Reusing the backup snapshot for sync had two bugs that would bite real use:
1. Deletions didn't propagate. exportInventory() filters isDeleted=false
(user backups are tombstone-free by design) and the JSON codec dropped
isDeleted (omitted on encode, hardcoded false on decode) — so deleting a
variety on one device never reached the others. Now the codec round-trips
isDeleted (emitted only when true, so backups stay byte-identical and it's
backward compatible), and a new exportForSync() includes tombstones. The
importer already merges them LWW-correctly.
2. Photos bloated events. The snapshot embeds photo bytes as base64, so a
real inventory would blow past relay event-size limits and sync would
silently fail. exportForSync() omits attachments entirely (photos stay
device-local; media sync is a separate, deferred concern).
buildSnapshot() now uses exportForSync(); backups keep using exportInventory
(photos in, tombstones out) unchanged.
Tests: a deletion replicates as a tombstone; the sync snapshot carries no
photo bytes while a sealed backup still does.
vjrj
b15f912ad8