PiHarness

This example runs the experimental PiHarness from Cloudflare Agents pull request 2197 in a celld Durable Object. The harness needs a model, and the example gets one from any OpenAI-compatible chat completions endpoint. It uses OpenRouter and Llama 3.2 1B by default.

The pi provider expects the ai.run() shape of a Workers AI binding, and celld serves no such binding, so the example builds a small adapter that posts each request to PI_ENDPOINT with OPENROUTER_API_KEY as the bearer token. The example stops at startup when a variable is absent, because a stand-in model answers every prompt and therefore hides a broken configuration. Set PI_ENDPOINT and PI_MODEL in wrangler.jsonc to use a different provider, such as a local server.

The agents package on npm does not contain PiHarness, therefore this example depends on a preview build of pull request 2197. The preview build can change or expire, so an install can fail until that pull request is released.

Install the dependencies, write the key to a .dev.vars file in this directory, then start the example. The agents package declares many peer dependencies that the example does not use, so leave them out:

npm install --legacy-peer-deps

echo 'OPENROUTER_API_KEY=sk-or-...' > .dev.vars

celld dev .

Run a prompt and inspect the persisted transcript:

curl http://127.0.0.1:9876/
curl http://127.0.0.1:9876/messages

The prompt route answers 200 for a completed run, and 502 with the reported errors for a failed one.

The Durable Object storage holds the transcript, so the state survives a restart. A model change does not migrate that state, therefore start again with celld dev --clean . after you edit PI_MODEL.