diff --git a/src/ClaudeDo.Installer/CLAUDE.md b/src/ClaudeDo.Installer/CLAUDE.md
index 9a02c039..3e0d96e6 100644
--- a/src/ClaudeDo.Installer/CLAUDE.md
+++ b/src/ClaudeDo.Installer/CLAUDE.md
@@ -75,7 +75,7 @@ claude mcp add --transport http --scope user claudedo http://127.0.0.1:{External
 ```
 Non-fatal if `claude` CLI is missing or too old (prints the manual command). Server name: `claudedo`.
 
-**`RegisterAutostartStep`** — creates a per-user Startup-folder shortcut `ClaudeDo Worker.lnk` (`Environment.SpecialFolder.Startup`). Also migrates away from legacy mechanisms:
+**`RegisterAutostartStep`** — creates a per-user Startup-folder shortcut `ClaudeDo Worker.lnk` (`Environment.SpecialFolder.Startup`); `AutostartShortcut.Install` skips the rewrite (and reports it) when the shortcut already points at the current worker exe, so update/repair runs don't touch it needlessly. Also migrates away from legacy mechanisms, unconditionally on every run (no cached "already migrated" flag — see the comment in the step):
 - Deletes legacy Windows service: `sc.exe stop/delete ClaudeDoWorker`
 - Deletes legacy scheduled task: `schtasks /Delete /TN ClaudeDoWorker`
 
diff --git a/src/ClaudeDo.Installer/Core/AutostartShortcut.cs b/src/ClaudeDo.Installer/Core/AutostartShortcut.cs
index f417b16e..2833df2d 100644
--- a/src/ClaudeDo.Installer/Core/AutostartShortcut.cs
+++ b/src/ClaudeDo.Installer/Core/AutostartShortcut.cs
@@ -11,13 +11,26 @@ public static class AutostartShortcut
 
     public static string PathIn(string startupDir) => Path.Combine(startupDir, FileName);
 
-    public static void Install(string startupDir, string workerExe)
+    /// <summary>Creates or updates the Startup shortcut. Returns false if it already pointed at <paramref name="workerExe"/> and was left untouched.</summary>
+    public static bool Install(string startupDir, string workerExe)
     {
         Directory.CreateDirectory(startupDir);
+        var shortcutPath = PathIn(startupDir);
+        if (File.Exists(shortcutPath))
+        {
+            var existingTarget = ShortcutFactory.TryGetTarget(shortcutPath);
+            if (existingTarget is not null && PathsEqual(existingTarget, workerExe))
+                return false;
+        }
+
         var workingDir = Path.GetDirectoryName(workerExe) ?? startupDir;
-        ShortcutFactory.CreateShortcut(PathIn(startupDir), workerExe, workingDir, "ClaudeDo background worker");
+        ShortcutFactory.CreateShortcut(shortcutPath, workerExe, workingDir, "ClaudeDo background worker");
+        return true;
     }
 
+    private static bool PathsEqual(string a, string b) =>
+        string.Equals(Path.GetFullPath(a), Path.GetFullPath(b), StringComparison.OrdinalIgnoreCase);
+
     public static void Remove(string startupDir)
     {
         var path = PathIn(startupDir);
diff --git a/src/ClaudeDo.Installer/Core/ShortcutFactory.cs b/src/ClaudeDo.Installer/Core/ShortcutFactory.cs
index dedfde39..5d53eb06 100644
--- a/src/ClaudeDo.Installer/Core/ShortcutFactory.cs
+++ b/src/ClaudeDo.Installer/Core/ShortcutFactory.cs
@@ -6,6 +6,8 @@ namespace ClaudeDo.Installer.Core;
 
 public static class ShortcutFactory
 {
+    private const int SlgpRawPath = 0x4;
+
     public static void CreateShortcut(string shortcutPath, string targetPath, string workingDir, string description)
     {
         var link = (IShellLink)new ShellLink();
@@ -18,6 +20,24 @@ public static class ShortcutFactory
         file.Save(shortcutPath, false);
     }
 
+    /// <summary>Reads the target path of an existing .lnk, or null if it can't be read (missing/corrupt).</summary>
+    public static string? TryGetTarget(string shortcutPath)
+    {
+        try
+        {
+            var link = (IShellLink)new ShellLink();
+            ((IPersistFile)link).Load(shortcutPath, 0);
+            var sb = new StringBuilder(260);
+            link.GetPath(sb, sb.Capacity, IntPtr.Zero, SlgpRawPath);
+            var path = sb.ToString();
+            return path.Length == 0 ? null : path;
+        }
+        catch (Exception)
+        {
+            return null;
+        }
+    }
+
     [ComImport]
     [Guid("00021401-0000-0000-C000-000000000046")]
     private class ShellLink { }
diff --git a/src/ClaudeDo.Installer/Steps/RegisterAutostartStep.cs b/src/ClaudeDo.Installer/Steps/RegisterAutostartStep.cs
index 359d9412..fe64bef5 100644
--- a/src/ClaudeDo.Installer/Steps/RegisterAutostartStep.cs
+++ b/src/ClaudeDo.Installer/Steps/RegisterAutostartStep.cs
@@ -16,6 +16,11 @@ public sealed class RegisterAutostartStep : IInstallStep
         if (!File.Exists(workerExe))
             return StepResult.Fail($"Worker executable not found: {workerExe}");
 
+        // Legacy service/task cleanup below runs unconditionally on every install/update/repair,
+        // even though it's a no-op once migrated. A cached "already migrated" flag could go stale
+        // (e.g. a user re-adds the legacy service) and strand them with it still running; two
+        // extra process starts per run is the price for that migration safety net.
+
         // 1) Migrate away the legacy Windows service if present.
         progress.Report("Checking for legacy worker service...");
         var (queryExit, _) = await ProcessRunner.RunAsync("sc.exe", $"query {LegacyServiceName}", null, progress, ct);
@@ -38,10 +43,11 @@ public sealed class RegisterAutostartStep : IInstallStep
         await ProcessRunner.RunAsync("schtasks.exe", $"/Delete /TN \"{LegacyTaskName}\" /F", null, progress, ct);
 
         // 3) Register per-user autostart via a Startup-folder shortcut.
-        progress.Report("Creating Startup shortcut...");
+        progress.Report("Checking Startup shortcut...");
         try
         {
-            AutostartShortcut.Install(AutostartShortcut.DefaultStartupDir, workerExe);
+            var created = AutostartShortcut.Install(AutostartShortcut.DefaultStartupDir, workerExe);
+            progress.Report(created ? "Startup shortcut created." : "Startup shortcut already up to date.");
         }
         catch (Exception ex)
         {
diff --git a/tests/ClaudeDo.Installer.Tests/AutostartShortcutTests.cs b/tests/ClaudeDo.Installer.Tests/AutostartShortcutTests.cs
index bde032a7..4e6dfa43 100644
--- a/tests/ClaudeDo.Installer.Tests/AutostartShortcutTests.cs
+++ b/tests/ClaudeDo.Installer.Tests/AutostartShortcutTests.cs
@@ -22,13 +22,58 @@ public class AutostartShortcutTests
             var workerExe = Path.Combine(workerDir, "ClaudeDo.Worker.exe");
             File.WriteAllText(workerExe, "");
 
-            AutostartShortcut.Install(startup, workerExe);
+            var created = AutostartShortcut.Install(startup, workerExe);
 
+            Assert.True(created);
             Assert.True(File.Exists(Path.Combine(startup, AutostartShortcut.FileName)));
         }
         finally { Directory.Delete(startup, true); Directory.Delete(workerDir, true); }
     }
 
+    [Fact]
+    public void Install_is_noop_when_shortcut_already_targets_same_exe()
+    {
+        var startup = TempDir();
+        var workerDir = TempDir();
+        try
+        {
+            var workerExe = Path.Combine(workerDir, "ClaudeDo.Worker.exe");
+            File.WriteAllText(workerExe, "");
+            AutostartShortcut.Install(startup, workerExe);
+            var writtenAt = File.GetLastWriteTimeUtc(Path.Combine(startup, AutostartShortcut.FileName));
+
+            var createdAgain = AutostartShortcut.Install(startup, workerExe);
+
+            Assert.False(createdAgain);
+            Assert.Equal(writtenAt, File.GetLastWriteTimeUtc(Path.Combine(startup, AutostartShortcut.FileName)));
+        }
+        finally { Directory.Delete(startup, true); Directory.Delete(workerDir, true); }
+    }
+
+    [Fact]
+    public void Install_rewrites_shortcut_when_target_changed()
+    {
+        var startup = TempDir();
+        var workerDir = TempDir();
+        try
+        {
+            var oldExe = Path.Combine(workerDir, "old", "ClaudeDo.Worker.exe");
+            Directory.CreateDirectory(Path.GetDirectoryName(oldExe)!);
+            File.WriteAllText(oldExe, "");
+            AutostartShortcut.Install(startup, oldExe);
+
+            var newExe = Path.Combine(workerDir, "new", "ClaudeDo.Worker.exe");
+            Directory.CreateDirectory(Path.GetDirectoryName(newExe)!);
+            File.WriteAllText(newExe, "");
+
+            var created = AutostartShortcut.Install(startup, newExe);
+
+            Assert.True(created);
+            Assert.Equal(newExe, ShortcutFactory.TryGetTarget(Path.Combine(startup, AutostartShortcut.FileName)));
+        }
+        finally { Directory.Delete(startup, true); Directory.Delete(workerDir, true); }
+    }
+
     [Fact]
     public void Remove_deletes_existing_lnk()
     {