agents-0-22-0-9-b

Question

What base class does Agent extend in the Cloudflare Agents SDK?

Answer key

A correct answer says

`Agent` extends Cloudflare's `DurableObject` directly, with the needed PartyServer runtime vendored into `agents/lifecycle`.

The stale answer

`Agent` extends PartyServer's `Server` class.

The change's lesson

Answer

In the Cloudflare Agents SDK (the `agents` package), `Agent` extends `Server` from the `partyserver` library. `Server` is in turn built on Cloudflare's `DurableObject` class. So every Agent is a Durable Object underneath. That is where it gets its persistent state, its embedded SQLite storage, WebSocket handling and scheduling.

I answered this from memory and didn't check the current source. The SDK changes quickly, so it's worth confirming in the latest `agents` package if you need it to be exact.

Answering cost $0.05.

Grade

wrong

The judge's reason: It states the stale fact that Agent extends PartyServer's Server class rather than extending DurableObject directly.

The judge's log

Session log

What the agent wrote, the tools it called, and what they returned, from docs/bench/2026-10-11-done3/runs/B-project/agents-0-22-0-9-b.jsonl. Thinking and the session's settings are left out. The raw log

1. Agent

   In the Cloudflare Agents SDK (the `agents` package), `Agent` extends `Server` from the `partyserver` library. `Server` is in turn built on Cloudflare's `DurableObject` class. So every Agent is a Durable Object underneath. That is where it gets its persistent state, its embedded SQLite storage, WebSocket handling and scheduling.
   
   I answered this from memory and didn't check the current source. The SDK changes quickly, so it's worth confirming in the latest `agents` package if you need it to be exact.