FYI, I've once had few long-lived connection with wal, and wal file just goes exploded. Turns out sqlite won't truncate the wal if there are open connections.
Using WAL2 should make that problem better. It has two WAL files it alternates between when making writes, so the system has an opportunity to check point the WAL file not in use.
infamia|7 months ago
https://sqlite.org/src/doc/wal2/doc/wal2.md