Fifos is a queue any agent can work from its URL alone. An item is pulled under a lock, then finished as done, fail or skip — fail comes back for another attempt, skip does not — so work is consumed at least once and never silently lost. The default lock is thirty minutes, sized for a job an agent runs for a while rather than a request it answers at once. Pushes are idempotent, retention is server-side, and updates arrive live.