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MPP (Machine Payment Protocol) Payments

Conto supports the Machine Payment Protocol (MPP) for session-based micropayments on the Tempo blockchain. MPP enables agents to open payment sessions, make incremental charges, and settle when done.

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How It Works

Agent opens session  →  Makes requests (charges accrue)  →  Session closes  →  Settlement
  1. Agent calls an MPP-enabled service and receives a 402 challenge
  2. Agent pre-authorizes the session deposit through Conto policies
  3. Agent opens an MPP session with a deposit budget
  4. Agent makes requests, each consuming part of the deposit
  5. Session closes and unused deposit is returned

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Pre-Authorization

Before opening an MPP session, validate against policies and budget limits: 
curl -X POST https://conto.finance/api/sdk/mpp/pre-authorize \
  -H "Authorization: Bearer $CONTO_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "amount": 10.00,
    "recipientAddress": "0xServiceAddress",
    "resourceUrl": "https://api.service.com/stream",
    "intent": "session",
    "depositAmount": 10.00
  }'
Conto derives serviceDomain from resourceUrl, so you do not need to send it separately. Response (Approved): 
{
  "authorized": true,
  "wallet": {
    "id": "cmm5b0wal000l49h7ckrtb11p",
    "address": "0xAgentWallet",
    "chainId": "42431",
    "availableBalance": 500.0
  },
  "reasons": ["Within MPP session budget", "Service domain allowed"]
}
Response (Denied): 
{
  "authorized": false,
  "error": "MPP pre-authorization denied",
  "code": "BUDGET_EXCEEDED",
  "reasons": ["MPP session deposit $10 exceeds maximum $5"],
  "violations": [
    {
      "type": "MPP_MAX_SESSION_DEPOSIT",
      "limit": 5.00,
      "current": 10.00,
      "message": "Session deposit exceeds MPP budget"
    }
  ]
}

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Recording Transactions

After MPP charges are settled, record them in Conto: 
curl -X POST https://conto.finance/api/sdk/mpp/record \
  -H "Authorization: Bearer $CONTO_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "amount": 3.50,
    "recipientAddress": "0xServiceAddress",
    "txHash": "0xabc123...",
    "resourceUrl": "https://api.service.com/stream",
    "sessionId": "mpp_session_xyz",
    "scheme": "mpp",
    "walletId": "cmm5b0wal000l49h7ckrtb11p",
    "chainId": "42431"
  }'
Use the flat top-level settlement fields for the aggregate payment. For multiple per-call charges, send those details in batchItems; the record endpoint does not accept a top-level payments array. If you settle multiple calls together, keep the top-level fields for the aggregate settlement and send per-call detail records in batchItems: 
curl -X POST https://conto.finance/api/sdk/mpp/record \
  -H "Authorization: Bearer $CONTO_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "amount": 3.50,
    "recipientAddress": "0xServiceAddress",
    "txHash": "0xsettlement123...",
    "resourceUrl": "https://api.service.com/stream",
    "sessionId": "mpp_session_xyz",
    "batchItems": [
      { "amount": 1.00, "resourceUrl": "https://api.service.com/stream?chunk=1", "credentialId": "cred_1" },
      { "amount": 2.50, "resourceUrl": "https://api.service.com/stream?chunk=2", "credentialId": "cred_2" }
    ]
  }'

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Querying Services

View MPP services your agent has used: 
GET /api/sdk/mpp/services

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Budget Tracking

Check remaining MPP budget: 
GET /api/sdk/mpp/budget
Pass ?sessionId=... to inspect budget consumption for a specific MPP session. Session spend is counted from recorded MPP transactions with the same sessionId, not from unrelated wallet payments. If an agent has an active approved budget request, /pre-authorize returns a budgetRequest snapshot and /record decrements the remaining budget automatically.

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Unified Machine Spend View

If this agent also uses x402 or multiple paid services, use the shared machine-spend endpoints for a combined view: 
GET /api/sdk/service-spend/summary?protocol=mpp
GET /api/sdk/service-spend/services?protocol=mpp
See Machine Spend for the combined x402 + MPP analytics view.

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MPP Policy Rules

Configure MPP-specific policies to control session-based payments. The complete list of MPP rule types, value formats, and operators lives in Advanced Policies > MPP Protocol Rules.

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Supported Chain

MPP payments are supported on the Tempo blockchain, on both testnet and mainnet. The examples in this guide use Tempo Testnet.
PropertyTempo TestnetTempo Mainnet
Chain ID424314217
CurrencypathUSDUSDC.e
Explorerhttps://explore.moderato.tempo.xyzhttps://explore.tempo.xyz

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Next Steps

x402 Payments

HTTP 402 micropayments for APIs

Machine Spend

View unified x402 and MPP service spend

Advanced Policies

Configure MPP-specific policy rules