the declared report shape — what this operation's landing tells the caller
Land this run: clean, or with the coded reason it failed, and with the run's structured result where the operation declares one. Lands at most once.
A refusal and a report are not alternatives. A paste that landed six parts and refused
two is a run that both succeeded and refused, and flattening that into one of the two is
exactly the ambiguous answer the house forbids.
Progress of this run, clamped into [0, 1]. Dropped once landed or cancelled.
The handle one run reports through. Both calls are void once the run is not current.