Documentation & DX

x-category

`x-category` appears in the info block and on schema objects and properties. Its value is a string. Used by 4 providers across 30 OpenAPI documents. Observed values include `call`, `domain`, `response`, `session`. Consistent with documentation & dx — this is inferred from where the key appears and what it carries, not from any published definition.

Documentation & DX derived description
How this description was produced. It is assembled from what was measured in the corpus — where this key appears in a document, what shape its value takes, the values observed, and how many providers use it. It is not taken from a published definition, because for most extensions none exists. Read it as evidence, not as a specification. If you own this extension and want it described properly, tell us.
53 occurrences
30 documents
4 providers
purpose-named

Where it appears

Location in the documentOccurrences
operation 6
info 27
schema 20

What its value looks like

Value shapeOccurrences
string53

Observed values

Sampled from the specifications, most frequent first.

calldomainresponsesessionwebhooksasn lookupvalidationcors headers

Providers publishing it

All 4.

back-marketdoneontopx402sinch

Why this is not in OpenAPI

Extensions exist because a provider needed something the specification would not carry. Most of what they hold is not the API contract at all — it is operational metadata about the contract: documentation, lifecycle, policy, provenance, and now agents. That metadata is usually better placed alongside the contract, in an Overlay or an APIs.json index, than crammed inside it. See everything else doing the documentation & dx job.