diff --git a/trace_agg.py/tests/test_core.py b/trace_agg.py/tests/test_core.py
new file mode 100644
index 0000000..24e15df
--- /dev/null
+++ b/trace_agg.py/tests/test_core.py
@@ -0,0 +1,40 @@
+import pytest
+from trace_agg.core import analyze_trace, TraceData
+
+@pytest.fixture
+def sample_trace():
+    return [
+        TraceData(corr_id=1, event_type='write_pre', timestamp=0.0),
+        TraceData(corr_id=1, event_type='read_between_steps', timestamp=0.5),
+        TraceData(corr_id=1, event_type='write_post', timestamp=1.0),
+        TraceData(corr_id=2, event_type='write_pre', timestamp=2.0),
+        TraceData(corr_id=2, event_type='write_post', timestamp=2.2),
+        TraceData(corr_id=2, event_type='read_between_steps', timestamp=3.0)
+    ]
+
+def test_analyze_trace_basic(sample_trace):
+    result = analyze_trace(sample_trace)
+    assert isinstance(result, dict)
+    assert all(isinstance(k, int) for k in result.keys())
+    assert 1 in result and 2 in result
+
+def test_analyze_trace_contains_expected_metrics(sample_trace):
+    result = analyze_trace(sample_trace)
+    metrics = result[1]
+    assert 'window_duration' in metrics
+    assert 'retry_free_reads' in metrics
+    assert 'sequence_distance' in metrics
+
+def test_trace_data_structure_validation():
+    trace = TraceData(corr_id=7, event_type='write_pre', timestamp=0.1234)
+    assert trace.corr_id == 7
+    assert trace.event_type == 'write_pre'
+    assert isinstance(trace.timestamp, float)
+
+def test_analyze_trace_handles_empty_input():
+    result = analyze_trace([])
+    assert result == {} or isinstance(result, dict)
+
+def test_analyze_trace_invalid_input_type():
+    with pytest.raises(Exception):
+        analyze_trace([{'corr_id': 1, 'event_type': 'write_pre', 'timestamp': 0.0}])
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