Exactly. That is one of the core design rules in Keep the Why: if a change touches rationale, updating that rationale is part of the same change and should be reviewed in the same PR/MR as the code.

The repo is the source of truth, but Git alone does not prevent stale reasoning. The useful property is that code and rationale share the same lifecycle, review path and history.

Otherwise, as you say, it just becomes another artifact that was once correct.