chore: add gstack skill routing rules to CLAUDE.md

CLAUDE.md

@@ -273,9 +273,47 @@ docker-compose exec web npx prisma migrate deploy  # Run migrations in container
 - Requires external PostgreSQL database (Vercel Postgres, Supabase, etc.)
 - Redis is optional
 
-## Additional Resources
-
-- README.md - Detailed setup and feature overview
-- DOCKER_SETUP.md - Complete Docker deployment guide
-- prisma/schema.prisma - Database schema and relationships
-- env.example - Environment variable template
+## Additional Resources
+
+- README.md - Detailed setup and feature overview
+- DOCKER_SETUP.md - Complete Docker deployment guide
+- prisma/schema.prisma - Database schema and relationships
+- env.example - Environment variable template
+
+## gstack (REQUIRED — global install)
+
+Before doing any AI-assisted work in this repo, verify gstack is installed globally:
+
+```bash
+test -d ~/.claude/skills/gstack/bin && echo "GSTACK_OK" || echo "GSTACK_MISSING"
+```
+
+If `GSTACK_MISSING`: stop and install it:
+
+```bash
+git clone --depth 1 https://github.com/garrytan/gstack.git ~/.claude/skills/gstack
+cd ~/.claude/skills/gstack && ./setup --team
+```
+
+After install, use gstack skills where appropriate, especially `/browse`, `/review`, `/investigate`, `/qa`, `/ship`, and `/cso`.
+Use `~/.claude/skills/gstack/...` for gstack file paths because this repo does not vendor the pack locally.
+
+## Skill routing
+
+When the user's request matches an available skill, ALWAYS invoke it using the Skill
+tool as your FIRST action. Do NOT answer directly, do NOT use other tools first.
+The skill has specialized workflows that produce better results than ad-hoc answers.
+
+Key routing rules:
+- Product ideas, "is this worth building", brainstorming → invoke office-hours
+- Bugs, errors, "why is this broken", 500 errors → invoke investigate
+- Ship, deploy, push, create PR → invoke ship
+- QA, test the site, find bugs → invoke qa
+- Code review, check my diff → invoke review
+- Update docs after shipping → invoke document-release
+- Weekly retro → invoke retro
+- Design system, brand → invoke design-consultation
+- Visual audit, design polish → invoke design-review
+- Architecture review → invoke plan-eng-review
+- Save progress, checkpoint, resume → invoke checkpoint
+- Code quality, health check → invoke health