diff --git a/src/ClaudeDo.Ui/ClaudeDo.Ui.csproj b/src/ClaudeDo.Ui/ClaudeDo.Ui.csproj
index c296826..9fddf53 100644
--- a/src/ClaudeDo.Ui/ClaudeDo.Ui.csproj
+++ b/src/ClaudeDo.Ui/ClaudeDo.Ui.csproj
@@ -10,6 +10,7 @@
     <PackageReference Include="CommunityToolkit.Mvvm" Version="8.4.1" />
     <PackageReference Include="Microsoft.AspNetCore.SignalR.Client" Version="8.0.11" />
     <PackageReference Include="Microsoft.Extensions.DependencyInjection" Version="8.0.1" />
+    <PackageReference Include="Microsoft.Win32.Registry" Version="5.0.0" />
   </ItemGroup>
 
   <PropertyGroup>
diff --git a/src/ClaudeDo.Ui/Services/InstallerLocator.cs b/src/ClaudeDo.Ui/Services/InstallerLocator.cs
new file mode 100644
index 0000000..de15542
--- /dev/null
+++ b/src/ClaudeDo.Ui/Services/InstallerLocator.cs
@@ -0,0 +1,47 @@
+namespace ClaudeDo.Ui.Services;
+
+public sealed class InstallerLocator
+{
+    private const string InstallJson = "install.json";
+    private const string InstallerExe = "ClaudeDo.Installer.exe";
+    private const string UninstallerSubdir = "uninstaller";
+
+    public string? Find()
+        => FindByWalkingUp(AppContext.BaseDirectory) ?? FindByRegistry();
+
+    public string? FindByWalkingUp(string startDir)
+    {
+        var dir = new DirectoryInfo(startDir);
+        while (dir is not null)
+        {
+            var manifest = Path.Combine(dir.FullName, InstallJson);
+            if (File.Exists(manifest))
+            {
+                var candidate = Path.Combine(dir.FullName, UninstallerSubdir, InstallerExe);
+                return File.Exists(candidate) ? candidate : null;
+            }
+            dir = dir.Parent;
+        }
+        return null;
+    }
+
+    [System.Runtime.Versioning.SupportedOSPlatform("windows")]
+    public string? FindByRegistry()
+    {
+        if (!OperatingSystem.IsWindows()) return null;
+
+        try
+        {
+            using var key = Microsoft.Win32.Registry.LocalMachine
+                .OpenSubKey(@"Software\Microsoft\Windows\CurrentVersion\Uninstall\ClaudeDo");
+            var location = key?.GetValue("InstallLocation") as string;
+            if (string.IsNullOrEmpty(location)) return null;
+            var candidate = Path.Combine(location, UninstallerSubdir, InstallerExe);
+            return File.Exists(candidate) ? candidate : null;
+        }
+        catch
+        {
+            return null;
+        }
+    }
+}
diff --git a/tests/ClaudeDo.Ui.Tests/Services/InstallerLocatorTests.cs b/tests/ClaudeDo.Ui.Tests/Services/InstallerLocatorTests.cs
new file mode 100644
index 0000000..4ddc948
--- /dev/null
+++ b/tests/ClaudeDo.Ui.Tests/Services/InstallerLocatorTests.cs
@@ -0,0 +1,58 @@
+using ClaudeDo.Ui.Services;
+
+namespace ClaudeDo.Ui.Tests.Services;
+
+public class InstallerLocatorTests : IDisposable
+{
+    private readonly string _root;
+
+    public InstallerLocatorTests()
+    {
+        _root = Path.Combine(Path.GetTempPath(), "ClaudeDo.Ui.Tests-" + Guid.NewGuid().ToString("N"));
+        Directory.CreateDirectory(_root);
+    }
+
+    public void Dispose() { try { Directory.Delete(_root, true); } catch { } }
+
+    [Fact]
+    public void Find_WalkUpFromAppDir_ToInstallJsonSibling()
+    {
+        var installDir = Path.Combine(_root, "ClaudeDo");
+        var appDir = Path.Combine(installDir, "app");
+        var uninstallerDir = Path.Combine(installDir, "uninstaller");
+        Directory.CreateDirectory(appDir);
+        Directory.CreateDirectory(uninstallerDir);
+
+        File.WriteAllText(Path.Combine(installDir, "install.json"), "{}");
+        var installerPath = Path.Combine(uninstallerDir, "ClaudeDo.Installer.exe");
+        File.WriteAllText(installerPath, "x");
+
+        var locator = new InstallerLocator();
+        var found = locator.FindByWalkingUp(appDir);
+
+        Assert.Equal(installerPath, found);
+    }
+
+    [Fact]
+    public void Find_ReturnsNullWhenNoInstallJson()
+    {
+        var appDir = Path.Combine(_root, "somewhere", "app");
+        Directory.CreateDirectory(appDir);
+
+        var locator = new InstallerLocator();
+        Assert.Null(locator.FindByWalkingUp(appDir));
+    }
+
+    [Fact]
+    public void Find_ReturnsNullWhenInstallerMissingFromUninstallerDir()
+    {
+        var installDir = Path.Combine(_root, "ClaudeDo");
+        var appDir = Path.Combine(installDir, "app");
+        Directory.CreateDirectory(appDir);
+        Directory.CreateDirectory(Path.Combine(installDir, "uninstaller"));
+        File.WriteAllText(Path.Combine(installDir, "install.json"), "{}");
+
+        var locator = new InstallerLocator();
+        Assert.Null(locator.FindByWalkingUp(appDir));
+    }
+}