feat: complete legacy UI and playout parity migration

tests/MBN_STOCK_WEBVIEW.LegacyBridge.Tests/LegacyTabActivationBridgeTests.cs

@@ -0,0 +1,36 @@
+using MBN_STOCK_WEBVIEW.LegacyApplication;
+
+namespace MBN_STOCK_WEBVIEW.LegacyBridge.Tests;
+
+public sealed class LegacyTabActivationBridgeTests
+{
+    [Theory]
+    [InlineData("theme", LegacyOperatorTabId.Theme)]
+    [InlineData("expert", LegacyOperatorTabId.Expert)]
+    public void SelectTab_CarriesOnlyClosedTabIdentity(
+        string tabId,
+        LegacyOperatorTabId expected)
+    {
+        Assert.True(LegacyBridgeProtocol.TryParseIntent(
+            $"{{\"type\":\"select-tab\",\"payload\":{{\"tabId\":\"{tabId}\"}}}}",
+            out var parsed,
+            out _));
+
+        Assert.Equal(expected, Assert.IsType<LegacySelectTabIntent>(parsed).TabId);
+    }
+
+    [Theory]
+    [InlineData("theme", "query", "")]
+    [InlineData("theme", "nxtSession", "preMarket")]
+    [InlineData("expert", "query", "")]
+    public void SelectTab_RejectsWebSuppliedInitialLoadParameters(
+        string tabId,
+        string extraName,
+        string extraValue)
+    {
+        var json = "{\"type\":\"select-tab\",\"payload\":{" +
+            $"\"tabId\":\"{tabId}\",\"{extraName}\":\"{extraValue}\"}}}}";
+
+        Assert.False(LegacyBridgeProtocol.TryParseIntent(json, out _, out _));
+    }
+}