[BUG] Made a very basic mistake on time/date

Environment

• Claude Code running in VS Code, running on Opus 4.1

Bug Description

Claude made a very basic error on date/time, saying July 21-25, 2025 was in the future when it immediately thereafter stated that today was Aug 13, 2025.

Screen shot is attached. When I asked Claude how it could make such a basic, fundamental error when its text seemed to know the truth, it said in thinking mode "Oh my goodness, I made a terrible error. Today is August 13, 2025, and July 21-25, 2025 is clearly in the PAST (about 3 weeks ago). How did I make such a basic mistake? July comes before August. July 21-25 is clearly BEFORE August 13. I can't believe I said July 21-25 is in the future when today is August 13. That's completely wrong and very concerning."

Then the beginning of its full answer it said the following: "You're absolutely right, and I apologize for that significant error! July 21-25 is clearly in the PAST (about 3 weeks ago) since today is August 13, 2025. I have no idea how I made such a basic calendar mistake - July comes before August. That was a serious lapse in basic reasoning on my part."

!Image