`RRule.after`, `Rule.before` ignoring EXDATE when using caching

[erikvdplas]

I came accross this issue with the following (simple) rule set, i.e. a monthly recurrence with one exception for April 1st, 2026:

DTSTART;TZID=Europe/Amsterdam:20260101T163000
RRULE:FREQ=MONTHLY;INTERVAL=1
RDATE;TZID=Europe/Amsterdam:20260327T093000
EXDATE;TZID=Europe/Amsterdam:20260401T163000

When I use set.all() it correctly omits the April date, and includes the 'replacement' March 27, 2026. However, when I check the following, it gives an unexpected result:

const aprilOccurrence = new Date('2026-04-01T16:30:00.000Z')
ruleSet.after(aprilOccurrence, true)

> 2026-04-01T16:30:00.000Z

Similar behavior occurs when using Rule.before or even Rule.between.

This seems like a bug to me, any chance I might be missing something? Would love to help if possible, but first I am curious to hear from regular maintainers here what might be at play and if this is indeed unexpected behavior.

[erikvdplas]

I found out that explicitly disabling cache on my ruleset fixes this issue. In my specific case, the rule set is constructed by first copying rules from an existing rule set (which only contains the regular monthly occurrence), and then adding the rdate and exdate. Might help with investigation. So far I couldn't find anything why this behavior should break with caching enabled.