Real-World Patterns — @retry, @timer, @cache

"Three decorator patterns appear in almost every serious Python codebase: retry (for resilient API calls), timer (for performance monitoring), and cache (for expensive computations). Today you build production-quality versions of all three — the kind you'd actually use in the budget dashboard. These aren't toy implementations: they handle edge cases, have proper configuration, and integrate with Python's logging module. After this lesson you'll have a decorator library you can use in real projects."