Joseph Doherty
a178d68b60
- TryAttachWorkerClientAndMarkReadyAsync returns SessionAttachOutcome and refuses a worker client that is already Faulted/Closed; the open discards it and fails OpenFailed. - MapWorkerEventsAsync calls ObserveWorkerTerminalState when its first readiness check fails, so a worker that dies between attach and the first pump read faults the session and the faulted sweep reaps it. - A caller-cancelled open rolls back, records no fault and rethrows the cancellation (gRPC Cancelled); an attach refused because the drain closed the session reports GatewayStopping. - docs/Sessions.md updated.