diff --git a/cognee/tests/unit/shared/test_usage_logger.py b/cognee/tests/unit/shared/test_usage_logger.py
new file mode 100644
index 000000000..54b49454c
--- /dev/null
+++ b/cognee/tests/unit/shared/test_usage_logger.py
@@ -0,0 +1,216 @@
+"""Unit tests for usage logger core functions."""
+
+import pytest
+from datetime import datetime, timezone
+from uuid import UUID
+from types import SimpleNamespace
+
+from cognee.shared.usage_logger import (
+    _sanitize_value,
+    _sanitize_dict_key,
+    _get_param_names,
+    _get_param_defaults,
+    _extract_user_id,
+    _extract_parameters,
+    log_usage,
+)
+from cognee.shared.exceptions import UsageLoggerError
+
+
+class TestSanitizeValue:
+    """Test _sanitize_value function."""
+
+    @pytest.mark.parametrize("value,expected", [
+        (None, None),
+        ("string", "string"),
+        (42, 42),
+        (3.14, 3.14),
+        (True, True),
+        (False, False),
+    ])
+    def test_basic_types(self, value, expected):
+        assert _sanitize_value(value) == expected
+
+    def test_uuid_and_datetime(self):
+        """Test UUID and datetime serialization."""
+        uuid_val = UUID("123e4567-e89b-12d3-a456-426614174000")
+        dt = datetime(2024, 1, 15, 12, 30, 45, tzinfo=timezone.utc)
+        
+        assert _sanitize_value(uuid_val) == "123e4567-e89b-12d3-a456-426614174000"
+        assert _sanitize_value(dt) == "2024-01-15T12:30:45+00:00"
+
+    def test_collections(self):
+        """Test list, tuple, and dict serialization."""
+        assert _sanitize_value([1, "string", UUID("123e4567-e89b-12d3-a456-426614174000"), None]) == [
+            1, "string", "123e4567-e89b-12d3-a456-426614174000", None
+        ]
+        assert _sanitize_value((1, "string", True)) == [1, "string", True]
+        assert _sanitize_value({"key": UUID("123e4567-e89b-12d3-a456-426614174000")}) == {
+            "key": "123e4567-e89b-12d3-a456-426614174000"
+        }
+        assert _sanitize_value([]) == []
+        assert _sanitize_value({}) == {}
+
+    def test_nested_and_complex(self):
+        """Test nested structures and non-serializable types."""
+        # Nested structure
+        nested = {"level1": {"level2": {"level3": [1, 2, {"nested": "value"}]}}}
+        assert _sanitize_value(nested)["level1"]["level2"]["level3"][2]["nested"] == "value"
+        
+        # Non-serializable
+        class CustomObject:
+            def __str__(self):
+                return "<CustomObject instance>"
+        
+        result = _sanitize_value(CustomObject())
+        assert isinstance(result, str)
+        assert "<cannot be serialized" in result or "<CustomObject" in result
+
+
+class TestSanitizeDictKey:
+    """Test _sanitize_dict_key function."""
+
+    @pytest.mark.parametrize("key,expected_contains", [
+        ("simple_key", "simple_key"),
+        (UUID("123e4567-e89b-12d3-a456-426614174000"), "123e4567-e89b-12d3-a456-426614174000"),
+        ((1, 2, 3), ["1", "2"]),
+    ])
+    def test_key_types(self, key, expected_contains):
+        result = _sanitize_dict_key(key)
+        assert isinstance(result, str)
+        if isinstance(expected_contains, list):
+            assert all(item in result for item in expected_contains)
+        else:
+            assert expected_contains in result
+
+    def test_non_serializable_key(self):
+        class BadKey:
+            def __str__(self):
+                return "<BadKey instance>"
+        
+        result = _sanitize_dict_key(BadKey())
+        assert isinstance(result, str)
+        assert "<key:" in result or "<BadKey" in result
+
+
+class TestGetParamNames:
+    """Test _get_param_names function."""
+
+    @pytest.mark.parametrize("func_def,expected", [
+        (lambda a, b, c: None, ["a", "b", "c"]),
+        (lambda a, b=42, c="default": None, ["a", "b", "c"]),
+        (lambda a, **kwargs: None, ["a", "kwargs"]),
+        (lambda *args: None, ["args"]),
+    ])
+    def test_param_extraction(self, func_def, expected):
+        assert _get_param_names(func_def) == expected
+
+    def test_async_function(self):
+        async def func(a, b):
+            pass
+        assert _get_param_names(func) == ["a", "b"]
+
+
+class TestGetParamDefaults:
+    """Test _get_param_defaults function."""
+
+    @pytest.mark.parametrize("func_def,expected", [
+        (lambda a, b=42, c="default", d=None: None, {"b": 42, "c": "default", "d": None}),
+        (lambda a, b, c: None, {}),
+        (lambda a, b=10, c="test", d=None: None, {"b": 10, "c": "test", "d": None}),
+    ])
+    def test_default_extraction(self, func_def, expected):
+        assert _get_param_defaults(func_def) == expected
+
+
+class TestExtractUserId:
+    """Test _extract_user_id function."""
+
+    def test_user_extraction(self):
+        """Test extracting user_id from kwargs and args."""
+        user1 = SimpleNamespace(id=UUID("123e4567-e89b-12d3-a456-426614174000"))
+        user2 = SimpleNamespace(id="user-123")
+        
+        # From kwargs
+        assert _extract_user_id((), {"user": user1}, ["user", "other"]) == "123e4567-e89b-12d3-a456-426614174000"
+        # From args
+        assert _extract_user_id((user2, "other"), {}, ["user", "other"]) == "user-123"
+        # Not present
+        assert _extract_user_id(("arg1",), {}, ["param1"]) is None
+        # None value
+        assert _extract_user_id((None,), {}, ["user"]) is None
+        # No id attribute
+        assert _extract_user_id((SimpleNamespace(name="test"),), {}, ["user"]) is None
+
+
+class TestExtractParameters:
+    """Test _extract_parameters function."""
+
+    def test_parameter_extraction(self):
+        """Test parameter extraction with various scenarios."""
+        def func1(param1, param2, user=None):
+            pass
+        def func2(param1, param2=42, param3="default", user=None):
+            pass
+        def func3():
+            pass
+        def func4(param1, user):
+            pass
+        
+        # Kwargs only
+        result = _extract_parameters((), {"param1": "v1", "param2": 42}, _get_param_names(func1), func1)
+        assert result == {"param1": "v1", "param2": 42}
+        assert "user" not in result
+        
+        # Args only
+        result = _extract_parameters(("v1", 42), {}, _get_param_names(func1), func1)
+        assert result == {"param1": "v1", "param2": 42}
+        
+        # Mixed args/kwargs
+        result = _extract_parameters(("v1",), {"param3": "v3"}, _get_param_names(func2), func2)
+        assert result["param1"] == "v1" and result["param3"] == "v3"
+        
+        # Defaults included
+        result = _extract_parameters(("v1",), {}, _get_param_names(func2), func2)
+        assert result["param1"] == "v1" and result["param2"] == 42 and result["param3"] == "default"
+        
+        # No parameters
+        assert _extract_parameters((), {}, _get_param_names(func3), func3) == {}
+        
+        # User excluded
+        user = SimpleNamespace(id="user-123")
+        result = _extract_parameters(("v1", user), {}, _get_param_names(func4), func4)
+        assert result == {"param1": "v1"} and "user" not in result
+        
+        # Fallback when inspection fails
+        class BadFunc:
+            pass
+        result = _extract_parameters(("arg1", "arg2"), {}, [], BadFunc())
+        assert "arg_0" in result or "arg_1" in result
+
+
+class TestDecoratorValidation:
+    """Test decorator validation and behavior."""
+
+    def test_decorator_validation(self):
+        """Test decorator validation and metadata preservation."""
+        # Sync function raises error
+        with pytest.raises(UsageLoggerError, match="requires an async function"):
+            @log_usage()
+            def sync_func():
+                pass
+        
+        # Async function accepted
+        @log_usage()
+        async def async_func():
+            pass
+        assert callable(async_func)
+        
+        # Metadata preserved
+        @log_usage(function_name="test_func", log_type="test")
+        async def test_func(param1: str, param2: int = 42):
+            """Test docstring."""
+            return param1
+        
+        assert test_func.__name__ == "test_func"
+        assert "Test docstring" in test_func.__doc__