Fix DST offset applied incorrectly near daylight saving transitions#2357
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…ebastienros#2355) The Utc() method treated local time as a UTC instant when querying GetUtcOffset, causing the wrong DST offset near transitions. Use a two-pass approach matching the ES spec: estimate UTC first, then refine with the correct offset at that UTC instant. Same fix in TryParse for date strings without timezone info. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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March 24, 2026 04:44
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Summary
Utc()method inDatePrototypetreated local time as a UTC instant when queryingGetUtcOffset, causing the wrong DST offset to be used near daylight saving transitions (e.g., midnight in NZ timezone on DST transition days)UTC(t): estimate UTC first, then get the correct offset at that UTC instantDefaultTimeSystem.TryParsefor date strings parsed without timezone infoTest plan
DstTransitionShouldUseCorrectOffsettest covering NZ fall-back (April) and spring-forward (September) transitions🤖 Generated with Claude Code