SDK Kit C ABI

The stable C boundary used by BoutiqueDB to call into the embedded database engine.

SDK-kit C ABI

BoutiqueDB links the engine through the sdk-kit C ABI (turso.h). This is the official surface for building language bindings, and it is the only surface that exposes async_io, per-open experimental features, and encryption.

Why sdk-kit instead of sqlite3.h

The bindings/c crate implements the SQLite 3 C API for compatibility. It is useful for dropping BoutiqueDB into existing SQLite code, but it has limits:

• The only experimental toggle is global turso_enable_experimental(), which enables a subset of flags.
• It cannot set async_io per open.
• It cannot configure encryption keys per database.

sdk-kit (sdk-kit/turso.h) exposes a small, explicit C surface designed for bindings.

Key types and functions

Database lifecycle

turso_database_config_t config = {
  .path = ":memory:",
  .experimental_features = "views,index_method",
  .async_io = true,
  .vfs = NULL,
  .encryption_cipher = NULL,
  .encryption_hexkey = NULL
};

turso_database_new(&config, &db, &error);
turso_database_open(db, &error);
turso_database_connect(db, &conn, &error);

Statement loop

for (;;) {
  turso_status_t st = turso_statement_step(stmt, &error);
  if (st.code == TURSO_ROW) { /* read row */ }
  else if (st.code == TURSO_DONE) { break; }
  else if (st.code == TURSO_IO) { turso_statement_run_io(stmt, &error); }
  else { /* error */ }
}

Status codes

• TURSO_OK, TURSO_DONE, TURSO_ROW
• TURSO_IO — drive I/O and resume.
• TURSO_BUSY — conflict or lock contention.
• TURSO_BUSY_SNAPSHOT — MVCC snapshot conflict.
• TURSO_ERROR — general error; check error_opt_out.

Swift mapping

TursoKit wraps these C calls into Swift types:

C type	Swift type
turso_database_t	TursoDatabase
turso_connection_t	TursoConnection
turso_statement_t	TursoStatement
turso_value_t	TursoValue

TursoOpenOptions maps to turso_database_config_t.

For the full C API, see sdk-kit/turso.h in the engine repo.