Added beyond reference

This domain covers modern FullStack topics that often appear in production and senior interviews but were not explicit in a minimal JavaScript outline: **AI-assisted development**, **LLM product integration**, **privacy and data governance**, **product analytics and experimentation**, **payments and subscriptions**, and **offline-first sync**.

These areas share a pattern: probabilistic or distributed behavior, policy constraints, and user-visible failure modes. Strong answers name boundaries, evidence, auditability, and rollback—not only happy-path diagrams.

On interviews: pick two topics and connect them (e.g., LLM feature + PII governance; payments webhooks + idempotency; offline sync + analytics event ordering).

Common pitfalls: treating AI output as trusted; shipping LLM tools without authz; analytics without guardrails; payment state from browser redirects; offline UX that hides conflicts.

The trade-off is breadth of "modern stack" literacy versus depth on any one regulated or money-moving system—use child topics for depth.

Checklist:

• Name ownership and verification for AI-generated changes.
• Bound LLM capabilities and measure with evals.
• Map data flows for privacy and deletion.
• Instrument experiments before full rollout.
• Model payments as event-sourced workflows.
• Design offline UX for conflicts and retries.