PostHog Analytics & Feature Flags Setup

Quick Guide: One-time setup for PostHog analytics and feature flags. Covers posthog-js client provider, posthog-node server client, and environment variables. PostHog handles both analytics AND feature flags with a generous free tier (1M events + 1M flag requests/month).

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CRITICAL: Before Using This Skill

All code must follow project conventions in CLAUDE.md (kebab-case, named exports, import ordering, import type, named constants)

(You MUST initialize posthog-js only in a client/browser context - it requires browser APIs like window and localStorage)

(You MUST call posthog.shutdown(), posthog.flush(), or use captureImmediate() after server-side event capture to prevent lost events)

(You MUST use defaults: '2026-01-30' for automatic SPA page tracking and latest recommended behaviors)

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