i can not even begin to figure out the source of this bug

Safari consistently fails to process XSLT when it includes an XPath with a namespace which is the first non‐default namespace declared in the root element, but only sometimes

the name or value of the namespace does not appear to matter; however, and for reasons i cannot seem to determine but presumably has to do with document structure somehow, it only manifests for certain namespaces which have only been used in the document in certain (specifics unknown) ways

the XSLT will correctly process if you simply change the order of the namespace declarations on the root element, which is not something which should ever determine whether an XML document is able to be processed or not

OH NO IT’S EVEN WORSE

it’s not whether it is the first non‐default namespace; in fact it is just that some namespaces must be declared before others (by some unknown‐to‐me standard) or else the whole fuckin’ thing breaks.