[mem0ai/mem0#6419]: the mem0 Vertex AI Vector Search integration builds the zero query vector with a hardcoded dimension of 768 and the config has no dimension field, so any index with a different dimension (OpenAI 1536/3072) rejects the query. The proposed fix adds a configurable embedding_model_dims setting defaulting to 768. Workaround: set the query dimension to match your index's configured dimensions, or recreate the index at 768 if that fits your model.

Context: Mem0 GoogleMatchingEngine list(), get_all and delete_all fail for indexes whose embedding dimension is not 768, because the zero query vector is hardcoded to 768 dimensions.