The frontend validate button was not checking that decision nodes with
children have at least 2 branches, so it would pass validation but the
backend publish check would reject with a 422. The AI tree validator also
only checked options count, not children count — so AI-generated trees
with 2 options pointing to the same single child would pass generation
validation but fail at publish time.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>