pi-per-model-prompt

Model-scoped system prompt correction layers for pi.

This package ships a single pi extension that appends a small all-model harness core and then layers targeted model corrections on top. It stays intentionally narrow: it does not replace Pi's baseline harness policy and it does not try to become a second general-purpose prompt framework.

What it does

Every model receives one shared harness-core append layer with:

• output_contract
• scope_discipline
• tool_discipline
• dependency_checks
• verification_contract
• user_updates_spec
• safety_boundary

On top of that, the package targets two model families used inside Pi:

OpenAI GPT-5

• gpt-5* → GPT-5 family baseline layer
• gpt-5.*-codex → adds Codex-line coding corrections
• gpt-5.4* → adds GPT-5.4 execution/follow-through delta
• exact selected model gpt-5.4 → forces Responses API text.verbosity = "low" at runtime via before_provider_request
• gpt-5.3-codex → adds exact-model compact answer-shape / ambiguity delta

Anthropic Claude

• *claude* (any id containing opus, sonnet, or haiku) → Claude family baseline + coding-agent layer

Layer composition is additive. For example:

• mistral-large → HARNESS_CORE
• gpt-5.4 → HARNESS_CORE + GPT5_FAMILY + GPT54
• gpt-5.4-codex → HARNESS_CORE + GPT5_FAMILY + GPT5_CODEX + GPT54
• gpt-5.3-codex → HARNESS_CORE + GPT5_FAMILY + GPT5_CODEX + GPT53_CODEX
• claude-sonnet-4-5 → HARNESS_CORE + CLAUDE_FAMILY + CLAUDE_CODING_AGENT

Each layer is appended once via a unique marker, so repeated turns or partial prompt reuse stay idempotent.

Install

From npm

After publishing:

pi install npm:pi-per-model-prompt

From a local checkout

pi install /path/to/pi-per-model-prompt

Temporary loading during development

pi --no-extensions -e /path/to/pi-per-model-prompt/index.ts

Package layout

index.ts                                   # package entry declared in package.json -> pi.extensions
src/index.ts                               # extension implementation; registers before_agent_start + before_provider_request hooks
src/model-identity.ts                      # model id parser (gpt-5*, claude-*)
src/resolve.ts                             # layer resolution by family/version/tags
src/prompt.ts                              # prompt composition helpers
src/layers/base.ts                         # all-model harness-core append layer
src/layers/openai/gpt5/family.ts           # GPT-5 family baseline
src/layers/openai/gpt5/codex.ts            # GPT-5 Codex line layer
src/layers/openai/gpt5/gpt-5.4.ts         # GPT-5.4 delta
src/layers/openai/gpt5/gpt-5.3-codex.ts   # GPT-5.3-Codex delta
src/layers/anthropic/claude/family.ts      # Claude family baseline
src/layers/anthropic/claude/coding-agent.ts # Claude coding-agent layer
test/*.test.ts                             # coverage for parsing, composition, resolution, extension hook

The package uses a pi manifest in package.json:

{
  "keywords": ["pi-package"],
  "pi": {
    "extensions": ["./index.ts"]
  }
}

This matches Pi's package-loading rules from docs/packages.md and docs/extensions.md.

Development

npm install
npm test

Optional packaging check:

npm pack --dry-run

Design guard rails

• Keep the shared harness-core append layer stable, minimal, and model-agnostic.
• Keep family and exact-model rules evidence-driven and narrower than the shared core.
• Prefer additive layers over branching prompt trees.
• Keep exact-model deltas narrow and auditable.

See docs/architecture.md for maintenance guidance.

License

MIT