The avatar cache files written for Communication Notifications cannot be
deleted right after the handler returns (the system reads them lazily, e.g.
the Apple Watch fetching the image), and the NSE gets no dismissal callback.
Add best-effort, age-based cleanup that drops files older than 24 hours each
time a new avatar is written. Notifications are ephemeral, so any device that
needed an old file is long done. The cleanup tolerates concurrent NSE
instances removing the same file.
Chat notifications are upgraded to Communication Notifications and attach
the sender's avatar to the INPerson via downloadAvatarImage. The image was
built with INImage(imageData:), which renders on the iPhone but is not
relayed to paired devices like the Apple Watch. The Watch then falls back to
drawing a monogram from the sender's initials instead of the avatar.
Write the downloaded avatar bytes to a file in the shared App Group
container and back the INImage with INImage(url:) so the system can resolve
the image lazily across devices. Files are named by a stable hash of the
content-addressed thumbnail URL so notifications from the same sender reuse
one file.
Claude