CLAUDE.md

This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.

Project Overview

Agent Skills for Context Engineering — an open collection of 14 Agent Skills teaching context engineering principles for production AI agent systems. Skills are platform-agnostic (Claude Code, Cursor, GitHub Copilot, any Open Plugins-conformant tool).

Context engineering is the discipline of curating everything that enters a model's context window (system prompts, tool definitions, retrieved documents, message history, tool outputs) to maximize signal within limited attention budget.

Repository Structure

• skills/ — 14 skill directories, each containing a SKILL.md with YAML frontmatter (name, description) and optional references/ and scripts/ subdirectories
• examples/ — 5 complete demonstration projects (digital-brain-skill, llm-as-judge-skills, book-sft-pipeline, x-to-book-system, interleaved-thinking)
• docs/ — Research materials and reference documentation
• researcher/ — Research output examples
• template/SKILL.md — Canonical skill template (use when creating new skills)
• SKILL.md (root) — Collection-level metadata and skill map
• .claude-plugin/marketplace.json — Claude Code marketplace manifest (5 bundled plugins)
• .plugin/plugin.json — Open Plugins format manifest (v2.0.0)

Build & Test Commands

No top-level build system. Individual example projects have their own tooling:

examples/llm-as-judge-skills (TypeScript, Node >= 18)

cd examples/llm-as-judge-skills
npm install
npm run build        # tsc
npm test             # vitest (19 tests)
npm run lint         # eslint
npm run format       # prettier
npm run typecheck    # tsc --noEmit

examples/interleaved-thinking (Python >= 3.10)

cd examples/interleaved-thinking
pip install -e ".[dev]"
pytest               # pytest + pytest-asyncio
ruff check .         # linting (100 char line length)

examples/digital-brain-skill (Node.js)

cd examples/digital-brain-skill
npm run setup
npm run weekly-review
npm run content-ideas
npm run stale-contacts

Skill Authoring Rules

When creating or editing skills:

1. SKILL.md must stay under 500 lines — move detailed content to references/ directory
2. YAML frontmatter is required — must include name and description fields
3. Folder naming: lowercase with hyphens (e.g., context-fundamentals)
4. Write in third person — descriptions are injected into system prompts; inconsistent POV causes discovery issues
5. Platform-agnostic — no vendor-locked examples or platform-specific tool names without abstraction
6. Token-conscious — challenge each paragraph: "Does Claude really need this?" Assume advanced audience
7. Include a Gotchas section — experience-derived failure modes are the highest-signal content in any skill
8. Update root README.md when adding new skills
9. Update marketplace/plugin manifests when adding skills (.claude-plugin/marketplace.json, .plugin/plugin.json)

Plugin Architecture

All 14 skills are distributed as a single plugin (context-engineering) in the marketplace manifest. This avoids cache duplication — Claude Code caches each plugin's source directory separately, so multiple plugins pointing to source: "./" would each cache a full copy of the repo.

Progressive disclosure pattern: only skill names/descriptions load at startup; full content loads on activation.

Key Design Principles

• Context quality over quantity — attention scarcity and lost-in-middle phenomenon mean more context is not always better
• Sub-agents isolate context — they exist to manage attention budget, not simulate org roles
• Skills reference each other — use plain text skill names (not links) in Integration sections to avoid cross-directory reference issues
• Examples use Python pseudocode — conceptual demonstrations that work across environments, not production-ready implementations