diff --git a/src/c#/GeneralUpdate.Core/Bootstrap/GeneralUpdateBootstrap.cs b/src/c#/GeneralUpdate.Core/Bootstrap/GeneralUpdateBootstrap.cs
index a071a6db..0c486a6f 100644
--- a/src/c#/GeneralUpdate.Core/Bootstrap/GeneralUpdateBootstrap.cs
+++ b/src/c#/GeneralUpdate.Core/Bootstrap/GeneralUpdateBootstrap.cs
@@ -53,18 +53,33 @@ namespace GeneralUpdate.Core;
 /// components, network policies, and OS strategy.</para>
 /// </remarks>
 /// <example>
+/// <para><b>Standard flow (Client):</b></para>
 /// <code>
 /// var result = await new GeneralUpdateBootstrap()
-///     .SetConfig(new UpdateRequest {
-///         UpdateUrl = "https://api.example.com",
-///         ClientVersion = "1.0.0",
-///         InstallPath = @"C:\MyApp",
-///         AppSecretKey = "my-key"
-///     })
+///     .SetSource("https://api.example.com", "my-key")
 ///     .SetOption(Option.AppType, AppType.Client)
 ///     .Hooks&lt;MyCustomHooks&gt;()
 ///     .LaunchAsync();
 /// </code>
+/// <para><b>OSS flow (Object Storage Service):</b></para>
+/// <code>
+/// // OssClient — only secrets in code; identity from generalupdate.manifest.json
+/// var result = await new GeneralUpdateBootstrap()
+///     .SetSource("https://oss.example.com/versions.json", "my-key")
+///     .SetOption(Option.AppType, AppType.OssClient)
+///     .Hooks&lt;MyCustomHooks&gt;()
+///     .LaunchAsync();
+///
+/// // OssUpgrade — running from a subdirectory; pass installPath to locate
+/// // generalupdate.manifest.json in the parent directory
+/// var installPath = Path.GetFullPath(Path.Combine(baseDir, ".."));
+/// var result = await new GeneralUpdateBootstrap()
+///     .SetSource("https://oss.example.com/versions.json", "my-key",
+///         installPath: installPath)
+///     .SetOption(Option.AppType, AppType.OssUpgrade)
+///     .Hooks&lt;MyCustomHooks&gt;()
+///     .LaunchAsync();
+/// </code>
 /// </example>
 public class GeneralUpdateBootstrap : AbstractBootstrap<GeneralUpdateBootstrap, IStrategy>
 {
@@ -232,15 +247,29 @@ public GeneralUpdateBootstrap SetConfig(string filePath)
     /// <summary>
     ///     Zero-config entry-point: supply only secrets. Provides sensible identity defaults
     ///     that pass <see cref="UpdateRequest.Validate"/>; the real identity metadata is
-    ///     discovered later by <see cref="ClientStrategy"/> from <c>generalupdate.manifest.json</c>.
+    ///     discovered later by <see cref="ClientStrategy"/> or <see cref="OssStrategy"/>
+    ///     from <c>generalupdate.manifest.json</c>. Works with all <see cref="AppType"/>
+    ///     modes (<c>Client</c>, <c>Upgrade</c>, <c>OssClient</c>, <c>OssUpgrade</c>).
     /// </summary>
+    /// <param name="updateUrl">The remote endpoint for update validation or version config retrieval.</param>
+    /// <param name="appSecretKey">The application secret key used for authentication.</param>
+    /// <param name="reportUrl">Optional URL for reporting update status back to the server.</param>
+    /// <param name="scheme">Optional URL scheme override (e.g. <c>"https"</c>).</param>
+    /// <param name="token">Optional authentication token for API requests.</param>
+    /// <param name="installPath">
+    /// Optional override for the installation root directory. When <c>null</c>,
+    /// defaults to <see cref="AppDomain.CurrentDomain.BaseDirectory"/>. Set this when
+    /// the current process runs from a subdirectory (e.g. the OSS upgrade process in
+    /// <c>update/</c>) and <c>generalupdate.manifest.json</c> lives in the parent.
+    /// </param>
     /// <returns>This bootstrap instance for chaining.</returns>
     public GeneralUpdateBootstrap SetSource(
         string updateUrl,
         string appSecretKey,
         string? reportUrl = null,
         string? scheme = null,
-        string? token = null)
+        string? token = null,
+        string? installPath = null)
     {
         var config = new UpdateRequest
         {
@@ -250,6 +279,8 @@ public GeneralUpdateBootstrap SetSource(
             Scheme = scheme,
             ReportUrl = reportUrl
         };
+        if (installPath != null)
+            config.InstallPath = installPath;
         return SetConfig(config);
     }
 
diff --git a/src/c#/GeneralUpdate.Core/Configuration/UpdateRequest.cs b/src/c#/GeneralUpdate.Core/Configuration/UpdateRequest.cs
index d3a675ac..b3f9ea30 100644
--- a/src/c#/GeneralUpdate.Core/Configuration/UpdateRequest.cs
+++ b/src/c#/GeneralUpdate.Core/Configuration/UpdateRequest.cs
@@ -62,17 +62,8 @@ public void Validate()
             if (!string.IsNullOrWhiteSpace(UpdateLogUrl) && !Uri.IsWellFormedUriString(UpdateLogUrl, UriKind.Absolute))
                 throw new ArgumentException("Invalid UpdateLogUrl");
 
-            if (string.IsNullOrWhiteSpace(UpdateAppName))
-                throw new ArgumentException("UpdateAppName cannot be empty");
-
-            if (string.IsNullOrWhiteSpace(MainAppName))
-                throw new ArgumentException("MainAppName cannot be empty");
-
             if (string.IsNullOrWhiteSpace(AppSecretKey))
                 throw new ArgumentException("AppSecretKey cannot be empty");
-
-            if (string.IsNullOrWhiteSpace(ClientVersion))
-                throw new ArgumentException("ClientVersion cannot be empty");
         }
     }
 }
diff --git a/src/c#/GeneralUpdate.Core/Strategy/OssStrategy.cs b/src/c#/GeneralUpdate.Core/Strategy/OssStrategy.cs
index 0d6d31db..65270a2b 100644
--- a/src/c#/GeneralUpdate.Core/Strategy/OssStrategy.cs
+++ b/src/c#/GeneralUpdate.Core/Strategy/OssStrategy.cs
@@ -150,7 +150,12 @@ public async Task ExecuteAsync()
         if (_configInfo == null)
             throw new InvalidOperationException("OssStrategy not configured. Call Create() first.");
 
-        // Dispatch by role �?no env-var detection needed.
+        // Fill missing identity fields from generalupdate.manifest.json,
+        // making the manifest the single source of configuration across
+        // all update flows (standard ClientStrategy and OssStrategy).
+        Configuration.AppMetadataDiscoverer.Discover(_configInfo);
+
+        // Dispatch by role — no env-var detection needed.
         if (_role == AppType.OssUpgrade)
         {
             await ExecuteUpgradeAsync();
@@ -189,35 +194,63 @@ private async Task ExecuteClientAsync()
         var versionFileName = $"{_configInfo.MainAppName ?? _configInfo.UpdateAppName}_versions.json";
         var versionsFilePath = Path.Combine(installPath, versionFileName);
 
+        GeneralTracer.Info($"[OssClient] InstallPath={installPath}");
+        GeneralTracer.Info($"[OssClient] VersionFileName={versionFileName}");
+        GeneralTracer.Info($"[OssClient] ClientVersion={_configInfo.ClientVersion}");
+        GeneralTracer.Info($"[OssClient] MainAppName={_configInfo.MainAppName}");
+        GeneralTracer.Info($"[OssClient] UpdateAppName={_configInfo.UpdateAppName}");
+
         if (!string.IsNullOrEmpty(_configInfo.UpdateUrl))
         {
+            GeneralTracer.Info($"[OssClient] Downloading from {_configInfo.UpdateUrl} ...");
             await DownloadVersionConfig(_configInfo.UpdateUrl, versionsFilePath).ConfigureAwait(false);
+            GeneralTracer.Info($"[OssClient] Downloaded -> {versionsFilePath}");
         }
 
         if (!File.Exists(versionsFilePath))
         {
-            GeneralTracer.Info("OssStrategy: version config download failed, aborting.");
+            GeneralTracer.Info("[OssClient] FAIL: version config file not found after download!");
             return;
         }
 
-        var versions = JsonSerializer.Deserialize(
-            File.ReadAllText(versionsFilePath),
-            JsonContext.OssVersionRecordJsonContext.Default.ListOssVersionRecord);
+        var jsonText = File.ReadAllText(versionsFilePath);
+        GeneralTracer.Info($"[OssClient] JSON downloaded ({jsonText.Length} chars)");
+
+        List<OssVersionRecord> versions;
+        try
+        {
+            versions = JsonSerializer.Deserialize(
+                jsonText,
+                JsonContext.OssVersionRecordJsonContext.Default.ListOssVersionRecord);
+        }
+        catch (Exception ex)
+        {
+            GeneralTracer.Error($"[OssClient] JSON deserialize error: {ex.GetType().Name}: {ex.Message}", ex);
+            throw;
+        }
+
         if (versions == null || versions.Count == 0)
         {
-            GeneralTracer.Info("OssStrategy: no versions found, aborting.");
+            GeneralTracer.Info($"[OssClient] FAIL: no versions found (count={versions?.Count.ToString() ?? "null"})");
             return;
         }
 
+        GeneralTracer.Info($"[OssClient] Deserialized {versions.Count} version(s)");
+        foreach (var v in versions)
+            GeneralTracer.Info($"  - {v.PacketName} v{v.Version} PubTime={v.PubTime:O}");
+
         versions = versions.OrderByDescending(x => x.PubTime).ToList();
         var latest = versions.First();
+        GeneralTracer.Info($"[OssClient] Latest: {latest.Version} (PubTime={latest.PubTime:O})");
 
         if (!IsOssUpgrade(_configInfo.ClientVersion, latest.Version))
         {
-            GeneralTracer.Info("OssStrategy: no upgrade needed.");
+            GeneralTracer.Info($"[OssClient] No upgrade needed: {_configInfo.ClientVersion} >= {latest.Version}");
             return;
         }
 
+        GeneralTracer.Info($"[OssClient] Upgrade needed: {_configInfo.ClientVersion} -> {latest.Version}");
+
         // Resolve upgrade exe: prefer UpdatePath, fall back to InstallPath
         var upgradeDir = !string.IsNullOrWhiteSpace(_configInfo.UpdatePath)
             ? (Path.IsPathRooted(_configInfo.UpdatePath)
@@ -228,10 +261,28 @@ private async Task ExecuteClientAsync()
             ? _configInfo.UpdateAppName
             : "GeneralUpdate.Upgrade.exe";
         var appPath = Path.Combine(upgradeDir, upgradeAppName);
+        GeneralTracer.Info($"[OssClient] Resolved upgrade path: {appPath}");
+
+        // List exe files in the directory to help diagnose missing file issues
+        try
+        {
+            var dirFiles = Directory.GetFiles(upgradeDir, "*.exe").Select(f => Path.GetFileName(f));
+            GeneralTracer.Info($"[OssClient] *.exe files in {upgradeDir}: [{string.Join(", ", dirFiles)}]");
+        }
+        catch (Exception ex)
+        {
+            GeneralTracer.Warn($"[OssClient] Could not list directory {upgradeDir}: {ex.Message}");
+        }
+
         if (!File.Exists(appPath))
+        {
+            GeneralTracer.Error($"[OssClient] FAIL: Upgrade app NOT FOUND at {appPath}");
             throw new FileNotFoundException($"Upgrade application not found: {appPath}");
+        }
 
+        GeneralTracer.Info($"[OssClient] Launching upgrade: {appPath}");
         Process.Start(appPath);
+        GeneralTracer.Info("[OssClient] Upgrade launched, exiting.");
         await GracefulExit.CurrentProcessAsync().ConfigureAwait(false);
     }
 
@@ -273,15 +324,6 @@ private async Task ExecuteUpgradeAsync()
             if (!File.Exists(jsonPath) && DownloadSource == null)
                 throw new FileNotFoundException($"Version config not found: {jsonPath}");
 
-            // Hooks: allow cancellation before download
-            if (!await SafeOnBeforeUpdateAsync(ctx).ConfigureAwait(false))
-            {
-                GeneralTracer.Info("OssStrategy (upgrade): cancelled by hook.");
-                return;
-            }
-
-            await SafeReportUpdateStartedAsync(ctx).ConfigureAwait(false);
-
             // Build download assets from version config or injected source
             List<DownloadAsset> assets;
             if (DownloadSource != null)
@@ -314,6 +356,25 @@ private async Task ExecuteUpgradeAsync()
             if (assets.Count == 0)
                 throw new InvalidOperationException("No assets to download.");
 
+            // Compute LastVersion deterministically via Version comparison
+            // so hooks see the correct TargetVersion regardless of source ordering.
+            _configInfo.LastVersion = assets
+                .Select(a => new Version(a.Version))
+                .Max()!
+                .ToString();
+            ctx = BuildUpdateContext();
+
+            // Hooks: allow cancellation before download. Called after assets are
+            // built and LastVersion is set so OnBeforeUpdateAsync sees the real
+            // TargetVersion for decision-making.
+            if (!await SafeOnBeforeUpdateAsync(ctx).ConfigureAwait(false))
+            {
+                GeneralTracer.Info("OssStrategy (upgrade): cancelled by hook.");
+                return;
+            }
+
+            await SafeReportUpdateStartedAsync(ctx).ConfigureAwait(false);
+
             GeneralTracer.Debug($"OssStrategy (upgrade): downloading {assets.Count} asset(s).");
             await DownloadAssetsAsync(assets, installPath).ConfigureAwait(false);
 
@@ -321,6 +382,12 @@ private async Task ExecuteUpgradeAsync()
             var encoding = Encoding.GetEncoding(_configInfo?.Encoding?.CodePage ?? Encoding.UTF8.CodePage);
             DecompressAssets(assets, installPath, encoding);
 
+            // Update generalupdate.manifest.json ClientVersion so the client
+            // reads the correct version on next startup, preventing infinite loops.
+            Configuration.ManifestInfo.TryUpdateVersion(
+                installPath,
+                clientVersion: _configInfo.LastVersion);
+
             await SafeOnDownloadCompletedAsync(ctx).ConfigureAwait(false);
             await SafeOnAfterUpdateAsync(ctx).ConfigureAwait(false);
             await SafeReportUpdateAppliedAsync(ctx).ConfigureAwait(false);
diff --git a/tests/ClientTest/Program.cs b/tests/ClientTest/Program.cs
index a68ec96f..e0e9668c 100644
--- a/tests/ClientTest/Program.cs
+++ b/tests/ClientTest/Program.cs
@@ -6,6 +6,68 @@
 using GeneralUpdate.Core.Hooks;
 
 try
+{
+    await RunOssClientAsync();
+    /*var isOssMode = args.Length > 0 && args[0] == "--oss";
+
+    if (isOssMode)
+    {
+        await RunOssClientAsync();
+    }
+    else
+    {
+        await RunStandardClientAsync();
+    }*/
+}
+catch (Exception ex)
+{
+    Console.WriteLine($"FATAL: {ex}");
+    Console.WriteLine("Press Enter to exit...");
+    Console.ReadLine();
+    Environment.Exit(1);
+}
+
+Console.WriteLine("Press Enter to exit...");
+Console.ReadLine();
+
+// ═══════════════════════════════════════════════════════════════════
+// OSS Client mode — version JSON download → version compare → launch upgrade
+// ═══════════════════════════════════════════════════════════════════
+static async Task RunOssClientAsync()
+{
+    Console.WriteLine("=== GeneralUpdate OSS Client Test ===");
+    Console.WriteLine($"Started at {DateTime.Now}");
+    Console.WriteLine($"Running from: {AppDomain.CurrentDomain.BaseDirectory}");
+
+    // Only secrets are supplied in code. Identity fields (MainAppName,
+    // ClientVersion, UpdateAppName, UpdatePath) are read from
+    // generalupdate.manifest.json by OssStrategy via
+    // AppMetadataDiscoverer.Discover() — same as the standard flow.
+    var updateUrl = "http://localhost:5000/packages/versions.json";
+    var appSecretKey = "dfeb5833-975e-4afb-88f1-6278ee9aeff6";
+
+    Console.WriteLine($"UpdateUrl: {updateUrl}");
+    Console.WriteLine();
+
+    await new GeneralUpdateBootstrap()
+        .SetSource(updateUrl, appSecretKey)
+        .SetOption(Option.AppType, AppType.OssClient)
+        .Hooks<ClientTestHooks>()
+        .AddListenerMultiDownloadStatistics(OnDownloadStatistics)
+        .AddListenerMultiDownloadCompleted(OnDownloadCompleted)
+        .AddListenerMultiAllDownloadCompleted(OnAllDownloadCompleted)
+        .AddListenerMultiDownloadError(OnDownloadError)
+        .AddListenerException(OnException)
+        .AddListenerUpdateInfo(OnUpdateInfo)
+        .LaunchAsync();
+
+    Console.WriteLine("OSS Client test completed.");
+}
+
+// ═══════════════════════════════════════════════════════════════════
+// Standard Client mode — silent poll with IPC handoff to Upgrade
+// ═══════════════════════════════════════════════════════════════════
+static async Task RunStandardClientAsync()
 {
     Console.WriteLine("=== GeneralUpdate Client Test (Silent Mode) ===");
     Console.WriteLine($"Started at {DateTime.Now}");
@@ -47,14 +109,12 @@
     Console.WriteLine();
 
     // Keep the process alive so the background poll loop can work.
-    // When the user presses Ctrl+C or Enter, the process exits and
-    // ProcessExit fires, which triggers the upgrade launch.
     var cts = new CancellationTokenSource();
     Console.CancelKeyPress += (_, e) =>
     {
         Console.WriteLine();
         Console.WriteLine("[Shutdown] Ctrl+C pressed. Exiting...");
-        e.Cancel = true; // Prevent immediate kill — let ProcessExit fire
+        e.Cancel = true;
         cts.Cancel();
     };
 
@@ -67,10 +127,6 @@
         // Expected on Ctrl+C — graceful shutdown
     }
 
-    // Explicitly launch the upgrade process before exiting.
-    // ProcessExit may not fire reliably in all scenarios (e.g. console Ctrl+C),
-    // so we call TryLaunchUpgrade() directly as the primary launch path.
-    // If ProcessExit also fires later, the _updaterStarted guard prevents a double-launch.
     Console.WriteLine("[Shutdown] Launching upgrade process...");
     if (orchestrator != null && orchestrator.HasPreparedUpdate)
     {
@@ -86,11 +142,10 @@
 
     Console.WriteLine("[Shutdown] Client test exiting gracefully.");
 }
-catch (Exception ex)
-{
-    Console.WriteLine($"FATAL: {ex}");
-    Environment.Exit(1);
-}
+
+// ═══════════════════════════════════════════════════════════════════
+// Event handlers (shared across both modes)
+// ═══════════════════════════════════════════════════════════════════
 
 static void OnDownloadStatistics(object sender, MultiDownloadStatisticsEventArgs e)
 {
@@ -136,6 +191,10 @@ static void OnUpdateInfo(object sender, UpdateInfoEventArgs e)
     }
 }
 
+// ═══════════════════════════════════════════════════════════════════
+// Hooks (shared across both modes)
+// ═══════════════════════════════════════════════════════════════════
+
 sealed class ClientTestHooks : IUpdateHooks
 {
     public async Task<bool> OnBeforeUpdateAsync(HookContext ctx)
diff --git a/tests/CoreTest/Bootstrap/ParameterMatrixAndEventTests.cs b/tests/CoreTest/Bootstrap/ParameterMatrixAndEventTests.cs
index cad3684a..2626e4c5 100644
--- a/tests/CoreTest/Bootstrap/ParameterMatrixAndEventTests.cs
+++ b/tests/CoreTest/Bootstrap/ParameterMatrixAndEventTests.cs
@@ -190,8 +190,9 @@ public void Configinfo_Validate_MissingUpdateUrl_Throws()
         }
 
         [Fact]
-        public void Configinfo_Validate_MissingMainAppName_Throws()
+        public void Configinfo_Validate_MissingMainAppName_DoesNotThrow()
         {
+            // MainAppName is optional — filled from manifest by strategies.
             var config = new UpdateRequest
             {
                 UpdateUrl = "https://api.example.com",
@@ -200,12 +201,14 @@ public void Configinfo_Validate_MissingMainAppName_Throws()
                 MainAppName = null!
             };
 
-            Assert.Throws<ArgumentException>(() => config.Validate());
+            var ex = Record.Exception(() => config.Validate());
+            Assert.Null(ex);
         }
 
         [Fact]
-        public void Configinfo_Validate_MissingClientVersion_Throws()
+        public void Configinfo_Validate_MissingClientVersion_DoesNotThrow()
         {
+            // ClientVersion is optional — filled from manifest by strategies.
             var config = new UpdateRequest
             {
                 UpdateUrl = "https://api.example.com",
@@ -214,7 +217,8 @@ public void Configinfo_Validate_MissingClientVersion_Throws()
                 ClientVersion = null!
             };
 
-            Assert.Throws<ArgumentException>(() => config.Validate());
+            var ex = Record.Exception(() => config.Validate());
+            Assert.Null(ex);
         }
 
         [Theory]
diff --git a/tests/CoreTest/Configuration/UpdateRequestTests.cs b/tests/CoreTest/Configuration/UpdateRequestTests.cs
index bc0c14c2..c11a784c 100644
--- a/tests/CoreTest/Configuration/UpdateRequestTests.cs
+++ b/tests/CoreTest/Configuration/UpdateRequestTests.cs
@@ -95,8 +95,9 @@ public void Validate_UpdateLogUrlInvalid_ThrowsArgumentException()
     [InlineData(null)]
     [InlineData("")]
     [InlineData("   ")]
-    public void Validate_UpgradeAppNameNullOrWhitespace_ThrowsArgumentException(string appName)
+    public void Validate_UpgradeAppNameNullOrWhitespace_NoException(string appName)
     {
+        // UpdateAppName is optional — filled from manifest by strategies.
         var config = new UpdateRequest
         {
             UpdateUrl = "https://api.example.com",
@@ -106,15 +107,17 @@ public void Validate_UpgradeAppNameNullOrWhitespace_ThrowsArgumentException(stri
             ClientVersion = "1.0.0",
             InstallPath = "C:\\app"
         };
-        Assert.Throws<ArgumentException>(() => config.Validate());
+        var ex = Record.Exception(() => config.Validate());
+        Assert.Null(ex);
     }
 
     [Theory]
     [InlineData(null)]
     [InlineData("")]
     [InlineData("   ")]
-    public void Validate_MainAppNameNullOrWhitespace_ThrowsArgumentException(string mainUpgradeAppName)
+    public void Validate_MainAppNameNullOrWhitespace_NoException(string mainUpgradeAppName)
     {
+        // MainAppName is optional — filled from manifest by strategies.
         var config = new UpdateRequest
         {
             UpdateUrl = "https://api.example.com",
@@ -124,7 +127,8 @@ public void Validate_MainAppNameNullOrWhitespace_ThrowsArgumentException(string
             ClientVersion = "1.0.0",
             InstallPath = "C:\\app"
         };
-        Assert.Throws<ArgumentException>(() => config.Validate());
+        var ex = Record.Exception(() => config.Validate());
+        Assert.Null(ex);
     }
 
     [Theory]
@@ -149,8 +153,9 @@ public void Validate_AppSecretKeyNullOrWhitespace_ThrowsArgumentException(string
     [InlineData(null)]
     [InlineData("")]
     [InlineData("   ")]
-    public void Validate_ClientVersionNullOrWhitespace_ThrowsArgumentException(string clientVersion)
+    public void Validate_ClientVersionNullOrWhitespace_NoException(string clientVersion)
     {
+        // ClientVersion is optional — filled from manifest by strategies.
         var config = new UpdateRequest
         {
             UpdateUrl = "https://api.example.com",
@@ -160,7 +165,8 @@ public void Validate_ClientVersionNullOrWhitespace_ThrowsArgumentException(strin
             ClientVersion = clientVersion,
             InstallPath = "C:\\app"
         };
-        Assert.Throws<ArgumentException>(() => config.Validate());
+        var ex = Record.Exception(() => config.Validate());
+        Assert.Null(ex);
     }
 
     [Theory]
diff --git a/tests/UpgradeTest/Program.cs b/tests/UpgradeTest/Program.cs
index 2f510234..ef728de2 100644
--- a/tests/UpgradeTest/Program.cs
+++ b/tests/UpgradeTest/Program.cs
@@ -5,6 +5,70 @@
 using GeneralUpdate.Core.Hooks;
 
 try
+{
+    await RunOssUpgradeAsync();
+    /*var isOssMode = args.Length > 0 && args[0] == "--oss";
+
+    if (isOssMode)
+    {
+        await RunOssUpgradeAsync();
+    }
+    else
+    {
+        await RunStandardUpgradeAsync();
+    }*/
+}
+catch (Exception ex)
+{
+    Console.WriteLine($"FATAL: {ex}");
+    Environment.Exit(1);
+}
+
+// ═══════════════════════════════════════════════════════════════════
+// OSS Upgrade mode — read versions.json → download packages → decompress → launch main app
+// ═══════════════════════════════════════════════════════════════════
+static async Task RunOssUpgradeAsync()
+{
+    Console.WriteLine("=== GeneralUpdate OSS Upgrade Test ===");
+    Console.WriteLine($"Started at {DateTime.Now}");
+    Console.WriteLine($"Running from: {AppDomain.CurrentDomain.BaseDirectory}");
+
+    // OssUpgrade runs from a subdirectory (e.g. update/), but the manifest
+    // and versions.json are in the parent directory (same as OssClient).
+    // InstallPath resolves to the parent so OssStrategy reads the correct
+    // manifest and versions.json.
+    var baseDir = AppDomain.CurrentDomain.BaseDirectory;
+    var installPath = Path.GetFullPath(Path.Combine(baseDir, ".."));
+
+    Console.WriteLine($"BaseDir={baseDir}");
+    Console.WriteLine($"InstallPath={installPath} (parent, where manifest + versions.json live)");
+    Console.WriteLine();
+
+    // Only secrets and InstallPath are supplied in code. Identity fields
+    // (MainAppName, ClientVersion, UpdateAppName) are read from
+    // generalupdate.manifest.json by OssStrategy via
+    // AppMetadataDiscoverer.Discover() — same as the standard OSS client flow.
+    await new GeneralUpdateBootstrap()
+        .SetSource(
+            "http://localhost:5000/packages/versions.json",
+            "dfeb5833-975e-4afb-88f1-6278ee9aeff6",
+            installPath: installPath)
+        .SetOption(Option.AppType, AppType.OssUpgrade)
+        .Hooks<UpgradeTestHooks>()
+        .AddListenerMultiDownloadStatistics(OnDownloadStatistics)
+        .AddListenerMultiDownloadCompleted(OnDownloadCompleted)
+        .AddListenerMultiAllDownloadCompleted(OnAllDownloadCompleted)
+        .AddListenerMultiDownloadError(OnDownloadError)
+        .AddListenerException(OnException)
+        .LaunchAsync();
+
+    Console.WriteLine("OSS Upgrade test completed.");
+}
+
+// ═══════════════════════════════════════════════════════════════════
+// Standard Upgrade mode — read IPC config → apply patches → launch main app
+// ═══════════════════════════════════════════════════════════════════
+static async Task RunStandardUpgradeAsync()
 {
     Console.WriteLine("=== GeneralUpdate Upgrade Test ===");
     Console.WriteLine($"Started at {DateTime.Now}");
@@ -26,11 +90,10 @@
 
     Console.WriteLine("Upgrade test completed.");
 }
-catch (Exception ex)
-{
-    Console.WriteLine($"FATAL: {ex}");
-    Environment.Exit(1);
-}
+
+// ═══════════════════════════════════════════════════════════════════
+// Event handlers (shared across both modes)
+// ═══════════════════════════════════════════════════════════════════
 
 static void OnDownloadStatistics(object sender, MultiDownloadStatisticsEventArgs e)
 {
@@ -62,6 +125,10 @@ static void OnException(object sender, ExceptionEventArgs e)
     Console.WriteLine($"[Error] {e.Exception}");
 }
 
+// ═══════════════════════════════════════════════════════════════════
+// Hooks (shared across both modes)
+// ═══════════════════════════════════════════════════════════════════
+
 sealed class UpgradeTestHooks : IUpdateHooks
 {
     public async Task<bool> OnBeforeUpdateAsync(HookContext ctx)
@@ -79,6 +146,8 @@ public async Task OnDownloadCompletedAsync(DownloadContext ctx)
     public async Task OnAfterUpdateAsync(HookContext ctx)
     {
         Console.WriteLine($"[Hook] OnAfterUpdate: {ctx.CurrentVersion} -> {ctx.TargetVersion}");
+        // Manifest ClientVersion is updated by OssStrategy itself via
+        // ManifestInfo.TryUpdateVersion() after decompression.
         await Task.CompletedTask;
     }