Fix Daf Yomi Yerushalmi cycle boundaries and skipped-day drift#268
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KosherJava merged 1 commit intoKosherJava:3-0-modernizationfrom May 3, 2026
Merged
Fix Daf Yomi Yerushalmi cycle boundaries and skipped-day drift#268KosherJava merged 1 commit intoKosherJava:3-0-modernizationfrom
KosherJava merged 1 commit intoKosherJava:3-0-modernizationfrom
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## Summary This fixes Daf Yomi Yerushalmi calculation bugs around cycle boundaries and skipped days. The previous implementation could return `null` on the first day of a new cycle, and could drift by one daf in later cycles because cycle lengths and skipped days were handled inconsistently. ## Bugs Fixed The first issue was an exact cycle-boundary bug. For example, `1984-05-13` should be the first day of the next Yerushalmi cycle, returning `Berachos 1`. Instead, the calculator treated it as still belonging to the previous cycle. Since the offset was exactly one past the final daf, no masechta matched and the method returned `null`. The second issue was skipped-day drift. The calculator counted special days using a strictly-between range and used the nominal `9 Av` date rather than the observed fast date when Tisha B’Av is delayed. Over many cycles, this could shift the computed daf by a day.
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Summary
This fixes Daf Yomi Yerushalmi calculation bugs around cycle boundaries and skipped days. The previous implementation could return
nullon the first day of a new cycle, and could drift by one daf in later cycles because cycle lengths and skipped days were handled inconsistently.Bugs Fixed
The first issue was an exact cycle-boundary bug. For example,
1984-05-13should be the first day of the next Yerushalmi cycle, returningBerachos 1. Instead, the calculator treated it as still belonging to the previous cycle. Since the offset was exactly one past the final daf, no masechta matched and the method returnednull.The second issue was that we were not taking into account the fact that Tisha B'Av can sometimes be on the tenth of Av.