That's a great question, and has so many aspects to it. Quality control for OS dev, quality control for small apps built by users, quality control for SaaS software, quality control for desktop applications, and quality control for enterprise software all may have different needs and solutions.
I do think we are going to enter uncharted territory. I've seen even non-technical, or barely technical people, start to build apps or use AI agents to automate work. Quality control is going to become very important.
For my personal projects, I always start with a coding style guide to try to build clean code. For Haiku apps, this is mostly Haiku's coding style (though I loose the line length restrictions). Other types of projects will have their own requirements. For example on web apps I will define if I want to use an ORM or write manual SQL, I will instruct it not to write code that slams the database (i.e. select statements in a foreach over 100k objects), etc.
I also have general guidelines of "always choose proper/structurally sound decesion instead of prioritizing quick fixes or work arounds", etc.
Then I do a research phase. I look at other similar software to identify what I do and don't like, whats "the good, the bad, the ugly" about how each software implements a feature I am interested in, etc.
Then with all that I can come up with a plan, and use the LLM to implement against the plan.
I still manually test, but also can use the LLM to do larger stress tests. Hypothetically, if I was writing a new bit torrent app I could give the LLM a list of several hundred torrents and have it downloaded them all 80 times, while adjusting parameters such as bandwidth and concurrency limits, and doing checksums on all the files.
I've started to spin up a local AI which I will use for code reviews and "code to plan" reviews. "Code to plan" is my term for "did the LLM really execute against the plan? Or take shortcuts to just make it work? Or did it do something nonsense"
I've found that workflow produces pretty good results.
In the professional world, it's a little more invovled.