Codex Machine Payment Protocol (MPP)

Use this skill to access the Codex Supergraph without an API key via the MPP challenge flow.


HTTP endpoint	`https://graph.codex.io/graphql`
Opt-in header	`X-Codex-Payment: mpp`
Credential header	`Authorization: Payment <base64url-credential>`

How it works

Send a GraphQL query with X-Codex-Payment: mpp (no credential).
Server returns 402 Payment Required with WWW-Authenticate: Payment ... challenges.
Client solves one challenge and retries with Authorization: Payment <credential>.
Server returns GraphQL data + Payment-Receipt header.

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