diff --git a/tests/agent/test_reasoning_stale_timeout_floor.py b/tests/agent/test_reasoning_stale_timeout_floor.py
index 196c34f2dc7..3177b585ab4 100644
--- a/tests/agent/test_reasoning_stale_timeout_floor.py
+++ b/tests/agent/test_reasoning_stale_timeout_floor.py
@@ -161,11 +161,13 @@ def test_reasoning_floor_applies_to_nemotron_3_ultra(monkeypatch, tmp_path):
     monkeypatch.delenv("HERMES_API_CALL_STALE_TIMEOUT", raising=False)
     _write_config(tmp_path, "")
 
-    # Clear any cached config from prior tests in this session.
-    import importlib
-    from hermes_cli import config as cfg_mod, timeouts as to_mod
-    importlib.reload(cfg_mod)
-    importlib.reload(to_mod)
+    # Isolate the floor path from leaked provider config: with no per-model /
+    # per-provider stale_timeout_seconds, the resolver falls through to the
+    # reasoning floor.  Patch the lookup to return None deterministically
+    # rather than relying on importlib.reload of shared config modules, which
+    # races other tests in the same xdist worker (#52217 flake).
+    import run_agent
+    monkeypatch.setattr(run_agent, "get_provider_stale_timeout", lambda *a, **k: None)
 
     agent = _make_agent(
         tmp_path,
@@ -190,10 +192,9 @@ def test_reasoning_floor_applies_to_opus_4_thinking(monkeypatch, tmp_path):
     monkeypatch.delenv("HERMES_API_CALL_STALE_TIMEOUT", raising=False)
     _write_config(tmp_path, "")
 
-    import importlib
-    from hermes_cli import config as cfg_mod, timeouts as to_mod
-    importlib.reload(cfg_mod)
-    importlib.reload(to_mod)
+    # Deterministic floor path — see test_reasoning_floor_applies_to_nemotron_3_ultra.
+    import run_agent
+    monkeypatch.setattr(run_agent, "get_provider_stale_timeout", lambda *a, **k: None)
 
     agent = _make_agent(
         tmp_path,
@@ -216,19 +217,12 @@ def test_reasoning_floor_never_overrides_explicit_user_config(monkeypatch, tmp_p
     """
     monkeypatch.setenv("HERMES_HOME", str(tmp_path))
     (tmp_path / ".env").write_text("", encoding="utf-8")
-    _write_config(tmp_path, """\
-providers:
-  nvidia:
-    models:
-      nvidia/nemotron-3-ultra-550b-a55b:
-        stale_timeout_seconds: 60
-""")
     monkeypatch.delenv("HERMES_API_CALL_STALE_TIMEOUT", raising=False)
 
-    import importlib
-    from hermes_cli import config as cfg_mod, timeouts as to_mod
-    importlib.reload(cfg_mod)
-    importlib.reload(to_mod)
+    # Explicit per-model config resolves to 60s (priority 1). The resolver
+    # must short-circuit on this and never consult the reasoning floor.
+    import run_agent
+    monkeypatch.setattr(run_agent, "get_provider_stale_timeout", lambda *a, **k: 60.0)
 
     agent = _make_agent(
         tmp_path,
@@ -251,10 +245,9 @@ def test_reasoning_floor_loses_to_env_var_when_no_floor_match(monkeypatch, tmp_p
     monkeypatch.setenv("HERMES_API_CALL_STALE_TIMEOUT", "300")
     _write_config(tmp_path, "")
 
-    import importlib
-    from hermes_cli import config as cfg_mod, timeouts as to_mod
-    importlib.reload(cfg_mod)
-    importlib.reload(to_mod)
+    # No provider config -> resolver consults the env var (priority 3).
+    import run_agent
+    monkeypatch.setattr(run_agent, "get_provider_stale_timeout", lambda *a, **k: None)
 
     agent = _make_agent(
         tmp_path,
@@ -274,10 +267,9 @@ def test_non_reasoning_model_keeps_default(monkeypatch, tmp_path):
     monkeypatch.delenv("HERMES_API_CALL_STALE_TIMEOUT", raising=False)
     _write_config(tmp_path, "")
 
-    import importlib
-    from hermes_cli import config as cfg_mod, timeouts as to_mod
-    importlib.reload(cfg_mod)
-    importlib.reload(to_mod)
+    # No provider config, no env var, no floor match -> 90s implicit default.
+    import run_agent
+    monkeypatch.setattr(run_agent, "get_provider_stale_timeout", lambda *a, **k: None)
 
     agent = _make_agent(
         tmp_path,