Delivery guarantees

Durable

The exchange never loses an accepted message. A queued-unoccupied send is persisted and delivered when a station next attends the address. The durable buffer survives daemon restarts.

At-least-once

Delivery is at-least-once. A message may occasionally be delivered more than once (for example after a reconnect, or in push mode after a session re-attach). Consumers dedupe by message id. A message remains eligible for delivery until the recipient explicitly acks it:

telex ack --address <addr> --id <message-id>

Printing or displaying a message is transport only; it is not consumption. This is deliberate: the safe failure direction is a duplicate, never a silent loss.

Ack is per recipient

Ack consumes (message_id, recipient-address). Acking for address A does not consume the same message id for a CC recipient B, so observers see their own copy.

Terminal workflow disposition is separate

Ack is transport consumption. Closing out the work is a separate disposition (handle, reject, or close). A message can be acked (consumed from the delivery buffer) while still needing a terminal workflow disposition.

Next: Disposition