your LLM prompt is, by definition, underspecified. the code is what describes the actual behaviour of the system, and there are known and understood ways to make that behaviour more robust, correct and resilient, that are independent of the domain the code is modelling, but consistent across different code bases. that's why I say writing code is its own domain.

as an analogy, an art museum couldn't paint their own paintings to hang up (or at least they would not be very good) but neither would monet or picasso have done a particularly good job at designing a space to let millions of people a year view their pictures. both skills are necessary to the overall product.