Race Condition Audit: find all concurrent-access bugs — FishBot aiogram

Job description

Task: Race Condition Audit — FishBot Context FishBot — Python 3.12, aiogram 3.x, SQLAlchemy 2.x async, PostgreSQL. Async bot = multiple users can trigger same handler simultaneously. Known race conditions already fixed activate subscription: SELECT FOR UPDATE + IntegrityError catch get or create user: IntegrityError on concurrent /start use promo: SELECT FOR UPDATE Where to look for NEW race conditions Files to check bot/handlers/group fishing.py — create group, join, invite bot/handlers/catch.py — monthly catch limit check bot/handlers/session.py — open/close session bot/services/payments.py — activate subscription (already fixed, verify) bot/db.py — any other check then act patterns Deliverable List of race conditions found: