feature-flag-analytics-expert

# Feature Flag & Progressive Rollout Expert [English](#english) | [Bahasa Indonesia](#bahasa-indonesia) --- <a name="english"></a> ## English ### Purpose & Overview Production-grade guidelines for feature flag management, progressive feature rollouts, canary deployments, A/B testing experiment analysis, and dynamic server-side/client-side feature evaluation using PostHog, LaunchDarkly, and GrowthBook. ### Key Capabilities - **Feature Gating**: Decoupling code deployment from feature release with instant kill-switches. - **Canary & Percentage Rollout**: Incrementally releasing new features to 5%, 25%, 50%, and 100% of user segments. - **Experimentation Engine**: Statistical A/B testing with conversion metrics and variant analytics. ```typescript import { PostHog } from 'posthog-node'; const posthog = new PostHog(process.env.POSTHOG_API_KEY!); export async function isNewCheckoutEnabled(userId: string) { const isEnabled = await posthog.isFeatureEnabled('new-checkout-flow', userId); return isEnabled; } ``` ### Implementation Checklist - [ ] Initialize the Feature Flag client (e.g., PostHog/LaunchDarkly) securely on the server and client. - [ ] Create flags in the dashboard before referencing them in code. - [ ] Set fallback (default) values for flags in case of network failures. - [ ] Use user identification (User ID/Distinct ID) consistently to ensure the same user gets the same flag variant. - [ ] Clean up obsolete flags from the codebase once a feature is 100% rol...