4d0d5d229d
SubscribeAsync left the SDK Subscription on the session (server-side when CreateAsync succeeded, item handlers attached, tracked by nothing) when CreateAsync/CreateItemsAsync threw, so the host's per-tick reconcile retry accumulated one live subscription per retry. Mirror the alarm path: detach the item handlers, bounded RemoveSubscriptionAsync, rethrow. Refs #743 Claude-Session: https://claude.ai/code/session_01Ub9hGmYLQvn9XETzw7CMsT