diff --git a/src/app/features/settings/general/General.tsx b/src/app/features/settings/general/General.tsx
index 4601e9e88..898c1a22d 100644
--- a/src/app/features/settings/general/General.tsx
+++ b/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
diff --git a/src/app/state/keychainMirror.test.ts b/src/app/state/keychainMirror.test.ts
new file mode 100644
index 000000000..d3413244a
--- /dev/null
+++ b/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);
+});
diff --git a/src/app/state/keychainMirror.ts b/src/app/state/keychainMirror.ts
new file mode 100644
index 000000000..2ccdc38cf
--- /dev/null
+++ b/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;
+};
diff --git a/src/app/state/sessions.test.ts b/src/app/state/sessions.test.ts
index e54075237..0235a1736 100644
--- a/src/app/state/sessions.test.ts
+++ b/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');
+});
diff --git a/src/app/state/sessions.ts b/src/app/state/sessions.ts
index 85a03f203..2c00061c7 100644
--- a/src/app/state/sessions.ts
+++ b/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
diff --git a/src/index.tsx b/src/index.tsx
index 63631bc7d..528fd59c9 100644
--- a/src/index.tsx
+++ b/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