Crate adk_session 

adk-session

Session management and state persistence for ADK agents.

Overview

This crate provides session and state management:

• InMemorySessionService - Simple in-memory session storage
• VertexAiSessionService - Vertex AI Session API backend (vertex-session feature)
• Session - Conversation session with state and events
• State - Key-value state with typed prefixes
• SessionService - Trait for custom session backends

Quick Start

use adk_session::InMemorySessionService;

let service = InMemorySessionService::new();

// Sessions are created and managed by the Runner
// State is accessed via the session

State Prefixes

ADK uses prefixes to organize state:

Prefix	Constant	Purpose
user:	KEY_PREFIX_USER	User preferences
app:	KEY_PREFIX_APP	Application state
temp:	KEY_PREFIX_TEMP	Temporary data

Re-exports

pub use event::Events;

pub use inmemory::InMemorySessionService;

pub use service::AppendEventRequest;

pub use service::CreateRequest;

pub use service::DeleteRequest;

pub use service::GetRequest;

pub use service::ListRequest;

pub use service::SessionService;

pub use session::KEY_PREFIX_APP;

pub use session::KEY_PREFIX_TEMP;

pub use session::KEY_PREFIX_USER;

pub use session::Session;

pub use state::ReadonlyState;

pub use state::State;

pub use state_utils::extract_state_deltas;

pub use state_utils::merge_states;

Modules

event

Event types and the Events trait for accessing session event history.

inmemory

In-memory session backend for testing and lightweight use cases.

migration

Schema migration utilities for database-backed session stores. Lightweight, embedded migration runner for SQL-backed session services.

service

Session service trait and request/response types.

session

The Session trait and state key prefix constants.

state

State access traits (State and ReadonlyState).

state_utils

Shared utilities for extracting and merging state deltas across backends. Shared state utility functions for session backends.

Structs

Event

Event represents a single interaction in a conversation. This struct embeds LlmResponse to match ADK-Go’s design pattern.

EventActions

Actions to apply as side effects of an event.