diff --git a/dprovenancekit/query.py b/dprovenancekit/query.py
index bdf997b..963021d 100644
--- a/dprovenancekit/query.py
+++ b/dprovenancekit/query.py
@@ -22,10 +22,30 @@
 
 @dataclass(frozen=True)
 class TraceRun:
+    """A finished run's events in ascending ``sequence`` order.
+
+    ``sequence`` is the authoritative causal order (see ``TraceEvent``); the
+    constructor normalizes whatever list it is given (ties keep the caller's
+    relative order), so two runs holding the same events query, diff, align, and
+    gate identically whether they were loaded from a store or assembled by hand.
+    This mirrors the Swift ``TraceRun`` initializer, and keeps the in-memory
+    temporal query evaluator consistent with the SQL backend, which already
+    orders by ``MIN(sequence)``.
+    """
+
     run_id: uuid.UUID
     context_id: str
     events: List[TraceEvent]
 
+    def __post_init__(self) -> None:
+        events = list(self.events)
+        if any(
+            events[i].sequence > events[i + 1].sequence
+            for i in range(len(events) - 1)
+        ):
+            events.sort(key=lambda e: e.sequence)  # sorted() is stable in Python
+            object.__setattr__(self, "events", events)
+
 
 # MARK: - AST nodes --------------------------------------------------------------
 
diff --git a/tests/test_tracerun_normalization.py b/tests/test_tracerun_normalization.py
new file mode 100644
index 0000000..2733a4f
--- /dev/null
+++ b/tests/test_tracerun_normalization.py
@@ -0,0 +1,92 @@
+"""Ports TraceRunNormalizationTests.
+
+Pins the ``TraceRun`` construction invariant: ``events`` is always in ascending
+``sequence`` order (ties keep the caller's relative order), so causal analysis can
+never depend on the order a caller assembled the list. Before this, the in-memory
+temporal query evaluator (``after``/``before``) used list order — diverging from
+both the SQL backend (``MIN(sequence)``) and TRACE_SPEC_v1 — and the diff engine
+manufactured spurious added/removed pairs for hand-assembled out-of-order runs.
+"""
+
+from __future__ import annotations
+
+import uuid
+from dataclasses import dataclass
+
+from dprovenancekit import (
+    TraceDiffEngine,
+    TraceEvent,
+    TracePriority,
+    TraceQueryDSL,
+    TraceableEvent,
+    TraceRun,
+)
+
+
+@dataclass(frozen=True)
+class Step(TraceableEvent):
+    name: str
+    body: str = "b"
+
+    @property
+    def type_identifier(self) -> str:
+        return self.name
+
+    @property
+    def priority(self) -> TracePriority:
+        return TracePriority.CRITICAL
+
+
+def _ev(seq: int, name: str, body: str = "b") -> TraceEvent:
+    return TraceEvent(
+        run_id=uuid.UUID("40000000-0000-0000-0000-000000000001"),
+        context_id="ctx",
+        engine_name="e",
+        schema_version=1,
+        sequence=seq,
+        span_id=None,
+        parent_span_id=None,
+        payload=Step(name=name, body=body),
+    )
+
+
+def _run(events) -> TraceRun:
+    return TraceRun(run_id=uuid.uuid4(), context_id="ctx", events=events)
+
+
+def test_out_of_order_list_is_sorted_by_sequence():
+    run = _run([_ev(2, "C"), _ev(0, "A"), _ev(1, "B")])
+    assert [e.sequence for e in run.events] == [0, 1, 2]
+    assert [e.payload.name for e in run.events] == ["A", "B", "C"]
+
+
+def test_already_sorted_list_is_preserved_verbatim():
+    events = [_ev(0, "A"), _ev(1, "B"), _ev(2, "C")]
+    run = _run(events)
+    assert [e.id for e in run.events] == [e.id for e in events]
+
+
+def test_duplicate_sequences_keep_assembly_order():
+    first, second = _ev(1, "dup", "first"), _ev(1, "dup", "second")
+    run = _run([_ev(2, "tail"), first, second, _ev(0, "head")])
+    assert [e.sequence for e in run.events] == [0, 1, 1, 2]
+    assert run.events[1].payload.body == "first"
+    assert run.events[2].payload.body == "second"
+
+
+def test_temporal_query_matches_sql_semantics_on_unsorted_input():
+    # Causally A(0) runs before B(1); the list was assembled B-first. The
+    # in-memory evaluator used list order here and answered False, while the
+    # SQL backend (MIN(sequence)) answered True for the same run.
+    run = _run([_ev(1, "B"), _ev(0, "A")])
+    query = TraceQueryDSL().requiring_followed_by("A", followed_by="B")
+    assert query.ast.evaluate(run) is True
+
+
+def test_diff_is_assembly_order_invariant():
+    sorted_run = _run([_ev(0, "authorize", "a"), _ev(1, "charge", "c")])
+    shuffled = _run([_ev(1, "charge", "c"), _ev(0, "authorize", "a")])
+    result = TraceDiffEngine().diff(base=sorted_run, comparison=shuffled)
+    assert result.is_identical, (
+        "same events, same causal order — assembly order must not manufacture changes"
+    )