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 installed version (agents 0.27.0), `Agent` extends Cloudflare's `DurableObject<Env>` directly. I confirmed this in the package's type declarations (`node_modules/agents/dist/agent-routing-Bhdbvf7s.d.ts:4521`). Before 0.22.0, `Agent` extended `Server` from `partyserver`, which in turn extended `DurableObject`. That PartyServer runtime is now bundled inside the package under `agents/lifecycle`, so `Agent` is still a Durable Object but no longer sits on top of a `partyserver` class.

Answering cost $0.12.

Grade

correct

The judge's reason: It states Agent extends DurableObject directly with PartyServer runtime bundled under agents/lifecycle, mentioning Server only as past behavior.

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-sync/agents-0-22-0-9-b.jsonl. Thinking and the session's settings are left out. The raw log

1. Tool call: Grep

   {
     "pattern": "class Agent\\b.*extends",
     "path": "C:\\Users\\haya0\\AppData\\Local\\Temp\\ludion-bench-nBQNMO\\work\\node_modules\\agents\\dist",
     "glob": "*.d.ts",
     "output_mode": "content"
   }

2. Tool output

   No matches found

3. Tool call: Grep

   {
     "pattern": "class Agent<",
     "path": "C:\\Users\\haya0\\AppData\\Local\\Temp\\ludion-bench-nBQNMO\\work\\node_modules\\agents",
     "output_mode": "content",
     "head_limit": 5
   }

4. Tool output

   node_modules\agents\dist\agent-routing-Bhdbvf7s.d.ts:4517:declare class Agent<
   node_modules\agents\dist\src-DgCbZtIR.js.map:1:[Omitted long matching line]

5. Tool call: Read

   {
     "file_path": "C:\\Users\\haya0\\AppData\\Local\\Temp\\ludion-bench-nBQNMO\\work\\node_modules\\agents\\dist\\agent-routing-Bhdbvf7s.d.ts",
     "offset": 4517,
     "limit": 8
   }

6. Tool output

   4517	declare class Agent<
   4518	  Env extends Cloudflare.Env = Cloudflare.Env,
   4519	  TState = unknown,
   4520	  Props extends object = object
   4521	> extends DurableObject<Env> {
   4522	  /**
   4523	   * Runtime lifecycle and reusable durable capabilities for this Agent.
   4524	   *

7. Agent

   In the installed version (agents 0.27.0), `Agent` extends Cloudflare's `DurableObject<Env>` directly. I confirmed this in the package's type declarations (`node_modules/agents/dist/agent-routing-Bhdbvf7s.d.ts:4521`). Before 0.22.0, `Agent` extended `Server` from `partyserver`, which in turn extended `DurableObject`. That PartyServer runtime is now bundled inside the package under `agents/lifecycle`, so `Agent` is still a Durable Object but no longer sits on top of a `partyserver` class.