feat: add wrapClient for in-place mcp client payment injection

.changeset/mcp-client-inject.md

@@ -0,0 +1,5 @@
+---
+'mppx': patch
+---
+
+Added `wrapClient` to `mppx/mcp/client` for adding automatic payment handling to an SDK-owned MCP client in place: the client is mutated and the same reference is returned, the MCP SDK `callTool(params, resultSchema?, options?)` signature is preserved (method `context` is passed via the options argument), and payment challenges returned as tool results via `org.paymentauth/payment-required` metadata are handled alongside payment-required errors.

.changeset/mcp-entrypoints.md

@@ -0,0 +1,5 @@
+---
+'mppx': patch
+---
+
+Moved the MCP entrypoints to `mppx/mcp/client` and `mppx/mcp/server`; the `mppx/mcp-sdk/client` and `mppx/mcp-sdk/server` specifiers remain as aliases.

package.json

@@ -115,15 +115,25 @@
       "types": "./dist/evm/server/index.d.ts",
       "default": "./dist/evm/server/index.js"
     },
+    "./mcp/client": {
+      "src": "./src/mcp/client/index.ts",
+      "types": "./dist/mcp/client/index.d.ts",
+      "default": "./dist/mcp/client/index.js"
+    },
+    "./mcp/server": {
+      "src": "./src/mcp/server/index.ts",
+      "types": "./dist/mcp/server/index.d.ts",
+      "default": "./dist/mcp/server/index.js"
+    },
     "./mcp-sdk/client": {
-      "src": "./src/mcp-sdk/client/index.ts",
-      "types": "./dist/mcp-sdk/client/index.d.ts",
-      "default": "./dist/mcp-sdk/client/index.js"
+      "src": "./src/mcp/client/index.ts",
+      "types": "./dist/mcp/client/index.d.ts",
+      "default": "./dist/mcp/client/index.js"
     },
     "./mcp-sdk/server": {
-      "src": "./src/mcp-sdk/server/index.ts",
-      "types": "./dist/mcp-sdk/server/index.d.ts",
-      "default": "./dist/mcp-sdk/server/index.js"
+      "src": "./src/mcp/server/index.ts",
+      "types": "./dist/mcp/server/index.d.ts",
+      "default": "./dist/mcp/server/index.js"
     },
     "./proxy": {
       "src": "./src/proxy/index.ts",

src/Mcp.ts

@@ -13,6 +13,9 @@ export const paymentVerificationFailedCode = -32043
 /** MCP metadata key for credentials. */
 export const credentialMetaKey = 'org.paymentauth/credential'
 
+/** MCP metadata key for payment-required tool results. */
+export const paymentRequiredMetaKey = 'org.paymentauth/payment-required'
+
 /** MCP metadata key for receipts. */
 export const receiptMetaKey = 'org.paymentauth/receipt'
 
@@ -45,6 +48,7 @@ export type JsonRpcRequest = Request & {
  */
 export type Result = {
   _meta?: {
+    [paymentRequiredMetaKey]?: ErrorObject['data']
     [receiptMetaKey]?: Receipt
     [key: string]: unknown
   }

src/mcp-sdk/client/McpClient.test-d.ts → src/mcp/client/McpClient.test-d.ts

@@ -115,3 +115,76 @@ describe('McpClient.wrap.CallToolOptions', () => {
     expectTypeOf<Options>().toHaveProperty('timeout')
   })
 })
+
+describe('McpClient.wrapClient', () => {
+  test('returns the original client with payment-aware callTool', () => {
+    const client = {} as Client
+    const wrapped = McpClient.wrapClient(client, {
+      methods: [
+        tempo({
+          account: {} as Account,
+        }),
+      ],
+    })
+
+    expectTypeOf(wrapped).toEqualTypeOf<
+      McpClient.wrapClient.McpClient<Client, readonly [ReturnType<typeof tempo>]>
+    >()
+    expectTypeOf(wrapped.callTool).toBeFunction()
+    expectTypeOf(wrapped.callTool).returns.toExtend<Promise<McpClient.CallToolResult>>()
+  })
+
+  test('callTool keeps the MCP SDK result schema and options positions', () => {
+    const client = {} as Client
+    const wrapped = McpClient.wrapClient(client, {
+      methods: [
+        tempo({
+          account: {} as Account,
+        }),
+      ],
+    })
+
+    expectTypeOf(wrapped.callTool).toBeCallableWith({ name: 'tool' }, undefined, {
+      timeout: 5000,
+    })
+  })
+
+  test('callTool accepts context in the options position', () => {
+    const client = {} as Client
+    const wrapped = McpClient.wrapClient(client, {
+      methods: [tempo({})],
+    })
+
+    expectTypeOf(wrapped.callTool).toBeCallableWith({ name: 'tool' }, undefined, {
+      context: { account: {} as Account },
+      timeout: 5000,
+    })
+  })
+
+  test('can store an inferred client as the exported client type', () => {
+    const client = {} as Client
+
+    const wrapped = McpClient.wrapClient(client, {
+      methods: [tempo({ account: {} as Account })],
+    })
+
+    expectTypeOf(wrapped).toMatchTypeOf<McpClient.wrapClient.McpClient>()
+  })
+})
+
+describe('McpClient.wrapClient.McpClient', () => {
+  test('has callTool with correct signature', () => {
+    type WrappedClient = McpClient.wrapClient.McpClient
+
+    expectTypeOf<WrappedClient>().toHaveProperty('callTool')
+  })
+})
+
+describe('McpClient.wrapClient.CallToolOptions', () => {
+  test('has context and timeout properties', () => {
+    type Options = McpClient.wrapClient.CallToolOptions
+
+    expectTypeOf<Options>().toHaveProperty('context')
+    expectTypeOf<Options>().toHaveProperty('timeout')
+  })
+})