diff --git a/SVSim.UnitTests/Wire/ReplayInfoWireShape.cs b/SVSim.UnitTests/Wire/ReplayInfoWireShape.cs
new file mode 100644
index 0000000..3227f04
--- /dev/null
+++ b/SVSim.UnitTests/Wire/ReplayInfoWireShape.cs
@@ -0,0 +1,98 @@
+using System.Text.Json;
+using MessagePack;
+using SVSim.EmulatedEntrypoint.Models.Dtos.Replay;
+
+namespace SVSim.UnitTests.Wire;
+
+/// <summary>
+/// Literal-prod-JSON parity for /replay/info. Captured from
+/// data_dumps/captures/traffic_prod_misc_clicking.ndjson frame 96.
+/// Catches future wire-key/wire-type drift (the kind that bit card_id vs
+/// cardID on the deck-code endpoint, 2026-05-28).
+/// </summary>
+public class ReplayInfoWireShape
+{
+    private const string CapturedFrame = """
+        {
+          "replay_list": [
+            {
+              "battle_type": "4", "two_pick_type": "0", "deck_format": "2",
+              "battle_id": "234471983876", "is_limit_turn": "0",
+              "opponent_name": "Foo", "class_id": "8", "opponent_class_id": "5",
+              "sub_class_id": "0", "opponent_sub_class_id": "0",
+              "rotation_id": "0", "opponent_rotation_id": "0",
+              "opponent_country_code": "", "chara_id": "8", "opponent_chara_id": "805",
+              "opponent_emblem_id": "721341010", "opponent_degree_id": "120023",
+              "is_win": "0", "battle_start_time": "2026-06-04 17:13:13",
+              "create_time": "2026-06-04 17:16:06"
+            }
+          ],
+          "feature_maintenance_list": []
+        }
+        """;
+
+    [Test]
+    public void Parses_captured_prod_frame_into_dto()
+    {
+        var resp = JsonSerializer.Deserialize<ReplayInfoResponseDto>(CapturedFrame);
+
+        Assert.That(resp, Is.Not.Null);
+        Assert.That(resp!.ReplayList, Has.Count.EqualTo(1));
+
+        var item = resp.ReplayList[0];
+        Assert.That(item.BattleId, Is.EqualTo("234471983876"));
+        Assert.That(item.OpponentName, Is.EqualTo("Foo"));
+        Assert.That(item.OpponentEmblemId, Is.EqualTo("721341010"));
+        Assert.That(item.OpponentDegreeId, Is.EqualTo("120023"));
+        Assert.That(item.IsWin, Is.EqualTo("0"));
+        Assert.That(item.BattleStartTime, Is.EqualTo("2026-06-04 17:13:13"));
+    }
+
+    [Test]
+    public void Serialized_dto_uses_snake_case_wire_keys()
+    {
+        var dto = new ReplayInfoResponseDto
+        {
+            ReplayList = new List<ReplayInfoItemDto>
+            {
+                new()
+                {
+                    BattleType = "4", BattleId = "234471983876", OpponentName = "Foo",
+                    OpponentEmblemId = "721341010", OpponentDegreeId = "120023",
+                    IsWin = "0", BattleStartTime = "2026-06-04 17:13:13",
+                    CreateTime = "2026-06-04 17:16:06",
+                },
+            },
+        };
+
+        var json = JsonSerializer.Serialize(dto, new JsonSerializerOptions
+        {
+            PropertyNamingPolicy = JsonNamingPolicy.SnakeCaseLower,
+        });
+
+        Assert.That(json, Does.Contain("\"battle_id\":\"234471983876\""));
+        Assert.That(json, Does.Contain("\"opponent_emblem_id\":\"721341010\""));
+        Assert.That(json, Does.Contain("\"battle_start_time\":\"2026-06-04 17:13:13\""));
+        // Ensure no camel-case / PascalCase leakage.
+        Assert.That(json, Does.Not.Contain("\"BattleId\""));
+        Assert.That(json, Does.Not.Contain("\"battleId\""));
+    }
+
+    [Test]
+    public void Round_trips_through_MessagePack_preserving_wire_keys()
+    {
+        var original = new ReplayInfoItemDto
+        {
+            BattleType = "4", BattleId = "234471983876", OpponentName = "Foo",
+            OpponentEmblemId = "721341010", IsWin = "1",
+            BattleStartTime = "2026-06-04 17:13:13",
+        };
+
+        var bytes = MessagePackSerializer.Serialize(original);
+        var roundTripped = MessagePackSerializer.Deserialize<ReplayInfoItemDto>(bytes);
+
+        Assert.That(roundTripped.BattleId, Is.EqualTo("234471983876"));
+        Assert.That(roundTripped.OpponentEmblemId, Is.EqualTo("721341010"));
+        Assert.That(roundTripped.IsWin, Is.EqualTo("1"));
+    }
+}