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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": "wal_123",
    "address": "0xAgentWallet",
    "chainId": "4217",
    "availableBalance": 500.0
  },
  "reasons": ["Within MPP session budget", "Service domain allowed"]
}

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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": "wal_123",
    "chainId": "4217"
  }'
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. 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. See Advanced Policies for the full rule type reference. Key rule types:
  • MPP_MAX_PER_REQUEST — Cap per individual charge
  • MPP_PRICE_CEILING — Hard price ceiling
  • MPP_SESSION_BUDGET — Maximum deposit per session
  • MPP_MAX_CONCURRENT_SESSIONS — Limit active sessions
  • MPP_MAX_SESSION_DURATION — Maximum session length
  • MPP_ALLOWED_SERVICES — Allowlist of service domains
  • MPP_BLOCKED_SERVICES — Blocklist of service domains

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Supported Chain

MPP payments are currently supported on the Tempo blockchain:
PropertyValue
NetworkTempo Mainnet
Chain ID4217
CurrencyUSDC.e
Explorerhttps://explore.tempo.xyz
For Tempo Testnet and demo flows, use chain 42431 with pathUSD.

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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