4 files changed, 74 insertions, 11 deletions
diff --git a/src/SMAPI/Framework/ContentPack.cs b/src/SMAPI/Framework/ContentPack.cs
index 0660a367..b6add7b5 100644
--- a/src/SMAPI/Framework/ContentPack.cs
+++ b/src/SMAPI/Framework/ContentPack.cs
@@ -1,6 +1,7 @@
 using System;
 using System.Collections.Generic;
 using System.IO;
+using StardewModdingAPI.Framework.ModHelpers;
 using StardewModdingAPI.Toolkit.Serialization;
 using StardewModdingAPI.Toolkit.Utilities;
 
@@ -32,7 +33,10 @@ namespace StardewModdingAPI.Framework
         public IManifest Manifest { get; }
 
         /// <inheritdoc />
-        public ITranslationHelper Translation { get; }
+        public ITranslationHelper Translation => this.TranslationImpl;
+
+        /// <summary>The underlying translation helper.</summary>
+        internal TranslationHelper TranslationImpl { get; set; }
 
 
         /*********
@@ -44,12 +48,12 @@ namespace StardewModdingAPI.Framework
         /// <param name="content">Provides an API for loading content assets.</param>
         /// <param name="translation">Provides translations stored in the content pack's <c>i18n</c> folder.</param>
         /// <param name="jsonHelper">Encapsulates SMAPI's JSON file parsing.</param>
-        public ContentPack(string directoryPath, IManifest manifest, IContentHelper content, ITranslationHelper translation, JsonHelper jsonHelper)
+        public ContentPack(string directoryPath, IManifest manifest, IContentHelper content, TranslationHelper translation, JsonHelper jsonHelper)
         {
             this.DirectoryPath = directoryPath;
             this.Manifest = manifest;
             this.Content = content;
-            this.Translation = translation;
+            this.TranslationImpl = translation;
             this.JsonHelper = jsonHelper;
 
             foreach (string path in Directory.EnumerateFiles(this.DirectoryPath, "*", SearchOption.AllDirectories))
diff --git a/src/SMAPI/Framework/IModMetadata.cs b/src/SMAPI/Framework/IModMetadata.cs
index f5babafb..cb876ee4 100644
--- a/src/SMAPI/Framework/IModMetadata.cs
+++ b/src/SMAPI/Framework/IModMetadata.cs
@@ -1,3 +1,4 @@
+using System;
 using System.Collections.Generic;
 using StardewModdingAPI.Framework.ModHelpers;
 using StardewModdingAPI.Framework.ModLoading;
@@ -64,6 +65,9 @@ namespace StardewModdingAPI.Framework
         /// <summary>The update-check metadata for this mod (if any).</summary>
         ModEntryModel UpdateCheckData { get; }
 
+        /// <summary>The fake content packs created by this mod, if any.</summary>
+        ISet<WeakReference<ContentPack>> FakeContentPacks { get; }
+
 
         /*********
         ** Public methods
@@ -135,5 +139,8 @@ namespace StardewModdingAPI.Framework
 
         /// <summary>Get a relative path which includes the root folder name.</summary>
         string GetRelativePathWithRoot();
+
+        /// <summary>Get the currently live fake content packs created by this mod.</summary>
+        IEnumerable<ContentPack> GetFakeContentPacks();
     }
 }
diff --git a/src/SMAPI/Framework/ModLoading/ModMetadata.cs b/src/SMAPI/Framework/ModLoading/ModMetadata.cs
index 0ace084f..9e6bc61f 100644
--- a/src/SMAPI/Framework/ModLoading/ModMetadata.cs
+++ b/src/SMAPI/Framework/ModLoading/ModMetadata.cs
@@ -83,6 +83,9 @@ namespace StardewModdingAPI.Framework.ModLoading
         /// <inheritdoc />
         public bool IsContentPack => this.Manifest?.ContentPackFor != null;
 
+        /// <summary>The fake content packs created by this mod, if any.</summary>
+        public ISet<WeakReference<ContentPack>> FakeContentPacks { get; } = new HashSet<WeakReference<ContentPack>>();
+
 
         /*********
         ** Public methods
@@ -244,6 +247,21 @@ namespace StardewModdingAPI.Framework.ModLoading
             return Path.Combine(rootFolderName, this.RelativeDirectoryPath);
         }
 
+        /// <summary>Get the currently live fake content packs created by this mod.</summary>
+        public IEnumerable<ContentPack> GetFakeContentPacks()
+        {
+            foreach (var reference in this.FakeContentPacks.ToArray())
+            {
+                if (!reference.TryGetTarget(out ContentPack pack))
+                {
+                    this.FakeContentPacks.Remove(reference);
+                    continue;
+                }
+
+                yield return pack;
+            }
+        }
+
 
         /*********
         ** Private methods
diff --git a/src/SMAPI/Framework/SCore.cs b/src/SMAPI/Framework/SCore.cs
index 61fb77b2..f7efc89e 100644
--- a/src/SMAPI/Framework/SCore.cs
+++ b/src/SMAPI/Framework/SCore.cs
@@ -49,6 +49,7 @@ using StardewModdingAPI.Utilities;
 using StardewValley;
 using xTile.Display;
 using MiniMonoModHotfix = MonoMod.Utils.MiniMonoModHotfix;
+using PathUtilities = StardewModdingAPI.Toolkit.Utilities.PathUtilities;
 using SObject = StardewValley.Object;
 
 namespace StardewModdingAPI.Framework
@@ -1060,7 +1061,12 @@ namespace StardewModdingAPI.Framework
 
             // update mod translation helpers
             foreach (IModMetadata mod in this.ModRegistry.GetAll())
+            {
                 mod.Translations.SetLocale(locale, languageCode);
+
+                foreach (ContentPack contentPack in mod.GetFakeContentPacks())
+                    contentPack.TranslationImpl.SetLocale(locale, languageCode);
+            }
         }
 
         /// <summary>Raised when the low-level stage while loading a save changes.</summary>
@@ -1772,8 +1778,12 @@ namespace StardewModdingAPI.Framework
                         {
                             IMonitor packMonitor = this.LogManager.GetMonitor(packManifest.Name);
                             IContentHelper packContentHelper = new ContentHelper(contentCore, packDirPath, packManifest.UniqueID, packManifest.Name, packMonitor);
-                            ITranslationHelper packTranslationHelper = new TranslationHelper(packManifest.UniqueID, contentCore.GetLocale(), contentCore.Language);
-                            return new ContentPack(packDirPath, packManifest, packContentHelper, packTranslationHelper, this.Toolkit.JsonHelper);
+                            TranslationHelper packTranslationHelper = new TranslationHelper(packManifest.UniqueID, contentCore.GetLocale(), contentCore.Language);
+
+                            ContentPack contentPack = new ContentPack(packDirPath, packManifest, packContentHelper, packTranslationHelper, this.Toolkit.JsonHelper);
+                            this.ReloadTranslationsForTemporaryContentPack(mod, contentPack);
+                            mod.FakeContentPacks.Add(new WeakReference<ContentPack>(contentPack));
+                            return contentPack;
                         }
 
                         IModEvents events = new ModEvents(mod, this.EventManager);
@@ -1867,17 +1877,41 @@ namespace StardewModdingAPI.Framework
             // mod translations
             foreach (IModMetadata metadata in mods)
             {
-                var translations = this.ReadTranslationFiles(Path.Combine(metadata.DirectoryPath, "i18n"), out IList<string> errors);
-                if (errors.Any())
+                // top-level mod
                 {
-                    metadata.LogAsMod("Mod couldn't load some translation files:", LogLevel.Warn);
-                    foreach (string error in errors)
-                        metadata.LogAsMod($"  - {error}", LogLevel.Warn);
+                    var translations = this.ReadTranslationFiles(Path.Combine(metadata.DirectoryPath, "i18n"), out IList<string> errors);
+                    if (errors.Any())
+                    {
+                        metadata.LogAsMod("Mod couldn't load some translation files:", LogLevel.Warn);
+                        foreach (string error in errors)
+                            metadata.LogAsMod($"  - {error}", LogLevel.Warn);
+                    }
+
+                    metadata.Translations.SetTranslations(translations);
                 }
-                metadata.Translations.SetTranslations(translations);
+
+                // fake content packs
+                foreach (ContentPack pack in metadata.GetFakeContentPacks())
+                    this.ReloadTranslationsForTemporaryContentPack(metadata, pack);
             }
         }
 
+        /// <summary>Load or reload translations for a temporary content pack created by a mod.</summary>
+        /// <param name="parentMod">The parent mod which created the content pack.</param>
+        /// <param name="contentPack">The content pack instance.</param>
+        private void ReloadTranslationsForTemporaryContentPack(IModMetadata parentMod, ContentPack contentPack)
+        {
+            var translations = this.ReadTranslationFiles(Path.Combine(contentPack.DirectoryPath, "i18n"), out IList<string> errors);
+            if (errors.Any())
+            {
+                parentMod.LogAsMod($"Generated content pack at '{PathUtilities.GetRelativePath(Constants.ModsPath, contentPack.DirectoryPath)}' couldn't load some translation files:", LogLevel.Warn);
+                foreach (string error in errors)
+                    parentMod.LogAsMod($"  - {error}", LogLevel.Warn);
+            }
+
+            contentPack.TranslationImpl.SetTranslations(translations);
+        }
+
         /// <summary>Read translations from a directory containing JSON translation files.</summary>
         /// <param name="folderPath">The folder path to search.</param>
         /// <param name="errors">The errors indicating why translation files couldn't be parsed, indexed by translation filename.</param>