# PRD 0058: Add built-in Pi agent provider

- **Status:** Active
- **Author:** codex
- **Created:** 2026-06-09
- **Issue:** #221

## Summary

Add `pi` as a built-in `agent_provider.template`. The provider runs the Pi
coding-agent CLI, provisions its agent config under `~/.pi/agent`, and writes a
provider settings file that targets an unauthenticated Ollama-compatible server.

The default settings assume an Ollama server at `http://ollama:11434/v1`, using
the `openai-completions` API with a dummy API key because Ollama ignores it.
Users can override the provider id, base URL, model list, API key, API-key env
reference, API type, and compatibility flags through a new
`agent_provider.settings` object.

## Problem

bot-bottle currently ships Claude and Codex as built-in agent providers. Pi is a
useful third harness, but using it today requires a custom provider plugin and a
custom image. That repeats boilerplate for prompt copying, skill copying,
provider config, and runtime registration.

Pi's local-model path is also easy to misconfigure: its custom-model docs require
`~/.pi/agent/models.json`, an API entry, at least one model id, and a dummy
`apiKey` for Ollama even though the server does not authenticate. bot-bottle
should generate that shape consistently.

## Goals / Success Criteria

- `agent_provider.template: pi` is accepted as a built-in provider.
- `bot_bottle/contrib/pi/` provides a Pi image and `PiAgentProvider`.
- Pi receives the bot-bottle prompt at `~/.bot-bottle-prompt.txt` and starts in
  print-mode prompt delivery like Codex.
- Pi skills are copied into `~/.pi/agent/skills/<name>/`.
- Pi provider settings are configurable from the bottle manifest via
  `agent_provider.settings`.
- The default Pi provider settings configure an unauthenticated Ollama-compatible
  server.
- Unit tests cover manifest parsing, runtime selection, plan generation, prompt,
  skills, and provider provisioning.

## Non-goals

- Managing or launching an Ollama server.
- Authenticating to Ollama or any remote Pi provider.
- Forwarding host Pi credentials.
- Implementing Pi extensions or MCP registration.
- Changing Claude or Codex provider behavior.

## Design

### Manifest

Extend `agent_provider` with an optional `settings` object. It is currently only
supported for built-in `pi`.

Supported keys:

- `base_url`: string, defaults to `http://ollama:11434/v1`
- `provider`: string, defaults to `ollama`
- `api`: string, defaults to `openai-completions`
- `api_key`: string, defaults to `ollama`
- `api_key_env`: string, optional host env var name for egress auth injection
- `models`: non-empty array of strings, defaults to `["qwen2.5-coder:7b"]`
- `context_window`: positive integer, defaults to `4096`; this is the Ollama
  runtime context, and bot-bottle subtracts `max_tokens` before writing Pi's
  `contextWindow` so output space is reserved
- `max_tokens`: positive integer, defaults to `1024`
- `max_tokens_field`: `max_tokens` or `max_completion_tokens`, defaults to
  `max_tokens`
- `supports_developer_role`: boolean, defaults to `false`
- `supports_reasoning_effort`: boolean, defaults to `false`

The snake-case manifest keys are converted into Pi's JSON field names:
`baseUrl`, `apiKey`, `contextWindow`, `maxTokens`,
`supportsDeveloperRole`, and `supportsReasoningEffort`. `context_window`
describes the server's total context; Pi's `contextWindow` receives
`context_window - max_tokens` because Pi uses it as an input compaction target.

`api_key` and `api_key_env` are mutually exclusive. When targeting a hosted
provider through bot-bottle's egress sidecar, omit `api_key` and set
`api_key_env` to the host env var that holds the API key. The generated
`models.json` receives only an `egress-placeholder` API key, and the egress
route injects the real `Authorization` header from the sidecar env. For example,
OpenRouter can use provider id `openrouter` with
`api_key_env: OPENROUTER_API_KEY`, keeping the key out of the agent env and
`models.json`.

### Provider

`PiAgentProvider.provision_plan` writes `models.json` into the per-launch state
directory and returns an `AgentProvisionPlan` that copies it to
`~/.pi/agent/models.json`. The provider also declares an unauthenticated egress
route for the configured base URL host so the egress layer can allow the Ollama
endpoint.

The Pi runtime uses:

- `command="pi"`
- `prompt_mode="append_system_prompt"`
- `image="bot-bottle-pi:latest"`
- `bypass_args=()`
- `resume_args=()`
- `remote_control_args=()`

The Dockerfile installs `@earendil-works/pi-coding-agent` globally from npm and
keeps the same Debian/node base shape as the existing provider images.

### Supervise MCP

Pi does not have built-in MCP support in the current public docs, so
`provision_supervise_mcp` is a no-op. This keeps Pi bottles launchable with
`supervise: true` while preserving the explicit non-goal of implementing Pi
extensions.

## Merge rule(s)

This PR can merge when the focused unit tests pass and the PRD status is flipped
from Draft to Active in the final implementation commit.
