RunRecovered

A run continued the incomplete execution at fromCheckpoint. takenOverFrom is the run id of another run whose claim on the thread had expired, unreleased, and which this run's claim replaced: a takeover, so that run may still have been executing. It can equal this run's own id, when a caller reuses a RunId (RunConfig.withRunId): still a takeover of a separate, earlier run. None when the thread was free, and when the replaced claim was another tenant's or recorded no tenant: the log is the owner's, so it never names another tenant's run (RunClaim.takenOverFrom). A log written before the field existed reads as None.