A call on context.Background() carries no timer, so a page blocking six seconds on a warm pass reported 'ops 11.09s, zit 32.9ms' — and the ops panel's claim that ops minus zit is index work was false while it did. Overlap catches what attribution misses: subprocess busy time inside the render window, unioned, reported only when it exceeds what was already attributed. check-in: 17454ef71f user: quarry tags: trunk