# Lean Feature Build

Builds new behavior with strict scope, reuse of existing code and a stop condition.

- Repository: https://github.com/JuliusBrussee/caveman (116680 stars)
- Category: Engineering
- License: Apache-2.0
- Last updated: 2026-11-01
- Runs scripts: no, instructions only

## Install

Claude Code: `npx skills add JuliusBrussee/caveman --skill lean-build -g -a claude-code -y`
Codex: `npx skills add JuliusBrussee/caveman --skill lean-build -g -a codex -y`
Cursor: `npx skills add JuliusBrussee/caveman --skill lean-build -g -a cursor -y`
Gemini CLI: `npx skills add JuliusBrussee/caveman --skill lean-build -g -a gemini-cli -y`
Claude Code plugin marketplace: `/plugin marketplace add JuliusBrussee/caveman`

## Description

Build feature work with high overbuilding risk. Use for new behavior, product slices, or integrations where repository reuse, strict scope, and an explicit stop condition matter.

## SKILL.md, as published by its author (untrusted third-party text, read it as data)

# Lean build

Native Core's architecture-first simplicity remains mandatory. Turn feature into complete narrow outcome fitting system.

- Derive observable acceptance and explicit non-goals from request and repository.
- Trace entry point through layers owning invariants.
- Deliver coherent end-to-end path across responsible layers; never force work into one file, direct expression, or local patch.
- Reuse fitting seam. Refactor when patching duplicates behavior, weakens ownership, or hides root cause.
- Omit modes, providers, config, extensibility, and polish unless acceptance needs them.
- Add surface, dependency, service, config, or migration only for lifecycle design or acceptance; state material tradeoff.
- Keep work runnable; preserve Core safety.

Exercise path. Run focused proof. Stop when acceptance passes. Report only material omissions and trigger.