instrumentDurableObjectWithSentry breaks @callable() RPC methods from Cloudflare Agents SDK

[alexander-zuev]

Environment

• @sentry/cloudflare: 10.46.0
• agents: 0.9.0 (Cloudflare Agents SDK)
• wrangler: 4.78.0

Description

instrumentDurableObjectWithSentry() wraps a Durable Object class in a way that breaks @callable() decorator metadata from the Cloudflare Agents SDK. The Agents SDK's RPC dispatcher cannot find callable methods on the wrapped class, returning "Method <name> is not callable" for any @callable() decorated method.

All @callable() methods on the class stop working after wrapping — this is not specific to any single method.

Relevant docs

• @callable() decorator — Cloudflare Agents SDK — mechanism for exposing RPC methods on Durable Objects via WebSocket
• instrumentDurableObjectWithSentry — Sentry docs — Sentry's DO wrapper

Reproduction

import { callable } from 'agents'
import { AIChatAgent } from '@cloudflare/ai-chat'
import * as Sentry from '@sentry/cloudflare'

class MyAgentBase extends AIChatAgent<Env, State> {
 @callable()
 async setMode(mode: string) { /* ... */ }

 @callable()
 async stopStream() { /* ... */ }
}

// ✅ Without wrapper — all @callable() methods work via RPC
export const MyAgent = MyAgentBase

// ❌ With wrapper — all @callable() methods return "not callable"
export const MyAgent = Sentry.instrumentDurableObjectWithSentry(
 (env) => ({ dsn: '...' }),
 MyAgentBase,
)

Client-side (using Agents SDK useAgent):

Error: Method setMode is not callable

Expected

instrumentDurableObjectWithSentry should preserve @callable() metadata so the Agents SDK RPC dispatcher can discover decorated methods on the wrapped class.

Notes

• Standard DurableObject subclasses (non-Agents SDK) work fine with the wrapper
• The issue is specifically with the Agents SDK's @callable() decorator which uses TC39 standard decorators (not TypeScript legacy decorators) to register methods for WebSocket RPC discovery
• The wrapper likely needs to forward decorator metadata or prototype chain from the original class

[linear-code]

JS-2044

[timfish]

Thanks for reporting. We'll take a look!

[JPeer264]

@alexander-zuev I was just trying to reproduce your issue and had troubles to make it break like you described (locally and deployed). Could you check if this is close to your setup: https://github.com/JPeer264/sentry-repros/tree/issue-20099

Maybe you can even try to reproduce it based on the given link and guide me how you set it up

I actually discovered a bug with this setup: when having enableRpcTracePropagation set, then it is indeed not working anymore, but it fails with a different error.

(edit: I opened a PR that tests this use case, and it should work as described above)