One JSON line per transition: ticks and the exact remainder, digests of the rates, of the
transition's spikes, of the frame and of work RAM, the decision and the mask, macro and reward
events in order, the rank, and the boundary's slot saves, rollback and captures in the shape of
TraceBehaviour.boundaryActions and TraceOperational.captures. Off unless FLY_TRACE names a file.
Recorded inline in step_frame first, so the frame's extraction can be held to it.
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