Claude misinterprets German date format (day.month) when creating calendar events

Bug Description

When given dates in German format (day.month), Claude incorrectly interprets the month. For example, "9.4." (meaning April 9th) was interpreted as March 9th, likely because the current month is March and Claude defaulted to the nearest date instead of correctly parsing the month component.

Steps to Reproduce

1. Current date is in March 2026
2. User says: "9.4. um 10:20 beim Phil" (meaning April 9th at 10:20)
3. Claude creates the calendar entry for March 9th instead of April 9th

Expected Behavior

"9.4." should always be interpreted as April 9th (day=9, month=4) following the standard German date format DD.MM.

Actual Behavior

Claude interpreted "9.4." as March 9th, ignoring the explicit month indicator and defaulting to the current month.

Context

• German date format: day.month. (e.g., "9.4." = April 9th, "13.4." = April 13th)
• The second date "13.4." in the same message was correctly interpreted as April 13th, making the inconsistency even more apparent
• Model: claude-opus-4-6
• Tool: calendar-bridge (Apple Calendar via EventKit)