Generate CLAUDE.md Skill

Generate a production-quality CLAUDE.md for a project, following best practices. The output must be concise, universally applicable, and use progressive disclosure.

Critical Constraints

Claude Code's system prompt already uses ~50 instructions. Frontier models reliably follow ~150-200 total. This leaves ~100-150 for ALL CLAUDE.md files + skills + rules.

Therefore:

• Root CLAUDE.md MUST be under 80 lines (ideally 40-60)
• Every line MUST be universally applicable to all tasks in this project
• Task-specific instructions go into .claude/rules/ with path scoping
• Detailed docs go into docs/ referenced via @ imports

Process

Step 1: Analyze Project

Scan the project to detect:

1. Read package.json / requirements.txt / pyproject.toml / go.mod / Cargo.toml → Determine language, framework, dependencies
2. Read existing config files:
   • .eslintrc / ruff.toml / biome.json → Linter exists? (don't add style rules)
   • tsconfig.json / mypy.ini → Type checker config
   • jest.config / pytest.ini / vitest.config → Test framework
   • docker-compose.yml / Dockerfile → Infrastructure
   • .github/workflows/ → CI/CD
3. Scan directory structure:
   • Glob src/**/ → Identify architecture layers
   • Check for monorepo patterns (apps/, packages/, services/)
4. Read existing README.md if present → Project purpose
5. Read existing CLAUDE.md if present → What to preserve/improve

Step 2: Ask Clarifying Questions (max 5)

Ask ONLY what cannot be inferred from code. Use targeted questions:

1. Purpose: "What does this project do in one sentence?" (skip if README is clear)
2. Architecture decisions: "Any non-obvious architectural choices I should know?"
3. Key constraints: "Any MUST/MUST NOT rules the team follows?"
4. Workflow preferences: "Should Claude propose plans before coding, or go direct?"
5. What's special: "Anything unusual about this project that would surprise a new developer?"

Skip questions where the answer is obvious from code analysis.

Step 3: Generate CLAUDE.md

Follow the WHAT / WHY / HOW framework. Use the CLAUDE.md template.

Generation rules:

• MUST be under 80 lines
• MUST NOT include code style rules if a linter is configured
• MUST NOT include generic programming advice ("write clean code", "handle errors")
• MUST NOT include task-specific instructions (use rules/ for those)
• MUST use MUST / MUST NOT / NEVER for hard constraints (not "prefer" or "try to")
• MUST include exact, copy-paste-ready commands for build/test/lint
• MUST use @path/to/doc.md for detailed docs instead of inlining
• MUST NOT copy code snippets — use file:line references instead
• Prefer pointing Claude to WHERE info is, not duplicating it

Step 4: Generate Scoped Rules (if applicable)

If the project has distinct domains (API, frontend, infra), create scoped rules in .claude/rules/.

Use the scoped rule template.

Each rule file:

• MUST have paths: frontmatter with glob patterns
• MUST be under 30 lines
• MUST contain only instructions relevant to those file paths

Step 5: Validate

Run validation checklist:

• Total lines ≤ 80?
• No code style rules? (check: linter configured?)
• No generic advice? ("write clean code", "handle errors")
• No task-specific instructions? (belongs in rules/ or skills/)
• All commands are exact and runnable?
• Hard constraints use MUST/MUST NOT/NEVER?
• Detailed docs referenced via @ imports, not inlined?
• No copied code snippets? (use file:line refs)
• Would every instruction be useful for EVERY task in this project?

If validation fails, revise before saving.

Step 6: Save

• Save CLAUDE.md to project root
• Save .claude/rules/*.md if generated
• If CLAUDE.local.md doesn't exist, create a minimal one from the local template
• Report: line count, rules count, what was included/excluded and why

Anti-patterns to Avoid

Never include in CLAUDE.md:

• Generic advice (Claude already knows): "Write clean code", "Handle errors properly", "Follow SOLID"
• Code style rules (use linter + hook instead): indentation, quotes, trailing commas, line length
• Exhaustive docs (use @import): listing all API endpoints, all models, all components inline
• Task-specific instructions (use rules/): "When writing migrations, always...", "When creating React components..."
• Hotfix log (group and generalize): "NEVER use setTimeout for async (added 01/15 after bug)"

Supporting files

• templates/claude-md.md — CLAUDE.md template
• templates/claude-local-md.md — CLAUDE.local.md template
• templates/scoped-rule.md — Scoped rule template