Flask Python Web AI Skill Guide (Claude)

Overview & Engine Architecture

Flask is a WSGI microframework: explicit application factories, blueprints, and a request/app context stack. Extensions (db, migrate, CSRF) are constructed once and bound with init_app(app). Production traffic runs under gunicorn (or similar)—never flask run / app.run(). Agents fail closed on missing SECRET_KEY / DATABASE_URL in prod, push app_context() only when configuring, and keep Celery/RQ workers out of the request path.