fix(reranker): align llm_reranker default model with SDK default (#6703)

mem0/configs/rerankers/llm.py

@@ -10,7 +10,7 @@ class LLMRerankerConfig(BaseRerankerConfig):
     Configuration for LLM-based reranker.
     
     Attributes:
-        model (str): LLM model to use for reranking. Defaults to "gpt-4o-mini".
+        model (str): LLM model to use for reranking. Defaults to "gpt-5-mini".
         api_key (str): API key for the LLM provider.
         provider (str): LLM provider. Defaults to "openai".
         top_k (int): Number of top documents to return after reranking.
@@ -20,7 +20,7 @@ class LLMRerankerConfig(BaseRerankerConfig):
     """
     
     model: str = Field(
-        default="gpt-4o-mini",
+        default="gpt-5-mini",
         description="LLM model to use for reranking"
     )
     api_key: Optional[str] = Field(

mem0/reranker/llm_reranker.py

@@ -27,7 +27,7 @@ class LLMReranker(BaseReranker):
             # Convert BaseRerankerConfig to LLMRerankerConfig with defaults
             config = LLMRerankerConfig(
                 provider=getattr(config, 'provider', 'openai'),
-                model=getattr(config, 'model', 'gpt-4o-mini'),
+                model=getattr(config, 'model', 'gpt-5-mini'),
                 api_key=getattr(config, 'api_key', None),
                 top_k=getattr(config, 'top_k', None),
                 temperature=0.0,  # Default for reranking