test_session_cleanup.cpp exercises kill_via_cgroup() directly against two
plain forked processes (one setsid()-ing away from the other before it
exits), confirming a reparented straggler is actually reaped -- reproducing
the real escape shape (no pid namespace support at all) through a full
mount/bwrap session isn't possible from the CLI on a single run, since
--unshare-pid is a config-file-only setting, not a flag.
Also resolves TODO.md's SIGINT/SIGTERM entry and extends the relevant
CLAUDE.md sections (bwrap.{h,cpp}, session_cgroup.{h,cpp}, kill_session.{h,cpp})
with the fix's rationale and its known residual limitation (a kernel with
neither cgroup v2 nor pid namespace support still can't be reached
automatically).
ceamac
1f52bc5f6f