Written against main at the time of publishing. Every regex and line number is cited so you can re-check with grep -n and there's a runnable reproduction at the end that needs no build. TL;DR A PROMPT_TEMPLATE artifact in Apicurio Registry is rendered by three different pieces of code that don't share an engine and don't agree on what a template means beyond a plain {{name}} . Add a space, a dot, or an {{#if}} block and the same stored template renders three differe...