Résumé : Reasoning on Constraint Handling Rules (CHR) programs and their executional behaviour is often ad-hoc and outside of a formal system. This is a pity, because \chr\ subsumes a wide range of important automated reasoning services. Mapping \chr\ to Transaction Logic (\tr) combines \chr\ rule specification, \chr\ rule application, and reasoning on \chr\ programs and \chr\ derivations inside one formal system which is executable. This new \tr\ semantics obviates the need for disjoint declarative and operational semantics.