Idempotent maintenance for the Database transport. Statements come from the operator call builder (plan 05), so
the claim path and the sweeper can never disagree about lease expiry; this class takes the sweep lock, sequences
the calls on the lock's own executor (never the shared provider, F8), repeats purges and reports counts. One
sweeper runs at a time across all instances (03 §7, F9).
Runs one pass. Returns {} when a pass is already running here or another instance holds the sweep lock;
a failed step reports -1. ExpireLeases is the number of deliveries the pass DEAD-LETTERED.
Idempotent maintenance for the Database transport. Statements come from the operator call builder (plan 05), so the claim path and the sweeper can never disagree about lease expiry; this class takes the sweep lock, sequences the calls on the lock's own executor (never the shared provider, F8), repeats purges and reports counts. One sweeper runs at a time across all instances (03 §7, F9).