Systems

Feature flags reduce deployment risk, but over time they can quietly reshape system behavior in ways that make correctness harder to reason about.

Tests can pass with confidence while production still fails because the real gap is often hidden assumptions, not missing test cases.

Some bugs surface only under real traffic because production load changes timing, concurrency, and failure behavior even when code paths look identical.

Caching can improve performance, but it often makes system behavior harder to reason about through stale data, invalidation drift, and timing issues.