MCP Time Server Node

# Business Days Calculation with date-fns (Verified 2025-07-18) **Key Findings**: 1. **Built-in Function**: - `differenceInBusinessDays()` exists and counts weekdays between dates - Returns integer (truncated) number of business days - Negative values when end is before start - Does NOT handle holidays - only excludes weekends 2. **Weekend Definition**: - Saturday (day 6) and Sunday (day 0) are weekends - `isWeekend()` returns true for these days - Monday-Friday are business days 3. **Counting Behavior**: - Counts weekdays between start and end dates - Same day = 0 business days - Time components are ignored (only dates matter) - Invalid dates return NaN 4. **eachDayOfInterval**: - Returns array of dates including both start and end (inclusive) - Handles reversed dates (end before start) without error - Returns empty array for invalid dates - Single day interval returns array with 1 date 5. **Holiday Handling**: - Must be implemented manually - Use `isSameDay()` to check if a date matches a holiday - Count holidays that fall on business days separately 6. **Timezone Considerations**: - Business day calculation uses date boundaries - Times in different timezones might span different dates - Use `toDate()` with timezone to interpret local dates - `isSameDay()` compares dates in same timezone 7. **Calendar Days**: - `differenceInCalendarDays()` counts all days - Use for total_days in response - Always compare with business days for weekend count 8. **Implementation Strategy**: - Use `eachDayOfInterval()` to get all dates - Filter with `isWeekend()` for business days - Check against holiday array with `isSameDay()` - Count different categories separately