Task #156 (sessions): pre-gateway flow created a session for the whole
task tree at once, so subtasks were visible in the PM's group chat the
moment they existed. The gateway creates subtasks one-by-one via
delegate(), losing that wiring. Added
MessagingService.propagate_sessions_to_subtask and threaded it through
the choreographer's _create_subtask_from_inputs. ChoreographerDeps grew
an optional `messaging` field so existing test wirings keep working.
Task #155 (progress): smoke-9 had zero progress entries because the dev
never called progress() explicitly. Added _record_milestone_progress and
fire it server-side from two natural milestones — open_pr ("opened PR
#N", 70%) and i_am_done ("submitted for QA review", 90%). Best-effort
write (contextlib.suppress) so a progress failure cannot break the verb
path. Extracted _open_pr_success_envelope to keep cyclomatic rank ≤ B.
Renn F
2c838c2a9e