has_access_to_file granted access whenever the file was attached to a
shared chat the user could read, ignoring the requested access_type. A
read-only shared-chat recipient therefore satisfied write and delete
checks and could delete or mutate the chat owner's attached file. Gate
the shared-chat branch on read access, matching the channels branch
directly above it.
Co-authored-by: oxsignal <oxsignal@users.noreply.github.com>
Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
