Hooks, backup & introspection

Lower-level driver capabilities. Most are connection-level — install them on a pinned connection, because database/sql’s pool fan-out makes “install once on db” fragile.

Per-connection update / authorizer / commit / rollback / pre-update / trace callbacks:

db.SetMaxOpenConns(1)
sc, _ := db.Conn(ctx)
sc.Raw(func(dc any) error {
  c := dc.(*sqlite.Conn)
  c.RegisterUpdateHook(func(op int, dbName, table string, rowid int64) { /* ... */ })
  c.RegisterAuthorizer(func(op int, a1, a2, dbName, trig string) int { return sqlite.SQLITE_OK })
  return c.SetTrace(&sqlite.TraceConfig{EventMask: sqlite.TraceStmt, Callback: /* ... */})
})
// Drive traffic through sc.ExecContext, NOT db.Exec.

Runnable: examples/features/advanced/hooks/ (full update / authorizer / commit / trace round-trip with the conn-pinning idiom).

• (*Conn).Backup(destSchema, srcConn, srcSchema) — the mattn-compat factory driving sqlite3_backup_* against an open destination connection (caller-owned).
• sqlite.Serialize(ctx, db) []byte snapshots an in-memory database into a byte buffer; sqlite.Deserialize(ctx, db, buf) restores it. Useful for ship-a-DB-as-state and state-machine tests.

Runnable: examples/features/advanced/backup/.

On *sqlite.Conn: TableColumnMetadata (decltype / collation / PK / autoinc without a SELECT), Status (SQLite cache/lookaside counters), TxnState, StmtCacheStats (prepared-statement LRU hit/miss/eviction), CollationNeeded / AnyCollationNeeded (define collations lazily). On *sqlite.Stmt: Readonly, Status (VM-step / sort / fullscan counters). The *FunctionContext passed to a UDF exposes result/argument subtypes and per-argument aux-data caching (SetAuxData / GetAuxData) — see examples/features/advanced/udf-context/.

WAL control (WALCheckpoint, WALAutoCheckpoint, RegisterWALHook), snapshots (GetSnapshot / OpenSnapshot / SnapshotRecover), the progress handler, and db_config security flags round out the conn-level surface. Full matrix: dev/coverage/conn.md.