The watch started empty in each process, so it missed a run live at the
session's start, a heartbeat's run and one live across a rotation, and it
cost 3 reads a poll at about 1.85 s of daemon CPU each on Eureka's mind.
Now who holds the slot is read at the first line and once in 15 s; a run
that left has its closing read once. A failed read keeps what was last seen.
A run that opens and ends between two reads goes unnoticed; the next first
line still shows it.
Tests through production inbox::derive replace the ones that pinned the
watch; the first line's bound is now pinned to count the tails it brings.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
8a19825d1b