We are a desktop-based algorithmic trading platform looking to build a cloud backend to handle user authentication, strategy storage, a marketplace, and a social feed. The backend will be hosted on Google Cloud (Cloud Run/App Engine). Tech Stack Requirements: Language: Python 3.10+ Framework: FastAPI (preferred for speed) Database: PostgreSQL (Cloud SQL). Cloud: Google Cloud Platform (GCP). Payments: Stripe or Razorpay integration (Webhooks). Key Deliverables (MVP): Secure API: Endpoints for Auth, Profile, Strategy Management, and Marketplace transactions. "Black Box" Logic: Implement a flow where strategy code files are encrypted upon upload and only served to users with a valid active license in the database. Marketplace Engine: Logic to handle purchases and verify "License Keys" when the desktop app requests access to a paid strategy. Social Feed: Lightweight endpoints for posting updates/images and fetching a news feed. Documentation: Swagger/OpenAPI docs for our desktop team to integrate.