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