diff --git a/tests/test_logging_utils.py b/tests/test_logging_utils.py
new file mode 100644
index 00000000..7c4c983a
--- /dev/null
+++ b/tests/test_logging_utils.py
@@ -0,0 +1,82 @@
+import json
+
+from velvetflow import logging_utils
+
+
+def test_configure_run_logging_sets_and_resets_run_id():
+    assert logging_utils.current_run_id() is None
+
+    token = logging_utils.configure_run_logging(run_id="run-123")
+    assert token is not None
+    assert logging_utils.current_run_id() == "run-123"
+
+    logging_utils._RUN_ID.reset(token)
+    assert logging_utils.current_run_id() is None
+
+
+def test_use_trace_context_sets_current_and_resets():
+    context = logging_utils.TraceContext("trace-1", "span-1", "span-name")
+
+    with logging_utils.use_trace_context(context):
+        current = logging_utils.current_trace_context()
+        assert current is not None
+        assert current.trace_id == "trace-1"
+        assert current.span_id == "span-1"
+        assert current.span_name == "span-name"
+
+    assert logging_utils.current_trace_context() is None
+
+
+def test_log_event_includes_context_and_payload_override(tmp_path, capsys):
+    log_path = tmp_path / "events.jsonl"
+    token = logging_utils.configure_run_logging(run_id="run-123", log_file=log_path)
+    context = logging_utils.TraceContext("trace-1", "span-1", "span-name")
+
+    with logging_utils.use_trace_context(context):
+        logging_utils.log_event(
+            "hello",
+            payload={"node_id": "node-1", "action_id": "action-1", "extra": "data"},
+        )
+
+    output = capsys.readouterr().out.strip().splitlines()[-1]
+    record = json.loads(output)
+    assert record["workflow_run_id"] == "run-123"
+    assert record["trace_id"] == "trace-1"
+    assert record["span_id"] == "span-1"
+    assert record["node_id"] == "node-1"
+    assert record["action_id"] == "action-1"
+    assert record["payload"]["extra"] == "data"
+
+    logging_utils._RUN_ID.reset(token)
+
+
+def test_log_llm_message_serializes_tool_calls(tmp_path, capsys):
+    class DummyFunction:
+        def __init__(self, name, arguments):
+            self.name = name
+            self.arguments = arguments
+
+    class DummyToolCall:
+        def __init__(self, tool_id, tool_type, function):
+            self.id = tool_id
+            self.type = tool_type
+            self.function = function
+
+    class DummyMessage:
+        def __init__(self, role, content, tool_calls):
+            self.role = role
+            self.content = content
+            self.tool_calls = tool_calls
+
+    logging_utils.configure_run_logging(log_file=tmp_path / "llm.jsonl")
+
+    function = DummyFunction("search", {"query": "hello"})
+    tool_call = DummyToolCall("tool-1", "function", function)
+    message = DummyMessage("assistant", "hi", [tool_call])
+    logging_utils.log_llm_message("gpt-test", message, operation="demo")
+
+    output = capsys.readouterr().out.strip().splitlines()[-1]
+    record = json.loads(output)
+    tool_calls = record["payload"]["message"]["tool_calls"]
+    assert tool_calls[0]["function"]["name"] == "search"
+    assert tool_calls[0]["function"]["arguments"] == {"query": "hello"}