feat: Support deploading non-coremods without restarting the game

build.gradle.kts

@@ -5,7 +5,7 @@ plugins {
 group = "com.falsepattern"
 
 //bump this after ANY change to the deploader!
-val deploaderVersion = 2
+val deploaderVersion = 3
 
 minecraft_fp {
     java {

src/deploader/java/com/falsepattern/deploader/DependencyLoaderImpl.java

@@ -25,6 +25,7 @@ import com.falsepattern.deploader.version.RawVersion;
 import com.falsepattern.deploader.version.SemanticVersion;
 import com.falsepattern.deploader.version.Version;
 import com.google.gson.GsonBuilder;
+import com.google.gson.JsonElement;
 import com.google.gson.JsonParser;
 import io.netty.util.internal.ConcurrentSet;
 import lombok.NonNull;
@@ -41,6 +42,7 @@ import org.jetbrains.annotations.Nullable;
 
 import cpw.mods.fml.common.MetadataCollection;
 import cpw.mods.fml.common.ModMetadata;
+import cpw.mods.fml.fpdeploader.SystemExitBypassHelper;
 
 import javax.swing.JFrame;
 import javax.swing.JLabel;
@@ -81,6 +83,7 @@ import java.util.concurrent.Executors;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.atomic.AtomicLong;
 import java.util.function.Consumer;
+import java.util.jar.JarFile;
 import java.util.jar.JarInputStream;
 import java.util.regex.Pattern;
 import java.util.stream.Collectors;
@@ -123,7 +126,7 @@ public class DependencyLoaderImpl {
         metadataCollectionModListAccessor.setAccessible(true);
     }
 
-    private static AtomicBoolean modDownloaded = new AtomicBoolean(false);
+    private static AtomicBoolean needReboot = new AtomicBoolean(false);
 
     private static void ensureExists(Path directory) {
         if (!Files.exists(directory)) {
@@ -464,17 +467,17 @@ public class DependencyLoaderImpl {
             baseTasks.addAll(tasks);
             tasks = executeArtifactLoading(baseTasks, false);
         }
-        if (modDownloaded.get()) {
+        if (needReboot.get()) {
+            val msg = "One or more minecraft mods which have been loaded by the FP DepLoader require a game restart to fully install.";
             if (!SystemUtils.IS_OS_MAC) {
                 try {
-                    JOptionPane.showMessageDialog(null, "A minecraft mod has been downloaded by the FalsePatternLib dependency downloader.\nYou must restart the game to apply these changes.", "Mod Dependency Download notice", JOptionPane.WARNING_MESSAGE);
+                    JOptionPane.showMessageDialog(null, msg + "\nThe game will exit when you close this prompt.", "Mod Dependency Download notice", JOptionPane.WARNING_MESSAGE);
                 } catch (Exception ignored) {}
             }
-            val msg = "A minecraft mod has been downloaded by the FalsePatternLib dependency downloader, and requires a game restart to get installed properly.";
             for (int i = 0; i < 16; i++) {
                 LOG.warn(msg);
             }
-            System.exit(0);
+            SystemExitBypassHelper.exit();
             throw new ModDependencyDownloaded(msg);
         }
     }
@@ -1113,7 +1116,7 @@ public class DependencyLoaderImpl {
                                 Files.delete(tmpFile);
                             } else {
                                 if (isMod) {
-                                    modDownloaded.set(true);
+                                    detectModReloadRequirement(tmpFile);
                                 }
                                 try {
                                     Files.move(tmpFile, file, StandardCopyOption.ATOMIC_MOVE);
@@ -1154,6 +1157,60 @@ public class DependencyLoaderImpl {
             }
         }
 
+        private void detectModReloadRequirement(Path file) {
+            if (needReboot.get())
+                return;
+            try (val jar = new JarFile(file.toFile())) {
+                if (LowLevelCallMultiplexer.rfbDetected) {
+                    //Detect RFB plugins
+                    val entries = jar.entries();
+                    while (entries.hasMoreElements()) {
+                        val entry = entries.nextElement();
+                        if (entry.getName().contains("META-INF/rfb-plugin")) {
+                            needReboot.set(true);
+                            return;
+                        }
+                    }
+                    return;
+                }
+                //Detect coremods
+                val manifest = jar.getManifest().getMainAttributes();
+                val isCoreMod = manifest.getValue("TweakClass") != null || manifest.getValue("FMLCorePlugin") != null;
+                if (isCoreMod) {
+                    needReboot.set(true);
+                    return;
+                }
+                //Detect mixins
+                val entries = jar.entries();
+                while (entries.hasMoreElements()) {
+                    val entry = entries.nextElement();
+                    val name = entry.getName();
+                    if (name.contains("META-INF/rfb-plugin")) {
+                        needReboot.set(true);
+                        return;
+                    }
+                    if (!name.endsWith(".json")) {
+                        continue;
+                    }
+                    val data = jar.getInputStream(entry);
+                    val gson = new GsonBuilder().create();
+                    val element = gson.fromJson(new InputStreamReader(data), JsonElement.class);
+                    if (!element.isJsonObject()) {
+                        continue;
+                    }
+                    val obj = element.getAsJsonObject();
+                    if (obj.has("refmap") || obj.has("compatibilityLevel") || obj.has("target")) {
+                        //Most likely contains mixins, better safe than sorry
+                        needReboot.set(true);
+                        return;
+                    }
+                }
+            } catch (IOException e) {
+                //bail out safely
+                needReboot.set(true);
+            }
+        }
+
         private ChecksumStatus validateChecksum(String url) throws IOException {
             for (val checksumType : CHECKSUM_TYPES) {
                 val checksumURL = url + "." + checksumType;

src/deploader/java/com/falsepattern/deploader/LowLevelCallMultiplexer.java

@@ -37,7 +37,7 @@ import java.util.List;
 
 @UtilityClass
 public class LowLevelCallMultiplexer {
-    private static boolean rfbDetected = false;
+    public static boolean rfbDetected = false;
     public static void rfbDetected() {
         rfbDetected = true;
     }

src/deploader/java/cpw/mods/fml/fpdeploader/SystemExitBypassHelper.java

@@ -0,0 +1,29 @@
+/*
+ * This file is part of FalsePatternLib.
+ *
+ * Copyright (C) 2022-2025 FalsePattern
+ * All Rights Reserved
+ *
+ * The above copyright notice and this permission notice shall be included
+ * in all copies or substantial portions of the Software.
+ *
+ * FalsePatternLib is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, only version 3 of the License.
+ *
+ * FalsePatternLib is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with FalsePatternLib. If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package cpw.mods.fml.fpdeploader;
+
+public class SystemExitBypassHelper {
+    public static void exit() {
+        System.exit(0);
+    }
+}

src/deploaderStub/java/com/falsepattern/deploader/DeploaderStub.java

@@ -56,6 +56,8 @@ public final class DeploaderStub {
         if (rfb) {
             rfbDetected = true;
             RFBUtil.preinit();
+        } else {
+            LaunchWrapperUtil.preinit();
         }
         Object deploader = Launch.blackboard.get(BLACKBOARD_MARKER);
         if (deploader != null) {
@@ -203,7 +205,7 @@ public final class DeploaderStub {
             try {
                 Method exc = loader.getClass()
                                 .getDeclaredMethod("addClassLoaderExclusion", String.class);
-                exc.invoke(loader, "com_falsepattern_deploader_".replace("_", "."));
+                exc.invoke(loader, "com_falsepattern_deploader_".replace('_', '.'));
             } catch (Exception ignored) {}
         }
 
@@ -221,6 +223,9 @@ public final class DeploaderStub {
     }
 
     private static class LaunchWrapperUtil {
+        static void preinit() {
+            Launch.classLoader.addTransformerExclusion("com_falsepattern_deploader_".replace('_', '.'));
+        }
         static Path gameDir() {
             return Launch.minecraftHome == null ? Paths.get(".") : Launch.minecraftHome.toPath();
         }