Foundation Skill

Establish technical foundation before writing PRDs. Proactively suggests best practices for the chosen stack.

When to use: Greenfield projects, or when starting a major new component. PRD skill will suggest this automatically if system-context is empty and no tech-stack.md exists.

Output

• .claude/rules/tech-stack.md — rules for Claude to follow (auto-loaded)
• docs/system-context.md — updated with Tech Stack section

ADRs are created separately via /sdlc-toolkit:adr if the user wants detailed documentation.

Instructions

Phase 1: Language & Scale

1. Check if .claude/rules/tech-stack.md already exists — if yes, ask if user wants to update or skip
2. Read docs/system-context.md if it exists — understand current state
3. Ask the user:
   • What language/framework? (e.g., FastAPI, Django, Express, Go, Spring Boot)
   • Estimated scale? How many endpoints/features are planned?
     • < 5 endpoints → suggest MVP structure (simple, flat)
     • > 5 endpoints → suggest Scalable structure (DDD-lite, bounded contexts)

Phase 2: Project Structure (CRITICAL)

4. Based on language + scale, show the CONCRETE folder structure from templates/project-structures.md
5. Explain WHY this structure is recommended:
   • Separation of concerns
   • Testability (tests next to code)
   • Scalability path
6. IMPORTANT: Explain the "tests next to code" rule:
   • Unit tests live INSIDE each module: users/tests/test_service.py
   • Integration/E2E tests live in root tests/ folder
   • NEVER dump all tests into a single tests/ folder
7. Confirm or adjust the structure with the user

Phase 3: Tech Stack Decisions

8. Based on the chosen language/framework, PROACTIVELY SUGGEST a complete stack. Use templates/tech-stack-presets.md as reference:

   Stack	Suggested Preset
   FastAPI	SQLModel, pytest-asyncio, Pydantic v2, Alembic
   Django	Django ORM, pytest-django, DRF
   Express	Prisma or TypeORM, Jest, Zod
   Go	sqlc or GORM, go test, chi/gin
   Spring Boot	JPA/Hibernate, JUnit 5, Flyway

9. Walk through each category, confirming or adjusting:

   • Database — type, dev/prod differences
   • ORM/Data Access — ORM vs raw SQL, migrations
   • API Style — REST/GraphQL, versioning
   • Authentication — strategy (JWT, sessions, OAuth)
   • Testing — framework, coverage targets
   • Deployment — target environment (Docker, serverless, etc.)

Phase 4: Generate Output

10. Create .claude/rules/tech-stack.md using templates/tech-stack-rules.md
    • Include ALL decided rules
    • Include project structure rules
    • Include test location rules
11. Update docs/system-context.md:
    • Add "Tech Stack" section at the top
    • If file doesn't exist, create it with Tech Stack section
12. Offer to create ADRs for major decisions via /sdlc-toolkit:adr

Important

• Be proactive: Don't just ask questions — SUGGEST solutions based on the stack
• Show concrete examples: Always show actual folder structures, not abstract descriptions
• Explain trade-offs: Help user understand MVP vs Scalable choice
• Focus on rules that matter: Only include rules that affect how Claude writes code
• The goal is to prevent technical debt by making decisions explicit BEFORE development starts

Supporting files

• templates/tech-stack-rules.md — Template for .claude/rules/
• templates/tech-stack-presets.md — Presets for popular stacks
• templates/project-structures.md — MVP and Scalable folder structures