//! Live transaction snapshot and visibility support.
//!
//! The live engine is optimistic MVCC: `SnapshotManager` allocates xids,
//! `visibility` decides snapshot reads, and commit-time first-committer-wins
//! checks live in the runtime.
//!
//! # Isolation Levels
//!
//! - **Read Committed**: See committed changes from other transactions
//! - **Snapshot Isolation**: See consistent snapshot from transaction start
//! - **Serializable**: Serializable read/write conflict tracking with runtime commit validation
pub use IsolationLevel;
pub use ;
pub use is_visible;