@nwire/handler — alone

The operation primitive. One typed function declaration that can run on HTTP, on a queue worker, or as an MCP tool — the transport adapter decides where.

What it does

• defineHandler({ name, input, handler }) produces a typed operation.
• The same definition can be wired through httpInterface().wire(binding, handler) (HTTP), queueInterface().from(topic).wire(handler) (BullMQ / NATS), or mcpInterface().wire(handler) (Model Context Protocol).
• No transport coupling in your handler body — ctx is the same shape across all of them.

Install

pnpm add @nwire/handler zod

Declare once

import { defineHandler } from "@nwire/handler"
import { z } from "zod"

export const summarizeText = defineHandler({
  name: "ai.summarize-text",
  input: z.object({ text: z.string().max(50_000) }),
  handler: async ({ input }) => ({
    summary: await callLLM(input.text),
  }),
})

Mount it on HTTP

import { httpInterface } from "@nwire/http"
import { mountHandler } from "@nwire/handler/http"

const api = httpInterface()
mountHandler(api, "POST /summarize", summarizeText)

Mount it on a queue

import { Worker } from "bullmq"
import { runHandler } from "@nwire/handler"

new Worker("summaries", async (job) => {
  return runHandler(summarizeText, { input: job.data })
})

Mount it as an MCP tool

import { mcpServer } from "@nwire/mcp"
import { handlerAsMcpTool } from "@nwire/handler/mcp"

const server = mcpServer({ name: "ai-tools" })
server.addTool(handlerAsMcpTool(summarizeText))

When to use this and not defineAction

defineAction is the L4 form — it carries persona / journeyStep / emits + binds to actors and projections. defineHandler is the L1-style operation primitive without the domain machinery. Use it when:

• You want one operation surface across HTTP + queue + MCP and your code is procedural (no actor, no event emission).
• You're building an LLM tool, an internal admin endpoint, or a wrapper around a third-party API.

If you find yourself wanting events, actors, or projections, climb to defineAction in @nwire/forge.