Zero-Downtime Deploy

When performing a zero-downtime deployment:

1. Ensure the new version is backwards-compatible with the current database schema and API contracts.
2. Deploy the new version alongside the old version (blue/green or rolling update).
3. Run health checks on the new instances before routing traffic to them.
4. Gradually shift traffic from old to new instances.
5. Monitor error rates and latency during the traffic shift.
6. Once all traffic is on the new version and metrics are stable, tear down the old instances.
7. If issues arise during the shift, route all traffic back to the old instances immediately.