Fabric mods can be marked as Quilt-compatible

README.md

@@ -525,7 +525,23 @@ changelog-file: CHANGELOG.md
 
 #### loaders
 
-A list of supported mod loaders. If no value is provided, `fabric` will be used for valid Fabric mods, `forge` will be used for valid Forge mods, and `quilt` will be used for valid Quilt mods.
+A list of supported mod loaders. If no value is provided, `fabric` will be used for valid Fabric mods, `forge` will be used for valid Forge mods, `quilt` will be used for valid Quilt mods, and `fabric, quilt` will be used for Fabric mods that were marked as Quilt-compatible.
+
+Fabric mods can be marked as Quilt-compatible like so:
+
+- `fabric.mod.json`
+  ```json
+  {
+    // ...
+    "custom": {
+      "mc-publish": {
+        "quilt": true
+      }
+    },
+  }
+  ```
+
+<br>
 
 ```yaml
 loaders: |

src/metadata/fabric/fabric-mod-metadata.ts

@@ -39,6 +39,13 @@ function getDependenciesByKind(config: any, kind: DependencyKind): Dependency[]
     return dependencies;
 }
 
+function getLoaders(config: any): string[] {
+    if (config[action.name]?.quilt ?? config.custom?.[action.name]?.quilt) {
+        return ["fabric", "quilt"];
+    }
+    return ["fabric"];
+}
+
 export default class FabricModMetadata extends ModConfig {
     public readonly id: string;
     public readonly name: string;
@@ -51,7 +58,7 @@ export default class FabricModMetadata extends ModConfig {
         this.id = String(this.config.id ?? "");
         this.name = String(this.config.name ?? this.id);
         this.version = String(this.config.version ?? "*");
-        this.loaders = ["fabric"];
+        this.loaders = getLoaders(this.config);
         this.dependencies = DependencyKind.getValues().flatMap(x => getDependenciesByKind(this.config, x));
     }