39:- [ ] E1. pytest suite (OAuth, tokens, CSV/TXT, validation, variables, invoice gen, uniqueness, PDF, MIME, retry, rotation, clear-all, etc.)
52:  - [ ] test_campaign_engine.py (materialization, sequencing, uniqueness)
53:  - [ ] test_send_one_task.py (retry/backoff/DLQ, statuses, mocked Gmail)
54:  - [ ] test_sse_dashboard.py