diff --git a/tests/alerts/test_alert_deriver_base.py b/tests/alerts/test_alert_deriver_base.py
new file mode 100644
index 00000000..662dacf0
--- /dev/null
+++ b/tests/alerts/test_alert_deriver_base.py
@@ -0,0 +1,115 @@
+"""Unit tests for AlertDeriver.get_threshold / get_threshold_async."""
+
+from __future__ import annotations
+
+import pytest
+
+from collector.alerts.base import AlertDeriver
+
+
+class _ConcreteDeriver(AlertDeriver):
+    """Minimal concrete subclass to exercise the abstract base."""
+
+    def derive(self, events):
+        return []
+
+
+def test_get_threshold_no_policy_getter_returns_default():
+    deriver = _ConcreteDeriver()
+
+    result = deriver.get_threshold("tool_loop", default_threshold=3.0)
+
+    assert result == 3.0
+
+
+def test_get_threshold_sync_policy_returns_threshold_value():
+    def policy_getter(alert_type, agent_name):
+        return {"enabled": True, "threshold_value": 7.5}
+
+    deriver = _ConcreteDeriver(policy_getter=policy_getter)
+
+    result = deriver.get_threshold("tool_loop", agent_name="agent-1", default_threshold=1.0)
+
+    assert result == 7.5
+
+
+def test_get_threshold_disabled_policy_returns_default():
+    def policy_getter(alert_type, agent_name):
+        return {"enabled": False, "threshold_value": 7.5}
+
+    deriver = _ConcreteDeriver(policy_getter=policy_getter)
+
+    result = deriver.get_threshold("tool_loop", default_threshold=2.0)
+
+    assert result == 2.0
+
+
+def test_get_threshold_policy_getter_returns_none():
+    def policy_getter(alert_type, agent_name):
+        return None
+
+    deriver = _ConcreteDeriver(policy_getter=policy_getter)
+
+    result = deriver.get_threshold("tool_loop", default_threshold=4.0)
+
+    assert result == 4.0
+
+
+@pytest.mark.filterwarnings("ignore:coroutine.*was never awaited:RuntimeWarning")
+def test_get_threshold_async_policy_getter_returns_default_immediately():
+    async def policy_getter(alert_type, agent_name):
+        return {"enabled": True, "threshold_value": 9.0}
+
+    deriver = _ConcreteDeriver(policy_getter=policy_getter)
+
+    # get_threshold (sync) cannot await; an async getter must fall back to default.
+    result = deriver.get_threshold("tool_loop", default_threshold=5.0)
+
+    assert result == 5.0
+
+
+@pytest.mark.asyncio
+async def test_get_threshold_async_no_policy_getter_returns_default():
+    deriver = _ConcreteDeriver()
+
+    result = await deriver.get_threshold_async("tool_loop", default_threshold=3.0)
+
+    assert result == 3.0
+
+
+@pytest.mark.asyncio
+async def test_get_threshold_async_sync_policy_returns_threshold_value():
+    def policy_getter(alert_type, agent_name):
+        return {"enabled": True, "threshold_value": 6.0}
+
+    deriver = _ConcreteDeriver(policy_getter=policy_getter)
+
+    result = await deriver.get_threshold_async("tool_loop", default_threshold=1.0)
+
+    assert result == 6.0
+
+
+@pytest.mark.asyncio
+async def test_get_threshold_async_awaits_coroutine_policy_getter():
+    async def policy_getter(alert_type, agent_name):
+        return {"enabled": True, "threshold_value": 8.0}
+
+    deriver = _ConcreteDeriver(policy_getter=policy_getter)
+
+    result = await deriver.get_threshold_async(
+        "tool_loop", agent_name="agent-1", default_threshold=1.0
+    )
+
+    assert result == 8.0
+
+
+@pytest.mark.asyncio
+async def test_get_threshold_async_disabled_policy_returns_default():
+    async def policy_getter(alert_type, agent_name):
+        return {"enabled": False, "threshold_value": 8.0}
+
+    deriver = _ConcreteDeriver(policy_getter=policy_getter)
+
+    result = await deriver.get_threshold_async("tool_loop", default_threshold=2.0)
+
+    assert result == 2.0