java.util gave abbreviations only for zones in the display locale's region:
an en-DE phone saw "CEST" for Berlin but "GMT-4" for New York, and an
en-US phone the reverse — ICU only surfaces the short names commonly used
where the reader is. Verified on-device (en-DE): US zones fell back to the
offset, EU ones resolved.
Ask ICU in the display language but the *zone's* region instead — New York
in en-US, Berlin in en-DE — using android.icu's zone→region map. On-device
that lights up EDT/PDT/CDT, plus BST, AEST, IST, JST that showed only the
offset before. Where a region still has no name (Athens in en-GR) the
device locale sometimes does, so fall back to it, then to the offset.
The region lookup needs android.icu, which domain/ can't import, so it's
injected: timeZoneOptions takes a regionOf lambda (default none, keeping
the module pure and JVM-tested), and the UI passes icuTimeZoneRegion.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Jean-Luc Makiola
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