_devices was a plain Dictionary cleared and refilled in place by InitializeAsync /
ShutdownAsync while the retained poll engine, the fixed-tree and alarm loops and the
actor's health tick enumerated it ("Collection was modified"). It is now built whole and
published by reference swap, and a release swaps it out to empty before tearing it down.
Lane A's runtime overlaps lifecycle calls, so the driver now tolerates both shapes:
- a lifecycle generation is bumped by every Initialize/Shutdown; an initialise that finds
itself superseded (abandoned by the runtime, then a shutdown ran) publishes nothing,
starts no loops, writes no health and throws OperationCanceledException;
- a shutdown overlapping another (dispose beside a still-running shutdown) waits for the
first's teardown via a release tail instead of returning on an empty table;
- released devices are Retired: EnsureConnectedAsync refuses to reconnect them, and a
connect that completes after retirement disposes what it opened. Clients are disposed
under the device ConnectGate (bounded).
Refs #740
Claude-Session: https://claude.ai/code/session_01Ub9hGmYLQvn9XETzw7CMsT
Joseph Doherty
a32894e93b