diff --git a/package.json b/package.json
index 8996086..e5f1d9a 100644
--- a/package.json
+++ b/package.json
@@ -3,6 +3,10 @@
   "version": "0.0.0",
   "type": "module",
   "exports": "./src/index.ts",
+  "engines": {
+    "node": ">=22"
+  },
+  "packageManager": "pnpm@10.33.0",
   "scripts": {
     "test": "node --experimental-strip-types --test test/**/*.test.ts"
   }
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
new file mode 100644
index 0000000..9b60ae1
--- /dev/null
+++ b/pnpm-lock.yaml
@@ -0,0 +1,9 @@
+lockfileVersion: '9.0'
+
+settings:
+  autoInstallPeers: true
+  excludeLinksFromLockfile: false
+
+importers:
+
+  .: {}
diff --git a/src/index.ts b/src/index.ts
new file mode 100644
index 0000000..57ddd22
--- /dev/null
+++ b/src/index.ts
@@ -0,0 +1,2 @@
+export { mo } from './mo.ts';
+export { Task } from './task.ts';
diff --git a/src/mo.ts b/src/mo.ts
new file mode 100644
index 0000000..feea66e
--- /dev/null
+++ b/src/mo.ts
@@ -0,0 +1,18 @@
+import { registry } from './registry.ts';
+import { Task } from './task.ts';
+
+const counters = new Map<string, number>();
+
+export function mo<A extends unknown[], R>(
+  importMeta: ImportMeta,
+  fn: (...args: A) => R,
+): (...args: A) => Task<R> {
+  const url = importMeta.url;
+  const index = counters.get(url) ?? 0;
+  counters.set(url, index + 1);
+  const id = `${url}#${index}`;
+
+  registry.set(id, fn);
+
+  return (...args: A) => new Task<R>(id, args);
+}
diff --git a/src/registry.ts b/src/registry.ts
new file mode 100644
index 0000000..2431bb0
--- /dev/null
+++ b/src/registry.ts
@@ -0,0 +1 @@
+export const registry = new Map<string, (...args: any[]) => any>();
diff --git a/src/task.ts b/src/task.ts
new file mode 100644
index 0000000..16a3140
--- /dev/null
+++ b/src/task.ts
@@ -0,0 +1,16 @@
+export class Task<T> {
+  readonly id: string;
+  readonly args: unknown[];
+
+  constructor(id: string, args: unknown[]) {
+    this.id = id;
+    this.args = args;
+  }
+
+  then<T1 = T, T2 = never>(
+    onfulfilled?: ((value: T) => T1 | PromiseLike<T1>) | null,
+    onrejected?: ((reason: any) => T2 | PromiseLike<T2>) | null,
+  ): Promise<T1 | T2> {
+    throw new Error('Not implemented: wire up dedicated runner');
+  }
+}
diff --git a/test/mo.test.ts b/test/mo.test.ts
new file mode 100644
index 0000000..d5f57ea
--- /dev/null
+++ b/test/mo.test.ts
@@ -0,0 +1,33 @@
+import { describe, it } from 'node:test';
+import assert from 'node:assert/strict';
+import { mo } from 'moroutine';
+
+describe('mo()', () => {
+  it('returns a function', () => {
+    const double = mo(import.meta, (x: number) => 2 * x);
+    assert.equal(typeof double, 'function');
+  });
+
+  it('calling it returns a Task with correct args', () => {
+    const double = mo(import.meta, (x: number) => 2 * x);
+    const task = double(2);
+    assert.deepEqual(task.args, [2]);
+  });
+
+  it('Task is a thenable', () => {
+    const double = mo(import.meta, (x: number) => 2 * x);
+    const task = double(2);
+    assert.equal(typeof task.then, 'function');
+  });
+
+  it('tasks from the same moroutine share an id', () => {
+    const double = mo(import.meta, (x: number) => 2 * x);
+    assert.equal(double(1).id, double(2).id);
+  });
+
+  it('different moroutines have different ids', () => {
+    const a = mo(import.meta, (x: number) => x + 1);
+    const b = mo(import.meta, (x: number) => x + 2);
+    assert.notEqual(a(1).id, b(1).id);
+  });
+});