[csbartus]

I'm about to finish my first provably / likely correct software.

The concept, data, and behavioral models are all formal without using formal methods. Think category theory, normal forms and finite-state machines here.

The presentation layer / the visual mapping model is semi-formal using design systems. Think here a usual component library / design system with a closed API, aka tailor made components without styling props.

The rest, that small amount of hand-written code is tested with 100% code coverage.

The concept and behavioral models are created with visual diagram editors, the data model is generated. Think Stately.ai here, and the diagrams-as-code paradigm.

Any practicality in this?

Yes, it solves two major developer pain points: Code architecture and State management: https://2023.stateofjs.com/en-US/usage/#top_js_pain_points