BillingMcp

The surfaces an Api projects onto, without a second declaration.

Source: packages/paykit/src/Surfaces.ts Kind: Layer

The surfaces an Api projects onto, without a second declaration.

This module is a separate entry point (@potion.run/paykit/Surfaces) because it loads effect/ai and effect/cli. An app that serves only HTTP never imports it, and never pays for them.

An Api is the unit of authorization: toMcp runs every tool call through the Api’s own middleware, using the MCP request’s headers, so the tenant MCP server authenticates exactly as the tenant HTTP surface does. Serve the two Apis at two paths; never merge them.

Serving tools to an agent

import { McpProtocol, McpServer } from "effect/ai";
import * as HttpRouter from "effect/http/HttpRouter";
import { BillingMcp } from "@potion.run/paykit/Surfaces";
import { BillingLive } from "./Billing.ts";

const Mcp = BillingMcp.pipe(
  Layer.provide(
    McpServer.layerHttp({ name: "billing", version: "1.0.0", path: "/mcp", protocols: [McpProtocol.v2025_11_25] }),
  ),
  Layer.provide(BillingLive),
);

export const { handler } = HttpRouter.toWebHandler(Mcp);