Fardin Vahdat

Senior Frontend & Web3 Engineer · 8+ yrs building DApps · Frontend × Web3 × AI · Building in public

[x402trace @x402trace]

v0.3.2 of x402trace is live on npm — local CLI debugger for x402 payment flows on Base.

5 new metadata-propagation sub-checks, new `upstream_stuck` verdict, JSON API stability contract.

pnpm dlx [email protected]

https://t.co/qQqSHN4ZGE

#x402 #Base

[Fardin Vahdat @Fardin_Vahdat]

Shipped x402trace in 6 weeks by cutting four obvious-but-wrong
features: mainnet, multi-facilitator, auto-refund, ERC-6492.

The heuristic that fell out: a good scope cut is one you can describe
in one sentence and undo in one quarter.

https://t.co/FG3zupjOaB

[Fardin Vahdat @Fardin_Vahdat]

npm i x402trace

docs: https://t.co/ybTH6Ns75d
npm: https://t.co/BUWJ6pvvdX
live tx from the demo: https://t.co/H0zHPt9kQk

[Fardin Vahdat @Fardin_Vahdat]

four moves across the payment lifecycle:

• validate — pre-flight a wallet before signing
• proxy --reconcile — live capture + on-chain match
• inspect — offline replay of captured logs
• explain — plain-English diagnosis of failed 402s

[Fardin Vahdat @Fardin_Vahdat]

shipped x402trace v0.2.2

a local CLI debugger for x402 — the HTTP-402-based agentic-payment protocol on @base

catches the canonical "wallet debited but server thinks payment failed" bug from coinbase/x402#1062 in seconds, against real Base Sepolia.