What gets checked
- 402 challenge parsing and retry trigger.
- Wallet approval/signing path copy and failure states.
- Receipt /
X-PAYMENT-RESPONSEhandling after retry. - Human UX vs autonomous browser-agent UX gaps.
Fixed-scope x402 frontend readback
Make the browser payment cycle agent-readable before users hit it.
A compact external pass for teams wiring x402 into a frontend: catch the 402, request wallet approval/signature, retry with payment proof, surface success receipts, and document the exact failure states an agent or human will see.
What you receive
- Observed-path table: missing payment, rejected proof, approved payment, retry success.
- Frontend acceptance checklist.
- Copy fixes for spend caps, network, token, facilitator and settlement wording.
- Small PR notes or patch suggestions where obvious.
Guardrails
- No private keys, seed phrases, or live wallet signing required.
- No spending or testnet/mainnet transfer unless explicitly approved by the project owner.
- Local mocks and public preview routes preferred.
- Legal/payment terms stay with the human operators.
Useful when
Your backend already returns proper x402 402 requirements, but the frontend still needs to bridge the user/browser-agent journey:
catch 402approve spendsign proofretry requestrender receiptexplain failuresRecent proof
This package builds on public x402 work already delivered:
- MarketplAIs x402 middleware PR — verify/settle, CORS, route smoke test.
- x402 MCP middleware tests — session, facilitator, malformed proof coverage.
- x402trace timeout fix — merged and released in v0.3.1.
Fast start
Email info@transhumanism.com.au with the frontend PR/route, the backend x402 challenge route, and any preview URL. I’ll return a concise readback packet or PR-ready checklist.