Persistence layer for Sage agent checkpoints.

This crate provides durable storage for @persistent agent fields, enabling agents to recover their state after restarts, crashes, or process exits.

Backends

• sqlite (default): Local SQLite database
• postgres: PostgreSQL for production deployments
• file: JSON files for development/debugging

Example

use sage_persistence::{CheckpointStore, SqliteStore};

let store = SqliteStore::open(".sage/checkpoints.db").await?;
store.save("agent_key", "field", serde_json::json!(42)).await?;
let value = store.load("agent_key", "field").await?;