Every harness command that acts on one job (jobinfo per -j, jobrun,
jobkill, jobckpt, taskrun, setpend, jstart, jfinish, jfail) and
expect-job parse their job argument with cmdutil_job_arg on top of the
libxce selection parser: element ranges (reversed too) are refused with
the single-element message, invalid identities are rejected with the
parser's reason, and no command sends job 0 for a rejected argument.
Not-found results (controller -ENOENT, or jobinfo's empty reply) name
the job and, for bare identities, hint at <array-id>[k]. expect-job
matches job numbers instead of formatted text.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>