Dudley's audit of the suspected ConnectionId(0) starvation: exhaustive
trace of the delivery path (bridge/mod.rs insert/lookup/send paths,
atlas plugin serve/drain, gen_queue coalescing) found NO sentinel or
default-value collision — ConnectionId doesn't even derive Default, and
every id path is a plain monotonic allocation with linear lookup. The
real gap was coverage: every existing window test used ConnectionId(1).
New connection_zero_window_delivery module replicates main.rs's actual
bootstrap (blocking first-accept -> BridgeResource -> accept loop) and
pins: the first-ever connection receives a district window; the exact
six-tile entry shape delivers all six to connection 0; connection 1
keeps working. 5/5 repeated runs, single- and parallel-threaded.
The live 'starvation' itself was client-side (pending responses never
re-requested on the tile path — separate fix in flight); these tests
stay as the server half's permanent pin.