Specs-as-history is rapidly becoming an antipattern as teams actually try to scale SDD. We're already putting guardrails in agents.md (non-normative in all caps), some teams are actually offboarding them - to Rally (which I find the height of hilarity).

Spec docs - at least in all the other things like this thing - aren't a living representation of truth, instead they are a collection of snapshots in time of feature deliverables. Layer 500 of these on top of each other and they quickly become not just useless but actively harmful. Archive them, compile them, whatever your plugin does, it still doesn't help. Nobody is going to pay for tokens just to keep the specs time-coherent, when the agent can just read the code.

Don't get me wrong, a spec is a useful bit of kit for development, just like Jira and Rally, but also like Jira and Rally they aren't the source of truth because there's already a better one which you just paid for.