[deanclatworthy]

I understand what you are saying but I don't agree. As I wrote in a parent comment, should you want to change one thing, adjust the specification with the developers, agree with the stakeholders, implement. Done. This is just a spec to follow and reference.

[gomox]

Can you point to a successful commercial product built in this manner?

[henrikeh]

Not OP, but I’m not really getting what you are asking for?

[gomox]

As in, a commercial software product where a specification is maintained in parallel with the actual product.

[henrikeh]

Since you say “commercial” software I’m confused. Would that exclude medical software, aerospace software?

If what you are getting at is that it is not widely used/not used in anything “successful” and thus just a pipe dream, then I understand your concern. But that doesn’t mean it can’t be a useful strategy for some fields nor that it couldn’t produce more reliable systems.

[gomox]

I wouldn't exclude anything, but if the only examples of this are those kinds of highly immutable, mission critical software I think that would speak volumes about the practicality of maintaining a spec (the approach OP was pitching).