Optionaldeps: DiagnosticsDepsProbes every target's current slot, recording latency and health into a HealthMonitor so the freshness ranking is identical to the pool's. An endpoint that throws (offline / errored) is flagged ok:false with slot null and never ranked.
Point-in-time verdict on a transaction. No polling: it inspects the current signature status and current block height once.
Order matters — a status check wins over the expiry bound, because a tx can land exactly at the deadline block (same precedence as ConfirmationTracker).