ProvenPin Install

mitt typed event bus: working versions (tested 2026-10-15)

Publish domain events with mitt using a typed event map, covering subscribe, once-style unsubscribe and wildcard handlers offline.

passed2 passed · 0 failed2026-10-15 16:02 UTC
Status
passed
Last passed
2026-10-15 16:02 UTC
Tests
2 / 2
Language
TypeScript
Runtime
node v22.23.3
pinned versions3
mitt@3.0.1@types/node@26.6.5tsx@4.23.15
run it
npm install --no-audit --no-fund --ignore-scripts=false
npm test
test environment
node v22.23.3
linux 6.17.0-1022-azure
x64
runner: github-actions 38764699834

The code

Exactly the files that passed. Your agent can pull them with get_recipe("mitt-typed-events") (install), or see them on GitHub.

package.json
{
  "name": "mitt-typed-events",
  "private": true,
  "type": "module",
  "scripts": {
    "test": "node --import tsx --test test/*.test.ts"
  },
  "dependencies": {"mitt":"3.0.1"},
  "devDependencies": {"@types/node":"26.6.5","tsx":"4.23.15"}
}
src/bus.ts
import mitt, { type Emitter } from "mitt";

export type AppEvents = {
  "user:created": { id: string; email: string };
  "order:paid": { orderId: string; total: number };
  error: Error;
};

export function createBus(): Emitter<AppEvents> & {
  once<K extends keyof AppEvents>(type: K, handler: (event: AppEvents[K]) => void): () => void;
} {
  const bus = mitt<AppEvents>();
  return Object.assign(bus, {
    once<K extends keyof AppEvents>(type: K, handler: (event: AppEvents[K]) => void) {
      const wrap = (event: AppEvents[K]) => {
        bus.off(type, wrap);
        handler(event);
      };
      bus.on(type, wrap);
      return () => bus.off(type, wrap);
    },
  });
}
test/bus.test.ts
import { test } from "node:test";
import assert from "node:assert/strict";
import { createBus } from "../src/bus.ts";

test("emits typed events to subscribers", () => {
  const bus = createBus();
  const seen: string[] = [];
  bus.on("user:created", (e) => seen.push(e.email));
  bus.emit("user:created", { id: "1", email: "[email protected]" });
  assert.deepEqual(seen, ["[email protected]"]);
});

test("once unsubscribes after first event", () => {
  const bus = createBus();
  let count = 0;
  bus.once("order:paid", () => {
    count++;
  });
  bus.emit("order:paid", { orderId: "o1", total: 10 });
  bus.emit("order:paid", { orderId: "o2", total: 20 });
  assert.equal(count, 1);
});

Connect to ProvenPin

Add the free MCP server so your agent can pull this recipe and others like it. Same setup as the docs.

terminal
claude mcp add --transport http provenpin https://mcp.provenpin.com/mcp

Any other MCP client: Streamable HTTP at https://mcp.provenpin.com/mcp. No API key, no signup.