# Lean Build (lean-build)

> Builds a feature as a complete, narrow path that fits the system, reusing existing seams and adding nothing acceptance does not need.

- Category: [Feature Development](https://www.myskills.tools/en/categories/feature-development/)
- Source: Community · Julius Brussee
- Repository: https://github.com/JuliusBrussee/caveman/tree/main/skills/lean-build (commit 82864c8)
- SKILL.md: https://github.com/JuliusBrussee/caveman/blob/main/skills/lean-build/SKILL.md
- Install command: `npx skills add JuliusBrussee/caveman --skill lean-build`
- License: Apache-2.0
- Compatible with: Claude Code, Codex, Gemini CLI
- Permissions: read-repo ✓, write-files ✓, shell ✓, network ✗
- Status: Scan passed
- A rule scan cannot catch every risk. Read this skill's SKILL.md and check its permissions before installing.

## Core rule

Omit modes, providers, config, extensibility and polish unless acceptance needs them.

## Execution Phases

1. **Define acceptance** — Derive observable acceptance criteria and explicit non-goals from the request and repository.
2. **Trace the layers** — Trace from the entry point through the layers that own invariants and find the seam to reuse.
3. **Deliver end to end** — Build a coherent path across the responsible layers, never forcing it into one file or local patch; refactor when patching duplicates behavior or hides root cause.
4. **Prove and stop** — Exercise the path, run a focused proof, stop when acceptance passes, and report only material omissions.

## Permissions (summarised from SKILL.md)

| Capability | Needed | Details |
|---|---|---|
| File writes | Required | Edits code across the layers responsible for the behavior, refactoring where needed. |
| Command execution | Required | Runs a focused proof that acceptance passes. |
| Network outbound | Not required | The skill does not mention network access. |

## SKILL.md frontmatter (YAML)

```yaml
---
name: lean-build
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.
---
```

Home: https://www.myskills.tools/en/ · URL: https://www.myskills.tools/en/skills/lean-build/