fix: correct sub-hour timezone drift in getETDate#462
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jonwiggins merged 1 commit intojonwiggins:mainfrom Apr 20, 2026
Merged
fix: correct sub-hour timezone drift in getETDate#462jonwiggins merged 1 commit intojonwiggins:mainfrom
jonwiggins merged 1 commit intojonwiggins:mainfrom
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The two-pass drift correction used setHours() (local time) and only accounted for whole-hour drift. On systems with sub-hour UTC offsets (e.g. IST = UTC+5:30) this introduced a 30-minute error, causing off-peak transition times to be calculated incorrectly. Fix: use setTime() with a millisecond-precision drift that includes the minute component from getETComponents. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
This was referenced Apr 20, 2026
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May 5, 2026
The two-pass drift correction used setHours() (local time) and only accounted for whole-hour drift. On systems with sub-hour UTC offsets (e.g. IST = UTC+5:30) this introduced a 30-minute error, causing off-peak transition times to be calculated incorrectly. Fix: use setTime() with a millisecond-precision drift that includes the minute component from getETComponents. Co-authored-by: Ramesh Nethi <r.nethi@gogatewayai.com> Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>
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Summary
Fixes off-peak time calculation errors on systems with sub-hour UTC offsets (e.g., IST = UTC+5:30). The existing drift correction used
setHours()which only accounted for whole-hour offsets, introducing a 30-minute error for sub-hour timezones.Changes
packages/shared/src/utils/off-peak.ts: ReplacesetHours()drift correction withsetTime()using millisecond-precision calculationgetETComponentsin drift calculation to handle sub-hour timezone offsetsTesting
pnpm turbo test)pnpm turbo typecheck)Tested on IST (UTC+5:30) system where off-peak transition times were previously off by 30 minutes.
Related
Discovered during local development on system with sub-hour UTC offset.