Backend (FastAPI):
- Core configuration and database setup
- SQLAlchemy models for all 17 tables (users, projects, fittings, phases, atoms, datasets, calculations, parameters, constraints, files, history)
- Pydantic schemas for request/response validation
- Service layer wrapping original pdfGUI logic unchanged:
  - FittingService (refinement workflows)
  - StructureService (crystal structure operations)
  - DatasetService (PDF data handling)
  - ConstraintService (formula parsing/evaluation)
  - FileService (upload/parsing)
  - AuthService (JWT + bcrypt authentication)
- REST API endpoints for all CRUD operations
- Main FastAPI application with CORS

Frontend (React):
- TypeScript types for JSON-driven forms and charts
- DynamicForm component with Zod validation
- Wizard component for multi-step workflows
- PDFPlot component using Plotly
- JSON form schemas (fitting wizard)
- Chart template configurations
- API client service with auth interceptors
- Zustand auth store with persist
- React Router setup with protected routes

Tests:
- Pytest configuration with fixtures
- Numerical regression tests matching original pdfGUI:
  - Grid interpolation (15 decimal precision)
  - Constraint evaluation
  - Structure operations
  - Dataset operations
  - Project loading
- API endpoint tests

Documentation:
- Complete requirements gap analysis (10-pass review)
- 70% overall completion with clear path to 100%