Design and process judgement for the core product line, most of it never written down.
Spends part of most weeks now in structured interview sessions he finds slightly uncomfortable, being asked to explain things he has done by feel for two decades. Otherwise still doing the job as normal — reviewing designs, answering questions from younger engineers who come to his desk rather than searching for an answer, because for most of his career there was nothing to search.
Being asked to articulate judgement calls he has never had to put into words before, and worrying that some of it genuinely cannot be captured in the time remaining.
Whether the retirement actually happens without a crisis six months later — not something he personally tracks, but something he is aware hangs on this.