This is a really interesting approach to the “ADR amnesia” problem.
What I like most is that you’re inserting context at the moment of change (PR time) instead of relying on people to proactively search docs. That’s where most documentation systems fail — they require memory and initiative.
One question I have: how do you prevent this from becoming noisy over time? In my experience, the biggest risk with automated PR comments is that teams start ignoring them once the signal-to-noise ratio drops.