diff --git a/.gitignore b/.gitignore
index 4fd589e..8b3ee77 100644
--- a/.gitignore
+++ b/.gitignore
@@ -409,3 +409,12 @@ FodyWeavers.xsd
 # JetBrains Rider
 *.sln.iml
 flatpak.bat
+
+# macOS build output (regenerated by build-app.sh)
+dist/
+
+# Serena tool working directory
+.serena/
+
+# Downloaded SDL2 native (fetched + verified by build-app.sh, not vendored)
+native/osx-arm64/*.dylib
diff --git a/App.axaml.cs b/App.axaml.cs
index 32f1deb..988a98d 100644
--- a/App.axaml.cs
+++ b/App.axaml.cs
@@ -209,7 +209,10 @@ public async Task CheckForAppUpdatesManually()
     private async Task CheckForUpdatesAndApplyAsync(bool isManualCheck = false)
     {
         string currentAppDirectory = AppDomain.CurrentDomain.BaseDirectory;
-        string updateCheckFilePath = Path.Combine(currentAppDirectory, UpdateCheckFileName);
+        // Update-check state is writable runtime data: keep it out of the (signed,
+        // immutable) app bundle on macOS. The executable-replacement logic below
+        // still uses currentAppDirectory.
+        string updateCheckFilePath = Path.Combine(AppPaths.DataDirectory, UpdateCheckFileName);
 
         UpdateCheckInfo updateCheckInfo = await LoadUpdateCheckInfo(updateCheckFilePath);
         string currentVersionString = updateCheckInfo.CurrentVersion;
diff --git a/GithubLauncher.csproj b/GithubLauncher.csproj
index d20861a..d6fc003 100644
--- a/GithubLauncher.csproj
+++ b/GithubLauncher.csproj
@@ -11,7 +11,7 @@
 		<Platforms>AnyCPU;x64</Platforms>
 		<Nullable>enable</Nullable>
 		<ImplicitUsings>enable</ImplicitUsings>
-		<RuntimeIdentifiers>win-x64;linux-x64;linux-arm64;osx-x64</RuntimeIdentifiers>
+		<RuntimeIdentifiers>win-x64;linux-x64;linux-arm64;osx-x64;osx-arm64</RuntimeIdentifiers>
 	</PropertyGroup>
 
 	<PropertyGroup Condition="$([MSBuild]::IsOSPlatform('Windows'))">
@@ -42,6 +42,24 @@
 		<AvaloniaResource Include="Assets/Icons/**" />
 	</ItemGroup>
 
+	<!-- ppy.SDL2-CS ships native SDL2 for osx-x64/linux/win but NOT osx-arm64.
+	     Bundle a self-contained official SDL2 (arm64) so the published app loads
+	     SDL2 with no external/Homebrew dependency. The .dylib is git-ignored and
+	     fetched + sha256-verified by build-app.sh (not vendored in the repo). -->
+	<ItemGroup Condition="'$(RuntimeIdentifier)' == 'osx-arm64'">
+		<None Include="native\osx-arm64\libSDL2.dylib">
+			<Link>libSDL2.dylib</Link>
+			<CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+			<CopyToPublishDirectory>PreserveNewest</CopyToPublishDirectory>
+		</None>
+	</ItemGroup>
+
+	<Target Name="EnsureSdl2Native" BeforeTargets="ResolveReferences"
+	        Condition="'$(RuntimeIdentifier)' == 'osx-arm64'">
+		<Error Condition="!Exists('native\osx-arm64\libSDL2.dylib')"
+		       Text="native/osx-arm64/libSDL2.dylib is missing. Run ./build-app.sh (it downloads and sha256-verifies the official SDL2). This native is intentionally not vendored in the repo." />
+	</Target>
+
 	<ItemGroup>
 		<ProjectReference Include="lib\GitHubLauncher.Core\GitHubLauncher.Core.csproj" />
 	</ItemGroup>
diff --git a/MainWindow.axaml.cs b/MainWindow.axaml.cs
index 243e94d..afbab0d 100644
--- a/MainWindow.axaml.cs
+++ b/MainWindow.axaml.cs
@@ -919,7 +919,7 @@ private void LoadCurrentVersion()
             try
             {
                 string currentAppDirectory = AppDomain.CurrentDomain.BaseDirectory;
-                string updateCheckFilePath = Path.Combine(currentAppDirectory, "update_check.json");
+                string updateCheckFilePath = Path.Combine(AppPaths.DataDirectory, "update_check.json");
 
                 if (File.Exists(updateCheckFilePath))
                 {
@@ -3565,7 +3565,7 @@ private async void ExportGames_Click(object sender, RoutedEventArgs e)
                 };
 
                 var options = new JsonSerializerOptions { WriteIndented = true };
-                var exportPath = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "apps_export.json");
+                var exportPath = Path.Combine(AppPaths.DataDirectory, "apps_export.json");
                 await File.WriteAllTextAsync(exportPath, JsonSerializer.Serialize(exportData, options));
 
                 await ShowMessageBoxAsync($"Apps exported to {exportPath}", "Export Complete");
@@ -3609,8 +3609,8 @@ private async void ValidateGames_Click(object sender, RoutedEventArgs e)
         }
         private async Task<List<GameInfo>> LoadGamesFromJsonAsync()
         {
-            var appsPath = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "apps.json");
-            var legacyPath = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "games.json");
+            var appsPath = Path.Combine(AppPaths.DataDirectory, "apps.json");
+            var legacyPath = Path.Combine(AppPaths.DataDirectory, "games.json");
             var sourcePath = File.Exists(appsPath) ? appsPath : legacyPath;
             if (!File.Exists(sourcePath)) return [];
 
@@ -3687,7 +3687,7 @@ private static object SerializeGame(GameInfo game)
         }
         private async Task SaveGamesToJsonAsync(List<GameInfo> appsToSave)
         {
-            var appsPath = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "apps.json");
+            var appsPath = Path.Combine(AppPaths.DataDirectory, "apps.json");
             var data = new
             {
                 apps = appsToSave.Select(SerializeGame).ToList()
@@ -4256,10 +4256,10 @@ private void RefreshAppCatalog_Click(object sender, RoutedEventArgs e)
 
         // App Catalog
         private static readonly string AppCatalogCachePath = Path.Combine(
-            AppDomain.CurrentDomain.BaseDirectory, "app_catalog_cache.json");
+            AppPaths.DataDirectory, "app_catalog_cache.json");
 
         private static readonly string AppCatalogVersionPath = Path.Combine(
-            AppDomain.CurrentDomain.BaseDirectory, "app_catalog_version.txt");
+            AppPaths.DataDirectory, "app_catalog_version.txt");
 
         private async Task LoadAppCatalogAsync(bool forceRefresh)
         {
diff --git a/Services/AppPaths.cs b/Services/AppPaths.cs
new file mode 100644
index 0000000..3a62a57
--- /dev/null
+++ b/Services/AppPaths.cs
@@ -0,0 +1,41 @@
+using System;
+using System.IO;
+using System.Runtime.InteropServices;
+
+namespace GithubLauncher
+{
+    /// <summary>
+    /// Resolves where the launcher stores writable data.
+    ///
+    /// On macOS the launcher ships as a signed <c>.app</c> bundle whose contents
+    /// must stay immutable — writing next to the executable (inside
+    /// <c>Contents/MacOS</c>) invalidates the code signature and prevents the app
+    /// from living in a read-only location such as <c>/Applications</c>. So on
+    /// macOS user data lives in <c>~/Library/Application Support/GithubLauncher</c>.
+    ///
+    /// On Windows/Linux behavior is unchanged: data stays next to the executable
+    /// (portable app layout).
+    /// </summary>
+    public static class AppPaths
+    {
+        /// <summary>Executable location. Use only for self-update; never for user data on macOS.</summary>
+        public static string AppDirectory => AppContext.BaseDirectory;
+
+        private static readonly Lazy<string> _dataDirectory = new(() =>
+        {
+            if (RuntimeInformation.IsOSPlatform(OSPlatform.OSX))
+            {
+                string appSupport = Path.Combine(
+                    Environment.GetFolderPath(Environment.SpecialFolder.UserProfile),
+                    "Library", "Application Support", "GithubLauncher");
+                Directory.CreateDirectory(appSupport);
+                return appSupport;
+            }
+
+            return AppContext.BaseDirectory;
+        });
+
+        /// <summary>Writable data root (settings, app registry, caches, installed apps). Created on first access.</summary>
+        public static string DataDirectory => _dataDirectory.Value;
+    }
+}
diff --git a/Services/AppSettings.cs b/Services/AppSettings.cs
index 7f2fc23..a394f12 100644
--- a/Services/AppSettings.cs
+++ b/Services/AppSettings.cs
@@ -36,7 +36,7 @@ public class AppSettings
         public string AppListRepository { get; set; } = "SirDiabo/GHLAppList";
         public string AppListCachedVersion { get; set; } = string.Empty;
         private static readonly string SettingsPath = Path.Combine(
-            AppDomain.CurrentDomain.BaseDirectory,
+            AppPaths.DataDirectory,
             "settings.json"
         );
 
diff --git a/Services/CLIHandler.cs b/Services/CLIHandler.cs
index e2bddb1..699826e 100644
--- a/Services/CLIHandler.cs
+++ b/Services/CLIHandler.cs
@@ -164,7 +164,7 @@ private void LoadVersion()
             try
             {
                 string currentAppDirectory = AppDomain.CurrentDomain.BaseDirectory;
-                string updateCheckFilePath = Path.Combine(currentAppDirectory, "update_check.json");
+                string updateCheckFilePath = Path.Combine(AppPaths.DataDirectory, "update_check.json");
 
                 if (File.Exists(updateCheckFilePath))
                 {
diff --git a/Services/GameManager.cs b/Services/GameManager.cs
index 3301aa0..5b2abea 100644
--- a/Services/GameManager.cs
+++ b/Services/GameManager.cs
@@ -58,11 +58,11 @@ public GameManager()
 
             _appsFolder = !string.IsNullOrEmpty(_settings?.AppsPath)
                 ? _settings.AppsPath
-                : Path.Combine(AppDomain.CurrentDomain.BaseDirectory, Profile.DefaultInstallFolderName);
+                : Path.Combine(AppPaths.DataDirectory, Profile.DefaultInstallFolderName);
 
-            _cacheFolder = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "Cache");
-            _appsConfigPath = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "apps.json");
-            _legacyGamesConfigPath = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "games.json");
+            _cacheFolder = Path.Combine(AppPaths.DataDirectory, "Cache");
+            _appsConfigPath = Path.Combine(AppPaths.DataDirectory, "apps.json");
+            _legacyGamesConfigPath = Path.Combine(AppPaths.DataDirectory, "games.json");
 
             try
             {
@@ -419,7 +419,7 @@ public async Task UpdateGamesFolderAsync(string newPath)
                 }
                 else
                 {
-                    targetPath = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, Profile.DefaultInstallFolderName);
+                    targetPath = Path.Combine(AppPaths.DataDirectory, Profile.DefaultInstallFolderName);
                     Directory.CreateDirectory(targetPath);
                 }
 
@@ -435,7 +435,7 @@ public async Task UpdateGamesFolderAsync(string newPath)
             catch (Exception ex)
             {
                 System.Diagnostics.Debug.WriteLine($"Error updating apps folder: {ex.Message}");
-                _appsFolder = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, Profile.DefaultInstallFolderName);
+                _appsFolder = Path.Combine(AppPaths.DataDirectory, Profile.DefaultInstallFolderName);
                 Directory.CreateDirectory(_appsFolder);
                 throw;
             }
diff --git a/build-app.sh b/build-app.sh
new file mode 100755
index 0000000..4c0e24e
--- /dev/null
+++ b/build-app.sh
@@ -0,0 +1,106 @@
+#!/usr/bin/env bash
+#
+# Build a native arm64 macOS .app bundle for Github Launcher.
+# Self-contained: bundles the .NET runtime and the official SDL2 (arm64).
+# No Homebrew or other external runtime dependencies.
+#
+# ppy.SDL2-CS ships no arm64-macOS native, so this script downloads the official
+# SDL2 release, verifies its sha256, and thins it to arm64 before publishing.
+#
+set -euo pipefail
+
+cd "$(dirname "$0")"
+
+RID="osx-arm64"
+CONFIG="Release"
+TFM="net9.0"
+APP_NAME="Github Launcher"
+APP="dist/${APP_NAME}.app"
+PUBLISH="bin/${CONFIG}/${TFM}/${RID}/publish"
+
+# Official SDL2 release (universal, self-contained: links only system frameworks).
+SDL2_VERSION="2.32.10"
+SDL2_DMG_URL="https://github.com/libsdl-org/SDL/releases/download/release-${SDL2_VERSION}/SDL2-${SDL2_VERSION}.dmg"
+SDL2_DMG_SHA256="4a7ac31640d70214e848f994be8a12849c0f97918a7e6c2e27a40036166d1a7f"
+SDL2_NATIVE="native/osx-arm64/libSDL2.dylib"
+
+echo ">> Ensuring submodule is present..."
+git submodule update --init --recursive
+
+if [ -f "$SDL2_NATIVE" ]; then
+  echo ">> SDL2 native already present ($SDL2_NATIVE)"
+else
+  echo ">> Fetching official SDL2 ${SDL2_VERSION}..."
+  TMP="$(mktemp -d)"
+  curl -fsSL -o "$TMP/sdl2.dmg" "$SDL2_DMG_URL"
+  echo "${SDL2_DMG_SHA256}  ${TMP}/sdl2.dmg" | shasum -a 256 -c -
+  MNT="$(hdiutil attach "$TMP/sdl2.dmg" -nobrowse -readonly | grep -o '/Volumes/.*' | head -1)"
+  mkdir -p "$(dirname "$SDL2_NATIVE")"
+  # Thin the universal framework binary to arm64 for this RID.
+  lipo "$MNT/SDL2.framework/Versions/A/SDL2" -thin arm64 -output "$SDL2_NATIVE"
+  hdiutil detach "$MNT" >/dev/null
+  rm -rf "$TMP"
+  echo ">> SDL2 native ready: $SDL2_NATIVE ($(file -b "$SDL2_NATIVE"))"
+fi
+
+echo ">> Publishing ${RID} (self-contained)..."
+rm -rf "bin/${CONFIG}/${TFM}/${RID}"
+dotnet publish GithubLauncher.csproj -c "$CONFIG" -r "$RID" --self-contained true
+
+echo ">> Assembling ${APP}..."
+rm -rf "$APP"
+mkdir -p "$APP/Contents/MacOS" "$APP/Contents/Resources"
+cp -R "$PUBLISH/." "$APP/Contents/MacOS/"
+
+echo ">> Generating icon..."
+ICONSET="$(mktemp -d)/AppIcon.iconset"
+mkdir -p "$ICONSET"
+sips -s format png icon.ico --out "$ICONSET/base.png" >/dev/null
+for sz in 16 32 128 256 512; do
+  sips -z "$sz" "$sz" "$ICONSET/base.png" --out "$ICONSET/icon_${sz}x${sz}.png" >/dev/null
+  dbl=$((sz * 2))
+  sips -z "$dbl" "$dbl" "$ICONSET/base.png" --out "$ICONSET/icon_${sz}x${sz}@2x.png" >/dev/null
+done
+rm "$ICONSET/base.png"
+iconutil -c icns "$ICONSET" -o "$APP/Contents/Resources/AppIcon.icns"
+
+echo ">> Writing Info.plist..."
+cat > "$APP/Contents/Info.plist" <<'PLIST'
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>CFBundleName</key>
+	<string>Github Launcher</string>
+	<key>CFBundleDisplayName</key>
+	<string>Github Launcher</string>
+	<key>CFBundleIdentifier</key>
+	<string>com.sirdiabo.githublauncher</string>
+	<key>CFBundleVersion</key>
+	<string>1.0.0.0</string>
+	<key>CFBundleShortVersionString</key>
+	<string>1.0.0</string>
+	<key>CFBundlePackageType</key>
+	<string>APPL</string>
+	<key>CFBundleExecutable</key>
+	<string>GithubLauncher</string>
+	<key>CFBundleIconFile</key>
+	<string>AppIcon</string>
+	<key>LSMinimumSystemVersion</key>
+	<string>11.0</string>
+	<key>NSHighResolutionCapable</key>
+	<true/>
+	<key>LSApplicationCategoryType</key>
+	<string>public.app-category.games</string>
+	<key>NSPrincipalClass</key>
+	<string>NSApplication</string>
+</dict>
+</plist>
+PLIST
+
+echo ">> Code signing (ad-hoc)..."
+chmod +x "$APP/Contents/MacOS/GithubLauncher"
+codesign --force --deep --sign - "$APP"
+codesign --verify --strict "$APP"
+
+echo ">> Done: $APP"