react-big-calendar: Recurring vs One-Off Event Rendering

Problem

react-big-calendar requires pre-generated event objects with specific start and end Date instances. When your data includes both recurring events (e.g., "every Monday 9-5") and one-off events (e.g., "January 15, 2026 only"), a naive "anchor to current week" approach causes one-off events to appear every week instead of just their specific date.

Additionally, recurring events may have date constraints (effectiveFrom/effectiveUntil) that aren't respected, causing them to appear before they start or after they end.

Context / Trigger Conditions

Use this skill when:

1. One-off events repeat incorrectly: An event with effectiveFrom: 2026-02-15 and effectiveUntil: 2026-02-15 appears on Feb 15, Feb 22, Feb 29, etc. (every week)

2. Recurring events ignore date ranges: A recurring Monday event with effectiveFrom: 2026-03-01 appears on Mondays in February

3. View range issues: Calendar only shows events for the current week, even in month view