Hm; I guess when being in talks with a company using the language, assuming the pragmas idea I elaborated in a cousin comment, I'd then be asking questions like:
"Is your codebase any=default or any=forbidden? What percentage of it is any=allowed?" (Instead of the current:
"are you using JS, Go, or Rust?")
Notably, in my particular case, what you say is a problem is exactly why I want it: because when writing the PoC, I don't really know what I'm doing yet; and I want to only sketch it. Once I see the sketch and it looks like the general idea has some promise, I want to "grab the pen and start drawing" - i.e. start diving into the nitty-gritty dark corners of ugly interactions, corner cases, & stability, as a way of better understanding & exploring my domain/project/idea (specifically, using the compiler as a tool that is forcing me to do that, by asking me difficult questions). And I may want it graded in various areas of my codebase: some are super unimportant or still being explored, and I'm ok having them explicitly marked as "sketchy"; others are where I really care about extreme security, so want full prover power, and I want to know their exact boundaries too; finally, some are the "more or less know what I'm doing, but not life-critical" to bigger or lesser extent; notably with some small corners marked with an explicit "caution: here be dragons" `unsafe` (I mean, `any=allowed`) yellow tape.