Merge pull request 'Desktop: mirror the login tokens into the OS keychain (#105, step 1)' (#254) from desktop-keychain-mirror into lotus

Merge pull request #254: desktop keychain mirror (#105, step 1)

e2e/local-homeserver.spec.ts

@@ -257,12 +257,21 @@ test.describe('local homeserver regression', () => {
     await page.clock.install({ time: Date.now() + 14 * 60 * 1000 });
     await loginUI(page, alice);
     await openRoom(page, room);
-    for (let i = 0; i < 4; i += 1) {
-      // eslint-disable-next-line no-await-in-loop
-      await sendText(bob, room, `tick ${i}`);
-      // eslint-disable-next-line no-await-in-loop
-      await page.waitForTimeout(500);
-    }
+    const ticks = async (from: number, n: number) => {
+      for (let i = from; i < from + n; i += 1) {
+        // eslint-disable-next-line no-await-in-loop
+        await sendText(bob, room, `tick ${i}`);
+        // eslint-disable-next-line no-await-in-loop
+        await page.waitForTimeout(500);
+      }
+    };
+    await ticks(0, 4);
+    // "Ahead" could be a late delivery (a stalled server), so it is only
+    // reported once it has held for a minute of fresh samples.
+    await page.waitForTimeout(2000);
+    await expect(page.getByText(/clock is .*ahead of the server/)).toHaveCount(0);
+    await page.clock.fastForward('01:05');
+    await ticks(4, 2);
     await expect(page.getByText(/clock is .*14 minutes ahead of the server/)).toBeVisible();
     await page.getByRole('button', { name: 'Dismiss for 24 h' }).click();
     await expect(page.getByText(/clock is .*ahead of the server/)).toHaveCount(0);

src/app/features/call-status/CallStatus.tsx

@@ -72,9 +72,9 @@ export function CallStatus({ callEmbed }: CallStatusProps) {
                     size="T200"
                     truncate
                     style={{ color: color.Warning.Main }}
-                    title="Fix your computer's clock — calls and encryption depend on it"
+                    title="This device's clock is off. Calls and encryption depend on it: turn on automatic time in your system settings."
                   >
-                    Clock {describeSkewVsServer(clockSkew.skewMs)} — calls will fail
+                    Device clock {describeSkewVsServer(clockSkew.skewMs)}: calls may fail
                   </Text>
                 </>
               )}

src/app/features/settings/general/General.tsx

@@ -114,6 +114,7 @@ import { SequenceCardStyle } from '../styles.css';
 import { UpdateProgress, useTauriUpdater } from '../../../hooks/useTauriUpdater';
 import { describeUpdateError, manualDownloadUrl } from '../../../utils/updateErrors';
 import { isTauri as isTauriEnv, invokeTauri, tauriInvoke } from '../../../hooks/useTauri';
+import { useKeychainMirrorStatus } from '../../../state/keychainMirror';
 import { isSafeGlobalToggleKey } from '../../../hooks/useCallHotkeys';
 import { customWindowChromeAtom } from '../../../state/customWindowChrome';
 import { useDateFormatItems } from '../../../hooks/useDateFormat';
@@ -238,6 +239,27 @@ function AutostartSetting() {
   );
 }
 
+// [Gitea #105] Desktop: whether the login is also kept in the OS keychain.
+function KeychainMirrorSetting() {
+  const status = useKeychainMirrorStatus();
+  if (!isTauriEnv() || status.state === 'idle' || status.state === 'cleared') return null;
+  let description: string;
+  if (status.state === 'ok') {
+    description =
+      "A copy of your login is kept in the system keychain (Windows Credential Manager). A later update will keep it only there, out of the app's data folder.";
+  } else if (status.state === 'unsupported') {
+    description =
+      "Not available on this system yet. Your login is saved in the app's data folder, as before.";
+  } else {
+    description = `Couldn't save a copy to the system keychain (${status.error}). You stay logged in; your login is saved in the app's data folder, as before.`;
+  }
+  return (
+    <SequenceCard className={SequenceCardStyle} variant="SurfaceVariant" direction="Column">
+      <SettingTile title="Login in the system keychain" description={description} />
+    </SequenceCard>
+  );
+}
+
 type ThemeSelectorProps = {
   themeNames: Record<string, string>;
   themes: Theme[];
@@ -570,6 +592,7 @@ function Appearance() {
 
       <DesktopChromeSetting />
       <AutostartSetting />
+      <KeychainMirrorSetting />
 
       <SequenceCard className={SequenceCardStyle} variant="SurfaceVariant" direction="Column">
         <SettingTile

src/app/hooks/useClientConfig.ts

@@ -26,6 +26,15 @@ export type ClientConfig = {
    */
   elementCallUrl?: string;
 
+  /**
+   * [Gitea #43] Desktop only: the loopback origin the desktop app's local
+   * server also answers on (e.g. "http://127.0.0.1:44548"), to load the
+   * bundled call page from a different origin than the app
+   * ("http://localhost:44548"). Set by cinny-desktop together with the server
+   * and CSP changes it needs; unset keeps the same-origin call page.
+   */
+  desktopCallOrigin?: string;
+
   /**
    * Absolute https URL of the public web app (e.g. https://chat.lotusguild.org).
    * The desktop app sets it so it can hand calls it can't make to the browser.

src/app/pages/App.tsx

@@ -36,7 +36,11 @@ import { applyCustomAccent, removeCustomAccent } from '../utils/accentColor';
 import { zIndices } from '../styles/zIndex';
 import { OIDC_CALLBACK_PATH } from './paths';
 import { OidcCallback } from './auth/oidc/OidcCallback';
-import { resolveCallPageUrl, setCallPageUrl } from '../plugins/call/callPageUrl';
+import {
+  resolveCallPageUrl,
+  resolveDesktopCallPageUrl,
+  setCallPageUrl,
+} from '../plugins/call/callPageUrl';
 
 // The emoji families (Twemoji when "Twitter emoji" is on, Twemoji flags on
 // Windows — see SystemEmojiFeature) must sit before the generic family, or the
@@ -223,7 +227,15 @@ function App() {
                 >
                   {(clientConfig) => {
                     // [Gitea #43] Idempotent: where the call page is loaded from.
-                    setCallPageUrl(resolveCallPageUrl(clientConfig.elementCallUrl, isTauri()));
+                    setCallPageUrl(
+                      isTauri()
+                        ? resolveDesktopCallPageUrl(
+                            clientConfig.desktopCallOrigin,
+                            window.location.origin,
+                            import.meta.env.BASE_URL,
+                          )
+                        : resolveCallPageUrl(clientConfig.elementCallUrl, false),
+                    );
                     return (
                       <ClientConfigProvider value={clientConfig}>
                         <QueryClientProvider client={queryClient}>

src/app/pages/client/ClientNonUIFeatures.tsx

@@ -1072,6 +1072,10 @@ function ClockSkewFeature() {
       data,
     ) => {
       if (!data.liveEvent) return;
+      // Only events our homeserver stamped: a federated event's
+      // origin_server_ts is the other server's clock.
+      const senderServer = mEvent.getSender()?.split(':').slice(1).join(':');
+      if (senderServer !== mx.getDomain()) return;
       monitor.sample(mEvent.getTs(), mEvent.getAge(), mEvent.localTimestamp);
     };
     mx.on(RoomEvent.Timeline, onTimeline);

src/app/pages/client/ClockSkewBanner.tsx

@@ -19,7 +19,7 @@ const readDismissedUntil = (): number => {
 };
 
 /**
- * [Gitea #158] "Your computer's clock is 14 minutes ahead of the server."
+ * [Gitea #158] "This device's clock is 14 minutes ahead of the server."
  * Same slot and style as the sync banners. Shown while the skew monitor is
  * over its threshold; the direction matters, so it is said. Dismissable for
  * 24 h; never auto-corrects anything.
@@ -53,8 +53,8 @@ export function ClockSkewBanner() {
       >
         <Box alignItems="Center" gap="300" wrap="Wrap" justifyContent="Center">
           <Text size="L400" align="Center">
-            Your computer&apos;s clock is <b>{describeSkewVsServer(skewMs)}</b>. Encrypted messages
-            and voice calls will fail until it is fixed.
+            This device&apos;s clock is <b>{describeSkewVsServer(skewMs)}</b>. Voice calls and
+            encrypted messages can fail until it&apos;s corrected.
           </Text>
           <Button
             size="300"

src/app/plugins/call/callPageUrl.test.ts

@@ -1,6 +1,6 @@
 import { test } from 'node:test';
 import assert from 'node:assert/strict';
-import { resolveCallPageUrl } from './callPageUrl';
+import { resolveCallPageUrl, resolveDesktopCallPageUrl } from './callPageUrl';
 
 const URL_OK = 'https://call.chat.example.org/public/element-call/index.html';
 
@@ -38,3 +38,44 @@ test('anything else falls back to the bundled page', () => {
     'data:text/html,x',
   ].forEach((v) => assert.equal(resolveCallPageUrl(v, false), undefined, String(v)));
 });
+
+const APP = 'http://localhost:44548';
+const PAGE = '/public/element-call/index.html';
+
+test('desktop: the bundled page from the loopback origin on the same port', () => {
+  assert.equal(
+    resolveDesktopCallPageUrl('http://127.0.0.1:44548', APP, '/'),
+    `http://127.0.0.1:44548${PAGE}`,
+  );
+  assert.equal(
+    resolveDesktopCallPageUrl('http://127.0.0.1:44548/', APP, '/app/'),
+    `http://127.0.0.1:44548/app${PAGE}`,
+  );
+});
+
+test('desktop: unset or anything but same-port loopback http keeps the same-origin page', () => {
+  [
+    undefined,
+    '',
+    'http://127.0.0.1:44549',
+    'http://127.0.0.1',
+    'https://127.0.0.1:44548',
+    'http://localhost:44548',
+    'http://[::1]:44548',
+    'http://10.0.0.5:44548',
+    'https://call.chat.lotusguild.org',
+    'http://127.0.0.1:44548/evil/',
+    'http://127.0.0.1:44548/?x=1',
+    'http://user:pw@127.0.0.1:44548',
+    'not a url',
+    42,
+  ].forEach((v) => assert.equal(resolveDesktopCallPageUrl(v, APP, '/'), undefined, String(v)));
+});
+
+test('desktop: only when the app itself runs on http://localhost (release builds)', () => {
+  const v = 'http://127.0.0.1:44548';
+  assert.equal(resolveDesktopCallPageUrl(v, 'tauri://localhost', '/'), undefined);
+  assert.equal(resolveDesktopCallPageUrl(v, 'http://tauri.localhost', '/'), undefined);
+  assert.equal(resolveDesktopCallPageUrl(v, 'https://chat.lotusguild.org', '/'), undefined);
+  assert.equal(resolveDesktopCallPageUrl(v, 'http://localhost', '/'), undefined);
+});

src/app/plugins/call/callPageUrl.ts

@@ -7,9 +7,9 @@
  * app loads it from that origin instead, so the call frame can no longer
  * reach this origin's storage (login token, crypto store) or service worker.
  *
- * Web only: the desktop app keeps its bundled copy (its CSP doesn't allow
- * another frame origin, and a network copy could drift from the bundle).
- * Anything that isn't an absolute https URL (http only on localhost, for
+ * Web only: the desktop app keeps its bundled copy (a network copy could
+ * drift from the bundle); see resolveDesktopCallPageUrl for how it isolates
+ * it. Anything that isn't an absolute https URL (http only on localhost, for
  * development) is ignored, so a bad value falls
  * back to the bundled page instead of breaking calls.
  */
@@ -28,6 +28,40 @@ export const resolveCallPageUrl = (value: unknown, desktop: boolean): string | u
   }
 };
 
+/**
+ * [Gitea #43] Desktop: the bundled call page from a second origin.
+ *
+ * The desktop app is served by its local server at http://localhost:<port>.
+ * The same server answers on http://127.0.0.1:<port>, which is a different
+ * origin (and still a secure context), so loading the bundled call page from
+ * there cuts the call frame off from the app's storage (login token, crypto
+ * store) without a network copy that could drift from the bundle.
+ *
+ * Only used when cinny-desktop sets `desktopCallOrigin` (it ships the server
+ * and CSP changes this needs in the same release), only for a loopback http
+ * origin on the SAME port as the app, and only when the app itself runs on
+ * http://localhost (release builds). Anything else keeps the same-origin page.
+ */
+export const resolveDesktopCallPageUrl = (
+  value: unknown,
+  appOrigin: string,
+  basePath: string,
+): string | undefined => {
+  if (typeof value !== 'string' || value.trim() === '') return undefined;
+  try {
+    const app = new URL(appOrigin);
+    const call = new URL(value);
+    if (app.protocol !== 'http:' || app.hostname !== 'localhost' || !app.port) return undefined;
+    if (call.protocol !== 'http:' || call.hostname !== '127.0.0.1') return undefined;
+    if (call.port !== app.port || call.username || call.password) return undefined;
+    if (call.pathname !== '/' || call.search || call.hash) return undefined;
+    const base = basePath.replace(/\/+$/, '');
+    return `${call.origin}${base}/public/element-call/index.html`;
+  } catch {
+    return undefined;
+  }
+};
+
 let callPageUrl: string | undefined;
 
 export const setCallPageUrl = (url: string | undefined): void => {

src/app/state/keychainMirror.test.ts

@@ -0,0 +1,117 @@
+import { test } from 'node:test';
+import assert from 'node:assert/strict';
+import { KeychainInvoke, sameTokens, syncKeychain, tokensOf } from './keychainMirror';
+import type { Session } from './sessions';
+
+const session: Session = {
+  baseUrl: 'https://matrix.example.org',
+  userId: '@alice:example.org',
+  deviceId: 'DEV1',
+  accessToken: 'syt_token',
+  refreshToken: 'mar_refresh',
+};
+
+/** An in-memory keychain behind the same commands the desktop app exposes. */
+const fakeKeychain = (opts: { supported?: boolean; failSet?: boolean; corrupt?: boolean } = {}) => {
+  let stored: unknown = null;
+  const calls: string[] = [];
+  const invoke: KeychainInvoke = async (cmd, args) => {
+    calls.push(cmd);
+    switch (cmd) {
+      case 'secure_session_supported':
+        return opts.supported ?? true;
+      case 'secure_session_get':
+        return stored;
+      case 'secure_session_set':
+        if (opts.failSet) throw new Error('Access is denied.');
+        stored = opts.corrupt ? { ...(args?.tokens as object), accessToken: 'x' } : args?.tokens;
+        return null;
+      case 'secure_session_clear':
+        stored = null;
+        return null;
+      default:
+        throw new Error(`unknown ${cmd}`);
+    }
+  };
+  return { invoke, calls, get: () => stored };
+};
+
+test('stores the tokens (not the whole session) and verifies them', async () => {
+  const kc = fakeKeychain();
+  assert.deepEqual(await syncKeychain(kc.invoke, session), { state: 'ok' });
+  assert.deepEqual(kc.get(), {
+    userId: '@alice:example.org',
+    deviceId: 'DEV1',
+    accessToken: 'syt_token',
+    refreshToken: 'mar_refresh',
+  });
+  assert.deepEqual(kc.calls, [
+    'secure_session_supported',
+    'secure_session_get',
+    'secure_session_set',
+    'secure_session_get',
+  ]);
+});
+
+test('an up-to-date copy is not rewritten', async () => {
+  const kc = fakeKeychain();
+  await syncKeychain(kc.invoke, session);
+  kc.calls.length = 0;
+  assert.deepEqual(await syncKeychain(kc.invoke, session), { state: 'ok' });
+  assert.deepEqual(kc.calls, ['secure_session_supported', 'secure_session_get']);
+});
+
+test('a token rotation rewrites; no session clears', async () => {
+  const kc = fakeKeychain();
+  await syncKeychain(kc.invoke, session);
+  await syncKeychain(kc.invoke, { ...session, accessToken: 'syt_new', refreshToken: undefined });
+  assert.equal((kc.get() as { accessToken: string }).accessToken, 'syt_new');
+  assert.equal('refreshToken' in (kc.get() as object), false);
+  assert.deepEqual(await syncKeychain(kc.invoke, null), { state: 'cleared' });
+  assert.equal(kc.get(), null);
+});
+
+test('unsupported platform: nothing is touched', async () => {
+  const kc = fakeKeychain({ supported: false });
+  assert.deepEqual(await syncKeychain(kc.invoke, session), { state: 'unsupported' });
+  assert.deepEqual(kc.calls, ['secure_session_supported']);
+});
+
+test('failures become a status, never an exception', async () => {
+  assert.deepEqual(await syncKeychain(fakeKeychain({ failSet: true }).invoke, session), {
+    state: 'error',
+    error: 'Access is denied.',
+  });
+  assert.deepEqual(await syncKeychain(fakeKeychain({ corrupt: true }).invoke, session), {
+    state: 'error',
+    error: 'read-back did not match',
+  });
+  // The credential store hangs (the support check itself is instant).
+  const hung: KeychainInvoke = async (cmd) =>
+    cmd === 'secure_session_supported'
+      ? true
+      : new Promise(() => {
+          /* never settles */
+        });
+  assert.deepEqual(await syncKeychain(hung, session, 50), {
+    state: 'error',
+    error: 'keychain timed out',
+  });
+});
+
+test('a desktop build without the commands reads as unsupported, not an error', async () => {
+  const missingCommand: KeychainInvoke = async (cmd) => {
+    throw new Error(`Command ${cmd} not found`);
+  };
+  assert.deepEqual(await syncKeychain(missingCommand, session), { state: 'unsupported' });
+});
+
+test('sameTokens compares only the secrets, treating a missing refresh token as absent', () => {
+  const t = tokensOf({ ...session, refreshToken: undefined });
+  assert.equal(sameTokens({ ...t }, t), true);
+  assert.equal(sameTokens({ ...t, refreshToken: undefined }, t), true);
+  assert.equal(sameTokens({ ...t, accessToken: 'other' }, t), false);
+  assert.equal(sameTokens({ ...t, refreshToken: 'r' }, t), false);
+  assert.equal(sameTokens(null, t), false);
+  assert.equal(sameTokens('string', t), false);
+});

src/app/state/keychainMirror.ts

@@ -0,0 +1,141 @@
+import { useEffect, useState } from 'react';
+import { getFallbackSession, onSessionPersisted, Session } from './sessions';
+
+/**
+ * [Gitea #105] Desktop, step 1: mirror the login tokens into the OS keychain.
+ *
+ * The session is still read from localStorage exactly as before; this only
+ * keeps a copy in the keychain (Windows Credential Manager) and checks it by
+ * reading it back, so real installs prove the keychain works before step 2
+ * switches reads over to it. Nothing here can log anyone out: every failure
+ * just records a status for Settings.
+ *
+ * Writes are serialized (a token rotation right after login must not race
+ * the login's write) and time out, so a hung credential store can't pile up.
+ * When there's no session the keychain entry is cleared, which also covers a
+ * logout whose page reload beat the clear.
+ */
+
+export type KeychainTokens = {
+  userId: string;
+  deviceId: string;
+  accessToken: string;
+  refreshToken?: string;
+};
+
+export type KeychainMirrorStatus =
+  | { state: 'idle' }
+  | { state: 'unsupported' }
+  | { state: 'ok' }
+  | { state: 'cleared' }
+  | { state: 'error'; error: string };
+
+export type KeychainInvoke = (cmd: string, args?: Record<string, unknown>) => Promise<unknown>;
+
+export const KEYCHAIN_TIMEOUT_MS = 5000;
+
+export const tokensOf = (session: Session): KeychainTokens => ({
+  userId: session.userId,
+  deviceId: session.deviceId,
+  accessToken: session.accessToken,
+  ...(session.refreshToken ? { refreshToken: session.refreshToken } : {}),
+});
+
+export const sameTokens = (a: unknown, b: KeychainTokens): boolean => {
+  if (!a || typeof a !== 'object') return false;
+  const t = a as Partial<KeychainTokens>;
+  return (
+    t.userId === b.userId &&
+    t.deviceId === b.deviceId &&
+    t.accessToken === b.accessToken &&
+    (t.refreshToken ?? undefined) === (b.refreshToken ?? undefined)
+  );
+};
+
+const withTimeout = <T>(p: Promise<T>, ms: number): Promise<T> =>
+  new Promise<T>((resolve, reject) => {
+    const timer = setTimeout(() => reject(new Error('keychain timed out')), ms);
+    p.then(
+      (v) => {
+        clearTimeout(timer);
+        resolve(v);
+      },
+      (e) => {
+        clearTimeout(timer);
+        reject(e);
+      },
+    );
+  });
+
+const errorText = (e: unknown): string =>
+  (e instanceof Error ? e.message : String(e)).slice(0, 200);
+
+/**
+ * Bring the keychain in line with `session` (null = no session). Reads first
+ * and only writes when the stored copy differs, then verifies by reading back.
+ */
+export const syncKeychain = async (
+  invoke: KeychainInvoke,
+  session: Session | null,
+  timeoutMs = KEYCHAIN_TIMEOUT_MS,
+): Promise<KeychainMirrorStatus> => {
+  // A desktop build without the commands (older than this feature) rejects
+  // the call: that is "not supported", not an error to show the user.
+  let supported: unknown;
+  try {
+    supported = await withTimeout(invoke('secure_session_supported'), timeoutMs);
+  } catch {
+    supported = false;
+  }
+  if (supported !== true) return { state: 'unsupported' };
+  try {
+    if (!session) {
+      await withTimeout(invoke('secure_session_clear'), timeoutMs);
+      return { state: 'cleared' };
+    }
+    const tokens = tokensOf(session);
+    const stored = await withTimeout(invoke('secure_session_get'), timeoutMs);
+    if (sameTokens(stored, tokens)) return { state: 'ok' };
+    await withTimeout(invoke('secure_session_set', { tokens }), timeoutMs);
+    const back = await withTimeout(invoke('secure_session_get'), timeoutMs);
+    if (!sameTokens(back, tokens)) return { state: 'error', error: 'read-back did not match' };
+    return { state: 'ok' };
+  } catch (e) {
+    return { state: 'error', error: errorText(e) };
+  }
+};
+
+let status: KeychainMirrorStatus = { state: 'idle' };
+const statusListeners = new Set<(s: KeychainMirrorStatus) => void>();
+const setStatus = (next: KeychainMirrorStatus): void => {
+  status = next;
+  statusListeners.forEach((cb) => cb(next));
+};
+
+export const getKeychainMirrorStatus = (): KeychainMirrorStatus => status;
+
+let started = false;
+
+/** Start mirroring (desktop only; call once at boot). */
+export const startKeychainMirror = (invoke: KeychainInvoke | undefined): void => {
+  if (!invoke || started) return;
+  started = true;
+  let chain: Promise<unknown> = Promise.resolve();
+  const enqueue = (session: Session | null) => {
+    chain = chain.then(async () => setStatus(await syncKeychain(invoke, session)));
+  };
+  enqueue(getFallbackSession() ?? null);
+  onSessionPersisted((session) => enqueue(session));
+};
+
+export const useKeychainMirrorStatus = (): KeychainMirrorStatus => {
+  const [value, setValue] = useState(status);
+  useEffect(() => {
+    setValue(status);
+    statusListeners.add(setValue);
+    return () => {
+      statusListeners.delete(setValue);
+    };
+  }, []);
+  return value;
+};

src/app/state/sessions.test.ts

@@ -432,3 +432,20 @@ test('subscribeSessionChanges ignores unrelated storage keys', () => {
   listeners.forEach((cb) => cb({ key: 'some_unrelated_preference' }));
   assert.equal(fired, false);
 });
+
+test('onSessionPersisted: told about writes and removals; a throwing listener is harmless', async () => {
+  installStorage();
+  const { onSessionPersisted } = await import('./sessions');
+  const seen: (string | null)[] = [];
+  const offBad = onSessionPersisted(() => {
+    throw new Error('boom');
+  });
+  const off = onSessionPersisted((s) => seen.push(s ? s.accessToken : null));
+  setFallbackSession('tok-a', 'DEV', '@a:hs', 'https://hs', { refreshToken: 'ref-a' });
+  removeFallbackSession();
+  off();
+  offBad();
+  setFallbackSession('tok-b', 'DEV', '@a:hs', 'https://hs');
+  assert.deepEqual(seen, ['tok-a', null]);
+  assert.equal(getFallbackSession()?.accessToken, 'tok-b', 'write still happened');
+});

src/app/state/sessions.ts

@@ -233,6 +233,27 @@ export type SessionStoreName = {
 //   crypto: 'crypto-store',
 // } as const;
 
+// [Gitea #105] Listeners told about every session write in THIS tab (login,
+// token rotation) and removal (logout), e.g. the desktop keychain mirror.
+// A throwing listener never breaks the write.
+type PersistListener = (session: Session | null) => void;
+const persistListeners = new Set<PersistListener>();
+const notifyPersisted = (session: Session | null): void => {
+  persistListeners.forEach((cb) => {
+    try {
+      cb(session);
+    } catch {
+      /* listener errors must not affect login/logout */
+    }
+  });
+};
+export const onSessionPersisted = (cb: PersistListener): (() => void) => {
+  persistListeners.add(cb);
+  return () => {
+    persistListeners.delete(cb);
+  };
+};
+
 // Persist the session. Writes the atomic blob FIRST (so the consistent,
 // never-torn copy is established before the multi-key legacy write), then
 // dual-writes the legacy keys for rollback safety. Signature is unchanged —
@@ -249,6 +270,7 @@ export function setFallbackSession(
   localStorage.setItem(SESSION_BLOB_KEY, JSON.stringify(persisted));
   // Dual-write the legacy keys (removal of this half is a future release).
   writeLegacyKeys(persisted);
+  notifyPersisted(sessionFromPersisted(persisted));
 }
 
 // Clear BOTH the atomic blob and every legacy key so no reader (blob-preferring
@@ -257,6 +279,7 @@ export const removeFallbackSession = () => {
   localStorage.removeItem(SESSION_BLOB_KEY);
   Object.values(LEGACY_KEYS).forEach((key) => localStorage.removeItem(key));
   Object.values(OIDC_KEYS).forEach((key) => localStorage.removeItem(key));
+  notifyPersisted(null);
 };
 
 // Read the session, preferring the atomic blob. If the blob is absent or

src/app/utils/clockSkew.test.ts

@@ -8,44 +8,96 @@ import {
   formatSkew,
 } from './clockSkew';
 
-// A live event received when the local clock is `skew` ms ahead of the server:
-// origin_server_ts = T (server clock), age = a, localTimestamp = (T + a + skew) - a.
-const feed = (m: ClockSkewMonitor, skew: number, age = 500, t = 1_700_000_000_000) =>
-  m.sample(t, age, t + skew);
+const T = 1_700_000_000_000;
 
-test('needs three samples, then reports the median with direction', () => {
+/**
+ * A live event received `atSec` seconds into the test, when the local clock is
+ * `skew` ms off the server and the response took `delay` ms to arrive:
+ * localTimestamp − origin_server_ts = skew + delay.
+ */
+const feed = (m: ClockSkewMonitor, skew: number, atSec = 0, delay = 0, wallJump = 0) =>
+  m.sample(T, 500, T + skew + delay, { wall: T + atSec * 1000 + wallJump, mono: atSec * 1000 });
+
+test('behind: reported as soon as there are three samples', () => {
   const m = new ClockSkewMonitor();
-  assert.equal(feed(m, 60_000).skewMs, null);
-  assert.equal(feed(m, 61_000).skewMs, null);
-  const s = feed(m, 59_000);
-  assert.equal(s.skewMs, 60_000);
+  assert.equal(feed(m, -60_000, 0).skewMs, null);
+  assert.equal(feed(m, -61_000, 1).skewMs, null);
+  const s = feed(m, -59_000, 2);
+  assert.equal(s.skewMs, -61_000);
   assert.equal(s.warning, true);
-  assert.equal(formatSkew(s.skewMs!), '60 seconds ahead');
+  assert.equal(formatSkew(s.skewMs!), '61 seconds behind');
 });
 
-test('one bad sample cannot trip the warning (median) and hysteresis clears only under 15 s', () => {
+test('ahead: only once it has held for a minute', () => {
   const m = new ClockSkewMonitor();
-  feed(m, 1000);
-  feed(m, 1500);
-  assert.equal(feed(m, 90_000).warning, false); // outlier
-  assert.equal(m.getState().skewMs, 1500);
+  feed(m, 60_000, 0);
+  feed(m, 60_000, 10);
+  assert.equal(feed(m, 60_000, 20).warning, false);
+  assert.equal(m.getState().skewMs, 60_000);
+  assert.equal(feed(m, 60_000, 59).warning, false);
+  assert.equal(feed(m, 60_000, 61).warning, true);
+});
 
+test('server stall (2026-09-29): a burst of late events does not read as a wrong clock', () => {
+  const m = new ClockSkewMonitor();
+  // Normal traffic, then the homeserver stalls and one /sync arrives 30 s late
+  // with a pile of events, then normal traffic again.
+  feed(m, 200, 0);
+  feed(m, 150, 5);
+  feed(m, 300, 10);
+  [1, 2, 3, 4, 5, 6].forEach(() => feed(m, 0, 130, 31_000));
+  assert.equal(m.getState().warning, false);
+  assert.ok(m.getState().skewMs! < 1000);
+
+  // Fresh client whose first samples are all from the late burst.
+  const fresh = new ClockSkewMonitor();
+  [1, 2, 3, 4, 5, 6].forEach(() => feed(fresh, 0, 0, 31_000));
+  assert.equal(fresh.getState().warning, false);
+  // …and the next timely event brings the estimate back down.
+  feed(fresh, 0, 70, 100);
+  assert.equal(fresh.getState().warning, false);
+  assert.equal(fresh.getState().skewMs, 100);
+});
+
+test('slow deliveries mixed with fast ones: the fastest one wins', () => {
+  const m = new ClockSkewMonitor();
+  [0, 20, 40, 60, 80].forEach((at, i) => feed(m, 45_000, at, i === 2 ? 0 : 20_000));
+  assert.equal(m.getState().skewMs, 45_000);
+  assert.equal(m.getState().warning, true);
+});
+
+test('hysteresis: once on, clears only under 15 s', () => {
   const w = new ClockSkewMonitor();
-  [40_000, 41_000, 39_000, 40_000, 40_000].forEach((s) => feed(w, s));
+  [0, 1, 2].forEach((at) => feed(w, -40_000, at));
   assert.equal(w.getState().warning, true);
-  // drifting down to 20 s: still >= 15 s → stays on
-  [20_000, 20_000, 20_000, 20_000, 20_000].forEach((s) => feed(w, s));
+  // Samples expire after 5 minutes; drifting to -20 s keeps it on (>= 15 s).
+  [400, 401, 402].forEach((at) => feed(w, -20_000, at));
+  assert.equal(w.getState().skewMs, -20_000);
   assert.equal(w.getState().warning, true);
-  [10_000, 10_000, 10_000, 10_000, 10_000].forEach((s) => feed(w, s));
+  [800, 801, 802].forEach((at) => feed(w, -10_000, at));
   assert.equal(w.getState().warning, false);
 });
 
+test('fixing the local clock starts the measurement afresh', () => {
+  const m = new ClockSkewMonitor();
+  [0, 1, 2].forEach((at) => feed(m, -14 * 60_000, at));
+  assert.equal(m.getState().warning, true);
+  // The user sets the clock forward 14 minutes: wall jumps vs the monotonic clock.
+  const jump = 14 * 60_000;
+  feed(m, 0, 10, 0, jump);
+  assert.equal(m.getState().warning, false);
+  assert.equal(m.getState().skewMs, null);
+  feed(m, 0, 11, 0, jump);
+  feed(m, 0, 12, 0, jump);
+  assert.equal(m.getState().skewMs, 0);
+  assert.equal(m.getState().warning, false);
+});
+
 test('stale or missing age is ignored (cache replay must not read as skew)', () => {
   const m = new ClockSkewMonitor();
-  const t = 1_700_000_000_000;
-  m.sample(t, undefined, t + 3_600_000);
-  m.sample(t, 40 * 24 * 60 * 60 * 1000, t + 3_600_000);
-  m.sample(t, -5, t);
+  m.sample(T, undefined, T + 3_600_000);
+  m.sample(T, 40 * 24 * 60 * 60 * 1000, T + 3_600_000);
+  m.sample(T, -5, T);
   assert.equal(m.getState().skewMs, null);
 });
 
@@ -53,10 +105,7 @@ test('subscribe fires on change only; reset clears', () => {
   const m = new ClockSkewMonitor();
   const seen: (number | null)[] = [];
   m.subscribe((s) => seen.push(s.skewMs));
-  feed(m, -120_000);
-  feed(m, -120_000);
-  feed(m, -120_000);
-  feed(m, -120_000);
+  [0, 1, 2, 3].forEach((at) => feed(m, -120_000, at));
   assert.deepEqual(seen, [-120_000]);
   assert.equal(formatSkew(-120_000), '2 minutes behind');
   m.reset();

src/app/utils/clockSkew.ts

@@ -22,8 +22,23 @@
 
 export const SKEW_WARN_MS = 30_000;
 export const SKEW_CLEAR_MS = 15_000;
-export const SKEW_SAMPLES = 5;
 export const SKEW_MIN_SAMPLES = 3;
+/** Samples older than this are forgotten. */
+export const SKEW_WINDOW_MS = 5 * 60 * 1000;
+export const SKEW_MAX_SAMPLES = 30;
+/**
+ * "Ahead" must hold across samples received at least this far apart.
+ *
+ * Incident 2026-09-29: the homeserver's host ran out of memory and stalled for
+ * ~2 minutes; the /sync that finally went out carried events whose `age` was
+ * computed ~30 s before it arrived, so every client read "your clock is 30 s
+ * ahead" — while the real problem was the server. A late delivery can only make
+ * the local clock look AHEAD (never behind), so the estimate is the LOWEST
+ * recent sample (the one delivered fastest), and "ahead" has to persist across
+ * a minute of fresh samples before it is reported. "Behind" can't come from a
+ * delay and is reported as soon as there are enough samples.
+ */
+export const SKEW_AHEAD_SPAN_MS = 60_000;
 /**
  * Sanity cap on `age`. Old events are still valid samples (the server computes
  * `age` at response time, so `ts + age` is its clock regardless of the event's
@@ -38,14 +53,21 @@ export type ClockSkewState = {
   warning: boolean;
 };
 
-const median = (xs: number[]): number => {
-  const s = [...xs].sort((a, b) => a - b);
-  const mid = Math.floor(s.length / 2);
-  return s.length % 2 ? s[mid] : (s[mid - 1] + s[mid]) / 2;
+/** A wall-clock change larger than this (vs the monotonic clock) resets the samples. */
+export const CLOCK_JUMP_MS = 5_000;
+
+type Sample = { skew: number; at: number };
+
+const currentClock = (): { wall: number; mono: number } => {
+  const wall = Date.now();
+  const mono = typeof performance !== 'undefined' ? performance.now() : wall;
+  return { wall, mono };
 };
 
 export class ClockSkewMonitor {
-  private samples: number[] = [];
+  private samples: Sample[] = [];
+
+  private clockOffset: number | undefined;
 
   private state: ClockSkewState = { skewMs: null, warning: false };
 
@@ -64,25 +86,47 @@ export class ClockSkewMonitor {
 
   /**
    * Feed one live event. `originServerTs` + `age` come from the event;
-   * `localTimestamp` is the SDK's `Date.now() − age` at construction.
+   * `localTimestamp` is the SDK's `Date.now() − age` at construction; `clock`
+   * is when the sample was taken: wall clock and a monotonic clock
+   * (performance.now()), so samples are aged by real elapsed time and a change
+   * of the local clock (someone fixing it) starts the measurement afresh.
+   * Only feed events stamped by OUR homeserver: another server's
+   * `origin_server_ts` carries that server's clock.
    * Returns the new state (unchanged object when nothing moved).
    */
   public sample(
     originServerTs: number,
     age: number | undefined,
     localTimestamp: number,
+    clock: { wall: number; mono: number } = currentClock(),
   ): ClockSkewState {
     if (age === undefined || !Number.isFinite(age) || age < 0 || age > SKEW_MAX_AGE_MS) {
       return this.state;
     }
     if (!Number.isFinite(originServerTs) || !Number.isFinite(localTimestamp)) return this.state;
-    this.samples.push(localTimestamp - originServerTs);
-    if (this.samples.length > SKEW_SAMPLES) this.samples.shift();
+    const now = clock.mono;
+    const offset = clock.wall - clock.mono;
+    if (this.clockOffset !== undefined && Math.abs(offset - this.clockOffset) > CLOCK_JUMP_MS) {
+      // The local clock was changed: earlier samples measured the old clock.
+      this.reset();
+    }
+    this.clockOffset = offset;
+    this.samples.push({ skew: localTimestamp - originServerTs, at: now });
+    this.samples = this.samples.filter((s) => now - s.at <= SKEW_WINDOW_MS);
+    if (this.samples.length > SKEW_MAX_SAMPLES) this.samples.shift();
     if (this.samples.length < SKEW_MIN_SAMPLES) return this.state;
 
-    const skewMs = median(this.samples);
+    // Delivery delay only ever adds to a sample: the smallest is the truest.
+    const skewMs = Math.min(...this.samples.map((s) => s.skew));
     const abs = Math.abs(skewMs);
-    const warning = this.state.warning ? abs >= SKEW_CLEAR_MS : abs > SKEW_WARN_MS;
+    let warning: boolean;
+    if (this.state.warning) warning = abs >= SKEW_CLEAR_MS;
+    else if (skewMs < -SKEW_WARN_MS) warning = true;
+    else if (skewMs > SKEW_WARN_MS) {
+      // Ahead: only if the fastest-delivered samples stayed high for a minute.
+      const span = now - Math.min(...this.samples.map((s) => s.at));
+      warning = span >= SKEW_AHEAD_SPAN_MS;
+    } else warning = false;
     if (skewMs === this.state.skewMs && warning === this.state.warning) return this.state;
     this.state = { skewMs, warning };
     this.listeners.forEach((cb) => cb(this.state));
@@ -91,6 +135,7 @@ export class ClockSkewMonitor {
 
   public reset(): void {
     this.samples = [];
+    this.clockOffset = undefined;
     if (this.state.skewMs !== null || this.state.warning) {
       this.state = { skewMs: null, warning: false };
       this.listeners.forEach((cb) => cb(this.state));

src/index.tsx

@@ -17,10 +17,16 @@ import App from './app/pages/App';
 import './app/i18n';
 import { pushSessionToSW } from './sw-session';
 import { getFallbackSession } from './app/state/sessions';
+import { startKeychainMirror } from './app/state/keychainMirror';
+import { tauriInvoke } from './app/hooks/useTauri';
 import { cleanupSearchCacheIfSignedOut } from './client/initMatrix';
 
 document.body.classList.add(configClass, varsClass);
 
+// [Gitea #105] Desktop: keep a copy of the login tokens in the OS keychain
+// (step 1: mirror only; the session is still read from localStorage).
+startKeychainMirror(tauriInvoke());
+
 // Register Service Worker
 // Service workers only register on http(s) pages. The desktop app loads from
 // `tauri://localhost` in debug builds (and on any platform where the localhost