diff --git a/tests/test_config.py b/tests/test_config.py
index 5ca1107..1593817 100644
--- a/tests/test_config.py
+++ b/tests/test_config.py
@@ -9,6 +9,7 @@ environment restored so later tests see normal module state.
 from __future__ import annotations
 
 import importlib
+import os
 
 import pytest
 
@@ -18,6 +19,13 @@ import app.config as config
 @pytest.fixture(autouse=True)
 def _restore_config_module():
     yield
+    # config.py's write-back (`os.environ["CF_ORCH_URL"] = GPU_SERVER_URL`) is a
+    # module-level side effect monkeypatch never sees, so it can't auto-revert
+    # it — without this explicit cleanup, a value set here leaks into every
+    # other test in the session (e.g. shelve tests' get_llm_config() checks).
+    os.environ.pop("CF_ORCH_URL", None)
+    os.environ.pop("GPU_SERVER_URL", None)
+    os.environ.pop("CF_LICENSE_KEY", None)
     importlib.reload(config)