C# & MySQL and Flutter App Developer: System Stabilization and Feature Integration

We have an internal appointment booking platform that manages schedules for our teams via a web application and a mobile application (developed in Flutter). The system uses a synchronized MySQL database setup (local and online). We need a skilled developer to address current instability and add critical new functionality. Scope of Work: Phase 1: Analysis & Stabilization Audit the existing codebase (PHP, Flutter, C#, MySQL) to identify the root causes of current flaws and instability. Implement fixes to ensure robust, error-free performance across both web and mobile platforms. Mobile Specific: Implement a reliable background notification service for the Flutter application to handle appointment reminders and updates. Phase 2: Invoicing & Quotation System Integration Design and develop a new module within the application to generate, manage, and track quotations and invoices. Ensure seamless data flow between the appointment booking logic and the new financial module. Requirements: Demonstrable experience with similar full-stack projects. Proficiency in our tech stack: PHP (Backend), Flutter (Mobile), C# (Potential legacy/API components), and MySQL. Specific Experience: Strong background in implementing background services/push notifications in Flutter (using Firebase Cloud Messaging, Isolates, or Workmanager) is essential. Strong database skills (MySQL). Portfolio examples showcasing clean, maintainable code. Application Instructions: In your proposal, please include: Examples of past work on system stabilization, Flutter background services/notifications, or invoicing features. Your initial assessment of how you would approach this project, particularly the notification service and database synchronization. Your estimated timeline and total project cost (fixed-price preferred). Apply tot his job