[tobias-tengler]

When the broker closes a consumer's channel or cancels the consumer while the connection stays up, the RabbitMQ transport never consumes from that queue again until the process restarts, and it logs nothing. A consumer timeout causes exactly this: before RabbitMQ 4.3 it closes the channel with 406 PRECONDITION_FAILED, and from 4.3 it sends basic.cancel and keeps the channel open. The client library never recovers channel-level losses, and the consumer manager only re-attached consumers after a connection event. Handlers still running on the lost channel also kept their token and kept retrying, and their acks were skipped silently.

This PR makes RabbitMQConsumerManager treat any channel shutdown or server-sent cancel that Mocha did not initiate itself as a lost consumer. It re-attaches the consumer on a fresh channel with backoff for as long as the registration is alive, and keeps retrying with an Error log while the queue is missing. Each channel now gets its own handler cancellation token, which is cancelled when that channel's consumer is lost. The periodic health check now also re-attaches registered consumers that are not attached. Lost consumers, re-attachment, and acks or nacks skipped because the channel is closed are now logged. Integration tests against a real broker cover both a closed channel and a cancelled consumer, the returned message being delivered again first, and disposal not causing a re-attach.

[github-actions]

Patch coverage

87.2% of changed lines covered (383/439)

File	Covered	Changed	Patch %
…/Mocha.Transport.RabbitMQ/Connection/RabbitMQDispatcher.cs	10	14	71.4% 🔴
…/Connection/RabbitMQConsumerManager.cs	224	259	86.5% 🟡
…/Connection/RabbitMQConnectionManagerBase.cs	113	130	86.9% 🟡
…/Middlewares/Receive/RabbitMQAcknowledgementMiddleware.cs	10	10	100.0% 🟢
…/src/Mocha.Transport.RabbitMQ/RabbitMQDispatchEndpoint.cs	4	4	100.0% 🟢
…/src/Mocha.Transport.RabbitMQ/RabbitMQMessagingTransport.cs	2	2	100.0% 🟢
…/src/Mocha.Transport.RabbitMQ/RabbitMQReceiveEndpoint.cs	20	20	100.0% 🟢

Uncovered changed lines (JSON)

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Project coverage: 59.1% (312726/528892 lines)

[github-actions]

✅ Nitro CLI E2E snapshots: no flow recordings changed vs main.