A moment after signing in, the app asks whether to turn notifications on, once per device and only where the server offers push and the device is not signed up yet. Turning them on goes the way of the settings card, which brings up the system's question. iOS asked only when someone found that card.
The app subscribes to Web Push like a browser, only the app makes the
subscription: it asks for permission, registers with APNs and keeps its own
P-256 key pair and auth secret in a keychain group a notification extension
can share. The endpoint is liketrek's relay for this device's token, so the
server encrypts exactly as for a browser and nobody on the way can read the
notification. The settings card, the test push, sign-in resync and the logout
teardown all take this path where the binary has nativePush; a tapped
notification opens the place it points at, also from a cold start.
The App ID has push enabled, the app carries the aps-environment and
keychain-group entitlements.
A fourth built-in channel next to email, webhook and ntfy. Browsers
register per device, the server encrypts per RFC 8291 and signs per RFC
8292 with node:crypto and sends only to known push services through the
SSRF guard. The event matrix decides per category what arrives by push;
admins switch the channel on under Notifications.
VAPID keys come from the environment or are generated once, only while
neither stored row exists, and kept encrypted. A pair that does not
decrypt or match is never overwritten and never swapped for another one:
push stays off with an error in the log and every device stays
registered until the key is fixed. The subject is VAPID_SUBJECT, then an
https APP_URL, then the project URL.
Only chat messages collapse into one notification per trip, and a
replacement still alerts. A 403 removes a device only after three
failures in a row; 404 and 410 remove it at once. Password change, reset
and an admin setting a password drop the user's devices with the other
credentials. The request log redacts subscriptions and endpoints, boot
errors print *** for every secret variable, and logout forgets the
device with a plain fetch so an expired session cannot redirect midway.
Addresses discussion #894.
Maurice