ReadonlyappThe Pigeon upload session the process is in (UFS-<uuid>-<n>,
pigeonSessionId), read once for the request: its sent and completed
events name the same one.
ReadonlyrequestThe request's request_id.
ReadonlyrequestThe request's reason (cold_start).
ReadonlytrayThe request's tray_session_id: the process's tray session.
The stories tray's request, as its events name it: the request's own ids and reason.