# Trellis Before Dev

Discovers and injects project-specific coding guidelines from .trellis/spec/ before...

- Repository: https://github.com/mindfold-ai/Trellis (15078 stars)
- Category: Writing
- License: AGPL-3.0
- Last updated: 2026-09-29
- Runs scripts: no, instructions only

## Install

Claude Code: `npx skills add mindfold-ai/Trellis --skill trellis-before-dev -g -a claude-code -y`
Codex: `npx skills add mindfold-ai/Trellis --skill trellis-before-dev -g -a codex -y`
Cursor: `npx skills add mindfold-ai/Trellis --skill trellis-before-dev -g -a cursor -y`
Gemini CLI: `npx skills add mindfold-ai/Trellis --skill trellis-before-dev -g -a gemini-cli -y`

## Description

Discovers and injects project-specific coding guidelines from .trellis/spec/ before implementation begins. Reads spec indexes, pre-development checklists, and shared thinking guides for the target package. Use when starting a new coding task, before writing any code, switching to a different package, or needing to refresh project conventions and standards.

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

Read the relevant development guidelines before starting your task.

Execute these steps:

1. **Read current task artifacts**:
   - `prd.md` for requirements and acceptance criteria
   - `design.md` if present for technical design
   - `implement.md` if present for execution order and validation plan

2. **Discover packages and their spec layers**:
   ```bash
   python3 ./.trellis/scripts/get_context.py --mode packages
   ```

3. **Identify which specs apply** to your task based on:
   - Which package you're modifying (e.g., `cli/`, `docs-site/`)
   - What type of work (backend, frontend, unit-test, docs, etc.)
   - Any spec/research paths referenced by the task artifacts

4. **Read the spec index** for each relevant module:
   ```bash
   cat .trellis/spec/<package>/<layer>/index.md
   ```
   Follow the **"Pre-Development Checklist"** section in the index.

5. **Read the specific guideline files** listed in the Pre-Development Checklist that are relevant to your task. The index is NOT the goal, it points you to the actual guideline files (e.g., `error-handling.md`, `conventions.md`, `mock-strategies.md`). Read those files to understand the coding standards and patterns.

6. **Always read shared guides**:
   ```bash
   cat .trellis/spec/guides/index.md
   ```

7. **For a non-trivial task, state the change boundary before writing code.** Non-trivial means it touches more than one file, crosses a layer, changes a public interface, or edits code you did not just write. Write down:
   - the smallest behavior gap between what happens now and what should happen
   - where that behavior actually lives (not where it is easiest to intercept)
   - which files you expect to change, and why each one is necessary
   - what you are explicitly not doing in this task
   - if a local refactor is needed, how you will show it did not change behavior

   A small, well-scoped change does not need this, do it directly.

The rest: https://github.com/mindfold-ai/Trellis/blob/HEAD/.agents/skills/trellis-before-dev/SKILL.md