diff --git a/backend/src/MoShiro.Backend.Application/ApplicationServiceCollectionExtensions.cs b/backend/src/MoShiro.Backend.Application/ApplicationServiceCollectionExtensions.cs
index 8471ccb..1e0a1bc 100644
--- a/backend/src/MoShiro.Backend.Application/ApplicationServiceCollectionExtensions.cs
+++ b/backend/src/MoShiro.Backend.Application/ApplicationServiceCollectionExtensions.cs
@@ -52,6 +52,8 @@ public static class ApplicationServiceCollectionExtensions
         services.AddSingleton<ReleaseService>();
         services.AddSingleton<ScheduleService>();
         services.AddSingleton<BackendUpdates>();
+        services.AddSingleton<BackendAutoUpdater>();
+        services.AddHostedService(provider => provider.GetRequiredService<BackendAutoUpdater>());
         services.AddSingleton<JoinTokenService>();
         services.AddSingleton<RawBrowserService>();
         services.AddSingleton<EventService>();
diff --git a/backend/src/MoShiro.Backend.Application/BackendOptions.cs b/backend/src/MoShiro.Backend.Application/BackendOptions.cs
index 603272e..2d4617e 100644
--- a/backend/src/MoShiro.Backend.Application/BackendOptions.cs
+++ b/backend/src/MoShiro.Backend.Application/BackendOptions.cs
@@ -21,6 +21,15 @@ public sealed class BackendOptions
     /// </summary>
     public string? UpdateMode { get; set; } = Environment.GetEnvironmentVariable("MOSHIRO_UPDATE");
 
+    /// <summary>
+    /// 自动更新（环境变量 <c>MoShiro__AutoUpdate=true</c>）：新版本登记之后过了 <see cref="AutoUpdateDelayMinutes"/> 分钟自动确认，和管理员点「更新并重启」是同一条路径
+    /// （先备份数据库，备份失败就不更新）。默认关：Backend 重启会让所有节点断一两分钟。同样需要 <see cref="UpdateMode"/> 是 <c>restart</c>。
+    /// </summary>
+    public bool AutoUpdate { get; set; }
+
+    /// <summary>新版本登记之后等多久再自动更新（分钟）：连着推几次的时候只更新到最后一版，也给 CI 里同时发布的 Agent 版本留出时间。</summary>
+    public int AutoUpdateDelayMinutes { get; set; } = 10;
+
     /// <summary>
     /// 每个 Agent 都必须有属主（passkey）：创建加入码时必须已经建立信任根，并且至少选一把操作员集合里的 passkey 作为属主。
     /// 属主是节点敏感内容（extension 会话、加密数据）绑定的人，装上时固定在节点本地，面板改不了。默认开；没有信任根的老部署才需要关掉。
diff --git a/backend/src/MoShiro.Backend.Application/Updates/BackendAutoUpdater.cs b/backend/src/MoShiro.Backend.Application/Updates/BackendAutoUpdater.cs
new file mode 100644
index 0000000..95ca8ba
--- /dev/null
+++ b/backend/src/MoShiro.Backend.Application/Updates/BackendAutoUpdater.cs
@@ -0,0 +1,100 @@
+using Microsoft.Extensions.Hosting;
+using Microsoft.Extensions.Logging;
+using MoShiro.Protocol;
+
+namespace MoShiro.Backend.Application;
+
+/// <summary>
+/// 自动更新（<see cref="BackendOptions.AutoUpdate"/>，默认关）：每分钟看一眼面板上登记的 Backend 新版本，登记满 <see cref="BackendOptions.AutoUpdateDelayMinutes"/> 分钟之后
+/// 替管理员确认。确认走 <see cref="BackendUpdates.ConfirmAsync"/>，所以数据库备份、清单签名、「只更新到登记时的那一版」都和手动更新一样；
+/// 更新是有序退出，由 Quadlet 单元（<c>Pull=always</c>、<c>Restart=always</c>）拉起新镜像。
+/// </summary>
+public sealed partial class BackendAutoUpdater : BackgroundService
+{
+    private static readonly TimeSpan s_startupDelay = TimeSpan.FromMinutes(2);
+    private static readonly TimeSpan s_interval = TimeSpan.FromMinutes(1);
+
+    private readonly BackendUpdates _updates;
+    private readonly BackendOptions _options;
+    private readonly TimeProvider _time;
+    private readonly ILogger<BackendAutoUpdater> _log;
+
+    public BackendAutoUpdater(BackendUpdates updates, BackendOptions options, TimeProvider time, ILogger<BackendAutoUpdater> log)
+    {
+        _updates = updates;
+        _options = options;
+        _time = time;
+        _log = log;
+    }
+
+    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
+    {
+        if (!_options.AutoUpdate)
+        {
+            return;
+        }
+
+        try
+        {
+            await Task.Delay(s_startupDelay, _time, stoppingToken);
+            using var timer = new PeriodicTimer(s_interval, _time);
+            do
+            {
+                try
+                {
+                    await RunOnceAsync(stoppingToken);
+                }
+                catch (Exception ex) when (ex is not OperationCanceledException)
+                {
+                    Failed(ex);
+                }
+            }
+            while (await timer.WaitForNextTickAsync(stoppingToken));
+        }
+        catch (OperationCanceledException)
+        {
+            // 后端正在停止
+        }
+    }
+
+    /// <summary>检查一次；确认了更新（Backend 即将有序退出）返回 true。</summary>
+    public async ValueTask<bool> RunOnceAsync(CancellationToken ct)
+    {
+        if (!_options.AutoUpdate || !_updates.Enabled)
+        {
+            return false;
+        }
+
+        BackendUpdateView view = await _updates.GetAsync(ct);
+        if (view.State != "available" || view.Available is not { } offer)
+        {
+            return false;
+        }
+
+        // 清单的 seq 是发布时间（秒）
+        TimeSpan age = _time.GetUtcNow() - DateTimeOffset.FromUnixTimeSeconds(offer.Seq);
+        if (age < TimeSpan.FromMinutes(Math.Max(0, _options.AutoUpdateDelayMinutes)))
+        {
+            return false;
+        }
+
+        Fleet.Core.Result<bool> result = await _updates.ConfirmAsync(offer.Seq, ct);
+        if (!result.IsSuccess)
+        {
+            Refused(offer.Tag, result.Error.Message);
+            return false;
+        }
+
+        AutoConfirmed(offer.Tag, (int)age.TotalMinutes);
+        return true;
+    }
+
+    [LoggerMessage(Level = LogLevel.Information, Message = "auto update: {Tag} was offered {Minutes} minutes ago, confirming it")]
+    private partial void AutoConfirmed(string tag, int minutes);
+
+    [LoggerMessage(Level = LogLevel.Warning, Message = "auto update to {Tag} was not started: {Reason}")]
+    private partial void Refused(string tag, string reason);
+
+    [LoggerMessage(Level = LogLevel.Warning, Message = "the auto update check failed")]
+    private partial void Failed(Exception exception);
+}
diff --git a/backend/tests/MoShiro.Backend.Tests/BackendUpdateTests.cs b/backend/tests/MoShiro.Backend.Tests/BackendUpdateTests.cs
index fdf0d42..25c02ea 100644
--- a/backend/tests/MoShiro.Backend.Tests/BackendUpdateTests.cs
+++ b/backend/tests/MoShiro.Backend.Tests/BackendUpdateTests.cs
@@ -69,6 +69,33 @@ public sealed class BackendUpdateTests : IAsyncLifetime
         Assert.Equal(HttpStatusCode.Conflict, replay.StatusCode);
     }
 
+    /// <summary>自动更新默认关；打开之后只在新版本登记满设定的时间才确认，走的是和手动一样的路径（先备份）。</summary>
+    [Fact]
+    public async Task AutoUpdate_IsOffByDefault_AndConfirmsOnlyAfterTheOfferHasAged()
+    {
+        BackendOptions options = _backend.Services.GetRequiredService<BackendOptions>();
+        var updater = _backend.Services.GetRequiredService<BackendAutoUpdater>();
+        using HttpResponseMessage old = await PublishAsync(10); // seq 是发布时间（秒）：1970 年，早就过了等待时间
+        Assert.Equal(HttpStatusCode.Created, old.StatusCode);
+
+        Assert.False(await updater.RunOnceAsync(default)); // 默认关
+        Assert.Equal(0, _backend.Restarts.Count);
+
+        options.AutoUpdate = true;
+        options.AutoUpdateDelayMinutes = 10;
+        using HttpResponseMessage fresh = await PublishAsync(TimeProvider.System.GetUtcNow().ToUnixTimeSeconds());
+        Assert.Equal(HttpStatusCode.Created, fresh.StatusCode);
+        Assert.False(await updater.RunOnceAsync(default)); // 刚登记的版本还要等
+        Assert.Equal(0, _backend.Restarts.Count);
+
+        options.AutoUpdateDelayMinutes = 0;
+        Assert.True(await updater.RunOnceAsync(default));
+        Assert.Equal(1, _backend.Restarts.Count);
+        Assert.Single(Directory.GetFiles(Path.Combine(_backend.DataDirectory, "backups"), "pre-update-*.db")); // 先备份
+        Assert.False(await updater.RunOnceAsync(default)); // 已经在更新，不会再确认第二次
+        Assert.Equal(1, _backend.Restarts.Count);
+    }
+
     [Fact]
     public async Task Confirm_BacksUpTheDatabase_ThenExits_AndRejectsASupersededSequence()
     {