Found both while translating the spec into code:
- `ssh -J a,b,c` alone isn't valid - ssh -J only carries jump hosts
before the final hop; it still needs a positional destination. --via's
last entry has to double as that target, which also makes --via
mandatory (there's no other field naming "the host ssh connects to"),
reversing the earlier "no" in the required column.
- A plain single-pid SIGKILL on `close --force` would leave the `ssh`
child orphaned, since a killed process can't forward anything to it.
Documents sending SIGKILL to the whole process group instead, relying
on the supervisor's own setsid() call making it the group leader.
