Met twice on 2026-10-25: the builder of #48 exited on a refused read of
the gate's source and crash-looped, and its new reasks bucket would have
done the same. A grant reaches the bus with a delivery, so a refusal or a
timeout at start is often only a grant not there yet; exiting for it
stopped the whole part until a hand step on the bus.
Every startup open in the parts is now essential or optional. Essential
ones (a part's own state and the input it exists for) still stop the
start, with an error naming the bucket and its grant. Optional ones are
said and left: watches the bus refuses too. The builder builds trunk keys
without the gate's source, which it opens again at the next candidate
that asks a trunk head; toolchains and previews open again at their next
event, as a missing bucket did. builder_ask_again says that asking a
running step again builds it twice.
jschoubben
20027e53ff