fix(hub): an open application looks for new notifications when you come back

The page asked for the notification list at sign-in and at a token renewal,
and at no other time. A notification created after the application started,
such as a chat line the hub wrote 20 ms after the message, stayed unseen until
the next launch.

The hub has no channel to the page and is not polled on a timer, so the list
is asked for again on a gesture: the application returning to the foreground
(an Android phone included) and the home page, where the list is shown. Two
requests less than 30 s apart count as one.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

2 files changed, 77 insertions, 0 deletions

diff --git a/packages/meshbay-hub/src/meshbay_hub/static/app.js b/packages/meshbay-hub/src/meshbay_hub/static/app.js
index 2254a11..50bd8ac 100644
--- a/packages/meshbay-hub/src/meshbay_hub/static/app.js
+++ b/packages/meshbay-hub/src/meshbay_hub/static/app.js
@@ -43,6 +43,9 @@ import { InvitePage, JoinByLink } from './invite-page.js';
 // How often to look. Cheap — it reads a timestamp out of the token and almost
 // always does nothing.
 const TOKEN_CHECK_MS = 60000;
+// The least time between two askings for the notification list on somebody's
+// return: a gesture, never a timer, and two in a row are one question.
+const NOTIF_REFRESH_MS = 30000;
 const THEME_KEY = 'mb_theme';
 
 // ── Theme ────────────────────────────────────────────────────────────────────
@@ -980,10 +983,12 @@ function App() {
     hubFetch('/v1/hub/info').then(setHubInfo).catch(() => {});
   }, []);
 
+  const notifAskedAtRef = useRef(0);
   const fetchNotifications = useCallback(() => {
     if (!user || notifDisabled) {
       setNotifications([]); setUnreadCount(0); return;
     }
+    notifAskedAtRef.current = Date.now();
     // `unread_only`: clicking one is what dismisses it (see markRead), so a
     // read notification is a dismissed notification and must not come back on
     // the next launch. Without this the two halves disagreed — the click
@@ -1046,6 +1051,30 @@ function App() {
     syncPush(user).catch(() => {});
   }, [user]);
 
+  // The list used to be asked for at sign-in and then never, so an application
+  // left open showed nothing created after it started: a chat line the hub
+  // wrote within 20 ms of the message stayed unseen. The hub has no channel to
+  // the page, and is not polled on a timer, so the list is asked for again
+  // when somebody comes back to look: the application returning to the
+  // foreground (a phone included), and the home page, where it is shown.
+  const refreshNotifications = useCallback(() => {
+    if (Date.now() - notifAskedAtRef.current < NOTIF_REFRESH_MS) return;
+    fetchNotifications();
+  }, [fetchNotifications]);
+
+  useEffect(() => {
+    if (!user) return;
+    const onVisible = () => {
+      if (document.visibilityState === 'visible') refreshNotifications();
+    };
+    document.addEventListener('visibilitychange', onVisible);
+    return () => document.removeEventListener('visibilitychange', onVisible);
+  }, [user, refreshNotifications]);
+
+  useEffect(() => {
+    if (user && route === '/') refreshNotifications();
+  }, [user, route, refreshNotifications]);
+
   // The node this application ships, set up, started and linked for whoever
   // signs in (main.js `ensureNode`): installing it is all it should take.
   // Keyed on the account, not the session object -- the token rotates, and a
diff --git a/packages/meshbay-hub/tests/test_notification_refresh.py b/packages/meshbay-hub/tests/test_notification_refresh.py
new file mode 100644
index 0000000..9e41f0c
--- /dev/null
+++ b/packages/meshbay-hub/tests/test_notification_refresh.py
@@ -0,0 +1,48 @@
+"""
+An open application asks for the notification list again when somebody comes back.
+
+Reported live on 2026-10-09: a member posted in a group, the hub wrote the
+owner's notification 20 ms later, and the owner, whose application was open,
+never saw it. Nothing was broken on the hub or the node. The page asked for the
+list at sign-in (and at a token renewal, every few hours) and at no other time,
+so a notification created after the application started waited for the next
+launch.
+
+The hub has no channel to the page and is deliberately not polled on a timer,
+so the list is asked for again on a gesture: the application returning to the
+foreground, or the home page, where the list is shown. Two in a row are one
+question. These read the source; there is no browser for the SPA's state here.
+"""
+
+import re
+from pathlib import Path
+
+APP = (Path(__file__).resolve().parents[1] / "src" / "meshbay_hub" / "static"
+       / "app.js").read_text()
+
+
+def _block(start: str) -> str:
+    i = APP.index(start)
+    return APP[i:APP.index("\n  }, [", i)]
+
+
+def test_coming_back_to_the_application_asks_again():
+    listeners = [m.start() for m in re.finditer(r"addEventListener\('visibilitychange'", APP)]
+    bodies = [APP[APP.rfind("useEffect(", 0, i):i] for i in listeners]
+    assert any("refreshNotifications()" in b and "'visible'" in b for b in bodies), \
+        "no visibilitychange listener asks for the notification list"
+
+
+def test_the_home_page_asks_again():
+    assert re.search(r"if \(user && route === '/'\) refreshNotifications\(\);", APP)
+
+
+def test_two_askings_in_a_row_are_one_and_no_timer_asks():
+    refresh = _block("const refreshNotifications = useCallback(")
+    assert "NOTIF_REFRESH_MS" in refresh and "fetchNotifications()" in refresh
+    # The stamp is taken where the request leaves, so the sign-in fetch counts
+    # and the home page right after it does not ask a second time.
+    fetch = _block("const fetchNotifications = useCallback(")
+    assert "notifAskedAtRef.current = Date.now()" in fetch
+    for timer in re.finditer(r"setInterval\(([^,]+),", APP):
+        assert "otif" not in timer.group(1), "the notification list is polled on a timer"