Port Forge run templates to the new classpath group system

src/main/java/dev/architectury/loom/forge/config/ForgeRunTemplate.java

@@ -35,6 +35,7 @@ import java.util.stream.Collectors;
 
 import com.mojang.serialization.Codec;
 import com.mojang.serialization.codecs.RecordCodecBuilder;
+import dev.architectury.loom.forge.dependency.ForgeModClassesService;
 import dev.architectury.loom.util.collection.CollectionUtil;
 import org.gradle.api.Named;
 
@@ -118,7 +119,7 @@ public record ForgeRunTemplate(
 		});
 
 		// Add MOD_CLASSES, this is something that ForgeGradle does
-		settings.getEnvironmentVariables().computeIfAbsent("MOD_CLASSES", $ -> ConfigValue.of("{source_roots}").resolve(configValueResolver));
+		settings.getEnvironmentVariables().putIfAbsent(ForgeModClassesService.ENVIRONMENT_VARIABLE, ForgeModClassesService.VARIABLE_KEY);
 	}
 
 	public Resolved resolve(ConfigValue.Resolver configValueResolver) {

src/main/java/dev/architectury/loom/forge/dependency/ForgeModClassesService.java

@@ -0,0 +1,107 @@
+package dev.architectury.loom.forge.dependency;
+
+import java.io.File;
+import java.util.stream.Collectors;
+
+import dev.architectury.loom.util.Version;
+import dev.architectury.loom.util.collection.Multimap;
+import org.gradle.api.NamedDomainObjectContainer;
+import org.gradle.api.Project;
+import org.gradle.api.artifacts.Dependency;
+import org.gradle.api.provider.MapProperty;
+import org.gradle.api.provider.Property;
+import org.gradle.api.provider.Provider;
+import org.gradle.api.tasks.Input;
+import org.gradle.api.tasks.Nested;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import net.fabricmc.loom.LoomGradleExtension;
+import net.fabricmc.loom.api.ModSettings;
+import net.fabricmc.loom.configuration.classpathgroups.ClasspathGroup;
+import net.fabricmc.loom.configuration.ide.RunConfigSettings;
+import net.fabricmc.loom.task.service.ClasspathGroupService;
+import net.fabricmc.loom.util.Constants;
+import net.fabricmc.loom.util.service.Service;
+import net.fabricmc.loom.util.service.ServiceFactory;
+import net.fabricmc.loom.util.service.ServiceType;
+
+public final class ForgeModClassesService extends Service<ForgeModClassesService.Options> {
+	public static final ServiceType<ForgeModClassesService.Options, ForgeModClassesService> TYPE = new ServiceType<>(ForgeModClassesService.Options.class, ForgeModClassesService.class);
+	private static final Logger LOGGER = LoggerFactory.getLogger(ForgeModClassesService.class);
+
+	public static final String ENVIRONMENT_VARIABLE = "MOD_CLASSES";
+	public static final String VARIABLE_KEY = "{source_roots}";
+
+	public interface Options extends Service.Options {
+		@Nested
+		MapProperty<String, ClasspathGroupService.Options> getClasspathGroupOptions();
+
+		@Input
+		Property<String> getSourceRootsSeparator();
+	}
+
+	public static Provider<Options> createOptions(Project project) {
+		return TYPE.maybeCreate(project, options -> {
+			LoomGradleExtension extension = LoomGradleExtension.get(project);
+
+			if (!extension.isForgeLike()) {
+				return false;
+			}
+
+			for (RunConfigSettings runConfigSettings : extension.getRunConfigs()) {
+				NamedDomainObjectContainer<ModSettings> modOverrides = runConfigSettings.getMods();
+				NamedDomainObjectContainer<ModSettings> modSettings = !modOverrides.isEmpty() ? modOverrides : extension.getMods();
+				options.getClasspathGroupOptions().put(runConfigSettings.getName(), ClasspathGroupService.create(project, modSettings));
+			}
+
+			options.getSourceRootsSeparator().set(getSourceRootsSeparator(project));
+			return true;
+		});
+	}
+
+	private static String getSourceRootsSeparator(Project project) {
+		LoomGradleExtension extension = LoomGradleExtension.get(project);
+
+		// Some versions of Forge 49+ requires a different separator
+		if (!extension.isForge() || extension.getForgeProvider().getVersion().getMajorVersion() < Constants.Forge.MIN_BOOTSTRAP_DEV_VERSION) {
+			return File.pathSeparator;
+		}
+
+		for (Dependency dependency : project.getConfigurations().getByName(Constants.Configurations.FORGE_DEPENDENCIES).getDependencies()) {
+			if (dependency.getGroup().equals("net.minecraftforge") && dependency.getName().equals("bootstrap-dev")) {
+				Version version = Version.parse(dependency.getVersion());
+				return version.compareTo(Version.parse("2.1.4")) >= 0 ? File.pathSeparator : ";";
+			}
+		}
+
+		LOGGER.warn("Failed to find bootstrap-dev in forge dependencies, using File.pathSeparator as separator");
+		return File.pathSeparator;
+	}
+
+	public ForgeModClassesService(Options options, ServiceFactory serviceFactory) {
+		super(options, serviceFactory);
+	}
+
+	public String getModClasses(String runConfig) {
+		// Use a set-valued multimap for deduplicating paths.
+		Multimap<String, String> modClasses = Multimap.setMultimap();
+		String separator = getOptions().getSourceRootsSeparator().get();
+		ClasspathGroupService classpathGroupService = getServiceFactory().get(getOptions().getClasspathGroupOptions().getting(runConfig));
+
+		for (ClasspathGroup group : classpathGroupService.getClasspathGroups()) {
+			// Note: In Forge 1.16.5, resources have to come first to find mods.toml
+			if (group.resourceDir() != null) {
+				modClasses.put(group.name(), group.resourceDir());
+			}
+
+			for (File file : classpathGroupService.getClasspath(group)) {
+				modClasses.put(group.name(), file.getAbsolutePath());
+			}
+		}
+
+		return modClasses.streamEntries()
+				.map(entry -> entry.left() + "%%" + entry.right())
+				.collect(Collectors.joining(separator));
+	}
+}

src/main/java/dev/architectury/loom/forge/dependency/ForgeRunsProvider.java

@@ -40,22 +40,13 @@ import dev.architectury.loom.forge.config.ConfigValue;
 import dev.architectury.loom.forge.config.ForgeRunTemplate;
 import dev.architectury.loom.forge.config.UserdevConfig;
 import dev.architectury.loom.util.DependencyDownloader;
-import dev.architectury.loom.util.Version;
-import dev.architectury.loom.util.collection.Multimap;
-import org.gradle.api.NamedDomainObjectContainer;
 import org.gradle.api.NamedDomainObjectSet;
 import org.gradle.api.Project;
-import org.gradle.api.artifacts.Dependency;
-import org.jetbrains.annotations.Nullable;
 
 import net.fabricmc.loom.LoomGradleExtension;
-import net.fabricmc.loom.api.ModSettings;
-import net.fabricmc.loom.configuration.ide.RunConfigSettings;
 import net.fabricmc.loom.util.Constants;
-import net.fabricmc.loom.util.gradle.SourceSetHelper;
-import net.fabricmc.loom.util.gradle.SourceSetReference;
 
-public class ForgeRunsProvider {
+public class ForgeRunsProvider implements ConfigValue.Resolver {
 	private final Project project;
 	private final LoomGradleExtension extension;
 	private final JsonObject json;
@@ -78,11 +69,8 @@ public class ForgeRunsProvider {
 		return new ForgeRunsProvider(project, userdevProvider.getJson(), userdevProvider.getConfig());
 	}
 
-	public ConfigValue.Resolver getResolver(@Nullable RunConfigSettings runConfig) {
-		return variable -> resolve(runConfig, variable);
-	}
-
-	private String resolve(@Nullable RunConfigSettings runConfig, ConfigValue.Variable variable) {
+	@Override
+	public String resolve(ConfigValue.Variable variable) {
 		String key = variable.name();
 		String string = '{' + key + '}';
 
@@ -128,37 +116,11 @@ public class ForgeRunsProvider {
 		} else if (key.equals("natives")) {
 			string = extension.getFiles().getNativesDirectory(project).getAbsolutePath();
 		} else if (key.equals("source_roots")) {
-			// Use a set-valued multimap for deduplicating paths.
-			Multimap<String, String> modClasses = Multimap.setMultimap();
-			NamedDomainObjectContainer<ModSettings> mods = extension.getMods();
-			String separator = getSourceRootsSeparator();
-
-			if (runConfig != null && !runConfig.getMods().isEmpty()) {
-				mods = runConfig.getMods();
-			}
-
-			for (ModSettings mod : mods) {
-				// Note: In Forge 1.16.5, resources have to come first to find mods.toml
-				for (SourceSetReference modSourceSet : mod.getModSourceSets().get()) {
-					File resourcesDir = modSourceSet.sourceSet().getOutput().getResourcesDir();
-					modClasses.put(mod.getName(), resourcesDir.getAbsolutePath());
-				}
-
-				for (File file : SourceSetHelper.getClasspath(mod, project)) {
-					modClasses.put(mod.getName(), file.getAbsolutePath());
-				}
-			}
-
-			string = modClasses.entrySet().stream()
-					.map(entry -> entry.getKey() + "%%" + entry.getValue())
-					.collect(Collectors.joining(separator));
+			// ignored, handled later using ForgeModClassesService
 		} else if (key.equals("mcp_mappings")) {
 			string = "loom.stub";
-		} else if (json.has(key)) {
-			JsonElement element = json.get(key);
-
-			if (element.isJsonArray()) {
-				string = StreamSupport.stream(element.getAsJsonArray().spliterator(), false)
+		} else if (key.equals("modules")) {
+			string = StreamSupport.stream(json.getAsJsonArray("modules").spliterator(), false)
 					.map(JsonElement::getAsString)
 					.flatMap(str -> {
 						if (str.contains(":")) {
@@ -170,9 +132,9 @@ public class ForgeRunsProvider {
 						return Stream.of(str);
 					})
 					.collect(Collectors.joining(File.pathSeparator));
-			} else {
+		} else if (json.has(key)) {
+			JsonElement element = json.get(key);
 			string = element.toString();
-			}
 		} else {
 			project.getLogger().warn("Unrecognized template! " + string);
 		}
@@ -188,21 +150,4 @@ public class ForgeRunsProvider {
 	private Set<File> minecraftClasspath() {
 		return DependencyDownloader.resolveFiles(project, project.getConfigurations().getByName(Constants.Configurations.FORGE_RUNTIME_LIBRARY), true);
 	}
-
-	private String getSourceRootsSeparator() {
-		// Some versions of Forge 49+ requires a different separator
-		if (!extension.isForge() || extension.getForgeProvider().getVersion().getMajorVersion() < Constants.Forge.MIN_BOOTSTRAP_DEV_VERSION) {
-			return File.pathSeparator;
-		}
-
-		for (Dependency dependency : project.getConfigurations().getByName(Constants.Configurations.FORGE_DEPENDENCIES).getDependencies()) {
-			if (dependency.getGroup().equals("net.minecraftforge") && dependency.getName().equals("bootstrap-dev")) {
-				Version version = Version.parse(dependency.getVersion());
-				return version.compareTo(Version.parse("2.1.4")) >= 0 ? File.pathSeparator : ";";
-			}
-		}
-
-		project.getLogger().warn("Failed to find bootstrap-dev in forge dependencies, using File.pathSeparator as separator");
-		return File.pathSeparator;
-	}
 }

src/main/java/dev/architectury/loom/util/collection/Multimap.java

@@ -9,6 +9,9 @@ import java.util.List;
 import java.util.Map;
 import java.util.SequencedSet;
 import java.util.Set;
+import java.util.stream.Stream;
+
+import net.fabricmc.loom.util.Pair;
 
 public interface Multimap<K, V> {
 	static <K, V> Specialized<K, V, SequencedSet<V>> setMultimap() {
@@ -26,6 +29,11 @@ public interface Multimap<K, V> {
 	Map<K, ? extends Collection<V>> asMap();
 	Set<? extends Map.Entry<K, ? extends Collection<V>>> entrySet();
 
+	default Stream<Pair<K, V>> streamEntries() {
+		return entrySet().stream()
+				.flatMap(entry -> entry.getValue().stream().map(value -> new Pair<>(entry.getKey(), value)));
+	}
+
 	interface Specialized<K, V, C extends Collection<V>> extends Multimap<K, V> {
 		@Override
 		C get(K key);

src/main/java/net/fabricmc/loom/LoomCompanionGradlePlugin.java

@@ -34,6 +34,7 @@ import net.fabricmc.loom.util.Constants;
 
 public class LoomCompanionGradlePlugin implements Plugin<Project> {
 	public static final String NAME = "dev.architectury.loom-companion";
+	public static final String UPSTREAM_NAME = "net.fabricmc.fabric-loom-companion";
 
 	@Override
 	public void apply(@NotNull Project project) {

src/main/java/net/fabricmc/loom/api/ModSettings.java

@@ -36,6 +36,7 @@ import org.gradle.api.artifacts.Configuration;
 import org.gradle.api.artifacts.Dependency;
 import org.gradle.api.artifacts.ProjectDependency;
 import org.gradle.api.file.ConfigurableFileCollection;
+import org.gradle.api.file.DirectoryProperty;
 import org.gradle.api.provider.ListProperty;
 import org.gradle.api.tasks.SourceSet;
 import org.jetbrains.annotations.ApiStatus;
@@ -54,6 +55,13 @@ public abstract class ModSettings implements Named {
 	 */
 	public abstract ConfigurableFileCollection getModFiles();
 
+	/**
+	 * The main resource directory in the mod.
+	 * On Forge and NeoForge, this is the resource directory that contains mods.toml.
+	 */
+	@ApiStatus.Experimental
+	public abstract DirectoryProperty getMainResourceDirectory();
+
 	@Inject
 	public ModSettings() {
 		getExternalGroups().finalizeValueOnRead();
@@ -125,6 +133,14 @@ public abstract class ModSettings implements Named {
 			SourceSetReference ref = new SourceSetReference(SourceSetHelper.getSourceSetByName(sourceSetName, getProject()), getProject());
 			List<File> classpath = SourceSetHelper.getClasspath(ref, false);
 			getModFiles().from(classpath);
+
+			// Arch: store resource dir
+			File resourcesDir = ref.sourceSet().getOutput().getResourcesDir();
+
+			if (resourcesDir != null && !getMainResourceDirectory().isPresent()) {
+				getMainResourceDirectory().set(resourcesDir);
+			}
+
 			return;
 		}
 

src/main/java/net/fabricmc/loom/configuration/classpathgroups/ClasspathGroup.java

@@ -30,15 +30,20 @@ import java.util.ArrayList;
 import java.util.List;
 import java.util.Set;
 
+import org.gradle.api.file.FileSystemLocation;
+import org.jetbrains.annotations.Nullable;
+
 import net.fabricmc.loom.api.ModSettings;
 
-public record ClasspathGroup(List<String> paths, List<ExternalClasspathGroup> externalGroups) implements Serializable {
+public record ClasspathGroup(String name, @Nullable String resourceDir, List<String> paths, List<ExternalClasspathGroup> externalGroups) implements Serializable {
 	public static List<ClasspathGroup> fromModSettings(Set<ModSettings> modSettings) {
-		return modSettings.stream().map(s -> new ClasspathGroup(getPaths(s), s.getExternalGroups().get())).toList();
+		return modSettings.stream().map(s -> new ClasspathGroup(s.getName(), getAbsolutePath(s.getMainResourceDirectory().getOrNull()), getPaths(s), s.getExternalGroups().get())).toList();
 	}
 
 	// TODO remove this constructor when updating to Gradle 9.0, works around an issue where config cache cannot serialize immutable lists
-	public ClasspathGroup(List<String> paths, List<ExternalClasspathGroup> externalGroups) {
+	public ClasspathGroup(String name, @Nullable String resourceDir, List<String> paths, List<ExternalClasspathGroup> externalGroups) {
+		this.name = name;
+		this.resourceDir = resourceDir;
 		this.paths = new ArrayList<>(paths);
 		this.externalGroups = new ArrayList<>(externalGroups);
 	}
@@ -50,4 +55,12 @@ public record ClasspathGroup(List<String> paths, List<ExternalClasspathGroup> ex
 				.map(File::getAbsolutePath)
 				.toList();
 	}
+
+	private static @Nullable String getAbsolutePath(@Nullable FileSystemLocation location) {
+		if (location == null) {
+			return null;
+		}
+
+		return location.getAsFile().getAbsolutePath();
+	}
 }

src/main/java/net/fabricmc/loom/configuration/ide/RunConfig.java

@@ -77,6 +77,7 @@ public class RunConfig {
 	public Map<String, Object> environmentVariables;
 	public String projectName;
 	public String folderName;
+	public String name;
 
 	// Turns camelCase/PascalCase into Capital Case
 	// caseConversionExample -> Case Conversion Example
@@ -135,6 +136,7 @@ public class RunConfig {
 		boolean appendProjectPath = settings.getAppendProjectPathToConfigName().get();
 		RunConfig runConfig = new RunConfig();
 		runConfig.configName = configName;
+		runConfig.name = name;
 
 		if (appendProjectPath && !GradleUtils.isRootProject(project)) {
 			runConfig.configName += " (" + project.getPath() + ")";

src/main/java/net/fabricmc/loom/configuration/ide/RunConfigSettings.java

@@ -446,7 +446,7 @@ public abstract class RunConfigSettings implements Named {
 			ForgeRunTemplate template = runsProvider.getTemplates().findByName(templateName);
 
 			if (template != null) {
-				template.applyTo(this, runsProvider.getResolver(this));
+				template.applyTo(this, runsProvider);
 			} else {
 				project.getLogger().warn("Could not find Forge run template with name '{}'", templateName);
 			}

src/main/java/net/fabricmc/loom/configuration/ide/idea/IdeaSyncTask.java

@@ -43,12 +43,14 @@ import javax.xml.transform.TransformerFactory;
 import javax.xml.transform.dom.DOMSource;
 import javax.xml.transform.stream.StreamResult;
 
+import dev.architectury.loom.forge.dependency.ForgeModClassesService;
 import org.gradle.api.Project;
 import org.gradle.api.file.RegularFileProperty;
 import org.gradle.api.provider.ListProperty;
 import org.gradle.api.provider.Property;
 import org.gradle.api.tasks.Input;
 import org.gradle.api.tasks.Nested;
+import org.gradle.api.tasks.Optional;
 import org.gradle.api.tasks.OutputFile;
 import org.gradle.api.tasks.TaskAction;
 import org.jetbrains.annotations.VisibleForTesting;
@@ -64,6 +66,7 @@ import net.fabricmc.loom.configuration.ide.RunConfig;
 import net.fabricmc.loom.configuration.ide.RunConfigSettings;
 import net.fabricmc.loom.task.AbstractLoomTask;
 import net.fabricmc.loom.util.Constants;
+import net.fabricmc.loom.util.service.ScopedServiceFactory;
 
 public abstract class IdeaSyncTask extends AbstractLoomTask {
 	private static final Logger LOGGER = LoggerFactory.getLogger(IdeaSyncTask.class);
@@ -71,16 +74,29 @@ public abstract class IdeaSyncTask extends AbstractLoomTask {
 	@Nested
 	protected abstract ListProperty<IntelijRunConfig> getIdeaRunConfigs();
 
+	@Nested
+	@Optional
+	protected abstract Property<ForgeModClassesService.Options> getModClassesOptions();
+
 	@Inject
 	public IdeaSyncTask() {
 		setGroup(Constants.TaskGroup.IDE);
 		getIdeaRunConfigs().set(getProject().provider(this::getRunConfigs));
+		getModClassesOptions().set(ForgeModClassesService.createOptions(getProject()));
 	}
 
 	@TaskAction
 	public void runTask() throws IOException {
 		for (IntelijRunConfig config : getIdeaRunConfigs().get()) {
 			config.writeLaunchFile();
+
+			if (getModClassesOptions().isPresent()) {
+				try (var serviceFactory = new ScopedServiceFactory()) {
+					ForgeModClassesService modClassesService = serviceFactory.get(getModClassesOptions());
+					Path launchFile = config.getLaunchFile().get().getAsFile().toPath();
+					setForgeModClasses(launchFile, modClassesService.getModClasses(config.getName().get()));
+				}
+			}
 		}
 	}
 
@@ -109,6 +125,7 @@ public abstract class IdeaSyncTask extends AbstractLoomTask {
 			irc.getRunConfigXml().set(runConfigXml);
 			irc.getExcludedLibraryPaths().set(excludedLibraryPaths);
 			irc.getLaunchFile().set(runConfigFile);
+			irc.getName().set(settings.getName());
 			configs.add(irc);
 
 			settings.makeRunDir();
@@ -127,6 +144,9 @@ public abstract class IdeaSyncTask extends AbstractLoomTask {
 		@OutputFile
 		RegularFileProperty getLaunchFile();
 
+		@Input
+		Property<String> getName();
+
 		default void writeLaunchFile() throws IOException {
 			Path launchFile = getLaunchFile().get().getAsFile().toPath();
 
@@ -160,6 +180,15 @@ public abstract class IdeaSyncTask extends AbstractLoomTask {
 		}
 	}
 
+	public static void setForgeModClasses(Path runConfig, String modClasses) throws IOException {
+		final String inputXml = Files.readString(runConfig, StandardCharsets.UTF_8);
+		final String outputXml = inputXml.replace(ForgeModClassesService.VARIABLE_KEY, modClasses);
+
+		if (!inputXml.equals(outputXml)) {
+			Files.writeString(runConfig, outputXml, StandardCharsets.UTF_8);
+		}
+	}
+
 	@VisibleForTesting
 	public static String setClasspathModificationsInXml(String input, List<String> exclusions) throws Exception {
 		final DocumentBuilderFactory documentBuilderFactory = DocumentBuilderFactory.newInstance();

src/main/java/net/fabricmc/loom/task/AbstractRunTask.java

@@ -37,6 +37,7 @@ import java.util.List;
 import java.util.function.Function;
 import java.util.stream.Collectors;
 
+import dev.architectury.loom.forge.dependency.ForgeModClassesService;
 import org.gradle.api.Project;
 import org.gradle.api.file.ConfigurableFileCollection;
 import org.gradle.api.file.FileCollection;
@@ -48,6 +49,10 @@ import org.gradle.api.specs.Spec;
 import org.gradle.api.tasks.Input;
 import org.gradle.api.tasks.InputFiles;
 import org.gradle.api.tasks.JavaExec;
+import org.gradle.api.tasks.Nested;
+import org.gradle.api.tasks.Optional;
+import org.gradle.process.ProcessForkOptions;
+import org.jetbrains.annotations.ApiStatus;
 import org.jetbrains.annotations.NotNull;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -55,6 +60,7 @@ import org.slf4j.LoggerFactory;
 import net.fabricmc.loom.LoomGradleExtension;
 import net.fabricmc.loom.configuration.ide.RunConfig;
 import net.fabricmc.loom.util.Constants;
+import net.fabricmc.loom.util.service.ScopedServiceFactory;
 
 public abstract class AbstractRunTask extends JavaExec {
 	private static final CharsetEncoder ASCII_ENCODER = StandardCharsets.US_ASCII.newEncoder();
@@ -78,6 +84,15 @@ public abstract class AbstractRunTask extends JavaExec {
 	@InputFiles
 	protected abstract ConfigurableFileCollection getInternalClasspath();
 
+	@ApiStatus.Internal
+	@Nested
+	@Optional
+	protected abstract Property<ForgeModClassesService.Options> getModClassesOptions();
+
+	@ApiStatus.Internal
+	@Input
+	protected abstract Property<String> getRunConfigName();
+
 	public AbstractRunTask(Function<Project, RunConfig> configProvider) {
 		super();
 		setGroup(Constants.TaskGroup.FABRIC);
@@ -103,6 +118,9 @@ public abstract class AbstractRunTask extends JavaExec {
 		File buildCache = LoomGradleExtension.get(getProject()).getFiles().getProjectBuildCache();
 		File argFile = new File(buildCache, "argFiles/" + getName());
 		getArgFilePath().set(argFile.getAbsolutePath());
+
+		getModClassesOptions().set(ForgeModClassesService.createOptions(getProject()));
+		getRunConfigName().set(config.map(runConfig -> runConfig.name));
 	}
 
 	private boolean canUseArgFile() {
@@ -134,10 +152,23 @@ public abstract class AbstractRunTask extends JavaExec {
 
 		setWorkingDir(new File(getProjectDir().get(), getInternalRunDir().get()));
 		environment(getInternalEnvironmentVars().get());
+		configureForgeModClasses(this);
 
 		super.exec();
 	}
 
+	protected void configureForgeModClasses(ProcessForkOptions forkOptions) {
+		try (var serviceFactory = new ScopedServiceFactory()) {
+			ForgeModClassesService service = serviceFactory.getOrNull(getModClassesOptions());
+
+			if (service != null && ForgeModClassesService.VARIABLE_KEY.equals(forkOptions.getEnvironment().get(ForgeModClassesService.ENVIRONMENT_VARIABLE))) {
+				forkOptions.environment(ForgeModClassesService.ENVIRONMENT_VARIABLE, service.getModClasses(getRunConfigName().get()));
+			}
+		} catch (IOException e) {
+			throw new UncheckedIOException(e);
+		}
+	}
+
 	@Override
 	public void setWorkingDir(File dir) {
 		if (!dir.exists()) {

src/main/java/net/fabricmc/loom/task/GenEclipseRunsTask.java

@@ -35,35 +35,54 @@ import java.util.List;
 
 import javax.inject.Inject;
 
+import dev.architectury.loom.forge.dependency.ForgeModClassesService;
 import org.gradle.api.Project;
 import org.gradle.api.file.RegularFileProperty;
 import org.gradle.api.provider.ListProperty;
 import org.gradle.api.provider.Property;
 import org.gradle.api.tasks.Input;
 import org.gradle.api.tasks.Nested;
+import org.gradle.api.tasks.Optional;
 import org.gradle.api.tasks.OutputFile;
 import org.gradle.api.tasks.TaskAction;
 import org.gradle.plugins.ide.eclipse.model.EclipseModel;
+import org.jetbrains.annotations.ApiStatus;
 
 import net.fabricmc.loom.LoomGradleExtension;
 import net.fabricmc.loom.configuration.ide.RunConfig;
 import net.fabricmc.loom.configuration.ide.RunConfigSettings;
+import net.fabricmc.loom.configuration.ide.idea.IdeaSyncTask;
 import net.fabricmc.loom.util.Constants;
+import net.fabricmc.loom.util.service.ScopedServiceFactory;
 
 public abstract class GenEclipseRunsTask extends AbstractLoomTask {
 	@Nested
 	protected abstract ListProperty<EclipseRunConfig> getEclipseRunConfigs();
 
+	@ApiStatus.Internal
+	@Nested
+	@Optional
+	protected abstract Property<ForgeModClassesService.Options> getModClassesOptions();
+
 	@Inject
 	public GenEclipseRunsTask() {
 		setGroup(Constants.TaskGroup.IDE);
 		getEclipseRunConfigs().set(getProject().provider(() -> getRunConfigs(getProject())));
+		getModClassesOptions().set(ForgeModClassesService.createOptions(getProject()));
 	}
 
 	@TaskAction
 	public void genRuns() throws IOException {
 		for (EclipseRunConfig runConfig : getEclipseRunConfigs().get()) {
 			runConfig.writeLaunchFile();
+
+			if (getModClassesOptions().isPresent()) {
+				try (var serviceFactory = new ScopedServiceFactory()) {
+					ForgeModClassesService modClassesService = serviceFactory.get(getModClassesOptions());
+					Path launchFile = runConfig.getLaunchFile().get().getAsFile().toPath();
+					IdeaSyncTask.setForgeModClasses(launchFile, modClassesService.getModClasses(runConfig.getName().get()));
+				}
+			}
 		}
 	}
 
@@ -92,6 +111,7 @@ public abstract class GenEclipseRunsTask extends AbstractLoomTask {
 			EclipseRunConfig eclipseRunConfig = project.getObjects().newInstance(EclipseRunConfig.class);
 			eclipseRunConfig.getLaunchContent().set(config);
 			eclipseRunConfig.getLaunchFile().set(project.file(configs));
+			eclipseRunConfig.getName().set(name);
 			runConfigs.add(eclipseRunConfig);
 
 			settings.makeRunDir();
@@ -107,6 +127,9 @@ public abstract class GenEclipseRunsTask extends AbstractLoomTask {
 		@OutputFile
 		RegularFileProperty getLaunchFile();
 
+		@Input
+		Property<String> getName();
+
 		default void writeLaunchFile() throws IOException {
 			Path launchFile = getLaunchFile().get().getAsFile().toPath();
 

src/main/java/net/fabricmc/loom/task/GenVsCodeProjectTask.java

@@ -41,20 +41,25 @@ import javax.inject.Inject;
 import com.google.gson.JsonArray;
 import com.google.gson.JsonElement;
 import com.google.gson.JsonObject;
+import dev.architectury.loom.forge.dependency.ForgeModClassesService;
 import org.gradle.api.Project;
 import org.gradle.api.file.RegularFileProperty;
 import org.gradle.api.provider.ListProperty;
 import org.gradle.api.provider.Property;
 import org.gradle.api.services.ServiceReference;
 import org.gradle.api.tasks.Input;
+import org.gradle.api.tasks.Nested;
+import org.gradle.api.tasks.Optional;
 import org.gradle.api.tasks.OutputFile;
 import org.gradle.api.tasks.TaskAction;
+import org.jetbrains.annotations.ApiStatus;
 
 import net.fabricmc.loom.LoomGradlePlugin;
 import net.fabricmc.loom.configuration.ide.RunConfig;
 import net.fabricmc.loom.configuration.ide.RunConfigSettings;
 import net.fabricmc.loom.util.Constants;
 import net.fabricmc.loom.util.gradle.SyncTaskBuildService;
+import net.fabricmc.loom.util.service.ScopedServiceFactory;
 
 // Recommended vscode plugin pack:
 // https://marketplace.visualstudio.com/items?itemName=vscjava.vscode-java-pack
@@ -69,11 +74,17 @@ public abstract class GenVsCodeProjectTask extends AbstractLoomTask {
 	@OutputFile
 	protected abstract RegularFileProperty getLaunchJson();
 
+	@ApiStatus.Internal
+	@Nested
+	@Optional
+	protected abstract Property<ForgeModClassesService.Options> getModClassesOptions();
+
 	@Inject
 	public GenVsCodeProjectTask() {
 		setGroup(Constants.TaskGroup.IDE);
 		getLaunchConfigurations().set(getProject().provider(this::getConfigurations));
 		getLaunchJson().convention(getProject().getRootProject().getLayout().getProjectDirectory().file(".vscode/launch.json"));
+		getModClassesOptions().set(ForgeModClassesService.createOptions(getProject()));
 	}
 
 	private List<VsCodeConfiguration> getConfigurations() {
@@ -120,6 +131,18 @@ public abstract class GenVsCodeProjectTask extends AbstractLoomTask {
 		for (VsCodeConfiguration configuration : getLaunchConfigurations().get()) {
 			JsonObject configurationJson = LoomGradlePlugin.GSON.toJsonTree(configuration).getAsJsonObject();
 			configurationJson.remove("runDir");
+			configurationJson.remove("id");
+
+			if (getModClassesOptions().isPresent()) {
+				try (var serviceFactory = new ScopedServiceFactory()) {
+					ForgeModClassesService service = serviceFactory.get(getModClassesOptions());
+					JsonObject env = configurationJson.getAsJsonObject("env");
+
+					if (env != null && env.has(ForgeModClassesService.ENVIRONMENT_VARIABLE)) {
+						env.addProperty(ForgeModClassesService.ENVIRONMENT_VARIABLE, service.getModClasses(configuration.id));
+					}
+				}
+			}
 
 			final List<JsonElement> toRemove = new LinkedList<>();
 
@@ -151,6 +174,7 @@ public abstract class GenVsCodeProjectTask extends AbstractLoomTask {
 	public record VsCodeConfiguration(
 			String type,
 			String name,
+			String id,
 			String request,
 			String cwd,
 			String console,
@@ -168,6 +192,7 @@ public abstract class GenVsCodeProjectTask extends AbstractLoomTask {
 			return new VsCodeConfiguration(
 					"java",
 					runConfig.configName,
+					runConfig.name,
 					"launch",
 					"${workspaceFolder}/" + relativeRunDir,
 					"integratedTerminal",

src/main/java/net/fabricmc/loom/task/RenderDocRunTask.java

@@ -67,6 +67,7 @@ public abstract class RenderDocRunTask extends RunGameTask {
 		ExecResult result = getExecOperations().exec(exec -> {
 			exec.workingDir(new File(getProjectDir().get(), getInternalRunDir().get()));
 			exec.environment(getInternalEnvironmentVars().get());
+			configureForgeModClasses(exec);
 
 			exec.commandLine(getRenderDocExecutable().get().getAsFile());
 			exec.args(getRenderDocArgs().get());

src/main/java/net/fabricmc/loom/task/launch/GenerateDLIConfigTask.java

@@ -40,7 +40,6 @@ import java.util.Set;
 import java.util.StringJoiner;
 import java.util.stream.Collectors;
 
-import dev.architectury.loom.forge.config.ConfigValue;
 import dev.architectury.loom.forge.config.ForgeRunTemplate;
 import dev.architectury.loom.forge.dependency.ForgeRunsProvider;
 import org.gradle.api.Project;
@@ -64,10 +63,9 @@ import net.fabricmc.loom.build.IntermediaryNamespaces;
 import net.fabricmc.loom.configuration.providers.minecraft.MinecraftVersionMeta;
 import net.fabricmc.loom.configuration.providers.minecraft.mapped.MappedMinecraftProvider;
 import net.fabricmc.loom.task.AbstractLoomTask;
+import net.fabricmc.loom.task.service.ClasspathGroupService;
 import net.fabricmc.loom.util.Constants;
 import net.fabricmc.loom.util.ModPlatform;
-import net.fabricmc.loom.util.gradle.SourceSetHelper;
-import net.fabricmc.loom.task.service.ClasspathGroupService;
 import net.fabricmc.loom.util.service.ScopedServiceFactory;
 
 public abstract class GenerateDLIConfigTask extends AbstractLoomTask {
@@ -155,10 +153,9 @@ public abstract class GenerateDLIConfigTask extends AbstractLoomTask {
 		if (getExtension().isForgeLike()) {
 			getRunTemplates().addAll(getProject().provider(() -> {
 				final ForgeRunsProvider forgeRunsProvider = getExtension().getForgeRunsProvider();
-				final ConfigValue.Resolver configResolver = forgeRunsProvider.getResolver(null);
 				return forgeRunsProvider.getTemplates()
 						.stream()
-						.map(template -> template.resolve(configResolver))
+						.map(template -> template.resolve(forgeRunsProvider))
 						.toList();
 			}));
 

src/main/java/net/fabricmc/loom/task/service/ClasspathGroupService.java

@@ -69,10 +69,11 @@ public class ClasspathGroupService extends Service<ClasspathGroupService.Options
 	}
 
 	public static Provider<Options> create(Project project) {
-		return TYPE.create(project, options -> {
-			LoomGradleExtension extension = LoomGradleExtension.get(project);
-			NamedDomainObjectContainer<ModSettings> modSettings = extension.getMods();
+		return create(project, LoomGradleExtension.get(project).getMods());
+	}
 
+	public static Provider<Options> create(Project project, NamedDomainObjectContainer<ModSettings> modSettings) {
+		return TYPE.create(project, options -> {
 			if (modSettings.isEmpty()) {
 				return;
 			}
@@ -159,4 +160,8 @@ public class ClasspathGroupService extends Service<ClasspathGroupService.Options
 	public boolean hasGroups() {
 		return getOptions().getClasspathGroups().isPresent() && !getOptions().getClasspathGroups().get().isEmpty();
 	}
+
+	public List<ClasspathGroup> getClasspathGroups() {
+		return getOptions().getClasspathGroups().get();
+	}
 }

src/main/java/net/fabricmc/loom/util/gradle/GradleUtils.java

@@ -35,7 +35,6 @@ import org.gradle.api.provider.Provider;
 import net.fabricmc.loom.LoomCompanionGradlePlugin;
 import net.fabricmc.loom.LoomGradleExtension;
 import net.fabricmc.loom.LoomGradlePlugin;
-import net.fabricmc.loom.util.Constants;
 
 public final class GradleUtils {
 	private GradleUtils() {
@@ -66,7 +65,7 @@ public final class GradleUtils {
 	}
 
 	public static boolean isLoomCompanionProject(Project project) {
-		return project.getPluginManager().hasPlugin(LoomCompanionGradlePlugin.NAME);
+		return project.getPluginManager().hasPlugin(LoomCompanionGradlePlugin.NAME) || project.getPluginManager().hasPlugin(LoomCompanionGradlePlugin.UPSTREAM_NAME);
 	}
 
 	public static Provider<Boolean> getBooleanPropertyProvider(Project project, String key) {