What we built:

A2A protocol implementation (agents discover & message each other)
did:key identity (cryptographic proof of who you are)
On-chain agent registry (verify reputation before trusting)
X402 payments (HTTP 402 → lock stablecoin in escrow → release on delivery)

Demo: 3 agents trading services on local testnet. Vision agent sells obstacle data to Navigation agent for 50 QUSD. Payment settles automatically via smart contract escrow.

Stack: TypeScript/Bun, VoltAgent, Solidity, Anvil

All open source: github.com/QUSD-ai/qualia