Committed state of one runtime channel inside a Docket.Run.
version advances once per committed update barrier that wrote the channel
(write-based change tracking: equal values still bump). Value channels that
have never been written are absent from run.channels entirely, so their
stored version is always at least 1; :barrier channels may be stored at
version 0 while accumulating barrier_seen before the barrier first fires.
barrier_seen is used only by :barrier channels: the sorted list of
source node public IDs that completed since the barrier last fired.
Summary
Types
@type t() :: %Docket.Run.ChannelState{ barrier_seen: [String.t()], channel_id: String.t(), value: term(), version: non_neg_integer() }