refactoring

# Refactoring ## When to Use Activate this skill when improving code structure without changing external behavior. Use it for extracting utilities, reducing duplication, improving naming, or simplifying complex logic. ## Instructions 1. **Identify the smell**: Name the specific code smell (duplication, long method, feature envy, magic values, etc.). 2. **Plan the refactoring**: - List all files that will be affected. - Verify no external behavior will change (same API endpoints, same UI rendering). - Check if tests exist for the affected code (if not, consider writing tests first). 3. **Execute in small steps**: - Make one change at a time. - Verify the app still works after each step. - Use git to commit each step separately for easy rollback. 4. **Common refactorings for this project**: - **Extract row mapper**: Both backends have identical `FranchiseRow` → `Franchise` mapping. Extract to `packages/shared`. - **Unify API client**: `lib/api.ts` in Next.js and SvelteKit are nearly identical. Extract shared logic. - **Extract validation**: Both backends validate required fields inline. Create a shared validation function. - **Constants for SQL**: Move SQL query strings to named constants for readability. 5. **Verify**: - Run both backends and test CRUD operations. - Run both frontends and verify all pages render correctly. - Check TypeScript compilation passes in strict mode. 6. **Legacy project policy**: Focus refactoring efforts on the active stack (NestJS/SvelteKit) only. Do not invest refactoring time in legacy projects (Express/Next.js) as they are in maintenance-only mode. Shared utilities in `packages/shared` may still be refactored since they serve both stacks. ## Examples **Before (duplicated in both backends):** ```typescript const franchise = { id: row.id, name: row.name, ownerName: row.owner_name, email: row.email, phone: row.phone, address: row.address, city: row.city, state: row.state, status: row.status, createdAt: row.created_at, updatedAt: row.updated_at, }; ``` **After (shared utility):** ```typescript // packages/shared/src/mappers.ts export function mapRowToFranchise(row: FranchiseRow): Franchise { return { id: row.id, name: row.name, ownerName: row.owner_name, email: row.email, phone: row.phone, address: row.address, city: row.city, state: row.state, status: row.status as FranchiseStatus, createdAt: row.created_at, updatedAt: row.updated_at, }; } ```