adk-session

Session management and state persistence for Rust Agent Development Kit (ADK-Rust) agents.

Overview

adk-session provides session and state management for the Rust Agent Development Kit (ADK-Rust):

InMemorySessionService - Simple in-memory session storage
SqliteSessionService - SQLite-backed persistence (sqlite feature)
PostgresSessionService - PostgreSQL-backed persistence (postgres feature)
RedisSessionService - Redis-backed persistence (redis feature)
MongoSessionService - MongoDB-backed persistence (mongodb feature)
Neo4jSessionService - Neo4j-backed persistence (neo4j feature)
FirestoreSessionService - Firestore-backed persistence (firestore feature)
VertexAiSessionService - Vertex AI Session API backend (vertex-session feature)
Schema Migrations - Versioned, forward-only migrations for all database backends

Installation

[dependencies]
adk-session = "0.4"

Or use the meta-crate:

[dependencies]
adk-rust = { version = "0.4", features = ["sessions"] }

Quick Start

use adk_session::{InMemorySessionService, SessionService, CreateRequest, KEY_PREFIX_USER};
use serde_json::json;
use std::collections::HashMap;

let service = InMemorySessionService::new();

let mut initial_state = HashMap::new();
initial_state.insert(format!("{}name", KEY_PREFIX_USER), json!("Alice"));

let session = service.create(CreateRequest {
    app_name: "my_app".to_string(),
    user_id: "user_123".to_string(),
    session_id: None,
    state: initial_state,
}).await?;

let name = session.state().get("user:name");

State Prefixes

Prefix	Purpose	Persistence
`user:`	User preferences	Across sessions
`app:`	Application state	Application-wide
`temp:`	Temporary data	Current turn only

Feature Flags

Feature	Backend	Description
`sqlite`	SQLite	Single-node persistence via sqlx
`database`	SQLite	Alias for `sqlite` (backward compat)
`postgres`	PostgreSQL	Production-grade relational persistence
`redis`	Redis	Low-latency in-memory persistence via fred
`mongodb`	MongoDB	Document-oriented persistence
`neo4j`	Neo4j	Graph database persistence
`firestore`	Firestore	Google Cloud Firestore persistence
`vertex-session`	Vertex AI	Vertex AI Session API backend

# SQLite
adk-session = { version = "0.4", features = ["sqlite"] }

# PostgreSQL
adk-session = { version = "0.4", features = ["postgres"] }

# Redis
adk-session = { version = "0.4", features = ["redis"] }

Schema Migrations

All database backends (SQLite, PostgreSQL, MongoDB, Neo4j) include a versioned migration system. Migrations are forward-only, idempotent, and tracked in a _schema_migrations registry table.

use adk_session::SqliteSessionService;

let service = SqliteSessionService::new("sqlite:sessions.db").await?;

// Run all pending migrations
service.migrate().await?;

// Check current schema version
let version = service.schema_version().await?;
println!("Schema version: {version}");

Each backend detects pre-existing tables (baseline detection) and registers them as already applied, so migrate() is safe to call on both fresh and existing databases.

Rename: DatabaseSessionService → SqliteSessionService

As of v0.4.0, DatabaseSessionService has been renamed to SqliteSessionService to accurately reflect that it is a SQLite-only backend. A deprecated type alias is provided for backward compatibility:

// Old (still compiles with a deprecation warning)
use adk_session::DatabaseSessionService;

// New
use adk_session::SqliteSessionService;

Related Crates

adk-rust - Meta-crate with all components
adk-core - Core Session trait
adk-runner - Uses sessions for execution

License

Apache-2.0

Part of ADK-Rust

This crate is part of the ADK-Rust framework for building AI agents in Rust.

adk-session 0.4.0