Pi

Pi is a minimal, extensible terminal coding agent. LowRouter has a provider package for it, @lowrouter/pi-provider. Without the package, Pi also takes LowRouter as a custom provider in models.json.

Install the package

The package needs Pi 1.3.0 or later, which needs Node.js 22.19 or later.

npm install -g @earendil-works/pi-coding-agent@latest
pi install npm:@lowrouter/pi-provider

Add your key in one of two ways. You can export it:

export LOWROUTER_API_KEY=sk-lr-...

Or store it in Pi: run /login in a session and pick LowRouter.

Then pick a model:

pi --list-models lowrouter
pi --model lowrouter/auto/mistralai/mistral-large-2512

You can also switch with /model in a session.

What the package does:

• It reads the model list from LowRouter when Pi starts, when the /model picker refreshes, and on pi update --models. A new model shows up without a package update. Pi keeps the last list for offline starts.
• It lists auto/ chat models with function calling, plus your account’s alias/ models. Context windows and output limits come from the same list, so you don’t set them yourself.
• Pi shows costs in US dollars. The package uses the price of each model’s most expensive route, so Pi’s estimate is an upper bound. You are billed in euros, for the route that served the request.

Jurisdiction-scoped IDs such as auto/mistralai/mistral-large-2512/eu and pinned routes are not in the list. To use one, add it to models.json as shown below.

The package’s source and release notes are on GitHub.

Without the package

Verified against Pi 1.3.0. The config below is re-run against that release every week, including a tool call round trip.

Configure

Add LowRouter as a provider in ~/.pi/agent/models.json:

{
  "providers": {
    "lowrouter": {
      "name": "LowRouter",
      "baseUrl": "https://api.lowrouter.ai/v1",
      "api": "openai-completions",
      "apiKey": "$LOWROUTER_API_KEY",
      "compat": { "supportsDeveloperRole": false, "supportsStore": false },
      "models": [
        {
          "id": "auto/mistralai/mistral-large-2512",
          "name": "Mistral Large (LowRouter)",
          "input": ["text", "image"],
          "contextWindow": 256000,
          "maxTokens": 8192
        }
      ]
    }
  }
}

$LOWROUTER_API_KEY is read from the environment, so the key stays out of the file:

export LOWROUTER_API_KEY=sk-lr-...
pi --model lowrouter/auto/mistralai/mistral-large-2512

Details of this config:

• The model reference is lowrouter/ followed by the LowRouter model ID. Pi splits on the first slash only, so the slashes inside the ID are fine.
• baseUrl ends in /v1. Pi appends /chat/completions.
• contextWindow is what Pi plans compaction around, and maxTokens caps the answer length it asks for. Without them Pi assumes 128,000 and 16,384, which some models reject. Take both from the model browser.
• compat turns off the developer role and the store field. Some of the upstream hosts LowRouter routes to reject them.
• Each additional model is another entry in models. A scoped ID such as auto/mistralai/mistral-large-2512/eu or a pinned route goes in the same list.
• If the package is installed too, entries in models.json add to the package’s list or replace entries that have the same ID.

Picking a model

Pi works through tools: it reads, edits and writes files and runs commands. Pick a model with the function-calling tag; the model browser filtered to them lists every one.

The example uses auto/mistralai/mistral-large-2512, served from the EU (256k context). Other models we have run through Pi’s tool loop:

• auto/mistralai/mistral-small-2603, a smaller, cheaper Mistral model served from the EU (256k context).
• auto/openai/gpt-5.5 (1M context).

Recommended setup

• Use a dedicated key, so Pi’s spend shows separately and can be revoked on its own.
• Without the package, give each model its real contextWindow and a maxTokens within the model’s output limit. The package reads both from LowRouter.

Troubleshooting

• “No models available”: Pi lists a provider’s models only once it has a key. Export LOWROUTER_API_KEY or run /login, then try again.
• pi install fails, or the package never loads: check node --version. Pi needs 22.19 or later.
• pi -p in a script prints nothing and never exits: print mode reads piped stdin. Close it with </dev/null.
• A 401 naming a malformed key: the key was cut off when copied. Copy it again in full, or create a new one at /app/keys.
• A 400 about output tokens: the model’s output limit is lower than maxTokens (or the 16,384 default). Lower maxTokens for that model entry.
• Something else is off: run pi -ne to start without extensions and rule out a conflict with another package. -ne also turns off the LowRouter package, so LowRouter models are then available only from models.json.