Verifiable API Billing

Don't trust the logs. Verify the charge. Issue machine-checkable receipts for API / agent usage.

What the demo proves

1. Attest — bind usage to a signed attestation
2. Billing fingerprint — commit meter + tariff fields
3. Meter signature — Ed25519 meter envelope
4. Tariff digest — versioned tariff snapshot
5. Replay guard — reject reused event IDs in-window
6. Receipt — portable evidence (QZR-1 levels)
7. Verify — offline or API verify; tamper fails closed

Interactive controls load in the app below. Docs: pilot runbook · QZR-1 · Break the proof.