The tx-history cache was only ever used from the UI thread and had no
locking. To let snapshots be written from a background thread:
- every SQL statement runs under one database mutex and the key fields
under a second one, taken after it and never held across I/O or the
key derivation;
- a write is a self-contained, move-only SnapshotJob holding the rows
and a private copy of the key, which is wiped after the write or when
a job never runs; the JSON build and encryption hold no lock;
- a job with an all-zero key is refused instead of overwriting a good
snapshot with one nobody can read;
- the prune after a write also keeps the wallet unlocked now, so a late
job for the previous wallet can't delete the salt of the one just
switched to;
- keyId() gives a non-reversible tag of the installed key, so a
passphrase change can be told from a re-unlock with the same one.
replace() stays a synchronous wrapper with the same result. A failed
INSERT is now logged.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
DanSandClaude Opus 5.5
c0568eb930