rewrite content logic to decentralise cache (#488)

This is necessary due to changes in Stardew Valley 1.3, which now changes loaded assets and expects those changes to be persisted but not propagated to other content managers.

7 files changed, 402 insertions, 482 deletions

diff --git a/src/SMAPI/Framework/ContentCoordinator.cs b/src/SMAPI/Framework/ContentCoordinator.cs
new file mode 100644
index 00000000..86ebc5c3
--- /dev/null
+++ b/src/SMAPI/Framework/ContentCoordinator.cs
@@ -0,0 +1,175 @@
+using System;
+using System.Collections.Generic;
+using System.Globalization;
+using System.IO;
+using System.Linq;
+using System.Reflection;
+using Microsoft.Xna.Framework.Content;
+using StardewModdingAPI.Framework.Content;
+using StardewModdingAPI.Framework.Reflection;
+using StardewModdingAPI.Metadata;
+using StardewValley;
+
+namespace StardewModdingAPI.Framework
+{
+    /// <summary>The central logic for creating content managers, invalidating caches, and propagating asset changes.</summary>
+    internal class ContentCoordinator : IDisposable
+    {
+        /*********
+        ** Properties
+        *********/
+        /// <summary>Encapsulates monitoring and logging.</summary>
+        private readonly IMonitor Monitor;
+
+        /// <summary>Provides metadata for core game assets.</summary>
+        private readonly CoreAssetPropagator CoreAssets;
+
+        /// <summary>Simplifies access to private code.</summary>
+        private readonly Reflector Reflection;
+
+        /// <summary>The loaded content managers (including the <see cref="MainContentManager"/>).</summary>
+        private readonly IList<SContentManager> ContentManagers = new List<SContentManager>();
+
+
+        /*********
+        ** Accessors
+        *********/
+        /// <summary>The primary content manager used for most assets.</summary>
+        public SContentManager MainContentManager { get; private set; }
+
+        /// <summary>The current language as a constant.</summary>
+        public LocalizedContentManager.LanguageCode Language => this.MainContentManager.Language;
+
+        /// <summary>Interceptors which provide the initial versions of matching assets.</summary>
+        public IDictionary<IModMetadata, IList<IAssetLoader>> Loaders { get; } = new Dictionary<IModMetadata, IList<IAssetLoader>>();
+
+        /// <summary>Interceptors which edit matching assets after they're loaded.</summary>
+        public IDictionary<IModMetadata, IList<IAssetEditor>> Editors { get; } = new Dictionary<IModMetadata, IList<IAssetEditor>>();
+
+        /// <summary>The absolute path to the <see cref="ContentManager.RootDirectory"/>.</summary>
+        public string FullRootDirectory { get; }
+
+
+        /*********
+        ** Public methods
+        *********/
+        /// <summary>Construct an instance.</summary>
+        /// <param name="serviceProvider">The service provider to use to locate services.</param>
+        /// <param name="rootDirectory">The root directory to search for content.</param>
+        /// <param name="currentCulture">The current culture for which to localise content.</param>
+        /// <param name="monitor">Encapsulates monitoring and logging.</param>
+        /// <param name="reflection">Simplifies access to private code.</param>
+        public ContentCoordinator(IServiceProvider serviceProvider, string rootDirectory, CultureInfo currentCulture, IMonitor monitor, Reflector reflection)
+        {
+            this.Monitor = monitor ?? throw new ArgumentNullException(nameof(monitor));
+            this.Reflection = reflection;
+            this.FullRootDirectory = Path.Combine(Constants.ExecutionPath, rootDirectory);
+            this.ContentManagers.Add(
+                this.MainContentManager = new SContentManager("Game1.content", serviceProvider, rootDirectory, currentCulture, this, monitor, reflection, isModFolder: false)
+            );
+            this.CoreAssets = new CoreAssetPropagator(this.MainContentManager.NormaliseAssetName, reflection);
+        }
+
+        /// <summary>Get a new content manager which defers loading to the content core.</summary>
+        /// <param name="name">A name for the mod manager. Not guaranteed to be unique.</param>
+        /// <param name="isModFolder">Whether this content manager is wrapped around a mod folder.</param>
+        /// <param name="rootDirectory">The root directory to search for content (or <c>null</c>. for the default)</param>
+        public SContentManager CreateContentManager(string name, bool isModFolder, string rootDirectory = null)
+        {
+            return new SContentManager(name, this.MainContentManager.ServiceProvider, rootDirectory ?? this.MainContentManager.RootDirectory, this.MainContentManager.CurrentCulture, this, this.Monitor, this.Reflection, isModFolder);
+        }
+
+        /// <summary>Get the current content locale.</summary>
+        public string GetLocale() => this.MainContentManager.GetLocale(LocalizedContentManager.CurrentLanguageCode);
+
+        /// <summary>Convert an absolute file path into a appropriate asset name.</summary>
+        /// <param name="absolutePath">The absolute path to the file.</param>
+        public string GetAssetNameFromFilePath(string absolutePath) => this.MainContentManager.GetAssetNameFromFilePath(absolutePath, ContentSource.GameContent);
+
+        /// <summary>Purge assets from the cache that match one of the interceptors.</summary>
+        /// <param name="editors">The asset editors for which to purge matching assets.</param>
+        /// <param name="loaders">The asset loaders for which to purge matching assets.</param>
+        /// <returns>Returns the invalidated asset names.</returns>
+        public IEnumerable<string> InvalidateCacheFor(IAssetEditor[] editors, IAssetLoader[] loaders)
+        {
+            if (!editors.Any() && !loaders.Any())
+                return new string[0];
+
+            // get CanEdit/Load methods
+            MethodInfo canEdit = typeof(IAssetEditor).GetMethod(nameof(IAssetEditor.CanEdit));
+            MethodInfo canLoad = typeof(IAssetLoader).GetMethod(nameof(IAssetLoader.CanLoad));
+            if (canEdit == null || canLoad == null)
+                throw new InvalidOperationException("SMAPI could not access the interceptor methods."); // should never happen
+
+            // invalidate matching keys
+            return this.InvalidateCache(asset =>
+            {
+                // check loaders
+                MethodInfo canLoadGeneric = canLoad.MakeGenericMethod(asset.DataType);
+                if (loaders.Any(loader => (bool)canLoadGeneric.Invoke(loader, new object[] { asset })))
+                    return true;
+
+                // check editors
+                MethodInfo canEditGeneric = canEdit.MakeGenericMethod(asset.DataType);
+                return editors.Any(editor => (bool)canEditGeneric.Invoke(editor, new object[] { asset }));
+            });
+        }
+
+        /// <summary>Purge matched assets from the cache.</summary>
+        /// <param name="predicate">Matches the asset keys to invalidate.</param>
+        /// <param name="dispose">Whether to dispose invalidated assets. This should only be <c>true</c> when they're being invalidated as part of a dispose, to avoid crashing the game.</param>
+        /// <returns>Returns the invalidated asset keys.</returns>
+        public IEnumerable<string> InvalidateCache(Func<IAssetInfo, bool> predicate, bool dispose = false)
+        {
+            string locale = this.GetLocale();
+            return this.InvalidateCache((assetName, type) =>
+            {
+                IAssetInfo info = new AssetInfo(locale, assetName, type, this.MainContentManager.NormaliseAssetName);
+                return predicate(info);
+            });
+        }
+
+        /// <summary>Purge matched assets from the cache.</summary>
+        /// <param name="predicate">Matches the asset keys to invalidate.</param>
+        /// <param name="dispose">Whether to dispose invalidated assets. This should only be <c>true</c> when they're being invalidated as part of a dispose, to avoid crashing the game.</param>
+        /// <returns>Returns the invalidated asset names.</returns>
+        public IEnumerable<string> InvalidateCache(Func<string, Type, bool> predicate, bool dispose = false)
+        {
+            // invalidate cache
+            HashSet<string> removedAssetNames = new HashSet<string>();
+            foreach (SContentManager contentManager in this.ContentManagers)
+            {
+                foreach (string name in contentManager.InvalidateCache(predicate, dispose))
+                    removedAssetNames.Add(name);
+            }
+
+            // reload core game assets
+            int reloaded = 0;
+            foreach (string key in removedAssetNames)
+            {
+                if (this.CoreAssets.Propagate(this.MainContentManager, key)) // use an intercepted content manager
+                    reloaded++;
+            }
+
+            // report result
+            if (removedAssetNames.Any())
+                this.Monitor.Log($"Invalidated {removedAssetNames.Count} asset names: {string.Join(", ", removedAssetNames.OrderBy(p => p, StringComparer.InvariantCultureIgnoreCase))}. Reloaded {reloaded} core assets.", LogLevel.Trace);
+            this.Monitor.Log("Invalidated 0 cache entries.", LogLevel.Trace);
+
+            return removedAssetNames;
+        }
+
+        /// <summary>Dispose held resources.</summary>
+        public void Dispose()
+        {
+            if (this.MainContentManager == null)
+                return; // already disposed
+
+            this.Monitor.Log("Disposing the content coordinator. Content managers will no longer be usable after this point.", LogLevel.Trace);
+            foreach (SContentManager contentManager in this.ContentManagers)
+                contentManager.Dispose();
+            this.ContentManagers.Clear();
+            this.MainContentManager = null;
+        }
+    }
+}
diff --git a/src/SMAPI/Framework/ContentManagerShim.cs b/src/SMAPI/Framework/ContentManagerShim.cs
deleted file mode 100644
index 66754fd7..00000000
--- a/src/SMAPI/Framework/ContentManagerShim.cs
+++ /dev/null
@@ -1,91 +0,0 @@
-using System;
-using System.Globalization;
-using StardewValley;
-
-namespace StardewModdingAPI.Framework
-{
-    /// <summary>A minimal content manager which defers to SMAPI's core content logic.</summary>
-    internal class ContentManagerShim : LocalizedContentManager
-    {
-        /*********
-        ** Properties
-        *********/
-        /// <summary>SMAPI's core content logic.</summary>
-        private readonly ContentCore ContentCore;
-
-
-        /*********
-        ** Accessors
-        *********/
-        /// <summary>The content manager's name for logs (if any).</summary>
-        public string Name { get; }
-
-
-        /*********
-        ** Public methods
-        *********/
-        /// <summary>Construct an instance.</summary>
-        /// <param name="contentCore">SMAPI's core content logic.</param>
-        /// <param name="name">The content manager's name for logs (if any).</param>
-        /// <param name="serviceProvider">The service provider to use to locate services.</param>
-        /// <param name="rootDirectory">The root directory to search for content.</param>
-        /// <param name="currentCulture">The current culture for which to localise content.</param>
-        public ContentManagerShim(ContentCore contentCore, string name, IServiceProvider serviceProvider, string rootDirectory, CultureInfo currentCulture)
-                : base(serviceProvider, rootDirectory, currentCulture)
-        {
-            this.ContentCore = contentCore;
-            this.Name = name;
-        }
-
-        /// <summary>Load an asset that has been processed by the content pipeline.</summary>
-        /// <typeparam name="T">The type of asset to load.</typeparam>
-        /// <param name="assetName">The asset path relative to the loader root directory, not including the <c>.xnb</c> extension.</param>
-        public override T Load<T>(string assetName)
-        {
-            return this.Load<T>(assetName, LocalizedContentManager.CurrentLanguageCode);
-        }
-
-        /// <summary>Load an asset that has been processed by the content pipeline.</summary>
-        /// <typeparam name="T">The type of asset to load.</typeparam>
-        /// <param name="assetName">The asset path relative to the loader root directory, not including the <c>.xnb</c> extension.</param>
-        /// <param name="language">The language code for which to load content.</param>
-        public override T Load<T>(string assetName, LanguageCode language)
-        {
-            return this.ContentCore.Load<T>(assetName, this, language);
-        }
-
-        /// <summary>Load the base asset without localisation.</summary>
-        /// <typeparam name="T">The type of asset to load.</typeparam>
-        /// <param name="assetName">The asset path relative to the loader root directory, not including the <c>.xnb</c> extension.</param>
-        public override T LoadBase<T>(string assetName)
-        {
-            return this.Load<T>(assetName, LanguageCode.en);
-        }
-
-        /// <summary>Inject an asset into the cache.</summary>
-        /// <typeparam name="T">The type of asset to inject.</typeparam>
-        /// <param name="assetName">The asset path relative to the loader root directory, not including the <c>.xnb</c> extension.</param>
-        /// <param name="value">The asset value.</param>
-        public void Inject<T>(string assetName, T value)
-        {
-            this.ContentCore.Inject<T>(assetName, value, this);
-        }
-
-        /// <summary>Create a new content manager for temporary use.</summary>
-        public override LocalizedContentManager CreateTemporary()
-        {
-            return this.ContentCore.CreateContentManager("(temporary)");
-        }
-
-
-        /*********
-        ** Protected methods
-        *********/
-        /// <summary>Dispose held resources.</summary>
-        /// <param name="disposing">Whether the content manager is disposing (rather than finalising).</param>
-        protected override void Dispose(bool disposing)
-        {
-            this.ContentCore.DisposeFor(this);
-        }
-    }
-}
diff --git a/src/SMAPI/Framework/ModHelpers/ContentHelper.cs b/src/SMAPI/Framework/ModHelpers/ContentHelper.cs
index c7d4c39e..4a71f7e7 100644
--- a/src/SMAPI/Framework/ModHelpers/ContentHelper.cs
+++ b/src/SMAPI/Framework/ModHelpers/ContentHelper.cs
@@ -23,10 +23,10 @@ namespace StardewModdingAPI.Framework.ModHelpers
         ** Properties
         *********/
         /// <summary>SMAPI's core content logic.</summary>
-        private readonly ContentCore ContentCore;
+        private readonly ContentCoordinator ContentCore;
 
         /// <summary>The content manager for this mod.</summary>
-        private readonly ContentManagerShim ContentManager;
+        private readonly SContentManager ContentManager;
 
         /// <summary>The absolute path to the mod folder.</summary>
         private readonly string ModFolderPath;
@@ -42,10 +42,10 @@ namespace StardewModdingAPI.Framework.ModHelpers
         ** Accessors
         *********/
         /// <summary>The game's current locale code (like <c>pt-BR</c>).</summary>
-        public string CurrentLocale => this.ContentCore.GetLocale();
+        public string CurrentLocale => this.ContentManager.GetLocale();
 
         /// <summary>The game's current locale as an enum value.</summary>
-        public LocalizedContentManager.LanguageCode CurrentLocaleConstant => this.ContentCore.Language;
+        public LocalizedContentManager.LanguageCode CurrentLocaleConstant => this.ContentManager.Language;
 
         /// <summary>The observable implementation of <see cref="AssetEditors"/>.</summary>
         internal ObservableCollection<IAssetEditor> ObservableAssetEditors { get; } = new ObservableCollection<IAssetEditor>();
@@ -70,7 +70,7 @@ namespace StardewModdingAPI.Framework.ModHelpers
         /// <param name="modID">The unique ID of the relevant mod.</param>
         /// <param name="modName">The friendly mod name for use in errors.</param>
         /// <param name="monitor">Encapsulates monitoring and logging.</param>
-        public ContentHelper(ContentCore contentCore, ContentManagerShim contentManager, string modFolderPath, string modID, string modName, IMonitor monitor)
+        public ContentHelper(ContentCoordinator contentCore, SContentManager contentManager, string modFolderPath, string modID, string modName, IMonitor monitor)
             : base(modID)
         {
             this.ContentCore = contentCore;
@@ -96,7 +96,7 @@ namespace StardewModdingAPI.Framework.ModHelpers
                 switch (source)
                 {
                     case ContentSource.GameContent:
-                        return this.ContentManager.Load<T>(key);
+                        return this.ContentCore.MainContentManager.Load<T>(key);
 
                     case ContentSource.ModFolder:
                         // get file
@@ -105,10 +105,10 @@ namespace StardewModdingAPI.Framework.ModHelpers
                             throw GetContentError($"there's no matching file at path '{file.FullName}'.");
 
                         // get asset path
-                        string assetName = this.ContentCore.GetAssetNameFromFilePath(file.FullName);
+                        string assetName = this.ContentManager.GetAssetNameFromFilePath(file.FullName, ContentSource.ModFolder);
 
                         // try cache
-                        if (this.ContentCore.IsLoaded(assetName))
+                        if (this.ContentManager.IsLoaded(assetName))
                             return this.ContentManager.Load<T>(assetName);
 
                         // fix map tilesheets
@@ -146,7 +146,7 @@ namespace StardewModdingAPI.Framework.ModHelpers
         [Pure]
         public string NormaliseAssetName(string assetName)
         {
-            return this.ContentCore.NormaliseAssetName(assetName);
+            return this.ContentManager.NormaliseAssetName(assetName);
         }
 
         /// <summary>Get the underlying key in the game's content cache for an asset. This can be used to load custom map tilesheets, but should be avoided when you can use the content API instead. This does not validate whether the asset exists.</summary>
@@ -158,11 +158,11 @@ namespace StardewModdingAPI.Framework.ModHelpers
             switch (source)
             {
                 case ContentSource.GameContent:
-                    return this.ContentCore.NormaliseAssetName(key);
+                    return this.ContentManager.NormaliseAssetName(key);
 
                 case ContentSource.ModFolder:
                     FileInfo file = this.GetModFile(key);
-                    return this.ContentCore.NormaliseAssetName(this.ContentCore.GetAssetNameFromFilePath(file.FullName));
+                    return this.ContentManager.NormaliseAssetName(this.ContentManager.GetAssetNameFromFilePath(file.FullName, ContentSource.GameContent));
 
                 default:
                     throw new NotSupportedException($"Unknown content source '{source}'.");
@@ -177,7 +177,7 @@ namespace StardewModdingAPI.Framework.ModHelpers
         {
             string actualKey = this.GetActualAssetKey(key, ContentSource.GameContent);
             this.Monitor.Log($"Requested cache invalidation for '{actualKey}'.", LogLevel.Trace);
-            return this.ContentCore.InvalidateCache(asset => asset.AssetNameEquals(actualKey));
+            return this.ContentCore.InvalidateCache(asset => asset.AssetNameEquals(actualKey)).Any();
         }
 
         /// <summary>Remove all assets of the given type from the cache so they're reloaded on the next request. <b>This can be a very expensive operation and should only be used in very specific cases.</b> This will reload core game assets if needed, but references to the former assets will still show the previous content.</summary>
@@ -186,7 +186,7 @@ namespace StardewModdingAPI.Framework.ModHelpers
         public bool InvalidateCache<T>()
         {
             this.Monitor.Log($"Requested cache invalidation for all assets of type {typeof(T)}. This is an expensive operation and should be avoided if possible.", LogLevel.Trace);
-            return this.ContentCore.InvalidateCache((key, type) => typeof(T).IsAssignableFrom(type));
+            return this.ContentCore.InvalidateCache((key, type) => typeof(T).IsAssignableFrom(type)).Any();
         }
 
         /// <summary>Remove matching assets from the content cache so they're reloaded on the next request. This will reload core game assets if needed, but references to the former asset will still show the previous content.</summary>
@@ -195,7 +195,7 @@ namespace StardewModdingAPI.Framework.ModHelpers
         public bool InvalidateCache(Func<IAssetInfo, bool> predicate)
         {
             this.Monitor.Log("Requested cache invalidation for all assets matching a predicate.", LogLevel.Trace);
-            return this.ContentCore.InvalidateCache(predicate);
+            return this.ContentCore.InvalidateCache(predicate).Any();
         }
 
         /*********
@@ -207,7 +207,7 @@ namespace StardewModdingAPI.Framework.ModHelpers
         [SuppressMessage("ReSharper", "ParameterOnlyUsedForPreconditionCheck.Local", Justification = "Parameter is only used for assertion checks by design.")]
         private void AssertValidAssetKeyFormat(string key)
         {
-            this.ContentCore.AssertValidAssetKeyFormat(key);
+            this.ContentManager.AssertValidAssetKeyFormat(key);
             if (Path.IsPathRooted(key))
                 throw new ArgumentException("The asset key must not be an absolute path.");
         }
@@ -235,7 +235,7 @@ namespace StardewModdingAPI.Framework.ModHelpers
             // get map info
             if (!map.TileSheets.Any())
                 return;
-            mapKey = this.ContentCore.NormaliseAssetName(mapKey); // Mono's Path.GetDirectoryName doesn't handle Windows dir separators
+            mapKey = this.ContentManager.NormaliseAssetName(mapKey); // Mono's Path.GetDirectoryName doesn't handle Windows dir separators
             string relativeMapFolder = Path.GetDirectoryName(mapKey) ?? ""; // folder path containing the map, relative to the mod folder
 
             // fix tilesheets
@@ -251,7 +251,7 @@ namespace StardewModdingAPI.Framework.ModHelpers
                 string seasonalImageSource = null;
                 if (Game1.currentSeason != null)
                 {
-                    string filename = Path.GetFileName(imageSource);
+                    string filename = Path.GetFileName(imageSource) ?? throw new InvalidOperationException($"The '{imageSource}' tilesheet couldn't be loaded: filename is unexpectedly null.");
                     bool hasSeasonalPrefix =
                         filename.StartsWith("spring_", StringComparison.CurrentCultureIgnoreCase)
                         || filename.StartsWith("summer_", StringComparison.CurrentCultureIgnoreCase)
@@ -341,7 +341,7 @@ namespace StardewModdingAPI.Framework.ModHelpers
         private FileInfo GetModFile(string path)
         {
             // try exact match
-            path = Path.Combine(this.ModFolderPath, this.ContentCore.NormalisePathSeparators(path));
+            path = Path.Combine(this.ModFolderPath, this.ContentManager.NormalisePathSeparators(path));
             FileInfo file = new FileInfo(path);
 
             // try with default extension
@@ -360,7 +360,7 @@ namespace StardewModdingAPI.Framework.ModHelpers
         private FileInfo GetContentFolderFile(string key)
         {
             // get file path
-            string path = Path.Combine(this.ContentCore.FullRootDirectory, key);
+            string path = Path.Combine(this.ContentManager.FullRootDirectory, key);
             if (!path.EndsWith(".xnb"))
                 path += ".xnb";
 
diff --git a/src/SMAPI/Framework/ContentCore.cs b/src/SMAPI/Framework/SContentManager.cs
index 80fedd6c..8f008041 100644
--- a/src/SMAPI/Framework/ContentCore.cs
+++ b/src/SMAPI/Framework/SContentManager.cs
@@ -5,8 +5,6 @@ using System.Diagnostics.Contracts;
 using System.Globalization;
 using System.IO;
 using System.Linq;
-using System.Reflection;
-using System.Threading;
 using Microsoft.Xna.Framework;
 using Microsoft.Xna.Framework.Content;
 using Microsoft.Xna.Framework.Graphics;
@@ -14,110 +12,186 @@ using StardewModdingAPI.Framework.Content;
 using StardewModdingAPI.Framework.Exceptions;
 using StardewModdingAPI.Framework.Reflection;
 using StardewModdingAPI.Framework.Utilities;
-using StardewModdingAPI.Metadata;
 using StardewValley;
 
 namespace StardewModdingAPI.Framework
 {
-    /// <summary>A thread-safe content handler which loads assets with support for mod injection and editing.</summary>
-    /// <remarks>
-    /// This is the centralised content logic which manages all game assets. The game and mods don't use this class
-    /// directly; instead they use one of several <see cref="ContentManagerShim"/> instances, which proxy requests to
-    /// this class. That ensures that when the game disposes one content manager, the others can continue unaffected.
-    /// That notably requires this class to be thread-safe, since the content managers can be disposed asynchronously.
-    /// 
-    /// Note that assets in the cache have two identifiers: the asset name (like "bundles") and key (like "bundles.pt-BR").
-    /// For English and non-translatable assets, these have the same value. The underlying cache only knows about asset
-    /// keys, and the game and mods only know about asset names. The content manager handles resolving them.
-    /// </remarks>
-    internal class ContentCore : IDisposable
+    /// <summary>A minimal content manager which defers to SMAPI's core content logic.</summary>
+    internal class SContentManager : LocalizedContentManager
     {
         /*********
         ** Properties
         *********/
-        /// <summary>The underlying content manager.</summary>
-        private readonly LocalizedContentManager Content;
-
-        /// <summary>Encapsulates monitoring and logging.</summary>
-        private readonly IMonitor Monitor;
+        /// <summary>The central coordinator which manages content managers.</summary>
+        private readonly ContentCoordinator Coordinator;
 
         /// <summary>The underlying asset cache.</summary>
         private readonly ContentCache Cache;
 
+        /// <summary>Encapsulates monitoring and logging.</summary>
+        private readonly IMonitor Monitor;
+
         /// <summary>A lookup which indicates whether the asset is localisable (i.e. the filename contains the locale), if previously loaded.</summary>
         private readonly IDictionary<string, bool> IsLocalisableLookup;
 
         /// <summary>The language enum values indexed by locale code.</summary>
         private readonly IDictionary<string, LocalizedContentManager.LanguageCode> LanguageCodes;
 
-        /// <summary>Provides metadata for core game assets.</summary>
-        private readonly CoreAssetPropagator CoreAssets;
-
         /// <summary>The assets currently being intercepted by <see cref="IAssetLoader"/> instances. This is used to prevent infinite loops when a loader loads a new asset.</summary>
         private readonly ContextHash<string> AssetsBeingLoaded = new ContextHash<string>();
 
-        /// <summary>A lookup of the content managers which loaded each asset.</summary>
-        private readonly IDictionary<string, HashSet<ContentManager>> ContentManagersByAssetKey = new Dictionary<string, HashSet<ContentManager>>();
-
         /// <summary>The path prefix for assets in mod folders.</summary>
         private readonly string ModContentPrefix;
 
-        /// <summary>A lock used to prevents concurrent changes to the cache while data is being read.</summary>
-        private readonly ReaderWriterLockSlim Lock = new ReaderWriterLockSlim(LockRecursionPolicy.SupportsRecursion);
+        /// <summary>Interceptors which provide the initial versions of matching assets.</summary>
+        private IDictionary<IModMetadata, IList<IAssetLoader>> Loaders => this.Coordinator.Loaders;
+
+        /// <summary>Interceptors which edit matching assets after they're loaded.</summary>
+        private IDictionary<IModMetadata, IList<IAssetEditor>> Editors => this.Coordinator.Editors;
 
 
         /*********
         ** Accessors
         *********/
-        /// <summary>The current language as a constant.</summary>
-        public LocalizedContentManager.LanguageCode Language => this.Content.GetCurrentLanguage();
+        /// <summary>A name for the mod manager. Not guaranteed to be unique.</summary>
+        public string Name { get; }
 
-        /// <summary>Interceptors which provide the initial versions of matching assets.</summary>
-        public IDictionary<IModMetadata, IList<IAssetLoader>> Loaders { get; } = new Dictionary<IModMetadata, IList<IAssetLoader>>();
+        /// <summary>Whether this content manager is wrapped around a mod folder.</summary>
+        public bool IsModFolder { get; }
 
-        /// <summary>Interceptors which edit matching assets after they're loaded.</summary>
-        public IDictionary<IModMetadata, IList<IAssetEditor>> Editors { get; } = new Dictionary<IModMetadata, IList<IAssetEditor>>();
+        /// <summary>The current language as a constant.</summary>
+        public LocalizedContentManager.LanguageCode Language => this.GetCurrentLanguage();
 
         /// <summary>The absolute path to the <see cref="ContentManager.RootDirectory"/>.</summary>
-        public string FullRootDirectory => Path.Combine(Constants.ExecutionPath, this.Content.RootDirectory);
+        public string FullRootDirectory => Path.Combine(Constants.ExecutionPath, this.RootDirectory);
+
 
         /*********
         ** Public methods
         *********/
-        /****
-        ** Constructor
-        ****/
         /// <summary>Construct an instance.</summary>
+        /// <param name="name">A name for the mod manager. Not guaranteed to be unique.</param>
         /// <param name="serviceProvider">The service provider to use to locate services.</param>
         /// <param name="rootDirectory">The root directory to search for content.</param>
         /// <param name="currentCulture">The current culture for which to localise content.</param>
+        /// <param name="coordinator">The central coordinator which manages content managers.</param>
         /// <param name="monitor">Encapsulates monitoring and logging.</param>
         /// <param name="reflection">Simplifies access to private code.</param>
-        public ContentCore(IServiceProvider serviceProvider, string rootDirectory, CultureInfo currentCulture, IMonitor monitor, Reflector reflection)
+        /// <param name="isModFolder">Whether this content manager is wrapped around a mod folder.</param>
+        public SContentManager(string name, IServiceProvider serviceProvider, string rootDirectory, CultureInfo currentCulture, ContentCoordinator coordinator, IMonitor monitor, Reflector reflection, bool isModFolder)
+                : base(serviceProvider, rootDirectory, currentCulture)
         {
             // init
+            this.Name = name;
+            this.IsModFolder = isModFolder;
+            this.Coordinator = coordinator ?? throw new ArgumentNullException(nameof(coordinator));
+            this.Cache = new ContentCache(this, reflection);
             this.Monitor = monitor ?? throw new ArgumentNullException(nameof(monitor));
-            this.Content = new LocalizedContentManager(serviceProvider, rootDirectory, currentCulture);
-            this.Cache = new ContentCache(this.Content, reflection);
-            this.ModContentPrefix = this.GetAssetNameFromFilePath(Constants.ModPath);
+            this.ModContentPrefix = this.GetAssetNameFromFilePath(Constants.ModPath, ContentSource.GameContent);
 
             // get asset data
-            this.CoreAssets = new CoreAssetPropagator(this.NormaliseAssetName, reflection);
             this.LanguageCodes = this.GetKeyLocales().ToDictionary(p => p.Value, p => p.Key, StringComparer.InvariantCultureIgnoreCase);
-            this.IsLocalisableLookup = reflection.GetField<IDictionary<string, bool>>(this.Content, "_localizedAsset").GetValue();
+            this.IsLocalisableLookup = reflection.GetField<IDictionary<string, bool>>(this, "_localizedAsset").GetValue();
+
         }
 
-        /// <summary>Get a new content manager which defers loading to the content core.</summary>
-        /// <param name="name">The content manager's name for logs (if any).</param>
-        /// <param name="rootDirectory">The root directory to search for content (or <c>null</c>. for the default)</param>
-        public ContentManagerShim CreateContentManager(string name, string rootDirectory = null)
+        /// <summary>Load an asset that has been processed by the content pipeline.</summary>
+        /// <typeparam name="T">The type of asset to load.</typeparam>
+        /// <param name="assetName">The asset path relative to the loader root directory, not including the <c>.xnb</c> extension.</param>
+        public override T Load<T>(string assetName)
         {
-            return new ContentManagerShim(this, name, this.Content.ServiceProvider, rootDirectory ?? this.Content.RootDirectory, this.Content.CurrentCulture);
+            return this.Load<T>(assetName, LocalizedContentManager.CurrentLanguageCode);
+        }
+
+        /// <summary>Load an asset that has been processed by the content pipeline.</summary>
+        /// <typeparam name="T">The type of asset to load.</typeparam>
+        /// <param name="assetName">The asset path relative to the loader root directory, not including the <c>.xnb</c> extension.</param>
+        /// <param name="language">The language code for which to load content.</param>
+        public override T Load<T>(string assetName, LanguageCode language)
+        {
+            // normalise asset key
+            this.AssertValidAssetKeyFormat(assetName);
+            assetName = this.NormaliseAssetName(assetName);
+
+            // load game content
+            if (!this.IsModFolder && !assetName.StartsWith(this.ModContentPrefix))
+                return this.LoadImpl<T>(assetName, language);
+
+            // load mod content
+            SContentLoadException GetContentError(string reasonPhrase) => new SContentLoadException($"Failed loading content asset '{assetName}': {reasonPhrase}");
+            try
+            {
+                // try cache
+                if (this.IsLoaded(assetName))
+                    return this.LoadImpl<T>(assetName, language);
+
+                // get file
+                FileInfo file = this.GetModFile(assetName);
+                if (!file.Exists)
+                    throw GetContentError("the specified path doesn't exist.");
+
+                // load content
+                switch (file.Extension.ToLower())
+                {
+                    // XNB file
+                    case ".xnb":
+                        return this.LoadImpl<T>(assetName, language);
+
+                    // unpacked map
+                    case ".tbin":
+                        throw GetContentError($"can't read unpacked map file '{assetName}' directly from the underlying content manager. It must be loaded through the mod's {typeof(IModHelper)}.{nameof(IModHelper.Content)} helper.");
+
+                    // unpacked image
+                    case ".png":
+                        // validate
+                        if (typeof(T) != typeof(Texture2D))
+                            throw GetContentError($"can't read file with extension '{file.Extension}' as type '{typeof(T)}'; must be type '{typeof(Texture2D)}'.");
+
+                        // fetch & cache
+                        using (FileStream stream = File.OpenRead(file.FullName))
+                        {
+                            Texture2D texture = Texture2D.FromStream(Game1.graphics.GraphicsDevice, stream);
+                            texture = this.PremultiplyTransparency(texture);
+                            this.Inject(assetName, texture);
+                            return (T)(object)texture;
+                        }
+
+                    default:
+                        throw GetContentError($"unknown file extension '{file.Extension}'; must be one of '.png', '.tbin', or '.xnb'.");
+                }
+            }
+            catch (Exception ex) when (!(ex is SContentLoadException))
+            {
+                if (ex.GetInnermostException() is DllNotFoundException dllEx && dllEx.Message == "libgdiplus.dylib")
+                    throw GetContentError("couldn't find libgdiplus, which is needed to load mod images. Make sure Mono is installed and you're running the game through the normal launcher.");
+                throw new SContentLoadException($"The content manager failed loading content asset '{assetName}'.", ex);
+            }
+        }
+
+        /// <summary>Load the base asset without localisation.</summary>
+        /// <typeparam name="T">The type of asset to load.</typeparam>
+        /// <param name="assetName">The asset path relative to the loader root directory, not including the <c>.xnb</c> extension.</param>
+        public override T LoadBase<T>(string assetName)
+        {
+            return this.Load<T>(assetName, LanguageCode.en);
+        }
+
+        /// <summary>Inject an asset into the cache.</summary>
+        /// <typeparam name="T">The type of asset to inject.</typeparam>
+        /// <param name="assetName">The asset path relative to the loader root directory, not including the <c>.xnb</c> extension.</param>
+        /// <param name="value">The asset value.</param>
+        public void Inject<T>(string assetName, T value)
+        {
+            assetName = this.NormaliseAssetName(assetName);
+            this.Cache[assetName] = value;
+        }
+
+        /// <summary>Create a new content manager for temporary use.</summary>
+        public override LocalizedContentManager CreateTemporary()
+        {
+            return this.Coordinator.CreateContentManager("(temporary)", isModFolder: false);
         }
 
-        /****
-        ** Asset key/name handling</