feat: consolidate legacy parity migration baseline

tests/MBN_STOCK_WEBVIEW.LegacyApplication.Tests/LegacyOverseasSelectionWorkflowTests.cs

@@ -276,6 +276,29 @@ public sealed class LegacyOverseasSelectionWorkflowTests
         }
     }
 
+    [Fact]
+    public async Task CurrentProviderPunctuationRemainsAnExactBoundStockIdentity()
+    {
+        var workflow = CreateWorkflow(stocks:
+        [
+            new("Ampersand", "IDX@A&B", "US"),
+            new("Parenthesized", "IDX@(A)", "US")
+        ]);
+
+        var searched = await workflow.SearchStocksAsync(string.Empty);
+
+        Assert.Equal(LegacyOverseasSearchStatus.Ready, searched.Stock.Status);
+        Assert.Equal(2, searched.Stock.Results.Count);
+        workflow.SelectStock(searched.Stock.Results[0].SelectionId);
+        Assert.Equal(
+            "IDX@A&B|US|1",
+            workflow.MaterializePlaylistDraft("stock-current").Selection.DataCode);
+        workflow.SelectStock(searched.Stock.Results[1].SelectionId);
+        Assert.Equal(
+            "IDX@(A)|US|1",
+            workflow.MaterializePlaylistDraft("stock-candle-5d").Selection.DataCode);
+    }
+
     [Theory]
     [InlineData(false, false, "")]
     [InlineData(true, false, "MA5")]