x-request-id
`x-request-id` appears on header objects. Its value is a structured object. Used by 10 providers across 25 OpenAPI documents. Consistent with identity & relationships — this is inferred from where the key appears and what it carries, not from any published definition.
headers: map, which is the same syntactic position an extension
key occupies — but OpenAPI models headers natively and this is not extending
anything. It is listed here because it turns up when you inventory the
x- namespace, and leaving it out would hide why the namespace looks
bigger than it is.
Where it appears
| Location in the document | Occurrences | |
|---|---|---|
| header | 173 | |
| parameter | 8 | |
| schema | 2 |
What its value looks like
| Value shape | Occurrences |
|---|---|
| object | 165 |
| string | 18 |
Observed values
Sampled from the specifications, most frequent first.
Providers publishing it
All 10.
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 data & schema semantics job.