Observed

"Exactly where they left off" holds only at checkpoint (node/superstep) boundaries: in-node progress is lost on failure, and a resumed node re-executes from its beginning — every side effect before an interrupt or failure must be idempotent or it runs twice (the vendor's own interrupts page documents this constraint). Two open bugs narrow it further, re-verified open 2026-06-11: Command(resume=None) crashes the resume flow with UnboundLocalError (#7034, opened 2026-03-05), and the sync checkpoint path caches ERROR/INTERRUPT writes that the async path guards against (#7015, opened 2026-03-04), so recovery behavior differs by execution path.