A notification feature is mostly things that correctly do NOT happen, and each of
these is invisible until it goes wrong in production: a departed member and a
revoked guest are not recipients; a mute subtracts per Team and leaves the user's
other Teams alone; the author of a post never receives the notification about it;
forums switched off silences the forum streams including the digest; a Team's
first roster wakes nobody; a failed send does not stamp `last_digest_at`.
Two real defects came out of writing them.
`Number(null)` is 0 and 0 is an integer, so a null in a caller's id list survived
`filter(Number.isInteger)` and rode into an IN clause as user id 0. No row has id
0, so it was harmless — which is exactly why it would never have been noticed.
Fixed in all three places that filter ids.
`recipientIds: db.recipientIds` in the model captured the function OBJECT at
require time, so the layer below could never be substituted. That is not only
untestable; it means the model was not really the seam it claimed to be. Wrapped
so `db.x` resolves at call time.
The registries catalog assertion is now an exact five-element list, so a
shard-content stream creeping back into core's registration fails here rather
than shipping.
Co-Authored-By: Claude <noreply@anthropic.com>
