x-route-source
`x-route-source` appears on operations. Its value is a string. Used by a single provider across 1 OpenAPI document. Observed values include `app/api/v1/agents/[agentId]/mcp/route.ts`, `app/api/v1/agents/[agentId]/pins/route.ts`, `app/api/v1/chat-sessions/[sessionId]/route.ts`, `app/api/v1/workspaces/[workspaceId]/pins/route.ts`. Consistent with runtime & gateway — 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 | 153 |
What its value looks like
| Value shape | Occurrences |
|---|---|
| string | 153 |
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 runtime & gateway job.