Next.js i18n: Where to Convert Dates for User Time Zones

Goal

Determine the optimal location for converting server‑side timestamps into the user’s local time zone within a Next.js application.

Current Constraints

• Server Components run on the server and cannot read navigator.timezone directly.
• The framework’s i18n routing only detects locale, not time zone.
• Time zone information must be explicitly passed from the client (e.g., via a header or query parameter).
• Server‑side conversion keeps a single source of truth but requires handling time‑zone changes during a session.
• Client‑side conversion reduces server load but demands re‑formatting whenever the user’s time zone changes.

Unresolved Questions

1. Should date conversion for a user’s time zone be performed on the server or on the client?
2. What strategy should be used to detect and react to time‑zone changes that occur while a session is active?
3. How can formatted dates be cached efficiently to balance performance and correctness?