The deferred launchd reload helper used start_new_session=True to detach
from the gateway's process group. However, setsid(2) alone does NOT move
the child outside the launchd job's process coalition — when launchctl
bootout fires on the gateway label, launchd terminates ALL processes in
that coalition, including the setsid-detached helper, leaving the service
permanently unloaded.
Fix by spawning the helper via launchctl submit, which creates a
transient launchd one-shot job that is wholly independent of the
gateway's coalition. This ensures the helper survives bootout and can
complete the bootstrap+verify cycle.
Also writes a durable pre-bootout marker to the reload log so the
distinction between 'helper never started' and 'helper ran but
bootout/bootstrap failed' can be diagnosed.
Fixes#69098
webtecnica
2a32fe8914