Venue & Catering Management SaaS Master Technical Specification (Developer Edition) 1. Product Overview A multi-tenant SaaS platform for venues and caterers covering lead management, booking calendars, BEO-driven operations, contracts, invoices with statement-based accounting, food costing, vendor payments, Google Calendar sync, and a full Android mobile app. 2. Core Principles 1 Multi-tenant data isolation 2 Event is the anchor entity 3 BEO defines scope and operations 4 Contract locks financial snapshot 5 Invoices are append-only 6 Statement explains financial position 7 Calendar controls availability only 8 Clients never see internal costs 3. Technology Stack 1 Backend: Python, Django, Django REST Framework 2 Database: PostgreSQL 3 Frontend (Web): Django templates (Phase 1) 4 Mobile: Flutter (Android first) 5 Calendar UI: FullCalendar.js 6 Auth: JWT + Django Auth 7 Notifications: Firebase Cloud Messaging 8 Google Calendar: OAuth 2.0 4. Core Modules 1 Accounts, Users, Venues, Venue Spaces 6 Contracts & Amendments 7 Invoices, Payments, Statements 8 Food Costing & Vendor Payments 9 Google Calendar 2-way Sync 10 Android Mobile App 5. Financial Architecture Invoices request money and are never edited after issuance. Statements are calculated summaries showing total contract value, invoices, payments, and balance due. BEO changes after signing generate contract amendments and adjustment invoices only. 6. Calendar & Google Sync The calendar supports soft holds, tentative bookings, and confirmed events. Google Calendar sync is two-way for availability only, with sanitized titles and no client data. 7. Mobile App The Android app (Flutter) consumes the same APIs as the web app and provides calendar access, event details, BEO views, invoices, statements, and push notifications. 8. Phased Delivery 1 Phase 1: Core models, calendar, BEO, contracts, deposit invoices, statements 2 Phase 2: Payment plans, Google Calendar sync, vendor bills 3 Phase 3: Full accounting, reporting, mobile enhancements