Feature Flag Strategy

Format: Design a feature flag strategy.

What is a Feature Flag: A toggle in the code that controls whether a new feature is visible.

Benefits:
- Deploy code without immediately enabling the feature
- Gradually roll out to a subset of users (canary release)
- Instantly disable if something goes wrong, no code rollback needed

Use cases:
- Phased rollout of major features
- A/B testing
- Emergency shutdown of problematic features