AI Multi-Platform Chat Application

I’m building a real-time chatting solution that works smoothly on both Android and the web and I need a developer who can take it from concept to a polished release. The centerpiece of the product is an AI layer that will:

• run a customer-service chatbot inside every conversation,
• offer on-the-fly language translation so users can talk freely in their native tongue, and
• generate concise message summaries when a thread gets lengthy.

Users will sign in with a simple email-based authentication flow; no social or guest options are planned for the first version.

You are free to recommend the stack, though I expect something modern that keeps one core code-base where possible (Flutter, React + React Native, or similar) and a scalable back-end (Firebase, Supabase, Node, etc.). Whichever route you choose, please outline:

1. How you plan to wire the AI features—whether that’s OpenAI, a self-hosted model, or another service—and how you will manage latency and cost.
2. The architecture for real-time messaging, push notifications, and offline caching.
3. A phased timeline culminating in tested Android APK and web deployment, source code, and a brief hand-off guide.

Clean, maintainable code and clear documentation are must-haves; unit tests around the AI utilities will be an advantage. If this scope excites you, let me know how you would tackle it and link to any similar chat or AI projects you have shipped.