diff --git a/src/c#/GeneralUpdate.Core/FileSystem/StorageManager.cs b/src/c#/GeneralUpdate.Core/FileSystem/StorageManager.cs
index d0143d28..e04b4f06 100644
--- a/src/c#/GeneralUpdate.Core/FileSystem/StorageManager.cs
+++ b/src/c#/GeneralUpdate.Core/FileSystem/StorageManager.cs
@@ -283,6 +283,62 @@ private IEnumerable<FileNode> ReadFileNode(string path, string rootPath = null)
 
         private void ResetId() => Interlocked.Exchange(ref _fileCount, 0);
 
+        /// <summary>Restore files from backup directory to install path.</summary>
+        public static void Restore(string backupDir, string installPath)
+        {
+            if (!Directory.Exists(backupDir))
+                throw new DirectoryNotFoundException($"Backup directory not found: {backupDir}");
+
+            foreach (var file in Directory.GetFiles(backupDir, "*", SearchOption.AllDirectories))
+            {
+                var relativePath = file.Substring(backupDir.Length).TrimStart(Path.DirectorySeparatorChar);
+                var dest = Path.Combine(installPath, relativePath);
+                Directory.CreateDirectory(Path.GetDirectoryName(dest)!);
+                File.Copy(file, dest, true);
+            }
+        }
+
+        /// <summary>Clean old backups, keeping only the N most recent versions.</summary>
+        public static void CleanBackup(string installPath, int keepVersions = 3)
+        {
+            var backupRoot = Path.Combine(installPath, "__backups");
+            if (!Directory.Exists(backupRoot)) return;
+
+            var dirs = Directory.GetDirectories(backupRoot)
+                .Select(d => new DirectoryInfo(d))
+                .OrderByDescending(d => d.CreationTime)
+                .Skip(keepVersions);
+
+            foreach (var dir in dirs)
+                dir.Delete(true);
+        }
+
+        /// <summary>List backup versions with metadata.</summary>
+        public static IReadOnlyList<BackupInfo> ListBackups(string installPath)
+        {
+            var backupRoot = Path.Combine(installPath, "__backups");
+            if (!Directory.Exists(backupRoot)) return Array.Empty<BackupInfo>();
+
+            return Directory.GetDirectories(backupRoot)
+                .Select(d => new DirectoryInfo(d))
+                .Select(d => new BackupInfo(
+                    d.Name, d.FullName, d.CreationTime,
+                    d.GetFiles("*", SearchOption.AllDirectories).Sum(f => f.Length)))
+                .ToList();
+        }
+
         #endregion
     }
+
+    /// <summary>Backup configuration.</summary>
+    public sealed class BackupConfig
+    {
+        public int KeepVersions { get; set; } = 3;
+        public string? BackupRoot { get; set; }
+        public List<string> SkipDirectories { get; set; } = new();
+        public bool Enabled { get; set; } = true;
+    }
+
+    /// <summary>Backup metadata.</summary>
+    public record BackupInfo(string Version, string Path, DateTime CreatedAt, long SizeBytes);
 }
\ No newline at end of file
diff --git a/src/c#/GeneralUpdate.Core/Hooks/IUpdateHooks.cs b/src/c#/GeneralUpdate.Core/Hooks/IUpdateHooks.cs
new file mode 100644
index 00000000..55ee7e2c
--- /dev/null
+++ b/src/c#/GeneralUpdate.Core/Hooks/IUpdateHooks.cs
@@ -0,0 +1,84 @@
+using System;
+using System.Diagnostics;
+using System.IO;
+using System.Threading.Tasks;
+using GeneralUpdate.Core.Configuration;
+
+namespace GeneralUpdate.Core.Hooks;
+
+/// <summary>Lifecycle hooks for update processes.</summary>
+public interface IUpdateHooks
+{
+    Task<bool> OnBeforeUpdateAsync(UpdateContext ctx);
+    Task OnDownloadCompletedAsync(DownloadContext ctx);
+    Task OnAfterUpdateAsync(UpdateContext ctx);
+    Task OnUpdateErrorAsync(UpdateContext ctx, Exception ex);
+    Task OnBeforeStartAppAsync(UpdateContext ctx);
+}
+
+public record UpdateContext(
+    string AppName,
+    string InstallPath,
+    string CurrentVersion,
+    string? TargetVersion,
+    int AppType
+);
+
+public record DownloadContext(
+    string AssetName,
+    string Version,
+    long TotalBytes,
+    TimeSpan Duration,
+    string? LocalPath,
+    bool Success
+);
+
+/// <summary>Default no-op hooks.</summary>
+public class NoOpUpdateHooks : IUpdateHooks
+{
+    public Task<bool> OnBeforeUpdateAsync(UpdateContext ctx) => Task.FromResult(true);
+    public Task OnDownloadCompletedAsync(DownloadContext ctx) => Task.CompletedTask;
+    public Task OnAfterUpdateAsync(UpdateContext ctx) => Task.CompletedTask;
+    public Task OnUpdateErrorAsync(UpdateContext ctx, Exception ex) => Task.CompletedTask;
+    public Task OnBeforeStartAppAsync(UpdateContext ctx) => Task.CompletedTask;
+}
+
+/// <summary>Unix permission hooks — chmod +x main app before start.</summary>
+public class UnixPermissionHooks : IUpdateHooks
+{
+    public async Task OnBeforeStartAppAsync(UpdateContext ctx)
+    {
+        var mainApp = Path.Combine(ctx.InstallPath, ctx.AppName);
+        if (File.Exists(mainApp))
+            await Process.Start("chmod", $"+x \"{mainApp}\"").WaitForExitAsync();
+    }
+    public Task<bool> OnBeforeUpdateAsync(UpdateContext ctx) => Task.FromResult(true);
+    public Task OnDownloadCompletedAsync(DownloadContext ctx) => Task.CompletedTask;
+    public Task OnAfterUpdateAsync(UpdateContext ctx) => Task.CompletedTask;
+    public Task OnUpdateErrorAsync(UpdateContext ctx, Exception ex) => Task.CompletedTask;
+}
+
+/// <summary>User-supplied permission script hook.</summary>
+public class CustomPermissionHooks : IUpdateHooks
+{
+    private readonly string _scriptPath;
+    public CustomPermissionHooks(string scriptPath)
+        => _scriptPath = scriptPath ?? throw new ArgumentNullException(nameof(scriptPath));
+
+    public async Task OnBeforeStartAppAsync(UpdateContext ctx)
+    {
+        var psi = new ProcessStartInfo(_scriptPath, ctx.InstallPath)
+        {
+            RedirectStandardOutput = true, RedirectStandardError = true
+        };
+        using var proc = Process.Start(psi)!;
+        await proc.WaitForExitAsync();
+        if (proc.ExitCode != 0)
+            throw new InvalidOperationException(
+                $"Permission script '{_scriptPath}' failed (exit {proc.ExitCode})");
+    }
+    public Task<bool> OnBeforeUpdateAsync(UpdateContext ctx) => Task.FromResult(true);
+    public Task OnDownloadCompletedAsync(DownloadContext ctx) => Task.CompletedTask;
+    public Task OnAfterUpdateAsync(UpdateContext ctx) => Task.CompletedTask;
+    public Task OnUpdateErrorAsync(UpdateContext ctx, Exception ex) => Task.CompletedTask;
+}