1. Subscriber namespace
Pin the keccak256(abi.encode("ocr-permit-v1", userAddress)) identity path and test it separately from the SDK's default subscriberToId.
ChainSafe open-creator-rails.sdk #28 · ocr-permit-v1 / x402
A safe implementation map for first-class OCR x402 subscription helpers.
This packet is tailored to open-creator-rails.sdk#28. It turns the broad integration ask into a maintainer-ready acceptance matrix before anyone wires real facilitator keys, hot-wallet authority, or live settlement paths.
2. Payload + permit seam
Define the exact typed fields parsed from a 402 PaymentRequired response, the EIP-2612 signing inputs, and which values must be rejected locally.
3. Verify/settle lifecycle
Separate /supported, /verify, and /settle clients from the high-level subscribe helper so retry/idempotency failures are observable.
Why this is the low-risk first paid slice
Issue #28 already identifies the right reference docs: architecture, ocr-permit-v1, integration guide, and security notes. The gap is not another vague "add x402" task; it is a concrete contract between the SDK, the adapter facilitator, and the subscription identity namespace.
This packet deliberately avoids live token movement. It does not request private keys, seed phrases, facilitator keys, RPC secrets, or a real USDC transfer. Live settlement should stay behind maintainer-controlled integration gates and mocks should carry the first PR.
Deliverables
- Acceptance-criteria matrix mapped to unit, mocked HTTP, and optional facilitator integration tests.
- Typed model checklist for
PaymentRequired,/supported,/verify, and/settleresponses. - 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.
Relevant proof
HappyVertical payments interface
Payment backend skeleton, conformance helper, and review-fix follow-up. x402 SDK helper PR
Payment helper, typed errors, tests, typecheck and build through a workspace. x402 middleware tests
Verify/settle failure paths and header behavior covered by targeted tests. x402 diagnostics packet
Existing discovery/facilitator readback format for payment route launch checks.
Payment backend skeleton, conformance helper, and review-fix follow-up. x402 SDK helper PR
Payment helper, typed errors, tests, typecheck and build through a workspace. x402 middleware tests
Verify/settle failure paths and header behavior covered by targeted tests. x402 diagnostics packet
Existing discovery/facilitator readback format for payment route launch checks.