Add 4 new tests to test_dag_progress.py:
- test_production_dag_shape: Real 15-task pipeline topology with mixed
statuses, verifying all tasks present, topological order invariant,
and correct parent relationships (e.g. finalize has 4 parents)
- test_topological_sort_invariant_complex_dag: 7-node DAG with wide
branching/merging to stress-test that all parents precede children
- test_logging_throttled_by_interval: Mocks time.monotonic to verify
ctx.log() is throttled by interval while broadcasts are not
- test_uses_broadcast_event_not_append_event_and_broadcast: Verifies
progress uses transient broadcast_event, not persisted append variant
- Add broadcast_dag_status() to dag_progress.py: fetches Hatchet run
details, transforms to DagStatusData, and broadcasts DAG_STATUS event
via WebSocket. Fire-and-forget with exception swallowing.
- Modify with_error_handling decorator to call broadcast_dag_status on
both task success and failure.
- Add DAG_STATUS to USER_ROOM_EVENTS (broadcast.py) and reconnect
filter (transcripts_websocket.py) to avoid replaying stale DAG state.
- Add initial DAG broadcast at workflow dispatch (transcript_process.py).
- Extend make_audio_progress_logger with optional transcript_id param
for transient DAG_TASK_PROGRESS events during mixdown.
- All deferred imports for fork-safety, all broadcasts fire-and-forget.
Foundation for DAG progress reporting to frontend. Ported topo sort
and task extraction from render_hatchet_run.py (Zulip worktree) to
produce structured Pydantic models instead of markdown.
