But that doesn't distinguish between "VC Alpha", which means early access, and "Programmer Alpha", which means basic functionality doesn't work.

(The inverse is "VC 1.0", which means pre-release but we had to meet a deadline, and "Programmer 1.0", which means it's the first stable version.)

> "Programmer 1.0", which means it's the first stable version

I thought "Programmer 1.0" is more like +Infinity and never ever reached? ;)

I don't understand, what set of programmers never (do/want to?) to reach 1.0? Are you referencing something like the Tex versioning scheme?

Conventionally 1.0 is just the inflection point where things are featureful and stable enough that you start making guarantees about the stability of whatever interface/contract/API/whatever that matter to the consumer of whatever you are building.

At least in the past a lot of useful (and actually 'finished') tools were forever at a some 0.x version, especially before semantic versioning got popular. I guess they just wanted some increasing version number but just '1, 2, 3, 4, 5, ...' looked too weird, so they went for '0.1, 0.2, 0.3, ...'.

As far as it can be ascertained, Vale has been in development for at least 3 years (2020).