x-source-documentation
`x-source-documentation` appears on operations. Its value is a string. Used by 3 providers across 3 OpenAPI documents. Observed values include `https://dev.3vjia.com/document?apiId=646398030987284576`, `https://dev.3vjia.com/document?apiId=456509490821398562`, `https://dev.3vjia.com/document?apiId=832299125029617719`, `https://dev.3vjia.com/document?apiId=713058818141077606`. Consistent with documentation & dx — this is inferred from where the key appears and what it carries, not from any published definition.
Where it appears
| Location in the document | Occurrences | |
|---|---|---|
| operation | 429 | |
| info | 2 |
What its value looks like
| Value shape | Occurrences |
|---|---|
| string | 431 |
Observed values
Sampled from the specifications, most frequent first.
Providers publishing it
All 3.
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.