Cinema presale alert bot

Problem

Tickets for premieres sell out within hours, and cinemas do not notify anyone when presales open.

Approach & architecture

• A provider interface hides each cinema's API behind normalised films and sessions, so adding a cinema chain means writing an adapter, not rewriting the bot.
• A monitor compares session sets every five minutes; the new state is saved only after at least one subscriber has actually been notified, so a failure never swallows an alert.
• A newly added cinema is adopted silently on its first cycle, so users are not flooded with existing films announced as new.

Result

Users follow a film or all presales, in Uzbek or Russian, with a one-tap unsubscribe on every alert.

What made it robust

• Alerts are batched per user to stay within Telegram limits; partial sweeps are treated as failures; health alerts fire when a source goes down.
• Runs as a non-root container.