Add expiry fields to PaymentRequirements example (#33)

## Summary

- Adds `preApprovalExpirySeconds`, `authorizationExpirySeconds`, and
`refundExpirySeconds` to the PaymentRequirements JSON example in the EVM
spec
- These fields were already documented in the extra fields table but
missing from the example, making them easy to overlook

## Context

Addresses review feedback asking whether expiries should be surfaced in
PaymentRequirements. They already were in the table, but the JSON
example didn't show them.

## Test plan

- [ ] Spec-only change, no code impact
- [ ] Verify example JSON is valid and fields match the table
descriptions

🤖 Generated with [Claude Code](https://claude.com/claude-code)

---------

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: A1igator

packages/evm/src/commerce/client/scheme.ts

@@ -64,15 +64,18 @@ export class CommerceEvmScheme implements SchemeNetworkClient {
 
     const chainId = parseChainId(requirements.network)
     const maxAmount = requirements.amount
+    const nowSeconds = Math.floor(Date.now() / 1000)
 
     const paymentInfo = {
       operator: operatorAddress,
       receiver: requirements.payTo as `0x${string}`,
       token: requirements.asset as `0x${string}`,
       maxAmount,
-      preApprovalExpiry: preApprovalExpirySeconds ?? MAX_UINT48,
-      authorizationExpiry: authorizationExpirySeconds ?? MAX_UINT48,
-      refundExpiry: refundExpirySeconds ?? MAX_UINT48,
+      preApprovalExpiry:
+        preApprovalExpirySeconds != null ? nowSeconds + preApprovalExpirySeconds : MAX_UINT48,
+      authorizationExpiry:
+        authorizationExpirySeconds != null ? nowSeconds + authorizationExpirySeconds : MAX_UINT48,
+      refundExpiry: refundExpirySeconds != null ? nowSeconds + refundExpirySeconds : MAX_UINT48,
       minFeeBps,
       maxFeeBps,
       feeReceiver: feeReceiver ?? zeroAddress,

packages/evm/test/unit/commerce/client.test.ts

@@ -1,7 +1,8 @@
-import { describe, it, expect, vi, beforeEach } from 'vitest'
+import { describe, it, expect, vi, beforeEach, afterEach } from 'vitest'
 import { CommerceEvmScheme } from '../../../src/commerce/client/index'
 import { x402Client } from '@x402/core/client'
 import { registerCommerceEvmScheme } from '../../../src/commerce/client/index'
+import { MAX_UINT48 } from '../../../src/commerce/shared/constants'
 
 describe('CommerceEvmScheme', () => {
   const createMockSigner = () => ({
@@ -15,6 +16,10 @@ describe('CommerceEvmScheme', () => {
     mockSigner = createMockSigner()
   })
 
+  afterEach(() => {
+    vi.restoreAllMocks()
+  })
+
   const mockRequirements = {
     scheme: 'commerce',
     network: 'eip155:84532',
@@ -153,6 +158,37 @@ describe('CommerceEvmScheme', () => {
       )
     })
 
+    it('should convert expirySeconds to absolute timestamps', async () => {
+      const fakeNow = 1700000000000 // fixed ms
+      vi.spyOn(Date, 'now').mockReturnValue(fakeNow)
+      const nowSeconds = 1700000000
+
+      const scheme = new CommerceEvmScheme(mockSigner)
+      const requirementsWithExpiries = {
+        ...mockRequirements,
+        extra: {
+          ...mockRequirements.extra,
+          preApprovalExpirySeconds: 3600,
+          authorizationExpirySeconds: 86400,
+          refundExpirySeconds: 604800,
+        },
+      }
+      const result = await scheme.createPaymentPayload(2, requirementsWithExpiries)
+
+      expect(result.payload.paymentInfo.preApprovalExpiry).toBe(nowSeconds + 3600)
+      expect(result.payload.paymentInfo.authorizationExpiry).toBe(nowSeconds + 86400)
+      expect(result.payload.paymentInfo.refundExpiry).toBe(nowSeconds + 604800)
+    })
+
+    it('should default expiries to MAX_UINT48 when not specified', async () => {
+      const scheme = new CommerceEvmScheme(mockSigner)
+      const result = await scheme.createPaymentPayload(2, mockRequirements)
+
+      expect(result.payload.paymentInfo.preApprovalExpiry).toBe(MAX_UINT48)
+      expect(result.payload.paymentInfo.authorizationExpiry).toBe(MAX_UINT48)
+      expect(result.payload.paymentInfo.refundExpiry).toBe(MAX_UINT48)
+    })
+
     it('should throw for invalid network format', async () => {
       const scheme = new CommerceEvmScheme(mockSigner)
       const badNetworkRequirements = {

specs/schemes/commerce/scheme_commerce_evm.md

@@ -36,7 +36,10 @@ Commerce-accepting servers advertise with scheme `commerce`:
         "settlementMethod": "authorize",
         "minFeeBps": 0,
         "maxFeeBps": 1000,
-        "feeReceiver": "0xOperatorAddress"
+        "feeReceiver": "0xOperatorAddress",
+        "preApprovalExpirySeconds": 3600,
+        "authorizationExpirySeconds": 86400,
+        "refundExpirySeconds": 604800
       }
     }
   ]
@@ -56,9 +59,9 @@ Commerce-accepting servers advertise with scheme `commerce`:
 | `minFeeBps`                  | No       | `uint16`                  | Minimum fee in basis points. Default: `0`          |
 | `maxFeeBps`                  | No       | `uint16`                  | Maximum fee in basis points. Default: `0`          |
 | `feeReceiver`                | No       | `address`                 | Fee recipient. Default: `address(0)` (no fees)     |
-| `preApprovalExpirySeconds`   | No       | `uint48`                  | ERC-3009 signature validity / pre-approval expiry  |
-| `authorizationExpirySeconds` | No       | `uint48`                  | Deadline for capturing escrowed funds              |
-| `refundExpirySeconds`        | No       | `uint48`                  | Deadline for refund requests                       |
+| `preApprovalExpirySeconds`   | No       | `uint48`                  | Seconds until pre-approval / ERC-3009 sig expires  |
+| `authorizationExpirySeconds` | No       | `uint48`                  | Seconds until capture deadline for escrowed funds  |
+| `refundExpirySeconds`        | No       | `uint48`                  | Seconds until refund request deadline              |
 
 ## PaymentPayload
 
@@ -94,7 +97,7 @@ Commerce-accepting servers advertise with scheme `commerce`:
       "to": "0xCollectorAddress",
       "value": "1000000",
       "validAfter": "0",
-      "validBefore": "1740672154",
+      "validBefore": "1740675754",
       "nonce": "0xf374...3480"
     },
     "signature": "0x2d6a...571c",
@@ -103,9 +106,9 @@ Commerce-accepting servers advertise with scheme `commerce`:
       "receiver": "0xReceiverAddress",
       "token": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
       "maxAmount": "1000000",
-      "preApprovalExpiry": 1740672154,
-      "authorizationExpiry": 4294967295,
-      "refundExpiry": 281474976710655,
+      "preApprovalExpiry": 1740675754,
+      "authorizationExpiry": 1740758554,
+      "refundExpiry": 1741276954,
       "minFeeBps": 0,
       "maxFeeBps": 1000,
       "feeReceiver": "0xOperatorAddress",