Teammate mailbox and team-config writes use the newer storage layer when it's present.
What's wrong with this entry?
Mailbox writes, marking messages read, message pruning and team-config updates now go through a transactional storage update when the session has the newer storage backend, and fall back to the old lockfile-plus-atomic-write path when it does not.
- The new path retries when a lock looks suspect and separates contention from hard failures in telemetry.
- Hard failures surface as "Team file update failed (storage v5)".
- The old file-based mailbox read and clear helpers are gone.
Team file update failed (storage v5)
Strings lifted out of the shipped bundle, so the claim above can be checked against them.