---
title: streamDevTools
description: Gateway RPC for DevTools snapshot and delta streams.
maturity: stable
apiVersion: v1
---

- Method: `streamDevTools`
- Scope: `observability:read`
- Transport: WebSocket RPC (streaming only)
- Request: `{ runId, afterSeq?, fromSeq? }`
- Response: `{ streamId, runId, fromSeq, afterSeq }`

Errors are versioned as `v1` and include `InvalidRequest`, `Unauthorized`, `Forbidden`, `RunNotFound`, `SeqOutOfRange`, `BackpressureDisconnect`, and `Internal`.

The legacy `fromSeq` field is accepted; `afterSeq` is the stable v1 name. If both are provided, they must match.
