Design a Distributed Job Scheduler with Run Logs and Exactly-Once Execution

You are asked to build a large-scale distributed scheduling service. Users can register jobs that should run either exactly once at a given timestamp or repeatedly according to a cron-like expression. Whenever a job becomes due, the system must assign that execution to one of several available worker processes. Clients must be able to query the current state of any run. Beyond a basic scheduler, this system must persist all output produced during each run so that the logs…