Files
Per-driver counters surfaced via DriverHealth.Diagnostics for the driver-diagnostics RPC. New OpcUaClientDiagnostics tracks PublishRequestCount, NotificationCount, NotificationsPerSecond (5s-half-life EWMA), MissingPublishRequestCount, DroppedNotificationCount, SessionResetCount and LastReconnectUtcTicks via Interlocked on the hot path. DriverHealth gains an optional IReadOnlyDictionary<string,double>? Diagnostics parameter (defaulted null for back-compat with the seven other drivers' constructors). OpcUaClientDriver wires Session.Notification + Session.PublishError on connect and on reconnect-complete (recording a session-reset there); GetHealth snapshots the counters on every poll so the RPC sees fresh values without a tick source. Tests: 11 new OpcUaClientDiagnosticsTests cover counter increments, EWMA convergence, snapshot shape, GetHealth integration, and DriverHealth back-compat. Full OpcUaClient.Tests 115/115 green. Closes #276 Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>