API changelog

What this page is

Every change to the SIGNL API that a developer could notice is listed here, newest first, with the date it lands and, for a removal, the date it stops working.

Response contracts

The API has two response contracts, legacy and 2026-10-26. A credential is pinned to one of them, and a single request can try the other by sending the SIGNL-Version header. A value that is not one of the two is refused with the code unknown_version.

Every response carries X-Request-Id, SIGNL-Version and Cache-Control: private, no-store.

On 2026-10-26 an error is a typed body with a stable code, a status chosen from that code, a request id and a retry flag. A list that pages by cursor hands back a cursor that stops working after 24 hours.

Deprecations

No operation is deprecated yet.

When one is, it keeps working until its sunset date. Each of its responses carries a Deprecation header, a Sunset header and a link to this page. After the sunset date it answers 410 with the code operation_sunset.

Changes

28 Oct 2026

Added the 2026-10-26 response contract: typed errors, a request id on every response, and discovery fields on GET /api/v1/tools. No key is on it unless you send SIGNL-Version: 2026-10-26; every existing key stays on legacy and its responses do not change.