Set up a staging environment for my app. I want a real, deployed environment that mirrors production so I can test deploys, migrations, and third-party integrations without gambling on real users. Build it out: 1. Same runtime and services as production: same Node/Python version, same database engine and major version, same cache and queue. Not SQLite locally then Postgres in prod. If a service is expensive, use a smaller instance, but keep the engine identical. 2. Its own environment variables and secrets, separated from production. Staging never points at production databases, production email senders, or live Stripe keys. Use sandbox/test versions of every third-party API. 3. Realistic data: an anonymized copy of production data or a substantial seed fixture. Empty databases hide the bugs that only appear at scale or with real data shapes (weird unicode, edge-case dates, users who did a thing years ago). 4. A distinct URL (staging.mydomain.com or similar) with basic-auth or IP-allowlist in front so it isn't indexed by Google and isn't accessible to random visitors. 5. Deploys happen automatically from the main branch (or a designated staging branch), so it's always current. Broken staging deploys should notify me the same way broken production ones would. 6. A written policy for what I do in staging: run migrations first, run smoke tests, verify integrations, then promote to production. Don't build a scaled-down toy version that's so different from production it hides real problems; the whole point is fidelity. The deliverable is the staging environment deployed, protected from public traffic, seeded with realistic data, wired to sandbox third parties, and a documented promote-to-prod checklist.