title: Session API (Agent System)
description: "API reference for session management in JustAPI, the FastAPI alternative — Rust-backed agent session state management."
keywords: [session, fastapi alternative, justapi, session management, agent system, state management]

Session Object

Sessions provide durable per-client state storage backed by the Rust runtime. Sessions are identified by the justapi_session cookie or ?session= query parameter.

from justapi import Session

Properties & Methods

Usage

from justapi import JustAPIApp, Session

app = JustAPIApp()
app.enable_sessions()


@app.get("/agent/state")
def agent_state(request, session: Session):
    prior = session.get().get("visits", 0)
    session.update(visits=prior + 1)
    return {
        "session_id": session.id,
        "visits": prior + 1,
        "data": session.get(),
    }

Enabling Sessions

app.enable_sessions()

This activates the Rust-backed session store. Sessions are:

• Created on first use (new session ID generated)
• Persisted across requests via cookie or query param
• Available in any handler by declaring session: Session

System Routes

app.enable_system_routes()

Enables:

• GET /_system/tools — List registered MCP tools
• POST /_system/tools/call — Call an MCP tool

See Also

• Agent System Guide — Deep dive into agent-native features
• Dependency Injection API — Session in DI
• JustAPIApp — enable_sessions() and enable_system_routes()