The one Arazzo condition no tool can evaluate safely

This article details the author's journey building an Arazzo runner, a program that executes API workflows step by step. The core challenge is evaluating success criteria conditions (like $statusCode == 200) in a way that is both safe and portable across different runners. The author initially considered using eval but rejected it due to security risks, then moved to a parser-based approach. However, they discovered deep interoperability issues and corner cases that make safe evaluation difficult. This research led to the creation of @swaggerexpert/arazzo-criterion, a library that faithfully evaluates conditions as per the spec, while being honest about one case no tool can handle safely. The article is highly relevant to IT/TECHNOLOGY, focusing on API specification interpretation, software engineering, and tooling for workflow automation.