[xsl] creating a collection from an archive

["Graydon graydon@xxxxxxxxx" <xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx>]

So I have a Word document, localtest.docx, which is in the 2016 strict
version of the OOXML standard.  As such, it's a zip archive of a bunch
of XML files.  I want to apply XSLT to the XML files.

I could use the arch module and the collection function to write the whole
thing to disk and then load it from disk as a collection before doing whatever
to it and writing it to disk as an archive again, but this seems inefficient.
It would be better to read the archive into an in-memory collection, manipulate
it, and then write that back out as an archive.

I'm using XSLT 3.0 via Saxon 9.8.0.8 in oXygen.

<xsl:variable name="wordArchive" as="document-node()+">
   <xsl:variable name="arch" select="file:read-binary($wordArchiveURI)"/>
   <xsl:variable name="entries" select="arch:entries($arch)"/>
   <xsl:variable name="dirs" select="$entries[ends-with(.,'/')]"/>
   <xsl:sequence select="for $x in ($entries except $dirs)
                      return arch:extract-text($arch,$x) => parse-xml()" />
</xsl:variable>

works, in that I get a sequence of document nodes and those documents have the
expected XML content.

I don't get document nodes with associated document-uri() values or any of the
rest of the archive structure.  Those URIs are in the values returned by
arch:entries but I'm not seeing how I assign a document-uri value to a document
node.  xsl:document doesn't seem to have a facility for assigning a
document-uri value and of course you can't create an attribute whose parent is
a document node even if document-uri was an attribute in the first place.

What I want is a collection where the structure matches the Word archive,
various subdirectories and all, and I can use the doc() function to access
various compontent documents.  I can't shake the feeling that I'm missing
something obvious, but this feeling is no help in discerning what the obvious
thing is!

Thanks!
Graydon