A selected directory that is readable but not searchable passed the R_OK
selection check, then every entry lstat failed and the result became a
generic artifact I/O failure. The selection owner now checks search
permission for directories and reads the selection metadata inside its
classifier, so EACCES/EPERM from realpath, lstat or access is a host
access denial with the selected path and system code.
Host filesystem failures that no narrower owner classifies no longer
drop their facts: EMFILE/ENFILE become a retryable capacity constraint,
and other errno failures keep artifact I/O with the host message and
system_code, syscall and path diagnostics.
Fixes#6116Fixes#5991
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
