feat(mosstank): add VTank-style automation PoC

tests/AcDream.UI.Abstractions.Tests/Panels/Chat/ChatCommandRouterTests.cs

@@ -7,6 +7,23 @@ namespace AcDream.UI.Abstractions.Tests.Panels.Chat;
 
 public class ChatCommandRouterTests
 {
+    [Fact]
+    public void PluginCommand_IsHandledBeforeUnknownServerFallback()
+    {
+        var (vm, _, inner) = Fixture();
+        var bus = new PluginCommandBus(inner);
+
+        SubmitOutcome outcome = ChatCommandRouter.Submit(
+            "/vt start",
+            vm,
+            bus,
+            ChatChannelKind.Say);
+
+        Assert.Equal(SubmitOutcome.ClientHandled, outcome);
+        Assert.Equal("/vt start", bus.Handled);
+        Assert.Empty(inner.Published);
+    }
+
     private sealed class CaptureBus : ICommandBus
     {
         public List<object> Published { get; } = new();
@@ -15,6 +32,21 @@ public class ChatCommandRouterTests
             => Published.Add(command);
     }
 
+    private sealed class PluginCommandBus(CaptureBus inner)
+        : IPluginCommandBus
+    {
+        public string? Handled { get; private set; }
+
+        public bool TryHandlePluginCommand(string commandLine)
+        {
+            Handled = commandLine;
+            return true;
+        }
+
+        public void Publish<T>(T command) where T : notnull =>
+            inner.Publish(command);
+    }
+
     private static (ChatVM vm, ChatLog log, CaptureBus bus) Fixture()
     {
         var log = new ChatLog();