modpacks now also parse their loader

nonpacks/library/zips.py

@@ -869,6 +869,39 @@ def _modpack_totals(files):
     }
 
 
+def _loader_from_filename(filename):
+    """Best-effort loader from a mod filename ('x_FABRIC_1.0.jar' → 'fabric')."""
+    low = str(filename).lower()
+    for token in ('fabricloader', 'fabric', 'neoforge', 'forge', 'quilt', 'rift', 'liteloader'):
+        if token in low:
+            return _normalize_modloader(token)
+    return ''
+
+
+def _modpack_loaders(zf, members, limit=12):
+    """Unique modloaders inferred for a modpack.
+
+    Folder/instance archives embed their jars, so we parse the first few for
+    their metadata. Modrinth .mrpack files only carry config overrides, so we
+    fall back to the loader encoded in the mod filenames. A sample is enough
+    because a modpack almost always targets a single loader.
+    """
+    loaders = []
+    for member in members[:limit]:
+        loader = ''
+        if str(member).lower().endswith('.jar'):
+            try:
+                meta = read_mod_manifest(zf.read(member))
+            except Exception:
+                meta = None
+            loader = (meta or {}).get('modloader') or ''
+        if not loader:
+            loader = _loader_from_filename(member)
+        if loader and loader not in loaders:
+            loaders.append(loader)
+    return loaders
+
+
 def parse_mods_manifest(path, filename=''):
     """Inspect a modpack archive and build a manifest for the Mods tab.
 
@@ -899,7 +932,8 @@ def parse_mods_manifest(path, filename=''):
                     'file_name': path_name,
                     'env': _mod_env(entry.get('env')),
                 })
-            return _modpack_result('modrinth', '', [], files)
+            modloaders = _modpack_loaders(zf, [f['file_name'] for f in files])
+            return _modpack_result('modrinth', '', modloaders, files)
 
         if 'manifest.json' in names:
             try:
@@ -951,7 +985,8 @@ def parse_mods_manifest(path, filename=''):
                 seen.add(fname)
                 mods.append({'name': fname, 'file_name': name})
         if mods:
-            return _modpack_result('instance' if is_instance else 'folder', '', [], mods)
+            modloaders = _modpack_loaders(zf, [m['file_name'] for m in mods])
+            return _modpack_result('instance' if is_instance else 'folder', '', modloaders, mods)
 
         return _modpack_result('unknown', '', [], [])
     finally: