SessionDataStore

Opaque per-session data for the run loop.

SessionDataStore holds key-value data that travels with a session and is available to every tool and adapter during a turn. It is separate from SessionStore (which holds the canonical message history) because:

• It is opaque to the model.
• It does not need transactional semantics.
• It is small (kilobytes per session, not megabytes).

The full file is src/runtime/session_data_store.rs.

API

#[async_trait]
pub trait SessionDataStore: Send + Sync {
    async fn get(&self, session_id: Uuid, key: &str) -> Result<Option<Vec<u8>>, SessionDataError>;
    async fn set(&self, session_id: Uuid, key: &str, value: Vec<u8>) -> Result<(), SessionDataError>;
    async fn delete(&self, session_id: Uuid, key: &str) -> Result<(), SessionDataError>;
    async fn list_keys(&self, session_id: Uuid) -> Result<Vec<String>, SessionDataError>;
    async fn health_check(&self) -> Result<(), SessionDataError>;
}

Backends

• MemorySessionDataStore — in-process; default.
• FileSessionDataStore — file-based; default in production.
• RedisSessionDataStore — feature redis.

Use cases

• Cached user preferences (theme, language) that are read on every turn.
• Tool-specific state (e.g. a draft document the user is editing).
• A/B testing flags that change the prompt strategy.

See also

• RuntimeInvocation — the consumer.
• SessionStore — the canonical session data.