diff --git a/CLAUDE.md b/CLAUDE.md
index c741088d..769095c4 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -45,7 +45,10 @@
 
 ### What's In Progress
 - User preferences (export format default)
-- Deployment to Railway/Render
+
+### Deployment
+- **Production:** Railway (app.patherly.com / api.patherly.com)
+- **PR Environments:** Enabled - auto-created for each pull request
 
 ---
 
@@ -557,6 +560,43 @@ const response = await api.get('/api/v1/trees')
 
 ---
 
+## Railway Deployment
+
+### Production
+- **Frontend:** https://app.patherly.com
+- **Backend:** https://api.patherly.com
+- **Database:** Railway-managed PostgreSQL
+- Deploys automatically on push to `main`
+
+### PR Environments
+Railway creates isolated preview environments for each pull request.
+
+**Workflow:**
+1. Create feature branch: `git checkout -b feature/my-feature`
+2. Make changes, commit, push to origin
+3. Open Pull Request on GitHub
+4. Railway auto-creates preview environment (backend + frontend + DB)
+5. **Generate domains manually** in Railway dashboard:
+   - Switch to the PR environment
+   - Click on each service → Settings → Networking → Generate Domain
+6. **Set `VITE_API_URL`** on frontend service to point to the PR backend URL
+7. Redeploy frontend if needed
+8. Test at preview URLs
+9. Merge PR → auto-deploys to production
+10. Railway cleans up PR environment after merge
+
+**Environment Variables:**
+- PR environments inherit from `production` base environment
+- `REQUIRE_INVITE_CODE=true` is inherited (create invite codes in PR DB if needed)
+- `DATABASE_URL` is auto-provided for isolated PR database
+
+**Notes:**
+- Each PR gets a fresh database - no existing users/trees
+- Migrations run automatically via `releaseCommand`
+- Domains must be generated manually for each PR service
+
+---
+
 ## Contact
 
 **Primary User:** Michael Chihlas