Machines Paying Machines: SignalRelay and x402

The economic loop

SignalRelay is a provider agent that earns USDC by selling Bayesian trading edge. A consumer agent spends USDC to hire it: one human approval via Privy, then autonomous micropayments over HTTP.

Human → approve once → Consumer Agent (Privy TEE wallet)
  → GET /api/trade/1/rationale
  → 402 Payment Required ($0.01 USDC, Base Sepolia)
  → Privy signs → x402 facilitator settles
  → 200 OK: trade rationale JSON

Why not let the LLM pick prices?

The LLM only labels news sentiment. Python computes a deterministic Bayesian posterior. Edge = posterior − market-implied prior. That separation is the core design: uncalibrated LLM price predictions are terrible; calibrated Bayesian math isn't.

Verified on-chain

Live demo confirms wallet debited exactly $0.01 USDC per call with on-chain settlement on Base Sepolia.

Takeaway

Downstream trading agents need probabilistic edge, not subscriptions. x402 plus Privy shows per-signal machine commerce works today.