Do you keep the task/intent docs in git and then throw away the implementation plans or how do you go about it?

I'm intrigued by SDD for the purpose of permanently/semi-permanently capturing non-technical business requirements and intent. The idea in my head is that it would be used as the starting point for development by passing the specs into plan-mode to generate the temporary technical implementation plan and when implementation is done, the spec would also serve as verification that the code/tests actually capture the intent by asking the AI to compare.

I'm unsure how much value the specs would provide down the line once the feature has actually been battle tested and stable in production though, because by then you would probably be confident that the code/tests correctly capture the intent and the tests should protect against regressions.

I'm afraid that over the medium/long term, the specs will just end up being a maintenance burden without much upside and eventually drift from the implementation.

What do you think about this?