Posted down thread, but worth posting as a comment too.

I know Simon follows this "Issue First" style of work in his projects, with a strong requirement for passing tests to be included.

It's been a best practice for a long time. I really enjoyed this when I read it ~10 years ago, and it still stands the test of time:

https://rfc.zeromq.org/spec/42/#24-development-process

The rationale was articulated clearly in:

https://hintjens.gitbooks.io/social-architecture/content/cha...

If you have time, do yourself a favour and read the whole lot. And then liberally copy parts of C4 into your own process. I have advocated for many components of it, in many contexts, at $employer, and will continue to do so.