Installing a package ends with the package's root being recycled: the hub is torn down so the one that comes back binds the package's own configuration instead of the placeholder it was created with. That is worth doing when the install rebuilt the root's type — and only then.

It ran unconditionally. Measured on a delivery run of 2026-09-08: one package logged 0 written, 21 unchanged and recycled its root anyway, and another was recycled twice in one bake. Nothing could come of those teardowns — no type had been rebuilt, so the hub that came back bound exactly what the old one already had.

They were not free. Each teardown cut off the correlated work in flight beneath the root — the root's own background reconcile — which the shutdown could not answer. It was force-cancelled at the shutdown's two-second window and reached the caller as "the hub was disposed before the response arrived".

What changed

The recycle now runs only when the install wrote something. That is the same condition the two recompile waves on either side of it already used, and the inconsistency was the bug: the waves knew an install that changed nothing has nothing to recompile, while the teardown between them did not.

And the log line stopped over-promising

It used to end "Work in flight beneath this root is answered by the teardown, not abandoned." That was measurably untrue — pending work was force-cancelled at the window, not answered — and a diagnostic asserting a guarantee the code does not keep is worse than one that says nothing, because it sends the next reader looking for a different cause. It now says what actually happens: work gets the shutdown window, and anything still pending at that bound is cancelled and surfaces to whoever issued it.

What this does not fix

An install that did write still recycles a root whose background pipeline may be issuing requests, and a hub that keeps accepting new work while it is shutting down is a separate defect. What is gone is the class where the teardown could accomplish nothing — removed by making the recycle agree with its neighbours, not by widening any window.