Parses an lxmf.delivery announce app_data blob, tolerating all four legacy shapes documented in §4.3:
lxmf.delivery
app_data
[name, stamp_cost, supported_functions]
[name, stamp_cost]
[name]
A missing capability list means compression support defaults to true for backward compatibility (§4.3).
null when appData is empty/absent or the bytes are neither valid msgpack nor decodable UTF-8.
null
Parses an
lxmf.deliveryannounceapp_datablob, tolerating all four legacy shapes documented in §4.3:[name, stamp_cost, supported_functions][name, stamp_cost][name]A missing capability list means compression support defaults to true for backward compatibility (§4.3).