fix(workspace): prioritize custom files over installation data and isolate user workspaces

GenHub/GenHub.Core/Extensions/WorkspaceConfigurationExtensions.cs

@@ -1,4 +1,7 @@
+using System;
+using System.Collections.Generic;
 using System.Linq;
+using GenHub.Core.Models.Enums;
 using GenHub.Core.Models.Manifest;
 using GenHub.Core.Models.Workspace;
 
@@ -11,34 +14,74 @@ public static class WorkspaceConfigurationExtensions
 {
     /// <summary>
     /// Gets all unique files from all manifests, deduplicated by relative path.
-    /// When multiple manifests contain the same file path, returns the first occurrence.
+    /// When multiple manifests contain the same file path, returns the file from the highest priority manifest.
     /// </summary>
     /// <param name="configuration">The workspace configuration to get files from.</param>
     /// <returns>An enumerable of unique manifest files.</returns>
     public static IEnumerable<ManifestFile> GetAllUniqueFiles(
         this WorkspaceConfiguration configuration)
     {
+        if (configuration?.Manifests is null || configuration.Manifests.Count == 0)
+        {
+            return [];
+        }
+
         return configuration.Manifests
-            .SelectMany(m => (m.Files ?? []).Select(f => new { File = f, Manifest = m }))
+            .SelectMany((m, index) => (m.Files ?? []).Select(f => new { File = f, Manifest = m, ManifestIndex = index }))
             .GroupBy(x => x.File.RelativePath, StringComparer.OrdinalIgnoreCase)
             .Select(g => g.OrderByDescending(x => ContentTypePriority.GetPriority(x.Manifest.ContentType))
+                          .ThenByDescending(x => x.ManifestIndex)
                           .First().File);
     }
 
     /// <summary>
     /// Gets all unique files intended for the workspace from all manifests, deduplicated by relative path.
-    /// Only includes files where <see cref="ManifestFile.InstallTarget"/> is <see cref="GenHub.Core.Models.Enums.ContentInstallTarget.Workspace"/>.
+    /// Only includes files where <see cref="ManifestFile.InstallTarget"/> is <see cref="ContentInstallTarget.Workspace"/>.
+    /// Higher-priority manifests (such as mods and patches) take precedence over lower-priority manifests (such as base game installations).
     /// </summary>
     /// <param name="configuration">The workspace configuration to get files from.</param>
     /// <returns>An enumerable of unique workspace-specific manifest files.</returns>
     public static IEnumerable<ManifestFile> GetWorkspaceUniqueFiles(
         this WorkspaceConfiguration configuration)
     {
+        if (configuration?.Manifests is null || configuration.Manifests.Count == 0)
+        {
+            return [];
+        }
+
         return configuration.Manifests
-            .SelectMany(m => (m.Files ?? []).Select(f => new { File = f, Manifest = m }))
-            .Where(x => x.File.InstallTarget == GenHub.Core.Models.Enums.ContentInstallTarget.Workspace)
+            .SelectMany((m, index) => (m.Files ?? []).Select(f => new { File = f, Manifest = m, ManifestIndex = index }))
+            .Where(x => x.File.InstallTarget == ContentInstallTarget.Workspace)
             .GroupBy(x => x.File.RelativePath, StringComparer.OrdinalIgnoreCase)
             .Select(g => g.OrderByDescending(x => ContentTypePriority.GetPriority(x.Manifest.ContentType))
+                          .ThenByDescending(x => x.ManifestIndex)
                           .First().File);
     }
+
+    /// <summary>
+    /// Gets all unique workspace files paired with their owning manifest, deduplicated by relative path
+    /// and resolved by content type priority (higher-priority content types override lower-priority ones).
+    /// </summary>
+    /// <param name="configuration">The workspace configuration to get prioritized files from.</param>
+    /// <returns>A read-only list of prioritized file and manifest pairs.</returns>
+    public static IReadOnlyList<(ManifestFile File, ContentManifest Manifest)> GetPrioritizedWorkspaceFiles(
+        this WorkspaceConfiguration configuration)
+    {
+        if (configuration?.Manifests is null || configuration.Manifests.Count == 0)
+        {
+            return [];
+        }
+
+        return configuration.Manifests
+            .SelectMany((manifest, index) => (manifest.Files ?? Enumerable.Empty<ManifestFile>())
+                .Where(f => f.InstallTarget == ContentInstallTarget.Workspace)
+                .Select(file => new { File = file, Manifest = manifest, ManifestIndex = index }))
+            .GroupBy(x => x.File.RelativePath, StringComparer.OrdinalIgnoreCase)
+            .Select(g => g
+                .OrderByDescending(x => ContentTypePriority.GetPriority(x.Manifest.ContentType))
+                .ThenByDescending(x => x.ManifestIndex)
+                .First())
+            .Select(x => (x.File, x.Manifest))
+            .ToList();
+    }
 }

GenHub/GenHub.Tests/GenHub.Tests.Core/Features/Workspace/GameProfileWorkspaceIntegrationTest.cs

@@ -163,14 +163,14 @@ public async Task PrepareWorkspace_FullCopyStrategy_CopiesGameInstallationAndCli
     [Fact]
     public async Task PrepareWorkspace_SymlinkStrategy_LinksGameInstallationAndClientFilesAsync()
     {
-        // Skip on systems that don't support symlinks
+        // Skip on Windows if not running with administrator privileges
         bool isWindows = OperatingSystem.IsWindows();
         bool isAdmin = isWindows &&
             new System.Security.Principal.WindowsPrincipal(
                 System.Security.Principal.WindowsIdentity.GetCurrent())
             .IsInRole(System.Security.Principal.WindowsBuiltInRole.Administrator);
 
-        if (!isWindows || !isAdmin)
+        if (isWindows && !isAdmin)
         {
             return;
         }
@@ -228,7 +228,7 @@ public async Task PrepareWorkspace_MixedContentTypes_HandlesGameInstallationAndG
                 System.Security.Principal.WindowsIdentity.GetCurrent())
             .IsInRole(System.Security.Principal.WindowsBuiltInRole.Administrator);
 
-        if (!isWindows || !isAdmin)
+        if (isWindows && !isAdmin)
         {
             return;
         }
@@ -336,7 +336,7 @@ public async Task PrepareWorkspace_AllStrategies_HandleGameInstallationFilesAsyn
 
         // Skip symlink strategies when not admin on Windows
         if ((strategy == WorkspaceStrategy.SymlinkOnly || strategy == WorkspaceStrategy.HybridCopySymlink) &&
-            (!isWindows || !isAdmin))
+            isWindows && !isAdmin)
         {
             return;
         }

GenHub/GenHub.Tests/GenHub.Tests.Core/Features/Workspace/WorkspaceIntegrationTests.cs

@@ -114,7 +114,7 @@ public async Task EndToEndWorkspaceCreation_AllStrategiesAsync(WorkspaceStrategy
 
         if ((strategy == WorkspaceStrategy.SymlinkOnly ||
              strategy == WorkspaceStrategy.HybridCopySymlink) &&
-            (!isWindows || !isAdmin))
+            isWindows && !isAdmin)
         {
             return;
         }