Look at parent datatypes when identifing a preferred visualization

Author: dannon

lib/galaxy/datatypes/registry.py

@@ -525,12 +525,46 @@ def get_preferred_visualization(self, datatype_extension):
         datatypes_conf.xml configuration file. These mappings determine which visualization plugin
         should be used by default when viewing datasets of a specific type.
 
+        If no direct mapping exists for the extension, this method will walk up the inheritance
+        chain to find a preferred visualization from a parent datatype class.
+
         Example configuration:
         <datatype extension="bam" type="galaxy.datatypes.binary:Bam" mimetype="application/octet-stream" display_in_upload="true">
             <visualization plugin="igv" />
         </datatype>
         """
-        return self.visualization_mappings.get(datatype_extension)
+        direct_mapping = self.visualization_mappings.get(datatype_extension)
+        if direct_mapping:
+            return direct_mapping
+
+        current_datatype = self.get_datatype_by_extension(datatype_extension)
+        if not current_datatype:
+            return None
+
+        # Use the same mapping approach as the datatypes API for consistency
+        from galaxy.managers.datatypes import view_mapping
+
+        mapping_data = view_mapping(self)
+
+        current_class_name = mapping_data.ext_to_class_name.get(datatype_extension)
+        if not current_class_name:
+            return None
+
+        current_class_mappings = mapping_data.class_to_classes.get(current_class_name, {})
+
+        # Find parent extensions that have preferred visualizations
+        for ext, visualization_mapping in self.visualization_mappings.items():
+            if ext == datatype_extension:
+                continue
+
+            parent_class_name = mapping_data.ext_to_class_name.get(ext)
+            if parent_class_name and parent_class_name in current_class_mappings:
+                self.log.debug(
+                    f"Found inherited preferred visualization '{visualization_mapping['visualization']}' for datatype '{datatype_extension}' from parent '{ext}'"
+                )
+                return visualization_mapping
+
+        return None
 
     def get_all_visualization_mappings(self):
         """