launcher/launcher/src/main/java/sashegdev/zernmc/launcher/minecraft/launch/LaunchCommandBuilder.java

@@ -63,18 +63,12 @@ public class LaunchCommandBuilder {
             // always use ModLauncher as main class (version.json might have
             // BootstrapLauncher which breaks with Java module system)
             if ("forge".equals(loaderType) || "neoforge".equals(loaderType)) {
-                // Ensure securejarhandler can create the "minecraft" module.
+                // Build classpath from manifest libraries only.
-                // The Forge installer only creates versions/<versionId>/<versionId>.json,
+                // The forge client jar (forge-*-client.jar) on the classpath
-                // NOT the jar. We copy the vanilla version jar there so
+                // contains the patched Minecraft classes and has
-                // securejarhandler finds it and creates the "minecraft" module.
+                // Automatic-Module-Name: minecraft in its MANIFEST.
-                ensureVersionJarForForge();
+                // We modify the ignoreList below to NOT exclude it,
-
+                // so securejarhandler creates the "minecraft" module from it.
-                // Build classpath from manifest libraries + the copied version jar.
-                // The copied jar (e.g. 1.20.1-forge-47.4.20.jar) does NOT match the
-                // "-DignoreList" pattern "forge-" (it starts with "1", not "forge-"),
-                // so securejarhandler will include it in the module layer.
-                // It also won't create automatic module "_1._20._1" because the
-                // filename is "1.20.1-forge-47.4.20.jar", not "1.20.1.jar".
                 String classpath;
                 if (manifest != null) {
                     classpath = buildClasspathFromManifest(manifest, false);
@@ -85,31 +79,38 @@ public class LaunchCommandBuilder {
                     classpath = buildVanillaClasspath();
                 }
 
-                // Add the copied version jar to classpath (if it exists).
-                // securejarhandler scans classpath JARs and creates modules.
-                // The jar name "1.20.1-forge-47.4.20.jar" is NOT in ignoreList,
-                // so it becomes a proper module with Automatic-Module-Name: minecraft.
-                Path copiedVersionJar = instance.getPath().resolve("versions")
-                    .resolve(getVersionId()).resolve(getVersionId() + ".jar");
-                if (Files.exists(copiedVersionJar) && isValidJar(copiedVersionJar)) {
-                    String sep = System.getProperty("os.name").toLowerCase().contains("win") ? ";" : ":";
-                    classpath = copiedVersionJar.toAbsolutePath().toString() + sep + classpath;
-                    System.out.println(ZAnsi.green("  Added version jar for minecraft module: " + copiedVersionJar.getFileName()));
-                }
-
                 command.add("-cp");
                 String cpFile = writeClasspathFile(classpath);
                 command.add(cpFile);
 
-                // Add JVM arguments from version.json manifest as-is.
+                // Add JVM arguments from version.json manifest.
-                // Forge's -p is a HARDCODED list of 8 bootstrap JARs (bootstraplauncher,
+                // Forge's -p is a HARDCODED list of 8 bootstrap JARs
-                // securejarhandler, asm-*, JarJarFileSystems) — NOT ${classpath}.
+                // (bootstraplauncher, securejarhandler, asm-*, JarJarFileSystems).
-                // Do NOT intercept it.
+                // Intercept -DignoreList to remove "forge-" pattern, which
+                // blocks the forge client jar (forge-*-client.jar) from being
+                // processed by securejarhandler into the "minecraft" module.
                 if (manifest != null) {
                     Map<String, String> vars = buildVariableMap(options);
                     vars.put("classpath", cpFile);
                     for (String arg : manifest.getJvmArguments()) {
-                        command.add(resolveVariable(arg, vars));
+                        String resolved = resolveVariable(arg, vars);
+                        if (resolved.startsWith("-DignoreList=")) {
+                            String value = resolved.substring("-DignoreList=".length());
+                            // Remove forge- from the comma-separated list:
+                            // - ,forge-, in the middle → just the comma
+                            // - ,forge- at the end → remove
+                            // - forge-, at the start → remove
+                            String modified = value
+                                .replace(",forge-,", ",")
+                                .replace(",forge-", "")
+                                .replace("forge-,", "");
+                            if (modified.equals("forge-")) modified = "";
+                            if (!modified.equals(value)) {
+                                System.out.println(ZAnsi.green("  Removed 'forge-' from ignoreList"));
+                            }
+                            resolved = "-DignoreList=" + modified;
+                        }
+                        command.add(resolved);
                     }
                 }