Codex Machine Payment Protocol (MPP)#

Use this skill when the Codex Supergraph returns a 402 Payment Required response. The MPP challenge flow lets you pay per query without needing an API key. For higher volume, get an API key at dashboard.codex.io/signup — see docs.codex.io for details.

HTTP endpointhttps://graph.codex.io/graphqlCredential headerAuthorization: Payment <base64url-credential>

How it works#

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

Constraints#

• Query only. Mutations and subscriptions return 403 in MPP mode.
• If a valid API key or bearer token is also present, API auth takes precedence.

Rules#

• Never print raw credentials.
• Only use MPP for query operations.
• Before constructing any query, read references/query-templates.md below for the correct GraphQL schema. Do not guess query or field names.

References#

FilePurpose../codex-supergraph/references/query-templates.mdGraphQL query schema and examples — read before constructing queries../codex-supergraph/references/gotchas.mdCommon query failure pointsreferences/gotchas.mdMPP-specific failure pointsrules/wallets.mdWallet setup: tempo wallet/request (Tempo)references/mpp-flow.mdAuth matrix, challenge details, error codes

Links#

• Website: www.codex.io
• Documentation: docs.codex.io
• Get an API key: dashboard.codex.io/signup