Architecture

QNTX projects form a layered stack. Each layer builds on the one below, but every crate can be used independently.

How Projects Connect

Payment Flow (x402)

A typical pay-per-request flow involves three parties:

1. Client (x402-openai or r402 client) sends a request to a paid endpoint.
2. Server (r402 server middleware) responds with 402 Payment Required and a price tag.
3. Client signs a payment payload and retries the request.
4. Server forwards the payment to the Facilitator for on-chain settlement.
5. Facilitator verifies the signature and broadcasts the transaction.

Client ──── request ────▶ Server
Client ◀─── 402 + price ─ Server
Client ──── request + payment ──▶ Server ──── verify ──▶ Facilitator
Client ◀─── 200 + content ────── Server ◀─── ok ─────── Facilitator
                                  Server ──── settle ──▶ Facilitator

Agent Communication Flow (A2A)

Two agents communicate via the Agent2Agent protocol:

1. Caller agent discovers the remote agent via its Agent Card.
2. Caller sends a task message via JSON-RPC over HTTP.
3. Remote agent processes the task and streams results back via SSE.

Caller ──── GET /.well-known/agent.json ──▶ Remote Agent
Caller ◀─── Agent Card ───────────────────── Remote Agent
Caller ──── POST /a2a (send_message) ──────▶ Remote Agent
Caller ◀─── SSE stream (task updates) ────── Remote Agent

On-chain Identity (ERC-8004)

Agents register their identity on-chain and build reputation:

1. Register — mint an ERC-721 agent identity NFT with a metadata URI.
2. Discover — other agents query the registry to find agents by ID.
3. Validate — validators assess agent capabilities and record results.
4. Reputation — clients submit feedback; aggregated scores are publicly queryable.

Supported Chains

Family	Networks	Used by
EVM (EIP-155)	Ethereum, Base, Optimism, Arbitrum, Polygon, Avalanche, Celo, Monad + testnets	r402, Facilitator, ERC-8004, Kobe
Solana (SVM)	Mainnet, Devnet	r402, Facilitator, Kobe
Bitcoin	Mainnet, Testnet	Kobe