> the preferred form of the work to making modifications to it
Implies what you point to when you want to know where to make changes.
That wouldn't be a prompt - you might use a prompt to make changes, but the thing you're making changes to, certainly at present, is your java/python/rust++ /whatever codebase.
Lots of projects, even fully vibecodes ones, don't push and include prompts in their repos. But they all push the java code (sticking with java as an example for the sake of argument).
I can't imagine that working on a project where the java code is omitted, and people make changes to the software just by editing the prompts would go well. It's an interesting thought experiment, but I think you'd find it very hard to work on any kind of team where that was the practice.
Where do I point to when I want to know this? On a large and mostly LLM-generated codebase, I might dig through the code myself to find what needs to be changed where, but I would probably prefer to ask an LLM to do this.
Now if I had access to all previous prompts that were used in generating the codebase, it might very well be the case that I would prefer to work by changing those prompts and generating the whole thing again. In that case, the LLMs would basically turn into a compiler and the prompts would indeed become the new "source code". This is clearly not (yet?) a common approach to software development, but I wonder if it may become. Or should.
If one uses LLMs to generate the code, and others need LLMs to read the code, isn't this awkwardly close to someone publishing only compiled binaries and others then having to reverse-engineer these binaries in order to know where and how to patch them? Maybe the handicap is less grave, as the difference in strength of LLMs understanding code vs writing them isn't as huge as of decompilers decompiling vs compilers compiling code - but I think this difference still exists. It's still an advantage to have knowledge of the "secret" prompts that were used in generating the code.