Update app.py

app.py

@@ -13,7 +13,7 @@ HF_TOKEN = os.getenv(API_KEY_ENV)
 if not HF_TOKEN:
     raise RuntimeError(f"Missing {API_KEY_ENV}")
 
-MODEL_ID = "openai/gpt-4o-mini"      # efficient chat model
+MODEL_ID = "openai/gpt-oss-20b"  # chat model via HF router
 EMBED_MODEL = "text-embedding-3-small"
 CACHE_FILE = "/tmp/ohamlab_emb_cache.json"