fix: use os.getenv for env vars

inference.py

@@ -19,10 +19,11 @@ from env.cache import CDNCacheEnv, TASK_CONFIGS
 from env.models import Action, Observation
 
 # ─────────────────────────────────────────────
-# Config from environment
+# Config from environment (required by OpenEnv spec)
 # ─────────────────────────────────────────────
-API_BASE_URL = os.environ.get("API_BASE_URL", "https://api.openai.com/v1")
-MODEL_NAME   = os.environ.get("MODEL_NAME", "gpt-4o-mini")
+API_BASE_URL = os.getenv("API_BASE_URL", "https://api.openai.com/v1")
+MODEL_NAME   = os.getenv("MODEL_NAME", "gpt-4o-mini")
+HF_TOKEN     = os.getenv("HF_TOKEN")
 HF_TOKEN     = os.environ.get("HF_TOKEN", "")
 
 if not HF_TOKEN:
@@ -218,4 +219,4 @@ if __name__ == "__main__":
         print(f"[INFO] {r['task_id']}: score={r['score']} reward={r['total_reward']}", file=sys.stderr)
 
     overall = round(sum(r["score"] for r in results) / len(results), 4)
-    print(f"[INFO] Overall score: {overall}", file=sys.stderr)
+    print(f"[INFO] Overall score: {overall}", file=sys.stderr)