How do you start a new "big" project and keep it maintainable?

Developer here. I am pretty new to agentic coding. I have really enjoyed vibe coding web apps as personal tools, so nothing mission critical. Basically I have always just written a huge multi-page prompt, gave it to Claude code or Cursor and that's it.

Anyway, now at work a project just landed on my lap and my boss said I have to try and maximize AI usage just as an experiment and learning experience for the company.

So now I want to do this in a more maintainable way. I basically have my spec written down and I have a rough idea of what I want.

Is this a good way to approach it?

• Use boilerplate code as a starting point
• Write Claude.md for basic stuff
• Have conversation with Claude and try to figure out together all blind spots and questions related to my spec.
• Write comprehensive to-do list for Claude and update my spec for all the blind spots I might have missed.
• Start executing a couple of to-do list items at a time, review the code and write tests for everything. Focus on test driven development and commit at every possible point.
• Implement Claude or some other model to review pull requests

Any other ideas or tips for me? How often should I clear the history of the conversation to start fresh?

The application is not too mission critical, just a useful internal web application with a few users so that's why it's perfect for this experiment. One thing I am worried about is that the users are not technical people and I know they will come back with more feature requests or I have to go back and change something. Should I also have Claude write documentation so it's easier for it to go back and do refactoring?