Jekyll timezone configuration: evaluating per‑post override support

Jekyll currently applies a single timezone—set via timezone in _config.yml or the TZ environment variable—to all dates parsed from front matter and formatted by the Liquid date filter. There is no built‑in way for an individual post or page to specify a different zone, and the project has not decided whether a front‑matter timezone: key should be honored.

Introducing per‑post timezone overrides would let authors display dates in local zones without manual offset calculations, but it raises questions about backward compatibility, especially after Jekyll 4.2 began treating an unrecognized timezone value as a hard error instead of silently falling back to UTC. Any change must also consider variations in Ruby’s timezone database across versions.

Should Jekyll recognize a timezone key in a page’s front matter and apply it only to that page’s Liquid date output? What impact would this have on existing sites that rely on the global setting? How should Jekyll handle invalid or unsupported timezone values supplied in front matter?