feat: add x402 exact support

.changeset/x402-exact-types.md

@@ -0,0 +1,5 @@
+---
+'mppx': patch
+---
+
+Added x402 exact core types, header codecs, known asset metadata, client/server transports, and public client/server interfaces.

.changeset/x402-resource-binding.md

@@ -0,0 +1,5 @@
+---
+'mppx': patch
+---
+
+Fixed x402 exact resource binding for submitted payment payloads.

README.md

@@ -78,6 +78,130 @@ Mppx.create({
 const res = await fetch('https://mpp.dev/api/ping/paid')
 ```
 
+### x402 Exact
+
+```ts
+import { Mppx, tempo, x402 } from 'mppx/server'
+
+const mppx = Mppx.create({
+  methods: [
+    tempo({
+      currency: '0x20c0000000000000000000000000000000000000',
+      recipient: '0x742d35Cc6634c0532925a3b844bC9e7595F8fE00',
+    }),
+    x402.exact({
+      config: {
+        currency: x402.assets.baseSepolia.USDC,
+        facilitator: 'https://x402.org/facilitator',
+        recipient: '0x742d35Cc6634c0532925a3b844bC9e7595F8fE00',
+      },
+    }),
+  ],
+})
+
+export async function GET(request: Request) {
+  const url = new URL(request.url)
+  const result =
+    url.pathname === '/mpp'
+      ? await mppx.tempo.charge({ amount: '1' })(request)
+      : await mppx.x402.exact({
+          amount: '0.01',
+          resource: { url: request.url },
+        })(request)
+
+  if (result.status === 402) return result.challenge
+  return result.withReceipt(Response.json({ data: 'paid content' }))
+}
+```
+
+Existing server adapters expose the same method. For Hono:
+
+```ts
+import { Hono } from 'hono'
+import { Mppx, tempo, x402 } from 'mppx/hono'
+
+const app = new Hono()
+const mppx = Mppx.create({
+  methods: [
+    tempo({
+      currency: '0x20c0000000000000000000000000000000000000',
+      recipient: '0x742d35Cc6634c0532925a3b844bC9e7595F8fE00',
+    }),
+    x402.exact({
+      config: {
+        currency: x402.assets.baseSepolia.USDC,
+        facilitator: 'https://x402.org/facilitator',
+        recipient: '0x742d35Cc6634c0532925a3b844bC9e7595F8fE00',
+      },
+    }),
+  ],
+})
+
+app.get('/mpp', mppx.tempo.charge({ amount: '1' }), (c) => c.json({ ok: true }))
+app.get('/x402', mppx.x402.exact({ amount: '0.01' }), (c) => c.json({ ok: true }))
+```
+
+Like Tempo, x402 route `amount` values are display-unit strings; mppx converts
+them to atomic token amounts from the configured currency decimals.
+
+To offer both protocols from one Hono route, use the core HTTP composer inside
+the Hono handler:
+
+```ts
+import { Hono } from 'hono'
+import { Mppx, tempo, x402 } from 'mppx/server'
+
+const app = new Hono()
+const tempoCharge = tempo.charge({
+  currency: '0x20c0000000000000000000000000000000000000',
+  recipient: '0x742d35Cc6634c0532925a3b844bC9e7595F8fE00',
+})
+const x402Exact = x402.exact({
+  config: {
+    currency: x402.assets.baseSepolia.USDC,
+    facilitator: 'https://x402.org/facilitator',
+    recipient: '0x742d35Cc6634c0532925a3b844bC9e7595F8fE00',
+  },
+})
+const payments = Mppx.create({
+  methods: [tempoCharge, x402Exact],
+})
+
+const paid = payments.compose([tempoCharge, { amount: '1' }], [x402Exact, { amount: '0.01' }])
+
+app.get('/paid', async (c) => {
+  const result = await paid(c.req.raw)
+  if (result.status === 402) return result.challenge
+  return result.withReceipt(c.json({ ok: true }))
+})
+```
+
+The same `compose()` handler can be used in other HTTP frameworks. Pass it the
+framework's standard `Request`, return `result.challenge` on `402`, and wrap the
+framework response with `result.withReceipt(...)` after payment succeeds.
+
+```ts
+import { privateKeyToAccount } from 'viem/accounts'
+import { Mppx, x402 } from 'mppx/client'
+
+const mppx = Mppx.create({
+  methods: [
+    x402.exact({
+      account: privateKeyToAccount('0x...'),
+      currencies: [x402.assets.baseSepolia.USDC],
+      maxAmount: '0.01',
+      networks: ['eip155:84532'],
+    }),
+  ],
+})
+
+const res = await mppx.fetch('https://api.example.com/paid')
+```
+
+The default HTTP transport multiplexes Payment auth and x402 headers. It reads
+`WWW-Authenticate` and `PAYMENT-REQUIRED`, then sends credentials through either
+`Authorization` or `PAYMENT-SIGNATURE` based on the selected challenge.
+
 ## Examples
 
 | Example                                                | Description                                          |

package.json

@@ -130,6 +130,21 @@
       "src": "./src/stripe/server/index.ts",
       "default": "./dist/stripe/server/index.js"
     },
+    "./x402": {
+      "types": "./dist/x402/index.d.ts",
+      "src": "./src/x402/index.ts",
+      "default": "./dist/x402/index.js"
+    },
+    "./x402/client": {
+      "types": "./dist/x402/client/index.d.ts",
+      "src": "./src/x402/client/index.ts",
+      "default": "./dist/x402/client/index.js"
+    },
+    "./x402/server": {
+      "types": "./dist/x402/server/index.d.ts",
+      "src": "./src/x402/server/index.ts",
+      "default": "./dist/x402/server/index.js"
+    },
     "./tempo": {
       "types": "./dist/tempo/index.d.ts",
       "src": "./src/tempo/index.ts",

pnpm-workspace.yaml

@@ -18,7 +18,7 @@ overrides:
   path-to-regexp@<8.4.0: '8.4.0'
   tar@<=7.5.10: '7.5.11'
   '@modelcontextprotocol/sdk@>=1.10.0 <=1.25.3': '1.26.0'
-  qs@>=6.7.0 <=6.14.1: '6.14.2'
+  qs@>=6.7.0 <=6.15.1: '6.15.2'
   ip-address@<=10.1.0: '10.1.1'
   minimatch@>=5.0.0 <5.1.8: '5.1.8'
   minimatch@>=9.0.0 <9.0.7: '9.0.7'

src/client/Methods.ts

@@ -2,3 +2,4 @@ export { stripe } from '../stripe/client/index.js'
 export { subscription } from '../tempo/client/Subscription.js'
 export { tempo } from '../tempo/client/index.js'
 export { session } from '../tempo/client/Session.js'
+export { x402 } from '../x402/client/index.js'

src/client/Mppx.ts

@@ -125,6 +125,7 @@ export function create<
     ...(resolvedOnChallenge && { onChallenge: resolvedOnChallenge }),
     ...(orderChallenges && { orderChallenges }),
     methods,
+    transport: transport as never,
   } satisfies Fetch.from.Config<FlattenMethods<methods>>
   const fetch = Fetch.from<FlattenMethods<methods>>(config_fetch)