The agent harness native to your app

npm install nativeharness

import { Harness } from "nativeharness";

const harness = new Harness({ model: new AnthropicAdapter() });
const workspace = await harness.workspace({ actor: "user-42" });

for await (const event of workspace.chat("add a test for the parser")) {
  render(event);            // tokens, commands, output, approvals — in your UI
}

const harness = new Harness();
const workspace = await harness.workspace({ actor: "user-42" });

await workspace.write("/main.js", "console.log(41 + 1)");
const { result } = await workspace.exec("node main.js");   // "42\n", plus what changed