Detects the format from the root element and converts it to purpose-built JSON: OPML outlines as a tree plus a flat list of feeds, SOAP envelopes as header/body/fault with the operation name, WSDL 1.1/2.0 as services, ports, bindings, operations, messages and schema types, RSS 2.0/RSS 1.0/Atom as a normalized feed with items, and any other XML with the generic @attribute / #text mapping. The parser runs in the Worker with no entity expansion; nothing is fetched. Everything runs locally.