undo

Defines compensation logic with "and undo { ... }" syntax.

The compensation is executed with a CompensationScope receiver, providing:

• result: The result from this step's forward action

• state: Current saga state (includes updates from later steps!)

This enables "smart compensation" where earlier steps can make decisions based on the execution progress of later steps.

Example:

and undo {
    // `state` contains updates from ALL completed steps
    when {
        state.escrowCaptured -> cashManager.dispenseCashRefund(state.paymentAmount)
        state.paymentAmount > 0 -> cashManager.returnEscrow()
        else -> cashManager.disableAcceptors()
    }
}