    let resolvePromise!: () => void;
+    let rejectPromise!: (error: Error) => void;
+    const promise = new Promise<void>((resolve, reject) => {
+      resolvePromise = resolve;
+      rejectPromise = reject;
+    });
+    void promise.catch(() => undefined);
+    const activeDownload = {
+      info,
+      promise,
+      resolve: () => {
+        this.finishUpdateDownload(info);
+        this.activeDownload = null;
+        resolvePromise();
+      },
+      reject: (error: Error) => {
+        this.configuration?.onError(error);
+        this.activeDownload = null;
+        rejectPromise(error);
+      },
+    };
+    this.activeDownload = activeDownload;
+    return { resolve: activeDownload.resolve, reject: activeDownload.reject };
+  }
+
  async checkForUpdates(): Promise<{
    isUpdateAvailable: boolean;
    updateInfo: RuntimeUpdateInfo;
@@ -80,12 +125,27 @@ class FakeAppUpdateRuntime implements AppUpdateRuntime {
    }
    if (!result || !this.gate) return result;
    const admitted = await this.gate(result.updateInfo);
-    return { ...result, isUpdateAvailable: result.isUpdateAvailable && admitted };
+    const isUpdateAvailable = result.isUpdateAvailable && admitted;
+    this.downloadableUpdate = isUpdateAvailable ? result.updateInfo : null;
+    return { ...result, isUpdateAvailable };
  }

-  async downloadUpdate(): Promise<void> {}
+  async downloadUpdate(): Promise<void> {
+    this.downloadCallCount += 1;
+    if (this.activeDownload) {
+      return this.activeDownload.promise;
+    }
+    if (this.downloadableUpdate) {
+      this.finishUpdateDownload(this.downloadableUpdate);
+    }
+  }

-  quitAndInstall(): void {}
+  quitAndInstall(isSilent: boolean, isForceRunAfter: boolean): void {
+    if (this.downloadedUpdate) {
+      this.installedVersions.push(this.downloadedUpdate.version);
+      this.installModes.push({ isSilent, isForceRunAfter });
+    }
+  }
 }

 function createService(input?: { now?: () => number; bucket?: () => Promise<number> }) {
@@ -148,6 +208,33 @@ describe("app update service", () => {
    });
  });

+  it("waits for an automatic poll before starting a manual rollout-bypassing check", async () => {
+    const { runtime, service } = createService();
+    const automaticCheck = runtime.deferNextCheck();
+    const automaticPending = service.checkForAppUpdate({
+      currentVersion: "1.2.3",
+      releaseChannel: "stable",
+      intent: "automatic",
+    });
+    runtime.nextCheck({ isUpdateAvailable: true, updateInfo: rolledOutUpdate });
+    const manualPending = service.checkForAppUpdate({
+      currentVersion: "1.2.3",
+      releaseChannel: "stable",
+      intent: "manual",
+    });
+
+    await Promise.resolve();
+    expect(runtime.checkCount).toBe(1);
+
+    automaticCheck.resolve({ isUpdateAvailable: false, updateInfo: rolledOutUpdate });
+    await automaticPending;
+    const manualResult = await manualPending;
+
+    expect(runtime.checkCount).toBe(2);
+    expect(manualResult.hasUpdate).toBe(true);
+    expect(manualResult.latestVersion).toBe("1.2.4");
+  });
+
  it("performs a fresh manual check when an update is already cached", async () => {
    const { runtime, service } = createService({ bucket: async () => 0 });
    runtime.nextCheck({ isUpdateAvailable: true, updateInfo: rolledOutUpdate });
@@ -179,6 +266,218 @@ describe("app update service", () => {
    });
  });

+  it("replaces a downloaded update when a newer release is admitted", async () => {
+    const { runtime, service } = createService({ bucket: async () => 0 });
+    runtime.nextCheck({ isUpdateAvailable: true, updateInfo: rolledOutUpdate });
+
+    await service.checkForAppUpdate({
+      currentVersion: "1.2.3",
+      releaseChannel: "stable",
+      intent: "automatic",
+    });
+    runtime.finishUpdateDownload(rolledOutUpdate);
+
+    const newerUpdate = { ...rolledOutUpdate, version: "1.2.5" };
+    runtime.nextCheck({ isUpdateAvailable: true, updateInfo: newerUpdate });
+    const result = await service.checkForAppUpdate({
+      currentVersion: "1.2.3",
+      releaseChannel: "stable",
+      intent: "automatic",
+    });
+
+    expect(result).toEqual({
+      hasUpdate: true,
+      readyToInstall: false,
+      currentVersion: "1.2.3",
+      latestVersion: "1.2.5",
+      body: null,
+      date: "2026-04-28T00:00:00.000Z",
+      errorMessage: null,
+    });
+  });
+
+  it("installs the newest admitted release when quitting with an older download", async () => {
+    const { runtime, service } = createService({ bucket: async () => 0 });
+    runtime.nextCheck({ isUpdateAvailable: true, updateInfo: rolledOutUpdate });
+
+    await service.checkForAppUpdate({
+      currentVersion: "1.2.3",
+      releaseChannel: "stable",
+      intent: "automatic",
+    });
+    runtime.finishUpdateDownload(rolledOutUpdate);
+
+    const newerUpdate = { ...rolledOutUpdate, version: "1.2.5" };
+    runtime.nextCheck({ isUpdateAvailable: true, updateInfo: newerUpdate });
+    const installed = await service.installUpdateOnQuit({
+      currentVersion: "1.2.3",
+      releaseChannel: "stable",
+      signal: new AbortController().signal,
+    });
+
+    expect(installed).toBe(true);
+    expect(runtime.installedVersions).toEqual(["1.2.5"]);
+    expect(runtime.installModes).toEqual([{ isSilent: true, isForceRunAfter: false }]);
+  });
+
+  it("does not install an older download while its replacement is still rolling out", async () => {
+    const now = Date.parse("2026-04-28T12:00:00.000Z");
+    const { runtime, service } = createService({ now: () => now, bucket: async () => 0.4 });
+    const olderUpdate = {
+      ...rolledOutUpdate,
+      releaseDate: "2026-04-27T00:00:00.000Z",
+    };
+    runtime.nextCheck({ isUpdateAvailable: true, updateInfo: olderUpdate });
+
+    await service.checkForAppUpdate({
+      currentVersion: "1.2.3",
+      releaseChannel: "stable",
+      intent: "automatic",
+    });
+    runtime.finishUpdateDownload(olderUpdate);
+
+    const newerUpdate = {
+      ...rolledOutUpdate,
+      version: "1.2.5",
+      releaseDate: "2026-04-28T12:00:00.000Z",
+    };
+    runtime.nextCheck({ isUpdateAvailable: true, updateInfo: newerUpdate });
+    const installed = await service.installUpdateOnQuit({
+      currentVersion: "1.2.3",
+      releaseChannel: "stable",
+      signal: new AbortController().signal,
+    });
+
+    expect(installed).toBe(false);
+    expect(runtime.installedVersions).toEqual([]);
+  });
+
+  it("does not install after quit-time revalidation expires", async () => {
+    const { runtime, service } = createService({ bucket: async () => 0 });
+    runtime.nextCheck({ isUpdateAvailable: true, updateInfo: rolledOutUpdate });
+
+    await service.checkForAppUpdate({
+      currentVersion: "1.2.3",
+      releaseChannel: "stable",
+      intent: "automatic",
+    });
+    runtime.finishUpdateDownload(rolledOutUpdate);
+
+    const deadline = new AbortController();
+    deadline.abort();
+    runtime.nextCheck({
+      isUpdateAvailable: true,
+      updateInfo: { ...rolledOutUpdate, version: "1.2.5" },
+    });
+    const installed = await service.installUpdateOnQuit({
+      currentVersion: "1.2.3",
+      releaseChannel: "stable",
+      signal: deadline.signal,
+    });
+
+    expect(installed).toBe(false);
+    expect(runtime.installedVersions).toEqual([]);
+  });
+
+  it("does not install an unvalidated download when the quit-time check fails", async () => {
+    const { runtime, service } = createService({ bucket: async () => 0 });
+    runtime.nextCheck({ isUpdateAvailable: true, updateInfo: rolledOutUpdate });
+
+    await service.checkForAppUpdate({
+      currentVersion: "1.2.3",
+      releaseChannel: "stable",
+      intent: "automatic",
+    });
+    runtime.finishUpdateDownload(rolledOutUpdate);
+
+    runtime.failNextCheck(new Error("offline"));
+    const installed = await service.installUpdateOnQuit({
+      currentVersion: "1.2.3",
+      releaseChannel: "stable",
+      signal: new AbortController().signal,
+    });
+
+    expect(installed).toBe(false);
+    expect(runtime.installedVersions).toEqual([]);
+  });
+
+  it("rechecks for the newest release before a manual install", async () => {
+    const { runtime, service } = createService({ bucket: async () => 0.99 });
+    runtime.nextCheck({ isUpdateAvailable: true, updateInfo: rolledOutUpdate });
+
+    await service.checkForAppUpdate({
+      currentVersion: "1.2.3",
+      releaseChannel: "stable",
+      intent: "manual",
+    });
+    runtime.finishUpdateDownload(rolledOutUpdate);
+
+    const newerUpdate = { ...rolledOutUpdate, version: "1.2.5" };
+    runtime.nextCheck({ isUpdateAvailable: true, updateInfo: newerUpdate });
+    const result = await service.downloadAndInstallUpdate({
+      currentVersion: "1.2.3",
+      releaseChannel: "stable",
+    });
+
+    expect(result.installed).toBe(true);
+    expect(runtime.installedVersions).toEqual(["1.2.5"]);
+    expect(runtime.installModes).toEqual([{ isSilent: false, isForceRunAfter: true }]);
+  });
+
+  it("waits for a stale active download before downloading and installing the rechecked version", async () => {
+    const { runtime, service } = createService({ bucket: async () => 0 });
+    runtime.nextCheck({ isUpdateAvailable: true, updateInfo: rolledOutUpdate });
+    await service.checkForAppUpdate({
+      currentVersion: "1.2.3",
+      releaseChannel: "stable",
+      intent: "automatic",
+    });
+    const staleDownload = runtime.beginUpdateDownload(rolledOutUpdate);
+
+    const newerUpdate = { ...rolledOutUpdate, version: "1.2.5" };
+    runtime.nextCheck({ isUpdateAvailable: true, updateInfo: newerUpdate });
+    const installPending = service.downloadAndInstallUpdate({
+      currentVersion: "1.2.3",
+      releaseChannel: "stable",
+    });
+    await Promise.resolve();
+    expect(runtime.installedVersions).toEqual([]);
+
+    staleDownload.resolve();
+    const result = await installPending;
+
+    expect(result.installed).toBe(true);
+    expect(runtime.downloadedVersions).toEqual(["1.2.4", "1.2.5"]);
+    expect(runtime.installedVersions).toEqual(["1.2.5"]);
+  });
+
+  it("installs the rechecked version when the stale active download fails", async () => {
+    const { runtime, service } = createService({ bucket: async () => 0 });
+    runtime.nextCheck({ isUpdateAvailable: true, updateInfo: rolledOutUpdate });
+    await service.checkForAppUpdate({
+      currentVersion: "1.2.3",
+      releaseChannel: "stable",
+      intent: "automatic",
+    });
+    const staleDownload = runtime.beginUpdateDownload(rolledOutUpdate);
+
+    const newerUpdate = { ...rolledOutUpdate, version: "1.2.5" };
+    runtime.nextCheck({ isUpdateAvailable: true, updateInfo: newerUpdate });
+    const installPending = service.downloadAndInstallUpdate({
+      currentVersion: "1.2.3",
+      releaseChannel: "stable",
+    });
+    await new Promise<void>((resolve) => setImmediate(resolve));
+    expect(runtime.downloadCallCount).toBe(1);
+
+    staleDownload.reject(new Error("old download failed"));
+    const result = await installPending;
+
+    expect(result.installed).toBe(true);
+    expect(runtime.downloadedVersions).toEqual(["1.2.5"]);
+    expect(runtime.installedVersions).toEqual(["1.2.5"]);
+  });
+
  it("trusts the runtime availability decision before comparing versions", async () => {
    const { runtime, service } = createService({ bucket: async () => 0 });
    runtime.nextCheck({ isUpdateAvailable: false, updateInfo: rolledOutUpdate });
@@ -322,28 +621,26 @@ describe("app update service", () => {
    });
  });

-  it("keeps preparation errors emitted before the update check rejects", async () => {
-    const { runtime, service } = createService();
-    const deferredCheck = runtime.deferNextCheck();
-    const pending = service.checkForAppUpdate({
+  it("surfaces preparation errors without blocking newer releases", async () => {
+    const { runtime, service } = createService({ bucket: async () => 0 });
+    runtime.nextCheck({ isUpdateAvailable: true, updateInfo: rolledOutUpdate });
+
+    await service.checkForAppUpdate({
      currentVersion: "1.2.3",
      releaseChannel: "stable",
-      intent: "automatic",
+      intent: "manual",
    });
-
    runtime.prepareUpdate(rolledOutUpdate);
    runtime.failRuntime(new Error("sha512 checksum mismatch"));
-    deferredCheck.reject(new Error("sha512 checksum mismatch"));
-    const checkResult = await pending;
-    expect(checkResult.errorMessage).toBe("sha512 checksum mismatch");

-    const automaticResult = await service.checkForAppUpdate({
+    runtime.nextCheck({ isUpdateAvailable: true, updateInfo: rolledOutUpdate });
+    const failedPreparation = await service.checkForAppUpdate({
      currentVersion: "1.2.3",
      releaseChannel: "stable",
      intent: "automatic",
    });

-    expect(automaticResult).toEqual({
+    expect(failedPreparation).toEqual({
      hasUpdate: true,
      readyToInstall: false,
      currentVersion: "1.2.3",
@@ -352,19 +649,9 @@ describe("app update service", () => {
      date: "2026-04-28T00:00:00.000Z",
      errorMessage: "sha512 checksum mismatch",
    });
-  });
-
-  it("returns runtime update errors after an update fails to prepare", async () => {
-    const { runtime, service } = createService();
-    runtime.nextCheck({ isUpdateAvailable: true, updateInfo: rolledOutUpdate });
-
-    await service.checkForAppUpdate({
-      currentVersion: "1.2.3",
-      releaseChannel: "stable",
-      intent: "manual",
-    });
-    runtime.failRuntime(new Error("sha512 checksum mismatch"));

+    const newerUpdate = { ...rolledOutUpdate, version: "1.2.5" };
+    runtime.nextCheck({ isUpdateAvailable: true, updateInfo: newerUpdate });
    const result = await service.checkForAppUpdate({
      currentVersion: "1.2.3",
      releaseChannel: "stable",
@@ -375,13 +662,43 @@ describe("app update service", () => {
      hasUpdate: true,
      readyToInstall: false,
      currentVersion: "1.2.3",
-      latestVersion: "1.2.4",
+      latestVersion: "1.2.5",
      body: null,
      date: "2026-04-28T00:00:00.000Z",
-      errorMessage: "sha512 checksum mismatch",
+      errorMessage: null,
    });
  });

+  it("attributes a late preparation failure to the download that started it", async () => {
+    const { runtime, service } = createService({ bucket: async () => 0 });
+    runtime.nextCheck({ isUpdateAvailable: true, updateInfo: rolledOutUpdate });
+    await service.checkForAppUpdate({
+      currentVersion: "1.2.3",
+      releaseChannel: "stable",
+      intent: "automatic",
+    });
+    runtime.prepareUpdate(rolledOutUpdate);
+
+    const newerUpdate = { ...rolledOutUpdate, version: "1.2.5" };
+    runtime.nextCheck({ isUpdateAvailable: true, updateInfo: newerUpdate });
+    await service.checkForAppUpdate({
+      currentVersion: "1.2.3",
+      releaseChannel: "stable",
+      intent: "automatic",
+    });
+    runtime.failRuntime(new Error("old download failed"));
+
+    runtime.nextCheck({ isUpdateAvailable: true, updateInfo: newerUpdate });
+    const result = await service.checkForAppUpdate({
+      currentVersion: "1.2.3",
+      releaseChannel: "stable",
+      intent: "automatic",
+    });
+
+    expect(result.latestVersion).toBe("1.2.5");
+    expect(result.errorMessage).toBeNull();
+  });
+
  it("performs a fresh manual check after an update preparation error", async () => {
    const { runtime, service } = createService();
    runtime.nextCheck({ isUpdateAvailable: true, updateInfo: rolledOutUpdate });
@@ -391,6 +708,7 @@ describe("app update service", () => {
      releaseChannel: "stable",
      intent: "manual",
    });
+    runtime.prepareUpdate(rolledOutUpdate);
    runtime.failRuntime(new Error("sha512 checksum mismatch"));

    runtime.nextCheck({
@@ -445,91 +763,4 @@ describe("app update service", () => {
      errorMessage: null,
    });
  });
-
-  it("returns runtime update errors to multiple automatic checks before a manual retry clears them", async () => {
-    const { runtime, service } = createService();
-    runtime.nextCheck({ isUpdateAvailable: true, updateInfo: rolledOutUpdate });
-
-    await service.checkForAppUpdate({
-      currentVersion: "1.2.3",
-      releaseChannel: "stable",
-      intent: "manual",
-    });
-    runtime.failRuntime(new Error("sha512 checksum mismatch"));
-
-    const firstAutomaticResult = await service.checkForAppUpdate({
-      currentVersion: "1.2.3",
-      releaseChannel: "stable",
-      intent: "automatic",
-    });
-    const secondAutomaticResult = await service.checkForAppUpdate({
-      currentVersion: "1.2.3",
-      releaseChannel: "stable",
-      intent: "automatic",
-    });
-
-    expect(firstAutomaticResult).toEqual({
-      hasUpdate: true,
-      readyToInstall: false,
-      currentVersion: "1.2.3",
-      latestVersion: "1.2.4",
-      body: null,
-      date: "2026-04-28T00:00:00.000Z",
-      errorMessage: "sha512 checksum mismatch",
-    });
-    expect(secondAutomaticResult).toEqual(firstAutomaticResult);
-
-    runtime.nextCheck(null);
-    const retryResult = await service.checkForAppUpdate({
-      currentVersion: "1.2.3",
-      releaseChannel: "stable",
-      intent: "manual",
-    });
-
-    expect(runtime.checkCount).toBe(2);
-    expect(retryResult).toEqual({
-      hasUpdate: false,
-      readyToInstall: false,
-      currentVersion: "1.2.3",
-      latestVersion: "1.2.3",
-      body: null,
-      date: null,
-      errorMessage: null,
-    });
-  });
-
-  it("keeps runtime update errors visible after a manual retry fails", async () => {
-    const { runtime, service } = createService();
-    runtime.nextCheck({ isUpdateAvailable: true, updateInfo: rolledOutUpdate });
-
-    await service.checkForAppUpdate({
-      currentVersion: "1.2.3",
-      releaseChannel: "stable",
-      intent: "manual",
-    });
-    runtime.failRuntime(new Error("sha512 checksum mismatch"));
-
-    runtime.failNextCheck(new Error("network down"));
-    const retryResult = await service.checkForAppUpdate({
-      currentVersion: "1.2.3",
-      releaseChannel: "stable",
-      intent: "manual",
-    });
-    const automaticResult = await service.checkForAppUpdate({
-      currentVersion: "1.2.3",
-      releaseChannel: "stable",
-      intent: "automatic",
-    });
-
-    expect(retryResult.errorMessage).toBe("network down");
-    expect(automaticResult).toEqual({
-      hasUpdate: true,
-      readyToInstall: false,
-      currentVersion: "1.2.3",
-      latestVersion: "1.2.4",
-      body: null,
-      date: "2026-04-28T00:00:00.000Z",
-      errorMessage: "sha512 checksum mismatch",
-    });
-  });
 });
@@ -62,6 +62,11 @@ export interface AppUpdateService {
    },
    onBeforeQuit?: () => Promise<void>,
  ): Promise<AppUpdateInstallResult>;
+  installUpdateOnQuit(input: {
+    currentVersion: string;
+    releaseChannel: AppReleaseChannel;
+    signal: AbortSignal;
+  }): Promise<boolean>;
 }

 export interface AppUpdateServiceDeps {
@@ -96,10 +101,16 @@ function buildCheckResult(input: {

 async function performQuitAndInstall(
  runtime: AppUpdateRuntime,
-  onBeforeQuit?: () => Promise<void>,
+  {
+    onBeforeQuit,
+    restart,
+  }: {
+    onBeforeQuit?: () => Promise<void>;
+    restart: boolean;
+  },
 ): Promise<void> {
  if (onBeforeQuit) await onBeforeQuit();
-  runtime.quitAndInstall(/* isSilent */ false, /* isForceRunAfter */ true);
+  runtime.quitAndInstall(/* isSilent */ !restart, /* isForceRunAfter */ restart);
 }

 function getErrorMessage(error: unknown): string {
@@ -109,13 +120,21 @@ function getErrorMessage(error: unknown): string {
  return String(error);
 }

+function buildDeferredInstallResult(currentVersion: string): AppUpdateInstallResult {
+  return {
+    installed: false,
+    version: currentVersion,
+    message: "Update validation timed out. The update will be installed later.",
+  };
+}
+
 export function createAppUpdateService(deps: AppUpdateServiceDeps): AppUpdateService {
  let cachedUpdateInfo: RuntimeUpdateInfo | null = null;
  let downloadedUpdateVersion: string | null = null;
-  let downloading = false;
  let configuredReleaseChannel: AppReleaseChannel | null = null;
-  let runtimeErrorMessage: string | null = null;
-  let inFlightUpdateCheckCount = 0;
+  let preparationError: { version: string; message: string } | null = null;
+  let preparingUpdateVersion: string | null = null;
+  let checkQueue: Promise<void> = Promise.resolve();

  function isReadyToInstallVersion(version: string): boolean {
    return downloadedUpdateVersion === version;
@@ -124,23 +143,8 @@ export function createAppUpdateService(deps: AppUpdateServiceDeps): AppUpdateSer
  function clearUpdateState(): void {
    cachedUpdateInfo = null;
    downloadedUpdateVersion = null;
-    downloading = false;
-    runtimeErrorMessage = null;
-  }
-
-  function buildRuntimeErrorResult(currentVersion: string): AppUpdateCheckResult | null {
-    if (!runtimeErrorMessage) {
-      return null;
-    }
-
-    const info = cachedUpdateInfo;
-    return buildCheckResult({
-      currentVersion,
-      hasUpdate: info?.version !== undefined && info.version !== currentVersion,
-      readyToInstall: false,
-      info,
-      errorMessage: runtimeErrorMessage,
-    });
+    preparationError = null;
+    preparingUpdateVersion = null;
  }

  function configureRuntime(releaseChannel: AppReleaseChannel, intent: AppUpdateCheckIntent): void {
@@ -166,28 +170,47 @@ export function createAppUpdateService(deps: AppUpdateServiceDeps): AppUpdateSer
        const alreadyReady = downloadedUpdateVersion === info.version;
        cachedUpdateInfo = info;
        downloadedUpdateVersion = alreadyReady ? info.version : null;
-        downloading = !alreadyReady;
-        runtimeErrorMessage = null;
+        if (!alreadyReady && preparingUpdateVersion === null) {
+          preparingUpdateVersion = info.version;
+        }
      },
      onUpdateDownloaded(info) {
-        cachedUpdateInfo = info;
+        // A superseded download can finish after a newer manifest check. Keep
+        // the validated manifest as the install target in that case.
+        cachedUpdateInfo ??= info;
        downloadedUpdateVersion = info.version;
-        downloading = false;
-        runtimeErrorMessage = null;
+        if (preparingUpdateVersion === info.version) {
+          preparingUpdateVersion = null;
+        }
+        if (preparationError?.version === info.version) {
+          preparationError = null;
+        }
      },
      onUpdateNotAvailable() {
        clearUpdateState();
      },
      onError(error) {
-        downloading = false;
-        if (inFlightUpdateCheckCount === 0 || cachedUpdateInfo) {
-          runtimeErrorMessage = getErrorMessage(error);
+        if (preparingUpdateVersion) {
+          preparationError = {
+            version: preparingUpdateVersion,
+            message: getErrorMessage(error),
+          };
+          preparingUpdateVersion = null;
        }
        deps.reportRuntimeError?.(error);
      },
    });
  }

+  function runCheckExclusively<T>(check: () => Promise<T>): Promise<T> {
+    const result = checkQueue.then(check, check);
+    checkQueue = result.then(
+      () => undefined,
+      () => undefined,
+    );
+    return result;
+  }
+
  async function checkForAppUpdate({
    currentVersion,
    releaseChannel,
@@ -205,73 +228,56 @@ export function createAppUpdateService(deps: AppUpdateServiceDeps): AppUpdateSer
      });
    }

-    configureRuntime(releaseChannel, intent);
+    return runCheckExclusively(async () => {
+      configureRuntime(releaseChannel, intent);

-    const runtimeErrorResult = buildRuntimeErrorResult(currentVersion);
-    if (runtimeErrorResult && intent === "automatic") {
-      return runtimeErrorResult;
-    }
+      try {
+        const result = await deps.runtime.checkForUpdates();
+        if (!result || !result.updateInfo || !result.isUpdateAvailable) {
+          clearUpdateState();
+          return buildCheckResult({
+            currentVersion,
+            hasUpdate: false,
+            readyToInstall: false,
+          });
+        }

-    const cachedVersion = cachedUpdateInfo?.version ?? null;
-    if (
-      !runtimeErrorResult &&
-      intent === "automatic" &&
-      cachedVersion &&
-      cachedVersion !== currentVersion
-    ) {
-      return buildCheckResult({
-        currentVersion,
-        hasUpdate: true,
-        readyToInstall: isReadyToInstallVersion(cachedVersion),
-        info: cachedUpdateInfo,
-      });
-    }
+        const info = result.updateInfo;
+        const latestVersion = info.version;
+        const hasUpdate = latestVersion !== currentVersion;
+
+        if (hasUpdate) {
+          cachedUpdateInfo = info;
+          const errorMessage =
+            preparationError?.version === latestVersion ? preparationError.message : null;
+          if (!errorMessage) {
+            preparationError = null;
+          }
+          return buildCheckResult({
+            currentVersion,
+            hasUpdate: true,
+            readyToInstall: isReadyToInstallVersion(latestVersion),
+            info,
+            errorMessage,
+          });
+        }

-    try {
-      inFlightUpdateCheckCount += 1;
-      const result = await deps.runtime.checkForUpdates();
-      if (!result || !result.updateInfo || !result.isUpdateAvailable) {
        clearUpdateState();
        return buildCheckResult({
          currentVersion,
          hasUpdate: false,
          readyToInstall: false,
        });
-      }
-
-      const info = result.updateInfo;
-      const latestVersion = info.version;
-      const hasUpdate = latestVersion !== currentVersion;
-
-      if (hasUpdate) {
-        cachedUpdateInfo = info;
-        downloading = !isReadyToInstallVersion(latestVersion);
-        runtimeErrorMessage = null;
+      } catch (error) {
+        deps.reportCheckError?.(error);
        return buildCheckResult({
          currentVersion,
-          hasUpdate: true,
-          readyToInstall: isReadyToInstallVersion(latestVersion),
-          info,
+          hasUpdate: false,
+          readyToInstall: false,
+          errorMessage: getErrorMessage(error),
        });
      }
-
-      clearUpdateState();
-      return buildCheckResult({
-        currentVersion,
-        hasUpdate: false,
-        readyToInstall: false,
-      });
-    } catch (error) {
-      deps.reportCheckError?.(error);
-      return buildCheckResult({
-        currentVersion,
-        hasUpdate: false,
-        readyToInstall: false,
-        errorMessage: getErrorMessage(error),
-      });
-    } finally {
-      inFlightUpdateCheckCount -= 1;
-    }
+    });
  }

  async function downloadAndInstallUpdate(
@@ -292,6 +298,69 @@ export function createAppUpdateService(deps: AppUpdateServiceDeps): AppUpdateSer
      };
    }

+    const check = await checkForAppUpdate({
+      currentVersion,
+      releaseChannel,
+      intent: "manual",
+    });
+    if (!check.hasUpdate) {
+      return {
+        installed: false,
+        version: currentVersion,
+        message: check.errorMessage ?? "No update available.",
+      };
+    }
+
+    return installCachedUpdate(currentVersion, { onBeforeQuit, restart: true });
+  }
+
+  async function ensureUpdateDownloaded(
+    readyVersion: string,
+    signal?: AbortSignal,
+  ): Promise<"ready" | "aborted" | "superseded"> {
+    while (!isReadyToInstallVersion(readyVersion)) {
+      if (signal?.aborted) return "aborted";
+      if (cachedUpdateInfo?.version !== readyVersion) return "superseded";
+
+      const attemptedVersion: string = preparingUpdateVersion ?? readyVersion;
+      preparingUpdateVersion ??= readyVersion;
+      try {
+        await deps.runtime.downloadUpdate();
+      } catch (error) {
+        if (
+          attemptedVersion !== readyVersion &&
+          cachedUpdateInfo?.version === readyVersion &&
+          !signal?.aborted
+        ) {
+          continue;
+        }
+        throw error;
+      }
+
+      // electron-updater can return an older, already-running download. Its
+      // event clears that version, then the next iteration starts the newly
+      // validated release instead of treating the stale artifact as ready.
+      if (attemptedVersion === readyVersion && !isReadyToInstallVersion(readyVersion)) {
+        downloadedUpdateVersion = readyVersion;
+        preparingUpdateVersion = null;
+      }
+    }
+
+    return signal?.aborted ? "aborted" : "ready";
+  }
+
+  async function installCachedUpdate(
+    currentVersion: string,
+    {
+      onBeforeQuit,
+      signal,
+      restart,
+    }: {
+      onBeforeQuit?: () => Promise<void>;
+      signal?: AbortSignal;
+      restart: boolean;
+    },
+  ): Promise<AppUpdateInstallResult> {
    if (!cachedUpdateInfo) {
      return {
        installed: false,
@@ -300,11 +369,13 @@ export function createAppUpdateService(deps: AppUpdateServiceDeps): AppUpdateSer
      };
    }

-    configureRuntime(releaseChannel, "manual");
-
    const readyVersion = cachedUpdateInfo.version;
+    if (signal?.aborted) {
+      return buildDeferredInstallResult(currentVersion);
+    }
+
    if (isReadyToInstallVersion(readyVersion)) {
-      await performQuitAndInstall(deps.runtime, onBeforeQuit);
+      await performQuitAndInstall(deps.runtime, { onBeforeQuit, restart });
      return {
        installed: true,
        version: readyVersion,
@@ -312,21 +383,19 @@ export function createAppUpdateService(deps: AppUpdateServiceDeps): AppUpdateSer
      };
    }

-    if (downloading) {
-      return {
-        installed: false,
-        version: currentVersion,
-        message: "Update is still being prepared. Try again in a moment.",
-      };
-    }
-
-    downloading = true;
-
    try {
-      await deps.runtime.downloadUpdate();
-      downloadedUpdateVersion = readyVersion;
-      downloading = false;
-      await performQuitAndInstall(deps.runtime, onBeforeQuit);
+      const preparation = await ensureUpdateDownloaded(readyVersion, signal);
+      if (preparation === "aborted") {
+        return buildDeferredInstallResult(currentVersion);
+      }
+      if (preparation === "superseded") {
+        return {
+          installed: false,
+          version: currentVersion,
+          message: "A newer update was found and will be installed later.",
+        };
+      }
+      await performQuitAndInstall(deps.runtime, { onBeforeQuit, restart });

      return {
        installed: true,
@@ -334,7 +403,6 @@ export function createAppUpdateService(deps: AppUpdateServiceDeps): AppUpdateSer
        message: "Update downloaded. The app will restart shortly.",
      };
    } catch (error) {
-      downloading = false;
      const message = error instanceof Error ? error.message : String(error);
      deps.reportInstallError?.(message);
      return {
@@ -345,8 +413,35 @@ export function createAppUpdateService(deps: AppUpdateServiceDeps): AppUpdateSer
    }
  }

+  async function installUpdateOnQuit({
+    currentVersion,
+    releaseChannel,
+    signal,
+  }: {
+    currentVersion: string;
+    releaseChannel: AppReleaseChannel;
+    signal: AbortSignal;
+  }): Promise<boolean> {
+    if (!deps.isPackaged() || !downloadedUpdateVersion) {
+      return false;
+    }
+
+    const check = await checkForAppUpdate({
+      currentVersion,
+      releaseChannel,
+      intent: "automatic",
+    });
+    if (signal.aborted || !check.hasUpdate) {
+      return false;
+    }
+
+    const result = await installCachedUpdate(currentVersion, { signal, restart: false });
+    return result.installed;
+  }
+
  return {
    checkForAppUpdate,
    downloadAndInstallUpdate,
+    installUpdateOnQuit,
  };
 }
@@ -19,15 +19,15 @@ import {
  resolveStagingUserId,
  rolloutManifestSchema,
  shouldAdmitToRollout,
-  shouldAutoInstallOnQuit,
+  shouldInstallAppUpdateOnQuit,
 } from "./auto-updater";

-describe("shouldAutoInstallOnQuit", () => {
-  it("auto-installs on quit everywhere except Linux AppImage", () => {
-    expect(shouldAutoInstallOnQuit({ platform: "linux", isAppImage: true })).toBe(false);
-    expect(shouldAutoInstallOnQuit({ platform: "linux", isAppImage: false })).toBe(true);
-    expect(shouldAutoInstallOnQuit({ platform: "darwin", isAppImage: false })).toBe(true);
-    expect(shouldAutoInstallOnQuit({ platform: "win32", isAppImage: false })).toBe(true);
+describe("shouldInstallAppUpdateOnQuit", () => {
+  it("keeps Linux AppImage updates on the manual install path", () => {
+    expect(shouldInstallAppUpdateOnQuit({ platform: "linux", isAppImage: true })).toBe(false);
+    expect(shouldInstallAppUpdateOnQuit({ platform: "linux", isAppImage: false })).toBe(true);
+    expect(shouldInstallAppUpdateOnQuit({ platform: "darwin", isAppImage: false })).toBe(true);
+    expect(shouldInstallAppUpdateOnQuit({ platform: "win32", isAppImage: false })).toBe(true);
  });
 });

@@ -76,18 +76,12 @@ export function getStagingUserId(): Promise<string> {
  return cachedStagingUserIdPromise;
 }

-// AppImages have no install step. electron-updater "installs" by unlinking the
-// running file and mv-ing the downloaded one into place; on app quit it does this
-// via a *blocking* execFileSync(newAppImage, { APPIMAGE_EXIT_AFTER_INSTALL: "true" }).
-// That env var is only honored by AppImageLauncher, so without it the freshly
-// launched process boots the full app and never exits — the quit hangs forever,
-// with the old binary already deleted. We therefore install AppImages only on
-// explicit quitAndInstall (the "Update now" button), which takes the non-blocking
-// spawn path. Every other target keeps auto-install-on-quit, which works there.
-export function shouldAutoInstallOnQuit(input: {
+export function shouldInstallAppUpdateOnQuit(input: {
  platform: NodeJS.Platform;
  isAppImage: boolean;
 }): boolean {
+  // AppImage's no-relaunch install path blocks while launching the replacement
+  // binary, which can hang after the running file has already been replaced.
  return !(input.platform === "linux" && input.isAppImage);
 }

@@ -97,10 +91,10 @@ class ElectronAppUpdateRuntime implements AppUpdateRuntime {
  configure(input: AppUpdateRuntimeConfiguration): void {
    autoUpdater.autoDownload = true;
    autoUpdater.autoRunAppAfterInstall = true;
-    autoUpdater.autoInstallOnAppQuit = shouldAutoInstallOnQuit({
-      platform: process.platform,
-      isAppImage: Boolean(process.env.APPIMAGE),
-    });
+    // Paseo revalidates the current manifest before explicitly installing on quit.
+    // Electron's built-in handler would install an older download without checking
+    // whether a newer release has superseded it.
+    autoUpdater.autoInstallOnAppQuit = false;
    autoUpdater.allowPrerelease = input.releaseChannel === "beta";
    autoUpdater.channel = input.releaseChannel === "beta" ? "beta" : "latest";
    autoUpdater.allowDowngrade = false;
@@ -143,6 +137,7 @@ class ElectronAppUpdateRuntime implements AppUpdateRuntime {
  }

  quitAndInstall(isSilent: boolean, isForceRunAfter: boolean): void {
+    autoUpdater.autoRunAppAfterInstall = isForceRunAfter;
    autoUpdater.quitAndInstall(isSilent, isForceRunAfter);
  }
 }
@@ -194,3 +189,24 @@ export async function downloadAndInstallUpdate(
    onBeforeQuit,
  );
 }
+
+export async function installAppUpdateOnQuit({
+  currentVersion,
+  releaseChannel,
+  signal,
+}: {
+  currentVersion: string;
+  releaseChannel: AppReleaseChannel;
+  signal: AbortSignal;
+}): Promise<boolean> {
+  if (
+    !shouldInstallAppUpdateOnQuit({
+      platform: process.platform,
+      isAppImage: Boolean(process.env.APPIMAGE),
+    })
+  ) {
+    return false;
+  }
+
+  return appUpdateService.installUpdateOnQuit({ currentVersion, releaseChannel, signal });
+}