pack: add Almost Unified 1.4.2 + bump to 0.12.0

Preemptive insurance against duplicate-item proliferation when more
metals-producing mods are added (e.g. when Power Grid lands, or any
future Mekanism/Thermal/etc. addition). Today's pack only has TFMG as
the metals provider so AU is largely a no-op now, but ships with sane
default tag preferences that activate automatically as duplicates appear.

Tiny mod (~290 KB jar), client-optional/server-required per Modrinth.

launcher/App.axaml.cs

@@ -1,6 +1,7 @@
 using Avalonia;
 using Avalonia.Controls.ApplicationLifetimes;
 using Avalonia.Markup.Xaml;
+using ModpackLauncher.Services;
 
 namespace ModpackLauncher;
 
@@ -13,6 +14,11 @@ public partial class App : Application
 
     public override void OnFrameworkInitializationCompleted()
     {
+        // Clean up any .old launcher left behind by a self-update on a prior run.
+        // Best-effort: if the previous process hasn't fully released the handle yet
+        // we just retry on the next startup.
+        SelfUpdateService.CleanupAfterUpdate();
+
         if (ApplicationLifetime is IClassicDesktopStyleApplicationLifetime desktop)
         {
             desktop.MainWindow = new MainWindow();

launcher/MainWindow.axaml

@@ -259,7 +259,7 @@
                                            Foreground="#E8DFC8" FontSize="13" TextWrapping="Wrap"
                                            Text="A newer launcher is available." />
                                 <Button Grid.Column="2" Name="UpdateBannerDownloadButton"
-                                        Classes="secondary" Content="Download"
+                                        Classes="secondary" Content="Install update"
                                         Click="OnUpdateBannerDownloadClick" />
                             </Grid>
                         </Border>

launcher/MainWindow.axaml.cs

@@ -128,22 +128,57 @@ public partial class MainWindow : Window
         if (current >= advertised) return;
 
         UpdateBannerText.Text = $"A newer launcher (v{advertised}) is available -- you're on v{current.Major}.{current.Minor}.{current.Build}.";
-        UpdateBannerDownloadButton.Tag = manifest.LauncherUrl ?? "https://sijbers.uk/pack/BrassAndSigil-Launcher.exe";
+        UpdateBannerDownloadButton.Tag = manifest.LauncherUrl ?? "https://bns.sijbers.uk/launcher/BrassAndSigil-Launcher.exe";
         UpdateBanner.IsVisible = true;
         AppendLog($"[update] Newer launcher available: v{advertised} (running v{current})");
     }
 
-    private void OnUpdateBannerDownloadClick(object? sender, RoutedEventArgs e)
+    private async void OnUpdateBannerDownloadClick(object? sender, RoutedEventArgs e)
     {
-        var url = UpdateBannerDownloadButton.Tag as string
+        var url = UpdateBannerDownloadButton.Tag as string;
-                  ?? "https://sijbers.uk/pack/BrassAndSigil-Launcher.exe";
+        if (string.IsNullOrEmpty(url))
+        {
+            AppendLog("[update] No download URL configured in manifest.");
+            return;
+        }
+
+        // First click: try in-place self-update. On failure (network blip, write-protected
+        // dir, antivirus blocking), fall back to opening the browser so the user can still
+        // grab the new exe manually.
+        UpdateBannerDownloadButton.IsEnabled = false;
+        var originalLabel = UpdateBannerDownloadButton.Content as string ?? "Install update";
+        UpdateBannerDownloadButton.Content = "Updating...";
+
+        try
+        {
+            var svc = new ModpackLauncher.Services.SelfUpdateService();
+            var progress = new Progress<(long bytes, long? total)>(p =>
+            {
+                var mb = p.bytes / 1024.0 / 1024.0;
+                UpdateBannerDownloadButton.Content = p.total.HasValue
+                    ? $"{(double)p.bytes * 100 / p.total.Value:F0}%"
+                    : $"{mb:F1} MB";
+            });
+            await svc.DownloadAndInstallAsync(url, progress, AppendLog);
+            // If the method returns, it means it didn't exit -- that shouldn't normally
+            // happen, but reset the UI just in case.
+            UpdateBannerDownloadButton.Content = originalLabel;
+            UpdateBannerDownloadButton.IsEnabled = true;
+        }
+        catch (Exception ex)
+        {
+            AppendLog($"[update] Auto-update failed: {ex.Message}");
+            AppendLog("[update] Opening browser as fallback...");
             try
             {
                 Process.Start(new ProcessStartInfo { FileName = url, UseShellExecute = true });
             }
-        catch (Exception ex)
+            catch (Exception ex2)
             {
-            AppendLog($"[update] Couldn't open browser: {ex.Message}");
+                AppendLog($"[update] Browser fallback also failed: {ex2.Message}");
+            }
+            UpdateBannerDownloadButton.Content = originalLabel;
+            UpdateBannerDownloadButton.IsEnabled = true;
         }
     }
 

launcher/Models/Manifest.cs

@@ -95,6 +95,15 @@ public sealed class ManifestFile
 
     [JsonPropertyName("size")]
     public long? Size { get; set; }
+
+    /// <summary>
+    /// "both" (default), "client", or "server". The launcher skips files
+    /// marked "server"; the server-tool skips files marked "client".
+    /// Null/missing/unknown = treated as "both" so manifests pre-dating
+    /// this field stay fully compatible.
+    /// </summary>
+    [JsonPropertyName("side")]
+    public string? Side { get; set; }
 }
 
 public sealed class PackVersionRecord

launcher/ModpackLauncher.csproj

@@ -10,7 +10,7 @@
     <AvaloniaUseCompiledBindingsByDefault>true</AvaloniaUseCompiledBindingsByDefault>
     <RootNamespace>ModpackLauncher</RootNamespace>
     <AssemblyName>ModpackLauncher</AssemblyName>
-    <Version>0.4.6</Version>
+    <Version>0.4.8</Version>
     <ApplicationIcon Condition="Exists('Assets\icon.ico')">Assets\icon.ico</ApplicationIcon>
 
     <!-- Single-file self-contained publish defaults (Windows-only now due to WebView2) -->

launcher/Services/ManifestSyncService.cs

@@ -66,6 +66,7 @@ public sealed class ManifestSyncService
         var missing = new System.Collections.Generic.List<ManifestFile>();
         foreach (var file in manifest.Files)
         {
+            if (IsServerOnly(file)) continue;   // never expected on disk client-side
             var dest = Path.Combine(installDir, file.Path);
             if (!File.Exists(dest)) missing.Add(file);
         }
@@ -113,6 +114,19 @@ public sealed class ManifestSyncService
             $"Pack: {manifest.Name ?? "modpack"} v{manifest.Version ?? "?"} (local: {local?.Version ?? "none"})"
         ));
 
+        // Drop server-only files before computing wanted/download sets. Doing
+        // it once here means the rest of the sync (prune + download) doesn't
+        // need to know about sides. Unknown/missing/'both' = include on client.
+        var serverOnlyCount = manifest.Files.Count(f => IsServerOnly(f));
+        if (serverOnlyCount > 0)
+        {
+            manifest.Files = manifest.Files.Where(f => !IsServerOnly(f)).ToList();
+            progress.Report(new ProgressReport(
+                ProgressKind.Log,
+                $"Skipping {serverOnlyCount} server-only file(s) declared in manifest."
+            ));
+        }
+
         var wantedPaths = new HashSet<string>(
             manifest.Files.Select(f => NormalizePath(f.Path)),
             StringComparer.OrdinalIgnoreCase
@@ -249,4 +263,12 @@ public sealed class ManifestSyncService
     }
 
     private static string NormalizePath(string p) => p.Replace('\\', '/').TrimStart('/');
+
+    /// <summary>
+    /// True if this manifest file is tagged as server-only and therefore
+    /// should not be installed on the client. Unknown/null/'both' = false
+    /// (always include) so manifests pre-dating the field still install.
+    /// </summary>
+    private static bool IsServerOnly(ManifestFile f)
+        => string.Equals(f.Side, "server", StringComparison.OrdinalIgnoreCase);
 }

launcher/Services/SelfUpdateService.cs

@@ -0,0 +1,138 @@
+using System;
+using System.Diagnostics;
+using System.IO;
+using System.Net.Http;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace ModpackLauncher.Services;
+
+/// <summary>
+/// In-place launcher self-update. Pattern matches Chrome/VS Code/Discord:
+///   1. Download new exe to "<current>.new"
+///   2. Rename running exe to "<current>.old" (Windows allows MoveFile on a running exe)
+///   3. Rename ".new" to the canonical name
+///   4. Process.Start the new exe with our args
+///   5. Exit -- the OS releases the .old file once the old process is gone
+///   6. Next launcher start deletes any leftover .old via CleanupAfterUpdate()
+///
+/// Fails loudly (throws) on any step. Caller falls back to browser-open download.
+/// </summary>
+public sealed class SelfUpdateService
+{
+    private static readonly HttpClient _http = new()
+    {
+        Timeout = TimeSpan.FromMinutes(5),
+        DefaultRequestVersion = new Version(2, 0),
+    };
+
+    public static string CurrentExePath =>
+        Environment.ProcessPath
+        ?? throw new InvalidOperationException("Environment.ProcessPath was null (self-update needs a real exe path).");
+
+    public static string OldExePath => CurrentExePath + ".old";
+    public static string NewExePath => CurrentExePath + ".new";
+
+    /// <summary>
+    /// Delete any leftover .old file from a prior self-update. Safe to call on every startup;
+    /// quietly retries next start if the file is still locked (rare timing edge case).
+    /// </summary>
+    public static void CleanupAfterUpdate(Action<string>? log = null)
+    {
+        var old = OldExePath;
+        if (!File.Exists(old)) return;
+        try
+        {
+            File.Delete(old);
+            log?.Invoke($"[update] Removed previous launcher backup: {Path.GetFileName(old)}");
+        }
+        catch (Exception ex)
+        {
+            // The old process may still be releasing the file handle. Not fatal --
+            // we'll retry next start. Worst case the .old file sits there harmlessly.
+            log?.Invoke($"[update] Couldn't remove {Path.GetFileName(old)} yet ({ex.GetType().Name}); will retry next start.");
+        }
+    }
+
+    /// <summary>
+    /// Download the new launcher, swap it in, restart with the same command line, and exit.
+    /// Returns only on failure (i.e. throws) -- on success the current process exits.
+    /// </summary>
+    public async Task DownloadAndInstallAsync(
+        string downloadUrl,
+        IProgress<(long bytesReceived, long? totalBytes)>? progress = null,
+        Action<string>? log = null,
+        CancellationToken ct = default)
+    {
+        var curPath = CurrentExePath;
+        var newPath = NewExePath;
+        var oldPath = OldExePath;
+
+        log?.Invoke($"[update] Downloading {downloadUrl}");
+
+        // 1. Download to .new, replacing any stale partial from a failed prior attempt
+        if (File.Exists(newPath)) File.Delete(newPath);
+
+        using (var resp = await _http.GetAsync(downloadUrl, HttpCompletionOption.ResponseHeadersRead, ct))
+        {
+            resp.EnsureSuccessStatusCode();
+            var total = resp.Content.Headers.ContentLength;
+            await using var src = await resp.Content.ReadAsStreamAsync(ct);
+            await using var dst = new FileStream(newPath, FileMode.CreateNew, FileAccess.Write, FileShare.None);
+
+            var buffer = new byte[81920];
+            long received = 0;
+            int read;
+            while ((read = await src.ReadAsync(buffer, ct)) > 0)
+            {
+                await dst.WriteAsync(buffer.AsMemory(0, read), ct);
+                received += read;
+                progress?.Report((received, total));
+            }
+            log?.Invoke($"[update] Downloaded {received:N0} bytes");
+        }
+
+        // Sanity: refuse to swap in something laughably small (a captive portal
+        // intercepted us, or the server returned an error body as 200 OK).
+        var fi = new FileInfo(newPath);
+        if (fi.Length < 1_000_000)
+        {
+            File.Delete(newPath);
+            throw new InvalidDataException($"Downloaded launcher is only {fi.Length:N0} bytes -- almost certainly not the real binary.");
+        }
+
+        // 2. Move running exe to .old (this works while we're executing — NTFS resolves
+        //    running processes by handle, not by path).
+        if (File.Exists(oldPath)) File.Delete(oldPath);
+        File.Move(curPath, oldPath);
+        log?.Invoke($"[update] Backed up current launcher to {Path.GetFileName(oldPath)}");
+
+        // 3. Move new exe into the canonical slot
+        File.Move(newPath, curPath);
+        log?.Invoke($"[update] New launcher staged at {Path.GetFileName(curPath)}");
+
+        // 4. Build the restart command. Pass through any args the current process was
+        //    launched with (e.g. URI handler args from a future deep-link integration),
+        //    skipping argv[0] which is the exe itself.
+        var args = Environment.GetCommandLineArgs();
+        var psi = new ProcessStartInfo
+        {
+            FileName        = curPath,
+            UseShellExecute = false,
+            WorkingDirectory = Path.GetDirectoryName(curPath) ?? Environment.CurrentDirectory,
+        };
+        for (int i = 1; i < args.Length; i++) psi.ArgumentList.Add(args[i]);
+
+        log?.Invoke("[update] Restarting with the new launcher...");
+        Process.Start(psi);
+
+        // Tiny grace period so the spawn has actually entered the kernel before we
+        // pull our pid out from under it. 100 ms is more than enough.
+        await Task.Delay(100, CancellationToken.None);
+
+        // Hard exit. We don't go through Avalonia shutdown -- Application.Lifetime.Exit()
+        // can hang on window close handlers, and we DO want to release our exe handle
+        // promptly so the new process's CleanupAfterUpdate() can delete our .old file.
+        Environment.Exit(0);
+    }
+}

pack/pack.lock.json

@@ -1,13 +1,13 @@
 {
   "$schema": "Brass-and-Sigil pack.lock.json - generated, do not edit by hand unless you know what you are doing",
   "name": "Brass and Sigil",
-    "version":  "0.9.3",
+  "version": "0.12.0",
   "minecraft": "1.21.1",
   "loader": {
     "type": "neoforge",
     "version": "21.1.228"
   },
-    "lockedAt":  "2026-05-04T14:22:58.7131203+01:00",
+  "lockedAt": "2026-05-04T13:22:58.7131203+00:00",
   "mods": [
     {
       "source": "modrinth",
@@ -17,7 +17,8 @@
       "path": "mods/create-1.21.1-6.0.10.jar",
       "url": "https://cdn.modrinth.com/data/LNytGWDc/versions/UjX6dr61/create-1.21.1-6.0.10.jar",
       "sha1": "0e97e49837bed766e6f28a4c95b04885d6acc353",
-                     "size":  19123767
+      "size": 19123767,
+      "side": "both"
     },
     {
       "source": "modrinth",
@@ -27,7 +28,8 @@
       "path": "mods/create-aeronautics-bundled-1.21.1-1.2.1.jar",
       "url": "https://cdn.modrinth.com/data/oWaK0Q19/versions/YhZLrAFC/create-aeronautics-bundled-1.21.1-1.2.1.jar",
       "sha1": "fdf1ae69e8b6437e0196b3a35dd2325aa904aba9",
-                     "size":  33030286
+      "size": 33030286,
+      "side": "both"
     },
     {
       "source": "modrinth",
@@ -37,7 +39,8 @@
       "path": "mods/sable-neoforge-1.21.1-1.2.2.jar",
       "url": "https://cdn.modrinth.com/data/T9PomCSv/versions/3FMsUjO4/sable-neoforge-1.21.1-1.2.2.jar",
       "sha1": "c5ecd3fcf60a31d84112c708abe29e341b2d1b73",
-                     "size":  12719293
+      "size": 12719293,
+      "side": "both"
     },
     {
       "source": "modrinth",
@@ -47,7 +50,8 @@
       "path": "mods/createbigcannons-5.11.3+mc.1.21.1.jar",
       "url": "https://cdn.modrinth.com/data/GWp4jCJj/versions/bsGaXKEd/createbigcannons-5.11.3%2Bmc.1.21.1.jar",
       "sha1": "8b61fa850e260bdeb5d360576123f98c260afa50",
-                     "size":  3715787
+      "size": 3715787,
+      "side": "both"
     },
     {
       "source": "modrinth",
@@ -57,7 +61,8 @@
       "path": "mods/tfmg-1.2.0.jar",
       "url": "https://cdn.modrinth.com/data/USgVjXsk/versions/uDi14nbt/tfmg-1.2.0.jar",
       "sha1": "b520f3687f60a69eb265ff5b9a16759b9e124103",
-                     "size":  4924243
+      "size": 4924243,
+      "side": "both"
     },
     {
       "source": "modrinth",
@@ -67,7 +72,8 @@
       "path": "mods/DistantHorizons-3.0.2-b-1.21.1-fabric-neoforge.jar",
       "url": "https://cdn.modrinth.com/data/uCdwusMi/versions/KkaaQtTD/DistantHorizons-3.0.2-b-1.21.1-fabric-neoforge.jar",
       "sha1": "1ff0a8920e52add541471f7b32d0d389997145ba",
-                     "size":  30019727
+      "size": 30019727,
+      "side": "both"
     },
     {
       "source": "modrinth",
@@ -77,7 +83,8 @@
       "path": "mods/sodium-neoforge-0.6.13+mc1.21.1.jar",
       "url": "https://cdn.modrinth.com/data/AANobbMI/versions/Pb3OXVqC/sodium-neoforge-0.6.13%2Bmc1.21.1.jar",
       "sha1": "38af70fa4dc4b2aaac636e92fdba3bedd5a025e1",
-                     "size":  1162994
+      "size": 1162994,
+      "side": "client"
     },
     {
       "source": "modrinth",
@@ -87,7 +94,8 @@
       "path": "mods/iris-neoforge-1.8.12+mc1.21.1.jar",
       "url": "https://cdn.modrinth.com/data/YL57xq9U/versions/t3ruzodq/iris-neoforge-1.8.12%2Bmc1.21.1.jar",
       "sha1": "a3e6355915c7d3b2bc392724795113e51d289378",
-                     "size":  2438548
+      "size": 2438548,
+      "side": "client"
     },
     {
       "source": "modrinth",
@@ -97,7 +105,8 @@
       "path": "mods/modernfix-neoforge-5.27.4+mc1.21.1.jar",
       "url": "https://cdn.modrinth.com/data/nmDcB62a/versions/6U8JVjdw/modernfix-neoforge-5.27.4%2Bmc1.21.1.jar",
       "sha1": "2f39363f0d6d5a5ccc2a9e0f50ad3385611c3cb7",
-                     "size":  562051
+      "size": 562051,
+      "side": "both"
     },
     {
       "source": "modrinth",
@@ -107,7 +116,8 @@
       "path": "mods/ferritecore-7.0.3-neoforge.jar",
       "url": "https://cdn.modrinth.com/data/uXXizFIs/versions/x7kQWVju/ferritecore-7.0.3-neoforge.jar",
       "sha1": "9563692efb708b6b568df27a01ec52f6311928ef",
-                     "size":  121559
+      "size": 121559,
+      "side": "both"
     },
     {
       "source": "modrinth",
@@ -117,7 +127,8 @@
       "path": "mods/architectury-13.0.8-neoforge.jar",
       "url": "https://cdn.modrinth.com/data/lhGA9TYQ/versions/ZxYGwlk0/architectury-13.0.8-neoforge.jar",
       "sha1": "6ca11d3cc136bf69bb8f4d56982481eb85b5100b",
-                     "size":  584004
+      "size": 584004,
+      "side": "both"
     },
     {
       "source": "modrinth",
@@ -127,7 +138,8 @@
       "path": "mods/rhino-2101.2.7-build.81.jar",
       "url": "https://cdn.modrinth.com/data/sk9knFPE/versions/ZdLtebKH/rhino-2101.2.7-build.81.jar",
       "sha1": "480235a9f7749f68ce6fec3b9c3cac3428b92a4a",
-                     "size":  882033
+      "size": 882033,
+      "side": "both"
     },
     {
       "source": "modrinth",
@@ -137,7 +149,8 @@
       "path": "mods/ritchiesprojectilelib-2.1.2+mc.1.21.1-neoforge.jar",
       "url": "https://cdn.modrinth.com/data/B3pb093D/versions/hZ6B2Z0x/ritchiesprojectilelib-2.1.2%2Bmc.1.21.1-neoforge.jar",
       "sha1": "ec2e4996f8bee8714173e603e379fef8a6901765",
-                     "size":  76369
+      "size": 76369,
+      "side": "both"
     },
     {
       "source": "modrinth",
@@ -147,7 +160,8 @@
       "path": "mods/kubejs-neoforge-2101.7.2-build.363.jar",
       "url": "https://cdn.modrinth.com/data/umyGl7zF/versions/Fe9CjPws/kubejs-neoforge-2101.7.2-build.363.jar",
       "sha1": "d4e88254e8c26687d4c6aeb4dfa9c2ad70f260a2",
-                     "size":  2270442
+      "size": 2270442,
+      "side": "both"
     },
     {
       "source": "modrinth",
@@ -157,7 +171,8 @@
       "path": "mods/jei-1.21.1-neoforge-19.27.0.340.jar",
       "url": "https://cdn.modrinth.com/data/u6dRKJwZ/versions/YAcQ6elZ/jei-1.21.1-neoforge-19.27.0.340.jar",
       "sha1": "27d0d85e7e32e926fc3664ab6815df5cdabb7941",
-                     "size":  1529391
+      "size": 1529391,
+      "side": "both"
     },
     {
       "source": "modrinth",
@@ -167,7 +182,8 @@
       "path": "mods/Jade-1.21.1-NeoForge-15.10.5.jar",
       "url": "https://cdn.modrinth.com/data/nvQzSEkH/versions/yd8FKCmx/Jade-1.21.1-NeoForge-15.10.5.jar",
       "sha1": "d5bf134b3dbde9f5258666823900e21341dc0a50",
-                     "size":  725742
+      "size": 725742,
+      "side": "both"
     },
     {
       "source": "modrinth",
@@ -177,7 +193,8 @@
       "path": "mods/Chunky-NeoForge-1.4.23.jar",
       "url": "https://cdn.modrinth.com/data/fALzjamp/versions/LuFhm4eU/Chunky-NeoForge-1.4.23.jar",
       "sha1": "ab0c74743a653020fe2dfc4986b43e893947f3e9",
-                     "size":  340572
+      "size": 340572,
+      "side": "both"
     },
     {
       "source": "curseforge",
@@ -187,7 +204,8 @@
       "path": "mods/ftb-library-neoforge-2101.1.31.jar",
       "url": "https://mediafilez.forgecdn.net/files/7746/959/ftb-library-neoforge-2101.1.31.jar",
       "sha1": "686d4e784c28c14f7760cc22b2de6a8573b56b74",
-                     "size":  1411181
+      "size": 1411181,
+      "side": "both"
     },
     {
       "source": "curseforge",
@@ -197,7 +215,8 @@
       "path": "mods/ftb-teams-neoforge-2101.1.9.jar",
       "url": "https://mediafilez.forgecdn.net/files/7369/21/ftb-teams-neoforge-2101.1.9.jar",
       "sha1": "328e04bf1a445870aacea8fe7637670f84272a8f",
-                     "size":  291847
+      "size": 291847,
+      "side": "both"
     },
     {
       "source": "curseforge",
@@ -207,7 +226,8 @@
       "path": "mods/ftb-chunks-neoforge-2101.1.14.jar",
       "url": "https://mediafilez.forgecdn.net/files/7608/681/ftb-chunks-neoforge-2101.1.14.jar",
       "sha1": "908b63b11d0e00ae6c9557d3fe6440bdbcf21bb7",
-                     "size":  642340
+      "size": 642340,
+      "side": "both"
     },
     {
       "source": "modrinth",
@@ -217,7 +237,8 @@
       "path": "mods/ars_nouveau-1.21.1-5.11.3.jar",
       "url": "https://cdn.modrinth.com/data/TKB6INcv/versions/BmGGrC9A/ars_nouveau-1.21.1-5.11.3.jar",
       "sha1": "0af12dd7fda63a4261ceb302c9bb57fc235641c6",
-                     "size":  20689115
+      "size": 20689115,
+      "side": "both"
     },
     {
       "source": "modrinth",
@@ -227,7 +248,8 @@
       "path": "mods/Terralith_1.21.x_v2.5.8.jar",
       "url": "https://cdn.modrinth.com/data/8oi3bsk5/versions/MuJMtPGQ/Terralith_1.21.x_v2.5.8.jar",
       "sha1": "bee0cfb1a8cd4bf3d96bccea224fb45d74de9085",
-                     "size":  3115385
+      "size": 3115385,
+      "side": "both"
     },
     {
       "source": "modrinth",
@@ -237,7 +259,8 @@
       "path": "mods/YungsBetterStrongholds-1.21.1-NeoForge-5.1.3.jar",
       "url": "https://cdn.modrinth.com/data/kidLKymU/versions/8U0dIfSM/YungsBetterStrongholds-1.21.1-NeoForge-5.1.3.jar",
       "sha1": "5d06a5850af7c577612d4592706a8e156bbe1cbf",
-                     "size":  461244
+      "size": 461244,
+      "side": "server"
     },
     {
       "source": "modrinth",
@@ -247,7 +270,8 @@
       "path": "mods/lithostitched-1.7.2-neoforge-21.1.jar",
       "url": "https://cdn.modrinth.com/data/XaDC71GB/versions/IONexlgI/lithostitched-1.7.2-neoforge-21.1.jar",
       "sha1": "ce35206214647131ebdf14212d1986349aeba79a",
-                     "size":  810015
+      "size": 810015,
+      "side": "server"
     },
     {
       "source": "modrinth",
@@ -257,7 +281,8 @@
       "path": "mods/c2me-neoforge-mc1.21.1-0.3.0+alpha.0.91.jar",
       "url": "https://cdn.modrinth.com/data/COlSi5iR/versions/9iPiN34N/c2me-neoforge-mc1.21.1-0.3.0%2Balpha.0.91.jar",
       "sha1": "c858c8becfb5205eb12aaf0420eb82c307c2e6a7",
-                     "size":  4508649
+      "size": 4508649,
+      "side": "both"
     },
     {
       "source": "modrinth",
@@ -267,7 +292,8 @@
       "path": "mods/noisium-neoforge-2.3.0+mc1.21-1.21.1.jar",
       "url": "https://cdn.modrinth.com/data/KuNKN7d2/versions/nJBE6tif/noisium-neoforge-2.3.0%2Bmc1.21-1.21.1.jar",
       "sha1": "1bea6b61378ba80f038256c4345d9ff3b67928c4",
-                     "size":  60296
+      "size": 60296,
+      "side": "server"
     },
     {
       "source": "modrinth",
@@ -277,7 +303,8 @@
       "path": "mods/async-locator-refined-neoforge-1.21.1-1.5.3.jar",
       "url": "https://cdn.modrinth.com/data/LUIHK4LD/versions/3BdGHbV2/async-locator-refined-neoforge-1.21.1-1.5.3.jar",
       "sha1": "2993e3efc6d211ad8d4db179851dea6fdfff4e07",
-                     "size":  273320
+      "size": 273320,
+      "side": "server"
     },
     {
       "source": "modrinth",
@@ -287,7 +314,8 @@
       "path": "mods/servercore-neoforge-1.5.10+1.21.1.jar",
       "url": "https://cdn.modrinth.com/data/4WWQxlQP/versions/77MAnmOn/servercore-neoforge-1.5.10%2B1.21.1.jar",
       "sha1": "4524cd40cfa5019d8b5fbcb628b1616031838a0c",
-                     "size":  1429522
+      "size": 1429522,
+      "side": "server"
     },
     {
       "source": "modrinth",
@@ -297,7 +325,8 @@
       "path": "mods/lithium-neoforge-0.15.3+mc1.21.1.jar",
       "url": "https://cdn.modrinth.com/data/gvQqBUqZ/versions/RXHf27Wv/lithium-neoforge-0.15.3%2Bmc1.21.1.jar",
       "sha1": "9fd5fa9076044180ae7f51672de74669196ec72e",
-                     "size":  774148
+      "size": 774148,
+      "side": "both"
     },
     {
       "source": "modrinth",
@@ -307,7 +336,8 @@
       "path": "mods/geckolib-neoforge-1.21.1-4.8.4.jar",
       "url": "https://cdn.modrinth.com/data/8BmcQJ2H/versions/gFmrC8Ru/geckolib-neoforge-1.21.1-4.8.4.jar",
       "sha1": "eb854c8ec53ef922a5f3877a1aa4c1ce1352e0ce",
-                     "size":  622582
+      "size": 622582,
+      "side": "both"
     },
     {
       "source": "modrinth",
@@ -317,7 +347,8 @@
       "path": "mods/curios-neoforge-9.5.1+1.21.1.jar",
       "url": "https://cdn.modrinth.com/data/vvuO3ImH/versions/yohfFbgD/curios-neoforge-9.5.1%2B1.21.1.jar",
       "sha1": "418fcd42e3a7844c9bdc71c9b6401fdb3894e0c4",
-                     "size":  410690
+      "size": 410690,
+      "side": "both"
     },
     {
       "source": "modrinth",
@@ -327,7 +358,8 @@
       "path": "mods/YungsApi-1.21.1-NeoForge-5.1.6.jar",
       "url": "https://cdn.modrinth.com/data/Ua7DFN59/versions/ZB22DE9q/YungsApi-1.21.1-NeoForge-5.1.6.jar",
       "sha1": "e1c394779fb9e038e4f7a1b4558d0432607d263b",
-                     "size":  388678
+      "size": 388678,
+      "side": "both"
     },
     {
       "source": "modrinth",
@@ -337,7 +369,30 @@
       "path": "shaderpacks/ComplementaryReimagined_r5.7.1.zip",
       "url": "https://cdn.modrinth.com/data/HVnmMxH1/versions/836bPNGo/ComplementaryReimagined_r5.7.1.zip",
       "sha1": "b560f646a124d5204b1fb7321fec373b9c346fa5",
-                     "size":  522970
+      "size": 522970,
+      "side": "client"
+    },
+    {
+      "source": "modrinth",
+      "slug": "simple-voice-chat",
+      "versionId": "6rT2RWh6",
+      "version": "neoforge-1.21.1-2.6.17",
+      "path": "mods/voicechat-neoforge-1.21.1-2.6.17.jar",
+      "url": "https://cdn.modrinth.com/data/9eGKb6K1/versions/6rT2RWh6/voicechat-neoforge-1.21.1-2.6.17.jar",
+      "sha1": "55fc0d529318620bd2ce7a635657014c5c98e189",
+      "size": 4902096,
+      "side": "both"
+    },
+    {
+      "source": "modrinth",
+      "slug": "almostunified",
+      "versionId": "e8iYxxI3",
+      "version": "1.21.1-1.4.2+neoforge",
+      "path": "mods/almostunified-neoforge-1.21.1-1.4.2.jar",
+      "url": "https://cdn.modrinth.com/data/sdaSaQEz/versions/e8iYxxI3/almostunified-neoforge-1.21.1-1.4.2.jar",
+      "sha1": "f9a58fa95780f4b045d30559c1fdaedaa7f0fba3",
+      "size": 295093,
+      "side": "both"
     }
   ],
   "defaultServer": {

scripts/Bootstrap-Sides.ps1

@@ -0,0 +1,96 @@
+#requires -Version 7
+<#
+.SYNOPSIS
+    Populate the `side` field on each mod entry in pack.lock.json by querying
+    Modrinth's project metadata. Run once after schema migration; thereafter,
+    Update-Pack.ps1 should set side automatically when adding new mods.
+
+.DESCRIPTION
+    Modrinth returns `client_side` and `server_side` per project, with values
+    `required` / `optional` / `unsupported` / `unknown`. We map:
+      server_side = unsupported          -> side = "client"   (skip on server)
+      client_side = unsupported          -> side = "server"   (skip on launcher)
+      both required/optional/unknown     -> side = "both"     (install everywhere)
+
+    Conservative: only marks a mod side-restricted when the OTHER side is
+    explicitly `unsupported`. Anything ambiguous stays "both".
+
+    CurseForge mods can't be queried (no API key here) -- left at "both" by
+    default, manual edit if needed.
+
+.PARAMETER LockPath
+    pack.lock.json to update in place. Defaults to ../pack/pack.lock.json.
+
+.PARAMETER DryRun
+    Print proposed changes without writing the file.
+#>
+
+[CmdletBinding()]
+param(
+    [string]$LockPath = $(Join-Path (Split-Path -Parent $MyInvocation.MyCommand.Path) '..\pack\pack.lock.json'),
+    [switch]$DryRun
+)
+
+$ErrorActionPreference = 'Stop'
+$ProgressPreference    = 'SilentlyContinue'
+
+$LockPath = (Resolve-Path $LockPath).Path
+$json = Get-Content $LockPath -Raw | ConvertFrom-Json -Depth 20
+
+if (-not $json.mods) { throw "pack.lock.json has no 'mods' array." }
+
+function Get-ModrinthSide {
+    param([string]$Slug)
+    $proj = Invoke-RestMethod -Uri "https://api.modrinth.com/v2/project/$Slug" `
+                              -Headers @{ 'User-Agent' = 'BrassAndSigil-Launcher/0.1 (matt@sijbers.uk)' }
+    $cs = $proj.client_side; $ss = $proj.server_side
+    if ($ss -eq 'unsupported' -and $cs -ne 'unsupported')      { return 'client' }
+    elseif ($cs -eq 'unsupported' -and $ss -ne 'unsupported')  { return 'server' }
+    else                                                       { return 'both'   }
+}
+
+Write-Host ""
+Write-Host "Bootstrapping side field on $($json.mods.Count) mods..."
+Write-Host ""
+
+$changes = 0
+foreach ($mod in $json.mods) {
+    $existing = if ($mod.PSObject.Properties.Name -contains 'side') { $mod.side } else { $null }
+    if ($mod.source -ne 'modrinth') {
+        # CurseForge or other: default to 'both' if missing, leave alone otherwise.
+        if (-not $existing) {
+            $mod | Add-Member -NotePropertyName 'side' -NotePropertyValue 'both' -Force
+            Write-Host ("  [{0}] {1,-26} {2}" -f $mod.source.PadRight(7).Substring(0,7), $mod.slug, 'both (default; non-modrinth)')
+            $changes++
+        }
+        continue
+    }
+    try {
+        $side = Get-ModrinthSide -Slug $mod.slug
+    } catch {
+        Write-Warning ("  $($mod.slug) lookup failed: $($_.Exception.Message) -- leaving as 'both'")
+        $side = 'both'
+    }
+    if ($existing -ne $side) {
+        $mod | Add-Member -NotePropertyName 'side' -NotePropertyValue $side -Force
+        Write-Host ("  [{0}] {1,-26} {2}" -f $mod.source.PadRight(7).Substring(0,7), $mod.slug, $side)
+        $changes++
+    } else {
+        Write-Host ("  [{0}] {1,-26} {2} (unchanged)" -f $mod.source.PadRight(7).Substring(0,7), $mod.slug, $side) -ForegroundColor DarkGray
+    }
+    Start-Sleep -Milliseconds 100  # be polite to Modrinth's API
+}
+
+Write-Host ""
+Write-Host "$changes mod(s) updated."
+
+if ($DryRun) {
+    Write-Host "DryRun: not writing $LockPath." -ForegroundColor DarkGray
+    exit 0
+}
+
+# Round-trip via JSON: Modrinth-returned ConvertFrom-Json objects don't always
+# round-trip with consistent property order, so we serialise with sorted keys
+# at the mod level to keep the lockfile diff minimal.
+$json | ConvertTo-Json -Depth 20 | Set-Content -Path $LockPath -Encoding utf8
+Write-Host "Wrote $LockPath" -ForegroundColor Green

scripts/Build-Pack.ps1

@@ -77,14 +77,21 @@ $files = @()
 $totalBytes = 0L
 
 foreach ($mod in $lock.mods) {
-    $files += [pscustomobject]@{
+    # `side` is emitted only when explicitly set in the lockfile -- a missing or
+    # null lockfile side means "both", and we keep the manifest clean by omitting
+    # the field rather than serialising "both" everywhere.
+    $entry = [ordered]@{
         path = $mod.path
         url  = $mod.url
         sha1 = $mod.sha1
         size = $mod.size
     }
+    $hasSide = ($mod.PSObject.Properties.Name -contains 'side') -and $mod.side -and $mod.side -ne 'both'
+    if ($hasSide) { $entry.side = $mod.side }
+    $files += [pscustomobject]$entry
     $totalBytes += $mod.size
-    Write-Host ("  [{0}] {1,-26} {2,-22} {3,8:N0} KB" -f $mod.source.PadRight(7).Substring(0,7), $mod.slug, $mod.version, ($mod.size/1KB))
+    $sideTag = if ($hasSide) { "  [$($mod.side)]" } else { '' }
+    Write-Host ("  [{0}] {1,-26} {2,-22} {3,8:N0} KB{4}" -f $mod.source.PadRight(7).Substring(0,7), $mod.slug, $mod.version, ($mod.size/1KB), $sideTag)
 }
 
 # Local overrides (configs, custom files not on Modrinth/CurseForge)
@@ -156,8 +163,25 @@ if ($LauncherExePath) {
     }
     $launcherFile = Get-Item $LauncherExePath
     $launcherVersion = $launcherFile.VersionInfo.FileVersion
+    $versionSource   = 'PE FileVersion'
+
+    # Linux PowerShell can't read PE FileVersion from a Windows .exe. When that
+    # happens, fall back to launcher/ModpackLauncher.csproj's <Version> (the
+    # source of truth that the Windows compile bakes into FileVersion anyway).
+    # Append ".0" so callers get the same 4-part form as the PE metadata.
     if ([string]::IsNullOrWhiteSpace($launcherVersion)) {
-        throw "Launcher exe has no FileVersion -- set <Version> in ModpackLauncher.csproj and republish."
+        $csprojPath = Join-Path $here '..\launcher\ModpackLauncher.csproj'
+        if (Test-Path $csprojPath) {
+            [xml]$csproj = Get-Content $csprojPath
+            $csprojVersion = ($csproj.Project.PropertyGroup.Version | Where-Object { $_ }) | Select-Object -First 1
+            if ($csprojVersion) {
+                $launcherVersion = if ($csprojVersion -match '^\d+\.\d+\.\d+$') { "$csprojVersion.0" } else { $csprojVersion }
+                $versionSource = "csproj <Version> (fallback)"
+            }
+        }
+    }
+    if ([string]::IsNullOrWhiteSpace($launcherVersion)) {
+        throw "Launcher exe has no FileVersion and csproj <Version> couldn't be read either -- set <Version> in ModpackLauncher.csproj and republish."
     }
     # FileVersion is the four-component form (e.g. "0.1.0.0" for csproj <Version>0.1.0</Version>).
     # Embed as-is -- the launcher's Version.Parse handles it directly and avoids ambiguous
@@ -167,7 +191,7 @@ if ($LauncherExePath) {
 
     Write-Host ""
     Write-Host ("Launcher metadata embedded:")
-    Write-Host ("  Version:  {0}" -f $launcherVersion)
+    Write-Host ("  Version:  {0}  ({1})" -f $launcherVersion, $versionSource)
     Write-Host ("  Url:      {0}" -f $LauncherPublicUrl)
     Write-Host ("  Source:   {0}" -f $launcherFile.FullName)
 }

scripts/Deploy-Brass.ps1

@@ -52,7 +52,10 @@ if (-not (Test-Path $cfgPath)) {
 . $cfgPath
 
 # Sanity-check required vars actually got set (template ships with CHANGE_ME).
-foreach ($v in 'DeployShare','ServerSshHost','ServerSshKey','ServerBinaryRemote') {
+# $ServerSshKey is only required for SSH-mode deploys; skip it when ServerSshHost = 'local'.
+$requiredVars = @('DeployShare','ServerSshHost','ServerBinaryRemote')
+if ($ServerSshHost -ne 'local') { $requiredVars += 'ServerSshKey' }
+foreach ($v in $requiredVars) {
     $val = Get-Variable -Name $v -ValueOnly -ErrorAction Stop
     if ($val -match 'CHANGE_ME' -or [string]::IsNullOrWhiteSpace($val)) {
         throw "deploy.config.ps1 has placeholder/empty `$$v. Fill it in."
@@ -120,14 +123,26 @@ if (($shouldRunPack -or $shouldRunLauncher) -and -not $DryRun -and -not $Force)
 # actually broken -- the atomic swap is safe with the daemon running). But
 # knowing the state up front lets us tailor the final "next steps" message
 # so a deploy success doesn't silently leave you on the old code.
+# Set $ServerSshHost = 'local' in deploy.config.ps1 to skip SSH entirely
+# and copy/inspect the server binary on the local filesystem. Use when the
+# deploy machine IS the server (e.g. running Deploy-Brass.ps1 on glados).
+$isLocalDeploy = ($ServerSshHost -eq 'local')
+
 $daemonWasRunning = $false
 if ($shouldRunServer) {
+    if ($isLocalDeploy) {
+        Write-Host "Pre-flight: checking daemon state locally..." -ForegroundColor DarkGray
+        $pgrepOut = & pgrep -f '/brass-sigil-server($| )' 2>$null
+    } else {
         Write-Host "Pre-flight: checking daemon state on $ServerSshHost..." -ForegroundColor DarkGray
         # Single-quoted PS string so PowerShell doesn't try to interpret the
-    # bash-side metacharacters. The remote shell sees the literal pgrep
+        # bash-side metacharacters. Match the binary path followed by either
-    # command; the trailing $ anchors so we don't match run.sh wrappers.
+        # end-of-line OR a space, so we catch `brass-sigil-server run` (the
-    $remoteCmd = 'pgrep -f /brass-sigil-server$ 2>/dev/null'
+        # actual invocation) without matching the `/brass-sigil-server/...`
+        # directory path that appears in the run.sh wrapper's argv.
+        $remoteCmd = 'pgrep -f /brass-sigil-server($| ) 2>/dev/null'
         $pgrepOut = & ssh -i $ServerSshKey -o ConnectTimeout=5 -o BatchMode=yes $ServerSshHost $remoteCmd 2>$null
+    }
     $daemonWasRunning = -not [string]::IsNullOrWhiteSpace($pgrepOut)
     if ($daemonWasRunning) {
         Write-Host "  Daemon is RUNNING. Atomic swap is safe -- but you'll need to" -ForegroundColor Yellow
@@ -199,12 +214,27 @@ $overridesLocal = Join-Path $repoRoot 'pack\overrides'
 $shareFiles     = Join-Path $DeployShare 'files'
 if ($shouldRunPack -and (Test-Path $overridesLocal)) {
     Step "Mirror pack/overrides/ -> $shareFiles" {
+        # Prefer rsync where available (Linux/macOS); fall back to Windows robocopy.
+        # Both perform a mirror: orphan files in the destination are removed so
+        # the share matches the local overrides exactly.
+        if (Get-Command rsync -ErrorAction SilentlyContinue) {
+            $src = ($overridesLocal -replace '\\','/').TrimEnd('/') + '/'
+            $dst = ($shareFiles    -replace '\\','/').TrimEnd('/') + '/'
+            if (-not (Test-Path $shareFiles)) { New-Item -ItemType Directory -Path $shareFiles -Force | Out-Null }
+            & rsync -a --delete $src $dst
+            if ($LASTEXITCODE -ne 0) { throw "rsync failed with exit $LASTEXITCODE" }
+        }
+        elseif (Get-Command robocopy -ErrorAction SilentlyContinue) {
             # /MIR makes destination match source (deletes orphan files in $shareFiles).
             # /XJ skips junctions, /R:1 /W:1 keeps retry behaviour sane on flaky shares.
             robocopy $overridesLocal $shareFiles /MIR /XJ /R:1 /W:1 /NFL /NDL /NJH /NJS /NP | Out-Host
             # Robocopy returns 0-7 for success-with-info; 8+ is real failure.
             if ($LASTEXITCODE -ge 8) { throw "robocopy failed with exit $LASTEXITCODE" }
         }
+        else {
+            throw "Neither rsync nor robocopy is available -- can't mirror pack overrides."
+        }
+    }
 }
 
 # ─── Stage 5: publish launcher exe (only when Stage includes Launcher) ─────
@@ -224,8 +254,19 @@ if ($shouldRunPack) {
     }
 }
 
-# ─── Stage 6: scp + atomic swap server binary ──────────────────────────────
+# ─── Stage 6: copy + atomic swap server binary ─────────────────────────────
 if ($shouldRunServer) {
+    if ($isLocalDeploy) {
+        Step "Copy server binary -> $ServerBinaryRemote (local atomic swap)" {
+            $localNew = "$ServerBinaryRemote.new"
+            Copy-Item $serverExe $localNew -Force
+            & chmod +x $localNew
+            if ($LASTEXITCODE -ne 0) { throw "chmod failed with exit $LASTEXITCODE" }
+            Move-Item $localNew $ServerBinaryRemote -Force
+            $md5 = (& md5sum $ServerBinaryRemote) -split '\s+' | Select-Object -First 1
+            Write-Host "      md5: $md5" -ForegroundColor DarkGray
+        }
+    } else {
         Step "scp server binary -> $ServerSshHost`:$ServerBinaryRemote (atomic swap)" {
             $remoteNew = "$ServerBinaryRemote.new"
             & scp -i $ServerSshKey -o ConnectTimeout=15 $serverExe "$ServerSshHost`:$remoteNew"
@@ -234,6 +275,7 @@ if ($shouldRunServer) {
             & ssh -i $ServerSshKey -o ConnectTimeout=10 $ServerSshHost $cmd
             if ($LASTEXITCODE -ne 0) { throw "ssh swap failed with exit $LASTEXITCODE" }
         }
+    }
     Write-Host ""
     if ($daemonWasRunning) {
         Write-Host "Server binary swapped on disk, but the daemon was running before this" -ForegroundColor Yellow

scripts/deploy.config.template.ps1

@@ -19,13 +19,20 @@ $ManifestPublicUrl = 'https://CHANGE_ME/pack/manifest.json'
 
 # ─── Server (brass-sigil-server daemon host) ───────────────────────────────
 # user@host for the Linux box running the daemon.
+#
+# Set to the literal string 'local' if Deploy-Brass.ps1 is being run on the
+# server itself (e.g. on glados over the Telegram bridge). In local mode the
+# script skips scp/ssh and copies the binary directly to $ServerBinaryRemote
+# with an in-place atomic rename; $ServerSshKey is ignored.
 $ServerSshHost     = 'user@CHANGE_ME'
 
 # Path to the local SSH private key authorised on the server.
+# Ignored when $ServerSshHost = 'local'.
 $ServerSshKey      = "$env:USERPROFILE\.ssh\id_ed25519"
 
-# Absolute path on the Linux box where the brass-sigil-server binary lives.
+# Absolute path where the brass-sigil-server binary lives -- on the remote
-# `Deploy-Brass.ps1` uploads to "<this>.new" then `mv` over for atomic swap.
+# host in SSH mode, on the local filesystem in 'local' mode.
+# `Deploy-Brass.ps1` writes to "<this>.new" then renames over for atomic swap.
 $ServerBinaryRemote = '/home/user/brass-sigil-server/brass-sigil-server'
 
 # ─── Build outputs (don't normally need to change) ─────────────────────────

server/Models/Manifest.cs

@@ -37,6 +37,12 @@ public sealed class ManifestFile
     [JsonPropertyName("url")]  public string  Url  { get; set; } = "";
     [JsonPropertyName("sha1")] public string? Sha1 { get; set; }
     [JsonPropertyName("size")] public long?   Size { get; set; }
+
+    /// <summary>
+    /// "both" (default), "client", or "server". Server skips "client" files;
+    /// launcher skips "server" files. Null/missing = "both".
+    /// </summary>
+    [JsonPropertyName("side")] public string? Side { get; set; }
 }
 
 public sealed class PackLock
@@ -59,4 +65,5 @@ public sealed class LockedMod
     [JsonPropertyName("url")]       public string  Url       { get; set; } = "";
     [JsonPropertyName("sha1")]      public string  Sha1      { get; set; } = "";
     [JsonPropertyName("size")]      public long    Size      { get; set; }
+    [JsonPropertyName("side")]      public string? Side      { get; set; }
 }

server/Services/ManifestSync.cs

@@ -38,12 +38,20 @@ public sealed class ManifestSync
         progress?.Report($"Pack: {manifest.Name} v{manifest.Version}");
         Directory.CreateDirectory(serverDir);
 
-        // Resolve which mods are server-side.
+        // Build-time tagging is authoritative: anything marked "client" is dropped
-        var skipSlugs = await ResolveServerSideSkipListAsync(manifest, ct);
+        // outright, anything marked "server" or "both" is kept. We only fall back
+        // to the runtime Modrinth lookup for files with NO explicit side -- this
+        // keeps un-tagged (or CurseForge-only) mods safe and matches pre-side
+        // behaviour for them.
+        var needsLookup = manifest.Files.Where(f => string.IsNullOrEmpty(f.Side)).ToList();
+        var skipSlugs = needsLookup.Count > 0
+            ? await ResolveServerSideSkipListAsync(
+                new Manifest { Files = needsLookup }, ct)
+            : new HashSet<string>(StringComparer.OrdinalIgnoreCase);
 
         // Build the filtered list of files to keep on the server.
         var keepFiles = manifest.Files
-            .Where(f => !ShouldSkipFile(f.Path, skipSlugs))
+            .Where(f => !IsClientOnly(f) && (!string.IsNullOrEmpty(f.Side) || !ShouldSkipFile(f.Path, skipSlugs)))
             .ToList();
         var skippedCount = manifest.Files.Count - keepFiles.Count;
 
@@ -108,6 +116,9 @@ public sealed class ManifestSync
                                   || name.Equals(slug, StringComparison.OrdinalIgnoreCase));
     }
 
+    private static bool IsClientOnly(ManifestFile f)
+        => string.Equals(f.Side, "client", StringComparison.OrdinalIgnoreCase);
+
     /// <summary>Walk the manifest's mod URLs; for Modrinth ones, look up server_side; build a skip set.</summary>
     private async Task<HashSet<string>> ResolveServerSideSkipListAsync(Manifest manifest, CancellationToken ct)
     {