Pi Model Provider Native Prompting

Provider-informed, harness-neutral native-prompting guidance for Pi.

pi-model-provider-native-prompting adds a small prompt overlay to Pi's generated system prompt. It nudges the active model toward careful coding-agent behavior without adding tools, commands, permissions, task trackers, provider payload rewrites, or a replacement prompt.

Why This Exists

Model providers know their models best, and their native coding-agent harnesses encode hard-won lessons about planning, editing, validation, context use, and user-change safety.

Pi is its own harness. Claude-in-Pi is not Claude Code; a Codex model in Pi is not Codex CLI; Gemini in Pi is not Gemini CLI. This package distills only the portable, harness-neutral parts of those provider-native prompting patterns into Pi's active prompt.

It does not vendor, copy, or recreate Claude Code, Codex CLI, or Gemini CLI prompts.

Install

Install from npm:

pi install npm:pi-model-provider-native-prompting

Try it without installing:

pi -e npm:pi-model-provider-native-prompting

Install from GitHub:

pi install git:github.com/henryennis/pi-model-provider-native-prompting

Pin a release tag:

pi install git:github.com/henryennis/pi-model-provider-native-prompting@v0.2.3

What It Does

On each user prompt, the extension uses Pi's before_agent_start hook to insert a compact Model Provider Native Prompting Overlay into the current system prompt.

The overlay tells the model to:

• use only capabilities present in the active prompt or tool list,
• gather enough context before acting,
• make focused changes that match local conventions,
• avoid unrelated refactors and speculative abstractions,
• protect secrets and system configuration,
• avoid changing version-control state or discarding user work unless asked,
• ask for clarification only when ambiguity affects correctness,
• use context efficiently,
• validate work when the active project or harness provides a reasonable way,
• keep progress and final messages concise and path-aware.

The extension adds provider-family fragments for OpenAI, OpenAI Codex-family, Anthropic, and Google models, plus small capability fragments for reasoning-capable and small-context models.

What It Does Not Do

This package is intentionally prompt-only. It does not:

• add LLM-callable tools,
• add slash commands,
• add update_plan, todos, or task tracking,
• add permission gates or sandboxing,
• rewrite provider request payloads,
• modify tool calls or tool results,
• replace Pi's generated system prompt,
• copy Claude Code, Codex CLI, or Gemini CLI prompts.

Model family is not harness identity. The overlay explicitly tells the model not to assume optional harness capabilities unless they appear in the active instructions or tool list.

Model-Aware Behavior

Active model metadata	Added guidance
OpenAI provider/API or gpt-* id	OpenAI-family guidance
OpenAI Codex provider or codex id	OpenAI-family + OpenAI Codex-family guidance
Anthropic provider/API or claude id	Anthropic-family guidance
Google/Gemini provider/API/id	Google-family guidance
model.reasoning === true	Reasoning-model guidance
model.contextWindow < 64000	Small-context guidance
Unknown/custom model	Universal overlay only

Provider fragments are additive; they never replace the universal overlay. Codex-family models also receive OpenAI-family guidance because Codex is an OpenAI model family.

Compatibility

• Tested with Pi Coding Agent 0.72.1.
• Requires a Pi version that supports the before_agent_start extension event with a current system prompt.
• Runtime dependencies: none.
• Build step: none.

The package is dependency-free JavaScript ESM so Pi can load it directly.

Local Development

From this repository:

npm run check
npm run pack:dry-run

Run with a local checkout without writing Pi settings:

pi -e .

A no-LLM smoke test:

PI_OFFLINE=1 pi --no-session --no-extensions -e .

Confirm the startup header lists model-provider-native-prompting.js under [Extensions].

Debugging

There is no debug command because the extension has no runtime state and no configuration. To inspect what will be inserted, read extensions/model-provider-native-prompting.js; the exported overlay helpers are covered by tests.

If behavior seems wrong:

1. Run pi --no-extensions -e . from the checkout to isolate this package from other extensions.
2. Check that the model metadata matches the expected provider family.
3. Check for an existing <!-- pi-model-provider-native-prompting --> marker in the prompt; duplicate insertion is intentionally skipped.

Uninstall

If installed from npm:

pi remove npm:pi-model-provider-native-prompting

If installed from GitHub:

pi remove git:github.com/henryennis/pi-model-provider-native-prompting

Design Notes

This package came from comparing the harness-agnostic subset of Pi, OpenAI Codex CLI, Claude Code, and Gemini CLI. The result is intentionally anti-unified: a small behavioral overlay rather than a port of any one harness.

For project history and security reporting, see the repository files on GitHub:

• CHANGELOG.md
• SECURITY.md

License

MIT