Bucket.Put stores a body under a key, signed over its SHA-256; Bucket.List
pages through ListObjectsV2. A backup only adds and lists, so an
append-only key is enough. Keys are encoded once, exactly as signed, so
music paths with spaces, plus signs and accents reach the bucket intact.
A refusal names S3's code in words ("the secret key is wrong").
The signer is pinned to AWS's published GET Object, PUT Object and
ListObjects examples.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
The file is minstrel-<UTC stamp>.tar: manifest.json first, then
tables/<table>.jsonl, rows one per line in primary-key order. The run's
time lives only in the manifest and member headers are fixed, so a
deduplicating off-site copy stores unchanged tables once.
WriteFile writes to a hidden .part file, syncs it and renames it, so a
watched folder never shows half a backup. Read refuses anything that
isn't a whole backup: another format, a newer format version, a cut-off
file, or a member holding fewer rows than the manifest says.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
internal/backup names every table a backup holds, in parent-first order,
and every table it leaves out with the reason: what the server computes
from the music files, provider caches it fetches again, sign-ins and
one-time links, and logs of past runs. The library's identity rows travel
because every like, play and playlist entry hangs off a track id, and the
sync change feed travels because the apps' first sync reads it.
Sealed credentials are left out of the file, and so are the markers that
say tag and art enrichment are done, so a restored server asks for the
credentials again and redoes that work rather than believing it has it.
Snapshot reads one REPEATABLE READ, read-only transaction, each table in
primary-key order, keys sorted. Restore refuses an instance with accounts
or tracks and a backup from a newer schema, replaces seeded settings,
inserts by column intersection in batches, skips generated columns, and
carries serial sequences on past the restored ids.
Guards: every schema table is backed up or excluded; every backed-up
table comes after what it references and references nothing excluded;
every omitted column exists; a restore gives back the backup byte for byte.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>