fix(reranker): log reranking failures instead of swallowing them silently (#5717)

mem0/reranker/cohere_reranker.py

@@ -1,3 +1,4 @@
+import logging
 import os
 from typing import List, Dict, Any
 
@@ -9,6 +10,8 @@ try:
 except ImportError:
     COHERE_AVAILABLE = False
 
+logger = logging.getLogger(__name__)
+
 
 class CohereReranker(BaseReranker):
     """Cohere-based reranker implementation."""
@@ -78,8 +81,9 @@ class CohereReranker(BaseReranker):
                 
             return reranked_docs
 
-        except Exception:
+        except Exception as e:
             # Fallback to original order if reranking fails
+            logger.warning("Cohere reranking failed, falling back to original order: %s", e)
             for doc in documents:
                 doc['rerank_score'] = 0.0
             final_top_k = top_k or self.config.top_k

mem0/reranker/huggingface_reranker.py

@@ -1,3 +1,4 @@
+import logging
 from typing import List, Dict, Any, Union
 import numpy as np
 
@@ -12,6 +13,8 @@ try:
 except ImportError:
     TRANSFORMERS_AVAILABLE = False
 
+logger = logging.getLogger(__name__)
+
 
 class HuggingFaceReranker(BaseReranker):
     """HuggingFace Transformers based reranker implementation."""
@@ -139,8 +142,9 @@ class HuggingFaceReranker(BaseReranker):
 
             return reranked_docs
 
-        except Exception:
+        except Exception as e:
             # Fallback to original order if reranking fails
+            logger.warning("HuggingFace reranking failed, falling back to original order: %s", e)
             for doc in documents:
                 doc['rerank_score'] = 0.0
             final_top_k = top_k or self.config.top_k

mem0/reranker/llm_reranker.py

@@ -1,3 +1,4 @@
+import logging
 import re
 from typing import Any, Dict, List, Union
 
@@ -6,6 +7,8 @@ from mem0.configs.rerankers.llm import LLMRerankerConfig
 from mem0.reranker.base import BaseReranker
 from mem0.utils.factory import LlmFactory
 
+logger = logging.getLogger(__name__)
+
 
 class LLMReranker(BaseReranker):
     """LLM-based reranker implementation."""
@@ -151,8 +154,9 @@ class LLMReranker(BaseReranker):
                 scored_doc['rerank_score'] = score
                 scored_docs.append(scored_doc)
 
-            except Exception:
+            except Exception as e:
                 # Fallback: assign neutral score if scoring fails
+                logger.warning("LLM reranking failed for a document, assigning neutral score: %s", e)
                 scored_doc = doc.copy()
                 scored_doc['rerank_score'] = 0.5
                 scored_docs.append(scored_doc)

mem0/reranker/sentence_transformer_reranker.py

@@ -1,3 +1,4 @@
+import logging
 from typing import List, Dict, Any, Union
 import numpy as np
 
@@ -11,6 +12,8 @@ try:
 except ImportError:
     SENTENCE_TRANSFORMERS_AVAILABLE = False
 
+logger = logging.getLogger(__name__)
+
 
 class SentenceTransformerReranker(BaseReranker):
     """Sentence Transformer based reranker implementation."""
@@ -102,8 +105,9 @@ class SentenceTransformerReranker(BaseReranker):
                 
             return reranked_docs
 
-        except Exception:
+        except Exception as e:
             # Fallback to original order if reranking fails
+            logger.warning("SentenceTransformer reranking failed, falling back to original order: %s", e)
             for doc in documents:
                 doc['rerank_score'] = 0.0
             final_top_k = top_k or self.config.top_k

mem0/reranker/zero_entropy_reranker.py

@@ -1,3 +1,4 @@
+import logging
 import os
 from typing import List, Dict, Any
 
@@ -9,6 +10,8 @@ try:
 except ImportError:
     ZERO_ENTROPY_AVAILABLE = False
 
+logger = logging.getLogger(__name__)
+
 
 class ZeroEntropyReranker(BaseReranker):
     """Zero Entropy-based reranker implementation."""
@@ -89,8 +92,9 @@ class ZeroEntropyReranker(BaseReranker):
                 
             return reranked_docs
 
-        except Exception:
+        except Exception as e:
             # Fallback to original order if reranking fails
+            logger.warning("Zero Entropy reranking failed, falling back to original order: %s", e)
             for doc in documents:
                 doc['rerank_score'] = 0.0
             final_top_k = top_k or self.config.top_k