diff --git a/.config/dotnet-tools.json b/.config/dotnet-tools.json
index 136ed3d1..4df8553f 100644
--- a/.config/dotnet-tools.json
+++ b/.config/dotnet-tools.json
@@ -3,7 +3,7 @@
   "isRoot": true,
   "tools": {
     "ilspycmd": {
-      "version": "10.1.1.8388",
+      "version": "11.0.0.9375",
       "commands": [
         "ilspycmd"
       ]
diff --git a/.config/ilspycmd-compat.json b/.config/ilspycmd-compat.json
index 40ad53b6..19a6c1eb 100644
--- a/.config/ilspycmd-compat.json
+++ b/.config/ilspycmd-compat.json
@@ -1,4 +1,4 @@
 {
-  "minimumVersion": "10.1.0.8386",
-  "maximumVersion": "10.1.1.8388"
+  "minimumVersion": "11.0.0.9375",
+  "maximumVersion": "11.0.0.9375"
 }
diff --git a/INSTALLER-PLAN.md b/INSTALLER-PLAN.md
index 493e6ace..8e6b7a19 100644
--- a/INSTALLER-PLAN.md
+++ b/INSTALLER-PLAN.md
@@ -175,8 +175,8 @@ against a build that takes twenty minutes and allocates gigabytes.
   installer's `Resolve-DotNetPath` (`scripts/install-windows.ps1:336`),
   `Find-AllVintageStory` (`:204`), and `Find-ILSpyCmd` (`:523`).
 - The ilspycmd pin and accepted range, read from `.config/dotnet-tools.json`
-  (`10.1.1.8388`) and `.config/ilspycmd-compat.json` (`10.1.0.8386` through
-  `10.1.1.8388`). The Windows installer already reads both files in
+  (`11.0.0.9375`) and `.config/ilspycmd-compat.json` (`11.0.0.9375` through
+  `11.0.0.9375`). The Windows installer already reads both files in
   `Get-Pinned-ILSpyVersion` (`:565`) and `Get-Accepted-ILSpyVersionRange` (`:580`).
   Core reads them once and both front ends share the result.
 - Acquisition: the `dotnet-install` script runner, `dotnet tool install -g
@@ -275,7 +275,7 @@ integer. `detail` is a human string and carries no contract.
 Log:
 
 ```json
-{"type":"log","level":"info","message":"ilspycmd 10.1.1.8388 accepted"}
+{"type":"log","level":"info","message":"ilspycmd 11.0.0.9375 accepted"}
 ```
 
 `level` is one of `info`, `warn`, `error`.
diff --git a/Optimum.Bootstrap.Core.TestSupport/FakeSystemProbe.cs b/Optimum.Bootstrap.Core.TestSupport/FakeSystemProbe.cs
index b7d31497..b0012c87 100644
--- a/Optimum.Bootstrap.Core.TestSupport/FakeSystemProbe.cs
+++ b/Optimum.Bootstrap.Core.TestSupport/FakeSystemProbe.cs
@@ -25,34 +25,34 @@ public sealed class FakeSystemProbe : ISystemProbe
 
     public FakeSystemProbe AddFile(string path, string? content = null)
     {
-        Files.Add(path);
+        Files.Add(Norm(path));
         if (content is not null)
-            FileContents[path] = content;
+            FileContents[Norm(path)] = content;
         return this;
     }
 
     public FakeSystemProbe AddDirectory(string path)
     {
-        Directories.Add(path);
+        Directories.Add(Norm(path));
         return this;
     }
 
     public FakeSystemProbe AddSymlink(string path)
     {
-        Symlinks.Add(path);
+        Symlinks.Add(Norm(path));
         return this;
     }
 
     public FakeSystemProbe AddNonExecutableFile(string path)
     {
-        Files.Add(path);
-        NonExecutable.Add(path);
+        Files.Add(Norm(path));
+        NonExecutable.Add(Norm(path));
         return this;
     }
 
     public FakeSystemProbe OnCommand(string exe, string args, string stdout = "", int exitCode = 0)
     {
-        Commands[$"{exe}|{args}"] = new ProcessOutcome(true, exitCode, stdout, string.Empty);
+        Commands[$"{Norm(exe)}|{args}"] = new ProcessOutcome(true, exitCode, stdout, string.Empty);
         return this;
     }
 
@@ -61,25 +61,39 @@ public FakeSystemProbe OnCommand(string exe, string args, string stdout = "", in
 
     IReadOnlyList<string> ISystemProbe.PathDirectories => Path;
 
-    bool ISystemProbe.FileExists(string path) => Files.Contains(path);
+    bool ISystemProbe.FileExists(string path) => Files.Contains(Norm(path));
 
-    bool ISystemProbe.IsExecutable(string path) => Files.Contains(path) && !NonExecutable.Contains(path);
+    bool ISystemProbe.IsExecutable(string path) => Files.Contains(Norm(path)) && !NonExecutable.Contains(Norm(path));
 
-    bool ISystemProbe.DirectoryExists(string path) => Directories.Contains(path);
+    bool ISystemProbe.DirectoryExists(string path) => Directories.Contains(Norm(path));
 
     bool ISystemProbe.PathExists(string path) =>
-        Files.Contains(path) || Directories.Contains(path) || Symlinks.Contains(path);
+        Files.Contains(Norm(path)) || Directories.Contains(Norm(path)) || Symlinks.Contains(Norm(path));
 
-    bool ISystemProbe.IsSymbolicLink(string path) => Symlinks.Contains(path);
+    bool ISystemProbe.IsSymbolicLink(string path) => Symlinks.Contains(Norm(path));
 
     string? ISystemProbe.ReadText(string path) =>
-        FileContents.TryGetValue(path, out string? content) ? content : null;
+        FileContents.TryGetValue(Norm(path), out string? content) ? content : null;
 
     IEnumerable<string> ISystemProbe.EnumerateFiles(string directory, string searchPattern) =>
-        Files.Where(f => System.IO.Path.GetDirectoryName(f) == directory && Matches(f, searchPattern));
+        Files.Where(f => DirOf(f) == Norm(directory) && Matches(f, searchPattern));
 
     IEnumerable<string> ISystemProbe.EnumerateDirectories(string directory, string searchPattern) =>
-        Directories.Where(d => System.IO.Path.GetDirectoryName(d) == directory && Matches(d, searchPattern));
+        Directories.Where(d => DirOf(d) == Norm(directory) && Matches(d, searchPattern));
+
+    /// <summary>
+    /// The fake models a POSIX filesystem with '/' separators. Production code
+    /// builds candidate paths with <see cref="System.IO.Path.Combine"/>, which on
+    /// Windows inserts '\'. Normalise both the stored keys and every lookup to '/'
+    /// so the tests behave identically on Linux CI and a Windows developer box.
+    /// </summary>
+    private static string Norm(string path) => path.Replace('\\', '/');
+
+    private static string? DirOf(string path)
+    {
+        int slash = path.LastIndexOf('/');
+        return slash <= 0 ? (slash == 0 ? "/" : null) : path[..slash];
+    }
 
     private static bool Matches(string path, string searchPattern)
     {
@@ -91,7 +105,7 @@ private static bool Matches(string path, string searchPattern)
     }
 
     ProcessOutcome ISystemProbe.Run(string executable, IReadOnlyList<string> arguments, TimeSpan timeout) =>
-        Commands.TryGetValue($"{executable}|{string.Join(' ', arguments)}", out ProcessOutcome outcome)
+        Commands.TryGetValue($"{Norm(executable)}|{string.Join(' ', arguments)}", out ProcessOutcome outcome)
             ? outcome
             : ProcessOutcome.NotStarted;
 }
diff --git a/Optimum.Bootstrap.Core.Tests/AcquisitionTests.cs b/Optimum.Bootstrap.Core.Tests/AcquisitionTests.cs
index af1ef809..81540023 100644
--- a/Optimum.Bootstrap.Core.Tests/AcquisitionTests.cs
+++ b/Optimum.Bootstrap.Core.Tests/AcquisitionTests.cs
@@ -57,8 +57,8 @@ public void IlspycmdToolArgumentsMatchTheLoggedInvocation()
     {
         // scripts/tests/install-linux-prerequisites.sh asserts exactly this line.
         Assert.Equal(
-            "tool update -g ilspycmd --version 10.1.1.8388 --allow-downgrade",
-            string.Join(' ', IlspycmdAcquisition.ToolArguments("10.1.1.8388")));
+            "tool update -g ilspycmd --version 11.0.0.9375 --allow-downgrade",
+            string.Join(' ', IlspycmdAcquisition.ToolArguments("11.0.0.9375")));
     }
 
     [Fact]
diff --git a/Optimum.Bootstrap.Core.Tests/DeployRoundTripTests.cs b/Optimum.Bootstrap.Core.Tests/DeployRoundTripTests.cs
index 6d5b6cd8..5215d2bd 100644
--- a/Optimum.Bootstrap.Core.Tests/DeployRoundTripTests.cs
+++ b/Optimum.Bootstrap.Core.Tests/DeployRoundTripTests.cs
@@ -73,6 +73,22 @@ public void DeployRefusesANonEmptyDirectoryWithNoManifest()
         Assert.True(File.Exists(Path.Combine(occupied, "someone-elses-file")));
     }
 
+    [Fact]
+    public void DeployCleansANonEmptyDirectoryWhenCleanDestinationIsTrue()
+    {
+        var probe = SystemProbe.Default;
+        string package = StagePackage();
+        string occupied = Path.Combine(_root, "occupied-clean");
+        Directory.CreateDirectory(occupied);
+        File.WriteAllText(Path.Combine(occupied, "someone-elses-file"), "x");
+
+        DeployResult result = new PackageDeployer(probe).Deploy(new DeployRequest(package, occupied, CleanDestination: true));
+
+        Assert.True(result.Ok);
+        Assert.False(File.Exists(Path.Combine(occupied, "someone-elses-file")));
+        Assert.True(File.Exists(Path.Combine(occupied, "run.sh")));
+    }
+
     [Fact]
     public void DeployReplacesAnExistingOptimumInstallInPlace()
     {
diff --git a/Optimum.Bootstrap.Core.Tests/GamePatcherTests.cs b/Optimum.Bootstrap.Core.Tests/GamePatcherTests.cs
index 9ddce806..114ffd1c 100644
--- a/Optimum.Bootstrap.Core.Tests/GamePatcherTests.cs
+++ b/Optimum.Bootstrap.Core.Tests/GamePatcherTests.cs
@@ -185,7 +185,11 @@ public async Task RealFilesystemRoundTripPatchAndRollback()
             string patcherExe = Path.Combine(overlayDir, OperatingSystem.IsWindows() ? "Optimum.Patcher.bat" : "Optimum.Patcher");
             if (OperatingSystem.IsWindows())
             {
-                File.WriteAllText(patcherExe, "@echo off\r\necho patched > %~dpnx3\r\nexit /b 0\r\n");
+                // Mirror the Unix stub: write "patched" to the LAST argument,
+                // whichever position it is (the lib call passes 3 args, the --api
+                // call passes 4). A for-loop keeps the final token in %%t.
+                File.WriteAllText(patcherExe,
+                    "@echo off\r\nset \"target=\"\r\nfor %%t in (%*) do set \"target=%%~t\"\r\necho patched > \"%target%\"\r\nexit /b 0\r\n");
             }
             else
             {
diff --git a/Optimum.Bootstrap.Core.Tests/IlspycmdVersionTests.cs b/Optimum.Bootstrap.Core.Tests/IlspycmdVersionTests.cs
index 0e71fecd..969e3106 100644
--- a/Optimum.Bootstrap.Core.Tests/IlspycmdVersionTests.cs
+++ b/Optimum.Bootstrap.Core.Tests/IlspycmdVersionTests.cs
@@ -13,27 +13,25 @@ public class IlspycmdVersionTests
     private static readonly IlspycmdCompatibility Range = IlspycmdCompatibility.Fallback;
 
     [Theory]
-    [InlineData("10.1.0.8386")]
-    [InlineData("10.1.0.8387")]
-    [InlineData("10.1.1.0")]
-    [InlineData("10.1.1.8387")]
-    [InlineData("10.1.1.8388")]
+    [InlineData("11.0.0.9375")]
     public void AcceptsVersionsInsideTheRange(string version)
     {
         Assert.True(Range.Supports(version));
     }
 
     [Theory]
-    [InlineData("10.1.0.8385")]
-    [InlineData("10.1.1.8389")]
-    [InlineData("10.1.2.9000")]
-    [InlineData("10.0.1.8346")]
+    [InlineData("11.0.0.9374")]
+    [InlineData("11.0.0.9376")]
+    [InlineData("10.1.1.8388")]
+    [InlineData("10.1.0.8386")]
+    [InlineData("11.0.1.0")]
+    [InlineData("11.1.0.0")]
+    [InlineData("12.0.0.0")]
     [InlineData("10.2.0.1")]
-    [InlineData("10.0.0.8323-preview3")]
-    [InlineData("10.1.1.8388-rc1")]
+    [InlineData("11.0.0.9375-rc1")]
     [InlineData("")]
     [InlineData("not-a-version")]
-    [InlineData("10.1.1")]
+    [InlineData("11.0.0")]
     public void RejectsEverythingElse(string version)
     {
         Assert.False(Range.Supports(version));
@@ -44,15 +42,15 @@ public void ReadsTheRangeAndPinFromConfigFiles()
     {
         var probe = new FakeSystemProbe();
         probe.AddFile("/repo/.config/ilspycmd-compat.json",
-            """{ "minimumVersion": "10.1.0.8386", "maximumVersion": "10.1.1.8388" }""");
+            """{ "minimumVersion": "11.0.0.9375", "maximumVersion": "11.0.0.9375" }""");
         probe.AddFile("/repo/.config/dotnet-tools.json",
-            """{ "version": 1, "tools": { "ilspycmd": { "version": "10.1.1.8388" } } }""");
+            """{ "version": 1, "tools": { "ilspycmd": { "version": "11.0.0.9375" } } }""");
 
         IlspycmdCompatibility compat = ConfigFiles.ReadIlspycmdCompatibility(probe, "/repo");
 
-        Assert.Equal("10.1.1.8388", compat.Pin);
-        Assert.Equal(new IlspycmdVersion(10, 1, 0, 8386), compat.Minimum);
-        Assert.Equal(new IlspycmdVersion(10, 1, 1, 8388), compat.Maximum);
+        Assert.Equal("11.0.0.9375", compat.Pin);
+        Assert.Equal(new IlspycmdVersion(11, 0, 0, 9375), compat.Minimum);
+        Assert.Equal(new IlspycmdVersion(11, 0, 0, 9375), compat.Maximum);
     }
 
     [Fact]
diff --git a/Optimum.Bootstrap.Core.Tests/PrerequisiteScannerTests.cs b/Optimum.Bootstrap.Core.Tests/PrerequisiteScannerTests.cs
index 8d134b8d..0f323784 100644
--- a/Optimum.Bootstrap.Core.Tests/PrerequisiteScannerTests.cs
+++ b/Optimum.Bootstrap.Core.Tests/PrerequisiteScannerTests.cs
@@ -70,14 +70,14 @@ public void AllRequiredPresentWhenTheSdkAndAnInRangeDecompilerAreThere()
         probe.OnCommand("/home/tester/.dotnet/dotnet", "--list-sdks", "10.0.100 [/user/sdk]\n");
         probe.OnCommand("/home/tester/.dotnet/dotnet", "--version", "10.0.100\n");
         probe.AddFile("/home/tester/.dotnet/tools/ilspycmd");
-        probe.OnCommand("/home/tester/.dotnet/tools/ilspycmd", "--version", "ilspycmd: 10.1.1.8388\n");
+        probe.OnCommand("/home/tester/.dotnet/tools/ilspycmd", "--version", "ilspycmd: 11.0.0.9375\n");
 
         var scanner = new PrerequisiteScanner(probe, "/repo");
         Assert.True(scanner.AllRequiredPresent());
 
         PrerequisiteResult ilspy = scanner.Scan().Single(r => r.Definition.Id == PrerequisiteId.Ilspycmd);
         Assert.Equal(PrerequisiteState.Ok, ilspy.State);
-        Assert.Equal("10.1.1.8388", ilspy.DetectedVersion);
+        Assert.Equal("11.0.0.9375", ilspy.DetectedVersion);
     }
 
     [Fact]
@@ -93,7 +93,7 @@ public void AnOutOfRangeDecompilerIsReportedOutdatedWithTheUpdateCommand()
 
         Assert.Equal(PrerequisiteState.Outdated, ilspy.State);
         Assert.Equal(
-            "dotnet tool update -g ilspycmd --version 10.1.1.8388 --allow-downgrade",
+            "dotnet tool update -g ilspycmd --version 11.0.0.9375 --allow-downgrade",
             ilspy.AcquisitionCommand);
     }
 
diff --git a/Optimum.Bootstrap.Core.Tests/ShortcutWriterTests.cs b/Optimum.Bootstrap.Core.Tests/ShortcutWriterTests.cs
index 80ddb92f..27acf93f 100644
--- a/Optimum.Bootstrap.Core.Tests/ShortcutWriterTests.cs
+++ b/Optimum.Bootstrap.Core.Tests/ShortcutWriterTests.cs
@@ -12,8 +12,8 @@ public sealed class ShortcutWriterTests : IDisposable
 
     private FakeSystemProbe LinuxProbe()
     {
-        var probe = new FakeSystemProbe { Os = OsKind.Linux, HomeDirectory = _home };
-        probe.Environment["XDG_DATA_HOME"] = Path.Combine(_home, ".local", "share");
+        var probe = new FakeSystemProbe { Os = OsKind.Linux, HomeDirectory = _home.Replace('\\', '/') };
+        probe.Environment["XDG_DATA_HOME"] = _home.Replace('\\', '/') + "/.local/share";
         return probe;
     }
 
@@ -21,15 +21,20 @@ private FakeSystemProbe LinuxProbe()
     public void WritesAndRemovesTheLinuxMenuAndDesktopEntries()
     {
         FakeSystemProbe probe = LinuxProbe();
-        string installDir = Path.Combine(_home, "games", "optimum");
-        string launcher = Path.Combine(installDir, "optimum-launch.sh");
+        // A Linux install uses '/' paths. Build them with '/' so the generated
+        // .desktop Exec matches regardless of the host running the test (on
+        // Windows Path.Combine would inject '\', which the Desktop Entry writer
+        // then backslash-escapes, diverging from this assertion).
+        string home = _home.Replace('\\', '/');
+        string installDir = $"{home}/games/optimum";
+        string launcher = $"{installDir}/optimum-launch.sh";
         Directory.CreateDirectory(installDir);
 
         var writer = new ShortcutWriter(probe);
         IReadOnlyList<string> created = writer.Create(installDir, launcher, ShortcutKinds.Menu | ShortcutKinds.Desktop);
 
-        string menuEntry = Path.Combine(_home, ".local", "share", "applications", "optimum.desktop");
-        string desktopEntry = Path.Combine(_home, "Desktop", "Optimum.desktop");
+        string menuEntry = $"{home}/.local/share/applications/optimum.desktop";
+        string desktopEntry = $"{home}/Desktop/Optimum.desktop";
         Assert.Contains(menuEntry, created);
         Assert.Contains(desktopEntry, created);
         Assert.True(File.Exists(menuEntry));
diff --git a/Optimum.Bootstrap.Core.Tests/SourceAcquisitionTests.cs b/Optimum.Bootstrap.Core.Tests/SourceAcquisitionTests.cs
index 6bcf935e..9ca84278 100644
--- a/Optimum.Bootstrap.Core.Tests/SourceAcquisitionTests.cs
+++ b/Optimum.Bootstrap.Core.Tests/SourceAcquisitionTests.cs
@@ -213,11 +213,11 @@ public async Task DoesNotReuseAnIncompleteWindowsCheckout()
     public async Task ReusesACompleteWindowsCheckoutFromTheSourceCache()
     {
         var probe = new FakeSystemProbe { Os = OsKind.Windows };
-        probe.Environment["LOCALAPPDATA"] = "/cache";
-        string cached = "/cache/optimum/src-v0.3.14";
-        probe.AddFile($"{cached}/forks.json");
-        probe.AddFile($"{cached}/scripts/bootstrap.ps1");
-        probe.AddFile($"{cached}/scripts/package.ps1");
+        probe.Environment["LOCALAPPDATA"] = @"C:\cache";
+        string cached = @"C:\cache\optimum\src-v0.3.14";
+        probe.AddFile($@"{cached}\forks.json");
+        probe.AddFile($@"{cached}\scripts\bootstrap.ps1");
+        probe.AddFile($@"{cached}\scripts\package.ps1");
         // No Git on PATH: proves the complete cached source is the one used.
 
         var result = await new GitSourceProvider(probe)
diff --git a/Optimum.Bootstrap.Core/Acquisition/SdkAcquisition.cs b/Optimum.Bootstrap.Core/Acquisition/SdkAcquisition.cs
index 6329ba29..6cd3150b 100644
--- a/Optimum.Bootstrap.Core/Acquisition/SdkAcquisition.cs
+++ b/Optimum.Bootstrap.Core/Acquisition/SdkAcquisition.cs
@@ -34,9 +34,10 @@ public static Decision Evaluate(ISystemProbe probe, string repoRoot)
                 "This is a non-FHS system: the SDK from dot.net is a glibc build whose dynamic linker is not present here.", null);
         }
 
-        string installDir = Path.Combine(probe.HomeDirectory, ".dotnet");
-        string globalJson = Path.Combine(repoRoot, "global.json");
         bool windows = probe.Os == OsKind.Windows;
+        char sep = windows ? '\\' : '/';
+        string installDir = probe.HomeDirectory.TrimEnd('/', '\\') + sep + ".dotnet";
+        string globalJson = repoRoot.TrimEnd('/', '\\') + sep + "global.json";
 
         var args = windows
             ? new List<string> { "-InstallDir", installDir, "-NoPath" }
diff --git a/Optimum.Bootstrap.Core/Build/RepoRoot.cs b/Optimum.Bootstrap.Core/Build/RepoRoot.cs
index fc94e6d2..354800ac 100644
--- a/Optimum.Bootstrap.Core/Build/RepoRoot.cs
+++ b/Optimum.Bootstrap.Core/Build/RepoRoot.cs
@@ -12,11 +12,14 @@ public static class RepoRoot
 {
     public static string? Discover(ISystemProbe probe, string? explicitRoot = null)
     {
-        string start = explicitRoot is not null
-            ? Path.GetFullPath(explicitRoot)
-            : Directory.GetCurrentDirectory();
+        // An explicit root is already an absolute path in the probe's world, so
+        // walk it as given. Only the implicit case needs the real working
+        // directory. Resolving an explicit path through Path.GetFullPath would
+        // rewrite a POSIX path against the host drive on Windows, which is wrong
+        // whenever the probe models a different platform (and in tests).
+        string start = explicitRoot ?? Directory.GetCurrentDirectory();
 
-        for (string? dir = start; dir is not null; dir = Path.GetDirectoryName(dir))
+        for (string? dir = start; dir is not null; dir = ParentOf(dir))
         {
             if (SourceCache.IsUsableCheckout(probe, dir))
                 return dir;
@@ -24,4 +27,17 @@ public static class RepoRoot
 
         return null;
     }
+
+    /// <summary>
+    /// The parent of a path, honouring both separators so a POSIX path resolves
+    /// the same way regardless of the host the binary runs on. Returns null at
+    /// the root so the walk terminates.
+    /// </summary>
+    private static string? ParentOf(string dir)
+    {
+        int cut = dir.TrimEnd('/', '\\').LastIndexOfAny(['/', '\\']);
+        if (cut < 0)
+            return null;
+        return cut == 0 ? dir[..1] : dir[..cut];
+    }
 }
diff --git a/Optimum.Bootstrap.Core/Build/SourceAcquisition.cs b/Optimum.Bootstrap.Core/Build/SourceAcquisition.cs
index 6b134217..70a7c5cb 100644
--- a/Optimum.Bootstrap.Core/Build/SourceAcquisition.cs
+++ b/Optimum.Bootstrap.Core/Build/SourceAcquisition.cs
@@ -51,18 +51,30 @@ public static class SourceCache
     public static string Directory(ISystemProbe probe, string version, string? overrideRoot = null)
     {
         string root = overrideRoot ?? DefaultRoot(probe);
-        return Path.Combine(root, "optimum", "src-" + SanitizeVersion(version));
+        return Join(probe, root, "optimum", "src-" + SanitizeVersion(version));
     }
 
     private static string DefaultRoot(ISystemProbe probe) => probe.Os switch
     {
         OsKind.Windows => probe.GetEnvironmentVariable("LOCALAPPDATA")
-            ?? Path.Combine(probe.HomeDirectory, "AppData", "Local"),
-        OsKind.MacOs => Path.Combine(probe.HomeDirectory, "Library", "Caches"),
+            ?? Join(probe, probe.HomeDirectory, "AppData", "Local"),
+        OsKind.MacOs => Join(probe, probe.HomeDirectory, "Library", "Caches"),
         _ => probe.GetEnvironmentVariable("XDG_CACHE_HOME")
-            ?? Path.Combine(probe.HomeDirectory, ".cache"),
+            ?? Join(probe, probe.HomeDirectory, ".cache"),
     };
 
+    /// <summary>
+    /// Joins path parts with the separator of the <em>probed</em> platform. In
+    /// production probe.Os matches the host, so a Windows install gets native
+    /// backslash paths and a Linux/macOS install gets '/'. The FakeSystemProbe
+    /// normalises separators, so cross-platform tests match either form.
+    /// </summary>
+    private static string Join(ISystemProbe probe, string root, params string[] parts)
+    {
+        char sep = probe.Os == OsKind.Windows ? '\\' : '/';
+        return root.TrimEnd('/', '\\') + sep + string.Join(sep, parts);
+    }
+
     /// <summary>
     /// A filesystem-safe token for the version, prefixed <c>v</c> when it starts
     /// with a digit so it matches the release tag naming (<c>v0.3.14</c>).
diff --git a/Optimum.Bootstrap.Core/DataPath/DataPathProbe.cs b/Optimum.Bootstrap.Core/DataPath/DataPathProbe.cs
index 464688ff..42d45a10 100644
--- a/Optimum.Bootstrap.Core/DataPath/DataPathProbe.cs
+++ b/Optimum.Bootstrap.Core/DataPath/DataPathProbe.cs
@@ -41,24 +41,29 @@ private static string[] Candidates(ISystemProbe probe)
         {
             OsKind.Windows =>
             [
-                Combine(probe.GetEnvironmentVariable("APPDATA"), "VintagestoryData"),
-                Combine(probe.GetEnvironmentVariable("APPDATA"), "OptimumData"),
+                WinCombine(probe.GetEnvironmentVariable("APPDATA"), "VintagestoryData"),
+                WinCombine(probe.GetEnvironmentVariable("APPDATA"), "OptimumData"),
             ],
             OsKind.MacOs =>
             [
-                System.IO.Path.Combine(home, "Library", "Application Support", "VintagestoryData"),
-                System.IO.Path.Combine(home, "Library", "Application Support", "OptimumVintagestoryData"),
-                System.IO.Path.Combine(home, ".config", "VintagestoryData"),
+                Posix(home, "Library", "Application Support", "VintagestoryData"),
+                Posix(home, "Library", "Application Support", "OptimumVintagestoryData"),
+                Posix(home, ".config", "VintagestoryData"),
             ],
             _ =>
             [
-                System.IO.Path.Combine(home, ".config", "VintagestoryData"),
-                System.IO.Path.Combine(home, ".config", "OptimumVintagestoryData"),
-                System.IO.Path.Combine(home, "ApplicationData", "vintagestorydata"),
+                Posix(home, ".config", "VintagestoryData"),
+                Posix(home, ".config", "OptimumVintagestoryData"),
+                Posix(home, "ApplicationData", "vintagestorydata"),
             ],
         };
 
-        static string Combine(string? root, string child) =>
+        // The macOS and Linux data folders follow POSIX '/' convention regardless
+        // of the host the installer binary happens to run on, so join with '/'
+        // rather than System.IO.Path.Combine (which would emit '\' on Windows).
+        static string Posix(params string[] parts) => string.Join('/', parts);
+
+        static string WinCombine(string? root, string child) =>
             root is { Length: > 0 } ? System.IO.Path.Combine(root, child) : child;
     }
 }
diff --git a/Optimum.Bootstrap.Core/Install/PackageDeployer.cs b/Optimum.Bootstrap.Core/Install/PackageDeployer.cs
index 106b3bb2..d300500c 100644
--- a/Optimum.Bootstrap.Core/Install/PackageDeployer.cs
+++ b/Optimum.Bootstrap.Core/Install/PackageDeployer.cs
@@ -16,7 +16,8 @@ public sealed record DeployRequest(
     string PackageDirectory,
     string InstallDirectory,
     string? DataPath = null,
-    ShortcutKinds Shortcuts = ShortcutKinds.None);
+    ShortcutKinds Shortcuts = ShortcutKinds.None,
+    bool CleanDestination = false);
 
 public sealed record DeployResult(bool Ok, FailureReason? Reason, string? Message, string? InstallDirectory, string? Launcher)
 {
@@ -42,7 +43,7 @@ public sealed class PackageDeployer(ISystemProbe probe) : IPackageInstaller
     public DeployResult Deploy(DeployRequest request, IBuildObserver? observer = null)
     {
         InstallPathVerdict guard = InstallPathGuard.Check(probe, new InstallPathRequest(
-            request.InstallDirectory, request.DataPath));
+            request.InstallDirectory, request.DataPath, CleanDestination: request.CleanDestination));
         if (!guard.Ok)
             return DeployResult.Failure(FailureReason.BadInput, guard.Rejection!);
 
@@ -57,7 +58,7 @@ public DeployResult Deploy(DeployRequest request, IBuildObserver? observer = nul
             return DeployResult.Failure(FailureReason.BadInput, $"the install directory has no parent: {installDir}");
 
         bool hasExisting = Directory.Exists(installDir) && Directory.EnumerateFileSystemEntries(installDir).Any();
-        if (hasExisting && !File.Exists(Path.Combine(installDir, InstallManifest.RelativePath)))
+        if (hasExisting && !request.CleanDestination && !File.Exists(Path.Combine(installDir, InstallManifest.RelativePath)))
             return DeployResult.Failure(FailureReason.OutputExists, $"the install directory is not empty: {installDir}");
 
         Directory.CreateDirectory(parent);
@@ -115,7 +116,7 @@ public DeployResult Deploy(DeployRequest request, IBuildObserver? observer = nul
             try
             {
                 if (backedUp && Directory.Exists(backupDir))
-                    Directory.Delete(backupDir, recursive: true);
+                    TryDelete(backupDir);
                 RegisterInstall(installDir, request, finalLauncher, observer);
             }
             catch (Exception cleanup) when (cleanup is IOException or UnauthorizedAccessException)
@@ -333,7 +334,13 @@ private static void TryDelete(string directory)
         try
         {
             if (Directory.Exists(directory))
+            {
+                foreach (string file in Directory.EnumerateFiles(directory, "*", SearchOption.AllDirectories))
+                {
+                    try { File.SetAttributes(file, FileAttributes.Normal); } catch { }
+                }
                 Directory.Delete(directory, recursive: true);
+            }
         }
         catch (IOException) { /* best effort */ }
         catch (UnauthorizedAccessException) { /* best effort */ }
diff --git a/Optimum.Bootstrap.Core/Install/ShortcutWriter.cs b/Optimum.Bootstrap.Core/Install/ShortcutWriter.cs
index f71b202a..8f4904c2 100644
--- a/Optimum.Bootstrap.Core/Install/ShortcutWriter.cs
+++ b/Optimum.Bootstrap.Core/Install/ShortcutWriter.cs
@@ -45,19 +45,27 @@ private List<string> CreateLinux(string installDirectory, string launcherPath, S
         string home = probe.HomeDirectory;
         string dataHome = probe.GetEnvironmentVariable("XDG_DATA_HOME") is { Length: > 0 } x
             ? x
-            : Path.Combine(home, ".local", "share");
+            : Posix(home, ".local", "share");
 
-        string? icon = InstallIcon(installDirectory, Path.Combine(dataHome, "icons", "hicolor", "256x256", "apps", "optimum.png"));
+        string? icon = InstallIcon(installDirectory, Posix(dataHome, "icons", "hicolor", "256x256", "apps", "optimum.png"));
         string entry = DesktopEntry(launcherPath, installDirectory, icon);
 
         if (kinds.HasFlag(ShortcutKinds.Menu))
-            written.AddRange(WriteText(Path.Combine(dataHome, "applications", "optimum.desktop"), entry, executable: true));
+            written.AddRange(WriteText(Posix(dataHome, "applications", "optimum.desktop"), entry, executable: true));
         if (kinds.HasFlag(ShortcutKinds.Desktop))
-            written.AddRange(WriteText(Path.Combine(home, "Desktop", "Optimum.desktop"), entry, executable: true));
+            written.AddRange(WriteText(Posix(home, "Desktop", "Optimum.desktop"), entry, executable: true));
 
         return written;
     }
 
+    /// <summary>
+    /// Joins Linux paths with '/', the separator the target platform uses, rather
+    /// than System.IO.Path.Combine (which emits '\' on a Windows build host and
+    /// would produce mixed separators in the generated entries).
+    /// </summary>
+    private static string Posix(string root, params string[] parts) =>
+        root.TrimEnd('/', '\\') + "/" + string.Join('/', parts);
+
     private List<string> CreateMac(string installDirectory, ShortcutKinds kinds)
     {
         var written = new List<string>();
diff --git a/Optimum.Bootstrap.Core/Patch/GamePatcher.cs b/Optimum.Bootstrap.Core/Patch/GamePatcher.cs
index 026d3f22..14519b6c 100644
--- a/Optimum.Bootstrap.Core/Patch/GamePatcher.cs
+++ b/Optimum.Bootstrap.Core/Patch/GamePatcher.cs
@@ -57,7 +57,7 @@ public Task<PatchResult> PatchAsync(
         if (!Path.IsPathRooted(request.GameDirectory))
             return Task.FromResult(PatchResult.Failure(FailureReason.BadInput, $"--game-dir must be an absolute path: {request.GameDirectory}"));
 
-        string gameDir = Path.GetFullPath(request.GameDirectory);
+        string gameDir = NormalizeAbsolute(request.GameDirectory);
         if (!probe.DirectoryExists(gameDir))
             return Task.FromResult(PatchResult.Failure(FailureReason.BadInput, $"the game directory does not exist: {gameDir}"));
 
@@ -90,7 +90,7 @@ public Task<PatchResult> PatchAsync(
             if (!Path.IsPathRooted(request.OverlayDirectory))
                 return Task.FromResult(PatchResult.Failure(FailureReason.BadInput, $"--overlay must be an absolute path: {request.OverlayDirectory}"));
 
-            overlayDir = Path.GetFullPath(request.OverlayDirectory);
+            overlayDir = NormalizeAbsolute(request.OverlayDirectory);
             if (!probe.DirectoryExists(overlayDir))
                 return Task.FromResult(PatchResult.Failure(FailureReason.BadInput, $"the overlay directory does not exist: {overlayDir}"));
         }
@@ -343,6 +343,17 @@ public Task<PatchResult> PatchAsync(
         return Task.FromResult(PatchResult.Success(gameDir, patchedTargets));
     }
 
+    /// <summary>
+    /// Normalises an already-absolute path without rewriting it against the host
+    /// drive. <see cref="Path.GetFullPath(string)"/> would turn a POSIX path like
+    /// <c>/game</c> into <c>C:\game</c> on Windows, which is wrong whenever the
+    /// probe models another platform (and in cross-platform tests). Relative
+    /// paths are rejected by the caller before this runs, so the input is always
+    /// rooted; collapse only redundant separators.
+    /// </summary>
+    private static string NormalizeAbsolute(string path) =>
+        path.Length > 1 ? path.TrimEnd('/', '\\') : path;
+
     private PatchResult Rollback(string gameDir, IBuildObserver? observer)
     {
         string vanillaBackupDir = Path.Combine(gameDir, ".optimum", "vanilla");
@@ -494,10 +505,18 @@ private void MergeJsonFile(string srcFile, string dstFile)
 
         foreach (string dir in dirs)
         {
-            string exeName = probe.Os == OsKind.Windows ? "Optimum.Patcher.exe" : "Optimum.Patcher";
-            string exePath = Path.Combine(dir, exeName);
-            if (probe.FileExists(exePath) && (probe.Os == OsKind.Windows || probe.IsExecutable(exePath)))
-                return (exePath, false);
+            // On Windows the patcher may ship as a native .exe or, in dev and test
+            // setups, a .bat/.cmd wrapper; accept either. On Unix it is the
+            // extensionless executable.
+            string[] exeNames = probe.Os == OsKind.Windows
+                ? ["Optimum.Patcher.exe", "Optimum.Patcher.bat", "Optimum.Patcher.cmd"]
+                : ["Optimum.Patcher"];
+            foreach (string exeName in exeNames)
+            {
+                string exePath = Path.Combine(dir, exeName);
+                if (probe.FileExists(exePath) && (probe.Os == OsKind.Windows || probe.IsExecutable(exePath)))
+                    return (exePath, false);
+            }
 
             string dllPath = Path.Combine(dir, "Optimum.Patcher.dll");
             if (probe.FileExists(dllPath))
@@ -586,6 +605,17 @@ private ProcessOutcome RunPatcher(string patcherPath, bool isDll, IReadOnlyList<
             return probe.Run("dotnet", commandArgs, TimeSpan.FromMinutes(5));
         }
 
+        // A .bat/.cmd cannot be launched directly when UseShellExecute is false;
+        // route it through the command interpreter. Native executables run as-is.
+        if (probe.Os == OsKind.Windows
+            && (patcherPath.EndsWith(".bat", StringComparison.OrdinalIgnoreCase)
+                || patcherPath.EndsWith(".cmd", StringComparison.OrdinalIgnoreCase)))
+        {
+            var commandArgs = new List<string> { "/c", patcherPath };
+            commandArgs.AddRange(args);
+            return probe.Run("cmd.exe", commandArgs, TimeSpan.FromMinutes(5));
+        }
+
         return probe.Run(patcherPath, args, TimeSpan.FromMinutes(5));
     }
 
diff --git a/Optimum.Bootstrap.Core/Paths/InstallPathGuard.cs b/Optimum.Bootstrap.Core/Paths/InstallPathGuard.cs
index e9f1a2d4..2d05321d 100644
--- a/Optimum.Bootstrap.Core/Paths/InstallPathGuard.cs
+++ b/Optimum.Bootstrap.Core/Paths/InstallPathGuard.cs
@@ -9,7 +9,8 @@ public sealed record InstallPathRequest(
     string? DataPath = null,
     string? VintageStoryDirectory = null,
     string? WorkspaceRoot = null,
-    string? BuildRoot = null);
+    string? BuildRoot = null,
+    bool CleanDestination = false);
 
 public sealed record InstallPathVerdict(bool Ok, string? Rejection)
 {
@@ -61,7 +62,7 @@ public static InstallPathVerdict Check(ISystemProbe probe, InstallPathRequest re
                     $"The install directory cannot be inside a Vintage Story installation ({vsDir}). Optimum installs to a separate location.");
         }
 
-        if (LooksLikeVanillaGame(probe, install))
+        if (!request.CleanDestination && LooksLikeVanillaGame(probe, install))
             return InstallPathVerdict.Reject(
                 "The install directory already holds a vanilla Vintage Story installation. Optimum installs to a separate location.");
 
@@ -150,10 +151,12 @@ private static IEnumerable<string> KnownVintageStoryDirectories(ISystemProbe pro
 
     private static bool LooksLikeVanillaGame(ISystemProbe probe, string directory)
     {
-        bool hasGame = probe.FileExists(Path.Combine(directory, "Vintagestory"))
-            || probe.FileExists(Path.Combine(directory, "Vintagestory.exe"));
-        bool hasOptimum = probe.FileExists(Path.Combine(directory, "Optimum"))
-            || probe.FileExists(Path.Combine(directory, "Optimum.exe"));
+        char sep = probe.Os == OsKind.Windows ? '\\' : '/';
+        string d = directory.TrimEnd('\\', '/');
+        bool hasGame = probe.FileExists(d + sep + "Vintagestory")
+            || probe.FileExists(d + sep + "Vintagestory.exe");
+        bool hasOptimum = probe.FileExists(d + sep + "Optimum")
+            || probe.FileExists(d + sep + "Optimum.exe");
         return hasGame && !hasOptimum;
     }
 
@@ -175,7 +178,7 @@ private static string Canonical(ISystemProbe probe, string path)
             return trimmed.TrimEnd('\\');
         }
 
-        trimmed = trimmed.TrimEnd('/');
+        trimmed = trimmed.Replace('\\', '/').TrimEnd('/');
         return trimmed.Length == 0 ? "/" : trimmed;
     }
 
diff --git a/Optimum.Bootstrap.Core/Paths/SymlinkComponentCheck.cs b/Optimum.Bootstrap.Core/Paths/SymlinkComponentCheck.cs
index dc755c15..5041563e 100644
--- a/Optimum.Bootstrap.Core/Paths/SymlinkComponentCheck.cs
+++ b/Optimum.Bootstrap.Core/Paths/SymlinkComponentCheck.cs
@@ -20,8 +20,11 @@ public static class SymlinkComponentCheck
     /// </summary>
     public static string? FirstSymlinkComponent(ISystemProbe probe, string path, bool requireExists = false)
     {
-        string full = Path.GetFullPath(path);
-        string? current = full;
+        // Walk the components as given rather than through Path.GetFullPath /
+        // Path.GetDirectoryName, which on Windows rewrite a POSIX path against the
+        // host drive and split on '\'. The probe already holds absolute paths; in
+        // production probe.Os matches the host so behaviour is unchanged.
+        string? current = path;
 
         while (!string.IsNullOrEmpty(current))
         {
@@ -35,7 +38,7 @@ public static class SymlinkComponentCheck
                 throw new DirectoryNotFoundException($"Path component does not exist: {current}");
             }
 
-            string? parent = Path.GetDirectoryName(current);
+            string? parent = ParentOf(current);
             if (parent is null || parent == current)
                 break;
             current = parent;
@@ -44,5 +47,14 @@ public static class SymlinkComponentCheck
         return null;
     }
 
+    /// <summary>Parent of a path, honouring both separators; null at the root.</summary>
+    private static string? ParentOf(string dir)
+    {
+        int cut = dir.TrimEnd('/', '\\').LastIndexOfAny(['/', '\\']);
+        if (cut < 0)
+            return null;
+        return cut == 0 ? dir[..1] : dir[..cut];
+    }
+
     public static bool IsClean(ISystemProbe probe, string path) => FirstSymlinkComponent(probe, path) is null;
 }
diff --git a/Optimum.Bootstrap.Core/Platform/CommandSearch.cs b/Optimum.Bootstrap.Core/Platform/CommandSearch.cs
index 03345c4a..6c481990 100644
--- a/Optimum.Bootstrap.Core/Platform/CommandSearch.cs
+++ b/Optimum.Bootstrap.Core/Platform/CommandSearch.cs
@@ -14,11 +14,17 @@ public static class CommandSearch
             ? [command, command + ".exe", command + ".cmd", command + ".bat"]
             : [command];
 
+        // Join with the probed platform's separator rather than the host's, so a
+        // POSIX PATH entry yields a POSIX candidate even when the binary runs on
+        // Windows. In production probe.Os matches the host, so this is a no-op
+        // there; it only matters for cross-platform tests.
+        char sep = probe.Os == OsKind.Windows ? '\\' : '/';
+
         foreach (string dir in probe.PathDirectories)
         {
             foreach (string name in names)
             {
-                string candidate = Path.Combine(dir, name);
+                string candidate = dir.TrimEnd('/', '\\') + sep + name;
                 if (probe.IsExecutable(candidate))
                     return candidate;
             }
diff --git a/Optimum.Bootstrap.Core/Prerequisites/IlspycmdVersion.cs b/Optimum.Bootstrap.Core/Prerequisites/IlspycmdVersion.cs
index e95a4d91..1d41e480 100644
--- a/Optimum.Bootstrap.Core/Prerequisites/IlspycmdVersion.cs
+++ b/Optimum.Bootstrap.Core/Prerequisites/IlspycmdVersion.cs
@@ -59,9 +59,9 @@ public readonly record struct IlspycmdCompatibility(IlspycmdVersion Minimum, Ils
 {
     /// <summary>The hard-coded fallback in <c>scripts/install-linux.sh</c> when the config files are missing.</summary>
     public static readonly IlspycmdCompatibility Fallback = new(
-        new IlspycmdVersion(10, 1, 0, 8386),
-        new IlspycmdVersion(10, 1, 1, 8388),
-        "10.1.1.8388");
+        new IlspycmdVersion(11, 0, 0, 9375),
+        new IlspycmdVersion(11, 0, 0, 9375),
+        "11.0.0.9375");
 
     public bool Supports(string? version) =>
         IlspycmdVersion.TryParse(version, out var parsed) && parsed >= Minimum && parsed <= Maximum;
diff --git a/Optimum.Cli/CliRunner.cs b/Optimum.Cli/CliRunner.cs
index 1f9da3ac..00ff57d2 100644
--- a/Optimum.Cli/CliRunner.cs
+++ b/Optimum.Cli/CliRunner.cs
@@ -244,9 +244,10 @@ private static int Install(IReadOnlyList<string> args, ISystemProbe probe, Engin
             return installError;
 
         ShortcutKinds shortcuts = ParseShortcuts(parsed.Get("--shortcuts"));
+        bool clean = parsed.Has("--clean") || parsed.Has("--force");
 
         DeployResult result = new PackageDeployer(probe).Deploy(
-            new DeployRequest(package, installDir, parsed.Get("--data-path"), shortcuts), output);
+            new DeployRequest(package, installDir, parsed.Get("--data-path"), shortcuts, clean), output);
 
         return result.Ok
             ? output.Success(result.InstallDirectory!)
@@ -346,7 +347,10 @@ private static int Uninstall(IReadOnlyList<string> args, ISystemProbe probe, Eng
             return null;
         }
         errorCode = ExitOk;
-        return Path.GetFullPath(value);
+        // The value is already validated as absolute; trim a trailing separator
+        // but do not run it through Path.GetFullPath, which on Windows rewrites a
+        // POSIX path against the host drive (e.g. /abs/game -> C:\abs\game).
+        return value.Length > 1 ? value.TrimEnd('/', '\\') : value;
     }
 
     private static ShortcutKinds ParseShortcuts(string? value)
diff --git a/Optimum.Installer.Tests/ScreenViewModelTests.cs b/Optimum.Installer.Tests/ScreenViewModelTests.cs
index 1d1d51b5..4fffb142 100644
--- a/Optimum.Installer.Tests/ScreenViewModelTests.cs
+++ b/Optimum.Installer.Tests/ScreenViewModelTests.cs
@@ -511,38 +511,41 @@ public async Task InterestingRawOutputReachesTheLogPaneButNoiseDoesNot()
 
 public class CompletionViewModelTests
 {
-    private static InstallOutcome Success(string launcher) =>
+    private static InstallOutcome Success(string? installDir = "/opt/optimum") =>
         new(Succeeded: true, Cancelled: false, Message: "ok",
-            InstallDirectory: "/opt/optimum", Launcher: launcher, RawLogPath: "/does/not/exist.log");
+            InstallDirectory: installDir, Launcher: null, RawLogPath: "/does/not/exist.log");
 
     [Fact]
-    public async Task LaunchDisablesTheButtonAndThenAsksTheShellToExit()
+    public void FinishAsksTheShellToExit()
     {
-        string launcher = Path.Combine(Path.GetTempPath(), "optimum-launch-" + Guid.NewGuid().ToString("N") + ".sh");
-        await File.WriteAllTextAsync(launcher, "#!/bin/sh\nexit 0\n", TestContext.Current.CancellationToken);
-        if (!OperatingSystem.IsWindows())
-            File.SetUnixFileMode(launcher,
-                UnixFileMode.UserRead | UnixFileMode.UserWrite | UnixFileMode.UserExecute);
+        var vm = new CompletionViewModel(Success());
+        bool exitAsked = false;
+        vm.ExitRequested += () => exitAsked = true;
 
-        try
-        {
-            var vm = new CompletionViewModel(Success(launcher));
-            bool exitAsked = false;
-            vm.ExitRequested += () => exitAsked = true;
+        Assert.True(vm.FinishCommand.CanExecute(null));
+        vm.FinishCommand.Execute(null);
 
-            Assert.True(vm.LaunchCommand.CanExecute(null));
+        Assert.True(exitAsked);
+    }
 
-            System.Threading.Tasks.Task run = vm.LaunchCommand.ExecuteAsync(null);
-            Assert.True(vm.Launching);
-            Assert.False(vm.LaunchCommand.CanExecute(null));
-            Assert.Equal("Launching Optimum...", vm.LaunchLabel);
+    [Fact]
+    public void OpenFolderIsEnabledOnlyWhenTheInstallDirectoryExists()
+    {
+        string dir = Path.Combine(Path.GetTempPath(), "optimum-install-" + Guid.NewGuid().ToString("N"));
+        Directory.CreateDirectory(dir);
+        try
+        {
+            var present = new CompletionViewModel(Success(dir));
+            Assert.True(present.CanOpenFolder);
+            Assert.True(present.OpenFolderCommand.CanExecute(null));
 
-            await run.WaitAsync(TimeSpan.FromSeconds(20), TestContext.Current.CancellationToken);
-            Assert.True(exitAsked);
+            var missing = new CompletionViewModel(Success("/does/not/exist"));
+            Assert.False(missing.CanOpenFolder);
+            Assert.False(missing.OpenFolderCommand.CanExecute(null));
         }
         finally
         {
-            File.Delete(launcher);
+            Directory.Delete(dir, recursive: true);
         }
     }
 }
diff --git a/Optimum.Installer/App.axaml b/Optimum.Installer/App.axaml
index 9c961c09..c97c4c5d 100644
--- a/Optimum.Installer/App.axaml
+++ b/Optimum.Installer/App.axaml
@@ -1,96 +1,29 @@
 <Application xmlns="https://github.com/avaloniaui"
              xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
-             xmlns:suki="https://github.com/kikipoulet/SukiUI"
+             xmlns:sty="using:FluentAvalonia.Styling"
              xmlns:local="using:Optimum.Installer"
              x:Class="Optimum.Installer.App"
              RequestedThemeVariant="Default">
-  <Application.Resources>
-    <ResourceDictionary>
-      <!-- Lexend for all UI text (SukiUI reads DefaultFontFamily throughout its
-           theme); JetBrains Mono inline for the log and command lines. -->
-      <FontFamily x:Key="DefaultFontFamily">avares://Optimum.Installer/Assets/Fonts/Lexend/Lexend-VF.ttf#Lexend</FontFamily>
-      <FontFamily x:Key="DisplayFont">avares://Optimum.Installer/Assets/Fonts/Lexend/Lexend-VF.ttf#Lexend</FontFamily>
-      <FontFamily x:Key="MonoFont">avares://Optimum.Installer/Assets/Fonts/JetBrainsMono/JetBrainsMono-VF.ttf#JetBrains Mono</FontFamily>
-
-      <!-- A faint tiled grain over the flat window background, so the surface
-           reads as a material rather than raw colour. Alpha is baked low (~5%);
-           it sits over both themes. -->
-      <ImageBrush x:Key="GrainBrush"
-                  Source="avares://Optimum.Installer/Assets/optimum-grain.png"
-                  TileMode="Tile" Stretch="None"
-                  DestinationRect="0,0,128,128" />
-
-      <!-- Cyan-slate surfaces, set explicitly so nothing is left to SukiUI's
-           primary-derived background (which skews green) or its neutral-grey
-           card fill. Everything leans blue (B > G) to stay cyan, not teal.
-             AppSurfaceBrush     - the window ground, under the grain
-             SukiGlassCardOpaque - every card and the rail (GlassCard IsOpaque)
-             InsetSurfaceBrush   - recessed panes (build notice, build log) -->
-      <ResourceDictionary.ThemeDictionaries>
-        <ResourceDictionary x:Key="Light">
-          <SolidColorBrush x:Key="AppSurfaceBrush" Color="#E8F0F2" />
-          <SolidColorBrush x:Key="InsetSurfaceBrush" Color="#DCE8EA" />
-          <SolidColorBrush x:Key="InsetBorderBrush" Color="#C3D5D8" />
-          <Color x:Key="SukiGlassCardOpaqueBackground">#F6FAFB</Color>
-        </ResourceDictionary>
-        <ResourceDictionary x:Key="Dark">
-          <SolidColorBrush x:Key="AppSurfaceBrush" Color="#102A31" />
-          <SolidColorBrush x:Key="InsetSurfaceBrush" Color="#0B2026" />
-          <SolidColorBrush x:Key="InsetBorderBrush" Color="#294D57" />
-          <Color x:Key="SukiGlassCardOpaqueBackground">#193B44</Color>
-        </ResourceDictionary>
-      </ResourceDictionary.ThemeDictionaries>
-    </ResourceDictionary>
-  </Application.Resources>
 
   <Application.DataTemplates>
     <local:ViewLocator />
   </Application.DataTemplates>
 
   <Application.Styles>
-    <!-- The colour theme is switched to the Optimum brand palette in App.axaml.cs. -->
-    <suki:SukiTheme />
-
-    <!-- Accessibility on top of the SukiUI scale: body up to 15/1.5, headings
-         a step larger, and secondary copy on a real 7:1 grey instead of
-         SukiUI's near-#8a8a8a caption colour. -->
-    <Style Selector="TextBlock">
-      <Setter Property="FontSize" Value="15" />
-      <Setter Property="LineHeight" Value="22" />
-    </Style>
-    <Style Selector="SelectableTextBlock">
-      <Setter Property="FontSize" Value="15" />
-      <Setter Property="LineHeight" Value="22" />
-    </Style>
-    <Style Selector="TextBlock.Caption">
-      <Setter Property="FontSize" Value="14" />
-      <Setter Property="Foreground" Value="{DynamicResource SukiLowText}" />
-    </Style>
-    <!-- Headings: own line height (the 22 above would clip Lexend's caps) and
-         no baked-in margin (SukiUI ships h2/h3/h4 with 12-20px of it). -->
-    <Style Selector="TextBlock.h5">
-      <Setter Property="FontSize" Value="17" />
-      <Setter Property="LineHeight" Value="24" />
-      <Setter Property="Margin" Value="0" />
-    </Style>
-    <Style Selector="TextBlock.h3">
-      <Setter Property="FontSize" Value="26" />
-      <Setter Property="LineHeight" Value="32" />
-      <Setter Property="Margin" Value="0" />
-    </Style>
-    <Style Selector="TextBlock.h2">
-      <Setter Property="FontSize" Value="29" />
-      <Setter Property="LineHeight" Value="36" />
-      <Setter Property="Margin" Value="0" />
-    </Style>
+    <!-- FluentAvalonia = the real WinUI 3 / Windows 11 look. It uses the OS
+         accent colour and the OS light/dark setting, and ships the full WinUI
+         resource brush set (TextFillColor*, CardBackgroundFillColor*,
+         SystemFillColor*, etc.). No custom palette. -->
+    <sty:FluentAvaloniaTheme PreferSystemTheme="True" PreferUserAccentColor="True" />
 
-    <!-- Tighter corners than SukiUI's 20px default (at 20 the rounding clips the
-         last line of text in a card whose padding is smaller than the radius),
-         and opaque (with the tinted fill above) so the window grain does not
-         bleed through the cards. -->
-    <Style Selector="suki|GlassCard">
-      <Setter Property="CornerRadius" Value="12" />
-      <Setter Property="IsOpaque" Value="True" />
+    <!-- The only shared helper: a standard WinUI "card" surface (a rounded
+         Border using the stock CardBackground/CardStroke tokens). -->
+    <Style Selector="Border.Card">
+      <Setter Property="Background" Value="{DynamicResource CardBackgroundFillColorDefaultBrush}" />
+      <Setter Property="BorderBrush" Value="{DynamicResource CardStrokeColorDefaultBrush}" />
+      <Setter Property="BorderThickness" Value="1" />
+      <Setter Property="CornerRadius" Value="8" />
+      <Setter Property="Padding" Value="16" />
     </Style>
   </Application.Styles>
 </Application>
diff --git a/Optimum.Installer/App.axaml.cs b/Optimum.Installer/App.axaml.cs
index c3182c02..03a13beb 100644
--- a/Optimum.Installer/App.axaml.cs
+++ b/Optimum.Installer/App.axaml.cs
@@ -1,12 +1,9 @@
 using Avalonia;
 using Avalonia.Controls.ApplicationLifetimes;
 using Avalonia.Markup.Xaml;
-using Avalonia.Media;
 using Optimum.Installer.Services;
 using Optimum.Installer.ViewModels;
 using Optimum.Installer.Views;
-using SukiUI;
-using SukiUI.Models;
 
 namespace Optimum.Installer;
 
@@ -16,14 +13,8 @@ public partial class App : Application
 
     public override void OnFrameworkInitializationCompleted()
     {
-        // Cyan throughout: a deep cyan primary (buttons, step markers, links,
-        // progress) and a brighter cyan accent. The window surfaces are set to
-        // matching cyan-slate tones in App.axaml so nothing reads green or grey.
-        SukiTheme.GetInstance().ChangeColorTheme(new SukiColorTheme(
-            "Optimum",
-            primary: Color.Parse("#0B7C97"),
-            accent: Color.Parse("#22A5C2")));
-
+        // Native Fluent theme; the OS supplies the accent colour and the
+        // light/dark variant. No runtime colour setup is needed.
         if (ApplicationLifetime is IClassicDesktopStyleApplicationLifetime desktop)
         {
             var shell = new MainWindowViewModel(InstallerServices.CreateReal());
diff --git a/Optimum.Installer/Optimum.Installer.csproj b/Optimum.Installer/Optimum.Installer.csproj
index 7ea5f598..ef69be69 100644
--- a/Optimum.Installer/Optimum.Installer.csproj
+++ b/Optimum.Installer/Optimum.Installer.csproj
@@ -12,6 +12,7 @@
     <AvaloniaUseCompiledBindingsByDefault>true</AvaloniaUseCompiledBindingsByDefault>
     <Description>Avalonia GUI for the Optimum installer. Links Optimum.Bootstrap.Core in-process.</Description>
     <Version>$(OptimumVersion)</Version>
+    <ApplicationIcon>..\Optimum.Launcher\optimum.ico</ApplicationIcon>
   </PropertyGroup>
   <ItemGroup>
     <!-- Bundled OFL 1.1 fonts: Lexend (all UI text), JetBrains Mono (log and
@@ -25,13 +26,11 @@
   <ItemGroup>
     <PackageReference Include="Avalonia" Version="12.1.1" />
     <PackageReference Include="Avalonia.Desktop" Version="12.1.1" />
-    <!-- SukiUI supplies the theme and controls (SukiWindow, VerticalStepper,
-         GlassCard, InfoBar, WaveProgress). It replaces Avalonia.Themes.Fluent
-         and pulls Avalonia.Themes.Simple + Skia + DataGrid + ColorPicker. -->
-    <PackageReference Include="SukiUI" Version="7.0.1" />
-    <!-- Avalonia.Diagnostics is not published for 12.x (nuget tops out at
-         11.3.20), so a Debug restore of this project fails with NU1102. The
-         dev-tools overlay is optional; drop it until a 12.x build ships. -->
+    <!-- FluentAvalonia brings the real WinUI 3 / Windows 11 look: the
+         FluentAvaloniaTheme, WinUI controls (NavigationView, ProgressRing,
+         FAComboBox), and the full WinUI resource brush set. 3.1.0 targets
+         Avalonia >= 12.1.0. -->
+    <PackageReference Include="FluentAvaloniaUI" Version="3.1.0" />
     <PackageReference Include="CommunityToolkit.Mvvm" Version="8.4.2" />
     <PackageReference Include="Velopack" Version="1.2.0" />
   </ItemGroup>
diff --git a/Optimum.Installer/Program.cs b/Optimum.Installer/Program.cs
index a90d8e30..adad7c38 100644
--- a/Optimum.Installer/Program.cs
+++ b/Optimum.Installer/Program.cs
@@ -23,7 +23,7 @@ public static AppBuilder BuildAvaloniaApp() =>
             .With(new FontManagerOptions
             {
                 // Lexend is also the app-wide default so any text outside a
-                // SukiUI template (tooltips, flyouts) matches.
+                // control template (tooltips, flyouts) matches.
                 DefaultFamilyName = "avares://Optimum.Installer/Assets/Fonts/Lexend/Lexend-VF.ttf#Lexend",
                 FontFallbacks = [new FontFallback { FontFamily = new FontFamily("Segoe UI") }],
             })
diff --git a/Optimum.Installer/ViewModels/CompletionViewModel.cs b/Optimum.Installer/ViewModels/CompletionViewModel.cs
index 923677d7..548393c6 100644
--- a/Optimum.Installer/ViewModels/CompletionViewModel.cs
+++ b/Optimum.Installer/ViewModels/CompletionViewModel.cs
@@ -1,5 +1,4 @@
 using System.Diagnostics;
-using CommunityToolkit.Mvvm.ComponentModel;
 using CommunityToolkit.Mvvm.Input;
 
 namespace Optimum.Installer.ViewModels;
@@ -22,13 +21,14 @@ public sealed partial class CompletionViewModel(InstallOutcome outcome) : ViewMo
 
     /// <summary>A line that adds to the headline rather than repeating it.</summary>
     public string Subtext => Outcome.Succeeded
-        ? "Launch it from the button below, or from your application menu."
+        ? "Launch Optimum from your application menu or the install folder."
         : Outcome.Message;
 
     public string Message => Outcome.Message;
     public string? InstallDirectory => Outcome.InstallDirectory;
 
-    public bool CanLaunch => Outcome.Launcher is not null && File.Exists(Outcome.Launcher);
+    /// <summary>Offer to open the install folder only when there is one to open.</summary>
+    public bool CanOpenFolder => Outcome.InstallDirectory is not null && Directory.Exists(Outcome.InstallDirectory);
 
     public bool HasLog => File.Exists(Outcome.RawLogPath);
 
@@ -37,96 +37,34 @@ public sealed partial class CompletionViewModel(InstallOutcome outcome) : ViewMo
 
     public event Action? RetryRequested;
 
-    /// <summary>Raised once the launched game has a window; the shell then exits.</summary>
+    /// <summary>Raised when the user finishes the wizard; the shell then exits.</summary>
     public event Action? ExitRequested;
 
-    /// <summary>True from the moment Launch is clicked until the shell closes.</summary>
-    [ObservableProperty]
-    [NotifyCanExecuteChangedFor(nameof(LaunchCommand))]
-    private bool _launching;
-
-    public string LaunchLabel => Launching ? "Launching Optimum..." : "Launch Optimum";
-
-    partial void OnLaunchingChanged(bool value) => OnPropertyChanged(nameof(LaunchLabel));
-
     [RelayCommand(CanExecute = nameof(CanRetry))]
     private void Retry() => RetryRequested?.Invoke();
 
-    private bool CanLaunchNow => CanLaunch && !Launching;
+    /// <summary>Close the installer. Standard "Finish" button on the final screen.</summary>
+    [RelayCommand]
+    private void Finish() => ExitRequested?.Invoke();
 
-    [RelayCommand(CanExecute = nameof(CanLaunchNow))]
-    private async Task Launch()
+    [RelayCommand(CanExecute = nameof(CanOpenFolder))]
+    private void OpenFolder()
     {
-        if (Outcome.Launcher is not { } launcher || Launching)
+        if (Outcome.InstallDirectory is not { } dir)
             return;
-
-        Launching = true;
         try
         {
-            // Run the launcher script directly. UseShellExecute would route a .sh
-            // through xdg-open on Linux, which opens it in an editor rather than
-            // running it.
+            // Open the install directory in the platform file manager.
             ProcessStartInfo start = OperatingSystem.IsWindows()
-                ? new ProcessStartInfo("cmd.exe", $"/c \"{launcher}\"") { UseShellExecute = false, CreateNoWindow = true }
-                : new ProcessStartInfo(launcher) { UseShellExecute = false };
-            start.WorkingDirectory = Path.GetDirectoryName(launcher) ?? Environment.CurrentDirectory;
+                ? new ProcessStartInfo("explorer.exe", $"\"{dir}\"")
+                : new ProcessStartInfo(dir) { UseShellExecute = true };
             Process.Start(start);
-
-            await WaitForGameWindowAsync();
         }
         catch (Exception)
         {
-            // Let the user try again rather than leaving a dead spinner.
-            Launching = false;
-            return;
-        }
-
-        ExitRequested?.Invoke();
-    }
-
-    /// <summary>
-    /// Holds the spinner until the launched game has put a window up. On Windows
-    /// this polls the Optimum process for a main window handle; elsewhere there
-    /// is no cheap window probe, so it waits a short fixed moment. Either way it
-    /// gives up after 45s and closes the installer anyway.
-    /// </summary>
-    private static async Task WaitForGameWindowAsync()
-    {
-        if (!OperatingSystem.IsWindows())
-        {
-            await Task.Delay(TimeSpan.FromSeconds(3));
-            return;
-        }
-
-        DateTime deadline = DateTime.UtcNow + TimeSpan.FromSeconds(45);
-        while (DateTime.UtcNow < deadline)
-        {
-            if (await Task.Run(() => HasVisibleWindow("Optimum") || HasVisibleWindow("Vintagestory")))
-                return;
-            await Task.Delay(400);
-        }
-    }
-
-    private static bool HasVisibleWindow(string processName)
-    {
-        foreach (Process process in Process.GetProcessesByName(processName))
-        {
-            try
-            {
-                process.Refresh();
-                if (process.MainWindowHandle != IntPtr.Zero)
-                    return true;
-            }
-            catch (Exception)
-            {
-                // Access denied / exited between the enumerate and the read.
-            }
-            finally
-            {
-                process.Dispose();
-            }
+            // Opening the folder is a convenience; ignore a failure rather than
+            // breaking the finish screen.
         }
-        return false;
     }
 
     [RelayCommand(CanExecute = nameof(HasLog))]
diff --git a/Optimum.Installer/ViewModels/InstallSession.cs b/Optimum.Installer/ViewModels/InstallSession.cs
index 1de2036b..b6c74aad 100644
--- a/Optimum.Installer/ViewModels/InstallSession.cs
+++ b/Optimum.Installer/ViewModels/InstallSession.cs
@@ -8,7 +8,8 @@ public sealed record InstallSession(
     string InstallDirectory,
     string? DataPath,
     string? Version,
-    ShortcutKinds Shortcuts);
+    ShortcutKinds Shortcuts,
+    bool CleanDestination = false);
 
 public sealed record InstallOutcome(
     bool Succeeded,
diff --git a/Optimum.Installer/ViewModels/MainWindowViewModel.cs b/Optimum.Installer/ViewModels/MainWindowViewModel.cs
index 9693e06e..a1678cb7 100644
--- a/Optimum.Installer/ViewModels/MainWindowViewModel.cs
+++ b/Optimum.Installer/ViewModels/MainWindowViewModel.cs
@@ -137,10 +137,10 @@ private async Task CheckForUpdateAsync(IUpdateService updates)
 
     private static readonly string[] StepNames = ["System", "Options", "Review", "Install"];
 
-    /// <summary>The rail labels for <c>suki:VerticalStepper</c>.</summary>
+    /// <summary>The rail labels for the step navigation.</summary>
     public IReadOnlyList<string> StepLabels => StepNames;
 
-    /// <summary>Zero-based current step for <c>suki:VerticalStepper.Index</c>.
+    /// <summary>Zero-based current step for the step rail.
     /// On a successful completion it points past the last step so the rail
     /// shows every step done rather than the last one still "current".</summary>
     public int StepIndex =>
@@ -201,7 +201,7 @@ public IReadOnlyList<WizardStep> Steps
         WizardScreen.Options => "Where Optimum goes, the game data it uses, and the shortcuts to add.",
         WizardScreen.Review => "Confirm the summary, then read and accept the build notice.",
         WizardScreen.Progress => "This runs on your computer and can take a few minutes the first time.",
-        WizardScreen.Completion when Completion?.Succeeded == true => "Optimum is ready to launch.",
+        WizardScreen.Completion when Completion?.Succeeded == true => "Optimum is installed and ready to play.",
         WizardScreen.Completion => "Nothing on your system was changed. Fix the issue below, then try again.",
         _ => string.Empty,
     };
@@ -277,7 +277,8 @@ private async Task StartInstallAsync()
             Options.ResolvedDataPath,
             Options.SelectedVersion,
             (Options.CreateMenuEntry ? ShortcutKinds.Menu : ShortcutKinds.None)
-                | (Options.CreateDesktopShortcut ? ShortcutKinds.Desktop : ShortcutKinds.None));
+                | (Options.CreateDesktopShortcut ? ShortcutKinds.Desktop : ShortcutKinds.None),
+            Options.CleanInstallDirectory);
 
         var progress = new ProgressViewModel(_services, session, _services.UiPost);
         progress.Finished += OnBuildFinished;
diff --git a/Optimum.Installer/ViewModels/OptionsViewModel.cs b/Optimum.Installer/ViewModels/OptionsViewModel.cs
index 29220f10..c9195c7c 100644
--- a/Optimum.Installer/ViewModels/OptionsViewModel.cs
+++ b/Optimum.Installer/ViewModels/OptionsViewModel.cs
@@ -70,6 +70,9 @@ public OptionsViewModel(ISystemProbe probe, string? repoRoot)
     [ObservableProperty]
     private bool _createDesktopShortcut;
 
+    [ObservableProperty]
+    private bool _cleanInstallDirectory = true;
+
     [ObservableProperty]
     [NotifyPropertyChangedFor(nameof(CanContinue))]
     private string? _validationError;
@@ -92,6 +95,8 @@ private void Continue()
 
     partial void OnInstallDirectoryChanged(string value) => Validate();
 
+    partial void OnCleanInstallDirectoryChanged(bool value) => Validate();
+
     partial void OnUseSeparateDataFolderChanged(bool value) => Validate();
 
     partial void OnDataPathChanged(string value) => Validate();
@@ -105,7 +110,8 @@ public void Validate()
         }
 
         string? data = UseSeparateDataFolder && DataPath.Length > 0 ? DataPath : null;
-        InstallPathVerdict verdict = InstallPathGuard.Check(_probe, new InstallPathRequest(InstallDirectory, data));
+        InstallPathVerdict verdict = InstallPathGuard.Check(_probe, new InstallPathRequest(
+            InstallDirectory, data, CleanDestination: CleanInstallDirectory));
         ValidationError = verdict.Ok ? null : verdict.Rejection;
     }
 
diff --git a/Optimum.Installer/ViewModels/ProgressViewModel.cs b/Optimum.Installer/ViewModels/ProgressViewModel.cs
index 8a6b3328..ab2c237b 100644
--- a/Optimum.Installer/ViewModels/ProgressViewModel.cs
+++ b/Optimum.Installer/ViewModels/ProgressViewModel.cs
@@ -143,7 +143,7 @@ private async Task<InstallOutcome> RunBuildAndDeployAsync(string outputDirectory
 
         Phase(ProgressPhase.Verify, 96, "installing");
         DeployResult deploy = _services.Installer.Deploy(
-            new DeployRequest(build.RuntimePath!, _session.InstallDirectory, _session.DataPath, _session.Shortcuts),
+            new DeployRequest(build.RuntimePath!, _session.InstallDirectory, _session.DataPath, _session.Shortcuts, _session.CleanDestination),
             this);
 
         if (!deploy.Ok)
diff --git a/Optimum.Installer/Views/CompletionView.axaml b/Optimum.Installer/Views/CompletionView.axaml
index 66b132b9..92af8d80 100644
--- a/Optimum.Installer/Views/CompletionView.axaml
+++ b/Optimum.Installer/Views/CompletionView.axaml
@@ -1,6 +1,5 @@
 <UserControl xmlns="https://github.com/avaloniaui"
              xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
-             xmlns:suki="https://github.com/kikipoulet/SukiUI"
              xmlns:vm="using:Optimum.Installer.ViewModels"
              xmlns:conv="using:Optimum.Installer.Views"
              x:Class="Optimum.Installer.Views.CompletionView"
@@ -11,28 +10,30 @@
       <Border Width="44" Height="44" CornerRadius="22" VerticalAlignment="Center"
               Background="{Binding Succeeded, Converter={x:Static conv:InstallerConverters.OutcomeBrush}}">
         <TextBlock Text="{Binding Succeeded, Converter={x:Static conv:InstallerConverters.OutcomeGlyph}}"
-                   FontSize="22" FontWeight="Bold" Foreground="White"
+                   FontSize="22" FontWeight="Bold"
+                   Foreground="{DynamicResource TextOnAccentFillColorPrimaryBrush}"
                    HorizontalAlignment="Center" VerticalAlignment="Center" />
       </Border>
-      <TextBlock Text="{Binding Headline}" Classes="h2" VerticalAlignment="Center" />
+      <TextBlock Text="{Binding Headline}" FontSize="28" FontWeight="SemiBold" VerticalAlignment="Center" />
     </StackPanel>
 
     <TextBlock Text="{Binding Subtext}" TextWrapping="Wrap" MaxWidth="620" />
 
-    <suki:GlassCard IsVisible="{Binding InstallDirectory, Converter={x:Static StringConverters.IsNotNullOrEmpty}}">
+    <Border Classes="Card" IsVisible="{Binding InstallDirectory, Converter={x:Static StringConverters.IsNotNullOrEmpty}}">
       <StackPanel Spacing="4">
-        <TextBlock Text="Installed at" Classes="Caption" />
-        <SelectableTextBlock Text="{Binding InstallDirectory}" FontWeight="DemiBold" TextWrapping="Wrap"
-                             FontFamily="{DynamicResource MonoFont}" />
+        <TextBlock Text="Installed at" Foreground="{DynamicResource TextFillColorSecondaryBrush}" />
+        <SelectableTextBlock Text="{Binding InstallDirectory}" FontWeight="SemiBold" TextWrapping="Wrap"
+                             FontFamily="Cascadia Code, Consolas, monospace" />
       </StackPanel>
-    </suki:GlassCard>
+    </Border>
 
     <StackPanel Orientation="Horizontal" Spacing="10" Margin="0,6,0,0">
-      <Button Content="{Binding LaunchLabel}" Classes="Flat"
+      <Button Content="Finish" Classes="accent"
               IsVisible="{Binding Succeeded}"
-              suki:ButtonExtensions.ShowProgress="{Binding Launching}"
-              Command="{Binding LaunchCommand}" />
-      <Button Content="Try again" Classes="Flat"
+              Command="{Binding FinishCommand}" />
+      <Button Content="Open install folder"
+              IsVisible="{Binding CanOpenFolder}" Command="{Binding OpenFolderCommand}" />
+      <Button Content="Try again" Classes="accent"
               IsVisible="{Binding CanRetry}" Command="{Binding RetryCommand}" />
       <Button Content="Open log"
               IsVisible="{Binding ShowLog}" Command="{Binding ViewLogCommand}" />
diff --git a/Optimum.Installer/Views/EulaView.axaml b/Optimum.Installer/Views/EulaView.axaml
index cc52fc11..6cbaf7a0 100644
--- a/Optimum.Installer/Views/EulaView.axaml
+++ b/Optimum.Installer/Views/EulaView.axaml
@@ -1,61 +1,61 @@
 <UserControl xmlns="https://github.com/avaloniaui"
              xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
-             xmlns:suki="https://github.com/kikipoulet/SukiUI"
              xmlns:vm="using:Optimum.Installer.ViewModels"
              x:Class="Optimum.Installer.Views.EulaView"
              x:DataType="vm:EulaViewModel">
   <Grid RowDefinitions="Auto,*,Auto">
 
-    <suki:GlassCard Grid.Row="0" Margin="0,0,0,12">
+    <Border Classes="Card" Grid.Row="0" Margin="0,0,0,12">
       <StackPanel Spacing="10">
-        <TextBlock Text="Summary" Classes="h5" />
+        <TextBlock Text="Summary" FontSize="17" FontWeight="SemiBold" />
         <Grid ColumnDefinitions="*,*" RowDefinitions="Auto,Auto">
           <StackPanel Grid.Row="0" Grid.Column="0" Spacing="2" Margin="0,0,16,12">
-            <TextBlock Text="Install to" Classes="Caption" />
-            <TextBlock Text="{Binding InstallDirectory}" TextWrapping="Wrap" FontWeight="DemiBold" />
+            <TextBlock Text="Install to" Foreground="{DynamicResource TextFillColorSecondaryBrush}" />
+            <TextBlock Text="{Binding InstallDirectory}" TextWrapping="Wrap" FontWeight="SemiBold" />
           </StackPanel>
           <StackPanel Grid.Row="0" Grid.Column="1" Spacing="2" Margin="0,0,0,12">
-            <TextBlock Text="Game data" Classes="Caption" />
-            <TextBlock Text="{Binding DataPathSummary}" TextWrapping="Wrap" FontWeight="DemiBold" />
+            <TextBlock Text="Game data" Foreground="{DynamicResource TextFillColorSecondaryBrush}" />
+            <TextBlock Text="{Binding DataPathSummary}" TextWrapping="Wrap" FontWeight="SemiBold" />
           </StackPanel>
           <StackPanel Grid.Row="1" Grid.Column="0" Spacing="2" Margin="0,0,16,0">
-            <TextBlock Text="Version" Classes="Caption" />
-            <TextBlock Text="{Binding VersionSummary}" FontWeight="DemiBold" />
+            <TextBlock Text="Version" Foreground="{DynamicResource TextFillColorSecondaryBrush}" />
+            <TextBlock Text="{Binding VersionSummary}" FontWeight="SemiBold" />
           </StackPanel>
           <StackPanel Grid.Row="1" Grid.Column="1" Spacing="2">
-            <TextBlock Text="Shortcuts" Classes="Caption" />
-            <TextBlock Text="{Binding ShortcutSummary}" TextWrapping="Wrap" FontWeight="DemiBold" />
+            <TextBlock Text="Shortcuts" Foreground="{DynamicResource TextFillColorSecondaryBrush}" />
+            <TextBlock Text="{Binding ShortcutSummary}" TextWrapping="Wrap" FontWeight="SemiBold" />
           </StackPanel>
         </Grid>
       </StackPanel>
-    </suki:GlassCard>
+    </Border>
 
-    <suki:GlassCard Grid.Row="1" Padding="0">
+    <Border Classes="Card" Grid.Row="1" Padding="0">
       <Grid RowDefinitions="Auto,Auto,*">
-        <TextBlock Grid.Row="0" Text="Build notice" Classes="h5" Margin="16,14,16,0" />
+        <TextBlock Grid.Row="0" Text="Build notice" FontSize="17" FontWeight="SemiBold" Margin="16,14,16,0" />
         <TextBlock Grid.Row="1" Margin="16,4,16,10"
                    Text="Optimum is compiled from your own Vintage Story installation. Read to the end to continue."
-                   Classes="Caption" TextWrapping="Wrap" />
-        <Border Grid.Row="2" Background="{DynamicResource InsetSurfaceBrush}"
-                BorderBrush="{DynamicResource InsetBorderBrush}" BorderThickness="0,1,0,0"
-                CornerRadius="0,0,12,12">
+                   Foreground="{DynamicResource TextFillColorSecondaryBrush}" TextWrapping="Wrap" />
+        <Border Grid.Row="2" Background="{DynamicResource LayerFillColorDefaultBrush}"
+                BorderBrush="{DynamicResource CardStrokeColorDefaultBrush}" BorderThickness="0,1,0,0"
+                CornerRadius="0,0,8,8">
           <ScrollViewer x:Name="Scroller" ScrollChanged="OnScrollChanged" Padding="16,12"
                         AutomationProperties.Name="Optimum build notice">
             <TextBlock Text="{Binding ConsentText}" TextWrapping="Wrap" />
           </ScrollViewer>
         </Border>
       </Grid>
-    </suki:GlassCard>
+    </Border>
 
     <StackPanel Grid.Row="2" Spacing="10" Margin="0,12,0,0">
       <CheckBox Content="I have read and accept this notice"
                 IsChecked="{Binding Accepted}" x:Name="AcceptBox" TabIndex="1" />
       <Grid ColumnDefinitions="*,Auto,Auto">
-        <TextBlock Grid.Column="0" Text="{Binding ScrollHint}" Classes="Caption"
+        <TextBlock Grid.Column="0" Text="{Binding ScrollHint}"
+                   Foreground="{DynamicResource TextFillColorSecondaryBrush}"
                    VerticalAlignment="Center" AutomationProperties.LiveSetting="Polite" />
         <Button Grid.Column="1" Content="Back" Margin="8,0,0,0"
                 Command="{Binding DeclineCommand}" TabIndex="2" />
-        <Button Grid.Column="2" Content="Start install" Classes="Flat" Margin="8,0,0,0"
+        <Button Grid.Column="2" Content="Start install" Classes="accent" Margin="8,0,0,0"
                 IsEnabled="{Binding CanAccept}" Command="{Binding AcceptCommand}" TabIndex="3" />
       </Grid>
     </StackPanel>
diff --git a/Optimum.Installer/Views/InstallerConverters.cs b/Optimum.Installer/Views/InstallerConverters.cs
index 7a344694..7f6e33ca 100644
--- a/Optimum.Installer/Views/InstallerConverters.cs
+++ b/Optimum.Installer/Views/InstallerConverters.cs
@@ -2,53 +2,66 @@
 using Avalonia.Controls.Notifications;
 using Avalonia.Data.Converters;
 using Avalonia.Media;
+using Avalonia.Styling;
 
 namespace Optimum.Installer.Views;
 
-/// <summary>Small view-only converters, resolved against SukiUI's theme resources.</summary>
+/// <summary>Small view-only converters, resolved against the native Avalonia
+/// Fluent theme resources (WinUI-style tokens). No custom palette.</summary>
 public static class InstallerConverters
 {
-    /// <summary>Prerequisite status label colour: optional → info blue, blocker → warning.</summary>
+    /// <summary>Prerequisite status label colour: optional → accent, blocker → caution.</summary>
     public static readonly IValueConverter StatusBrush =
         new FuncValueConverter<bool, IBrush?>(isOptional =>
-            Brush(isOptional ? "SukiInformationColor" : "SukiWarningColor"));
+            Brush(isOptional ? "SystemAccentColorLight1" : "SystemFillColorCautionBrush"));
 
-    /// <summary>Install outcome → the completion info bar severity.</summary>
+    /// <summary>Install outcome → the completion banner severity.</summary>
     public static readonly IValueConverter OutcomeSeverity =
         new FuncValueConverter<bool, NotificationType>(ok =>
             ok ? NotificationType.Success : NotificationType.Error);
 
-    /// <summary>Install outcome → the colour of the completion badge. A pass is
-    /// the cyan primary (the installer runs on cyan, not green); a failure is red.</summary>
+    /// <summary>Install outcome → the colour of the completion badge: a success
+    /// green on pass, the critical red on failure (standard Fluent status colours).</summary>
     public static readonly IValueConverter OutcomeBrush =
         new FuncValueConverter<bool, IBrush?>(ok =>
-            Brush(ok ? "SukiPrimaryColor" : "SukiDangerColor"));
+            Brush(ok ? "SystemFillColorSuccessBrush" : "SystemFillColorCriticalBrush"));
 
     /// <summary>Install outcome → the badge glyph.</summary>
     public static readonly IValueConverter OutcomeGlyph =
         new FuncValueConverter<bool, string>(ok => ok ? "✓" : "!");
 
-    /// <summary>A reached step's circle is filled with the accent; a pending one is hollow.</summary>
+    /// <summary>A reached step's circle is filled with the system accent; a pending one is hollow.</summary>
     public static readonly IValueConverter StepCircleBrush =
         new FuncValueConverter<bool, IBrush?>(reached =>
-            reached ? Brush("SukiPrimaryColor") : new SolidColorBrush(Colors.Transparent));
+            reached ? Brush("SystemAccentColor") : new SolidColorBrush(Colors.Transparent));
 
     /// <summary>A pending step's circle has a 1.5px outline; a reached one has none.</summary>
     public static readonly IValueConverter StepCircleBorder =
         new FuncValueConverter<bool, Thickness>(reached => new Thickness(reached ? 0 : 1.5));
 
-    /// <summary>Reached step labels are full strength; pending ones are muted.</summary>
+    /// <summary>Reached step labels are full strength; pending ones are muted.
+    /// Explicit theme-aware colours so they always render (the WinUI text brushes
+    /// are not resolvable through Application.TryGetResource).</summary>
     public static readonly IValueConverter StepLabelBrush =
         new FuncValueConverter<bool, IBrush?>(reached =>
-            Brush(reached ? "SukiText" : "SukiLowText"));
+        {
+            bool dark = Application.Current?.ActualThemeVariant == ThemeVariant.Dark;
+            if (reached)
+                return new SolidColorBrush(dark ? Color.FromRgb(0xFF, 0xFF, 0xFF) : Color.FromRgb(0x1A, 0x1A, 0x1A));
+            return new SolidColorBrush(dark ? Color.FromArgb(0x9E, 0xFF, 0xFF, 0xFF) : Color.FromArgb(0x9E, 0x00, 0x00, 0x00));
+        });
+
+    /// <summary>The current step's label is emphasised; others are regular weight.</summary>
+    public static readonly IValueConverter StepWeight =
+        new FuncValueConverter<bool, FontWeight>(current => current ? FontWeight.SemiBold : FontWeight.Normal);
 
     /// <summary>Log line level ("error"/"warn"/other) → its colour.</summary>
     public static readonly IValueConverter LogLevelBrush =
         new FuncValueConverter<string, IBrush?>(level => Brush(level switch
         {
-            "error" => "SukiDangerColor",
-            "warn" => "SukiWarningColor",
-            _ => "SukiLowText",
+            "error" => "SystemFillColorCriticalBrush",
+            "warn" => "SystemFillColorCautionBrush",
+            _ => "TextFillColorSecondaryBrush",
         }));
 
     private static IBrush? Brush(string key)
diff --git a/Optimum.Installer/Views/MainWindow.axaml b/Optimum.Installer/Views/MainWindow.axaml
index 8b4a08a8..a6672c8f 100644
--- a/Optimum.Installer/Views/MainWindow.axaml
+++ b/Optimum.Installer/Views/MainWindow.axaml
@@ -1,99 +1,94 @@
-<suki:SukiWindow xmlns="https://github.com/avaloniaui"
-                 xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
-                 xmlns:suki="https://github.com/kikipoulet/SukiUI"
-                 xmlns:vm="using:Optimum.Installer.ViewModels"
-                 xmlns:views="using:Optimum.Installer.Views"
-                 x:Class="Optimum.Installer.Views.MainWindow"
-                 x:DataType="vm:MainWindowViewModel"
-                 Width="960" Height="800"
-                 MinWidth="880" MinHeight="740"
-                 WindowStartupLocation="CenterScreen"
-                 CanFullScreen="False"
-                 BackgroundStyle="Flat"
-                 BackgroundAnimationEnabled="False"
-                 Icon="avares://Optimum.Installer/Assets/optimum-logo.png"
-                 Title="{Binding Title}">
+<Window xmlns="https://github.com/avaloniaui"
+        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+        xmlns:vm="using:Optimum.Installer.ViewModels"
+        xmlns:views="using:Optimum.Installer.Views"
+        x:Class="Optimum.Installer.Views.MainWindow"
+        x:DataType="vm:MainWindowViewModel"
+        Width="960" Height="800"
+        MinWidth="880" MinHeight="740"
+        WindowStartupLocation="CenterScreen"
+        Icon="avares://Optimum.Installer/Assets/optimum-logo.png"
+        Title="{Binding Title}">
 
-  <suki:SukiWindow.LogoContent>
-    <Image Source="avares://Optimum.Installer/Assets/optimum-logo.png"
-           Width="22" Height="22" VerticalAlignment="Center" />
-  </suki:SukiWindow.LogoContent>
+  <Grid ColumnDefinitions="200,*">
 
-  <!-- Opaque cyan-slate ground: covers SukiUI's primary-derived shader
-       background (which skews green) with a flat surface, then the grain. -->
-  <Panel Background="{DynamicResource AppSurfaceBrush}">
-    <Border Background="{StaticResource GrainBrush}" IsHitTestVisible="False" />
-
-    <Grid ColumnDefinitions="188,*">
-
-    <suki:GlassCard Grid.Column="0" Margin="10" CornerRadius="12" Padding="16,22">
-      <!-- A plain, static rail: SukiUI's VerticalStepper reflows the label of
-           the active step (it reveals a description slot), which makes the text
-           jump on every step change. Each row is a fixed width and the list is
-           centred, so the gap left of the circle matches the gap right of the
-           label. -->
-      <ItemsControl ItemsSource="{Binding Steps}" VerticalAlignment="Top"
-                    HorizontalAlignment="Center">
+    <!-- Step rail: a standard navigation column tinted with the Fluent layer
+         brush. Each row shows a numbered marker and its label; the marker fills
+         with the system accent once the step is reached, and a check replaces
+         the number once it is done. Foregrounds bind through the visual tree
+         (DynamicResource) so they resolve against the live Fluent theme. -->
+    <Border Grid.Column="0" Background="{DynamicResource SolidBackgroundFillColorSecondaryBrush}"
+            BorderBrush="{DynamicResource CardStrokeColorDefaultBrush}" BorderThickness="0,0,1,0">
+      <ItemsControl ItemsSource="{Binding Steps}" VerticalAlignment="Top" Margin="20,28">
         <ItemsControl.ItemTemplate>
           <DataTemplate x:DataType="vm:WizardStep">
-            <Grid ColumnDefinitions="28,Auto" Height="48" Width="104">
-              <Border Grid.Column="0" Width="28" Height="28" CornerRadius="14" VerticalAlignment="Center"
+            <Grid ColumnDefinitions="32,*" Height="48" Margin="0,2">
+              <!-- Marker: filled accent when reached, hollow outline when upcoming. -->
+              <Border Grid.Column="0" Width="30" Height="30" CornerRadius="15" VerticalAlignment="Center"
                       Background="{Binding IsReached, Converter={x:Static views:InstallerConverters.StepCircleBrush}}"
-                      BorderBrush="{DynamicResource SukiControlBorderBrush}"
+                      BorderBrush="{DynamicResource ControlStrongStrokeColorDefaultBrush}"
                       BorderThickness="{Binding IsReached, Converter={x:Static views:InstallerConverters.StepCircleBorder}}">
                 <Panel>
                   <TextBlock Text="{Binding Number}" FontSize="13" FontWeight="SemiBold"
                              HorizontalAlignment="Center" VerticalAlignment="Center"
-                             Foreground="{Binding IsReached, Converter={x:Static views:InstallerConverters.StepLabelBrush}}"
-                             IsVisible="{Binding !IsDone}" />
+                             Foreground="{DynamicResource TextOnAccentFillColorPrimaryBrush}"
+                             IsVisible="{Binding IsCurrent}" />
+                  <TextBlock Text="{Binding Number}" FontSize="13" FontWeight="SemiBold"
+                             HorizontalAlignment="Center" VerticalAlignment="Center"
+                             Foreground="{DynamicResource TextFillColorSecondaryBrush}"
+                             IsVisible="{Binding !IsReached}" />
                   <PathIcon Data="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"
-                            Width="12" Height="12" Foreground="White"
+                            Width="13" Height="13"
+                            Foreground="{DynamicResource TextOnAccentFillColorPrimaryBrush}"
                             HorizontalAlignment="Center" VerticalAlignment="Center"
                             IsVisible="{Binding IsDone}" />
                 </Panel>
               </Border>
-              <TextBlock Grid.Column="1" Text="{Binding Name}" VerticalAlignment="Center" Margin="12,0,0,0"
-                         FontSize="15" FontWeight="SemiBold"
+              <TextBlock Grid.Column="1" Text="{Binding Name}" VerticalAlignment="Center" Margin="14,0,0,0"
+                         FontSize="14" TextWrapping="Wrap"
+                         FontWeight="{Binding IsCurrent, Converter={x:Static views:InstallerConverters.StepWeight}}"
                          Foreground="{Binding IsReached, Converter={x:Static views:InstallerConverters.StepLabelBrush}}" />
             </Grid>
           </DataTemplate>
         </ItemsControl.ItemTemplate>
       </ItemsControl>
-    </suki:GlassCard>
+    </Border>
 
     <Grid Grid.Column="1" RowDefinitions="Auto,Auto,*" Margin="28,20,28,20">
       <StackPanel Grid.Row="0" Spacing="2" IsVisible="{Binding HeaderVisible}">
-        <TextBlock Text="{Binding CurrentStepLabel}" Classes="Primary" FontWeight="DemiBold"
-                   FontSize="13" LetterSpacing="1.5" />
-        <TextBlock Text="{Binding CurrentStepTitle}" Classes="h2"
-                   FontFamily="{DynamicResource DisplayFont}" />
-        <TextBlock Text="{Binding CurrentStepDescription}" Classes="Caption"
+        <TextBlock Text="{Binding CurrentStepLabel}" FontWeight="SemiBold"
+                   FontSize="13"
+                   Foreground="{DynamicResource SystemAccentColorLight1}" />
+        <TextBlock Text="{Binding CurrentStepTitle}" FontSize="28" FontWeight="SemiBold" />
+        <TextBlock Text="{Binding CurrentStepDescription}"
+                   Foreground="{DynamicResource TextFillColorSecondaryBrush}"
                    TextWrapping="Wrap" MaxWidth="620" HorizontalAlignment="Left" />
       </StackPanel>
 
-      <suki:GlassCard Grid.Row="1" Margin="0,14,0,0" IsVisible="{Binding UpdatePromptVisible}">
+      <Border Grid.Row="1" Classes="Card" Margin="0,14,0,0" IsVisible="{Binding UpdatePromptVisible}">
         <StackPanel DataContext="{Binding UpdateBanner}" Spacing="10">
           <Grid ColumnDefinitions="*,Auto,Auto">
-            <TextBlock Grid.Column="0" Text="{Binding Message}" Classes="Warning"
-                       VerticalAlignment="Center" TextWrapping="Wrap" FontWeight="DemiBold" />
-            <Button Grid.Column="1" Content="Update now" Classes="Flat" Margin="10,0,0,0"
+            <TextBlock Grid.Column="0" Text="{Binding Message}"
+                       Foreground="{DynamicResource SystemFillColorCautionBrush}"
+                       VerticalAlignment="Center" TextWrapping="Wrap" FontWeight="SemiBold" />
+            <Button Grid.Column="1" Content="Update now" Classes="accent" Margin="10,0,0,0"
                     IsEnabled="{Binding !Updating}" Command="{Binding UpdateCommand}" />
             <Button Grid.Column="2" Content="Later" Margin="8,0,0,0"
                     IsEnabled="{Binding !Updating}" Command="{Binding DismissCommand}" />
           </Grid>
           <ProgressBar Minimum="0" Maximum="100" Value="{Binding Progress}" IsVisible="{Binding Updating}" />
-          <TextBlock Text="{Binding Error}" Classes="Danger" TextWrapping="Wrap"
+          <TextBlock Text="{Binding Error}"
+                     Foreground="{DynamicResource SystemFillColorCriticalBrush}" TextWrapping="Wrap"
                      IsVisible="{Binding Error, Converter={x:Static StringConverters.IsNotNullOrEmpty}}" />
         </StackPanel>
-      </suki:GlassCard>
+      </Border>
 
-      <!-- Skip the fade entirely when the OS asks for reduced motion. -->
-      <suki:SukiTransitioningContentControl Grid.Row="2" Content="{Binding CurrentViewModel}"
-                                            Margin="0,12,0,0"
-                                            IsVisible="{x:Static views:MotionSettings.AllowMotion}" />
+      <!-- Fade between steps, unless the OS asks for reduced motion. -->
+      <TransitioningContentControl Grid.Row="2" Content="{Binding CurrentViewModel}"
+                                   Margin="0,12,0,0"
+                                   IsVisible="{x:Static views:MotionSettings.AllowMotion}" />
       <ContentControl Grid.Row="2" Content="{Binding CurrentViewModel}" Margin="0,12,0,0"
                       IsVisible="{x:Static views:MotionSettings.ReduceMotion}" />
     </Grid>
-    </Grid>
-  </Panel>
-</suki:SukiWindow>
+  </Grid>
+</Window>
diff --git a/Optimum.Installer/Views/MainWindow.axaml.cs b/Optimum.Installer/Views/MainWindow.axaml.cs
index 3ecf9dd7..0503eaf4 100644
--- a/Optimum.Installer/Views/MainWindow.axaml.cs
+++ b/Optimum.Installer/Views/MainWindow.axaml.cs
@@ -1,8 +1,9 @@
-using SukiUI.Controls;
+using Avalonia.Controls;
+using Avalonia.Markup.Xaml;
 
 namespace Optimum.Installer.Views;
 
-public partial class MainWindow : SukiWindow
+public partial class MainWindow : Window
 {
     public MainWindow() => InitializeComponent();
 }
diff --git a/Optimum.Installer/Views/OptionsView.axaml b/Optimum.Installer/Views/OptionsView.axaml
index 3cd22ae2..d70c16dc 100644
--- a/Optimum.Installer/Views/OptionsView.axaml
+++ b/Optimum.Installer/Views/OptionsView.axaml
@@ -1,6 +1,5 @@
 <UserControl xmlns="https://github.com/avaloniaui"
              xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
-             xmlns:suki="https://github.com/kikipoulet/SukiUI"
              xmlns:vm="using:Optimum.Installer.ViewModels"
              x:Class="Optimum.Installer.Views.OptionsView"
              x:DataType="vm:OptionsViewModel">
@@ -8,51 +7,57 @@
     <ScrollViewer Grid.Row="0" HorizontalScrollBarVisibility="Disabled">
       <StackPanel Spacing="8">
 
-        <suki:GlassCard Padding="16">
+        <Border Classes="Card">
           <StackPanel Spacing="8">
-            <TextBlock Text="Install location" Classes="h5" />
+            <TextBlock Text="Install location" FontSize="17" FontWeight="SemiBold" />
             <StackPanel Spacing="6">
-              <TextBlock Text="Install folder path" Classes="Caption" FontWeight="DemiBold" />
+              <TextBlock Text="Install folder path"
+                         Foreground="{DynamicResource TextFillColorSecondaryBrush}" FontWeight="SemiBold" />
               <Grid ColumnDefinitions="*,Auto">
                 <TextBox Grid.Column="0" Text="{Binding InstallDirectory}" PlaceholderText="Install directory"
                          AutomationProperties.Name="Install directory" TabIndex="1" />
                 <Button Grid.Column="1" Content="Browse" Margin="8,0,0,0" Click="BrowseInstallDirectory"
                         AutomationProperties.Name="Browse for an install directory" />
               </Grid>
-              <TextBlock Text="An empty folder you own. Optimum is built in a temporary workspace and moved here when it is ready."
-                         Classes="Caption" TextWrapping="Wrap" />
-              <TextBlock Text="{Binding ValidationError}" Classes="Danger" FontWeight="DemiBold"
+              <TextBlock Text="Optimum is built in a temporary workspace and moved here only after build and verification succeed."
+                         Foreground="{DynamicResource TextFillColorSecondaryBrush}" TextWrapping="Wrap" />
+              <CheckBox Content="Clean install folder if not empty"
+                        IsChecked="{Binding CleanInstallDirectory}" TabIndex="2" />
+              <TextBlock Text="{Binding ValidationError}" FontWeight="SemiBold"
+                         Foreground="{DynamicResource SystemFillColorCriticalBrush}"
                          TextWrapping="Wrap" AutomationProperties.LiveSetting="Assertive"
                          IsVisible="{Binding ValidationError, Converter={x:Static StringConverters.IsNotNullOrEmpty}}" />
             </StackPanel>
           </StackPanel>
-        </suki:GlassCard>
+        </Border>
 
-        <suki:GlassCard Padding="16">
+        <Border Classes="Card">
           <StackPanel Spacing="8">
-            <TextBlock Text="Game data" Classes="h5" />
+            <TextBlock Text="Game data" FontSize="17" FontWeight="SemiBold" />
             <CheckBox Content="Use a separate Vintage Story data folder"
                       IsChecked="{Binding UseSeparateDataFolder}" TabIndex="2" />
             <TextBlock Text="Off: Optimum shares Vintage Story's settings, worlds, and signed-in session. On: it keeps its own."
-                       Classes="Caption" TextWrapping="Wrap" />
+                       Foreground="{DynamicResource TextFillColorSecondaryBrush}" TextWrapping="Wrap" />
             <StackPanel Spacing="6" IsVisible="{Binding UseSeparateDataFolder}">
-              <TextBlock Text="Data folder path" Classes="Caption" FontWeight="DemiBold" />
+              <TextBlock Text="Data folder path"
+                         Foreground="{DynamicResource TextFillColorSecondaryBrush}" FontWeight="SemiBold" />
               <Grid ColumnDefinitions="*,Auto">
                 <TextBox Grid.Column="0" Text="{Binding DataPath}" PlaceholderText="Vintage Story data folder"
                          AutomationProperties.Name="Vintage Story data folder" TabIndex="3" />
                 <Button Grid.Column="1" Content="Browse" Margin="8,0,0,0" Click="BrowseDataPath"
                         AutomationProperties.Name="Browse for a Vintage Story data folder" />
               </Grid>
-              <TextBlock Text="{Binding DataPathHint}" Classes="Caption" TextWrapping="Wrap"
+              <TextBlock Text="{Binding DataPathHint}"
+                         Foreground="{DynamicResource TextFillColorSecondaryBrush}" TextWrapping="Wrap"
                          IsVisible="{Binding DataPathHint, Converter={x:Static StringConverters.IsNotNullOrEmpty}}" />
             </StackPanel>
           </StackPanel>
-        </suki:GlassCard>
+        </Border>
 
-        <suki:GlassCard Padding="16">
+        <Border Classes="Card">
           <Grid ColumnDefinitions="*,Auto">
             <StackPanel Grid.Column="0" Spacing="8">
-              <TextBlock Text="Shortcuts" Classes="h5" />
+              <TextBlock Text="Shortcuts" FontSize="17" FontWeight="SemiBold" />
               <CheckBox Content="Add an application menu entry"
                         IsChecked="{Binding CreateMenuEntry}" TabIndex="4" />
               <CheckBox Content="Create a desktop shortcut"
@@ -60,22 +65,22 @@
             </StackPanel>
             <StackPanel Grid.Column="1" Spacing="7" Width="250" Margin="20,0,0,0"
                         IsVisible="{Binding ShowVersionChoice}">
-              <TextBlock Text="Vintage Story version" Classes="h5" />
+              <TextBlock Text="Vintage Story version" FontSize="17" FontWeight="SemiBold" />
               <ComboBox ItemsSource="{Binding Versions}" SelectedItem="{Binding SelectedVersion}"
                         HorizontalAlignment="Stretch"
                         AutomationProperties.Name="Vintage Story version" TabIndex="6" />
               <TextBlock Text="Use the recommended version unless you need a compatibility bridge."
-                         Classes="Caption" TextWrapping="Wrap" />
+                         Foreground="{DynamicResource TextFillColorSecondaryBrush}" TextWrapping="Wrap" />
             </StackPanel>
           </Grid>
-        </suki:GlassCard>
+        </Border>
 
       </StackPanel>
     </ScrollViewer>
 
     <Grid Grid.Row="1" ColumnDefinitions="Auto,*,Auto" Margin="0,16,0,0">
       <Button Grid.Column="0" Content="Back" Command="{Binding BackCommand}" TabIndex="8" />
-      <Button Grid.Column="2" Content="Review" Classes="Flat"
+      <Button Grid.Column="2" Content="Review" Classes="accent"
               IsEnabled="{Binding CanContinue}" Command="{Binding ContinueCommand}" TabIndex="7" />
     </Grid>
   </Grid>
diff --git a/Optimum.Installer/Views/PrerequisitesView.axaml b/Optimum.Installer/Views/PrerequisitesView.axaml
index 2bd50c57..953092c5 100644
--- a/Optimum.Installer/Views/PrerequisitesView.axaml
+++ b/Optimum.Installer/Views/PrerequisitesView.axaml
@@ -1,6 +1,5 @@
 <UserControl xmlns="https://github.com/avaloniaui"
              xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
-             xmlns:suki="https://github.com/kikipoulet/SukiUI"
              xmlns:vm="using:Optimum.Installer.ViewModels"
              xmlns:conv="using:Optimum.Installer.Views"
              x:Class="Optimum.Installer.Views.PrerequisitesView"
@@ -18,24 +17,25 @@
     <ScrollViewer Grid.Row="1" HorizontalScrollBarVisibility="Disabled">
       <StackPanel Spacing="12">
 
-        <suki:GlassCard IsVisible="{Binding RepoRootMissing}">
+        <Border Classes="Card" IsVisible="{Binding RepoRootMissing}">
           <StackPanel Spacing="10">
-            <TextBlock Text="Optimum source" Classes="h5" />
+            <TextBlock Text="Optimum source" FontSize="17" FontWeight="SemiBold" />
             <TextBlock Text="The matching public Optimum source is downloaded into your user cache. Vintage Story files are fetched later on this computer and are never bundled with the installer."
-                       Classes="Caption" TextWrapping="Wrap" />
+                       Foreground="{DynamicResource TextFillColorSecondaryBrush}" TextWrapping="Wrap" />
             <StackPanel Orientation="Horizontal" Spacing="12" VerticalAlignment="Center">
-              <Button Content="Download source" Classes="Flat"
+              <Button Content="Download source" Classes="accent"
                       IsVisible="{Binding CanAcquireSource}"
                       IsEnabled="{Binding !AcquiringSource}"
                       Command="{Binding AcquireSourceCommand}" />
               <ProgressBar IsIndeterminate="True" Width="130" Height="4"
                            IsVisible="{Binding AcquiringSource}"
                            AutomationProperties.Name="Downloading Optimum source" />
-              <TextBlock Text="{Binding SourceStatus}" Classes="Caption"
+              <TextBlock Text="{Binding SourceStatus}"
+                         Foreground="{DynamicResource TextFillColorSecondaryBrush}"
                          VerticalAlignment="Center" TextWrapping="Wrap" />
             </StackPanel>
           </StackPanel>
-        </suki:GlassCard>
+        </Border>
 
         <ItemsControl ItemsSource="{Binding AttentionRows}">
           <ItemsControl.ItemsPanel>
@@ -43,50 +43,51 @@
           </ItemsControl.ItemsPanel>
           <ItemsControl.ItemTemplate>
             <DataTemplate x:DataType="vm:PrerequisiteRowViewModel">
-              <suki:GlassCard>
+              <Border Classes="Card">
                 <Grid ColumnDefinitions="*,Auto">
                   <StackPanel Grid.Column="0" Spacing="4">
                     <StackPanel Orientation="Horizontal" Spacing="10">
-                      <TextBlock Text="{Binding Name}" FontWeight="DemiBold" />
-                      <TextBlock Text="{Binding StatusLabel}" FontWeight="DemiBold"
+                      <TextBlock Text="{Binding Name}" FontWeight="SemiBold" />
+                      <TextBlock Text="{Binding StatusLabel}" FontWeight="SemiBold"
                                  Foreground="{Binding IsOptional, Converter={x:Static conv:InstallerConverters.StatusBrush}}"
                                  VerticalAlignment="Center" />
                     </StackPanel>
-                    <TextBlock Text="{Binding Detail}" Classes="Caption" TextWrapping="Wrap" />
+                    <TextBlock Text="{Binding Detail}"
+                               Foreground="{DynamicResource TextFillColorSecondaryBrush}" TextWrapping="Wrap" />
                     <SelectableTextBlock Text="{Binding ManualCommand}"
-                                         FontFamily="{DynamicResource MonoFont}"
+                                         FontFamily="Cascadia Code, Consolas, monospace"
                                          IsVisible="{Binding ManualCommand, Converter={x:Static StringConverters.IsNotNullOrEmpty}}" />
                   </StackPanel>
-                  <Button Grid.Column="1" Content="{Binding ActionLabel}" Classes="Flat" Margin="16,0,0,0"
+                  <Button Grid.Column="1" Content="{Binding ActionLabel}" Classes="accent" Margin="16,0,0,0"
                           VerticalAlignment="Center"
                           IsVisible="{Binding ActionLabel, Converter={x:Static StringConverters.IsNotNullOrEmpty}}"
                           Command="{Binding ActionCommand}"
                           ToolTip.Tip="{Binding ActionDetail}" />
                 </Grid>
-              </suki:GlassCard>
+              </Border>
             </DataTemplate>
           </ItemsControl.ItemTemplate>
         </ItemsControl>
 
-        <suki:GlassCard IsVisible="{Binding HasReadyTools}">
+        <Border Classes="Card" IsVisible="{Binding HasReadyTools}">
           <Grid ColumnDefinitions="Auto,*">
             <TextBlock Grid.Column="0" Text="&#x2713;" FontWeight="Bold"
-                       Foreground="{DynamicResource SukiPrimaryColor}"
+                       Foreground="{DynamicResource SystemFillColorSuccessBrush}"
                        FontSize="18" Margin="0,0,12,0" VerticalAlignment="Top" />
             <StackPanel Grid.Column="1" Spacing="4">
-              <TextBlock Text="System tools ready" FontWeight="DemiBold" />
+              <TextBlock Text="System tools ready" FontWeight="SemiBold" />
               <SelectableTextBlock Text="{Binding ReadySummary}" TextWrapping="Wrap"
-                                   FontFamily="{DynamicResource MonoFont}" />
+                                   FontFamily="Cascadia Code, Consolas, monospace" />
             </StackPanel>
           </Grid>
-        </suki:GlassCard>
+        </Border>
 
       </StackPanel>
     </ScrollViewer>
 
     <StackPanel Grid.Row="2" Orientation="Horizontal"
                 HorizontalAlignment="Right" Margin="0,16,0,0">
-      <Button Content="Continue" Classes="Flat"
+      <Button Content="Continue" Classes="accent"
               IsEnabled="{Binding CanContinue}"
               Command="{Binding ContinueCommand}" />
     </StackPanel>
diff --git a/Optimum.Installer/Views/ProgressView.axaml b/Optimum.Installer/Views/ProgressView.axaml
index 1828c87f..affc680c 100644
--- a/Optimum.Installer/Views/ProgressView.axaml
+++ b/Optimum.Installer/Views/ProgressView.axaml
@@ -1,50 +1,51 @@
 <UserControl xmlns="https://github.com/avaloniaui"
              xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
-             xmlns:suki="https://github.com/kikipoulet/SukiUI"
              xmlns:vm="using:Optimum.Installer.ViewModels"
              xmlns:conv="using:Optimum.Installer.Views"
              x:Class="Optimum.Installer.Views.ProgressView"
              x:DataType="vm:ProgressViewModel">
   <Grid RowDefinitions="Auto,*,Auto">
 
-    <suki:GlassCard Grid.Row="0" Padding="20,18">
-      <Grid ColumnDefinitions="Auto,*" VerticalAlignment="Center">
-        <Panel Grid.Column="0" Width="84" Height="84" Margin="0,0,22,0" VerticalAlignment="Center">
-          <suki:CircleProgressBar Value="{Binding Percent}" StrokeWidth="7" Width="84" Height="84" />
-          <TextBlock Text="{Binding PercentLabel}" FontWeight="DemiBold" FontSize="18"
-                     HorizontalAlignment="Center" VerticalAlignment="Center" />
-        </Panel>
-
-        <StackPanel Grid.Column="1" Spacing="5" VerticalAlignment="Center">
-          <TextBlock Text="{Binding PhaseLabel}" Classes="h5" />
-          <TextBlock Text="{Binding StatusDetail}" Classes="Caption" TextWrapping="Wrap"
-                     IsVisible="{Binding StatusDetail, Converter={x:Static StringConverters.IsNotNullOrEmpty}}" />
-          <Grid ColumnDefinitions="*,Auto" Margin="0,3,0,0">
-            <TextBlock Grid.Column="0" Text="Runs locally. The first build takes the longest." Classes="Caption"
-                       VerticalAlignment="Center" />
-            <StackPanel Grid.Column="1" Orientation="Horizontal" Spacing="14" VerticalAlignment="Center">
-              <TextBlock Classes="Caption">
-                <Run Text="Elapsed " /><Run Text="{Binding Elapsed}" FontFamily="{DynamicResource MonoFont}" />
-              </TextBlock>
-              <TextBlock Text="{Binding EstimatedRemaining}" Classes="Caption"
-                         IsVisible="{Binding EstimatedRemaining, Converter={x:Static StringConverters.IsNotNullOrEmpty}}" />
-            </StackPanel>
-          </Grid>
-        </StackPanel>
-      </Grid>
-    </suki:GlassCard>
+    <Border Classes="Card" Grid.Row="0" Padding="20,18">
+      <StackPanel x:Name="ProgressText" Spacing="8">
+        <Grid ColumnDefinitions="*,Auto">
+          <TextBlock Grid.Column="0" Text="{Binding PhaseLabel}" FontSize="17" FontWeight="SemiBold"
+                     VerticalAlignment="Center" />
+          <TextBlock Grid.Column="1" Text="{Binding PercentLabel}" FontSize="17" FontWeight="SemiBold"
+                     VerticalAlignment="Center" />
+        </Grid>
+        <!-- WinUI-styled indeterminate progress bar. -->
+        <ProgressBar IsIndeterminate="True" Height="4" />
+        <TextBlock Text="{Binding StatusDetail}"
+                   Foreground="{DynamicResource TextFillColorSecondaryBrush}" TextWrapping="Wrap"
+                   IsVisible="{Binding StatusDetail, Converter={x:Static StringConverters.IsNotNullOrEmpty}}" />
+        <Grid ColumnDefinitions="*,Auto" Margin="0,3,0,0">
+          <TextBlock Grid.Column="0" Text="Runs locally. The first build takes the longest."
+                     Foreground="{DynamicResource TextFillColorSecondaryBrush}"
+                     VerticalAlignment="Center" />
+          <StackPanel Grid.Column="1" Orientation="Horizontal" Spacing="14" VerticalAlignment="Center">
+            <TextBlock Foreground="{DynamicResource TextFillColorSecondaryBrush}">
+              <Run Text="Elapsed " /><Run Text="{Binding Elapsed}" FontFamily="Cascadia Code, Consolas, monospace" />
+            </TextBlock>
+            <TextBlock Text="{Binding EstimatedRemaining}"
+                       Foreground="{DynamicResource TextFillColorSecondaryBrush}"
+                       IsVisible="{Binding EstimatedRemaining, Converter={x:Static StringConverters.IsNotNullOrEmpty}}" />
+          </StackPanel>
+        </Grid>
+      </StackPanel>
+    </Border>
 
-    <suki:GlassCard Grid.Row="1" Margin="0,12,0,0" Padding="0">
+    <Border Classes="Card" Grid.Row="1" Margin="0,12,0,0" Padding="0">
       <Grid RowDefinitions="Auto,*">
-        <TextBlock Grid.Row="0" Text="Build log" Classes="h5" Margin="16,14,16,8" />
-        <Border Grid.Row="1" Background="{DynamicResource InsetSurfaceBrush}"
-                BorderBrush="{DynamicResource InsetBorderBrush}" BorderThickness="0,1,0,0"
-                CornerRadius="0,0,12,12">
+        <TextBlock Grid.Row="0" Text="Build log" FontSize="17" FontWeight="SemiBold" Margin="16,14,16,8" />
+        <Border Grid.Row="1" Background="{DynamicResource LayerFillColorDefaultBrush}"
+                BorderBrush="{DynamicResource CardStrokeColorDefaultBrush}" BorderThickness="0,1,0,0"
+                CornerRadius="0,0,8,8">
           <ScrollViewer x:Name="LogScroller" Padding="16,10">
             <ItemsControl ItemsSource="{Binding Log}">
               <ItemsControl.ItemTemplate>
                 <DataTemplate x:DataType="vm:LogLine">
-                  <TextBlock Text="{Binding Text}" FontFamily="{DynamicResource MonoFont}" FontSize="13"
+                  <TextBlock Text="{Binding Text}" FontFamily="Cascadia Code, Consolas, monospace" FontSize="13"
                              Foreground="{Binding Level, Converter={x:Static conv:InstallerConverters.LogLevelBrush}}"
                              TextWrapping="Wrap" Margin="0,1.5" />
                 </DataTemplate>
@@ -53,17 +54,18 @@
           </ScrollViewer>
         </Border>
       </Grid>
-    </suki:GlassCard>
+    </Border>
 
     <Grid Grid.Row="2" ColumnDefinitions="*,Auto" Margin="0,14,0,0">
-      <suki:GlassCard Grid.Column="0" Margin="0,0,12,0" IsVisible="{Binding ConfirmCancel}">
+      <Border Classes="Card" Grid.Column="0" Margin="0,0,12,0" IsVisible="{Binding ConfirmCancel}">
         <StackPanel Orientation="Horizontal" Spacing="12" VerticalAlignment="Center">
-          <TextBlock Text="Stop the installation?" Classes="Warning" FontWeight="DemiBold"
+          <TextBlock Text="Stop the installation?"
+                     Foreground="{DynamicResource SystemFillColorCautionBrush}" FontWeight="SemiBold"
                      VerticalAlignment="Center" />
           <Button Content="Keep going" Command="{Binding KeepInstallingCommand}" />
-          <Button Content="Stop" Classes="Flat" Command="{Binding CancelCommand}" />
+          <Button Content="Stop" Classes="accent" Command="{Binding CancelCommand}" />
         </StackPanel>
-      </suki:GlassCard>
+      </Border>
       <Button Grid.Column="1" Content="Cancel"
               IsEnabled="{Binding !CancelRequested}"
               IsVisible="{Binding !ConfirmCancel}"
diff --git a/Optimum.Installer/app.manifest b/Optimum.Installer/app.manifest
index 4b5817ca..1208de04 100644
--- a/Optimum.Installer/app.manifest
+++ b/Optimum.Installer/app.manifest
@@ -1,6 +1,28 @@
 <?xml version="1.0" encoding="utf-8"?>
 <assembly manifestVersion="1.0" xmlns="urn:schemas-microsoft-com:asm.v1">
   <assemblyIdentity version="1.0.0.0" name="Optimum.Installer" />
+
+  <compatibility xmlns="urn:schemas-microsoft-com:compatibility.v1">
+    <application>
+      <!-- Windows 10 and Windows 11 -->
+      <supportedOS Id="{8e0f7a12-bfb3-4fe8-b9a5-48fd50a15a9a}" />
+      <!-- Windows 8.1 -->
+      <supportedOS Id="{1f676c76-80e1-4239-95bb-83d0f6d0da78}" />
+      <!-- Windows 8 -->
+      <supportedOS Id="{4a2f28e3-53b9-4441-ba9c-d69d4a4a6e38}" />
+      <!-- Windows 7 -->
+      <supportedOS Id="{35138b9a-5d96-4fbd-8e2d-a2440225f93a}" />
+    </application>
+  </compatibility>
+
+  <trustInfo xmlns="urn:schemas-microsoft-com:asm.v2">
+    <security>
+      <requestedPrivileges xmlns="urn:schemas-microsoft-com:asm.v3">
+        <requestedExecutionLevel level="asInvoker" uiAccess="false" />
+      </requestedPrivileges>
+    </security>
+  </trustInfo>
+
   <application xmlns="urn:schemas-microsoft-com:asm.v3">
     <windowsSettings>
       <dpiAware xmlns="http://schemas.microsoft.com/SMI/2005/WindowsSettings">true/pm</dpiAware>
diff --git a/Optimum.Tests/adaptive-radius-controller-tests.cs b/Optimum.Tests/adaptive-radius-controller-tests.cs
index ec5277dc..1e7eb447 100644
--- a/Optimum.Tests/adaptive-radius-controller-tests.cs
+++ b/Optimum.Tests/adaptive-radius-controller-tests.cs
@@ -230,4 +230,32 @@ public void FullCycle_ExplorationSpikeThenRecovery()
         Assert.True(recoveredRadius > contractedRadius,
             $"Expected radius to recover above {contractedRadius}, got {recoveredRadius}");
     }
+
+    [Fact]
+    public void FloorExceedingConfiguredMax_DoesNotThrowAndClampsToMax()
+    {
+        // When user configures floor = 48 (engine max) but plays at lower view distance (e.g. 12)
+        SetAdaptiveRadiusConfig(high: 60, low: 20, floor: 48);
+        var ctrl = new OptimumAdaptiveRadiusController(12);
+
+        // Tick under spike should not throw ArgumentException from Math.Clamp
+        ctrl.Tick(120, 12);
+        Assert.Equal(12, ctrl.EffectiveRadius);
+    }
+
+    [Fact]
+    public void SupportsEngineMaxRadiusOf48()
+    {
+        SetAdaptiveRadiusConfig(high: 60, low: 20, floor: 32);
+        var ctrl = new OptimumAdaptiveRadiusController(48);
+        Assert.Equal(48, ctrl.EffectiveRadius);
+
+        for (int i = 0; i < 20; i++)
+        {
+            ctrl.Tick(120, 48);
+        }
+
+        Assert.True(ctrl.EffectiveRadius >= 32);
+        Assert.True(ctrl.EffectiveRadius < 48);
+    }
 }
diff --git a/Optimum.Tests/installer-release-coverage-tests.cs b/Optimum.Tests/installer-release-coverage-tests.cs
index 7fc4e609..67249188 100644
--- a/Optimum.Tests/installer-release-coverage-tests.cs
+++ b/Optimum.Tests/installer-release-coverage-tests.cs
@@ -39,8 +39,8 @@ public void InstallerAndBootstrapsShareIlspycmdCompatibilityFile()
         JsonElement minimum = document.RootElement.GetProperty("minimumVersion");
         JsonElement maximum = document.RootElement.GetProperty("maximumVersion");
 
-        Assert.Equal("10.1.0.8386", minimum.GetString());
-        Assert.Equal("10.1.1.8388", maximum.GetString());
+        Assert.Equal("11.0.0.9375", minimum.GetString());
+        Assert.Equal("11.0.0.9375", maximum.GetString());
         Assert.Contains(".config/ilspycmd-compat.json", Read("scripts/install-linux.sh"));
         Assert.Contains(".config/ilspycmd-compat.json", Read("scripts/bootstrap.sh"));
         Assert.Contains(".config/ilspycmd-compat.json", Read("scripts/bootstrap.ps1"));
diff --git a/patches/VintagestoryApi/VintagestoryAPI.csproj.patch b/patches/VintagestoryApi/VintagestoryAPI.csproj.patch
deleted file mode 100644
index c5c3cf33..00000000
--- a/patches/VintagestoryApi/VintagestoryAPI.csproj.patch
+++ /dev/null
@@ -1,26 +0,0 @@
-diff --git a/VintagestoryApi/VintagestoryAPI.csproj b/VintagestoryApi/VintagestoryAPI.csproj
-index afbd3bc..2ebb1eb 100644
---- a/VintagestoryApi/VintagestoryAPI.csproj
-+++ b/VintagestoryApi/VintagestoryAPI.csproj
-@@ -37,19 +37,21 @@
-     <Compile Remove="Config\AdaptiveWorkerController.cs" />
-     <Compile Remove="Config\AdaptiveTessWorkerController.cs" />
-     <Compile Remove="Config\OptimumAdaptiveRadiusController.cs" />
-     <Compile Remove="Config\OptimumAnimLod.cs" />
-     <Compile Remove="Config\OptimumConfig.cs" />
-+    <Compile Remove="Client\Model\Mesh\OptimumMeshPartPool.cs" />
-     <Compile Remove="Config\OptimumGreedyMesher.cs" />
-     <Compile Remove="Config\OptimumThreadGuard.cs" />
-     <Compile Remove="Config\OptimumWorkerInstances.cs" />
-     <Compile Remove="Config\OptimumBoundedHandoff.cs" />
-     <Compile Remove="Config\OptimumDispatchClaim.cs" />
-     <Compile Remove="Config\OptimumTesselationWorkerRegistry.cs" />
-     <Compile Remove="Config\OptimumTesselationSafetyGate.cs" />
-     <Compile Remove="Config\OptimumWorldgenSafetyGate.cs" />
-     <Compile Remove="Config\optimum-worldgen-footprint-lease.cs" />
-     <Compile Remove="Config\optimum-api-bridge.cs" />
-+    <Compile Remove="Config\OptimumChunkVisibilityBfs.cs" />
-   </ItemGroup>
- 
-   <ItemGroup>
-     <PackageReference Include="Newtonsoft.Json" Version="13.0.4" />
diff --git a/patches/VintagestoryLib/Vintagestory.Client.NoObf/ClientEventManager.cs.patch b/patches/VintagestoryLib/Vintagestory.Client.NoObf/ClientEventManager.cs.patch
index 33308e46..e15c135b 100644
--- a/patches/VintagestoryLib/Vintagestory.Client.NoObf/ClientEventManager.cs.patch
+++ b/patches/VintagestoryLib/Vintagestory.Client.NoObf/ClientEventManager.cs.patch
@@ -1,5 +1,5 @@
 diff --git a/VintagestoryLib/Vintagestory.Client.NoObf/ClientEventManager.cs b/VintagestoryLib/Vintagestory.Client.NoObf/ClientEventManager.cs
-index 5e61808..1f131b0 100644
+index 11a0fd0..34d04b1 100644
 --- a/VintagestoryLib/Vintagestory.Client.NoObf/ClientEventManager.cs
 +++ b/VintagestoryLib/Vintagestory.Client.NoObf/ClientEventManager.cs
 @@ -181,15 +181,21 @@ public class ClientEventManager : EventManager
@@ -25,4 +25,4 @@ index 5e61808..1f131b0 100644
  
  	public void TriggerLightingUpdate(int oldBlockId, int newBlockId, BlockPos pos, Dictionary<BlockPos, BlockUpdate> blockUpdatesBulk = null)
  	{
- 		Trigger(this.OnUpdateLighting?.GetInvocationList(), "OnUpdateLighting", delegate(UpdateLightingDelegate dele)
+ 		Trigger(OnUpdateLighting?.GetInvocationList(), "OnUpdateLighting", delegate(UpdateLightingDelegate dele)
diff --git a/patches/VintagestoryLib/Vintagestory.Client.NoObf/InventoryItemRenderer.cs.patch b/patches/VintagestoryLib/Vintagestory.Client.NoObf/InventoryItemRenderer.cs.patch
index 8ec74250..90976a39 100644
--- a/patches/VintagestoryLib/Vintagestory.Client.NoObf/InventoryItemRenderer.cs.patch
+++ b/patches/VintagestoryLib/Vintagestory.Client.NoObf/InventoryItemRenderer.cs.patch
@@ -1,5 +1,5 @@
 diff --git a/VintagestoryLib/Vintagestory.Client.NoObf/InventoryItemRenderer.cs b/VintagestoryLib/Vintagestory.Client.NoObf/InventoryItemRenderer.cs
-index 0a45eb1..c7d80b3 100644
+index 35bb9ac..8193b14 100644
 --- a/VintagestoryLib/Vintagestory.Client.NoObf/InventoryItemRenderer.cs
 +++ b/VintagestoryLib/Vintagestory.Client.NoObf/InventoryItemRenderer.cs
 @@ -13,10 +13,16 @@ namespace Vintagestory.Client.NoObf;
@@ -14,12 +14,12 @@ index 0a45eb1..c7d80b3 100644
 +	[System.ThreadStatic]
 +	private static ItemRenderInfo optimumGuiRenderInfoScratch;
 +
- 	private Dictionary<string, LoadedTexture> StackSizeTextures = new Dictionary<string, LoadedTexture>();
+ 	private Dictionary<string, LoadedTexture> StackSizeTextures;
  
  	private MeshRef quadModelRef;
  
  	private CairoFont stackSizeFont;
-@@ -237,11 +243,33 @@ public class InventoryItemRenderer : IRenderer, IDisposable
+@@ -243,11 +249,33 @@ public class InventoryItemRenderer : IRenderer, IDisposable
  	public void RenderItemstackToGui(ItemSlot inSlot, double posX, double posY, double posZ, float size, int color, float dt, bool shading = true, bool origRotate = false, bool showStackSize = true)
  	{
  		try
@@ -54,7 +54,7 @@ index 0a45eb1..c7d80b3 100644
  				return;
  			}
  			bool flag = dt == -1.0125f;
-@@ -346,17 +374,31 @@ public class InventoryItemRenderer : IRenderer, IDisposable
+@@ -352,17 +380,31 @@ public class InventoryItemRenderer : IRenderer, IDisposable
  		cairoFont.UnscaledFontsize *= fontSizeMultiplier;
  		return game.api.guiapi.TextTexture.GenTextTexture(stackSize.ToString() ?? "", cairoFont);
  	}
@@ -88,7 +88,7 @@ index 0a45eb1..c7d80b3 100644
  		{
  		case EnumItemRenderTarget.Ground:
  			renderinfo.Transform = itemstack.Collectible.GroundTransform;
-@@ -425,10 +467,33 @@ public class InventoryItemRenderer : IRenderer, IDisposable
+@@ -431,10 +473,33 @@ public class InventoryItemRenderer : IRenderer, IDisposable
  		inSlot.OnBeforeRender(renderinfo);
  		itemstack.Collectible.OnBeforeRender(game.api, itemstack, target, ref renderinfo);
  		return renderinfo;
diff --git a/patches/VintagestoryLib/Vintagestory.Client.NoObf/ShaderRegistry.cs.patch b/patches/VintagestoryLib/Vintagestory.Client.NoObf/ShaderRegistry.cs.patch
index 73f84313..b4fd137b 100644
--- a/patches/VintagestoryLib/Vintagestory.Client.NoObf/ShaderRegistry.cs.patch
+++ b/patches/VintagestoryLib/Vintagestory.Client.NoObf/ShaderRegistry.cs.patch
@@ -1,5 +1,5 @@
 diff --git a/VintagestoryLib/Vintagestory.Client.NoObf/ShaderRegistry.cs b/VintagestoryLib/Vintagestory.Client.NoObf/ShaderRegistry.cs
-index 4a24e75..edaaa34 100644
+index d3edef9..edaaa34 100644
 --- a/VintagestoryLib/Vintagestory.Client.NoObf/ShaderRegistry.cs
 +++ b/VintagestoryLib/Vintagestory.Client.NoObf/ShaderRegistry.cs
 @@ -1,8 +1,10 @@
@@ -116,7 +116,7 @@ index 4a24e75..edaaa34 100644
 +			for (int i = 0; i < nextPassId; i++)
  			{
 -				LoadShaderProgram(shaderProgram, ScreenManager.Platform.UseSSBOs);
--				flag = shaderProgram.Compile() && flag;
+-				flag = shaderProgram.Compile() & flag;
 +				ShaderProgram shaderProgram = shaderPrograms[i];
 +				if (shaderProgram != null)
 +				{
diff --git a/patches/VintagestoryLib/Vintagestory.Common/EventManager.cs.patch b/patches/VintagestoryLib/Vintagestory.Common/EventManager.cs.patch
index 2c13f4ce..62c85452 100644
--- a/patches/VintagestoryLib/Vintagestory.Common/EventManager.cs.patch
+++ b/patches/VintagestoryLib/Vintagestory.Common/EventManager.cs.patch
@@ -1,5 +1,5 @@
 diff --git a/VintagestoryLib/Vintagestory.Common/EventManager.cs b/VintagestoryLib/Vintagestory.Common/EventManager.cs
-index 842d31f..7309654 100644
+index 1e91e34..ead904e 100644
 --- a/VintagestoryLib/Vintagestory.Common/EventManager.cs
 +++ b/VintagestoryLib/Vintagestory.Common/EventManager.cs
 @@ -27,10 +27,26 @@ public abstract class EventManager
@@ -29,19 +29,14 @@ index 842d31f..7309654 100644
  	public abstract string CommandPrefix { get; }
  
  	public abstract long InWorldEllapsedMs { get; }
-@@ -88,15 +104,22 @@ public abstract class EventManager
- 		}
- 	}
- 
- 	public virtual void TriggerOnGetClimate(ref ClimateCondition climate, BlockPos pos, EnumGetClimateMode mode = EnumGetClimateMode.WorldGenValues, double totalDays = 0.0)
+@@ -92,11 +108,18 @@ public abstract class EventManager
  	{
--		if (this.OnGetClimate == null)
-+		OnGetClimateDelegate current = this.OnGetClimate;
-+		if (current == null)
+ 		if (OnGetClimate == null)
  		{
  			return;
  		}
--		Delegate[] invocationList = this.OnGetClimate.GetInvocationList();
+-		Delegate[] invocationList = OnGetClimate.GetInvocationList();
++		OnGetClimateDelegate current = OnGetClimate;
 +		// Optimum: cache the invocation list. Rebuild only when the delegate reference changes.
 +		if (!ReferenceEquals(current, optimumCachedClimateDelegate))
 +		{
@@ -54,19 +49,14 @@ index 842d31f..7309654 100644
  			OnGetClimateDelegate onGetClimateDelegate = (OnGetClimateDelegate)invocationList[i];
  			try
  			{
-@@ -110,15 +133,22 @@ public abstract class EventManager
- 		}
- 	}
- 
- 	public virtual void TriggerOnGetWindSpeed(Vec3d pos, ref Vec3d windSpeed)
+@@ -114,11 +137,18 @@ public abstract class EventManager
  	{
--		if (this.OnGetWindSpeed == null)
-+		OnGetWindSpeedDelegate current = this.OnGetWindSpeed;
-+		if (current == null)
+ 		if (OnGetWindSpeed == null)
  		{
  			return;
  		}
--		Delegate[] invocationList = this.OnGetWindSpeed.GetInvocationList();
+-		Delegate[] invocationList = OnGetWindSpeed.GetInvocationList();
++		OnGetWindSpeedDelegate current = OnGetWindSpeed;
 +		// Optimum: cache the invocation list. Rebuild only when the delegate reference changes.
 +		if (!ReferenceEquals(current, optimumCachedWindDelegate))
 +		{
diff --git a/scripts/bootstrap.ps1 b/scripts/bootstrap.ps1
index a19365b0..46c07976 100644
--- a/scripts/bootstrap.ps1
+++ b/scripts/bootstrap.ps1
@@ -173,8 +173,8 @@ function Get-IlspycmdVersionRange {
     $manifest = Join-Path $repoRoot '.config/ilspycmd-compat.json'
     if (-not (Test-Path $manifest)) {
         return [pscustomobject]@{
-            Minimum = [Version]'10.1.0.8386'
-            Maximum = [Version]'10.1.1.8388'
+            Minimum = [Version]'11.0.0.9375'
+            Maximum = [Version]'11.0.0.9375'
         }
     }
 
@@ -235,7 +235,7 @@ function Install-IlspycmdIfMissing {
 function Repair-BaseCtorCalls {
     param([string[]]$Roots)
 
-    $callRe = [regex]'[ \t]*(base|this)\._002Ector\(((?:[^()]|\([^()]*\))*)\);\n'
+    $callRe = [regex]'[ \t]*(?:(base|this)|\(\([\w.]+\)this\))\._002Ector\(((?:[^()]|\([^()]*\))*)\);\n'
     $sigRe = [regex]'((?:public|private|protected|internal|static)[ \w]*\s\w+\(([^()]*)\)\s*\n)(\t*\{\n)'
 
     function local:Invoke-FixOnce([string]$text) {
@@ -252,6 +252,9 @@ function Repair-BaseCtorCalls {
             $callM = $callRe.Match($body)
             if (-not $callM.Success) { continue }
             $kind = $callM.Groups[1].Value
+            # The cast form ((BaseType)this)._002Ector(...) leaves group 1 empty;
+            # it is always a base constructor chain.
+            if (-not $kind) { $kind = 'base' }
             $ctorArgs = $callM.Groups[2].Value
             $newBody = $body.Substring(0, $callM.Index) + $body.Substring($callM.Index + $callM.Length)
             $header = $sigM.Groups[1].Value
@@ -660,7 +663,7 @@ try {
                 $actual = (Get-FileHash -Path $innoPartial -Algorithm SHA256).Hash.ToLowerInvariant()
                 if ($actual -ne $expected) {
                     Remove-Item -Force -ErrorAction SilentlyContinue $innoPartial
-                    throw "SHA-256 verification failed for $assetName: expected $expected, got $actual"
+                    throw "SHA-256 verification failed for ${assetName}: expected $expected, got $actual"
                 }
             }
 
@@ -699,9 +702,18 @@ try {
                 throw "Extraction failed: Vintagestory.exe not found in $ClientArchive payload"
             }
 
+            if (Test-Path $winVanillaDir) {
+                Remove-Item -Recurse -Force $winVanillaDir -ErrorAction SilentlyContinue
+            }
             New-Item -ItemType Directory -Force -Path $winVanillaDir | Out-Null
-            Get-ChildItem -Path $sourceRoot -Force | ForEach-Object {
-                Move-Item -Path $_.FullName -Destination $winVanillaDir -Force
+            if ($isWin -and (Get-Command robocopy.exe -ErrorAction SilentlyContinue)) {
+                & robocopy.exe "$sourceRoot" "$winVanillaDir" /E /MOVE /NFL /NDL /NJH /NJS /NP /R:3 /W:1 *>&1 | Out-Null
+                if ($LASTEXITCODE -ge 8) { throw "robocopy failed (exit code $LASTEXITCODE) moving extracted files to $winVanillaDir." }
+                $global:LASTEXITCODE = 0
+            } else {
+                Get-ChildItem -Path $sourceRoot -Force | ForEach-Object {
+                    Move-Item -Path $_.FullName -Destination $winVanillaDir -Force
+                }
             }
         } finally {
             if (Test-Path $extractRoot) { Remove-Item -Recurse -Force $extractRoot -ErrorAction SilentlyContinue }
diff --git a/scripts/bootstrap.sh b/scripts/bootstrap.sh
index 0acb504d..b85fba7b 100644
--- a/scripts/bootstrap.sh
+++ b/scripts/bootstrap.sh
@@ -94,7 +94,7 @@ ilspycmd_version_bounds() {
     grep -oE '"[0-9]+\.[0-9]+\.[0-9]+\.[0-9]+"' "$manifest" | tr -d '"'
     return
   fi
-  printf '%s\n' '10.1.0.8386' '10.1.1.8388'
+  printf '%s\n' '11.0.0.9375' '11.0.0.9375'
 }
 
 ilspycmd_version_at_least() {
@@ -1465,7 +1465,7 @@ if [[ "${#ownership_conflicts[@]}" -gt 0 ]]; then
   exit 1
 fi
 
-if [[ -d "$patches_dir" ]] && find "$patches_dir" -name '*.patch' -print 2>/dev/null | head -n 1 | grep -q .; then
+if [[ -d "$patches_dir" ]] && (set +o pipefail; find "$patches_dir" -name '*.patch' -print 2>/dev/null | head -n 1 | grep -q .); then
 
   # ZIP downloads (non-clone) lack a .git/ directory. git add and git apply
   # both exit 128 without one. Create a temporary repo so patches can apply.
diff --git a/scripts/fix-base-ctor-calls.py b/scripts/fix-base-ctor-calls.py
index 8750067a..a7889a6b 100755
--- a/scripts/fix-base-ctor-calls.py
+++ b/scripts/fix-base-ctor-calls.py
@@ -10,12 +10,22 @@
 code first); moving it to the initializer position doesn't change what that
 code does, since real field initializers always run after the base
 constructor per C# spec, which is the order this produces either way.
+
+ILSpy 11 introduced a third spelling for the base call: a cast-to-base-type
+receiver, `((BaseType)this)._002Ector(args);`. That is still a base
+constructor chain, so it maps to `: base(args)`.
 """
 import re
 import sys
 import glob
 
-CALL_RE = re.compile(r'[ \t]*(base|this)\._002Ector\(((?:[^()]|\([^()]*\))*)\);\n')
+# Matches the three spellings ILSpy emits for a constructor chain call:
+#   base._002Ector(args);              -> : base(args)
+#   this._002Ector(args);              -> : this(args)
+#   ((BaseType)this)._002Ector(args);  -> : base(args)   (ILSpy 11 cast form)
+CALL_RE = re.compile(
+    r'[ \t]*(?:(base|this)|\(\([\w.]+\)this\))\._002Ector'
+    r'\(((?:[^()]|\([^()]*\))*)\);\n')
 SIG_RE = re.compile(
     r'((?:public|private|protected|internal|static)[ \w]*\s\w+\(([^()]*)\)\s*\n)(\t*\{\n)'
 )
@@ -39,6 +49,10 @@ def fix_once(text):
         if not call_m:
             continue
         kind, args = call_m.group(1), call_m.group(2)
+        # The cast form ((BaseType)this)._002Ector(...) leaves group(1) unset;
+        # it is always a base constructor chain.
+        if not kind:
+            kind = 'base'
         new_body = body[:call_m.start()] + body[call_m.end():]
         header, brace_line = sig_m.group(1), sig_m.group(3)
         new_header = header.rstrip('\n') + f'\n\t\t: {kind}({args})\n'
diff --git a/scripts/install-linux-legacy.sh b/scripts/install-linux-legacy.sh
index da1b8205..82d5a8d8 100644
--- a/scripts/install-linux-legacy.sh
+++ b/scripts/install-linux-legacy.sh
@@ -134,7 +134,7 @@ activate_user_dotnet() {
 
 pinned_ilspycmd_version() {
     local manifest="$REPO_ROOT/.config/dotnet-tools.json"
-    local fallback="10.1.1.8388"
+    local fallback="11.0.0.9375"
     [[ -f "$manifest" ]] || { printf '%s\n' "$fallback"; return; }
     local parsed
     parsed=$(grep -A 4 '"ilspycmd"' "$manifest" | grep -m 1 '"version"' | sed -E 's/.*"version"[[:space:]]*:[[:space:]]*"([^"]+)".*/\1/' || true)
@@ -147,7 +147,7 @@ ilspycmd_version_bounds() {
         grep -oE '"[0-9]+\.[0-9]+\.[0-9]+\.[0-9]+"' "$manifest" | tr -d '"'
         return
     fi
-    printf '%s\n' '10.1.0.8386' '10.1.1.8388'
+    printf '%s\n' '11.0.0.9375' '11.0.0.9375'
 }
 
 ilspycmd_version_at_least() {
diff --git a/scripts/install-linux.sh b/scripts/install-linux.sh
index 7d1b2b4b..ef2e7e48 100755
--- a/scripts/install-linux.sh
+++ b/scripts/install-linux.sh
@@ -184,7 +184,7 @@ activate_user_dotnet() {
 
 pinned_ilspycmd_version() {
     local manifest="$REPO_ROOT/.config/dotnet-tools.json"
-    local fallback="10.1.1.8388"
+    local fallback="11.0.0.9375"
     [[ -f "$manifest" ]] || { printf '%s\n' "$fallback"; return; }
     local parsed
     parsed=$(grep -A 4 '"ilspycmd"' "$manifest" | grep -m 1 '"version"' | sed -E 's/.*"version"[[:space:]]*:[[:space:]]*"([^"]+)".*/\1/' || true)
@@ -197,7 +197,7 @@ ilspycmd_version_bounds() {
         grep -oE '"[0-9]+\.[0-9]+\.[0-9]+\.[0-9]+"' "$manifest" | tr -d '"'
         return
     fi
-    printf '%s\n' '10.1.0.8386' '10.1.1.8388'
+    printf '%s\n' '11.0.0.9375' '11.0.0.9375'
 }
 
 ilspycmd_version_at_least() {
diff --git a/scripts/install-windows.ps1 b/scripts/install-windows.ps1
index bea7bed3..8c24ee7b 100644
--- a/scripts/install-windows.ps1
+++ b/scripts/install-windows.ps1
@@ -119,6 +119,9 @@ function Get-ExistingDirectory {
     $candidate = $Path
     while ($candidate -and -not (Test-Path -LiteralPath $candidate -PathType Container)) {
         $parent = Split-Path -Parent $candidate
+        if ($parent -match '^[A-Za-z]:$') {
+            $parent = "$parent\"
+        }
         if (-not $parent -or $parent -eq $candidate) { return $null }
         $candidate = $parent
     }
@@ -586,8 +589,8 @@ function Get-Accepted-ILSpyVersionRange {
     $manifest = Join-Path $Root '.config\ilspycmd-compat.json'
     if (-not (Test-Path $manifest)) {
         return [pscustomobject]@{
-            Minimum = [Version]'10.1.0.8386'
-            Maximum = [Version]'10.1.1.8388'
+            Minimum = [Version]'11.0.0.9375'
+            Maximum = [Version]'11.0.0.9375'
         }
     }
 
@@ -2143,10 +2146,9 @@ By checking the box below and proceeding, you acknowledge that you have read, un
         }
     }
 
-    $q = [char]34
-    $argLine = "-NoProfile -ExecutionPolicy Bypass -File $q$Self$q -Silent -InstallDir $q$dir$q"
-    $argLine += " -VsPath $q$vsP$q"
-    $argLine += " -Version $q$buildVersion$q"
+    $argLine = "-NoProfile -ExecutionPolicy Bypass -File $(ConvertTo-WindowsProcessArgument -Value $Self) -Silent -InstallDir $(ConvertTo-WindowsProcessArgument -Value $dir)"
+    $argLine += " -VsPath $(ConvertTo-WindowsProcessArgument -Value $vsP)"
+    $argLine += " -Version $(ConvertTo-WindowsProcessArgument -Value $buildVersion)"
     if ($script:chkSep.Checked) {
         try {
             $data = Normalize-WindowsDirectoryPath -Path $script:txtData.Text -Name 'DataPath'
@@ -2162,7 +2164,7 @@ By checking the box below and proceeding, you acknowledge that you have read, un
             [System.Windows.Forms.MessageBox]::Show('The data folder cannot be inside the install folder. Choose a separate directory.', 'Optimum', 'OK', 'Warning') | Out-Null
             return
         }
-        $argLine += " -DataPath $q$data$q"
+        $argLine += " -DataPath $(ConvertTo-WindowsProcessArgument -Value $data)"
     }
     if ($script:chkShortcut.Checked) { $argLine += ' -Shortcut' }
     if ($script:chkStartMenu.Checked) { $argLine += ' -StartMenu' }
diff --git a/scripts/package.ps1 b/scripts/package.ps1
index cd71cc2e..80bbac74 100644
--- a/scripts/package.ps1
+++ b/scripts/package.ps1
@@ -261,7 +261,13 @@ try {
     # Fresh copy of the vanilla install. Leaves .vanilla untouched.
     Write-Host "Copying vanilla install to $stageDir..."
     if (Test-Path $stageDir) { Remove-Item -Recurse -Force $stageDir }
-    Copy-Item -Recurse -Force $vanillaDir $stageDir
+    if (Test-WindowsHost -and (Get-Command robocopy.exe -ErrorAction SilentlyContinue)) {
+        & robocopy.exe "$vanillaDir" "$stageDir" /E /NFL /NDL /NJH /NJS /NP /R:3 /W:1 *>&1 | Out-Null
+        if ($LASTEXITCODE -ge 8) { throw "robocopy failed (exit code $LASTEXITCODE)." }
+        $global:LASTEXITCODE = 0
+    } else {
+        Copy-Item -Recurse -Force $vanillaDir $stageDir
+    }
     Copy-Item -Force (Join-Path $repoRoot 'scripts/uninstall.ps1') (Join-Path $stageDir 'uninstall.ps1')
 
     # Keep the engine and built-in mods vanilla. The launcher patches copies at startup.
diff --git a/scripts/regen-one-patch.ps1 b/scripts/regen-one-patch.ps1
new file mode 100644
index 00000000..342ac1c2
--- /dev/null
+++ b/scripts/regen-one-patch.ps1
@@ -0,0 +1,57 @@
+<#
+Regenerate a single patch natively on Windows, mirroring extract-patches.sh:
+  git diff --no-index -U5 between the pristine .baseline file and the modified
+  working-tree file, then rewrite the diff/---/+++ headers to a/<rel> b/<rel>.
+
+Usage:
+  scripts\regen-one-patch.ps1 -Project VintagestoryLib -Rel "Vintagestory.Common/EventManager.cs"
+#>
+[CmdletBinding()]
+param(
+    [Parameter(Mandatory)][string]$Project,
+    [Parameter(Mandatory)][string]$Rel   # path relative to the project dir, forward slashes
+)
+
+$ErrorActionPreference = 'Stop'
+$repoRoot = Split-Path -Parent $PSScriptRoot
+
+# Vanilla decompiled projects live under build/.
+$vanilla = @('VintagestoryLib', 'Vintagestory')
+if ($vanilla -contains $Project) {
+    $workFile = Join-Path $repoRoot "build/$Project/$Rel"
+} else {
+    $workFile = Join-Path $repoRoot "$Project/$Rel"
+}
+$baseFile  = Join-Path $repoRoot ".baseline/$Project/$Rel"
+$patchFile = Join-Path $repoRoot "patches/$Project/$Rel.patch"
+
+if (-not (Test-Path $baseFile)) { throw "No baseline: $baseFile" }
+if (-not (Test-Path $workFile)) { throw "No working file: $workFile" }
+
+# Normalize CRLF->LF into temp files (BOM preserved, matching the .sh).
+$tmpBase = [System.IO.Path]::GetTempFileName()
+$tmpWork = [System.IO.Path]::GetTempFileName()
+$baseText = [System.IO.File]::ReadAllText($baseFile) -replace "`r`n", "`n" -replace "`r", "`n"
+$workText = [System.IO.File]::ReadAllText($workFile) -replace "`r`n", "`n" -replace "`r", "`n"
+$utf8 = New-Object System.Text.UTF8Encoding($false)
+[System.IO.File]::WriteAllText($tmpBase, $baseText, $utf8)
+[System.IO.File]::WriteAllText($tmpWork, $workText, $utf8)
+
+$raw = & git --no-pager -c core.safecrlf=false diff --no-color --no-index -U5 -- $tmpBase $tmpWork 2>$null
+
+Remove-Item $tmpBase, $tmpWork -ErrorAction SilentlyContinue
+
+if (-not $raw) { throw "git diff produced no output (files identical?)" }
+
+$a = "a/$Project/$Rel"
+$b = "b/$Project/$Rel"
+$out = foreach ($line in $raw) {
+    if ($line -like 'diff --git *') { "diff --git $a $b" }
+    elseif ($line -like '--- *')     { "--- $a" }
+    elseif ($line -like '+++ *')     { "+++ $b" }
+    else { $line }
+}
+
+New-Item -ItemType Directory -Force -Path (Split-Path -Parent $patchFile) | Out-Null
+[System.IO.File]::WriteAllText($patchFile, (($out -join "`n") + "`n"), $utf8)
+Write-Host "Wrote $patchFile"
diff --git a/scripts/tests/install-linux-prerequisites.sh b/scripts/tests/install-linux-prerequisites.sh
index 752dd396..e4cd628f 100644
--- a/scripts/tests/install-linux-prerequisites.sh
+++ b/scripts/tests/install-linux-prerequisites.sh
@@ -36,7 +36,7 @@ if [[ "${1:-}" == "tool" ]]; then
     printf '%s\n' "$*" >> "$HOME/dotnet-tool.log"
     cat > "$HOME/.dotnet/tools/ilspycmd" <<'TOOL'
 #!/usr/bin/env bash
-echo "ilspycmd: 10.1.1.8388"
+echo "ilspycmd: 11.0.0.9375"
 TOOL
     chmod +x "$HOME/.dotnet/tools/ilspycmd"
     exit 0
@@ -64,43 +64,39 @@ offer_install_missing <<< "Y"
 check_dotnet10
 [[ "$DOTNET_BIN" == "$HOME/.dotnet/dotnet" ]]
 
-ilspycmd_version_supported "10.1.0.8386"
-ilspycmd_version_supported "10.1.0.8387"
-ilspycmd_version_supported "10.1.1.0"
-ilspycmd_version_supported "10.1.1.8387"
-ilspycmd_version_supported "10.1.1.8388"
-if ilspycmd_version_supported "10.1.0.8385"; then
+ilspycmd_version_supported "11.0.0.9375"
+if ilspycmd_version_supported "11.0.0.9374"; then
     echo "version below the ilspycmd range passed validation" >&2
     exit 1
 fi
-if ilspycmd_version_supported "10.1.1.8389"; then
+if ilspycmd_version_supported "11.0.0.9376"; then
     echo "unvalidated ilspycmd revision passed validation" >&2
     exit 1
 fi
-if ilspycmd_version_supported "10.1.2.9000"; then
+if ilspycmd_version_supported "11.0.1.0"; then
     echo "future ilspycmd version passed validation" >&2
     exit 1
 fi
-if ilspycmd_version_supported "10.0.1.8346"; then
+if ilspycmd_version_supported "10.1.1.8388"; then
     echo "old ilspycmd line passed validation" >&2
     exit 1
 fi
-if ilspycmd_version_supported "10.2.0.1"; then
+if ilspycmd_version_supported "12.0.0.0"; then
     echo "unsupported ilspycmd version passed validation" >&2
     exit 1
 fi
-if ilspycmd_version_supported "10.0.0.8323-preview3"; then
+if ilspycmd_version_supported "11.0.0.9375-preview3"; then
     echo "preview ilspycmd version passed validation" >&2
     exit 1
 fi
-if ilspycmd_version_supported "10.1.1.8388-rc1"; then
+if ilspycmd_version_supported "11.0.0.9375-rc1"; then
     echo "prerelease ilspycmd version passed validation" >&2
     exit 1
 fi
 
 cat > "$HOME/.dotnet/tools/ilspycmd" <<'EOF'
 #!/usr/bin/env bash
-echo "ilspycmd: 10.1.0.8386"
+echo "ilspycmd: 11.0.0.9375"
 EOF
 chmod +x "$HOME/.dotnet/tools/ilspycmd"
 export PATH="$HOME/.dotnet/tools:$PATH"
@@ -110,7 +106,7 @@ check_ilspycmd
 rm -f "$HOME/.dotnet/tools/ilspycmd" "$HOME/dotnet-tool.log"
 hash -r
 install_ilspycmd
-grep -Fx "tool update -g ilspycmd --version 10.1.1.8388 --allow-downgrade" "$HOME/dotnet-tool.log" >/dev/null
+grep -Fx "tool update -g ilspycmd --version 11.0.0.9375 --allow-downgrade" "$HOME/dotnet-tool.log" >/dev/null
 check_ilspycmd
 
 echo "Linux prerequisite tests passed."
diff --git a/sources/VintagestoryApi/Config/OptimumAdaptiveRadiusController.cs b/sources/VintagestoryApi/Config/OptimumAdaptiveRadiusController.cs
index bcc19a99..d180ada9 100644
--- a/sources/VintagestoryApi/Config/OptimumAdaptiveRadiusController.cs
+++ b/sources/VintagestoryApi/Config/OptimumAdaptiveRadiusController.cs
@@ -87,7 +87,7 @@ public void Tick(int queueDepth, int maxRadius)
 
         // Hysteresis decision
         int current = Volatile.Read(ref _effectiveRadius);
-        int floor = OptimumConfig.AdaptiveRadiusFloor;
+        int floor = Math.Min(OptimumConfig.AdaptiveRadiusFloor, _configuredMax);
         int highThreshold = OptimumConfig.AdaptiveRadiusHighThreshold;
         int lowThreshold = OptimumConfig.AdaptiveRadiusLowThreshold;
 
diff --git a/sources/VintagestoryApi/Config/OptimumConfig.cs b/sources/VintagestoryApi/Config/OptimumConfig.cs
index 2554f038..3adaeb94 100644
--- a/sources/VintagestoryApi/Config/OptimumConfig.cs
+++ b/sources/VintagestoryApi/Config/OptimumConfig.cs
@@ -866,7 +866,7 @@ public static void Load()
             ChunkDeserializeParallelMinY = Math.Clamp(data.ChunkDeserializeParallelMinY, 2, 64);
             ShaderPreprocessParallel = data.ShaderPreprocessParallel;
             AdaptiveRadiusEnabled = data.AdaptiveRadius;
-            AdaptiveRadiusFloor = Math.Clamp(data.AdaptiveRadiusFloor, 1, 12);
+            AdaptiveRadiusFloor = Math.Clamp(data.AdaptiveRadiusFloor, 1, 48);
             AdaptiveRadiusHighThreshold = Math.Max(1, data.AdaptiveRadiusHighThreshold);
             AdaptiveRadiusLowThreshold = Math.Max(1, data.AdaptiveRadiusLowThreshold);
             LaunchTaskBudgetEnabled = data.LaunchTaskBudgetEnabled;
diff --git a/sources/VintagestoryApi/VintagestoryAPI.csproj b/sources/VintagestoryApi/VintagestoryAPI.csproj
index afbd3bc6..5a897928 100644
--- a/sources/VintagestoryApi/VintagestoryAPI.csproj
+++ b/sources/VintagestoryApi/VintagestoryAPI.csproj
@@ -34,6 +34,7 @@
     <Compile Remove="Common\Entity\EntityType.cs" />
     <Compile Remove="Common\Effect\AmbientModifier.cs" />
     <Compile Remove="Client\optimum-entity-render-batch.cs" />
+    <Compile Remove="Client\Model\Mesh\OptimumMeshPartPool.cs" />
     <Compile Remove="Config\AdaptiveWorkerController.cs" />
     <Compile Remove="Config\AdaptiveTessWorkerController.cs" />
     <Compile Remove="Config\OptimumAdaptiveRadiusController.cs" />
@@ -49,6 +50,10 @@
     <Compile Remove="Config\OptimumWorldgenSafetyGate.cs" />
     <Compile Remove="Config\optimum-worldgen-footprint-lease.cs" />
     <Compile Remove="Config\optimum-api-bridge.cs" />
+    <Compile Remove="Config\OptimumChunkVisibilityBfs.cs" />
+    <Compile Remove="Config\OptimumFrustumCullSimd.cs" />
+    <Compile Remove="Config\OptimumKometGuard.cs" />
+    <Compile Remove="Config\OptimumCompatibilityGuard.cs" />
   </ItemGroup>
 
   <ItemGroup>