coldhighsun · Oct 13, 2026 · Oct 13, 2026
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
@@ -138,31 +138,49 @@ jobs:
           echo "is_prerelease=$($isPrerelease.ToString().ToLower())" >> $env:GITHUB_OUTPUT
         shell: pwsh
 
-      - name: Build portable package
-        run: |
-          $tag = "${{ steps.version.outputs.tag }}"
-          Compress-Archive -Path publish-fx\* -DestinationPath "ManagedDrive-$tag-win-x64-portable.zip"
-        shell: pwsh
-
-      - name: Prepare installer inputs
+      - name: Download WinFsp MSI
+        # Single source of the bundled WinFsp release for the steps below; bump alongside
+        # WinFspPrerequisite.cs, installer/ManagedDrive.iss and Directory.Packages.props.
+        env:
+          WINFSP_TAG: v2.2B5
+          WINFSP_MSI: winfsp-2.2.26286.msi
+          WINFSP_SHA256: 293FFB9BCC0B625C85079FE85FA77F8FE98170ABA51A02AC9C83D58F6C3B0E2F
         run: |
-          Copy-Item -Path publish-fx -Destination installer\publish-fx -Recurse
+          "WINFSP_MSI=$env:WINFSP_MSI" >> $env:GITHUB_ENV
+          "WINFSP_SHA256=$env:WINFSP_SHA256" >> $env:GITHUB_ENV
           Invoke-WebRequest `
-            -Uri "https://github.com/winfsp/winfsp/releases/download/v2.2B4/winfsp-2.2.26215.msi" `
-            -OutFile "installer\winfsp-2.2.26215.msi"
+            -Uri "https://github.com/winfsp/winfsp/releases/download/$env:WINFSP_TAG/$env:WINFSP_MSI" `
+            -OutFile $env:WINFSP_MSI
         shell: pwsh
 
       - name: Verify WinFsp MSI checksum
-        # Pins the download to the exact bytes we've tested against; bump this hash
-        # deliberately (alongside the URL above) when upgrading the bundled WinFsp version.
+        # Pins the download to the exact bytes we've tested against; bump WINFSP_SHA256
+        # deliberately (alongside WINFSP_TAG/WINFSP_MSI above) when upgrading the bundled WinFsp version.
         run: |
-          $expectedHash = "2ECB5C89405488A95BBD8A01875E02C48534FD37BBDFD84488F7590464D65944"
-          $actualHash = (Get-FileHash "installer\winfsp-2.2.26215.msi" -Algorithm SHA256).Hash
+          $expectedHash = $env:WINFSP_SHA256
+          $actualHash = (Get-FileHash $env:WINFSP_MSI -Algorithm SHA256).Hash
           if ($actualHash -ne $expectedHash) {
             throw "WinFsp MSI checksum mismatch: expected $expectedHash, got $actualHash"
           }
         shell: pwsh
 
+      - name: Build portable package
+        # The portable ZIP carries the WinFsp MSI in prerequisites\ so the app can install it offline;
+        # it is removed again afterwards because the Inno Setup installer bundles its own copy.
+        run: |
+          $tag = "${{ steps.version.outputs.tag }}"
+          New-Item -ItemType Directory -Path publish-fx\prerequisites | Out-Null
+          Copy-Item $env:WINFSP_MSI publish-fx\prerequisites\
+          Compress-Archive -Path publish-fx\* -DestinationPath "ManagedDrive-$tag-win-x64-portable.zip"
+          Remove-Item publish-fx\prerequisites -Recurse -Force
+        shell: pwsh
+
+      - name: Prepare installer inputs
+        run: |
+          Copy-Item -Path publish-fx -Destination installer\publish-fx -Recurse
+          Copy-Item $env:WINFSP_MSI installer\
+        shell: pwsh
+
       - name: Install Inno Setup
         # Chocolatey's "innosetup" package tops out at 6.x; JRSoftware.InnoSetup.7 is the
         # separate winget package for Inno Setup 7. "--scope machine" keeps the install

diff --git a/CLAUDE.md b/CLAUDE.md
@@ -23,7 +23,7 @@ dotnet run --project src/ManagedDrive.Cli -- list
 
 The solution file is `ManagedDrive.slnx` (Visual Studio 2022+ format).
 
-**WinFsp prerequisite:** `winfsp-msil.dll` must be present at `C:\Program Files (x86)\WinFsp\bin\`. Install exactly [WinFsp 2.2.26215 (2026 Beta4)](https://github.com/winfsp/winfsp/releases/tag/v2.2B4) before building or running — download the MSI directly; do not use `winget install WinFsp.WinFsp`, as the winget package lags behind this release.
+**WinFsp prerequisite:** `winfsp-msil.dll` must be present at `C:\Program Files (x86)\WinFsp\bin\`. Install exactly [WinFsp 2.2.26286 (2026 Beta5)](https://github.com/winfsp/winfsp/releases/tag/v2.2B5) before building or running — download the MSI directly; do not use `winget install WinFsp.WinFsp`, as the winget package lags behind this release. At startup `WinFspPrerequisite.Check` compares the installed `winfsp-msil.dll` with that version (`RequiredVersion`, the release tag and the MSI SHA256 live there too; bump them together with `winfsp.net`, `installer/ManagedDrive.iss` and the `ci.yml` WinFsp env values); a missing or older version offers `WinFspInstaller` (copies the MSI shipped in the portable ZIP's `prerequisites\`, or downloads it, to `%LOCALAPPDATA%\ManagedDrive\updates`; verifies the SHA256 through a handle that stays open during the run; runs `msiexec` elevated). A newer WinFsp is accepted, a declined update for an older one is remembered per installed/required pair (`AppConfiguration.SkippedWinFspVersion`), and only a missing runtime is fatal.
 
 ## Architecture
 

diff --git a/Directory.Packages.props b/Directory.Packages.props
@@ -9,7 +9,7 @@
     <PackageVersion Include="Microsoft.NET.Test.Sdk" Version="18.10.1" />
     <PackageVersion Include="xunit.v3" Version="4.0.2" />
     <PackageVersion Include="xunit.runner.visualstudio" Version="4.0.1" />
-    <PackageVersion Include="winfsp.net" Version="2.2.26215" />
+    <PackageVersion Include="winfsp.net" Version="2.2.26286" />
     <PackageVersion Include="BenchmarkDotNet" Version="0.15.8" />
     <PackageVersion Include="System.CommandLine" Version="2.0.12" />
     <PackageVersion Include="Spectre.Console" Version="0.57.2" />

diff --git a/README.md b/README.md
@@ -98,7 +98,7 @@ The ZIP also includes `mdrive.exe`, a companion CLI (see [CLI Usage](#cli-usage)
 | Requirement | Notes |
 |---|---|
 | **Windows 10 / 11 (64-bit)** | ARM64 is not currently tested |
-| **[WinFsp 2.2.26215 (2026 Beta4)](https://github.com/winfsp/winfsp/releases/tag/v2.2B4)** | Must be installed before running ManagedDrive. Download the installer directly: [winfsp-2.2.26215.msi](https://github.com/winfsp/winfsp/releases/download/v2.2B4/winfsp-2.2.26215.msi) — do not use `winget install WinFsp.WinFsp`, as the winget package lags behind the latest release. The managed assembly `winfsp-msil.dll` is installed to `C:\Program Files (x86)\WinFsp\bin\` and is referenced by the project automatically. |
+| **[WinFsp 2.2.26286 (2026 Beta5)](https://github.com/winfsp/winfsp/releases/tag/v2.2B5)** | The installer bundles it, and the app offers to download and install it when it is missing or older (a newer version is accepted); the portable ZIP also carries the installer in `prerequisites\`. To install it manually, download the installer directly: [winfsp-2.2.26286.msi](https://github.com/winfsp/winfsp/releases/download/v2.2B5/winfsp-2.2.26286.msi) — do not use `winget install WinFsp.WinFsp`, as the winget package lags behind the latest release. The managed assembly `winfsp-msil.dll` is installed to `C:\Program Files (x86)\WinFsp\bin\` and is referenced by the project automatically. |
 | **[.NET 10 Desktop Runtime](https://dotnet.microsoft.com/download/dotnet/10.0)** | Required for the `-portable` ZIP (framework-dependent). |
 | **.NET 10 SDK** | Required to build. |
 
@@ -307,7 +307,7 @@ ZIP 中还包含 `mdrive.exe`（配套命令行工具，见下方[命令行用
 | 要求 | 说明 |
 |---|---|
 | **Windows 10 / 11（64 位）** | 暂未测试 ARM64 |
-| **[WinFsp 2.2.26215（2026 Beta4）](https://github.com/winfsp/winfsp/releases/tag/v2.2B4)** | 必须安装此版本才能运行 ManagedDrive。请直接下载安装包：[winfsp-2.2.26215.msi](https://github.com/winfsp/winfsp/releases/download/v2.2B4/winfsp-2.2.26215.msi)——不要使用 `winget install WinFsp.WinFsp` 安装，因为该 winget 包更新不及时，落后于最新发布版本。托管程序集 `winfsp-msil.dll` 将安装至 `C:\Program Files (x86)\WinFsp\bin\`，项目会自动引用。 |
+| **[WinFsp 2.2.26286（2026 Beta5）](https://github.com/winfsp/winfsp/releases/tag/v2.2B5)** | 安装程序已内置，应用在检测到缺失或版本过旧时也会提示自动下载安装（更新版本可直接使用），便携版压缩包的 `prerequisites\` 目录同样附带安装包。如需手动安装，请直接下载安装包：[winfsp-2.2.26286.msi](https://github.com/winfsp/winfsp/releases/download/v2.2B5/winfsp-2.2.26286.msi)——不要使用 `winget install WinFsp.WinFsp` 安装，因为该 winget 包更新不及时，落后于最新发布版本。托管程序集 `winfsp-msil.dll` 将安装至 `C:\Program Files (x86)\WinFsp\bin\`，项目会自动引用。 |
 | **[.NET 10 桌面运行时](https://dotnet.microsoft.com/download/dotnet/10.0)** | "绿色版"（框架依赖型）ZIP 需要。 |
 | **.NET 10 SDK** | 编译所需。 |
 

diff --git a/docs/DEVELOPMENT.md b/docs/DEVELOPMENT.md
@@ -11,8 +11,8 @@ Developer-facing documentation for ManagedDrive — building from source, soluti
 ### Getting Started
 
 ```powershell
-# 1. Download and install WinFsp 2.2.26215 (2026 Beta4)
-# https://github.com/winfsp/winfsp/releases/download/v2.2B4/winfsp-2.2.26215.msi
+# 1. Download and install WinFsp 2.2.26286 (2026 Beta5) - or let ManagedDrive offer to install it on first start
+# https://github.com/winfsp/winfsp/releases/download/v2.2B5/winfsp-2.2.26286.msi
 
 # 2. Clone the repository
 git clone https://github.com/coldhighsun/ManagedDrive
@@ -100,8 +100,8 @@ BenchmarkDotNet will prompt you to pick which benchmark class(es) to run (`Seque
 ### 快速开始
 
 ```powershell
-# 1. 下载并安装 WinFsp 2.2.26215（2026 Beta4）
-# https://github.com/winfsp/winfsp/releases/download/v2.2B4/winfsp-2.2.26215.msi
+# 1. 下载并安装 WinFsp 2.2.26286（2026 Beta5）——也可以首次启动时由 ManagedDrive 提示自动安装
+# https://github.com/winfsp/winfsp/releases/download/v2.2B5/winfsp-2.2.26286.msi
 
 # 2. 克隆仓库
 git clone https://github.com/coldhighsun/ManagedDrive

diff --git a/docs/THIRD-PARTY-NOTICES.md b/docs/THIRD-PARTY-NOTICES.md
@@ -4,10 +4,10 @@ ManagedDrive uses the following open-source software.
 
 ## WinFsp
 
-- **Package:** `winfsp.net` 2.2.26215
+- **Package:** `winfsp.net` 2.2.26286
 - **Copyright:** © 2015-2026 Bill Zissimopoulos
 - **License:** Dual-licensed under the GNU General Public License v2 (with a FUSE linking exception) or a commercial license. See [License.txt](https://github.com/winfsp/winfsp/blob/master/License.txt) and [winfsp.dev](https://winfsp.dev/) for the authoritative terms.
-- The `ManagedDrive-Setup-*.exe` installer bundles and redistributes the official, unmodified WinFsp installer (`winfsp-2.2.26215.msi`, downloaded from the [WinFsp v2.2B4 release](https://github.com/winfsp/winfsp/releases/tag/v2.2B4)) so it can be installed automatically alongside ManagedDrive.
+- The `ManagedDrive-Setup-*.exe` installer bundles and redistributes the official, unmodified WinFsp installer (`winfsp-2.2.26286.msi`, downloaded from the [WinFsp v2.2B5 release](https://github.com/winfsp/winfsp/releases/tag/v2.2B5)) so it can be installed automatically alongside ManagedDrive.
 
 ## SharpCompress
 

diff --git a/installer/ManagedDrive.iss b/installer/ManagedDrive.iss
@@ -16,7 +16,9 @@
   #define AppVersionTag "v" + AppVersion
 #endif
 
-#define WinFspMsiName "winfsp-2.2.26215.msi"
+#define WinFspBuild "26286"
+#define WinFspVersion "2.2." + WinFspBuild
+#define WinFspMsiName "winfsp-" + WinFspVersion + ".msi"
 #define HelperServiceName "ManagedDriveHelper"
 #define HelperServiceExeName "ManagedDriveHelper.exe"
 ; Must match App.xaml.cs::SingleInstanceMutexName exactly - this is how Setup detects a running
@@ -93,13 +95,14 @@ var
   // LaunchAppAsUser()'s explorer.exe workaround below exists to avoid.
   LaunchAppCheckBox: TNewCheckBox;
 
-// Mirrors ManagedDrive.App's App.xaml.cs::CheckWinFspPrerequisite() detection:
-// HKLM InstallDir -> <InstallDir>\bin\winfsp-msil.dll must exist with a 2.2.x file version.
+// Mirrors ManagedDrive.App's WinFspPrerequisite.Check() detection: HKLM InstallDir ->
+// <InstallDir>\bin\winfsp-msil.dll must exist with at least the bundled version ({#WinFspVersion}).
+// An older version is replaced by the bundled MSI; a newer one is kept (MSI refuses downgrades).
 function IsWinFspInstalled(): Boolean;
 var
   InstallDir, DllPath: string;
   VersionMS, VersionLS: Cardinal;
-  Major, Minor: Integer;
+  Major, Minor, Build: Cardinal;
 begin
   Result := False;
 
@@ -118,7 +121,8 @@ begin
 
   Major := VersionMS shr 16;
   Minor := VersionMS and $FFFF;
-  Result := (Major = 2) and (Minor = 2);
+  Build := VersionLS shr 16;
+  Result := (Major > 2) or ((Major = 2) and ((Minor > 2) or ((Minor = 2) and (Build >= {#WinFspBuild}))));
 end;
 
 // Mirrors the check dotnet's own bootstrapper uses to detect an installed
@@ -427,7 +431,7 @@ begin
     if not IsWinFspInstalled() then
       InstallWinFspSilently()
     else
-      Log('WinFsp 2.2.x already installed; skipping.');
+      Log('WinFsp {#WinFspVersion} already installed; skipping.');
 
     // Reinstall/upgrade: stop the running service *before* [Files] copies the new
     // ManagedDriveHelper.exe over it. CloseApplicationsFilter/Restart Manager only cover

diff --git a/src/ManagedDrive.App/App.xaml.cs b/src/ManagedDrive.App/App.xaml.cs
@@ -145,7 +145,7 @@ private async void App_Startup(object sender, StartupEventArgs e)
             // Before the splash, so its warning box is not covered by it. Shutdown() only queues the
             // exit; return so nothing below runs — in particular no MainViewModel gets created, so
             // App_Exit has no (empty) disk list to save over the user's settings.
-            if (!CheckWinFspPrerequisite())
+            if (!await CheckWinFspPrerequisiteAsync(_settings, config))
             {
                 Shutdown();
                 return;
@@ -561,30 +561,102 @@ void CountDiskDone(int index)
     private const int AutoMountConcurrency = 2;
 
     /// <summary>
-    /// Verifies WinFsp is installed; if not, tells the user and offers to open its download page.
+    /// Verifies the required WinFsp version is installed; if not, offers to download and install it.
     /// </summary>
     /// <returns>
     /// <c>true</c> if WinFsp is installed and startup can continue; <c>false</c> if the app must exit.
     /// </returns>
-    private static bool CheckWinFspPrerequisite()
+    private static async Task<bool> CheckWinFspPrerequisiteAsync(SettingsStore settings, AppConfiguration config)
     {
-        if (WinFspPrerequisite.IsInstalled())
+        var check = WinFspPrerequisite.Check();
+        if (!WinFspPrerequisite.ShouldPrompt(check, config.SkippedWinFspVersion))
         {
             return true;
         }
 
-        var result = MessageBox.Show(
-            Loc.Get("Msg.WinFspMissingBody"),
-            Loc.Get("Msg.WinFspMissingTitle"),
+        var missing = check.Status == WinFspStatus.Missing;
+
+        var question = missing
+            ? Loc.Format("Msg.WinFspMissingBody", WinFspPrerequisite.RequiredVersionText)
+            : Loc.Format("Msg.WinFspMismatchBody", check.InstalledVersion!, WinFspPrerequisite.RequiredVersionText);
+
+        var answer = MessageBox.Show(
+            question,
+            Loc.Get(missing ? "Msg.WinFspMissingTitle" : "Msg.WinFspTitle"),
             MessageBoxButton.YesNo,
-            MessageBoxImage.Error);
+            missing ? MessageBoxImage.Error : MessageBoxImage.Question);
+
+        // An older build still works; only a missing runtime is fatal. When the user says no, or the update
+        // cannot be done (UAC declined, offline), remember the installed/required pair so it is not asked
+        // about again on every start.
+        void RememberSkip()
+        {
+            if (!missing)
+            {
+                var skipKey = WinFspPrerequisite.SkipKey(check.InstalledVersion!);
+                settings.Update(current => current with { SkippedWinFspVersion = skipKey });
+            }
+        }
 
-        if (result == MessageBoxResult.Yes)
+        if (answer != MessageBoxResult.Yes)
         {
-            Process.Start(new ProcessStartInfo("https://github.com/winfsp/winfsp/releases/tag/v2.2B4") { UseShellExecute = true });
+            RememberSkip();
+            return !missing;
         }
 
-        return false;
+        var installer = WinFspInstaller.CreateDefault();
+        WinFspInstallResult result;
+        System.Windows.Input.Mouse.OverrideCursor = System.Windows.Input.Cursors.Wait;
+        try
+        {
+            result = await installer.InstallAsync();
+        }
+        finally
+        {
+            System.Windows.Input.Mouse.OverrideCursor = null;
+        }
+
+        switch (result)
+        {
+            case WinFspInstallResult.Success:
+                return true;
+            case WinFspInstallResult.RebootRequired:
+                MessageBox.Show(
+                    Loc.Format("Msg.WinFspRebootRequired", WinFspPrerequisite.RequiredVersionText),
+                    Loc.Get("Msg.WinFspTitle"),
+                    MessageBoxButton.OK,
+                    MessageBoxImage.Information);
+                return false;
+            case WinFspInstallResult.Declined:
+                // Nothing changed; explain why a missing runtime still ends the app instead of closing silently.
+                if (missing)
+                {
+                    OfferManualWinFspDownload(Loc.Format("Msg.WinFspDeclined", WinFspPrerequisite.RequiredVersionText));
+                }
+
+                RememberSkip();
+                return !missing;
+            default:
+                Log.Warning("Automatic WinFsp install failed: {Error}", installer.LastError);
+                OfferManualWinFspDownload(Loc.Format("Msg.WinFspInstallFailed", installer.LastError ?? string.Empty));
+                RememberSkip();
+                return !missing;
+        }
+    }
+
+    /// <summary>
+    /// Shows <paramref name="message"/> and opens the WinFsp release page when the user agrees.
+    /// </summary>
+    private static void OfferManualWinFspDownload(string message)
+    {
+        if (MessageBox.Show(
+                message,
+                Loc.Get("Msg.WinFspTitle"),
+                MessageBoxButton.YesNo,
+                MessageBoxImage.Error) == MessageBoxResult.Yes)
+        {
+            Process.Start(new ProcessStartInfo(WinFspPrerequisite.ReleasePageUrl) { UseShellExecute = true });
+        }
     }
 
     /// <summary>