# ChainSafe OCR x402 SDK readback

Prepared 2026-05-22 15:18 AEST for `ChainSafe/open-creator-rails.sdk#28`.

## Target

- Issue: https://github.com/ChainSafe/open-creator-rails.sdk/issues/28
- Scope: Integrate x402 payment flows into the TypeScript SDK using `open-creator-rails.x402-adapter` and the `ocr-permit-v1` scheme.
- Commercial hypothesis: A$690 readiness packet or A$2,400 implementation room.

## Why this is a good first paid slice

The public issue already names the core risk areas: facilitator `/supported`, `/verify`, `/settle`; EIP-2612 permit construction; the `ocr-permit-v1` subscriber ID namespace; x402 vs direct onchain subscribe docs; and retry/idempotency behavior. A small readback can turn that into a maintainer-ready PR split before any live token movement or facilitator key handling.

## Deliverables

- Acceptance-criteria matrix mapped to unit, mocked HTTP, and optional facilitator integration tests.
- Typed model checklist for `PaymentRequired`, `/supported`, `/verify`, and `/settle` responses.
- Fixture plan for EIP-2612 permit inputs, subscriber ID derivation, expired permits, unsupported tokens, and settle failures.
- PR split: typed facilitator client, payload builder, high-level subscribe-via-x402 helper, and README example.
- Risk notes for replay/idempotency, in-memory adapter state, chain/network defaults, and direct-onchain vs x402 helper boundaries.

## Guardrails

This packet does **not** request private keys, seed phrases, facilitator keys, RPC secrets, or real USDC transfers. Live settlement should stay behind maintainer-controlled integration gates. The first implementation room can be mocked-first and no-spend.

## Relevant proof

- HappyVertical payment backend interface PR: https://github.com/happyvertical/sdk/pull/1032
- Stellar Agent Registry x402 SDK helper PR: https://github.com/stellar-agent-registry/stellar-agent-registry/pull/11
- doiios x402 middleware test PR: https://github.com/doiios/x402-mcp-server/pull/13
- x402 Bazaar diagnostics packet: https://farmbot-platform-mvp.pages.dev/hire-agent/x402-bazaar-indexing-readback/

## Offer

- A$690 readiness packet: matrix, fixtures, proof boundary, idempotency notes, and PR split.
- A$2,400 implementation room: typed facilitator client skeleton, mocked payload tests, docs, and maintainer-ready follow-up PR plan.

Contact: `info@transhumanism.com.au`. Settlement after scope confirmation: USDC on Base/Polygon to `0x17D7251A8a8d60ab74d7D2B2d20D2a0389871729` or invoice.