diff --git a/src/ClaudeDo.Installer/Steps/StopWorkerStep.cs b/src/ClaudeDo.Installer/Steps/StopWorkerStep.cs
index 753249a..e004153 100644
--- a/src/ClaudeDo.Installer/Steps/StopWorkerStep.cs
+++ b/src/ClaudeDo.Installer/Steps/StopWorkerStep.cs
@@ -7,25 +7,32 @@ namespace ClaudeDo.Installer.Steps;
 public sealed class StopWorkerStep : IInstallStep
 {
     public const string LegacyTaskName = "ClaudeDoWorker";
-    public const string ProcessName = "ClaudeDo.Worker";
+
+    // Both must be stopped before the install dir is touched: a running app/worker
+    // exe locks its directory, so Directory.Move during extraction would otherwise
+    // fail with "Access to the path '...\app' is denied".
+    private static readonly string[] ProcessNames = { "ClaudeDo.Worker", "ClaudeDo.App" };
 
     public string Name => "Stop Worker";
 
     public async Task<StepResult> ExecuteAsync(InstallContext ctx, IProgress<string> progress, CancellationToken ct)
     {
-        progress.Report("Stopping worker process (if running)...");
+        progress.Report("Stopping ClaudeDo processes (if running)...");
         var installDir = ctx.InstallDirectory;
-        foreach (var p in Process.GetProcessesByName(ProcessName))
+        foreach (var name in ProcessNames)
         {
-            try
+            foreach (var p in Process.GetProcessesByName(name))
             {
-                var path = p.MainModule?.FileName;
-                if (path is not null && !IsUnder(path, installDir)) continue;
-                p.Kill(entireProcessTree: true);
-                p.WaitForExit(10000);
+                try
+                {
+                    var path = p.MainModule?.FileName;
+                    if (path is not null && !IsUnder(path, installDir)) continue;
+                    p.Kill(entireProcessTree: true);
+                    p.WaitForExit(10000);
+                }
+                catch { /* process may have exited or be inaccessible */ }
+                finally { p.Dispose(); }
             }
-            catch { /* process may have exited or be inaccessible */ }
-            finally { p.Dispose(); }
         }
         await Task.CompletedTask;
         return StepResult.Ok();