Durable Extension

What it demonstrates

The Durable Extension makes agents and multi-agent orchestrations durable: threads, orchestration progress, and workflow steps are checkpointed on Durable Task infrastructure. Sessions survive process crashes, resume on any worker, and can pause for hours or days (human-in-the-loop) without burning compute. You wrap normal agents in AgentFunctionApp(agents=[...]), which auto-generates HTTP endpoints (POST /api/agents/<Name>/run) and persists conversation state per x-ms-thread-id — no manual thread objects.

One real excerpt

from agent_framework.azure import AgentFunctionApp

app = AgentFunctionApp(agents=agents)  # registering makes each thread durable

@app.orchestration_trigger(context_name="context")
def triage_orchestration(context):          # a generator (def + yield), NOT async
    email_text = context.get_input()
    spam_agent = app.get_agent(context, "SpamDetector")   # the DURABLE wrapper
    session = spam_agent.create_session()
    detection = yield spam_agent.run(messages=f"...{email_text}", session=session,
                                     options={"response_format": SpamDetectionResult})

The gotcha

Inside an @app.orchestration_trigger you must NOT call the raw agent — fetch the durable wrapper with app.get_agent(context, "Name"), or the step won’t be checkpointed. The trigger is a generator (def + yield), not async def, because Durable Functions replays it after a failure and every yielded step must be a resumable point. Structured output goes through options={"response_format": MyModel} and comes back under .get("structured_response"). This can’t run under plain uv run: durable hosting needs the Azure Functions host (func start), Azurite, the Durable Task Scheduler emulator, and agent-framework-azurefunctions.

Azure / MAF mapping

Each registered agent is a plain Agent over FoundryChatClient (project_endpoint + model + AzureCliCredential) — identical whether or not it is later made durable. The lesson runs the same Foundry agent in plain (non-durable) mode as a smoke test, then shows the durable wiring for func start.

Run it

uv run tutorial/04-hosting/03_durable_extension.py — needs Foundry creds (az login). Worked if optional durable lines print, then a local smoke test classifies the spam email.

Next: Openai Endpoints