[grade=B] fix(auth): reuse valid session for cross-host SSO

status/tests/auth-gate-return-url.test.js

@@ -93,3 +93,41 @@ test('same-origin and tokenless destinations keep their direct URL', () => {
   assert.equal(buildHandoffTarget('/settings', 'one-time'), 'https://status.sami/settings');
   assert.equal(buildHandoffTarget('https://router.sami/config', ''), 'https://router.sami/config');
 });
+
+test('an existing status.sami session returns to a service without another TOTP prompt', async () => {
+  const query = new URLSearchParams({ auth: 'required', return: 'https://plex.sami/web/' });
+  let scheduled;
+  let redirected;
+  const location = {
+    origin: 'https://status.sami',
+    pathname: '/',
+    search: `?${query.toString()}`,
+    replace(value) { redirected = value; },
+  };
+  const context = {
+    URL,
+    URLSearchParams,
+    SITE: { tld: '.sami' },
+    sessionStorage: { setItem() {} },
+    document: { getElementById() { return null; } },
+    setTimeout(fn) { scheduled = fn; },
+    console,
+    fetch: async (url) => {
+      assert.equal(url, '/api/v1/auth/sso-handoff');
+      return { ok: true, json: async () => ({ success: true, ssoToken: 'existing-session-token' }) };
+    },
+    window: {
+      location,
+      history: { replaceState() {} },
+    },
+  };
+  context.window.window = context.window;
+  vm.runInNewContext(source, context, { filename: 'auth-gate.js' });
+
+  assert.equal(typeof scheduled, 'function');
+  await scheduled();
+  assert.equal(
+    redirected,
+    'https://plex.sami/dashcaddy-sso?token=existing-session-token&return=%2Fweb%2F',
+  );
+});