Every backup writes vaultik-destination.txt at the destination root.
While the local index holds snapshots, a destination without it is
not present: snapshot create refuses before writing, prune and
snapshot purge fail, and snapshot list and snapshot remove act as for
a destination that cannot be listed. remote nuke deletes it last. The
file:// backend no longer creates its destination directory and checks
for it on every write; that protects a directory on a removable
volume, not a mount point.
Tests back up into directories that exist; fixtures standing for a
written destination carry the marker; two tests check they get past
it.
Judgement call: the marker is rewritten on every backup.
Deviation: for the complexity limit, two blocks moved, unchanged, into
snapshotNamesToCreate and confirmRemoveSnapshot.
Model: opus-5-5
An object holding just the age header and its 16-byte nonce decrypts without error: the truncated read surfaces as io.ErrUnexpectedEOF at the age layer, which the zstd decoder maps to a clean EOF at frame start. blobgen then reported zero bytes and no error, so a truncated stream was indistinguishable from a valid empty one, and the metadata database export slipped through -- restore built a fresh schema on the empty file and reported success.
blobgen.Reader.Read now, on EOF, reads once more from the age reader and surfaces io.ErrUnexpectedEOF unless that read is (0, io.EOF), the state a genuine end leaves. downloadSnapshotDB additionally rejects a zero-length decrypted database before any schema is built.
Model: opus-4-8