Found by the H13 stress test (200 re-inits under a concurrent reader): a read
that resolved the device just before the table swap could cold-create a
runtime into the retired state after its teardown had disposed it (leaked
native handle / lease), and could hit a per-tag SemaphoreSlim the teardown had
disposed, which the generic catch reported as a comms fault (Degraded).
- DeviceState.Retire marks the state retired before disposing handles; each
handle is removed-then-disposed exactly once. A creator re-checks the flag
after its TryAdd (fenced, Dekker-paired with Retire) and disposes the orphan.
- A failure on a retired device is the teardown's doing: BadCommunicationError
for that one call, no evict, no health signal.
- Per-tag/RMW gates are no longer disposed (async-only waits hold no handle),
matching the ConnectGate rationale.
Refs #737
Claude-Session: https://claude.ai/code/session_01Ub9hGmYLQvn9XETzw7CMsT
Joseph Doherty
48b0173ae9