Guides product analytics and RUM (Real User Monitoring) event tracking in web (React/Next.js) and mobile (React Native/Expo) apps. Decides what user interactions are valuable to capture, what's noise, what's PII to avoid, and how to implement, audit, update, and remove tracking code cleanly. Covers event naming, property schemas, tracking plans, GDPR/CCPA/DPDPA compliance, OpenTelemetry semantic conventions for browser and mobile RUM, and platforms (PostHog, Segment, Mixpanel, Amplitude, Datadog RUM, Sentry, OTel, Dash0). Modes: guide (default), implement, audit, remove, plan. Triggers on "track this event", "add analytics", "what should I track", "is this PII", "tracking plan", "remove tracking", "audit analytics", "/rum-tracking".