feat: enforce native preloading of neural model to prevent HTTP connection timeouts

backend/main.py

@@ -58,6 +58,18 @@ async def lifespan(app: FastAPI):
 
     app.state.qdrant = _qdrant_client
     app.state.qdrant_ready = _qdrant_ready
+    
+    # -----------------------------------------------------
+    # CRITICAL: Pre-load the 2.3 GB Neural Cross-Encoder
+    # to entirely prevent HF Gateway 60-second 500 timeouts
+    # during user requests.
+    # -----------------------------------------------------
+    import asyncio
+    from src.ml.reranker import _get_reranker
+    logger.info(f"Preloading Neural Reranker `{settings.reranker_model}`. This may take ~60 seconds to cache...")
+    await asyncio.to_thread(_get_reranker)
+    logger.info("Neural Reranker fully loaded into memory!")
+
     yield
     _qdrant_client.close()