agent-payments

Original：🇺🇸 English

Translated

Machine Payment Protocol (MPP) for keyless, pay-per-query access to the Codex Supergraph GraphQL API. Use when the user has no API key and wants to pay per query via the 402 challenge flow at https://graph.codex.io/graphql.

1installs

Sourcecodex-data/skills

Added on2026-03-14

NPX Install

npx skill4agent add codex-data/skills agent-payments

SKILL.md Content

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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.

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.
Do not reference legacy dashboard onboarding/top-up/balance payment endpoints.

Challenge flow

First request (no credential yet):

bash

curl -i -sS https://graph.codex.io/graphql \
  -H "Content-Type: application/json" \
  -H "X-Codex-Payment: mpp" \
  --data-binary '{"query":"query GetNetworks { getNetworks { id name } }"}'

Expected:

402 Payment Required

with multiple

WWW-Authenticate: Payment ...

challenges.

Retry with solved credential:

bash

curl -i -sS https://graph.codex.io/graphql \
  -H "Content-Type: application/json" \
  -H "X-Codex-Payment: mpp" \
  -H "Authorization: Payment <base64url-credential>" \
  --data-binary '{"query":"query GetNetworks { getNetworks { id name } }"}'

Expected: GraphQL data +

Payment-Receipt

header.

Rules

Never print raw credentials.
Only use MPP for
```
query
```
operations.
For available GraphQL operations and endpoint selection heuristics, see the
```
codex-supergraph
```
skill.

References

File	Purpose
references/mpp-flow.md	Auth matrix, challenge details, error codes
references/mpp-templates.md	MPP curl templates
references/wallets.md	Wallet setup: tempo wallet/request (Tempo) and awal (Base)