Overview

Pi (slug pi) is a coding agent CLI driven non-interactively through its --print mode. It reaches its model through OpenRouter, so a Pi run reports OpenRouter-style model IDs and is priced from the model’s list price. The harness itself is at pi.dev.

Model IDs

Every session is launched with --provider openrouter, so Pi’s model IDs are OpenRouter provider-prefixed slugs. The ID is passed to the CLI exactly as supplied, with no routing prefix added. Illustrative examples:

• z-ai/glm-5.2
• moonshotai/kimi-k2.7-code
• qwen/qwen3.7-plus

Invocation

The harness probes and invokes the pi binary, installed into the run container at run time with:

npm install -g --ignore-scripts @earendil-works/pi-coding-agent && npm cache clean --force

A session runs in --print mode with JSON output. The Test Cabinet passes these flags:

Flag	Purpose
--mode json	Emit the line-delimited JSON event stream consumed for events and usage.
--print	Run non-interactively, printing output rather than entering an interactive session.
--provider openrouter	Reach the model through OpenRouter.
--model <id>	The model to run.

The prompt is passed as the final positional argument.

Authentication and cost

Pi’s API key is sourced from OPENROUTER_API_KEY on the host and injected into the run container under the same name. See Authentication.

The model ID is already an OpenRouter slug, so it resolves as-is to the catalog entry the comparable cost is priced from. Pi reports no run cost of its own, so its actual cost equals the comparable cost. See Metrics.