Memory._process_metadata_filters() renames OR→$or and NOT→$not before passing filters to the vector store. Without this fix, $or/$not keys with list values hit _build_field_condition and crash with ValidationError (MatchValue rejects lists). Normalize $or→OR, $not→NOT, $and→AND at the start of _create_filter so both naming conventions work. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>