Managed Agents Deployment

Deploying a Managed Agents project

A nuvel-scaffolded Managed Agents project has a clean deploy story: the agent runs on Anthropic's infrastructure, your service is a thin proxy. That changes what you have to think about. This skill covers the parts that aren't obvious.

What lives where

You ship a thin FastAPI app. The heavy lifting is elsewhere.

Required env vars

The nuvel scaffold's setup.py writes the last three to .env after applying the YAMLs. For deployment, copy them from your local .env to the platform's environment configuration (Railway/Fly/Vercel/etc.) — they're stable across runs unless you re-run setup.py.

Agent-version pinning in production

MANAGED_AGENT_VERSION is the current head version after the last setup.py run. Two operational patterns:

Track latest (default). sessions.create(agent=AGENT_ID, ...) uses the current head. New sessions automatically pick up setup.py changes. Good for fast iteration; risky for traffic that needs reproducibility.

Pin explicitly. sessions.create(agent={"type": "agent", "id": AGENT_ID, "version": int(VERSION)}, ...). New sessions stay on a known version even if someone runs setup.py mid-flight. Good for prod; lets you roll forward in CI by re-running setup.py and bumping MANAGED_AGENT_VERSION.

The nuvel scaffold's orchestrator.py defaults to tracking latest. To pin, change the agent= argument to the dict form and read MANAGED_AGENT_VERSION from env.

The request/response contract

The default scaffold:

POST /run_sse/
Authorization: Bearer <API_KEY>     (if API_KEY env is set)
Content-Type: application/json
{ "prompt": "..." }

Response: text/event-stream
data: {"type": "session.created", "session_id": "sesn_..."}
data: {"type": "agent.message", "content": [...]}
data: {"type": "agent.tool_use", "name": "read", ...}
data: {"type": "session.status_idle", "stop_reason": {"type": "end_turn"}}
data: [DONE]

Frontends store the session_id from the first event so they can correlate later API calls (events.list for audit, files.list for outputs).

One session per request

Don't reuse a single session across HTTP requests for different users — each session is a separate conversation thread. Create a fresh session per request:

@app.post("/run_sse/")
async def run_sse(body: dict):
    return StreamingResponse(_sse_stream(body["prompt"]))

async def _sse_stream(prompt: str):
    # Inside the generator: create + stream + tear down per request.
    ...

If you want multi-turn for one user (e.g. chat), pass the previous session_id in subsequent requests and reuse it via events.send + events.stream against the same session. The session's history is preserved server-side; you don't have to send it back.

Bearer auth

The scaffold's pattern: if API_KEY env is set, require Authorization: Bearer <API_KEY> on /run_sse/. If unset, no auth (good for local dev). Don't reach for OAuth/JWT until there's a real reason — most internal-tool agents are fine with one shared bearer behind a VPN or Cloudflare Access.

For multi-tenant deploys, put auth in front of the FastAPI app (Cloudflare Access, an API gateway) — not inside it. The agent server should be a dumb relay.

Cost tracking

Per-turn cost lands on span.model_request_end events:

if event.type == "span.model_request_end":
    usage = event.model_usage  # {input_tokens, output_tokens, cache_creation_input_tokens, cache_read_input_tokens}
    persist_usage(session.id, usage)

Per-session aggregate is on client.beta.sessions.retrieve(session.id).usage after the session ends. For multi-tenant cost attribution, persist per-event usage to a database keyed by session.id and your tenant ID.

The MAX_BUDGET_USD Claude Agent SDK pattern doesn't apply here — Managed Agents don't expose a hard per-session budget. If you need a cap, enforce it at your application layer: subscribe to span.model_request_end, sum cost, and client.beta.sessions.events.send an interrupt if you exceed your threshold.

Reconnecting under load

A long-lived agent process (cron job, websocket bridge) will eventually drop a stream. Always implement the consolidation pattern from managed-agents-events — fetch history on (re)connect, dedupe by event ID, then resume the live stream.

The nuvel scaffold's server.py doesn't implement reconnection because the FastAPI request lifecycle is short-lived (one request, one stream). If you're building a long-running consumer, add the pattern.

Docker + Railway + Fly

The scaffold ships a Dockerfile (python:3.12-slim, copies the project, runs python server.py) and railway.json (Dockerfile builder, /health healthcheck). Portable to Fly or Cloud Run with a fly.toml or service yaml.

Env var hygiene at build time. Don't bake ANTHROPIC_API_KEY, MANAGED_AGENT_ID, etc. into the Docker image — set them at the platform level. The image stays generic; the env varies per deploy.

Health check. /health returns 200 with the agent name. Wire it to your platform's healthcheck (healthcheckPath: /health in railway.json already does this).

Cold starts. The Anthropic client doesn't pre-warm. First request after a cold start has ~100-200ms extra latency. Acceptable for most use cases; if it isn't, keep one container warm via a low-frequency cron pinging /health.

Updating the agent without downtime

Edit agent.yaml, run setup.py — this updates the agent in place (creates a new version) and bumps MANAGED_AGENT_VERSION in .env. Existing sessions running on older versions continue undisturbed. New sessions pick up the new version (default behavior, since the scaffold tracks latest).

For pinned production, the rollout is two steps:

1. Re-run setup.py against your prod environment (creates new version N+1, but pinned sessions still use N).
2. Update MANAGED_AGENT_VERSION in your platform's env config and restart. New sessions now use N+1.

If N+1 regresses, set the env var back to N and restart — instant rollback.

Pre-launch checklist

• ANTHROPIC_API_KEY, MANAGED_AGENT_ID, MANAGED_AGENT_ENV_ID set in platform env
• API_KEY set if /run_sse/ is internet-facing
• /health healthcheck wired to the platform
• Reconnect/consolidation pattern in any long-running consumer (not the FastAPI scaffold by default)
• Decide: latest-tracking or pinned versions for production traffic
• If multi-tenant: auth in front of the app, per-request session creation
• If cost-sensitive: span.model_request_end persistence + per-session budget enforcement