Hotel PMS has one root problem: the interface is the API

The article argues that bloated front-desk interfaces and month-end reconciliation pain in hotel PMS stem from the same architectural defect: business logic written into the UI layer rather than behind it. This causes menus to multiply and leaves no canonical event log, so each connected system keeps its own partial copy of the truth. Conversational and agentic interfaces expose this flaw because agents need structured, documented, permissioned APIs. The fix is to separate the domain model from the presentation layer, with an event-sourced record and versioned API.