feat: add component infrastructure

- add focusable runtime state and invalidate entry

- add theme primitives and reusable components

- add component checks for focus and cancellation

TODO.md

@@ -225,6 +225,38 @@ TinyTUI 现在已经具备最小可运行的 C# TUI 框架骨架：终端输入
 
 参考：`tmp/tui/src/components/*`
 
+本次推进：
+
+- 新增 `IFocusableComponent`，把焦点状态从组件内部自管改成由 `TuiRuntime.SetFocus` 统一写入
+- `Input`、`SelectList`、`Editor` 改为只在 `Focused` 为 true 时输出 `CursorMarker`，避免多个可输入组件同时影响硬件光标定位
+- `TuiRuntime` 在添加、移除、焦点切换、resize 和显式 `Invalidate()` 时递归清理组件缓存，为主题变化和复杂组件缓存失效提供框架入口
+- `RenderPipelineOptions` 新增 `ShowHardwareCursor`，renderer 始终能把硬件光标定位到 marker，是否显示光标由配置或 `TINYTUI_HARDWARE_CURSOR` 控制
+- 新增 `ITuiTheme` 和默认 `TuiTheme`，先提供 hint、dim、输入光标、设置项标签和值、选择 cursor 等跨组件样式入口
+- 新增通用组件 `Spacer`、`TruncatedText`、`CancellableLoader`，覆盖空行间隔、ANSI 感知单行截断和 Escape 取消加载流程
+- 新增 `TinyTUI.ComponentChecks` 最小检查项目，验证 focusable marker、通用组件渲染和 cancellable loader 取消行为
+
+为什么先做：
+
+- `tmp/tui/src/tui.ts` 的 `Focusable.focused` 是组件基础设施的关键分界：运行时决定谁有焦点，组件只根据状态决定是否发出硬件光标 marker；先补这一层能减少后续 overlay、autocomplete、settings 子菜单抢焦点时的耦合
+- 主题和通用组件先提供薄接口和默认实现，不直接重写所有现有组件样式，避免一次提交同时改变大量视觉输出
+- `Invalidate()` 先接入 runtime 生命周期和 resize，不提前实现完整缓存系统，但给 Markdown、SettingsList、Autocomplete 这类后续复杂组件留下统一失效入口
+
+当前更好的点：
+
+- C# 侧通过 `IFocusableComponent` 明确焦点状态契约，运行时切换焦点时会同时 invalidate 前后组件，后续带缓存组件不需要自己猜测焦点变化
+- 硬件光标显示配置放在渲染管线选项里，组件只负责 marker，避免组件直接依赖终端输出细节
+- `CancellableLoader` 暴露标准 `CancellationToken`，比只暴露回调更容易接入 C# async 工作流
+- `TruncatedText` 直接复用 `ITextMeasurer`，能继承第 5 项已经补过的 ANSI、OSC 和 grapheme 宽度处理
+
+后续仍需补齐：
+
+- `SettingsList` 还没有移植，参考实现里的搜索、描述换行、值循环、submenu 委托和主题分区仍需单独推进
+- `ITuiTheme` 当前只是轻量样式接口，还没有 runtime 级主题持有、主题切换事件和组件缓存 theme version
+- `Input` 目前仍是尾部输入模型，还没有参考实现里的水平滚动、按 grapheme 移动、kill ring 和 undo；这些应在输入/编辑能力后续增量中处理
+- 组件缓存规范还只具备 invalidate 入口，没有统一的 width/content/theme cache key，也没有 Markdown AST 或复杂布局缓存基类
+- 焦点恢复策略仍比 `tmp/tui/src/tui.ts` 简化，overlay 被临时隐藏、非 overlay 组件短暂抢焦点和多层 submenu 的 blocked restore 还需要继续补强
+- 硬件光标定位已可配置显示隐藏，但还没有维护 renderer 级 `hardwareCursorRow` 相对移动模型，IME 在滚动和 resize 场景仍需要真实终端验证
+
 ### 7. 自动补全和命令交互基础
 
 目标：把自动补全从 Editor 局部功能升级为可复用的交互能力

src/TinyTUI/Components/CancellableLoader.cs

@@ -0,0 +1,72 @@
+using TinyTUI.Input;
+
+namespace TinyTUI.Components;
+
+/// <summary>
+/// 支持 Escape 取消并暴露 CancellationToken 的加载组件
+/// </summary>
+public sealed class CancellableLoader : IInputComponent, IDisposable
+{
+    private readonly KeybindingRegistry _keybindings;
+    private readonly CancellationTokenSource _cancellation = new();
+    private readonly Loader _loader;
+
+    /// <summary>
+    /// 创建可取消加载组件
+    /// </summary>
+    public CancellableLoader(Loader? loader = null, KeybindingRegistry? keybindings = null)
+    {
+        _loader = loader ?? new Loader();
+        _keybindings = keybindings ?? KeybindingRegistry.CreateDefault();
+    }
+
+    /// <summary>
+    /// 获取底层加载组件
+    /// </summary>
+    public Loader Loader => _loader;
+
+    /// <summary>
+    /// 获取用于传递给异步操作的取消令牌
+    /// </summary>
+    public CancellationToken Token => _cancellation.Token;
+
+    /// <summary>
+    /// 获取是否已经取消
+    /// </summary>
+    public bool IsCanceled => _cancellation.IsCancellationRequested;
+
+    /// <summary>
+    /// 在用户取消加载时触发
+    /// </summary>
+    public Action? OnCanceled { get; set; }
+
+    /// <inheritdoc />
+    public IReadOnlyList<string> Render(int width) => _loader.Render(width);
+
+    /// <inheritdoc />
+    public void Invalidate() => ((IComponent)_loader).Invalidate();
+
+    /// <inheritdoc />
+    public void HandleInput(TuiInputEvent input)
+    {
+        if (input.Kind != TuiInputEventKind.Key || !_keybindings.Matches(input, TuiKeybindings.SelectCancel))
+            return;
+
+        Cancel();
+    }
+
+    /// <summary>
+    /// 手动取消加载流程
+    /// </summary>
+    public void Cancel()
+    {
+        if (IsCanceled)
+            return;
+
+        _cancellation.Cancel();
+        OnCanceled?.Invoke();
+    }
+
+    /// <inheritdoc />
+    public void Dispose() => _cancellation.Dispose();
+}

src/TinyTUI/Components/Core/IFocusableComponent.cs

@@ -0,0 +1,12 @@
+namespace TinyTUI.Components;
+
+/// <summary>
+/// 定义可由运行时统一设置焦点状态的组件
+/// </summary>
+public interface IFocusableComponent : IComponent
+{
+    /// <summary>
+    /// 获取或设置组件当前是否拥有输入焦点
+    /// </summary>
+    bool Focused { get; set; }
+}

src/TinyTUI/Components/Editor/Editor.Rendering.cs

@@ -101,13 +101,16 @@ public sealed partial class Editor
     private string RenderVisualRow(EditorVisualRow row, bool isLastRow)
     {
         if (IsEmpty && row.LogicalRow == _cursorRow && Placeholder.Length > 0)
-            return CursorMarker.Marker + _textMeasurer.Truncate(Placeholder, _lastRenderWidth);
+        {
+            var marker = Focused ? CursorMarker.Marker : string.Empty;
+            return marker + _textMeasurer.Truncate(Placeholder, _lastRenderWidth);
+        }
 
         if (row.LogicalRow != _cursorRow || !IsCursorInVisualRow(row, isLastRow))
             return row.Text;
 
         // Renderer 会提取这个 marker 并移动硬件光标 所以这里不渲染可见光标字符
-        return InsertCursorMarker(row.Text, _cursorColumn - row.StartColumn);
+        return Focused ? InsertCursorMarker(row.Text, _cursorColumn - row.StartColumn) : row.Text;
     }
 
     /// <summary>

src/TinyTUI/Components/Editor/Editor.cs

@@ -6,7 +6,7 @@ namespace TinyTUI.Components;
 /// <summary>
 /// 支持多行文本编辑的基础编辑器组件
 /// </summary>
-public sealed partial class Editor(ITextMeasurer? textMeasurer = null, KeybindingRegistry? keybindings = null) : IInputComponent
+public sealed partial class Editor(ITextMeasurer? textMeasurer = null, KeybindingRegistry? keybindings = null) : IInputComponent, IFocusableComponent
 {
     private readonly ITextMeasurer _textMeasurer = textMeasurer ?? new TerminalTextMeasurer();
     private readonly KeybindingRegistry _keybindings = keybindings ?? KeybindingRegistry.CreateDefault();
@@ -38,6 +38,9 @@ public sealed partial class Editor(ITextMeasurer? textMeasurer = null, Keybindin
     /// </summary>
     public string Placeholder { get; set; } = string.Empty;
 
+    /// <inheritdoc />
+    public bool Focused { get; set; }
+
     /// <summary>
     /// 获取当前编辑器文本
     /// </summary>

src/TinyTUI/Components/Input.cs

@@ -2,16 +2,21 @@ using System.Text;
 using TinyTUI.Input;
 using TinyTUI.Rendering;
 using TinyTUI.Text;
+using TinyTUI.Theme;
 
 namespace TinyTUI.Components;
 
 /// <summary>
 /// 支持文本输入 提交和取消的单行输入组件
 /// </summary>
-public sealed class Input(ITextMeasurer? textMeasurer = null, KeybindingRegistry? keybindings = null) : IInputComponent
+public sealed class Input(
+    ITextMeasurer? textMeasurer = null,
+    KeybindingRegistry? keybindings = null,
+    ITuiTheme? theme = null) : IInputComponent, IFocusableComponent
 {
     private readonly ITextMeasurer _textMeasurer = textMeasurer ?? new TerminalTextMeasurer();
     private readonly KeybindingRegistry _keybindings = keybindings ?? KeybindingRegistry.CreateDefault();
+    private readonly ITuiTheme _theme = theme ?? TuiTheme.Default;
 
     /// <summary>
     /// 获取或设置输入框前缀
@@ -23,6 +28,9 @@ public sealed class Input(ITextMeasurer? textMeasurer = null, KeybindingRegistry
     /// </summary>
     public string Value { get; private set; } = string.Empty;
 
+    /// <inheritdoc />
+    public bool Focused { get; set; }
+
     /// <summary>
     /// 在输入值变化时触发
     /// </summary>
@@ -41,8 +49,10 @@ public sealed class Input(ITextMeasurer? textMeasurer = null, KeybindingRegistry
     /// <inheritdoc />
     public IReadOnlyList<string> Render(int width)
     {
-        // 光标不渲染成可见字符 由 renderer 提取 marker 后移动真实终端光标
-        var visible = $"{Prompt}{Value}{CursorMarker.Marker}";
+        // 只有运行时确认获得焦点后才发出 marker 避免多个输入组件争抢硬件光标
+        var marker = Focused ? CursorMarker.Marker : string.Empty;
+        var cursor = Focused ? _theme.InputCursor(" ") : string.Empty;
+        var visible = $"{Prompt}{Value}{marker}{cursor}";
         return [_textMeasurer.Truncate(visible, width)];
     }
 

src/TinyTUI/Components/SelectList.cs

@@ -1,19 +1,24 @@
 using TinyTUI.Input;
 using TinyTUI.Rendering;
 using TinyTUI.Text;
+using TinyTUI.Theme;
 
 namespace TinyTUI.Components;
 
 /// <summary>
 /// 支持方向键选择和回车确认的列表组件
 /// </summary>
-public sealed class SelectList(ITextMeasurer? textMeasurer = null, KeybindingRegistry? keybindings = null) : IInputComponent
+public sealed class SelectList(
+    ITextMeasurer? textMeasurer = null,
+    KeybindingRegistry? keybindings = null,
+    ITuiTheme? theme = null) : IInputComponent, IFocusableComponent
 {
     private const int PrimaryColumnGap = 2;
     private const int MinDescriptionWidth = 10;
 
     private readonly ITextMeasurer _textMeasurer = textMeasurer ?? new TerminalTextMeasurer();
     private readonly KeybindingRegistry _keybindings = keybindings ?? KeybindingRegistry.CreateDefault();
+    private readonly ITuiTheme _theme = theme ?? TuiTheme.Default;
     private readonly List<SelectItem> _items = [];
     private readonly List<SelectItem> _filteredItems = [];
 
@@ -29,6 +34,9 @@ public sealed class SelectList(ITextMeasurer? textMeasurer = null, KeybindingReg
     /// </summary>
     public int SelectedIndex { get; private set; }
 
+    /// <inheritdoc />
+    public bool Focused { get; set; }
+
     /// <summary>
     /// 获取当前选中项文本
     /// </summary>
@@ -114,8 +122,9 @@ public sealed class SelectList(ITextMeasurer? textMeasurer = null, KeybindingReg
     public IReadOnlyList<string> Render(int width)
     {
         var lines = new List<string>();
+        var marker = Focused ? CursorMarker.Marker : string.Empty;
 
-        lines.Add(_textMeasurer.Truncate($"Filter: {_filter}{CursorMarker.Marker}", width));
+        lines.Add(_textMeasurer.Truncate($"Filter: {_filter}{marker}", width));
 
         if (_filteredItems.Count == 0)
         {
@@ -244,7 +253,7 @@ public sealed class SelectList(ITextMeasurer? textMeasurer = null, KeybindingReg
     /// </summary>
     private string RenderItem(SelectItem item, bool selected, int width, int primaryWidth)
     {
-        var prefix = selected ? "> " : "  ";
+        var prefix = selected ? _theme.Cursor : "  ";
         var label = NormalizeSingleLine(item.Label.Length == 0 ? item.Value : item.Label);
         var description = NormalizeSingleLine(item.Description ?? string.Empty);
         var prefixWidth = _textMeasurer.GetWidth(prefix);

src/TinyTUI/Components/Spacer.cs

@@ -0,0 +1,19 @@
+namespace TinyTUI.Components;
+
+/// <summary>
+/// 渲染固定数量空行的间隔组件
+/// </summary>
+public sealed class Spacer(int lines = 1) : IComponent
+{
+    /// <summary>
+    /// 获取或设置空行数量
+    /// </summary>
+    public int Lines { get; set; } = Math.Max(0, lines);
+
+    /// <inheritdoc />
+    public IReadOnlyList<string> Render(int width)
+    {
+        var count = Math.Max(0, Lines);
+        return count == 0 ? [] : Enumerable.Repeat(string.Empty, count).ToArray();
+    }
+}

src/TinyTUI/Components/TruncatedText.cs

@@ -0,0 +1,68 @@
+using TinyTUI.Text;
+
+namespace TinyTUI.Components;
+
+/// <summary>
+/// 渲染单行并按终端宽度截断和填充的文本组件
+/// </summary>
+public sealed class TruncatedText(string value = "", ITextMeasurer? textMeasurer = null) : IComponent
+{
+    private readonly ITextMeasurer _textMeasurer = textMeasurer ?? new TerminalTextMeasurer();
+
+    /// <summary>
+    /// 获取或设置要显示的文本
+    /// </summary>
+    public string Value { get; set; } = value;
+
+    /// <summary>
+    /// 获取或设置左右内边距
+    /// </summary>
+    public int PaddingX { get; set; }
+
+    /// <summary>
+    /// 获取或设置上下空行内边距
+    /// </summary>
+    public int PaddingY { get; set; }
+
+    /// <summary>
+    /// 获取或设置是否补齐到完整宽度
+    /// </summary>
+    public bool PadToWidth { get; set; } = true;
+
+    /// <inheritdoc />
+    public IReadOnlyList<string> Render(int width)
+    {
+        var safeWidth = Math.Max(0, width);
+        var lines = new List<string>();
+        var emptyLine = PadToWidth ? new string(' ', safeWidth) : string.Empty;
+        var paddingY = Math.Max(0, PaddingY);
+
+        for (var index = 0; index < paddingY; index++)
+            lines.Add(emptyLine);
+
+        lines.Add(RenderContentLine(safeWidth));
+
+        for (var index = 0; index < paddingY; index++)
+            lines.Add(emptyLine);
+
+        return lines;
+    }
+
+    /// <summary>
+    /// 渲染单行内容并按可用宽度处理左右内边距
+    /// </summary>
+    private string RenderContentLine(int width)
+    {
+        var paddingX = Math.Max(0, PaddingX);
+        var availableWidth = Math.Max(0, width - paddingX * 2);
+        var singleLine = Value.Replace("\r\n", "\n").Split('\n')[0];
+        var content = availableWidth == 0 ? string.Empty : _textMeasurer.Truncate(singleLine, availableWidth);
+        var rendered = $"{new string(' ', paddingX)}{content}{new string(' ', paddingX)}";
+
+        if (!PadToWidth)
+            return rendered;
+
+        var padding = Math.Max(0, width - _textMeasurer.GetWidth(rendered));
+        return rendered + new string(' ', padding);
+    }
+}

src/TinyTUI/Rendering/DifferentialRenderer.cs

@@ -252,14 +252,24 @@ public sealed class DifferentialRenderer : IRenderer
     private void MoveCursor(RenderedFrame frame)
     {
         if (frame.Cursor is not { } position)
+        {
+            _output.HideCursor();
             return;
+        }
 
         var visibleRow = position.Row - frame.Viewport.Top;
         if (visibleRow is < 1 || visibleRow > frame.Viewport.Height)
+        {
+            _output.HideCursor();
             return;
+        }
 
-        _output.ShowCursor();
         _output.MoveCursorTo(visibleRow, position.Column);
+
+        if (_options.ShowHardwareCursor)
+            _output.ShowCursor();
+        else
+            _output.HideCursor();
     }
 
     /// <summary>

src/TinyTUI/Rendering/FullScreenRenderer.cs

@@ -77,13 +77,23 @@ public sealed class FullScreenRenderer : IRenderer
     private void MoveCursor(RenderedFrame frame)
     {
         if (frame.Cursor is not { } position)
+        {
+            _output.HideCursor();
             return;
+        }
 
         var visibleRow = position.Row - frame.Viewport.Top;
         if (visibleRow is < 1 || visibleRow > frame.Viewport.Height)
+        {
+            _output.HideCursor();
             return;
+        }
 
-        _output.ShowCursor();
         _output.MoveCursorTo(visibleRow, position.Column);
+
+        if (_options.ShowHardwareCursor)
+            _output.ShowCursor();
+        else
+            _output.HideCursor();
     }
 }

src/TinyTUI/Rendering/RenderPipelineOptions.cs

@@ -30,6 +30,11 @@ public sealed class RenderPipelineOptions
     /// </summary>
     public bool ThrowOnWidthOverflow { get; init; }
 
+    /// <summary>
+    /// 获取或设置定位到光标标记后是否显示硬件光标
+    /// </summary>
+    public bool ShowHardwareCursor { get; init; } = Environment.GetEnvironmentVariable("TINYTUI_HARDWARE_CURSOR") == "1";
+
     /// <summary>
     /// 获取或设置是否写出每次差分渲染调试日志
     /// </summary>

src/TinyTUI/Runtime/ITuiRuntime.cs

@@ -23,6 +23,11 @@ public interface ITuiRuntime : IDisposable
     /// </summary>
     void SetFocus(IComponent? component);
 
+    /// <summary>
+    /// 递归清除组件缓存并请求重新渲染
+    /// </summary>
+    void Invalidate();
+
     /// <summary>
     /// 请求一次渲染
     /// </summary>

src/TinyTUI/Runtime/TuiRuntime.cs

@@ -46,6 +46,7 @@ public sealed class TuiRuntime : ITuiRuntime
     public void Add(IComponent component)
     {
         _root.Add(component);
+        component.Invalidate();
         RequestRender();
     }
 
@@ -54,13 +55,37 @@ public sealed class TuiRuntime : ITuiRuntime
     {
         _root.Remove(component);
 
-        if (_focusedComponent == component) _focusedComponent = null;
+        if (_focusedComponent == component)
+            SetFocus(null);
+        else
+            component.Invalidate();
 
         RequestRender();
     }
 
     /// <inheritdoc />
-    public void SetFocus(IComponent? component) => _focusedComponent = component;
+    public void SetFocus(IComponent? component)
+    {
+        if (ReferenceEquals(_focusedComponent, component))
+            return;
+
+        SetFocusableState(_focusedComponent, focused: false);
+        _focusedComponent?.Invalidate();
+
+        _focusedComponent = component;
+
+        SetFocusableState(_focusedComponent, focused: true);
+        _focusedComponent?.Invalidate();
+
+        RequestRender();
+    }
+
+    /// <inheritdoc />
+    public void Invalidate()
+    {
+        _root.Invalidate();
+        RequestRender();
+    }
 
     /// <inheritdoc />
     public void RequestRender()
@@ -142,7 +167,10 @@ public sealed class TuiRuntime : ITuiRuntime
     }
 
     private void OnResized(object? sender, TerminalSize size)
-        => Dispatch(new TuiInputEvent(TuiInputEventKind.Resize, $"{size.Columns}x{size.Rows}"));
+    {
+        _root.Invalidate();
+        Dispatch(new TuiInputEvent(TuiInputEventKind.Resize, $"{size.Columns}x{size.Rows}"));
+    }
 
     /// <summary>
     /// 将输入事件发送给当前焦点组件并请求重渲染
@@ -200,7 +228,16 @@ public sealed class TuiRuntime : ITuiRuntime
             _overlayFocusRestore.TryGetValue(component, out restoreFocus);
 
         if (_focusedComponent == component)
-            _focusedComponent = _overlayManager.TopFocusableComponent ?? restoreFocus;
+            SetFocus(_overlayManager.TopFocusableComponent ?? restoreFocus);
+    }
+
+    /// <summary>
+    /// 统一写入组件焦点状态 组件自身只根据状态决定是否输出光标 marker
+    /// </summary>
+    private static void SetFocusableState(IComponent? component, bool focused)
+    {
+        if (component is IFocusableComponent focusable)
+            focusable.Focused = focused;
     }
 
     /// <summary>

src/TinyTUI/Theme/ITuiTheme.cs

@@ -0,0 +1,37 @@
+namespace TinyTUI.Theme;
+
+/// <summary>
+/// 定义组件渲染时可复用的终端样式入口
+/// </summary>
+public interface ITuiTheme
+{
+    /// <summary>
+    /// 获取普通提示文本样式
+    /// </summary>
+    string Hint(string value);
+
+    /// <summary>
+    /// 获取弱化文本样式
+    /// </summary>
+    string Dim(string value);
+
+    /// <summary>
+    /// 获取选中行前缀
+    /// </summary>
+    string Cursor { get; }
+
+    /// <summary>
+    /// 获取输入光标所在字符样式
+    /// </summary>
+    string InputCursor(string value);
+
+    /// <summary>
+    /// 获取设置项标签样式
+    /// </summary>
+    string SettingLabel(string value, bool selected);
+
+    /// <summary>
+    /// 获取设置项值样式
+    /// </summary>
+    string SettingValue(string value, bool selected);
+}

src/TinyTUI/Theme/TuiTheme.cs

@@ -0,0 +1,30 @@
+namespace TinyTUI.Theme;
+
+/// <summary>
+/// 提供 TinyTUI 默认终端主题
+/// </summary>
+public sealed class TuiTheme : ITuiTheme
+{
+    /// <summary>
+    /// 获取默认主题实例
+    /// </summary>
+    public static TuiTheme Default { get; } = new();
+
+    /// <inheritdoc />
+    public string Cursor { get; init; } = "> ";
+
+    /// <inheritdoc />
+    public string Hint(string value) => $"\e[2m{value}\e[22m";
+
+    /// <inheritdoc />
+    public string Dim(string value) => $"\e[2m{value}\e[22m";
+
+    /// <inheritdoc />
+    public string InputCursor(string value) => $"\e[7m{value}\e[27m";
+
+    /// <inheritdoc />
+    public string SettingLabel(string value, bool selected) => selected ? $"\e[1m{value}\e[22m" : value;
+
+    /// <inheritdoc />
+    public string SettingValue(string value, bool selected) => selected ? $"\e[36m{value}\e[39m" : value;
+}

test/TinyTUI.ComponentChecks/Program.cs

@@ -0,0 +1,58 @@
+using TinyTUI.Components;
+using TinyTUI.Input;
+using TinyTUI.Rendering;
+using TinyTUI.Text;
+
+var measurer = new TerminalTextMeasurer();
+
+var input = new Input(measurer) { Prompt = "> " };
+AssertFalse(input.Render(20)[0].Contains(CursorMarker.Marker, StringComparison.Ordinal), "unfocused input marker");
+input.Focused = true;
+AssertTrue(input.Render(20)[0].Contains(CursorMarker.Marker, StringComparison.Ordinal), "focused input marker");
+
+var editor = new Editor(measurer) { Placeholder = "type here" };
+AssertFalse(editor.Render(20)[0].Contains(CursorMarker.Marker, StringComparison.Ordinal), "unfocused editor marker");
+editor.Focused = true;
+AssertTrue(editor.Render(20)[0].Contains(CursorMarker.Marker, StringComparison.Ordinal), "focused editor marker");
+
+var list = new SelectList(measurer);
+list.SetItems(["alpha", "beta"]);
+AssertFalse(list.Render(20)[0].Contains(CursorMarker.Marker, StringComparison.Ordinal), "unfocused select marker");
+list.Focused = true;
+AssertTrue(list.Render(20)[0].Contains(CursorMarker.Marker, StringComparison.Ordinal), "focused select marker");
+
+AssertEqual(3, new Spacer(3).Render(10).Count, "spacer line count");
+AssertEqual(0, new Spacer(-1).Render(10).Count, "spacer clamps negative lines");
+
+var truncated = new TruncatedText("abcdef\nignored", measurer)
+{
+    PaddingX = 1,
+    PaddingY = 1,
+};
+var truncatedLines = truncated.Render(6);
+AssertEqual(3, truncatedLines.Count, "truncated text vertical padding");
+AssertEqual(6, measurer.GetWidth(truncatedLines[1]), "truncated text padded width");
+AssertTrue(truncatedLines[1].Contains("abc", StringComparison.Ordinal), "truncated text first line only");
+
+var loader = new CancellableLoader(keybindings: KeybindingRegistry.CreateDefault());
+var canceled = false;
+loader.OnCanceled = () => canceled = true;
+loader.HandleInput(new TuiInputEvent(TuiInputEventKind.Key, KeyNames.Escape));
+AssertTrue(loader.IsCanceled, "cancellable loader token");
+AssertTrue(canceled, "cancellable loader callback");
+
+Console.WriteLine("TinyTUI component checks passed");
+
+static void AssertEqual<T>(T expected, T actual, string name)
+{
+    if (!EqualityComparer<T>.Default.Equals(expected, actual))
+        throw new InvalidOperationException($"{name}: expected '{expected}', actual '{actual}'");
+}
+
+static void AssertTrue(bool condition, string name)
+{
+    if (!condition)
+        throw new InvalidOperationException($"{name}: assertion failed");
+}
+
+static void AssertFalse(bool condition, string name) => AssertTrue(!condition, name);

test/TinyTUI.ComponentChecks/TinyTUI.ComponentChecks.csproj

@@ -0,0 +1,14 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <ItemGroup>
+    <ProjectReference Include="..\..\src\TinyTUI\TinyTUI.csproj" />
+  </ItemGroup>
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net10.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+
+</Project>

ttui.slnx

@@ -9,5 +9,6 @@
   </Folder>
   <Project Path="src/Example/Example.csproj" Id="6656c1ec-b220-4e7a-8875-5a97a85afbc1" />
   <Project Path="src/TinyTUI/TinyTUI.csproj" Id="f39199aa-6947-4951-b952-a1588045505e" />
+  <Project Path="test/TinyTUI.ComponentChecks/TinyTUI.ComponentChecks.csproj" Id="95c72f97-61f0-4806-8a90-28d70a89cd87" />
   <Project Path="test/TinyTUI.TextChecks/TinyTUI.TextChecks.csproj" Id="d827983c-78a1-4f04-85f3-874ccfe2e735" />
 </Solution>