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

Applicable 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

- **New project from scratch**: **REQUIRED** alternative - Use `humaninloop:authoring-constitution` directly
- **Codebase analysis not completed**: **REQUIRED** prerequisite - Run `humaninloop:analysis-codebase` first
- **Project too small for formal governance**: Single-file scripts, prototypes do not need constitutions
- **Validating existing constitution**: **OPTIONAL** - Use `humaninloop:validation-constitution`

## Prerequisites

**REQUIRED:** This skill extends `humaninloop:authoring-constitution`. Prerequisites for 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 `huma