[abkonsta]

New rocker, new lifter just in case.
Since I couldn't see anything wrong with the camshaft, I put the old one back in.
Put everything back together. 100% improvement - no knock, been driving it around for a couple of days, engine knock code has not come back... I think we're in the clear!

So, exactly as in ///Motivated's case, my top end knock (bad rocker) was occasionally setting off the detonation knock sensor.