The connection settings were passed as `_journal_mode=`-style
parameters, which the SQLite driver drops without an error, so the
index ran in rollback-journal mode with no busy timeout. `snapshot
list` or `info` reading during a backup could make the backup's next
write fail with "database is locked". Both open paths now pass
`_pragma=` parameters; foreign keys moved there too.
With WAL on, rows committed to the open index can still be in the
-wal file, which a copy of the main file misses. The metadata export
now copies the index with VACUUM INTO, into an empty 0600 file.
The retry after a failed open no longer claims a TRUNCATE recovery; it
retries with the same settings.
Model: opus-5-5
The local index lists every backed-up path and chunk hash, but its file mode was left to the SQLite driver and the umask, so under a typical 022 umask a fresh index (and its -wal/-shm side files) landed world-readable. The snapshot export copied the index to snapshot.db with a permissive create as well.
provideDatabase now calls ensureIndexFileMode before opening the driver: it creates the index 0600 if missing and chmods an existing one to 0600. Doing this before the driver opens the file matters because SQLite gives its -wal and -shm files the mode of the main database file. The export copy is now created 0600. Tests under umask 022 cover a fresh index, an existing 0644 index, and the export copy.
Model: opus-4-8