How do you structure front end workflows before using AI tools?

I've been using AI tools to help with frontend development, but it's been pretty ad hoc so far, mostly generating components on demand without much structure.

I’d like to move toward a more traditional and sustainable workflow: - Start with UI/UX design - Create a design system from those designs - Implement components that are reusable across the app

Before even prompting an LLM to write code, I want to establish a solid foundation that makes the AI's output more consistent and maintainable.

What workflows, tools, or practices do you use to go from design to implementation in a way that scales?

Bonus points for open source solutions, but I’m open to any ideas, tools, scripts, design systems, or even just habits you've adopted that help keep things coherent.