API versions and request ids
Two headers for running an integration in production: one that says which version of the API you are on, and one that lets support find your request.
What changed
Layout-Versionis a date. The current and only version is2026-10-01, and a request without the header gets it. Every answer from an endpoint says which version answered. A version the API does not answer is400 unsupported_version.X-Request-Idis on every answer from an endpoint, errors included. Quote it when you write to developer@layout.link.- A versioning policy. A breaking change ships as a new dated version, is marked breaking here, and the old version keeps working for at least 180 days.
Why it matters
Pin a version and a breaking change never reaches you until you choose it.
What to do
Send Layout-Version: 2026-10-01 in production, and log X-Request-Id beside your own request logs. See Versioning.
Breaking changes
None. Both headers are new, and a request without Layout-Version behaves as before.