fix: implement $not filter support in ChromaDB vector store (#5485)

mem0/vector_stores/chroma.py

@@ -316,8 +316,32 @@ class ChromaDB(VectorStoreBase):
                     processed_filters.append(or_conditions[0])
             
             elif key == "$not":
-                # Handle NOT conditions - ChromaDB doesn't have direct NOT, so we'll skip for now
-                continue
+                negate_op = {
+                    "eq": "$ne", "ne": "$eq",
+                    "gt": "$lte", "gte": "$lt",
+                    "lt": "$gte", "lte": "$gt",
+                    "in": "$nin", "nin": "$in",
+                }
+                negated_per_group = []
+                for condition in value:
+                    negated_fields = []
+                    for sub_key, sub_value in condition.items():
+                        if isinstance(sub_value, dict):
+                            for op, val in sub_value.items():
+                                neg = negate_op.get(op)
+                                if neg:
+                                    negated_fields.append({sub_key: {neg: val}})
+                        else:
+                            negated_fields.append({sub_key: {"$ne": sub_value}})
+                    if len(negated_fields) > 1:
+                        negated_per_group.append({"$or": negated_fields})
+                    elif len(negated_fields) == 1:
+                        negated_per_group.append(negated_fields[0])
+
+                if len(negated_per_group) > 1:
+                    processed_filters.append({"$and": negated_per_group})
+                elif len(negated_per_group) == 1:
+                    processed_filters.append(negated_per_group[0])
                 
             else:
                 # Regular condition