The Hidden Rules of bpmn-io: When Documentation Isn't Enough

This article exposes critical undocumented behaviors in bpmn-io Form-JS providers that cause silent failures when developers extend the properties panel. Understanding the middleware pattern, priority semantics, and entry ID uniqueness rules is essential to avoid bugs that fail silently with no error messages. The gap between official documentation and actual behavior represents a significant learning curve for any developer working with bpmn-io's extensibility features.