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What is the Policy Engine?

The Policy Engine is an on-chain rule system that governs how funds can move from a Money Account. It enables automated controls without sacrificing security.

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Policy Types

PolicyDescription
Spend LimitsMaximum per-transaction or daily limits
Token WhitelistOnly approved tokens can be spent
Recipient WhitelistOnly approved addresses can receive
Time WindowsRestrict transactions to business hours
Approval ThresholdsMulti-sig for large amounts
Automation RulesPre-approved recurring payments

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How Policies Work

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Example Policies

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Spend Limit

{
  "type": "spend_limit",
  "config": {
    "perTransaction": "1000.00",
    "daily": "5000.00",
    "monthly": "50000.00",
    "token": "USDC"
  }
}

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Recipient Whitelist

{
  "type": "recipient_whitelist",
  "config": {
    "addresses": [
      "0x...",
      "supplier@stableyard",
      "payroll@company"
    ]
  }
}

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Time Window

{
  "type": "time_window",
  "config": {
    "allowedDays": ["monday", "tuesday", "wednesday", "thursday", "friday"],
    "allowedHours": { "start": 9, "end": 18 },
    "timezone": "Asia/Bangkok"
  }
}

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Recurring Payment

{
  "type": "recurring",
  "config": {
    "recipient": "landlord@stableyard",
    "amount": "2000.00",
    "frequency": "monthly",
    "dayOfMonth": 1,
    "autoExecute": true
  }
}

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Enterprise Use Cases

Treasury Controls

Limit daily outflows, require multi-sig for large transfers

Payroll Automation

Pre-approve monthly salary disbursements

Vendor Payments

Whitelist approved suppliers, set payment limits

Compliance

Enforce transaction limits for AML compliance

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Agentic Payments (x402+)

The Policy Engine enables AI agent payments with controlled autonomy:
ScenarioPolicy
API usage billingPer-request limit: $0.10
SaaS subscriptionMonthly cap: $500
Data purchaseDaily limit: $100
Tool accessPer-session: $5

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Agent Flow

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Policy Hierarchy

Policies can be layered:
LevelScopeExample
AccountAll transactionsDaily limit $10,000
TokenSpecific assetUSDC only to whitelisted
RecipientSpecific addressUnlimited to payroll vault
SessionTemporaryAgent session cap $50

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Gasless Execution

Policies enable gasless transactions:
  1. User pre-approves a policy
  2. Stableyard relayer executes transactions
  3. Gas paid from user’s USDC balance
  4. No native token required
Next: Learn about Merchant Layer — QR payments, links, and checkout.