A read a person started now runs as interactive work of their account, and
the document jobs as background work of theirs, so the reader's queue can
order and cap them. When the reader is busy or stopped before it answered,
a lab scan, label read or document read fails with aiRuns.readerBusy (503,
nothing read or charged) instead of a misleading unreadable-file error, and
the index and summary jobs throw so the queue runs them again rather than
recording an outcome about the document.