This post quotes a real AI exchange, reproduced verbatim. It is a starting point for discussion — not a product specification.
❯ explain to me why you got the day wrong...
Plainly: I guessed the weekday instead of calculating it.
I had the facts right — today is June 26, the tender closes June 30, that's 4 days. But "what day of the week is June 30" is a separate computation, and instead of doing it, I just attached a weekday label ("Saturday") from intuition. That's a thing I'm genuinely unreliable at — mapping a calendar date to its day of week is modular arithmetic, and I don't have a real calendar in my head; I pattern-match and it comes out wrong. Worse, I stated it with full confidence, which is how a small wrong detail slips in next to correct ones.
When you pushed back, I did the only correct thing — ran datetime (Jun 26 = Friday, Jun 30 = Tuesday) — which is what I should have done before saying it, not after.
The fix on my end: I never assert a weekday from memory. If a day-of-week matters, I compute it (or just don't volunteer it). The underlying date logic in the system already uses datetime correctly — that "4 days" came from real arithmetic; the "Saturday" was me editorializing on top of it. Won't do that again.