feat(mission-control): custom tiles — open any console program as a tile

Programs are configured in Settings → Custom tiles and stored in ui.config.json.
A tile with a fixed folder starts on click; without one it offers a submenu of
home, the list folders and browse.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/ClaudeDo.Ui.Tests/ViewModels/MissionControlViewModelTests.cs

@@ -321,7 +321,7 @@ public class MissionControlViewModelTests : IDisposable
         Assert.Equal(4, vm.SessionTargets.Count);                 // home, browse, Alpha, VPS
         Assert.Contains("VPS", vm.SessionTargets[3].Label);
 
-        vm.SessionTargets[3].StartCommand.Execute(null);
+        vm.SessionTargets[3].StartCommand!.Execute(null);
         var pane = Assert.Single(vm.ConPtySessions);
         Assert.Equal("VPS", pane.DisplayTitle);
     }
@@ -339,7 +339,7 @@ public class MissionControlViewModelTests : IDisposable
 
         using var vm = BuildVm(new FakeWorker());
         var browsed = false;
-        vm.BrowseForSessionRequested = () => browsed = true;
+        vm.PickFolderAsync = () => { browsed = true; return Task.FromResult<string?>(null); };
 
         await vm.RefreshSessionTargetsAsync();
 
@@ -347,10 +347,65 @@ public class MissionControlViewModelTests : IDisposable
         Assert.Equal(4, vm.SessionTargets.Count);
         Assert.Equal(new[] { "Beta", "Alpha" }, vm.SessionTargets.Skip(2).Select(t => t.Label).ToArray());
 
-        vm.SessionTargets[1].StartCommand.Execute(null);
+        vm.SessionTargets[1].StartCommand!.Execute(null);
         Assert.True(browsed);
     }
 
+    [Fact]
+    public async Task RefreshSessionTargetsAsync_CustomTiles_FixedFolderStartsDirectly_EmptyFolderOffersFolderSubmenu()
+    {
+        await using (var db = NewContext())
+        {
+            db.Lists.Add(new ListEntity { Id = "L1", Name = "Alpha", WorkingDir = @"C:\repos\alpha", CreatedAt = DateTime.UtcNow });
+            await db.SaveChangesAsync();
+        }
+        var settings = new AppSettings { ConfigPath = Path.Combine(Path.GetTempPath(), Guid.NewGuid().ToString("n") + ".json") };
+        settings.CustomTiles.Add(new CustomTile { Name = "Shell", Program = "cmd", Folder = @"C:\" });
+        settings.CustomTiles.Add(new CustomTile { Name = "Git", Program = "cmd" });
+        var worker = new FakeWorker();
+        using var vm = new MissionControlViewModel(new TestDbFactory(NewContext), worker, new UsagePillViewModel(worker), settings);
+
+        await vm.RefreshSessionTargetsAsync();
+
+        // Home, browse, Alpha, then the two custom tiles.
+        var fixedTile = vm.SessionTargets[3];
+        var askTile = vm.SessionTargets[4];
+        Assert.NotNull(fixedTile.StartCommand);
+        Assert.Null(fixedTile.Children);
+        Assert.Null(askTile.StartCommand);
+        // Same folder choice as the top level: home, the list folders, then browse.
+        Assert.Equal(3, askTile.Children!.Count);
+        Assert.Equal("Alpha", askTile.Children[1].Label);
+
+        askTile.Children[1].StartCommand!.Execute(null);
+        var pane = Assert.Single(vm.ConPtySessions);
+        Assert.Equal("Git", pane.DisplayTitle);
+    }
+
+    [Fact]
+    public void CustomTile_SplitArgs_SplitsOnWhitespace_QuotesGroup()
+    {
+        Assert.Equal(new[] { "lenovo-server", "-p", "56789" }, CustomTile.SplitArgs("lenovo-server  -p 56789 "));
+        Assert.Equal(new[] { "-c", "git log --oneline", "" }, CustomTile.SplitArgs("-c \"git log --oneline\" \"\""));
+        Assert.Empty(CustomTile.SplitArgs(null));
+    }
+
+    [Fact]
+    public void AppSettings_CustomTiles_RoundTripThroughConfigFile()
+    {
+        var path = Path.Combine(Path.GetTempPath(), Guid.NewGuid().ToString("n") + ".json");
+        try
+        {
+            var settings = new AppSettings { ConfigPath = path };
+            settings.CustomTiles.Add(new CustomTile { Name = "Server", Program = "ssh", Arguments = "lenovo-server" });
+            settings.Save();
+
+            var tile = Assert.Single(AppSettings.Load(path).CustomTiles);
+            Assert.Equal(("Server", "ssh", "lenovo-server", ""), (tile.Name, tile.Program, tile.Arguments, tile.Folder));
+        }
+        finally { File.Delete(path); }
+    }
+
     private async Task SeedQueueAsync()
     {
         await using var db = NewContext();