Mistakes so far:
- batch size is not applying, still at 10k
- Hanging somewhere, not seeing our verbose output.

2026-04-03 18:41:10 [INFO] routes.sync: [API] Sync job created: 052fa9c6-7758-478a-a25f-8971b230ce7f for Sybase.SAPSR3.MARA (batch_size=10,000)
2026-04-03 18:41:10 [INFO] sync.sync_jobs: [SYNC-JOB] 052fa9c6-7758-478a-a25f-8971b230ce7f: Starting SAPSR3.MARA
2026-04-03 18:41:10 [INFO] database.remote_executor: [REMOTE] Connecting via ODBC (db_type=sybase, cs=DRIVER={Sybase};SERVER=10.152.1.8;PORT=4901;DB=R3P;UID=cryst...)
2026-04-03 18:41:10 [INFO] database.remote_executor: [REMOTE] ODBC connected in 0.24s
2026-04-03 18:41:10 [INFO] notifications.change_detector: Staged: v3q_data.sapsr3_mara → v3q_data.sapsr3_mara_prev
2026-04-03 18:41:10 [INFO] database.remote_executor: [REMOTE] fetch_batched: starting streaming pipeline (batch_size=10000, queue_depth=2, query=SELECT "MANDT", "MATNR", "ERSDA", "ERNAM", "LAEDA", "AENAM", "VPSTA", "PSTAT", "...)
2026-04-03 18:41:10 [INFO] database.remote_executor: [REMOTE] Producer thread started, streaming batches to consumer...
(And it hangs forever)

Frontend side:
We are seeing the frontend probes, they are working, but the backend isn't bringing back anything useful, output:

{
    "id": "052fa9c6-7758-478a-a25f-8971b230ce7f",
    "connection_id": "3b4e1422-223f-4aee-95f9-589731ce1873",
    "connection_name": "Sybase",
    "db_type": "sybase",
    "source_schema": "SAPSR3",
    "source_table": "MARA",
    "local_table": null,
    "status": "running",
    "phase": "fetching",
    "phase_detail": "Fetching data from remote (236 columns, batch_size=10,000)...",
    "rows_fetched": 0,
    "rows_inserted": 0,
    "total_columns": 236,
    "batches_done": 0,
    "fetch_rate": null,
    "insert_rate": null,
    "error_message": null,
    "started_at": "2026-04-03T16:41:10.165998+00:00",
    "finished_at": null,
    "created_at": "2026-04-03T16:41:10.153536+00:00",
    "updated_at": "2026-04-03T16:41:10.685248+00:00"
}