Make reranker a global module object to avoid re-initialization

src/haiku/rag/config.py

@@ -19,8 +19,8 @@ class AppConfig(BaseModel):
     EMBEDDINGS_MODEL: str = "mxbai-embed-large"
     EMBEDDINGS_VECTOR_DIM: int = 1024
 
-    RERANK_MODEL: str = "mixedbread-ai/mxbai-rerank-base-v2"
     RERANK_PROVIDER: str = "mxbai"
+    RERANK_MODEL: str = "mixedbread-ai/mxbai-rerank-base-v2"
 
     QA_PROVIDER: str = "ollama"
     QA_MODEL: str = "qwen3"

src/haiku/rag/reranking/__init__.py

@@ -6,11 +6,21 @@ try:
 except ImportError:
     pass
 
+_reranker: RerankerBase | None = None
+
 
 def get_reranker() -> RerankerBase:
     """
     Factory function to get the appropriate reranker based on the configuration.
     """
+    global _reranker
+    if _reranker is not None:
+        return _reranker
+    if Config.RERANK_PROVIDER == "mxbai":
+        from haiku.rag.reranking.mxbai import MxBAIReranker
+
+        _reranker = MxBAIReranker()
+        return _reranker
 
     if Config.RERANK_PROVIDER == "cohere":
         try:
@@ -21,6 +31,7 @@ def get_reranker() -> RerankerBase:
                 "Please install haiku.rag with the 'cohere' extra:"
                 "uv pip install haiku.rag --extra cohere"
             )
-        return CohereReranker()
+        _reranker = CohereReranker()
+        return _reranker
 
     raise ValueError(f"Unsupported reranker provider: {Config.RERANK_PROVIDER}")