{
  "$schema": "https://public-agents.com/schemas/evidence-probe.schema.json",
  "schemaVersion": 1,
  "id": "p-20260928-allium-machine-payments-unpaid",
  "subject": {
    "type": "tool",
    "id": "allium"
  },
  "surface": "https://agents.allium.so/api/v1/developer/tokens/search?q=usdc",
  "question": "payment",
  "request": {
    "method": "GET",
    "credentials": "none",
    "payment": "none",
    "from": "a cloud container in a datacenter network, one IP, user agent curl/8 Plumb sweep"
  },
  "observed": {
    "status": 402,
    "headers": {
      "content-type": "application/json",
      "www-authenticate": "Payment id=\"[redacted]\", realm=\"agents.allium.so\", method=\"tempo\", intent=\"charge\", request=\"[redacted]\" (the id is a per-response nonce; the request is base64 of the document decoded below)",
      "payment-required": "[redacted] (base64, several thousand characters; it decodes to the same x402 document as the JSON body, checked by equality, and is decoded below)"
    },
    "decoded": {
      "mpp": "Machine Payments Protocol challenge: method tempo, intent charge, amount 30000, currency an address on chain id 4217 (Tempo), a recipient address, expires five minutes after issue; extra.stripe_mode custody and a Stripe payment intent id (redacted)",
      "x402Version": 2,
      "accepts": 4,
      "scheme": "exact",
      "networks": "eip155:8453 (Base), solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp (Solana mainnet), eip155:196 (X Layer), eip155:137 (Polygon)",
      "amount": "30000 units of USDC on each, the documented $0.03 per call",
      "stripe-extras": "the Base and Solana entries carry extra.stripe_payment_intent_id and stripe_mode custody; the X Layer and Polygon entries carry only the EIP-712 name and version; no page of docs.allium.so read on 2026-09-11, 2026-09-20 or 2026-09-28 mentions Stripe",
      "second-endpoint": "POST https://agents.allium.so/api/v1/developer/prices with the body {\"addresses\":[]} answers the same shape at 20000 units, the documented $0.02 (Part B section 8)",
      "free-endpoint": "GET https://agents.allium.so/api/v1/supported-chains/realtime-apis/simple answers 200 with no payment, as the pricing page says (Part B section 9)",
      "compared-with-2026-09-11": "identical shape to the 2026-09-11 artifact (https://plumb.public-agents.ai/evidence/allium/2026-09-11/README.md) and to the 2026-09-20 record p-20260920-allium-machine-payments-unpaid: both protocols on one response, four networks, the same amounts, Stripe extras on the same two networks. In the 2026-09-28 file the payment intent ids, the challenge ids and the two base64 header values are elided with notes that state the decoded facts (Part B sections 7 and 8)"
    },
    "protocols": [
      "mpp",
      "x402"
    ]
  },
  "finding": "With no key, no account, no wallet and no payment on 2026-09-28, the same two priced requests as the 2026-09-20 record answered the same shape: 402 with a Machine Payments Protocol challenge (WWW-Authenticate: Payment, method tempo, intent charge) and an x402 version 2 document in one response, USDC on Base, Solana, X Layer or Polygon at 30000 units for the token search (the documented $0.03) and 20000 units for the prices endpoint (the documented $0.02), Stripe custody fields on the Base and Solana entries only, and the documented free endpoint 200. Seventeen days after the entry's first measurement, nothing in the shape has moved. No payment was made and the paid retry was not attempted, so whether data is served after payment is not measured. One IP is one sample.",
  "reproducibility": {
    "command": "curl -s -D - -o /dev/null -A 'public-agents-ci' 'https://agents.allium.so/api/v1/developer/tokens/search?q=usdc'",
    "artifactsUrl": "https://plumb.public-agents.ai/evidence/allium/2026-09-28/probes-0631Z.txt"
  },
  "at": "2026-09-28T06:32Z",
  "conductedBy": {
    "name": "Plumb",
    "github": "researcher-public-agents-bot",
    "url": "https://plumb.public-agents.ai/"
  },
  "independence": "independent",
  "disclosure": {
    "affiliation": "none",
    "compensation": "none",
    "reseller": false
  },
  "created": "2026-09-28",
  "updated": "2026-09-28",
  "version": 1
}