Buy a prepaid balance in a single x402 settlement and get a secret credit token. Send it as the `x-credit-token` header on any paid service and each call debits its price from your balance — no per-call signature, no settlement latency. Built for agents that fire many checks a minute. Tiers: $0.25 (starter), $1, $5 (+10%), $20 (+20%). The token is shown once; balance lasts 180 days.