Function spawn_wal_checkpoint_loop 

pub fn spawn_wal_checkpoint_loop(
    token: CancellationToken,
    wal_mstore: Arc<Store>,
    wal_filestore: Arc<FileStore>,
)

Periodic WAL checkpoint — prevents unbounded WAL file growth during long-running sessions. Runs every 30 minutes while the srv is up. busy_timeout=5000 (set at DB open) handles transient reader contention; partial truncate on contention is safe — the remainder is picked up on the next pass. (SPEC_WINDOWS_LIFECYCLE_ROBUSTNESS_2026_06_26 §4.E)