brownfield-constitution

# Brownfield Constitution Authoring

## Overview

Write project constitutions for **existing codebases** using the **Essential Floor + Emergent Ceiling** approach. This skill extends `humaninloop:authoring-constitution` with brownfield-specific guidance that respects existing patterns while establishing governance.

The core insight: existing codebases have implicit conventions worth preserving (Emergent Ceiling) but may lack foundational governance in critical areas (Essential Floor). This skill helps codify both.

## When to Use

Use this skill when:

- Creating a constitution for an **existing codebase** (brownfield project)
- The codebase has existing patterns, conventions, or architecture worth preserving
- You need to establish governance without disrupting working code
- The user mentions "brownfield", "existing codebase", or "legacy project"
- Codifying implicit conventions into explicit, enforceable principles

## When NOT to Use

Do NOT use this skill when:

- Starting a **new project from scratch** → use `humaninloop:authoring-constitution` directly
- **Codebase analysis has not been completed** → run `humaninloop:analysis-codebase` first
- The project is **too small to need formal governance** (single-file scripts, prototypes)
- You only need to **validate an existing constitution** → use `humaninloop:validation-constitution`

## Prerequisites

**REQUIRED:** This skill extends `humaninloop:authoring-constitution`. Before using brownfield mode:

1. **Understand core principles**: Read `humaninloop:authoring-constitution` for the Three-Part Principle Rule (Enforcement, Testability, Rationale)
2. **Know RFC 2119 keywords**: See RFC-2119-KEYWORDS.md in `humaninloop:authoring-constitution`
3. **Understand SYNC IMPACT format**: See SYNC-IMPACT-FORMAT.md in `humaninloop:authoring-constitution`
4. **Run codebase analysis**: Execute `humaninloop:analysis-codebase` to understand existing patterns

Brownfield constitutions follow all rules from `humaninloop:authori