internal/

Package delivery runs the delivery pipeline both messaging lanes share: everything that happens to one consumed message between "bytes arrived" and "outcome recorded" — trace extraction from the lane's carrier, the consumer span, the per-message lease scope, handler invocation, panic-to-error, one consumed record at completion, and the lane's own outcome line.

Package lanecontract holds the contract every messaging lane driving the delivery pipeline must satisfy, and the fixture that drives it.