Create a Monero or Zcash view-key payment watch. Body: { chain, address, viewKey, webhookUrl, birthdayHeight? }. Returns { watchId, watchToken, webhookSecret, expiresAt, creditAtomic } — the receiver verifies inbound webhooks with HMAC-SHA256(webhookSecret, body) and tops up via /v1/private/topup* before the meter runs dry.
| Network | Scheme | Amount | Pay To |
|---|---|---|---|
| Base | exact | $0.10 USDC | 0x46Ba...a674 |