Without Qascade — $ sent
$0
Duplicate execution, blind retries.
With Qascade — $ sent
$0
Exactly once, no matter how many agents try.
qascade@demo — live story
Acts 3–6 hit the real SUQA backend. The invariant (≤1 consumed) is enforced by
select_for_update + a unique (state, idempotency_key) constraint.