molecule-core/sdk/python/molecule_agent/README.md

molecule_agent — Remote-agent SDK for Molecule AI

Build a Python agent that runs outside a Molecule AI platform's Docker network and registers as a first-class workspace. The agent gets bearer-token auth, pulls its secrets, calls siblings, installs plugins from the platform's registry, and reacts to platform-initiated lifecycle events (pause, delete) — all over plain HTTP.

This is the client side of Phase 30. The platform side ships in the same release; this package is just the SDK an agent author imports.

Install

pip install molecule-sdk     # ships molecule_plugin + molecule_agent

60-second example

from molecule_agent import RemoteAgentClient

client = RemoteAgentClient(
    workspace_id="<the-uuid-of-an-external-workspace-on-the-platform>",
    platform_url="https://your-platform.example.com",
    agent_card={"name": "my-remote-agent", "skills": []},
)

# 1. Register and mint a bearer token (cached at ~/.molecule/<id>/.auth_token).
client.register()

# 2. Pull secrets the platform was set to inject.
secrets = client.pull_secrets()
# → {"OPENAI_API_KEY": "...", ...}

# 3. (Optional) install a plugin locally — pulls a tarball, unpacks, runs setup.sh.
client.install_plugin("molecule-dev")
client.install_plugin("my-plugin", source="github://acme/my-plugin")

# 4. Run the heartbeat + state-poll loop until the platform pauses/deletes us.
terminal = client.run_heartbeat_loop()
print(f"loop exited: {terminal}")

A runnable demo with full setup walkthrough lives at sdk/python/examples/remote-agent/.

What the SDK gives you

Method	Phase	What it does
register()	30.1	Mint + cache the workspace's bearer token
pull_secrets()	30.2	Token-gated GET of merged secrets dict
install_plugin(name, source=None)	30.3	Stream plugin tarball, atomic extract, run setup.sh
poll_state()	30.4	Lightweight {status, paused, deleted} poll
heartbeat(...)	30.1	Single bearer-authed heartbeat
get_peers() / discover_peer()	30.6	Sibling URL discovery with TTL cache
call_peer(target, message)	30.6	Direct A2A with proxy fallback
run_heartbeat_loop()	combo	Drives heartbeat + state-poll on a timer; exits on pause/delete

What it doesn't do (yet)

• No inbound A2A server. Other agents can't initiate calls to your remote agent unless you host an HTTP endpoint yourself. Future start_a2a_server() helper will close this gap.
• No automatic reconnect after token loss. If ~/.molecule/<id>/.auth_token is deleted, you'll need to re-issue the token via the platform admin (since POST /registry/register is idempotent — it won't mint a second token for a workspace that already has one).

Design choices

• Blocking (requests), not async. Drops into any runtime — script, thread, asyncio loop. No framework lock-in.
• Token cached on disk with 0600 so a restart of the agent doesn't re-issue (the platform refuses anyway). Lives at ~/.molecule/<workspace_id>/.auth_token.
• URL cache for siblings is process-memory only, 5-minute TTL. Cleared on graceful failures via invalidate_peer_url.
• Tar extraction uses _safe_extract_tar that rejects path-traversal and skips symlinks — defense against tar-slip CVEs in case a plugin source is compromised.

Compatibility

Requires a Molecule AI platform with Phase 30 endpoints (PR #122 onwards). Older platforms grandfather pre-token workspaces through, so this SDK also works against a transition-period deployment — but you won't get the security benefits of bearer auth until both sides upgrade.

Related

• molecule_plugin — the other SDK in this package, for plugin authors. Different audience.
• sdk/python/examples/remote-agent/run.py — the runnable demo that proves all of the above end-to-end.