diff --git a/MediaBrowser.Controller/ScheduledTasks/ScanLeaderOptions.cs b/MediaBrowser.Controller/ScheduledTasks/ScanLeaderOptions.cs
index 9818898181..d7533b7d20 100644
--- a/MediaBrowser.Controller/ScheduledTasks/ScanLeaderOptions.cs
+++ b/MediaBrowser.Controller/ScheduledTasks/ScanLeaderOptions.cs
@@ -43,6 +43,14 @@ public sealed class ScanLeaderOptions
         "TaskExtractMediaSegments",
         "KeyframeExtraction",
         "CleanupUserDataTask",
-        "OptimizeDatabaseTask"
+        "OptimizeDatabaseTask",
+        "DownloadLyrics",
+        "DownloadSubtitles",
+        "TmdbRefreshUpcomingEpisodes",
+        "RefreshTrickplayImages",
+        "MoveTrickplayImages",
+        "RefreshInternetChannels",
+        "RefreshGuide",
+        "PluginUpdates"
     };
 }
diff --git a/tests/Jellyfin.Server.Implementations.Tests/Jellyfin.Server.Implementations.Tests.csproj b/tests/Jellyfin.Server.Implementations.Tests/Jellyfin.Server.Implementations.Tests.csproj
index f8d35c39af..dc06861cba 100644
--- a/tests/Jellyfin.Server.Implementations.Tests/Jellyfin.Server.Implementations.Tests.csproj
+++ b/tests/Jellyfin.Server.Implementations.Tests/Jellyfin.Server.Implementations.Tests.csproj
@@ -31,6 +31,8 @@
   <ItemGroup>
     <ProjectReference Include="..\..\Emby.Server.Implementations\Emby.Server.Implementations.csproj" />
     <ProjectReference Include="..\..\Jellyfin.Server.Implementations\Jellyfin.Server.Implementations.csproj" />
+    <ProjectReference Include="..\..\MediaBrowser.Providers\MediaBrowser.Providers.csproj" />
+    <ProjectReference Include="..\..\src\Jellyfin.LiveTv\Jellyfin.LiveTv.csproj" />
     <ProjectReference Include="..\Jellyfin.Server.Integration.Tests\Jellyfin.Server.Integration.Tests.csproj" />
     <ProjectReference Include="..\..\src\Jellyfin.Database\Jellyfin.Database.Implementations\Jellyfin.Database.Implementations.csproj" />
   </ItemGroup>
diff --git a/tests/Jellyfin.Server.Implementations.Tests/ScheduledTasks/ScanLeaderOptionsTests.cs b/tests/Jellyfin.Server.Implementations.Tests/ScheduledTasks/ScanLeaderOptionsTests.cs
index 6642775a3a..b7a67dfe06 100644
--- a/tests/Jellyfin.Server.Implementations.Tests/ScheduledTasks/ScanLeaderOptionsTests.cs
+++ b/tests/Jellyfin.Server.Implementations.Tests/ScheduledTasks/ScanLeaderOptionsTests.cs
@@ -1,6 +1,8 @@
 using System;
 using System.Collections.Generic;
+using System.IO;
 using System.Linq;
+using System.Reflection;
 using System.Runtime.CompilerServices;
 using Emby.Server.Implementations.ScheduledTasks.Tasks;
 using MediaBrowser.Controller.ScheduledTasks;
@@ -11,6 +13,14 @@ namespace Jellyfin.Server.Implementations.Tests.ScheduledTasks;
 
 public class ScanLeaderOptionsTests
 {
+    private static readonly Assembly[] _taskAssemblies =
+    {
+        typeof(DeleteTranscodeFileTask).Assembly,
+        typeof(MediaBrowser.Providers.Lyric.LyricScheduledTask).Assembly,
+        typeof(Jellyfin.LiveTv.Guide.RefreshGuideScheduledTask).Assembly,
+        typeof(Jellyfin.MediaEncoding.Hls.ScheduledTasks.KeyframeExtractionScheduledTask).Assembly
+    };
+
     /// <summary>
     /// A gated key that matches no registered task silently stops gating anything, so the default
     /// set is pinned to the task keys that actually exist in the build.
@@ -18,28 +28,92 @@ public class ScanLeaderOptionsTests
     [Fact]
     public void DefaultGatedTaskKeys_Should_MatchRegisteredScheduledTasks()
     {
-        var registeredKeys = DiscoverScheduledTaskKeys();
+        var registeredKeys = DiscoverScheduledTaskKeys(_taskAssemblies);
 
         Assert.NotEmpty(registeredKeys);
-        Assert.Empty(new ScanLeaderOptions().GatedTaskKeys.Except(registeredKeys, StringComparer.Ordinal));
+
+        var unmatched = new ScanLeaderOptions().GatedTaskKeys.Except(registeredKeys, StringComparer.Ordinal).ToList();
+        Assert.True(
+            unmatched.Count == 0,
+            $"Gated keys match no scheduled task: {string.Join(", ", unmatched)}. Known keys: {string.Join(", ", registeredKeys.Order(StringComparer.Ordinal))}");
     }
 
-    private static HashSet<string> DiscoverScheduledTaskKeys()
+    /// <summary>
+    /// A key dropped from the default set silently un-gates that task on every replica, so the whole
+    /// set is pinned against a hand-maintained expectation rather than read back from the options.
+    /// </summary>
+    [Fact]
+    public void DefaultGatedTaskKeys_Should_BeTheExpectedSet()
     {
-        var keys = new HashSet<string>(StringComparer.Ordinal);
-        var assemblies = new[]
+        string[] expected =
         {
-            typeof(DeleteTranscodeFileTask).Assembly,
-            typeof(Jellyfin.MediaEncoding.Hls.ScheduledTasks.KeyframeExtractionScheduledTask).Assembly
+            "AudioNormalization",
+            "CleanupUserDataTask",
+            "DownloadLyrics",
+            "DownloadSubtitles",
+            "KeyframeExtraction",
+            "MoveTrickplayImages",
+            "OptimizeDatabaseTask",
+            "PluginUpdates",
+            "RefreshChapterImages",
+            "RefreshGuide",
+            "RefreshInternetChannels",
+            "RefreshLibrary",
+            "RefreshPeople",
+            "RefreshTrickplayImages",
+            "TaskExtractMediaSegments",
+            "TmdbRefreshUpcomingEpisodes"
         };
 
-        foreach (var type in assemblies.SelectMany(a => a.GetTypes()))
+        var actual = new ScanLeaderOptions().GatedTaskKeys;
+        var missing = expected.Except(actual, StringComparer.Ordinal).ToList();
+        var unexpected = actual.Except(expected, StringComparer.Ordinal).ToList();
+
+        Assert.True(
+            missing.Count == 0 && unexpected.Count == 0,
+            $"Default gated task keys drifted. Missing: {Describe(missing)}. Unexpected: {Describe(unexpected)}.");
+    }
+
+    /// <summary>
+    /// The key universe is only as complete as the assemblies it is read from, so a task added to an
+    /// unscanned assembly must fail here rather than narrow what the previous test can catch.
+    /// </summary>
+    [Fact]
+    public void TaskAssemblies_Should_CoverEveryAssemblyDeclaringScheduledTasks()
+    {
+        var scanned = _taskAssemblies.Select(a => a.GetName().Name).ToHashSet(StringComparer.Ordinal);
+        var missing = new List<string>();
+
+        foreach (var path in Directory.EnumerateFiles(AppContext.BaseDirectory, "*.dll"))
         {
-            if (type.IsAbstract || type.IsInterface || !typeof(IScheduledTask).IsAssignableFrom(type))
+            var name = Path.GetFileNameWithoutExtension(path);
+            if (scanned.Contains(name)
+                || name.EndsWith(".Tests", StringComparison.Ordinal)
+                || !(name.StartsWith("Jellyfin.", StringComparison.Ordinal)
+                    || name.StartsWith("Emby.", StringComparison.Ordinal)
+                    || name.StartsWith("MediaBrowser.", StringComparison.Ordinal)))
             {
                 continue;
             }
 
+            if (GetScheduledTaskTypes(Assembly.LoadFrom(path)).Any())
+            {
+                missing.Add(name);
+            }
+        }
+
+        Assert.True(missing.Count == 0, $"Assemblies declaring scheduled tasks but not scanned: {string.Join(", ", missing)}");
+    }
+
+    private static string Describe(IReadOnlyCollection<string> keys)
+        => keys.Count == 0 ? "none" : string.Join(", ", keys.Order(StringComparer.Ordinal));
+
+    private static HashSet<string> DiscoverScheduledTaskKeys(IEnumerable<Assembly> assemblies)
+    {
+        var keys = new HashSet<string>(StringComparer.Ordinal);
+
+        foreach (var type in assemblies.SelectMany(GetScheduledTaskTypes))
+        {
             // Task keys are constant expressions, so an uninitialised instance is enough to read
             // them without standing up each task's dependency graph.
             var task = (IScheduledTask)RuntimeHelpers.GetUninitializedObject(type);
@@ -48,4 +122,21 @@ public class ScanLeaderOptionsTests
 
         return keys;
     }
+
+    private static IEnumerable<Type> GetScheduledTaskTypes(Assembly assembly)
+    {
+        Type?[] types;
+        try
+        {
+            types = assembly.GetTypes();
+        }
+        catch (ReflectionTypeLoadException ex)
+        {
+            types = ex.Types;
+        }
+
+        return types
+            .Where(t => t is not null && !t.IsAbstract && !t.IsInterface && typeof(IScheduledTask).IsAssignableFrom(t))
+            .Select(t => t!);
+    }
 }