force offline local MiniLM (no internet, no cache)

rag.py

@@ -103,7 +103,6 @@ def get_texts() -> List[str]:
         print(f"⚠ Dataset fetch failed: {e} – using empty corpus")
         return []
 
-# ------------------------------------------------------------------
 # ------------------------------------------------------------------
 @lru_cache(maxsize=1)
 def get_vectorstore() -> FAISS:
@@ -115,6 +114,10 @@ def get_vectorstore() -> FAISS:
         os.path.join(os.path.dirname(__file__), "st_model")
     )
 
+    # force transformers to read local files only
+    os.environ["TRANSFORMERS_OFFLINE"] = "1"
+    os.environ["HF_DATASETS_OFFLINE"] = "1"
+
     from sentence_transformers import SentenceTransformer
     model = SentenceTransformer(local_model_path, device="cpu", cache_folder=None)