Changelog

All notable changes to this project are documented here. The format is based on Keep a Changelog and this project adheres to Semantic Versioning.

[0.2.0] — Stateful runtime, sessions & persistence

The first release with the full layered runtime on top of the existing one-shot core. Nothing one-shot broke — the new layers are opt-in. See DESIGN.md for the architecture and ROADMAP.md for the phased plan.

Layer 1 — Stateful agent (ExAgent.Server)

• ExAgent.Server — a supervised, long-lived agent that preserves conversation history, accumulates usage, threads stateful models across runs, and emits events. API: chat/3, send_message/3 (async → event), stream/3, steer/2, abort/1, set_model/2, history/1, usage/1, health/1.
• ExAgent.AgentSupervisor — DynamicSupervisor to start/stop agents by id.
• Runs execute under ExAgent.TaskSupervisor, so a Server keeps answering abort/1, health/1 and backpressure (:busy / :queue_full) during long runs.
• reset/1 — clear the conversation history and accumulated usage (e.g. a chat UI's "clear" button); only when idle.

Layer 2 — Persistence (ExAgent.Store)

• ExAgent.Store behaviour + ExAgent.Store.ETS (dev/test default).
• ExAgent.Server.Snapshot — a strictly JSON-serializable checkpoint (history + usage + metadata). By construction it never carries pids, secrets or tool closures; the live model/tools come from an app-supplied template on restart.
• ExAgent.Server checkpoints after every run and rehydrates history/usage on restart (store: :ets). Survives supervised-agent crashes.

Layer 3 — Session & coordination (ExAgent.Session)

• ExAgent.Session — a coordinated, multi-participant interaction with shared state and turn-taking. Lifecycle start/join/leave/take_turn/pause/resume/close. The Session is the single writer of shared_state.
• ExAgent.Session.TurnPolicy behaviour + RoundRobin / Initiative impls (dispatch by struct, like ExAgent.Model).
• ExAgent.Session.Participant and ExAgent.Session.SharedState (a handle for RunContext.deps so tools read/propose through the Session).

Cross-cutting

• ExAgent.Event — versioned, serializable event envelope (the UI/runtime contract; distinct from :telemetry).
• ExAgent.PubSub behaviour + None / Local (Registry) / Phoenix (dynamic, no hard dependency) impls. Agents publish on "exagent:agent:<id>", sessions on "exagent:session:<id>".

Core additions (backward compatible)

• ExAgent.run/3 accepts :on_event (loop event sink, no-op by default), :prepend_instructions, and :run_id. The result map now also exposes :model (the possibly-updated model, so stateful models thread across runs).

Docs & examples

• DESIGN.md, ROADMAP.md. New examples: examples/stateful_agent.exs, examples/multi_agent_session.exs. ex_doc module groups by layer.
• 159 tests (was 96), stable across repeated runs.

[0.1.1]

• Fix structured-output JSON Schema generation for embeds_many / embeds_one.

[0.1.0]

• Initial release: agent loop, providers (OpenAI / Anthropic / Z.AI / OpenRouter / Test), deftool-derived tool schemas, Ecto structured output with retry, streaming, capabilities, UsageLimits, telemetry, message-history serialization.