DELTA Witness API

One core service exposes Capture and Guard. Both accept JSON, issue an x402 v2 challenge, settle USDC on Base mainnet before Browser Run, and return proof metadata.

Guard request

{
  "url": "https://example.com/terms",
  "prior_proof_id": "optional UUID",
  "expected": {
    "contains": ["Refund window: 30 days"],
    "excludes": ["Final sale"]
  }
}

Use the returned safe, changed, reason, and diff fields as a deterministic gate. A proof reference is always returned for a completed paid observation.

Safety and privacy

Only public HTTP(S) targets on ports 80/443 are accepted. Local, private, link-local, metadata, credential-bearing, unsafe redirect, and private-DNS targets are rejected. Raw HTML, Markdown, and screenshots remain private; verifier routes publish metadata and hashes.

Recurring Watch

Watch is available through authenticated marketplace/reseller gateways as prepaid finite quota. Checks run no more often than every 15 minutes, pause when the prepaid unit price falls below DELTA's live cost floor, and can deliver HMAC-signed webhooks.

OpenAPI 3.1 · Agent skill · Postman collection · Distribution manifest