xorriso -extract reads the ISO9660 name tree, which on a Windows ISO has
no Rock Ridge — names come back upper-cased/truncated, so the
`efi/microsoft/boot/efisys_noprompt.bin` lookup failed ("missing from
ISO") and a repack from that tree would corrupt Windows' long file names.
Extract with 7z instead (reads the UDF/Joliet tree, preserving the real
lower-case paths), excluding 7z's synthetic `[BOOT]` dump. Verified
end-to-end on the cached 26100.32860 ISO: 7z extract → xorriso repack
yields a 5 GB ISO with autounattend.xml + post-install.ps1 at the root and
efisys_noprompt.bin as the UEFI El Torito image (no boot prompt).
Also: cap the Joliet volume id at 16 chars (silence xorriso warning), add
a 7z preflight check, and add p7zip-full to setup-host-linux.sh.
Simone
0df7305841