H2: a Bad/null publish drops the deadband baseline and any status change
publishes, so a device that returns holding the identical value is no longer
swallowed by |new - old| < deadband (the #527 value-only-dedup trap).
Integration case drives a real drop/restore through a loopback relay.
Refs #741
Claude-Session: https://claude.ai/code/session_01Ub9hGmYLQvn9XETzw7CMsT
P3: a torn-down socket is re-dialled inside the gate (one attempt per backoff
window) instead of failing fast with 'Transport not connected' until the 90 s
comms-loss watchdog re-initialised the driver.
L3: ConnectAsync disposes the previous/failed TcpClient, DNS runs under the
per-op timeout, and the reconnect never sleeps inside the gate (the old
10-attempt backoff held it for ~81 s).
H9: an MBAP response with no PDU, or an exception PDU with no code, is a
TruncatedFrame desync rather than an IndexOutOfRangeException.
Refs #741
Claude-Session: https://claude.ai/code/session_01Ub9hGmYLQvn9XETzw7CMsT
Joseph Doherty