A box is reused by slot (resource, field) after the composition, from what runs or the
have's slots; a have written before slots is reused within its module alone. Config
values are laid by mesh-sdk's one rule (never a default). The shadow answers the
newest candidate first and hands each answer as it lands, says when an answer starts,
every minute what it waits on, and when it ends, and fits an answer to the node's key.
Needs mesh-sdk fix/1126-seed-same (16b8d8a1).