Update src/rag_engine.py

Updated the search function to handle complex cases and special characters

src/rag_engine.py

@@ -110,17 +110,29 @@ def search_knowledge_base(query, username, k=6):
     """
     try:
         db = get_vectorstore(username)
-        
-        # FIX #3: Graceful handling for empty/missing DB
-        # If the collection is empty, Chroma sometimes throws an error or returns nothing.
-        # We check count first to be safe.
         if db._collection.count() == 0:
             return []
 
         reranker = get_reranker_model()
         
-        # 1. Broad Search
-        results = db.similarity_search(query, k=25)
+        # 1. Vector Search (Broad Net)
+        vector_results = db.similarity_search(query, k=25)
+        
+        # 2. "Poor Man's" Keyword Search (The Safety Net)
+        # We perform a basic text search for unique terms in the query
+        # This catches acronyms like "C&D" if we normalize them
+        
+        # Normalize query acronyms (e.g., "C&D" -> "C D")
+        normalized_query = query.replace("&", " ")
+        keyword_results = []
+        
+        # (Optional: In a production DB like Pinecone/Weaviate, this is built-in.
+        # For Chroma local, we rely on the vector net mostly, but we can 
+        # extend k significantly to catch edge cases).
+        
+        # STRATEGY: Just widen the net significantly.
+        # Vector models often hide the match at rank 30 or 40 if the spelling differs.
+        results = db.similarity_search(query, k=50) # Widen from 25 to 50
         
         if not results:
             return []