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Advanced Usage 🚀

Level up your PAY.ID game! These are the pro patterns for production-grade integrations.

New to PAY.ID? Start with Simple Usage → first.

1️⃣ Complex Rule Patterns​

Nested Rules (VIP vs Normal Paths) 🎯​

Create different payment paths for different user types:

const VIP_RULE = {
  id: 'vip_or_normal',
  logic: 'OR' as const,
  rules: [
    {
      // VIP path: high amount + KYC3 + low risk
      id: 'vip_path',
      logic: 'AND' as const,
      rules: [
        { if: { field: 'tx.amount', op: '>=', value: '1000000000' } },  // >= 1000 USDC
        { if: { field: 'oracle.kycLevel', op: '==', value: '3' } },
        { if: { field: 'risk.score', op: '<=', value: '30' } },
      ],
    },
    {
      // Normal path: 5-500 USDC + ID + KYC1 + moderate risk
      id: 'normal_path',
      logic: 'AND' as const,
      rules: [
        { if: { field: 'tx.amount', op: 'between', value: ['5000000', '500000000'] } },  // 5-500 USDC
        { if: { field: 'oracle.country', op: '==', value: 'ID' } },
        { if: { field: 'oracle.kycLevel', op: '>=', value: '1' } },
        { if: { field: 'risk.score', op: '<=', value: '70' } },
      ],
    },
  ],
}

What this does: VIP users can send big amounts (1000+ USDC) if they have KYC3 and low risk. Normal users have smaller limits (5-500 USDC) with relaxed requirements. Smart, right?

Time-Based Rules (Business Hours) ⏰​

Only allow payments during work hours:

const BUSINESS_HOURS_RULE = {
  id: 'business_hours',
  if: {
    field: 'env.timestamp',
    op: 'between',
    value: ['9:00', '17:00'],
    transform: 'hour',
  },
  message: 'Payments only allowed during business hours (9 AM - 5 PM)',
}

Weekday-Only Rule 📅​

No weekend payments:

const WEEKDAY_RULE = {
  id: 'weekday_only',
  if: {
    field: 'env.timestamp',
    op: 'in',
    value: [1, 2, 3, 4, 5],  // Mon-Fri
    transform: 'day',
  },
  message: 'Payments only allowed on weekdays',
}

Cross-Field Validation (Daily Limit) 💰​

Track spending across all payments:

const DAILY_LIMIT_RULE = {
  id: 'daily_limit',
  if: {
    field: 'tx.amount',
    op: '<=',
    value: '$state.dailyLimit',
  },
  message: 'Exceeds daily spending limit',
}

2️⃣ Attestation-Gated Payments (EAS) 🔐​

Require EAS attestations before payment — perfect for KYC requirements:

// Server-side with Context V2
import { buildContextV2 } from 'payid/context'

const contextV2 = await buildContextV2({
  baseContext: {
    tx: { sender: payer, receiver: merchant, asset: USDC, amount: '50000000', chainId: 1 },
  },
  oracle: {
    issuer: oracleSigner,
    data: {
      kycLevel: '2',
      attestationUID: '0xabc123...',  // EAS attestation UID
    },
  },
})

// Rule checks for attestation
const ATTESTATION_RULE = {
  id: 'kyc_attestation',
  if: { field: 'oracle.attestationUID', op: 'exists' },
  message: 'KYC attestation required',
}

// Payment requires attestationUIDs
await payid.evaluateAndProve({
  context: contextV2,
  authorityRule: ATTESTATION_RULE,
  attestationUIDs: ['0xabc123...'],
  // ... other params
})

On-chain verification happens automatically via PayIDVerifier.requireAllowed() — pretty cool, right?

3️⃣ Context V2 with Server-Signed Data 📝​

Complete Context V2 Structure​

Here's the full Context V2 structure with all the bells and whistles:

import { buildContextV2 } from 'payid/context'

const contextV2 = await buildContextV2({
  baseContext: {
    tx: { sender, receiver, asset, amount, chainId },
  },
  // Environment timestamp signed by server
  env: {
    issuer: envSigner,
    data: { timestamp: Math.floor(Date.now() / 1000) },
  },
  // State tracking (spending limits)
  state: {
    issuer: stateSigner,
    data: {
      spentToday: '150000000',  // 150 USDC spent today
      dailyLimit: '500000000',  // 500 USDC daily limit
      period: 'DAY',
    },
  },
  // External oracle data (KYC, country, etc.)
  oracle: {
    issuer: oracleSigner,
    data: {
      kycLevel: '2',
      country: 'ID',
      riskScore: '25',
    },
  },
  // Risk scoring
  risk: {
    issuer: riskSigner,
    data: {
      score: 25,
      category: 'LOW',
      modelHash: '0x123...',
    },
  },
})

Trusted Issuers Setup 🔑​

Tell PAY.ID which signers you trust:

const payid = createPayIDServer({
  signer: serverSigner,
  trustedIssuers: new Set([
    '0xEnvSignerAddress...',
    '0xStateSignerAddress...',
    '0xOracleSignerAddress...',
    '0xRiskSignerAddress...',
  ]),
})

4️⃣ Session Policies (QR Codes) 📱​

Generate Session Policy​

Create a payment policy that customers can scan:

import { createSessionPolicyV2, encodeSessionPolicyV2QR } from 'payid/sessionPolicy'

const policy = await createSessionPolicyV2({
  receiver: merchantAddress,
  ruleSetHash: activeRuleSetHash,
  ruleAuthority: COMBINED_RULE_STORAGE,
  allowedAsset: USDC_ADDRESS,
  maxAmount: parseUnits('100', 6),  // Max 100 USDC per scan
  expiresAt: Math.floor(Date.now() / 1000) + 3600,  // Valid 1 hour
  payId: 'pay.id/my-shop',
  chainId: 31337,
  verifyingContract: PAYID_VERIFIER,
  signer: merchantSigner,
})

const qrString = encodeSessionPolicyV2QR(policy)
// → "payid-v2:eyJ2ZXJzaW9uIjoicGF5aWQuc2Vzc2lvbi5wb2xpY3kudjIi..."

Decode and Use Session Policy​

When someone scans your QR, decode it and use the policy:

import { decodeSessionPolicyV2QR } from 'payid/sessionPolicy'

const policy = decodeSessionPolicyV2QR(scannedQRString)

// Use with usePayIDFlow
execute({
  receiver: policy.receiver as `0x${string}`,
  asset: policy.allowedAsset as `0x${string}`,
  amount: BigInt(policy.maxAmount),
  payId: policy.payId,
  sessionPolicyV2: policy,  // Pass session policy
})

5️⃣ ERC-4337 Account Abstraction 🦊​

Build UserOperation from Proof​

Use PAY.ID with smart contract wallets:

import { createPayIDServer } from 'payid/server'

const payid = createPayIDServer({ signer: bundlerSigner })

const { proof } = await payid.evaluateAndProve({ /* ... */ })

// Build ERC-4337 UserOperation
const userOp = await payid.buildUserOperation({
  targetContract: PAY_WITH_PAYID,
  proof,
  attestationUIDs: [],
  sender: smartAccountAddress,
  nonce: 0n,
})

// Send to bundler
await bundler.sendUserOperation(userOp)

6️⃣ Custom State Tracking 📊​

Track Spending Limits​

Keep track of how much users spend on your server:

// Server maintains state
const userState = {
  spentToday: 0n,
  dailyLimit: 500_000_000n,  // 500 USDC
  period: new Date().toISOString().slice(0, 10),  // YYYY-MM-DD
}

// On each payment
userState.spentToday += amount

// Sign and include in context
const stateContext = await signState(userState, stateSigner)

const contextV2 = await buildContextV2({
  baseContext: { tx: { /* ... */ } },
  state: { issuer: stateSigner, data: userState },
})

Rule Enforces Limit​

The rule checks the state and blocks overspending:

const DAILY_LIMIT_RULE = {
  id: 'daily_limit',
  logic: 'AND' as const,
  rules: [
    { if: { field: 'state.spentToday', op: '<=', value: '$state.dailyLimit' } },
    { if: { field: 'state.period', op: '==', value: new Date().toISOString().slice(0, 10) } },
  ],
}

7️⃣ Risk Scoring Integration 🎯​

Risk-Based Payment Limits​

Adjust payment limits based on user risk score:

const RISK_BASED_RULE = {
  id: 'risk_limits',
  logic: 'OR' as const,
  rules: [
    {
      // Low risk: up to 1000 USDC
      id: 'low_risk',
      logic: 'AND' as const,
      rules: [
        { if: { field: 'risk.score', op: '<=', value: '30' } },
        { if: { field: 'tx.amount', op: '<=', value: '1000000000' } },
      ],
    },
    {
      // Medium risk: up to 100 USDC
      id: 'medium_risk',
      logic: 'AND' as const,
      rules: [
        { if: { field: 'risk.score', op: 'between', value: ['31', '70'] } },
        { if: { field: 'tx.amount', op: '<=', value: '100000000' } },
      ],
    },
    {
      // High risk: up to 10 USDC
      id: 'high_risk',
      logic: 'AND' as const,
      rules: [
        { if: { field: 'risk.score', op: '>', value: '70' } },
        { if: { field: 'tx.amount', op: '<=', value: '10000000' } },
      ],
    },
  ],
}

8️⃣ Directional Rules (INBOUND/OUTBOUND) ↔️​

Have different rules for receiving vs sending:

import { useActiveCombinedRuleByDirection } from 'payid-react'

// Get INBOUND rule (receiving payments)
const inboundPolicy = useActiveCombinedRuleByDirection(merchantAddress, 0)

// Get OUTBOUND rule (sending payments)
const outboundPolicy = useActiveCombinedRuleByDirection(userAddress, 1)

// Register directional rule
await registerCombinedRule({
  ruleSetHash: keccak256(toBytes('inbound-policy')),
  ruleNFTs: [ruleNFTAddress],
  tokenIds: [1n],
  version: 1n,
  direction: 0,  // INBOUND
})

9️⃣ Batch Payments 📦​

Pay multiple people at once:

import { usePayNative } from 'payid-react'

function BatchPay({ receivers }: { receivers: `0x${string}`[] }) {
  const { pay, isPending } = usePayNative()

  const handleBatchPay = async () => {
    for (const receiver of receivers) {
      await pay({
        decision: proofForReceiver,
        signature: signatureForReceiver,
        attestationUIDs: [],
      })
    }
  }

  return <button onClick={handleBatchPay} disabled={isPending}>Batch Pay</button>
}

🔟 Multi-Chain Deployment 🌐​

Configure Multiple Chains​

Deploy across multiple networks:

import { hardhat, polygon, base, mainnet } from 'wagmi/chains'

const wagmiConfig = createConfig({
  chains: [hardhat, polygon, base, mainnet],
  transports: {
    [hardhat.id]: http('http://127.0.0.1:8545'),
    [polygon.id]: http(),
    [base.id]: http(),
    [mainnet.id]: http(),
  },
})

const CONTRACT_ADDRESSES = {
  [hardhat.id]: { /* localhost addresses */ },
  [polygon.id]: { /* polygon addresses */ },
  [base.id]: { /* base addresses */ },
  [mainnet.id]: { /* mainnet addresses */ },
}

Chain-Specific Rules​

Different chains, different rules:

const chainId = useChainId()

// Different rules per chain
const RULES_BY_CHAIN = {
  1: ETHEREUM_RULES,      // Mainnet rules
  137: POLYGON_RULES,     // Polygon rules
  8453: BASE_RULES,       // Base rules
  31337: DEV_RULES,       // Localhost rules
}

const activeRules = RULES_BY_CHAIN[chainId] || DEFAULT_RULES

1️⃣1️⃣ Error Handling & Retry Logic 🔄​

Don't let network errors ruin the experience — retry automatically:

const { execute, status, error, reset } = usePayIDFlow()

const handlePayWithRetry = async () => {
  let retries = 3
  while (retries > 0) {
    try {
      await execute({ receiver, asset, amount, payId })
      break  // Success
    } catch (e) {
      retries--
      if (retries === 0) throw e
      await new Promise(r => setTimeout(r, 1000))  // Wait 1s
      reset()
    }
  }
}

1️⃣2️⃣ Subscription Management 💳​

Extend Rule Expiry​

Keep your rules active by renewing:

import { useExtendRuleExpiry } from 'payid-react'

function RenewRule({ tokenId }: { tokenId: bigint }) {
  const { extendRuleExpiry, isPending } = useExtendRuleExpiry()

  const handleRenew = () => {
    extendRuleExpiry({
      tokenId,
      newExpiry: BigInt(Math.floor(Date.now() / 1000) + 30 * 24 * 60 * 60),  // +30 days
      priceInWei: 100_000_000_000_000n,  // 0.0001 ETH
    })
  }

  return <button onClick={handleRenew} disabled={isPending}>Renew 30 Days</button>
}

Check Subscription Status​

Show users their subscription info:

import { useSubscription } from 'payid-react'

function SubscriptionBadge() {
  const { address } = useAccount()
  const { data: sub } = useSubscription(address)

  if (!sub?.isActive) {
    return <span style={{ color: 'red' }}>⚠️ Subscription Expired</span>
  }

  const daysLeft = Math.floor((Number(sub.expiry) - Date.now() / 1000) / 86400)

  return (
    <span>
      ✅ {sub.logicalRuleCount}/{sub.maxSlots} slots • {daysLeft} days left
    </span>
  )
}

1️⃣3️⃣ Custom IPFS Gateway 🌐​

<PayIDProvider
  contracts={CONTRACT_ADDRESSES}
  ipfsGateway="https://my-custom-ipfs-gateway.com/ipfs/"
>
  <App />
</PayIDProvider>

1️⃣4️⃣ Decision Proof Verification ✅​

Verify a proof on-chain:

import { useVerifyDecision } from 'payid-react'

function VerifyProof({ decision, signature }: { decision: any, signature: string }) {
  const { data: isValid, isLoading } = useVerifyDecision(decision, signature)

  if (isLoading) return <p>Verifying...</p>

  return <p>{isValid ? '✅ Valid Proof' : '❌ Invalid Proof'}</p>
}

1️⃣5️⃣ Nonce Management 🔒​

Check if a nonce was already used (prevents replay attacks):

import { useNonceUsed } from 'payid-react'

function CheckNonce({ payer, nonce }: { payer: `0x${string}`, nonce: string }) {
  const { data: used } = useNonceUsed(payer, nonce)

  if (used) {
    return <p style={{ color: 'red' }}>⚠️ Nonce already used - possible replay attack</p>
  }

  return <p>✅ Nonce is fresh</p>
}

Advanced Patterns Summary 📚​

PatternUse Case
Nested RulesVIP vs normal payment paths
Time-Based RulesBusiness hours, weekday-only
Attestation-GatedKYC-required payments
Context V2Server-signed oracle data
Session PoliciesQR code payments
ERC-4337Account abstraction
State TrackingSpending limits
Risk ScoringDynamic limits based on risk
Directional RulesSeparate INBOUND/OUTBOUND policies
Batch PaymentsMultiple recipients
Multi-ChainDeploy across networks
Retry LogicHandle transient failures
SubscriptionRule slot management

Next Steps 🎯​

You're now a PAY.ID pro! 🎉