feat: Claude Code 原生 Windows 通知（C# / .NET 10 + Avalonia 12）

为 Claude Code 提供原生 Windows toast 通知：点击跳回原窗口、切回 Windows
Terminal 标签、跨虚拟桌面、调用方图标、非阻塞投递；NativeAOT 单文件分发。

Notify/Ipc/IpcConstants.cs

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+namespace Notify.Ipc;
+
+internal static class IpcConstants
+{
+    // 保证 Host 单例的互斥量名（Local 级，按用户会话隔离）
+    public const string HostMutexName = "ClaudeCodeNotifyHost";
+}

Notify/Ipc/NotificationSpool.cs

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+using System;
+using System.Diagnostics;
+using System.IO;
+using System.Text.Json;
+using System.Threading;
+using Notify.Serialization;
+
+namespace Notify.Ipc;
+
+/// <summary>
+/// 基于落盘队列的非阻塞投递：CLI 写文件后立即返回，Host 监视目录消费
+///
+/// 取代命名管道，避免 CLI 在 Host 冷启动时被阻塞而拖住 Claude Code
+/// </summary>
+public static class NotificationSpool
+{
+    public static readonly string Dir =
+        Path.Combine(Path.GetTempPath(), "claude-notify-spool");
+
+    // CLI 侧：写入一条请求，必要时拉起 Host，全程不阻塞
+    public static void Deliver(NotifyMessage message)
+    {
+        try
+        {
+            Directory.CreateDirectory(Dir);
+
+            // 先写 .tmp 再原子改名为 .json，避免 Host 读到半截文件
+            var id = Guid.NewGuid().ToString("N");
+            var tmp = Path.Combine(Dir, id + ".tmp");
+            var final = Path.Combine(Dir, id + ".json");
+            File.WriteAllText(tmp, JsonSerializer.Serialize(message, AppJsonContext.Default.NotifyMessage));
+            File.Move(tmp, final);
+        }
+        catch
+        {
+            // 写入失败则放弃这条通知，绝不影响调用方
+        }
+
+        EnsureHostRunning();
+    }
+
+    // Host 未运行则拉起（不等待）；运行中则什么都不做
+    private static void EnsureHostRunning()
+    {
+        try
+        {
+            if (Mutex.TryOpenExisting(IpcConstants.HostMutexName, out var existing))
+            {
+                existing.Dispose();
+                return;
+            }
+        }
+        catch
+        {
+            // 打不开就当作未运行，继续尝试拉起
+        }
+
+        try
+        {
+            var exe = Environment.ProcessPath;
+            if (exe is null)
+            {
+                return;
+            }
+
+            // 必须用 UseShellExecute=true 让 host 彻底脱离本进程的标准句柄
+            // 否则常驻 host 会继承并攥住钩子的 stdout 管道，导致 Claude Code
+            // 等不到管道 EOF 而卡在 "running stop hook"
+            Process.Start(new ProcessStartInfo
+            {
+                FileName = exe,
+                Arguments = "host",
+                UseShellExecute = true,
+                WindowStyle = ProcessWindowStyle.Hidden,
+            });
+        }
+        catch
+        {
+            // 拉起失败则该通知会在下次 Host 启动时由 DrainExisting 补弹
+        }
+    }
+
+    // Host 侧：消费单个 spool 文件并删除
+    public static NotifyMessage? ReadAndRemove(string path)
+    {
+        try
+        {
+            var json = File.ReadAllText(path);
+            File.Delete(path);
+            return JsonSerializer.Deserialize(json, AppJsonContext.Default.NotifyMessage);
+        }
+        catch
+        {
+            return null;
+        }
+    }
+
+    // Host 启动时把已有的 spool 文件补弹一遍
+    public static void DrainExisting(Action<NotifyMessage> handler)
+    {
+        try
+        {
+            if (!Directory.Exists(Dir))
+            {
+                return;
+            }
+
+            foreach (var path in Directory.GetFiles(Dir, "*.json"))
+            {
+                if (ReadAndRemove(path) is { } msg)
+                {
+                    handler(msg);
+                }
+            }
+        }
+        catch
+        {
+            // 忽略
+        }
+    }
+}

Notify/Ipc/NotifyMessage.cs

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+namespace Notify.Ipc;
+
+/// <summary>
+/// 一条投递给 Host 的弹窗请求，经 spool 文件传递
+/// </summary>
+public sealed class NotifyMessage
+{
+    public string Title { get; set; } = "";
+
+    public string Message { get; set; } = "";
+
+    // true = 需要输入（青色边框）
+    public bool InputMode { get; set; }
+
+    // true = 常驻，不自动消失
+    public bool Sticky { get; set; }
+
+    // 触发该通知的会话 id
+    public string? SessionId { get; set; }
+
+    // 点击 toast 时要激活的目标窗口句柄，0 表示无
+    public long TargetHwnd { get; set; }
+
+    // 目标若为 Windows Terminal，激活后要切回的标签 RuntimeId
+    public string? WtRuntimeId { get; set; }
+
+    // 调用方 App 的 exe 路径，用于显示其图标
+    public string? IconPath { get; set; }
+}

Notify/Ipc/SpoolWatcher.cs

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+using System;
+using System.IO;
+
+namespace Notify.Ipc;
+
+/// <summary>
+/// Host 侧：监视 spool 目录，新文件出现即消费并回调
+/// </summary>
+public sealed class SpoolWatcher
+{
+    private readonly Action<NotifyMessage> _onMessage;
+    private FileSystemWatcher? _watcher;
+
+    public SpoolWatcher(Action<NotifyMessage> onMessage) => _onMessage = onMessage;
+
+    public void Start()
+    {
+        Directory.CreateDirectory(NotificationSpool.Dir);
+
+        // 先补弹启动前堆积的请求
+        NotificationSpool.DrainExisting(_onMessage);
+
+        _watcher = new FileSystemWatcher(NotificationSpool.Dir, "*.json")
+        {
+            NotifyFilter = NotifyFilters.FileName,
+            EnableRaisingEvents = true,
+        };
+        _watcher.Created += OnCreated;
+        _watcher.Renamed += OnRenamed;
+    }
+
+    private void OnCreated(object sender, FileSystemEventArgs e) => Handle(e.FullPath);
+
+    private void OnRenamed(object sender, RenamedEventArgs e) => Handle(e.FullPath);
+
+    private void Handle(string path)
+    {
+        if (NotificationSpool.ReadAndRemove(path) is { } msg)
+        {
+            _onMessage(msg);
+        }
+    }
+}