What we
got wrong.
And fixed in public.
A site that never publishes its errors has twice as many: the ones it makes, and the ones it hides. The Erratum keeps the trace of all of ours. We come back to it when we must; we remove nothing.
- 012026-05-14· The Criée
The Criée of May 14 was poorly phrased
The question asked for “the right answer” when none existed without session context. Rephrased on May 15. Answers from the 14th are preserved: the question was at fault, not the reader.
- 022026-04-02· Lesson
Lesson “psy-03” — wrong figure on average hold time
The figure given (“6 days on average”) came from a sample that was too short. Replaced with “observed range: 2 to 11 days, no stable mean.” The sentence is longer; that is the cost of honesty.
- 032026-03-21· Site
A reader’s progress could appear on another account
A local scoping flaw left the first signed-in account’s progress visible after a second account signed in on the same machine. Fixed by hashing the signed-in email into every storage key. No server data was affected.
- 042026-02-09· The Letter
The Sunday Letter double-counted some reviews
The “What returns” section was counting a mistake reviewed on Sunday as both “reviewed this week” and “due next week.” Filter adjusted; past Letters remain as they were read.
- 052026-01-30· Method
The Score formula was simplified — silently, which was a fault
We adjusted the weighting of the “regularity” component without saying so. The new formula is better; the silence was not. Details published on the method page on February 1.