21c7aa31ea1f5431192d994f5afb09dad49e8389
The PATCH "clear colour" path sent an empty string, which violates the hex CHECK constraint and never falls back to the category colour. Map '' to NULL via NULLIF in the tag insert/update so a cleared or omitted colour is stored as NULL. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>