ci / rust (push) Failing after 6m5s
`BrokerHandle::resolve_attach` queued ResolveAttach frames with `out_tx.send().await`. While the registry was disconnected nothing drained the bounded channel, so after 64 queued frames every caller blocked on the send — HTTP `/api/attach/:id` requests for peer sessions hung instead of erroring. Track link state with an `AtomicBool` the registry-client flips on connect / disconnect: `resolve_attach` returns `NoControlLink` immediately while down, and uses a non-blocking `try_send` so a back-pressured-but-connected channel can't block either. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>