[Elyahu41]

The issue

ZmanimFormatter.formatInstant(Instant instant, ZoneId zoneId) ignores its zoneId argument and always formats in the formatter's own zone.

The edge case

Any call where zoneId is different from the zone the ZmanimFormatter was created with. One formatter is often reused to show times for several locations, or created with UTC.

What happens

The constructor stores dateTimeFormatter.withZone(zoneId), so the formatter has an override zone. formatInstant builds instant.atZone(zoneId) and formats it, but a DateTimeFormatter with an override zone converts a ZonedDateTime to the override zone before formatting. So the requested zone is silently replaced:

ZmanimFormatter formatter = new ZmanimFormatter(ZoneId.of("UTC"));
Instant instant = Instant.parse("2020-03-25T21:37:09Z");
formatter.formatInstant(instant, ZoneId.of("America/New_York"));   // "9:37:09"  (expected 5:37:09)
formatter.formatInstant(instant, ZoneId.of("Pacific/Kiritimati")); // "9:37:09"  (expected 11:37:09)

The time shown is off by the difference between the two zones, and nothing indicates an error. With a formatter whose zone differs from the location's, every zman displayed through formatInstant is wrong.

The fix

Format with getDateTimeFormatter().withZone(zoneId), so the requested zone becomes the override zone. A formatter set through setDateTimeFormatter without a zone also works, and a null zoneId still throws as before (from instant.atZone).

Tests

ZmanimFormatterFormatInstantTest:

• formatsInTheRequestedZone: A UTC formatter formats in UTC, America/New_York and Pacific/Kiritimati. This fails without the fix.
• worksWithAFormatterSetWithoutAZone: A formatter set with setDateTimeFormatter and no zone.

---

🤖 Generated with Claude Code

https://claude.ai/code/session_015Er4Sx7LnKzzCbgDEatxkU