diff --git a/tests/tui_gateway/test_goal_command.py b/tests/tui_gateway/test_goal_command.py
index 050b36bc877..d06f5b8fbbd 100644
--- a/tests/tui_gateway/test_goal_command.py
+++ b/tests/tui_gateway/test_goal_command.py
@@ -44,11 +44,17 @@ def server(hermes_home):
     ):
         mod = importlib.import_module("tui_gateway.server")
         yield mod
+        # Reset module-level session state without re-importing. importlib.reload
+        # would re-register the module's atexit hooks (ThreadPoolExecutor
+        # shutdown, _shutdown_sessions); the duplicates race the stderr
+        # buffer at interpreter shutdown and surface as Fatal Python error:
+        # _enter_buffered_busy. Clearing the per-session dicts gives the
+        # next test a clean slate; _methods is NOT cleared because it's
+        # populated at module import time and re-registration only happens
+        # via reload (which we don't do).
         mod._sessions.clear()
         mod._pending.clear()
         mod._answers.clear()
-        mod._methods.clear()
-        importlib.reload(mod)
 
 
 @pytest.fixture()
diff --git a/tests/tui_gateway/test_protocol.py b/tests/tui_gateway/test_protocol.py
index a26a360a24d..f2f68efbf55 100644
--- a/tests/tui_gateway/test_protocol.py
+++ b/tests/tui_gateway/test_protocol.py
@@ -30,11 +30,17 @@ def server():
         import importlib
         mod = importlib.import_module("tui_gateway.server")
         yield mod
+        # Reset module-level session state without re-importing. importlib.reload
+        # would re-register the module's atexit hooks (ThreadPoolExecutor
+        # shutdown, _shutdown_sessions); the duplicates race the stderr
+        # buffer at interpreter shutdown and surface as Fatal Python error:
+        # _enter_buffered_busy. Clearing the per-session dicts gives the
+        # next test a clean slate; _methods is NOT cleared because it's
+        # populated at module import time and re-registration only happens
+        # via reload (which we don't do).
         mod._sessions.clear()
         mod._pending.clear()
         mod._answers.clear()
-        mod._methods.clear()
-        importlib.reload(mod)
 
 
 @pytest.fixture()
diff --git a/tests/tui_gateway/test_review_summary_callback.py b/tests/tui_gateway/test_review_summary_callback.py
index 9fc7f54ddc6..f2d97f1a487 100644
--- a/tests/tui_gateway/test_review_summary_callback.py
+++ b/tests/tui_gateway/test_review_summary_callback.py
@@ -34,11 +34,17 @@ def server():
 
         mod = importlib.import_module("tui_gateway.server")
         yield mod
+        # Reset module-level session state without re-importing. importlib.reload
+        # would re-register the module's atexit hooks (ThreadPoolExecutor
+        # shutdown, _shutdown_sessions); the duplicates race the stderr
+        # buffer at interpreter shutdown and surface as Fatal Python error:
+        # _enter_buffered_busy. Clearing the per-session dicts gives the
+        # next test a clean slate; _methods is NOT cleared because it's
+        # populated at module import time and re-registration only happens
+        # via reload (which we don't do).
         mod._sessions.clear()
         mod._pending.clear()
         mod._answers.clear()
-        mod._methods.clear()
-        importlib.reload(mod)
 
 
 def test_init_session_attaches_background_review_callback(server, monkeypatch):