Initial commit: demo todo CLI with Claude Code setup

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

test/todo.test.js

@@ -0,0 +1,23 @@
+import { test } from "node:test";
+import assert from "node:assert/strict";
+import { add, complete, remove, format } from "../src/todo.js";
+
+test("add appends an open todo", () => {
+  const todos = add([], "buy milk");
+  assert.deepEqual(todos, [{ id: 1, text: "buy milk", done: false }]);
+});
+
+test("complete marks only the matching todo", () => {
+  const todos = complete(add(add([], "a"), "b"), 2);
+  assert.equal(todos[0].done, false);
+  assert.equal(todos[1].done, true);
+});
+
+test("remove drops the matching todo", () => {
+  const todos = remove(add(add([], "a"), "b"), 1);
+  assert.deepEqual(todos.map((t) => t.text), ["b"]);
+});
+
+test("format renders an empty list", () => {
+  assert.equal(format([]), "Nothing to do.");
+});