@askturret/mcp-transports

The wire layer: MCP's Streamable HTTP transport, plus the session storage it needs. This is what carries JSON-RPC between an agent and the runtime.

Most people never install this directly — the Express and Fastify adapters pull it in and wire it up. Install it yourself when you are serving MCP from a framework we do not ship an adapter for, or when you need to control session storage.

What it is for

import { createHttpTransport, createInMemorySessionStore } from '@askturret/mcp-transports';

const transport = createHttpTransport({
  sessionStore: createInMemorySessionStore(),
});

createHttpTransport gives you the request-handling half of a server; createInMemorySessionStore is a SessionStore implementation suitable for a single process.

Sessions

Streamable HTTP is stateless per request but MCP conversations are not, so session state is an explicit dependency rather than a hidden global. The in-memory store is the default and is the right choice for one process. It is not shared across instances: behind a load balancer, or anywhere requests for one session can land on different processes, implement SessionStore against something shared.

Making the store an interface rather than an implementation detail is the point — the transport does not care where session data lives.

Requirements

npm install @askturret/mcp-transports

@modelcontextprotocol/sdk is a peer dependency (^1.24.0) — install it yourself so there is exactly one copy of the protocol types in your tree. Node 20+.

What it does not do

It moves bytes and tracks sessions. It does not discover operations, compile them, apply policy or execute anything — all of that is @askturret/mcp-core.

It is also not a framework binding: it does not know about Express routers or Fastify plugins. If that is what you want, the adapters are thinner than doing it by hand.

Full documentation is in the main README.