reorganise repo structure

25 files changed, 2071 insertions, 0 deletions

diff --git a/src/SMAPI/Framework/ModLoading/AssemblyDefinitionResolver.cs b/src/SMAPI/Framework/ModLoading/AssemblyDefinitionResolver.cs
new file mode 100644
index 00000000..4378798c
--- /dev/null
+++ b/src/SMAPI/Framework/ModLoading/AssemblyDefinitionResolver.cs
@@ -0,0 +1,61 @@
+using System.Collections.Generic;
+using Mono.Cecil;
+
+namespace StardewModdingAPI.Framework.ModLoading
+{
+    /// <summary>A minimal assembly definition resolver which resolves references to known assemblies.</summary>
+    internal class AssemblyDefinitionResolver : DefaultAssemblyResolver
+    {
+        /*********
+        ** Properties
+        *********/
+        /// <summary>The known assemblies.</summary>
+        private readonly IDictionary<string, AssemblyDefinition> Loaded = new Dictionary<string, AssemblyDefinition>();
+
+
+        /*********
+        ** Public methods
+        *********/
+        /// <summary>Add known assemblies to the resolver.</summary>
+        /// <param name="assemblies">The known assemblies.</param>
+        public void Add(params AssemblyDefinition[] assemblies)
+        {
+            foreach (AssemblyDefinition assembly in assemblies)
+            {
+                this.Loaded[assembly.Name.Name] = assembly;
+                this.Loaded[assembly.Name.FullName] = assembly;
+            }
+        }
+
+        /// <summary>Resolve an assembly reference.</summary>
+        /// <param name="name">The assembly name.</param>
+        public override AssemblyDefinition Resolve(AssemblyNameReference name) => this.ResolveName(name.Name) ?? base.Resolve(name);
+
+        /// <summary>Resolve an assembly reference.</summary>
+        /// <param name="name">The assembly name.</param>
+        /// <param name="parameters">The assembly reader parameters.</param>
+        public override AssemblyDefinition Resolve(AssemblyNameReference name, ReaderParameters parameters) => this.ResolveName(name.Name) ?? base.Resolve(name, parameters);
+
+        /// <summary>Resolve an assembly reference.</summary>
+        /// <param name="fullName">The assembly full name (including version, etc).</param>
+        public override AssemblyDefinition Resolve(string fullName) => this.ResolveName(fullName) ?? base.Resolve(fullName);
+
+        /// <summary>Resolve an assembly reference.</summary>
+        /// <param name="fullName">The assembly full name (including version, etc).</param>
+        /// <param name="parameters">The assembly reader parameters.</param>
+        public override AssemblyDefinition Resolve(string fullName, ReaderParameters parameters) => this.ResolveName(fullName) ?? base.Resolve(fullName, parameters);
+
+
+        /*********
+        ** Private methods
+        *********/
+        /// <summary>Resolve a known assembly definition based on its short or full name.</summary>
+        /// <param name="name">The assembly's short or full name.</param>
+        private AssemblyDefinition ResolveName(string name)
+        {
+            return this.Loaded.ContainsKey(name)
+                ? this.Loaded[name]
+                : null;
+        }
+    }
+}
diff --git a/src/SMAPI/Framework/ModLoading/AssemblyLoadStatus.cs b/src/SMAPI/Framework/ModLoading/AssemblyLoadStatus.cs
new file mode 100644
index 00000000..11be19fc
--- /dev/null
+++ b/src/SMAPI/Framework/ModLoading/AssemblyLoadStatus.cs
@@ -0,0 +1,15 @@
+namespace StardewModdingAPI.Framework.ModLoading
+{
+    /// <summary>Indicates the result of an assembly load.</summary>
+    internal enum AssemblyLoadStatus
+    {
+        /// <summary>The assembly was loaded successfully.</summary>
+        Okay = 1,
+
+        /// <summary>The assembly could not be loaded.</summary>
+        Failed = 2,
+
+        /// <summary>The assembly is already loaded.</summary>
+        AlreadyLoaded = 3
+    }
+}
diff --git a/src/SMAPI/Framework/ModLoading/AssemblyLoader.cs b/src/SMAPI/Framework/ModLoading/AssemblyLoader.cs
new file mode 100644
index 00000000..1e3c4a05
--- /dev/null
+++ b/src/SMAPI/Framework/ModLoading/AssemblyLoader.cs
@@ -0,0 +1,333 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Reflection;
+using Mono.Cecil;
+using Mono.Cecil.Cil;
+using StardewModdingAPI.Framework.Exceptions;
+using StardewModdingAPI.Metadata;
+
+namespace StardewModdingAPI.Framework.ModLoading
+{
+    /// <summary>Preprocesses and loads mod assemblies.</summary>
+    internal class AssemblyLoader
+    {
+        /*********
+        ** Properties
+        *********/
+        /// <summary>Metadata for mapping assemblies to the current platform.</summary>
+        private readonly PlatformAssemblyMap AssemblyMap;
+
+        /// <summary>A type => assembly lookup for types which should be rewritten.</summary>
+        private readonly IDictionary<string, Assembly> TypeAssemblies;
+
+        /// <summary>Encapsulates monitoring and logging.</summary>
+        private readonly IMonitor Monitor;
+
+        /// <summary>Whether to enable developer mode logging.</summary>
+        private readonly bool IsDeveloperMode;
+
+
+        /*********
+        ** Public methods
+        *********/
+        /// <summary>Construct an instance.</summary>
+        /// <param name="targetPlatform">The current game platform.</param>
+        /// <param name="monitor">Encapsulates monitoring and logging.</param>
+        /// <param name="isDeveloperMode">Whether to enable developer mode logging.</param>
+        public AssemblyLoader(Platform targetPlatform, IMonitor monitor, bool isDeveloperMode)
+        {
+            this.Monitor = monitor;
+            this.IsDeveloperMode = isDeveloperMode;
+            this.AssemblyMap = Constants.GetAssemblyMap(targetPlatform);
+
+            // generate type => assembly lookup for types which should be rewritten
+            this.TypeAssemblies = new Dictionary<string, Assembly>();
+            foreach (Assembly assembly in this.AssemblyMap.Targets)
+            {
+                ModuleDefinition module = this.AssemblyMap.TargetModules[assembly];
+                foreach (TypeDefinition type in module.GetTypes())
+                {
+                    if (!type.IsPublic)
+                        continue; // no need to rewrite
+                    if (type.Namespace.Contains("<"))
+                        continue; // ignore assembly metadata
+                    this.TypeAssemblies[type.FullName] = assembly;
+                }
+            }
+        }
+
+        /// <summary>Preprocess and load an assembly.</summary>
+        /// <param name="mod">The mod for which the assembly is being loaded.</param>
+        /// <param name="assemblyPath">The assembly file path.</param>
+        /// <param name="assumeCompatible">Assume the mod is compatible, even if incompatible code is detected.</param>
+        /// <returns>Returns the rewrite metadata for the preprocessed assembly.</returns>
+        /// <exception cref="IncompatibleInstructionException">An incompatible CIL instruction was found while rewriting the assembly.</exception>
+        public Assembly Load(IModMetadata mod, string assemblyPath, bool assumeCompatible)
+        {
+            // get referenced local assemblies
+            AssemblyParseResult[] assemblies;
+            {
+                AssemblyDefinitionResolver resolver = new AssemblyDefinitionResolver();
+                HashSet<string> visitedAssemblyNames = new HashSet<string>(AppDomain.CurrentDomain.GetAssemblies().Select(p => p.GetName().Name)); // don't try loading assemblies that are already loaded
+                assemblies = this.GetReferencedLocalAssemblies(new FileInfo(assemblyPath), visitedAssemblyNames, resolver).ToArray();
+            }
+
+            // validate load
+            if (!assemblies.Any() || assemblies[0].Status == AssemblyLoadStatus.Failed)
+            {
+                throw new SAssemblyLoadFailedException(!File.Exists(assemblyPath)
+                    ? $"Could not load '{assemblyPath}' because it doesn't exist."
+                    : $"Could not load '{assemblyPath}'."
+                );
+            }
+            if (assemblies.Last().Status == AssemblyLoadStatus.AlreadyLoaded) // mod assembly is last in dependency order
+                throw new SAssemblyLoadFailedException($"Could not load '{assemblyPath}' because it was already loaded. Do you have two copies of this mod?");
+
+            // rewrite & load assemblies in leaf-to-root order
+            bool oneAssembly = assemblies.Length == 1;
+            Assembly lastAssembly = null;
+            HashSet<string> loggedMessages = new HashSet<string>();
+            foreach (AssemblyParseResult assembly in assemblies)
+            {
+                if (assembly.Status == AssemblyLoadStatus.AlreadyLoaded)
+                    continue;
+
+                bool changed = this.RewriteAssembly(mod, assembly.Definition, assumeCompatible, loggedMessages, logPrefix: "   ");
+                if (changed)
+                {
+                    if (!oneAssembly)
+                        this.Monitor.Log($"   Loading {assembly.File.Name} (rewritten in memory)...", LogLevel.Trace);
+                    using (MemoryStream outStream = new MemoryStream())
+                    {
+                        assembly.Definition.Write(outStream);
+                        byte[] bytes = outStream.ToArray();
+                        lastAssembly = Assembly.Load(bytes);
+                    }
+                }
+                else
+                {
+                    if (!oneAssembly)
+                        this.Monitor.Log($"   Loading {assembly.File.Name}...", LogLevel.Trace);
+                    lastAssembly = Assembly.UnsafeLoadFrom(assembly.File.FullName);
+                }
+            }
+
+            // last assembly loaded is the root
+            return lastAssembly;
+        }
+
+        /// <summary>Resolve an assembly by its name.</summary>
+        /// <param name="name">The assembly name.</param>
+        /// <remarks>
+        /// This implementation returns the first loaded assembly which matches the short form of
+        /// the assembly name, to resolve assembly resolution issues when rewriting
+        /// assemblies (especially with Mono). Since this is meant to be called on <see cref="AppDomain.AssemblyResolve"/>,
+        /// the implicit assumption is that loading the exact assembly failed.
+        /// </remarks>
+        public Assembly ResolveAssembly(string name)
+        {
+            string shortName = name.Split(new[] { ',' }, 2).First(); // get simple name (without version and culture)
+            return AppDomain.CurrentDomain
+                .GetAssemblies()
+                .FirstOrDefault(p => p.GetName().Name == shortName);
+        }
+
+
+        /*********
+        ** Private methods
+        *********/
+        /****
+        ** Assembly parsing
+        ****/
+        /// <summary>Get a list of referenced local assemblies starting from the mod assembly, ordered from leaf to root.</summary>
+        /// <param name="file">The assembly file to load.</param>
+        /// <param name="visitedAssemblyNames">The assembly names that should be skipped.</param>
+        /// <param name="assemblyResolver">A resolver which resolves references to known assemblies.</param>
+        /// <returns>Returns the rewrite metadata for the preprocessed assembly.</returns>
+        private IEnumerable<AssemblyParseResult> GetReferencedLocalAssemblies(FileInfo file, HashSet<string> visitedAssemblyNames, IAssemblyResolver assemblyResolver)
+        {
+            // validate
+            if (file.Directory == null)
+                throw new InvalidOperationException($"Could not get directory from file path '{file.FullName}'.");
+            if (!file.Exists)
+                yield break; // not a local assembly
+
+            // read assembly
+            byte[] assemblyBytes = File.ReadAllBytes(file.FullName);
+            AssemblyDefinition assembly;
+            using (Stream readStream = new MemoryStream(assemblyBytes))
+                assembly = AssemblyDefinition.ReadAssembly(readStream, new ReaderParameters(ReadingMode.Deferred) { AssemblyResolver = assemblyResolver });
+
+            // skip if already visited
+            if (visitedAssemblyNames.Contains(assembly.Name.Name))
+                yield return new AssemblyParseResult(file, null, AssemblyLoadStatus.AlreadyLoaded);
+            visitedAssemblyNames.Add(assembly.Name.Name);
+
+            // yield referenced assemblies
+            foreach (AssemblyNameReference dependency in assembly.MainModule.AssemblyReferences)
+            {
+                FileInfo dependencyFile = new FileInfo(Path.Combine(file.Directory.FullName, $"{dependency.Name}.dll"));
+                foreach (AssemblyParseResult result in this.GetReferencedLocalAssemblies(dependencyFile, visitedAssemblyNames, assemblyResolver))
+                    yield return result;
+            }
+
+            // yield assembly
+            yield return new AssemblyParseResult(file, assembly, AssemblyLoadStatus.Okay);
+        }
+
+        /****
+        ** Assembly rewriting
+        ****/
+        /// <summary>Rewrite the types referenced by an assembly.</summary>
+        /// <param name="mod">The mod for which the assembly is being loaded.</param>
+        /// <param name="assembly">The assembly to rewrite.</param>
+        /// <param name="assumeCompatible">Assume the mod is compatible, even if incompatible code is detected.</param>
+        /// <param name="loggedMessages">The messages that have already been logged for this mod.</param>
+        /// <param name="logPrefix">A string to prefix to log messages.</param>
+        /// <returns>Returns whether the assembly was modified.</returns>
+        /// <exception cref="IncompatibleInstructionException">An incompatible CIL instruction was found while rewriting the assembly.</exception>
+        private bool RewriteAssembly(IModMetadata mod, AssemblyDefinition assembly, bool assumeCompatible, HashSet<string> loggedMessages, string logPrefix)
+        {
+            ModuleDefinition module = assembly.MainModule;
+            string filename = $"{assembly.Name.Name}.dll";
+
+            // swap assembly references if needed (e.g. XNA => MonoGame)
+            bool platformChanged = false;
+            for (int i = 0; i < module.AssemblyReferences.Count; i++)
+            {
+                // remove old assembly reference
+                if (this.AssemblyMap.RemoveNames.Any(name => module.AssemblyReferences[i].Name == name))
+                {
+                    this.Monitor.LogOnce(loggedMessages, $"{logPrefix}Rewriting {filename} for OS...");
+                    platformChanged = true;
+                    module.AssemblyReferences.RemoveAt(i);
+                    i--;
+                }
+            }
+            if (platformChanged)
+            {
+                // add target assembly references
+                foreach (AssemblyNameReference target in this.AssemblyMap.TargetReferences.Values)
+                    module.AssemblyReferences.Add(target);
+
+                // rewrite type scopes to use target assemblies
+                IEnumerable<TypeReference> typeReferences = module.GetTypeReferences().OrderBy(p => p.FullName);
+                foreach (TypeReference type in typeReferences)
+                    this.ChangeTypeScope(type);
+            }
+
+            // find (and optionally rewrite) incompatible instructions
+            bool anyRewritten = false;
+            IInstructionHandler[] handlers = new InstructionMetadata().GetHandlers().ToArray();
+            foreach (MethodDefinition method in this.GetMethods(module))
+            {
+                // check method definition
+                foreach (IInstructionHandler handler in handlers)
+                {
+                    InstructionHandleResult result = handler.Handle(module, method, this.AssemblyMap, platformChanged);
+                    this.ProcessInstructionHandleResult(mod, handler, result, loggedMessages, logPrefix, assumeCompatible, filename);
+                    if (result == InstructionHandleResult.Rewritten)
+                        anyRewritten = true;
+                }
+
+                // check CIL instructions
+                ILProcessor cil = method.Body.GetILProcessor();
+                foreach (Instruction instruction in cil.Body.Instructions.ToArray())
+                {
+                    foreach (IInstructionHandler handler in handlers)
+                    {
+                        InstructionHandleResult result = handler.Handle(module, cil, instruction, this.AssemblyMap, platformChanged);
+                        this.ProcessInstructionHandleResult(mod, handler, result, loggedMessages, logPrefix, assumeCompatible, filename);
+                        if (result == InstructionHandleResult.Rewritten)
+                            anyRewritten = true;
+                    }
+                }
+            }
+
+            return platformChanged || anyRewritten;
+        }
+
+        /// <summary>Process the result from an instruction handler.</summary>
+        /// <param name="mod">The mod being analysed.</param>
+        /// <param name="handler">The instruction handler.</param>
+        /// <param name="result">The result returned by the handler.</param>
+        /// <param name="loggedMessages">The messages already logged for the current mod.</param>
+        /// <param name="assumeCompatible">Assume the mod is compatible, even if incompatible code is detected.</param>
+        /// <param name="logPrefix">A string to prefix to log messages.</param>
+        /// <param name="filename">The assembly filename for log messages.</param>
+        private void ProcessInstructionHandleResult(IModMetadata mod, IInstructionHandler handler, InstructionHandleResult result, HashSet<string> loggedMessages, string logPrefix, bool assumeCompatible, string filename)
+        {
+            switch (result)
+            {
+                case InstructionHandleResult.Rewritten:
+                    this.Monitor.LogOnce(loggedMessages, $"{logPrefix}Rewrote {filename} to fix {handler.NounPhrase}...");
+                    break;
+
+                case InstructionHandleResult.NotCompatible:
+                    if (!assumeCompatible)
+                        throw new IncompatibleInstructionException(handler.NounPhrase, $"Found an incompatible CIL instruction ({handler.NounPhrase}) while loading assembly {filename}.");
+                    this.Monitor.LogOnce(loggedMessages, $"{logPrefix}Found an incompatible CIL instruction ({handler.NounPhrase}) while loading assembly {filename}, but SMAPI is configured to allow it anyway. The mod may crash or behave unexpectedly.", LogLevel.Warn);
+                    break;
+
+                case InstructionHandleResult.DetectedGamePatch:
+                    this.Monitor.LogOnce(loggedMessages, $"{logPrefix}Detected game patcher ({handler.NounPhrase}) in assembly {filename}.");
+                    this.Monitor.LogOnce(loggedMessages, $"{mod.DisplayName} patches the game, which may impact game stability. If you encounter problems, try removing this mod first.", LogLevel.Warn);
+                    break;
+
+                case InstructionHandleResult.DetectedSaveSerialiser:
+                    this.Monitor.LogOnce(loggedMessages, $"{logPrefix}Detected possible save serialiser change ({handler.NounPhrase}) in assembly {filename}.");
+                    this.Monitor.LogOnce(loggedMessages, $"{mod.DisplayName} seems to change the save serialiser. It may change your saves in such a way that they won't work without this mod in the future.", LogLevel.Warn);
+                    break;
+
+                case InstructionHandleResult.DetectedDynamic:
+                    this.Monitor.LogOnce(loggedMessages, $"{logPrefix}Detected 'dynamic' keyword ({handler.NounPhrase}) in assembly {filename}.");
+                    this.Monitor.LogOnce(loggedMessages, $"{mod.DisplayName} uses the 'dynamic' keyword, which isn't compatible with Stardew Valley on Linux or Mac.",
+#if SMAPI_FOR_WINDOWS
+                        this.IsDeveloperMode ? LogLevel.Warn : LogLevel.Debug
+#else
+                        LogLevel.Warn
+#endif
+                    );
+                    break;
+
+                case InstructionHandleResult.None:
+                    break;
+
+                default:
+                    throw new NotSupportedException($"Unrecognised instruction handler result '{result}'.");
+            }
+        }
+
+        /// <summary>Get the correct reference to use for compatibility with the current platform.</summary>
+        /// <param name="type">The type reference to rewrite.</param>
+        private void ChangeTypeScope(TypeReference type)
+        {
+            // check skip conditions
+            if (type == null || type.FullName.StartsWith("System."))
+                return;
+
+            // get assembly
+            if (!this.TypeAssemblies.TryGetValue(type.FullName, out Assembly assembly))
+                return;
+
+            // replace scope
+            AssemblyNameReference assemblyRef = this.AssemblyMap.TargetReferences[assembly];
+            type.Scope = assemblyRef;
+        }
+
+        /// <summary>Get all methods in a module.</summary>
+        /// <param name="module">The module to search.</param>
+        private IEnumerable<MethodDefinition> GetMethods(ModuleDefinition module)
+        {
+            return (
+                from type in module.GetTypes()
+                where type.HasMethods
+                from method in type.Methods
+                where method.HasBody
+                select method
+            );
+        }
+    }
+}
diff --git a/src/SMAPI/Framework/ModLoading/AssemblyParseResult.cs b/src/SMAPI/Framework/ModLoading/AssemblyParseResult.cs
new file mode 100644
index 00000000..b56a776c
--- /dev/null
+++ b/src/SMAPI/Framework/ModLoading/AssemblyParseResult.cs
@@ -0,0 +1,36 @@
+using System.IO;
+using Mono.Cecil;
+
+namespace StardewModdingAPI.Framework.ModLoading
+{
+    /// <summary>Metadata about a parsed assembly definition.</summary>
+    internal class AssemblyParseResult
+    {
+        /*********
+        ** Accessors
+        *********/
+        /// <summary>The original assembly file.</summary>
+        public readonly FileInfo File;
+
+        /// <summary>The assembly definition.</summary>
+        public readonly AssemblyDefinition Definition;
+
+        /// <summary>The result of the assembly load.</summary>
+        public AssemblyLoadStatus Status;
+
+
+        /*********
+        ** Public methods
+        *********/
+        /// <summary>Construct an instance.</summary>
+        /// <param name="file">The original assembly file.</param>
+        /// <param name="assembly">The assembly definition.</param>
+        /// <param name="status">The result of the assembly load.</param>
+        public AssemblyParseResult(FileInfo file, AssemblyDefinition assembly, AssemblyLoadStatus status)
+        {
+            this.File = file;
+            this.Definition = assembly;
+            this.Status = status;
+        }
+    }
+}
diff --git a/src/SMAPI/Framework/ModLoading/Finders/EventFinder.cs b/src/SMAPI/Framework/ModLoading/Finders/EventFinder.cs
new file mode 100644
index 00000000..e4beb7a9
--- /dev/null
+++ b/src/SMAPI/Framework/ModLoading/Finders/EventFinder.cs
@@ -0,0 +1,82 @@
+using Mono.Cecil;
+using Mono.Cecil.Cil;
+
+namespace StardewModdingAPI.Framework.ModLoading.Finders
+{
+    /// <summary>Finds incompatible CIL instructions that reference a given event.</summary>
+    internal class EventFinder : IInstructionHandler
+    {
+        /*********
+        ** Properties
+        *********/
+        /// <summary>The full type name for which to find references.</summary>
+        private readonly string FullTypeName;
+
+        /// <summary>The event name for which to find references.</summary>
+        private readonly string EventName;
+
+        /// <summary>The result to return for matching instructions.</summary>
+        private readonly InstructionHandleResult Result;
+
+
+        /*********
+        ** Accessors
+        *********/
+        /// <summary>A brief noun phrase indicating what the instruction finder matches.</summary>
+        public string NounPhrase { get; }
+
+
+        /*********
+        ** Public methods
+        *********/
+        /// <summary>Construct an instance.</summary>
+        /// <param name="fullTypeName">The full type name for which to find references.</param>
+        /// <param name="eventName">The event name for which to find references.</param>
+        /// <param name="result">The result to return for matching instructions.</param>
+        public EventFinder(string fullTypeName, string eventName, InstructionHandleResult result)
+        {
+            this.FullTypeName = fullTypeName;
+            this.EventName = eventName;
+            this.Result = result;
+            this.NounPhrase = $"{fullTypeName}.{eventName} event";
+        }
+
+        /// <summary>Perform the predefined logic for a method if applicable.</summary>
+        /// <param name="module">The assembly module containing the instruction.</param>
+        /// <param name="method">The method definition containing the instruction.</param>
+        /// <param name="assemblyMap">Metadata for mapping assemblies to the current platform.</param>
+        /// <param name="platformChanged">Whether the mod was compiled on a different platform.</param>
+        public virtual InstructionHandleResult Handle(ModuleDefinition module, MethodDefinition method, PlatformAssemblyMap assemblyMap, bool platformChanged)
+        {
+            return InstructionHandleResult.None;
+        }
+
+        /// <summary>Perform the predefined logic for an instruction if applicable.</summary>
+        /// <param name="module">The assembly module containing the instruction.</param>
+        /// <param name="cil">The CIL processor.</param>
+        /// <param name="instruction">The instruction to handle.</param>
+        /// <param name="assemblyMap">Metadata for mapping assemblies to the current platform.</param>
+        /// <param name="platformChanged">Whether the mod was compiled on a different platform.</param>
+        public virtual InstructionHandleResult Handle(ModuleDefinition module, ILProcessor cil, Instruction instruction, PlatformAssemblyMap assemblyMap, bool platformChanged)
+        {
+            return this.IsMatch(instruction)
+                ? this.Result
+                : InstructionHandleResult.None;
+        }
+
+
+        /*********
+        ** Protected methods
+        *********/
+        /// <summary>Get whether a CIL instruction matches.</summary>
+        /// <param name="instruction">The IL instruction.</param>
+        protected bool IsMatch(Instruction instruction)
+        {
+            MethodReference methodRef = RewriteHelper.AsMethodReference(instruction);
+            return
+                methodRef != null
+                && methodRef.DeclaringType.FullName == this.FullTypeName
+                && (methodRef.Name == "add_" + this.EventName || methodRef.Name == "remove_" + this.EventName);
+        }
+    }
+}
diff --git a/src/SMAPI/Framework/ModLoading/Finders/FieldFinder.cs b/src/SMAPI/Framework/ModLoading/Finders/FieldFinder.cs
new file mode 100644
index 00000000..00805815
--- /dev/null
+++ b/src/SMAPI/Framework/ModLoading/Finders/FieldFinder.cs
@@ -0,0 +1,82 @@
+using Mono.Cecil;
+using Mono.Cecil.Cil;
+
+namespace StardewModdingAPI.Framework.ModLoading.Finders
+{
+    /// <summary>Finds incompatible CIL instructions that reference a given field.</summary>
+    internal class FieldFinder : IInstructionHandler
+    {
+        /*********
+        ** Properties
+        *********/
+        /// <summary>The full type name for which to find references.</summary>
+        private readonly string FullTypeName;
+
+        /// <summary>The field name for which to find references.</summary>
+        private readonly string FieldName;
+
+        /// <summary>The result to return for matching instructions.</summary>
+        private readonly InstructionHandleResult Result;
+
+
+        /*********
+        ** Accessors
+        *********/
+        /// <summary>A brief noun phrase indicating what the instruction finder matches.</summary>
+        public string NounPhrase { get; }
+
+
+        /*********
+        ** Public methods
+        *********/
+        /// <summary>Construct an instance.</summary>
+        /// <param name="fullTypeName">The full type name for which to find references.</param>
+        /// <param name="fieldName">The field name for which to find references.</param>
+        /// <param name="result">The result to return for matching instructions.</param>
+        public FieldFinder(string fullTypeName, string fieldName, InstructionHandleResult result)
+        {
+            this.FullTypeName = fullTypeName;
+            this.FieldName = fieldName;
+            this.Result = result;
+            this.NounPhrase = $"{fullTypeName}.{fieldName} field";
+        }
+
+        /// <summary>Perform the predefined logic for a method if applicable.</summary>
+        /// <param name="module">The assembly module containing the instruction.</param>
+        /// <param name="method">The method definition containing the instruction.</param>
+        /// <param name="assemblyMap">Metadata for mapping assemblies to the current platform.</param>
+        /// <param name="platformChanged">Whether the mod was compiled on a different platform.</param>
+        public virtual InstructionHandleResult Handle(ModuleDefinition module, MethodDefinition method, PlatformAssemblyMap assemblyMap, bool platformChanged)
+        {
+            return InstructionHandleResult.None;
+        }
+
+        /// <summary>Perform the predefined logic for an instruction if applicable.</summary>
+        /// <param name="module">The assembly module containing the instruction.</param>
+        /// <param name="cil">The CIL processor.</param>
+        /// <param name="instruction">The instruction to handle.</param>
+        /// <param name="assemblyMap">Metadata for mapping assemblies to the current platform.</param>
+        /// <param name="platformChanged">Whether the mod was compiled on a different platform.</param>
+        public virtual InstructionHandleResult Handle(ModuleDefinition module, ILProcessor cil, Instruction instruction, PlatformAssemblyMap assemblyMap, bool platformChanged)
+        {
+            return this.IsMatch(instruction)
+                ? this.Result
+                : InstructionHandleResult.None;
+        }
+
+
+        /*********
+        ** Protected methods
+        *********/
+        /// <summary>Get whether a CIL instruction matches.</summary>
+        /// <param name="instruction">The IL instruction.</param>
+        protected bool IsMatch(Instruction instruction)
+        {
+            FieldReference fieldRef = RewriteHelper.AsFieldReference(instruction);
+            return
+                fieldRef != null
+                && fieldRef.DeclaringType.FullName == this.FullTypeName
+                && fieldRef.Name == this.FieldName;
+        }
+    }
+}
diff --git a/src/SMAPI/Framework/ModLoading/Finders/MethodFinder.cs b/src/SMAPI/Framework/ModLoading/Finders/MethodFinder.cs
new file mode 100644
index 00000000..5358f181
--- /dev/null
+++ b/src/SMAPI/Framework/ModLoading/Finders/MethodFinder.cs
@@ -0,0 +1,82 @@
+using Mono.Cecil;
+using Mono.Cecil.Cil;
+
+namespace StardewModdingAPI.Framework.ModLoading.Finders
+{
+    /// <summary>Finds incompatible CIL instructions that reference a given method.</summary>
+    internal class MethodFinder : IInstructionHandler
+    {
+        /*********
+        ** Properties
+        *********/
+        /// <summary>The full type name for which to find references.</summary>
+        private readonly string FullTypeName;
+
+        /// <summary>The method name for which to find references.</summary>
+        private readonly string MethodName;
+
+        /// <summary>The result to return for matching instructions.</summary>
+        private readonly InstructionHandleResult Result;
+
+
+        /*********
+        ** Accessors
+        *********/
+        /// <summary>A brief noun phrase indicating what the instruction finder matches.</summary>
+        public string NounPhrase { get; }
+
+
+        /*********
+        ** Public methods
+        *********/
+        /// <summary>Construct an instance.</summary>
+        /// <param name="fullTypeName">The full type name for which to find references.</param>
+        /// <param name="methodName">The method name for which to find references.</param>
+        /// <param name="result">The result to return for matching instructions.</param>
+        public MethodFinder(string fullTypeName, string methodName, InstructionHandleResult result)
+        {
+            this.FullTypeName = fullTypeName;
+            this.MethodName = methodName;
+            this.Result = result;
+            this.NounPhrase = $"{fullTypeName}.{methodName} method";
+        }
+
+        /// <summary>Perform the predefined logic for a method if applicable.</summary>
+        /// <param name="module">The assembly module containing the instruction.</param>
+        /// <param name="method">The method definition containing the instruction.</param>
+        /// <param name="assemblyMap">Metadata for mapping assemblies to the current platform.</param>
+        /// <param name="platformChanged">Whether the mod was compiled on a different platform.</param>
+        public virtual InstructionHandleResult Handle(ModuleDefinition module, MethodDefinition method, PlatformAssemblyMap assemblyMap, bool platformChanged)
+        {
+            return InstructionHandleResult.None;
+        }
+
+        /// <summary>Perform the predefined logic for an instruction if applicable.</summary>
+        /// <param name="module">The assembly module containing the instruction.</param>
+        /// <param name="cil">The CIL processor.</param>
+        /// <param name="instruction">The instruction to handle.</param>
+        /// <param name="assemblyMap">Metadata for mapping assemblies to the current platform.</param>
+        /// <param name="platformChanged">Whether the mod was compiled on a different platform.</param>
+        public InstructionHandleResult Handle(ModuleDefinition module, ILProcessor cil, Instruction instruction, PlatformAssemblyMap assemblyMap, bool platformChanged)
+        {
+            return this.IsMatch(instruction)
+                ? this.Result
+                : InstructionHandleResult.None;
+        }
+
+
+        /*********
+        ** Protected methods
+        *********/
+        /// <summary>Get whether a CIL instruction matches.</summary>
+        /// <param name="instruction">The IL instruction.</param>
+        protected bool IsMatch(Instruction instruction)
+        {
+            MethodReference methodRef = RewriteHelper.AsMethodReference(instruction);
+            return
+                methodRef != null
+                && methodRef.DeclaringType.FullName == this.FullTypeName
+                && methodRef.Name == this.MethodName;
+        }
+    }
+}
diff --git a/src/SMAPI/Framework/ModLoading/Finders/PropertyFinder.cs b/src/SMAPI/Framework/ModLoading/Finders/PropertyFinder.cs
new file mode 100644
index 00000000..e54c86cf
--- /dev/null
+++ b/src/SMAPI/Framework/ModLoading/Finders/PropertyFinder.cs
@@ -0,0 +1,82 @@
+using Mono.Cecil;
+using Mono.Cecil.Cil;
+
+namespace StardewModdingAPI.Framework.ModLoading.Finders
+{
+    /// <summary>Finds incompatible CIL instructions that reference a given property.</summary>
+    internal class PropertyFinder : IInstructionHandler
+    {
+        /*********
+        ** Properties
+        *********/
+        /// <summary>The full type name for which to find references.</summary>
+        private readonly string FullTypeName;
+
+        /// <summary>The property name for which to find references.</summary>
+        private readonly string PropertyName;
+
+        /// <summary>The result to return for matching instructions.</summary>
+        private readonly InstructionHandleResult Result;
+
+
+        /*********
+        ** Accessors
+        *********/
+        /// <summary>A brief noun phrase indicating what the instruction finder matches.</summary>
+        public string NounPhrase { get; }
+
+
+        /*********
+        ** Public methods
+        *********/
+        /// <summary>Construct an instance.</summary>
+        /// <param name="fullTypeName">The full type name for which to find references.</param>
+        /// <param name="propertyName">The property name for which to find references.</param>
+        /// <param name="result">The result to return for matching instructions.</param>
+        public PropertyFinder(string fullTypeName, string propertyName, InstructionHandleResult result)
+        {
+            this.FullTypeName = fullTypeName;
+            this.PropertyName = propertyName;
+            this.Result = result;
+            this.NounPhrase = $"{fullTypeName}.{propertyName} property";
+        }
+
+        /// <summary>Perform the predefined logic for a method if applicable.</summary>
+        /// <param name="module">The assembly module containing the instruction.</param>
+        /// <param name="method">The method definition containing the instruction.</param>
+        /// <param name="assemblyMap">Metadata for mapping assemblies to the current platform.</param>
+        /// <param name="platformChanged">Whether the mod was compiled on a different platform.</param>
+        public virtual InstructionHandleResult Handle(ModuleDefinition module, MethodDefinition method, PlatformAssemblyMap assemblyMap, bool platformChanged)
+        {
+            return InstructionHandleResult.None;
+        }
+
+        /// <summary>Perform the predefined logic for an instruction if applicable.</summary>
+        /// <param name="module">The assembly module containing the instruction.</param>
+        /// <param name="cil">The CIL processor.</param>
+        /// <param name="instruction">The instruction to handle.</param>
+        /// <param name="assemblyMap">Metadata for mapping assemblies to the current platform.</param>
+        /// <param name="platformChanged">Whether the mod was compiled on a different platform.</param>
+        public virtual InstructionHandleResult Handle(ModuleDefinition module, ILProcessor cil, Instruction instruction, PlatformAssemblyMap assemblyMap, bool platformChanged)
+        {
+            return this.IsMatch(instruction)
+                ? this.Result
+                : InstructionHandleResult.None;
+        }
+
+
+        /*********
+        ** Protected methods
+        *********/
+        /// <summary>Get whether a CIL instruction matches.</summary>
+        /// <param name="instruction">The IL instruction.</param>
+        protected bool IsMatch(Instruction instruction)
+        {
+            MethodReference methodRef = RewriteHelper.AsMethodReference(instruction);
+            return
+                methodRef != null
+                && methodRef.DeclaringType.FullName == this.FullTypeName
+                && (methodRef.Name == "get_" + this.PropertyName || methodRef.Name == "set_" + this.PropertyName);
+        }
+    }
+}
diff --git a/src/SMAPI/Framework/ModLoading/Finders/TypeFinder.cs b/src/SMAPI/Framework/ModLoading/Finders/TypeFinder.cs
new file mode 100644
index 00000000..45349def
--- /dev/null
+++ b/src/SMAPI/Framework/ModLoading/Finders/TypeFinder.cs
@@ -0,0 +1,133 @@
+using System.Linq;
+using Mono.Cecil;
+using Mono.Cecil.Cil;
+
+namespace StardewModdingAPI.Framework.ModLoading.Finders
+{
+    /// <summary>Finds incompatible CIL instructions that reference a given type.</summary>
+    internal class TypeFinder : IInstructionHandler
+    {
+        /*********
+        ** Accessors
+        *********/
+        /// <summary>The full type name for which to find references.</summary>
+        private readonly string FullTypeName;
+
+        /// <summary>The result to return for matching instructions.</summary>
+        private readonly InstructionHandleResult Result;
+
+
+        /*********
+        ** Accessors
+        *********/
+        /// <summary>A brief noun phrase indicating what the instruction finder matches.</summary>
+        public string NounPhrase { get; }
+
+
+        /*********
+        ** Public methods
+        *********/
+        /// <summary>Construct an instance.</summary>
+        /// <param name="fullTypeName">The full type name to match.</param>
+        /// <param name="result">The result to return for matching instructions.</param>
+        public TypeFinder(string fullTypeName, InstructionHandleResult result)
+        {
+            this.FullTypeName = fullTypeName;
+            this.Result = result;
+            this.NounPhrase = $"{fullTypeName} type";
+        }
+
+        /// <summary>Perform the predefined logic for a method if applicable.</summary>
+        /// <param name="module">The assembly module containing the instruction.</param>
+        /// <param name="method">The method definition containing the instruction.</param>
+        /// <param name="assemblyMap">Metadata for mapping assemblies to the current platform.</param>
+        /// <param name="platformChanged">Whether the mod was compiled on a different platform.</param>
+        public virtual InstructionHandleResult Handle(ModuleDefinition module, MethodDefinition method, PlatformAssemblyMap assemblyMap, bool platformChanged)
+        {
+            return this.IsMatch(method)
+                ? this.Result
+                : InstructionHandleResult.None;
+        }
+
+        /// <summary>Perform the predefined logic for an instruction if applicable.</summary>
+        /// <param name="module">The assembly module containing the instruction.</param>
+        /// <param name="cil">The CIL processor.</param>
+        /// <param name="instruction">The instruction to handle.</param>
+        /// <param name="assemblyMap">Metadata for mapping assemblies to the current platform.</param>
+        /// <param name="platformChanged">Whether the mod was compiled on a different platform.</param>
+        public virtual InstructionHandleResult Handle(ModuleDefinition module, ILProcessor cil, Instruction instruction, PlatformAssemblyMap assemblyMap, bool platformChanged)
+        {
+            return this.IsMatch(instruction)
+                ? this.Result
+                : InstructionHandleResult.None;
+        }
+
+
+        /*********
+        ** Protected methods
+        *********/
+        /// <summary>Get whether a CIL instruction matches.</summary>
+        /// <param name="method">The method deifnition.</param>
+        protected bool IsMatch(MethodDefinition method)
+        {
+            if (this.IsMatch(method.ReturnType))
+                return true;
+
+            foreach (VariableDefinition variable in method.Body.Variables)
+            {
+                if (this.IsMatch(variable.VariableType))
+                    return true;
+            }
+
+            return false;
+        }
+
+        /// <summary>Get whether a CIL instruction matches.</summary>
+        /// <param name="instruction">The IL instruction.</param>
+        protected bool IsMatch(Instruction instruction)
+        {
+            // field reference
+            FieldReference fieldRef = RewriteHelper.AsFieldReference(instruction);
+            if (fieldRef != null)
+            {
+                return
+                    this.IsMatch(fieldRef.DeclaringType) // field on target class
+                    || this.IsMatch(fieldRef.FieldType); // field value is target class
+            }
+
+            // method reference
+            MethodReference methodRef = RewriteHelper.AsMethodReference(instruction);
+            if (methodRef != null)
+            {
+                return
+                    this.IsMatch(methodRef.DeclaringType) // method on target class
+                    || this.IsMatch(methodRef.ReturnType) // method returns target class
+                    || methodRef.Parameters.Any(p => this.IsMatch(p.ParameterType)); // method parameters
+            }
+
+            return false;
+        }
+
+        /// <summary>Get whether a type reference matches the expected type.</summary>
+        /// <param name="type">The type to check.</param>
+        protected bool IsMatch(TypeReference type)
+        {
+            // root type
+            if (type.FullName == this.FullTypeName)
+                return true;
+
+            // generic arguments
+            if (type is GenericInstanceType genericType)
+            {
+                if (genericType.GenericArguments.Any(this.IsMatch))
+                    return true;
+            }
+
+            // generic parameters (e.g. constraints)
+            if (type.GenericParameters.Any(this.IsMatch))
+                return true;
+
+            return false;
+        }
+    }
+}
diff --git a/src/SMAPI/Framework/ModLoading/IInstructionHandler.cs b/src/SMAPI/Framework/ModLoading/IInstructionHandler.cs
new file mode 100644
index 00000000..8830cc74
--- /dev/null
+++ b/src/SMAPI/Framework/ModLoading/IInstructionHandler.cs
@@ -0,0 +1,34 @@
+using Mono.Cecil;
+using Mono.Cecil.Cil;
+
+namespace StardewModdingAPI.Framework.ModLoading
+{
+    /// <summary>Performs predefined logic for detected CIL instructions.</summary>
+    internal interface IInstructionHandler
+    {
+        /*********
+        ** Accessors
+        *********/
+        /// <summary>A brief noun phrase indicating what the handler matches.</summary>
+        string NounPhrase { get; }
+
+
+        /*********
+        ** Methods
+        *********/
+        /// <summary>Perform the predefined logic for a method if applicable.</summary>
+        /// <param name="module">The assembly module containing the instruction.</param>
+        /// <param name="method">The method definition containing the instruction.</param>
+        /// <param name="assemblyMap">Metadata for mapping assemblies to the current platform.</param>
+        /// <param name="platformChanged">Whether the mod was compiled on a different platform.</param>
+        InstructionHandleResult Handle(ModuleDefinition module, MethodDefinition method, PlatformAssemblyMap assemblyMap, bool platformChanged);
+
+        /// <summary>Perform the predefined logic for an instruction if applicable.</summary>
+        /// <param name="module">The assembly module containing the instruction.</param>
+        /// <param name="cil">The CIL processor.</param>
+        /// <param name="instruction">The instruction to handle.</param>
+        /// <param name="assemblyMap">Metadata for mapping assemblies to the current platform.</param>
+        /// <param name="platformChanged">Whether the mod was compiled on a different platform.</param>
+        InstructionHandleResult Handle(ModuleDefinition module, ILProcessor cil, Instruction instruction, PlatformAssemblyMap assemblyMap, bool platformChanged);
+    }
+}
diff --git a/src/SMAPI/Framework/ModLoading/IncompatibleInstructionException.cs b/src/SMAPI/Framework/ModLoading/IncompatibleInstructionException.cs
new file mode 100644
index 00000000..17ec24b1
--- /dev/null
+++ b/src/SMAPI/Framework/ModLoading/IncompatibleInstructionException.cs
@@ -0,0 +1,35 @@
+using System;
+
+namespace StardewModdingAPI.Framework.ModLoading
+{
+    /// <summary>An exception raised when an incompatible instruction is found while loading a mod assembly.</summary>
+    internal class IncompatibleInstructionException : Exception
+    {
+        /*********
+        ** Accessors
+        *********/
+        /// <summary>A brief noun phrase which describes the incompatible instruction that was found.</summary>
+        public string NounPhrase { get; }
+
+
+        /*********
+        ** Public methods
+        *********/
+        /// <summary>Construct an instance.</summary>
+        /// <param name="nounPhrase">A brief noun phrase which describes the incompatible instruction that was found.</param>
+        public IncompatibleInstructionException(string nounPhrase)
+            : base($"Found an incompatible CIL instruction ({nounPhrase}).")
+        {
+            this.NounPhrase = nounPhrase;
+        }
+
+        /// <summary>Construct an instance.</summary>
+        /// <param name="nounPhrase">A brief noun phrase which describes the incompatible instruction that was found.</param>
+        /// <param name="message">A message which describes the error.</param>
+        public IncompatibleInstructionException(string nounPhrase, string message)
+            : base(message)
+        {
+            this.NounPhrase = nounPhrase;
+        }
+    }
+}
diff --git a/src/SMAPI/Framework/ModLoading/InstructionHandleResult.cs b/src/SMAPI/Framework/ModLoading/InstructionHandleResult.cs
new file mode 100644
index 00000000..0ae598fc
--- /dev/null
+++ b/src/SMAPI/Framework/ModLoading/InstructionHandleResult.cs
@@ -0,0 +1,24 @@
+namespace StardewModdingAPI.Framework.ModLoading
+{
+    /// <summary>Indicates how an instruction was handled.</summary>
+    internal enum InstructionHandleResult
+    {
+        /// <summary>No special handling is needed.</summary>
+        None,
+
+        /// <summary>The instruction was successfully rewritten for compatibility.</summary>
+        Rewritten,
+
+        /// <summary>The instruction is not compatible and can't be rewritten for compatibility.</summary>
+        NotCompatible,
+
+        /// <summary>The instruction is compatible, but patches the game in a way that may impact stability.</summary>
+        DetectedGamePatch,
+
+        /// <summary>The instruction is compatible, but affects the save serializer in a way that may make saves unloadable without the mod.</summary>
+        DetectedSaveSerialiser,
+
+        /// <summary>The instruction is compatible, but uses the <c>dynamic</c> keyword which won't work on Linux/Mac.</summary>
+        DetectedDynamic
+    }
+}
diff --git a/src/SMAPI/Framework/ModLoading/InvalidModStateException.cs b/src/SMAPI/Framework/ModLoading/InvalidModStateException.cs
new file mode 100644
index 00000000..075e237a
--- /dev/null
+++ b/src/SMAPI/Framework/ModLoading/InvalidModStateException.cs
@@ -0,0 +1,14 @@
+using System;
+
+namespace StardewModdingAPI.Framework.ModLoading
+{
+    /// <summary>An exception which indicates that something went seriously wrong while loading mods, and SMAPI should abort outright.</summary>
+    internal class InvalidModStateException : Exception
+    {
+        /// <summary>Construct an instance.</summary>
+        /// <param name="message">The error message.</param>
+        /// <param name="ex">The underlying exception, if any.</param>
+        public InvalidModStateException(string message, Exception ex = null)
+            : base(message, ex) { }
+    }
+}
diff --git a/src/SMAPI/Framework/ModLoading/ModDependencyStatus.cs b/src/SMAPI/Framework/ModLoading/ModDependencyStatus.cs
new file mode 100644
index 00000000..0774b487
--- /dev/null
+++ b/src/SMAPI/Framework/ModLoading/ModDependencyStatus.cs
@@ -0,0 +1,18 @@
+namespace StardewModdingAPI.Framework.ModLoading
+{
+    /// <summary>The status of a given mod in the dependency-sorting algorithm.</summary>
+    internal enum ModDependencyStatus
+    {
+        /// <summary>The mod hasn't been visited yet.</summary>
+        Queued,
+
+        /// <summary>The mod is currently being analysed as part of a dependency chain.</summary>
+        Checking,
+
+        /// <summary>The mod has already been sorted.</summary>
+        Sorted,
+
+        /// <summary>The mod couldn't be sorted due to a metadata issue (e.g. missing dependencies).</summary>
+        Failed
+    }
+}
diff --git a/src/SMAPI/Framework/ModLoading/ModMetadata.cs b/src/SMAPI/Framework/ModLoading/ModMetadata.cs
new file mode 100644
index 00000000..5055da75
--- /dev/null
+++ b/src/SMAPI/Framework/ModLoading/ModMetadata.cs
@@ -0,0 +1,68 @@
+using StardewModdingAPI.Framework.Models;
+
+namespace StardewModdingAPI.Framework.ModLoading
+{
+    /// <summary>Metadata for a mod.</summary>
+    internal class ModMetadata : IModMetadata
+    {
+        /*********
+        ** Accessors
+        *********/
+        /// <summary>The mod's display name.</summary>
+        public string DisplayName { get; }
+
+        /// <summary>The mod's full directory path.</summary>
+        public string DirectoryPath { get; }
+
+        /// <summary>The mod manifest.</summary>
+        public IManifest Manifest { get; }
+
+        /// <summary>Metadata about the mod from SMAPI's internal data (if any).</summary>
+        public ModDataRecord DataRecord { get; }
+
+        /// <summary>The metadata resolution status.</summary>
+        public ModMetadataStatus Status { get; private set; }
+
+        /// <summary>The reason the metadata is invalid, if any.</summary>
+        public string Error { get; private set; }
+
+        /// <summary>The mod instance (if it was loaded).</summary>
+        public IMod Mod { get; private set; }
+
+
+        /*********
+        ** Public methods
+        *********/
+        /// <summary>Construct an instance.</summary>
+        /// <param name="displayName">The mod's display name.</param>
+        /// <param name="directoryPath">The mod's full directory path.</param>
+        /// <param name="manifest">The mod manifest.</param>
+        /// <param name="dataRecord">Metadata about the mod from SMAPI's internal data (if any).</param>
+        public ModMetadata(string displayName, string directoryPath, IManifest manifest, ModDataRecord dataRecord)
+        {
+            this.DisplayName = displayName;
+            this.DirectoryPath = directoryPath;
+            this.Manifest = manifest;
+            this.DataRecord = dataRecord;
+        }
+
+        /// <summary>Set the mod status.</summary>
+        /// <param name="status">The metadata resolution status.</param>
+        /// <param name="error">The reason the metadata is invalid, if any.</param>
+        /// <returns>Return the instance for chaining.</returns>
+        public IModMetadata SetStatus(ModMetadataStatus status, string error = null)
+        {
+            this.Status = status;
+            this.Error = error;
+            return this;
+        }
+
+        /// <summary>Set the mod instance.</summary>
+        /// <param name="mod">The mod instance to set.</param>
+        public IModMetadata SetMod(IMod mod)
+        {
+            this.Mod = mod;
+            return this;
+        }
+    }
+}
diff --git a/src/SMAPI/Framework/ModLoading/ModMetadataStatus.cs b/src/SMAPI/Framework/ModLoading/ModMetadataStatus.cs
new file mode 100644
index 00000000..ab65f7b4
--- /dev/null
+++ b/src/SMAPI/Framework/ModLoading/ModMetadataStatus.cs
@@ -0,0 +1,12 @@
+namespace StardewModdingAPI.Framework.ModLoading
+{
+    /// <summary>Indicates the status of a mod's metadata resolution.</summary>
+    internal enum ModMetadataStatus
+    {
+        /// <summary>The mod has been found, but hasn't been processed yet.</summary>
+        Found,
+
+        /// <summary>The mod cannot be loaded.</summary>
+        Failed
+    }
+}
diff --git a/src/SMAPI/Framework/ModLoading/ModResolver.cs b/src/SMAPI/Framework/ModLoading/ModResolver.cs
new file mode 100644
index 00000000..d0ef1b08
--- /dev/null
+++ b/src/SMAPI/Framework/ModLoading/ModResolver.cs
@@ -0,0 +1,366 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using StardewModdingAPI.Framework.Exceptions;
+using StardewModdingAPI.Framework.Models;
+using StardewModdingAPI.Framework.Serialisation;
+
+namespace StardewModdingAPI.Framework.ModLoading
+{
+    /// <summary>Finds and processes mod metadata.</summary>
+    internal class ModResolver
+    {
+        /*********
+        ** Public methods
+        *********/
+        /// <summary>Get manifest metadata for each folder in the given root path.</summary>
+        /// <param name="rootPath">The root path to search for mods.</param>
+        /// <param name="jsonHelper">The JSON helper with which to read manifests.</param>
+        /// <param name="dataRecords">Metadata about mods from SMAPI's internal data.</param>
+        /// <returns>Returns the manifests by relative folder.</returns>
+        public IEnumerable<IModMetadata> ReadManifests(string rootPath, JsonHelper jsonHelper, IEnumerable<ModDataRecord> dataRecords)
+        {
+            dataRecords = dataRecords.ToArray();
+
+            foreach (DirectoryInfo modDir in this.GetModFolders(rootPath))
+            {
+                // read file
+                Manifest manifest = null;
+                string path = Path.Combine(modDir.FullName, "manifest.json");
+                string error = null;
+                try
+                {
+                    // read manifest
+                    manifest = jsonHelper.ReadJsonFile<Manifest>(path);
+
+                    // validate
+                    if (manifest == null)
+                    {
+                        error = File.Exists(path)
+                            ? "its manifest is invalid."
+                            : "it doesn't have a manifest.";
+                    }
+                    else if (string.IsNullOrWhiteSpace(manifest.EntryDll))
+                        error = "its manifest doesn't set an entry DLL.";
+                }
+                catch (SParseException ex)
+                {
+                    error = $"parsing its manifest failed: {ex.Message}";
+                }
+                catch (Exception ex)
+                {
+                    error = $"parsing its manifest failed:\n{ex.GetLogSummary()}";
+                }
+
+                // get internal data record (if any)
+                ModDataRecord dataRecord = null;
+                if (manifest != null)
+                {
+                    string key = !string.IsNullOrWhiteSpace(manifest.UniqueID) ? manifest.UniqueID : manifest.EntryDll;
+                    dataRecord = dataRecords.FirstOrDefault(record => record.ID.Matches(key, manifest));
+                }
+
+                // add default update keys
+                if (manifest != null && manifest.UpdateKeys == null && dataRecord?.UpdateKeys != null)
+                    manifest.UpdateKeys = dataRecord.UpdateKeys;
+
+                // build metadata
+                string displayName = !string.IsNullOrWhiteSpace(manifest?.Name)
+                    ? manifest.Name
+                    : modDir.FullName.Replace(rootPath, "").Trim('/', '\\');
+                ModMetadataStatus status = error == null
+                    ? ModMetadataStatus.Found
+                    : ModMetadataStatus.Failed;
+
+                yield return new ModMetadata(displayName, modDir.FullName, manifest, dataRecord).SetStatus(status, error);
+            }
+        }
+
+        /// <summary>Validate manifest metadata.</summary>
+        /// <param name="mods">The mod manifests to validate.</param>
+        /// <param name="apiVersion">The current SMAPI version.</param>
+        /// <param name="vendorModUrls">Maps vendor keys (like <c>Nexus</c>) to their mod URL template (where <c>{0}</c> is the mod ID).</param>
+        public void ValidateManifests(IEnumerable<IModMetadata> mods, ISemanticVersion apiVersion, IDictionary<string, string> vendorModUrls)
+        {
+            mods = mods.ToArray();
+
+            // validate each manifest
+            foreach (IModMetadata mod in mods)
+            {
+                // skip if already failed
+                if (mod.Status == ModMetadataStatus.Failed)
+                    continue;
+
+                // validate compatibility
+                ModCompatibility compatibility = mod.DataRecord?.GetCompatibility(mod.Manifest.Version);
+                switch (compatibility?.Status)
+                {
+                    case ModStatus.Obsolete:
+                        mod.SetStatus(ModMetadataStatus.Failed, $"it's obsolete: {compatibility.ReasonPhrase}");
+                        continue;
+
+                    case ModStatus.AssumeBroken:
+                        {
+                            // get reason
+                            string reasonPhrase = compatibility.ReasonPhrase ?? "it's no longer compatible";
+
+                            // get update URLs
+                            List<string> updateUrls = new List<string>();
+                            foreach (string key in mod.Manifest.UpdateKeys ?? new string[0])
+                            {
+                                string[] parts = key.Split(new[] { ':' }, 2);
+                                if (parts.Length != 2)
+                                    continue;
+
+                                string vendorKey = parts[0].Trim();
+                                string modID = parts[1].Trim();
+
+                                if (vendorModUrls.TryGetValue(vendorKey, out string urlTemplate))
+                                    updateUrls.Add(string.Format(urlTemplate, modID));
+                            }
+                            if (mod.DataRecord.AlternativeUrl != null)
+                                updateUrls.Add(mod.DataRecord.AlternativeUrl);
+
+                            // build error
+                            string error = $"{reasonPhrase}. Please check for a ";
+                            if (mod.Manifest.Version.Equals(compatibility.UpperVersion))
+                                error += "newer version";
+                            else
+                                error += $"version newer than {compatibility.UpperVersion}";
+                            error += " at " + string.Join(" or ", updateUrls);
+
+                            mod.SetStatus(ModMetadataStatus.Failed, error);
+                        }
+                        continue;
+                }
+
+                // validate SMAPI version
+                if (mod.Manifest.MinimumApiVersion?.IsNewerThan(apiVersion) == true)
+                {
+                    mod.SetStatus(ModMetadataStatus.Failed, $"it needs SMAPI {mod.Manifest.MinimumApiVersion} or later. Please update SMAPI to the latest version to use this mod.");
+                    continue;
+                }
+
+                // validate DLL path
+                string assemblyPath = Path.Combine(mod.DirectoryPath, mod.Manifest.EntryDll);
+                if (!File.Exists(assemblyPath))
+                {
+                    mod.SetStatus(ModMetadataStatus.Failed, $"its DLL '{mod.Manifest.EntryDll}' doesn't exist.");
+                    continue;
+                }
+
+                // validate required fields
+                {
+                    List<string> missingFields = new List<string>(3);
+
+                    if (string.IsNullOrWhiteSpace(mod.Manifest.Name))
+                        missingFields.Add(nameof(IManifest.Name));
+                    if (mod.Manifest.Version == null || mod.Manifest.Version.ToString() == "0.0")
+                        missingFields.Add(nameof(IManifest.Version));
+                    if (string.IsNullOrWhiteSpace(mod.Manifest.UniqueID))
+                        missingFields.Add(nameof(IManifest.UniqueID));
+
+                    if (missingFields.Any())
+                        mod.SetStatus(ModMetadataStatus.Failed, $"its manifest is missing required fields ({string.Join(", ", missingFields)}).");
+                }
+            }
+
+            // validate IDs are unique
+            {
+                var duplicatesByID = mods
+                    .GroupBy(mod => mod.Manifest?.UniqueID?.Trim(), mod => mod, StringComparer.InvariantCultureIgnoreCase)
+                    .Where(p => p.Count() > 1);
+                foreach (var group in duplicatesByID)
+                {
+                    foreach (IModMetadata mod in group)
+                    {
+                        if (mod.Status == ModMetadataStatus.Failed)
+                            continue; // don't replace metadata error
+                        mod.SetStatus(ModMetadataStatus.Failed, $"its unique ID '{mod.Manifest.UniqueID}' is used by multiple mods ({string.Join(", ", group.Select(p => p.DisplayName))}).");
+                    }
+                }
+            }
+        }
+
+        /// <summary>Sort the given mods by the order they should be loaded.</summary>
+        /// <param name="mods">The mods to process.</param>
+        public IEnumerable<IModMetadata> ProcessDependencies(IEnumerable<IModMetadata> mods)
+        {
+            // initialise metadata
+            mods = mods.ToArray();
+            var sortedMods = new Stack<IModMetadata>();
+            var states = mods.ToDictionary(mod => mod, mod => ModDependencyStatus.Queued);
+
+            // handle failed mods
+            foreach (IModMetadata mod in mods.Where(m => m.Status == ModMetadataStatus.Failed))
+            {
+                states[mod] = ModDependencyStatus.Failed;
+                sortedMods.Push(mod);
+            }
+
+            // sort mods
+            foreach (IModMetadata mod in mods)
+                this.ProcessDependencies(mods.ToArray(), mod, states, sortedMods, new List<IModMetadata>());
+
+            return sortedMods.Reverse();
+        }
+
+
+        /*********
+        ** Private methods
+        *********/
+        /// <summary>Sort a mod's dependencies by the order they should be loaded, and remove any mods that can't be loaded due to missing or conflicting dependencies.</summary>
+        /// <param name="mods">The full list of mods being validated.</param>
+        /// <param name="mod">The mod whose dependencies to process.</param>
+        /// <param name="states">The dependency state for each mod.</param>
+        /// <param name="sortedMods">The list in which to save mods sorted by dependency order.</param>
+        /// <param name="currentChain">The current change of mod dependencies.</param>
+        /// <returns>Returns the mod dependency status.</returns>
+        private ModDependencyStatus ProcessDependencies(IModMetadata[] mods, IModMetadata mod, IDictionary<IModMetadata, ModDependencyStatus> states, Stack<IModMetadata> sortedMods, ICollection<IModMetadata> currentChain)
+        {
+            // check if already visited
+            switch (states[mod])
+            {
+                // already sorted or failed
+                case ModDependencyStatus.Sorted:
+                case ModDependencyStatus.Failed:
+                    return states[mod];
+
+                // dependency loop
+                case ModDependencyStatus.Checking:
+                    // This should never happen. The higher-level mod checks if the dependency is
+                    // already being checked, so it can fail without visiting a mod twice. If this
+                    // case is hit, that logic didn't catch the dependency loop for some reason.
+                    throw new InvalidModStateException($"A dependency loop was not caught by the calling iteration ({string.Join(" => ", currentChain.Select(p => p.DisplayName))} => {mod.DisplayName})).");
+
+                // not visited yet, start processing
+                case ModDependencyStatus.Queued:
+                    break;
+
+                // sanity check
+                default:
+                    throw new InvalidModStateException($"Unknown dependency status '{states[mod]}'.");
+            }
+
+            // no dependencies, mark sorted
+            if (mod.Manifest.Dependencies == null || !mod.Manifest.Dependencies.Any())
+            {
+                sortedMods.Push(mod);
+                return states[mod] = ModDependencyStatus.Sorted;
+            }
+
+            // get dependencies
+            var dependencies =
+                (
+                    from entry in mod.Manifest.Dependencies
+                    let dependencyMod = mods.FirstOrDefault(m => string.Equals(m.Manifest?.UniqueID, entry.UniqueID, StringComparison.InvariantCultureIgnoreCase))
+                    orderby entry.UniqueID
+                    select new
+                    {
+                        ID = entry.UniqueID,
+                        MinVersion = entry.MinimumVersion,
+                        Mod = dependencyMod,
+                        IsRequired = entry.IsRequired
+                    }
+                )
+                .ToArray();
+
+            // missing required dependencies, mark failed
+            {
+                string[] failedIDs = (from entry in dependencies where entry.IsRequired && entry.Mod == null select entry.ID).ToArray();
+                if (failedIDs.Any())
+                {
+                    sortedMods.Push(mod);
+                    mod.SetStatus(ModMetadataStatus.Failed, $"it requires mods which aren't installed ({string.Join(", ", failedIDs)}).");
+                    return states[mod] = ModDependencyStatus.Failed;
+                }
+            }
+
+            // dependency min version not met, mark failed
+            {
+                string[] failedLabels =
+                    (
+                        from entry in dependencies
+                        where entry.Mod != null && entry.MinVersion != null && entry.MinVersion.IsNewerThan(entry.Mod.Manifest.Version)
+                        select $"{entry.Mod.DisplayName} (needs {entry.MinVersion} or later)"
+                    )
+                    .ToArray();
+                if (failedLabels.Any())
+                {
+                    sortedMods.Push(mod);
+                    mod.SetStatus(ModMetadataStatus.Failed, $"it needs newer versions of some mods: {string.Join(", ", failedLabels)}.");
+                    return states[mod] = ModDependencyStatus.Failed;
+                }
+            }
+
+            // process dependencies
+            {
+                states[mod] = ModDependencyStatus.Checking;
+
+                // recursively sort dependencies
+                foreach (var dependency in dependencies)
+                {
+                    IModMetadata requiredMod = dependency.Mod;
+                    var subchain = new List<IModMetadata>(currentChain) { mod };
+
+                    // ignore missing optional dependency
+                    if (!dependency.IsRequired && requiredMod == null)
+                        continue;
+
+                    // detect dependency loop
+                    if (states[requiredMod] == ModDependencyStatus.Checking)
+                    {
+                        sortedMods.Push(mod);
+                        mod.SetStatus(ModMetadataStatus.Failed, $"its dependencies have a circular reference: {string.Join(" => ", subchain.Select(p => p.DisplayName))} => {requiredMod.DisplayName}).");
+                        return states[mod] = ModDependencyStatus.Failed;
+                    }
+
+                    // recursively process each dependency
+                    var substatus = this.ProcessDependencies(mods, requiredMod, states, sortedMods, subchain);
+                    switch (substatus)
+                    {
+                        // sorted successfully
+                        case ModDependencyStatus.Sorted:
+                            break;
+
+                        // failed, which means this mod can't be loaded either
+                        case ModDependencyStatus.Failed:
+                            sortedMods.Push(mod);
+                            mod.SetStatus(ModMetadataStatus.Failed, $"it needs the '{requiredMod.DisplayName}' mod, which couldn't be loaded.");
+                            return states[mod] = ModDependencyStatus.Failed;
+
+                        // unexpected status
+                        case ModDependencyStatus.Queued:
+                        case ModDependencyStatus.Checking:
+                            throw new InvalidModStateException($"Something went wrong sorting dependencies: mod '{requiredMod.DisplayName}' unexpectedly stayed in the '{substatus}' status.");
+
+                        // sanity check
+                        default:
+                            throw new InvalidModStateException($"Unknown dependency status '{states[mod]}'.");
+                    }
+                }
+
+                // all requirements sorted successfully
+                sortedMods.Push(mod);
+                return states[mod] = ModDependencyStatus.Sorted;
+            }
+        }
+
+        /// <summary>Get all mod folders in a root folder, passing through empty folders as needed.</summary>
+        /// <param name="rootPath">The root folder path to search.</param>
+        private IEnumerable<DirectoryInfo> GetModFolders(string rootPath)
+        {
+            foreach (string modRootPath in Directory.GetDirectories(rootPath))
+            {
+                DirectoryInfo directory = new DirectoryInfo(modRootPath);
+
+                // if a folder only contains another folder, check the inner folder instead
+                while (!directory.GetFiles().Any() && directory.GetDirectories().Length == 1)
+                    directory = directory.GetDirectories().First();
+
+                yield return directory;
+            }
+        }
+    }
+}
diff --git a/src/SMAPI/Framework/ModLoading/Platform.cs b/src/SMAPI/Framework/ModLoading/Platform.cs
new file mode 100644
index 00000000..45e881c4
--- /dev/null
+++ b/src/SMAPI/Framework/ModLoading/Platform.cs
@@ -0,0 +1,12 @@
+namespace StardewModdingAPI.Framework.ModLoading
+{
+    /// <summary>The game's platform version.</summary>
+    internal enum Platform
+    {
+        /// <summary>The Linux/Mac version of the game.</summary>
+        Mono,
+
+        /// <summary>The Windows version of the game.</summary>
+        Windows
+    }
+}
diff --git a/src/SMAPI/Framework/ModLoading/PlatformAssemblyMap.cs b/src/SMAPI/Framework/ModLoading/PlatformAssemblyMap.cs
new file mode 100644
index 00000000..463f45e8
--- /dev/null
+++ b/src/SMAPI/Framework/ModLoading/PlatformAssemblyMap.cs
@@ -0,0 +1,55 @@
+using System.Collections.Generic;
+using System.Linq;
+using System.Reflection;
+using Mono.Cecil;
+
+namespace StardewModdingAPI.Framework.ModLoading
+{
+    /// <summary>Metadata for mapping assemblies to the current <see cref="Platform"/>.</summary>
+    internal class PlatformAssemblyMap
+    {
+        /*********
+        ** Accessors
+        *********/
+        /****
+        ** Data
+        ****/
+        /// <summary>The target game platform.</summary>
+        public readonly Platform TargetPlatform;
+
+        /// <summary>The short assembly names to remove as assembly reference, and replace with the <see cref="Targets"/>. These should be short names (like "Stardew Valley").</summary>
+        public readonly string[] RemoveNames;
+
+        /****
+        ** Metadata
+        ****/
+        /// <summary>The assemblies to target. Equivalent types should be rewritten to use these assemblies.</summary>
+        public readonly Assembly[] Targets;
+
+        /// <summary>An assembly => reference cache.</summary>
+        public readonly IDictionary<Assembly, AssemblyNameReference> TargetReferences;
+
+        /// <summary>An assembly => module cache.</summary>
+        public readonly IDictionary<Assembly, ModuleDefinition> TargetModules;
+
+
+        /*********
+        ** Public methods
+        *********/
+        /// <summary>Construct an instance.</summary>
+        /// <param name="targetPlatform">The target game platform.</param>
+        /// <param name="removeAssemblyNames">The assembly short names to remove (like <c>Stardew Valley</c>).</param>
+        /// <param name="targetAssemblies">The assemblies to target.</param>
+        public PlatformAssemblyMap(Platform targetPlatform, string[] removeAssemblyNames, Assembly[] targetAssemblies)
+        {
+            // save data
+            this.TargetPlatform = targetPlatform;
+            this.RemoveNames = removeAssemblyNames;
+
+            // cache assembly metadata
+            this.Targets = targetAssemblies;
+            this.TargetReferences = this.Targets.ToDictionary(assembly => assembly, assembly => AssemblyNameReference.Parse(assembly.FullName));
+            this.TargetModules = this.Targets.ToDictionary(assembly => assembly, assembly => ModuleDefinition.ReadModule(assembly.Modules.Single().FullyQualifiedName));
+        }
+    }
+}
diff --git a/src/SMAPI/Framework/ModLoading/RewriteHelper.cs b/src/SMAPI/Framework/ModLoading/RewriteHelper.cs
new file mode 100644
index 00000000..56a60a72
--- /dev/null
+++ b/src/SMAPI/Framework/ModLoading/RewriteHelper.cs
@@ -0,0 +1,94 @@
+using System;
+using System.Linq;
+using System.Reflection;
+using Mono.Cecil;
+using Mono.Cecil.Cil;
+
+namespace StardewModdingAPI.Framework.ModLoading
+{
+    /// <summary>Provides helper methods for field rewriters.</summary>
+    internal static class RewriteHelper
+    {
+        /*********
+        ** Public methods
+        *********/
+        /// <summary>Get the field reference from an instruction if it matches.</summary>
+        /// <param name="instruction">The IL instruction.</param>
+        public static FieldReference AsFieldReference(Instruction instruction)
+        {
+            return instruction.OpCode == OpCodes.Ldfld || instruction.OpCode == OpCodes.Ldsfld || instruction.OpCode == OpCodes.Stfld || instruction.OpCode == OpCodes.Stsfld
+                ? (FieldReference)instruction.Operand
+                : null;
+        }
+
+        /// <summary>Get the method reference from an instruction if it matches.</summary>
+        /// <param name="instruction">The IL instruction.</param>
+        public static MethodReference AsMethodReference(Instruction instruction)
+        {
+            return instruction.OpCode == OpCodes.Call || instruction.OpCode == OpCodes.Callvirt
+                ? (MethodReference)instruction.Operand
+                : null;
+        }
+
+        /// <summary>Get whether a type matches a type reference.</summary>
+        /// <param name="type">The defined type.</param>
+        /// <param name="reference">The type reference.</param>
+        public static bool IsSameType(Type type, TypeReference reference)
+        {
+            // same namespace & name
+            if (type.Namespace != reference.Namespace || type.Name != reference.Name)
+                return false;
+
+            // same generic parameters
+            if (type.IsGenericType)
+            {
+                if (!reference.IsGenericInstance)
+                    return false;
+
+                Type[] defGenerics = type.GetGenericArguments();
+                TypeReference[] refGenerics = ((GenericInstanceType)reference).GenericArguments.ToArray();
+                if (defGenerics.Length != refGenerics.Length)
+                    return false;
+                for (int i = 0; i < defGenerics.Length; i++)
+                {
+                    if (!RewriteHelper.IsSameType(defGenerics[i], refGenerics[i]))
+                        return false;
+                }
+            }
+
+            return true;
+        }
+
+        /// <summary>Get whether a method definition matches the signature expected by a method reference.</summary>
+        /// <param name="definition">The method definition.</param>
+        /// <param name="reference">The method reference.</param>
+        public static bool HasMatchingSignature(MethodInfo definition, MethodReference reference)
+        {
+            // same name
+            if (definition.Name != reference.Name)
+                return false;
+
+            // same arguments
+            ParameterInfo[] definitionParameters = definition.GetParameters();
+            ParameterDefinition[] referenceParameters = reference.Parameters.ToArray();
+            if (referenceParameters.Length != definitionParameters.Length)
+                return false;
+            for (int i = 0; i < referenceParameters.Length; i++)
+            {
+                if (!RewriteHelper.IsSameType(definitionParameters[i].ParameterType, referenceParameters[i].ParameterType))
+                    return false;
+            }
+            return true;
+        }
+
+        /// <summary>Get whether a type has a method whose signature matches the one expected by a method reference.</summary>
+        /// <param name="type">The type to check.</param>
+        /// <param name="reference">The method reference.</param>
+        public static bool HasMatchingSignature(Type type, MethodReference reference)
+        {
+            return type
+                .GetMethods(BindingFlags.Instance | BindingFlags.DeclaredOnly | BindingFlags.Public)
+                .Any(method => RewriteHelper.HasMatchingSignature(method, reference));
+        }
+    }
+}
diff --git a/src/SMAPI/Framework/ModLoading/Rewriters/FieldReplaceRewriter.cs b/src/SMAPI/Framework/ModLoading/Rewriters/FieldReplaceRewriter.cs
new file mode 100644
index 00000000..63358b39
--- /dev/null
+++ b/src/SMAPI/Framework/ModLoading/Rewriters/FieldReplaceRewriter.cs
@@ -0,0 +1,50 @@
+using System;
+using System.Reflection;
+using Mono.Cecil;
+using Mono.Cecil.Cil;
+using StardewModdingAPI.Framework.ModLoading.Finders;
+
+namespace StardewModdingAPI.Framework.ModLoading.Rewriters
+{
+    /// <summary>Rewrites references to one field with another.</summary>
+    internal class FieldReplaceRewriter : FieldFinder
+    {
+        /*********
+        ** Properties
+        *********/
+        /// <summary>The new field to reference.</summary>
+        private readonly FieldInfo ToField;
+
+
+        /*********
+        ** Public methods
+        *********/
+        /// <summary>Construct an instance.</summary>
+        /// <param name="type">The type whose field to which references should be rewritten.</param>
+        /// <param name="fromFieldName">The field name to rewrite.</param>
+        /// <param name="toFieldName">The new field name to reference.</param>
+        public FieldReplaceRewriter(Type type, string fromFieldName, string toFieldName)
+            : base(type.FullName, fromFieldName, InstructionHandleResult.None)
+        {
+            this.ToField = type.GetField(toFieldName);
+            if (this.ToField == null)
+                throw new InvalidOperationException($"The {type.FullName} class doesn't have a {toFieldName} field.");
+        }
+
+        /// <summary>Perform the predefined logic for an instruction if applicable.</summary>
+        /// <param name="module">The assembly module containing the instruction.</param>
+        /// <param name="cil">The CIL processor.</param>
+        /// <param name="instruction">The instruction to handle.</param>
+        /// <param name="assemblyMap">Metadata for mapping assemblies to the current platform.</param>
+        /// <param name="platformChanged">Whether the mod was compiled on a different platform.</param>
+        public override InstructionHandleResult Handle(ModuleDefinition module, ILProcessor cil, Instruction instruction, PlatformAssemblyMap assemblyMap, bool platformChanged)
+        {
+            if (!this.IsMatch(instruction))
+                return InstructionHandleResult.None;
+
+            FieldReference newRef = module.Import(this.ToField);
+            cil.Replace(instruction, cil.Create(instruction.OpCode, newRef));
+            return InstructionHandleResult.Rewritten;
+        }
+    }
+}
diff --git a/src/SMAPI/Framework/ModLoading/Rewriters/FieldToPropertyRewriter.cs b/src/SMAPI/Framework/ModLoading/Rewriters/FieldToPropertyRewriter.cs
new file mode 100644
index 00000000..a20b8bee
--- /dev/null
+++ b/src/SMAPI/Framework/ModLoading/Rewriters/FieldToPropertyRewriter.cs
@@ -0,0 +1,51 @@
+using System;
+using Mono.Cecil;
+using Mono.Cecil.Cil;
+using StardewModdingAPI.Framework.ModLoading.Finders;
+
+namespace StardewModdingAPI.Framework.ModLoading.Rewriters
+{
+    /// <summary>Rewrites field references into property references.</summary>
+    internal class FieldToPropertyRewriter : FieldFinder
+    {
+        /*********
+        ** Properties
+        *********/
+        /// <summary>The type whose field to which references should be rewritten.</summary>
+        private readonly Type Type;
+
+        /// <summary>The field name to rewrite.</summary>
+        private readonly string FieldName;
+
+
+        /*********
+        ** Public methods
+        *********/
+        /// <summary>Construct an instance.</summary>
+        /// <param name="type">The type whose field to which references should be rewritten.</param>
+        /// <param name="fieldName">The field name to rewrite.</param>
+        public FieldToPropertyRewriter(Type type, string fieldName)
+            : base(type.FullName, fieldName, InstructionHandleResult.None)
+        {
+            this.Type = type;
+            this.FieldName = fieldName;
+        }
+
+        /// <summary>Perform the predefined logic for an instruction if applicable.</summary>
+        /// <param name="module">The assembly module containing the instruction.</param>
+        /// <param name="cil">The CIL processor.</param>
+        /// <param name="instruction">The instruction to handle.</param>
+        /// <param name="assemblyMap">Metadata for mapping assemblies to the current platform.</param>
+        /// <param name="platformChanged">Whether the mod was compiled on a different platform.</param>
+        public override InstructionHandleResult Handle(ModuleDefinition module, ILProcessor cil, Instruction instruction, PlatformAssemblyMap assemblyMap, bool platformChanged)
+        {
+            if (!this.IsMatch(instruction))
+                return InstructionHandleResult.None;
+
+            string methodPrefix = instruction.OpCode == OpCodes.Ldsfld || instruction.OpCode == OpCodes.Ldfld ? "get" : "set";
+            MethodReference propertyRef = module.Import(this.Type.GetMethod($"{methodPrefix}_{this.FieldName}"));
+            cil.Replace(instruction, cil.Create(OpCodes.Call, propertyRef));
+            return InstructionHandleResult.Rewritten;
+        }
+    }
+}
diff --git a/src/SMAPI/Framework/ModLoading/Rewriters/MethodParentRewriter.cs b/src/SMAPI/Framework/ModLoading/Rewriters/MethodParentRewriter.cs
new file mode 100644
index 00000000..974fcf4c
--- /dev/null
+++ b/src/SMAPI/Framework/ModLoading/Rewriters/MethodParentRewriter.cs
@@ -0,0 +1,88 @@
+using System;
+using Mono.Cecil;
+using Mono.Cecil.Cil;
+
+namespace StardewModdingAPI.Framework.ModLoading.Rewriters
+{
+    /// <summary>Rewrites method references from one parent type to another if the signatures match.</summary>
+    internal class MethodParentRewriter : IInstructionHandler
+    {
+        /*********
+        ** Properties
+        *********/
+        /// <summary>The type whose methods to remap.</summary>
+        private readonly Type FromType;
+
+        /// <summary>The type with methods to map to.</summary>
+        private readonly Type ToType;
+
+        /// <summary>Whether to only rewrite references if loading the assembly on a different platform than it was compiled on.</summary>
+        private readonly bool OnlyIfPlatformChanged;
+
+
+        /*********
+        ** Accessors
+        *********/
+        /// <summary>A brief noun phrase indicating what the instruction finder matches.</summary>
+        public string NounPhrase { get; }
+
+
+        /*********
+        ** Public methods
+        *********/
+        /// <summary>Construct an instance.</summary>
+        /// <param name="fromType">The type whose methods to remap.</param>
+        /// <param name="toType">The type with methods to map to.</param>
+        /// <param name="onlyIfPlatformChanged">Whether to only rewrite references if loading the assembly on a different platform than it was compiled on.</param>
+        public MethodParentRewriter(Type fromType, Type toType, bool onlyIfPlatformChanged = false)
+        {
+            this.FromType = fromType;
+            this.ToType = toType;
+            this.NounPhrase = $"{fromType.Name} methods";
+            this.OnlyIfPlatformChanged = onlyIfPlatformChanged;
+        }
+
+        /// <summary>Perform the predefined logic for a method if applicable.</summary>
+        /// <param name="module">The assembly module containing the instruction.</param>
+        /// <param name="method">The method definition containing the instruction.</param>
+        /// <param name="assemblyMap">Metadata for mapping assemblies to the current platform.</param>
+        /// <param name="platformChanged">Whether the mod was compiled on a different platform.</param>
+        public InstructionHandleResult Handle(ModuleDefinition module, MethodDefinition method, PlatformAssemblyMap assemblyMap, bool platformChanged)
+        {
+            return InstructionHandleResult.None;
+        }
+
+        /// <summary>Perform the predefined logic for an instruction if applicable.</summary>
+        /// <param name="module">The assembly module containing the instruction.</param>
+        /// <param name="cil">The CIL processor.</param>
+        /// <param name="instruction">The instruction to handle.</param>
+        /// <param name="assemblyMap">Metadata for mapping assemblies to the current platform.</param>
+        /// <param name="platformChanged">Whether the mod was compiled on a different platform.</param>
+        public InstructionHandleResult Handle(ModuleDefinition module, ILProcessor cil, Instruction instruction, PlatformAssemblyMap assemblyMap, bool platformChanged)
+        {
+            if (!this.IsMatch(instruction, platformChanged))
+                return InstructionHandleResult.None;
+
+            MethodReference methodRef = (MethodReference)instruction.Operand;
+            methodRef.DeclaringType = module.Import(this.ToType);
+            return InstructionHandleResult.Rewritten;
+        }
+
+
+        /*********
+        ** Protected methods
+        *********/
+        /// <summary>Get whether a CIL instruction matches.</summary>
+        /// <param name="instruction">The IL instruction.</param>
+        /// <param name="platformChanged">Whether the mod was compiled on a different platform.</param>
+        protected bool IsMatch(Instruction instruction, bool platformChanged)
+        {
+            MethodReference methodRef = RewriteHelper.AsMethodReference(instruction);
+            return
+                methodRef != null
+                && (platformChanged || !this.OnlyIfPlatformChanged)
+                && methodRef.DeclaringType.FullName == this.FromType.FullName
+                && RewriteHelper.HasMatchingSignature(this.ToType, methodRef);
+        }
+    }
+}
diff --git a/src/SMAPI/Framework/ModLoading/Rewriters/TypeReferenceRewriter.cs b/src/SMAPI/Framework/ModLoading/Rewriters/TypeReferenceRewriter.cs
new file mode 100644
index 00000000..74f2fcdd
--- /dev/null
+++ b/src/SMAPI/Framework/ModLoading/Rewriters/TypeReferenceRewriter.cs
@@ -0,0 +1,154 @@
+using System;
+using Mono.Cecil;
+using Mono.Cecil.Cil;
+using StardewModdingAPI.Framework.ModLoading.Finders;
+
+namespace StardewModdingAPI.Framework.ModLoading.Rewriters
+{
+    /// <summary>Rewrites all references to a type.</summary>
+    internal class TypeReferenceRewriter : TypeFinder
+    {
+        /*********
+        ** Properties
+        *********/
+        /// <summary>The full type name to which to find references.</summary>
+        private readonly string FromTypeName;
+
+        /// <summary>The new type to reference.</summary>
+        private readonly Type ToType;
+
+
+        /*********
+        ** Public methods
+        *********/
+        /// <summary>Construct an instance.</summary>
+        /// <param name="fromTypeFullName">The full type name to which to find references.</param>
+        /// <param name="toType">The new type to reference.</param>
+        public TypeReferenceRewriter(string fromTypeFullName, Type toType)
+            : base(fromTypeFullName, InstructionHandleResult.None)
+        {
+            this.FromTypeName = fromTypeFullName;
+            this.ToType = toType;
+        }
+
+        /// <summary>Perform the predefined logic for a method if applicable.</summary>
+        /// <param name="module">The assembly module containing the instruction.</param>
+        /// <param name="method">The method definition containing the instruction.</param>
+        /// <param name="assemblyMap">Metadata for mapping assemblies to the current platform.</param>
+        /// <param name="platformChanged">Whether the mod was compiled on a different platform.</param>
+        public override InstructionHandleResult Handle(ModuleDefinition module, MethodDefinition method, PlatformAssemblyMap assemblyMap, bool platformChanged)
+        {
+            bool rewritten = false;
+
+            // return type
+            if (this.IsMatch(method.ReturnType))
+            {
+                method.ReturnType = this.RewriteIfNeeded(module, method.ReturnType);
+                rewritten = true;
+            }
+
+            // parameters
+            foreach (ParameterDefinition parameter in method.Parameters)
+            {
+                if (this.IsMatch(parameter.ParameterType))
+                {
+                    parameter.ParameterType = this.RewriteIfNeeded(module, parameter.ParameterType);
+                    rewritten = true;
+                }
+            }
+
+            // generic parameters
+            for (int i = 0; i < method.GenericParameters.Count; i++)
+            {
+                var parameter = method.GenericParameters[i];
+                if (this.IsMatch(parameter))
+                {
+                    TypeReference newType = this.RewriteIfNeeded(module, parameter);
+                    if (newType != parameter)
+                        method.GenericParameters[i] = new GenericParameter(parameter.Name, newType);
+                    rewritten = true;
+                }
+            }
+
+            // local variables
+            foreach (VariableDefinition variable in method.Body.Variables)
+            {
+                if (this.IsMatch(variable.VariableType))
+                {
+                    variable.VariableType = this.RewriteIfNeeded(module, variable.VariableType);
+                    rewritten = true;
+                }
+            }
+
+            return rewritten
+                ? InstructionHandleResult.Rewritten
+                : InstructionHandleResult.None;
+        }
+
+        /// <summary>Perform the predefined logic for an instruction if applicable.</summary>
+        /// <param name="module">The assembly module containing the instruction.</param>
+        /// <param name="cil">The CIL processor.</param>
+        /// <param name="instruction">The instruction to handle.</param>
+        /// <param name="assemblyMap">Metadata for mapping assemblies to the current platform.</param>
+        /// <param name="platformChanged">Whether the mod was compiled on a different platform.</param>
+        public override InstructionHandleResult Handle(ModuleDefinition module, ILProcessor cil, Instruction instruction, PlatformAssemblyMap assemblyMap, bool platformChanged)
+        {
+            if (!this.IsMatch(instruction) && !instruction.ToString().Contains(this.FromTypeName))
+                return InstructionHandleResult.None;
+
+            // field reference
+            FieldReference fieldRef = RewriteHelper.AsFieldReference(instruction);
+            if (fieldRef != null)
+            {
+                fieldRef.DeclaringType = this.RewriteIfNeeded(module, fieldRef.DeclaringType);
+                fieldRef.FieldType = this.RewriteIfNeeded(module, fieldRef.FieldType);
+            }
+
+            // method reference
+            MethodReference methodRef = RewriteHelper.AsMethodReference(instruction);
+            if (methodRef != null)
+            {
+                methodRef.DeclaringType = this.RewriteIfNeeded(module, methodRef.DeclaringType);
+                methodRef.ReturnType = this.RewriteIfNeeded(module, methodRef.ReturnType);
+                foreach (var parameter in methodRef.Parameters)
+                    parameter.ParameterType = this.RewriteIfNeeded(module, parameter.ParameterType);
+            }
+
+            // type reference
+            if (instruction.Operand is TypeReference typeRef)
+            {
+                TypeReference newRef = this.RewriteIfNeeded(module, typeRef);
+                if (typeRef != newRef)
+                    cil.Replace(instruction, cil.Create(instruction.OpCode, newRef));
+            }
+
+            return InstructionHandleResult.Rewritten;
+        }
+
+        /*********
+        ** Private methods
+        *********/
+        /// <summary>Get the adjusted type reference if it matches, else the same value.</summary>
+        /// <param name="module">The assembly module containing the instruction.</param>
+        /// <param name="type">The type to replace if it matches.</param>
+        private TypeReference RewriteIfNeeded(ModuleDefinition module, TypeReference type)
+        {
+            // root type
+            if (type.FullName == this.FromTypeName)
+                return module.Import(this.ToType);
+
+            // generic arguments
+            if (type is GenericInstanceType genericType)
+            {
+                for (int i = 0; i < genericType.GenericArguments.Count; i++)
+                    genericType.GenericArguments[i] = this.RewriteIfNeeded(module, genericType.GenericArguments[i]);
+            }
+
+            // generic parameters (e.g. constraints)
+            for (int i = 0; i < type.GenericParameters.Count; i++)
+                type.GenericParameters[i] = new GenericParameter(this.RewriteIfNeeded(module, type.GenericParameters[i]));
+
+            return type;
+        }
+    }
+}
diff --git a/src/SMAPI/Framework/ModLoading/Rewriters/VirtualEntryCallRemover.cs b/src/SMAPI/Framework/ModLoading/Rewriters/VirtualEntryCallRemover.cs
new file mode 100644
index 00000000..322a7df1
--- /dev/null
+++ b/src/SMAPI/Framework/ModLoading/Rewriters/VirtualEntryCallRemover.cs
@@ -0,0 +1,90 @@
+using System;
+using Mono.Cecil;
+using Mono.Cecil.Cil;
+
+namespace StardewModdingAPI.Framework.ModLoading.Rewriters
+{
+    /// <summary>Rewrites virtual calls to the <see cref="Mod.Entry"/> method.</summary>
+    internal class VirtualEntryCallRemover : IInstructionHandler
+    {
+        /*********
+        ** Properties
+        *********/
+        /// <summary>The type containing the method.</summary>
+        private readonly Type ToType;
+
+        /// <summary>The name of the method.</summary>
+        private readonly string MethodName;
+
+
+        /*********
+        ** Accessors
+        *********/
+        /// <summary>A brief noun phrase indicating what the instruction finder matches.</summary>
+        public string NounPhrase { get; }
+
+
+        /*********
+        ** Public methods
+        *********/
+        /// <summary>Construct an instance.</summary>
+        public VirtualEntryCallRemover()
+        {
+            this.ToType = typeof(Mod);
+            this.MethodName = nameof(Mod.Entry);
+            this.NounPhrase = $"{this.ToType.Name}::{this.MethodName}";
+        }
+
+        /// <summary>Perform the predefined logic for a method if applicable.</summary>
+        /// <param name="module">The assembly module containing the instruction.</param>
+        /// <param name="method">The method definition containing the instruction.</param>
+        /// <param name="assemblyMap">Metadata for mapping assemblies to the current platform.</param>
+        /// <param name="platformChanged">Whether the mod was compiled on a different platform.</param>
+        public InstructionHandleResult Handle(ModuleDefinition module, MethodDefinition method, PlatformAssemblyMap assemblyMap, bool platformChanged)
+        {
+            return InstructionHandleResult.None;
+        }
+
+        /// <summary>Perform the predefined logic for an instruction if applicable.</summary>
+        /// <param name="module">The assembly module containing the instruction.</param>
+        /// <param name="cil">The CIL processor.</param>
+        /// <param name="instruction">The instruction to handle.</param>
+        /// <param name="assemblyMap">Metadata for mapping assemblies to the current platform.</param>
+        /// <param name="platformChanged">Whether the mod was compiled on a different platform.</param>
+        public InstructionHandleResult Handle(ModuleDefinition module, ILProcessor cil, Instruction instruction, PlatformAssemblyMap assemblyMap, bool platformChanged)
+        {
+            if (!this.IsMatch(instruction))
+                return InstructionHandleResult.None;
+
+            // get instructions comprising method call
+            int index = cil.Body.Instructions.IndexOf(instruction);
+            Instruction loadArg0 = cil.Body.Instructions[index - 2];
+            Instruction loadArg1 = cil.Body.Instructions[index - 1];
+            if (loadArg0.OpCode != OpCodes.Ldarg_0)
+                throw new InvalidOperationException($"Unexpected instruction sequence while removing virtual {this.ToType.Name}.{this.MethodName} call: found {loadArg0.OpCode.Name} instead of {OpCodes.Ldarg_0.Name}");
+            if (loadArg1.OpCode != OpCodes.Ldarg_1)
+                throw new InvalidOperationException($"Unexpected instruction sequence while removing virtual {this.ToType.Name}.{this.MethodName} call: found {loadArg1.OpCode.Name} instead of {OpCodes.Ldarg_1.Name}");
+
+            // remove method call
+            cil.Remove(loadArg0);
+            cil.Remove(loadArg1);
+            cil.Remove(instruction);
+            return InstructionHandleResult.Rewritten;
+        }
+
+
+        /*********
+        ** Protected methods
+        *********/
+        /// <summary>Get whether a CIL instruction matches.</summary>
+        /// <param name="instruction">The IL instruction.</param>
+        protected bool IsMatch(Instruction instruction)
+        {
+            MethodReference methodRef = RewriteHelper.AsMethodReference(instruction);
+            return
+                methodRef != null
+                && methodRef.DeclaringType.FullName == this.ToType.FullName
+                && methodRef.Name == this.MethodName;
+        }
+    }
+}