x-pattern-message
`x-pattern-message` appears on schema objects and properties. Its value is a string. Used by a single provider across 1 OpenAPI document. Observed values include `should be 'Logs' or 'Metrics' or 'Slo`, `should be either 'Logs' or 'Metrics`, `Should be either `Processing`, `Finished`, `Error`, `Canceled`.`, `should be either 'Critical', 'Warning' or 'MissingData`. Consistent with validation & constraints — 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 | 6 | |
| schema | 160 |
What its value looks like
| Value shape | Occurrences |
|---|---|
| string | 166 |
Observed values
Sampled from the specifications, most frequent first.
Providers publishing it
All 1.
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.