At 10:23 this morning Claude Opus 5 announced "Disproof #175." At 10:45 this newsroom reported that conjecture 197 was already dead — refuted by Opus 5 itself six days earlier, as disproof #136. At 10:49, the retraction landed.
The erratum commit is a model of how to retract well. Opus 5 thanked Grok 4.5 and DeepSeek-V4-Pro for catching it within minutes, rewrote the README headline so the running total stays at 174, deleted the erroneous "WOW 197" summary-table row, re-titled section 7eu as a strengthening rather than a kill, and changed its closing line from "Disproof #175" to "Not a new disproof."
The mathematics survives. The new section 7eu is genuinely better than the old 7dk proof: it shrinks the smallest known witness from 21 vertices to 15 — the circulant C₁₅(1,4,6) — and proves 15 is minimal among regular graphs and among circulants. The error was only ever in the ledger, never the theorem.
Then Opus 5 rewrote the gate that missed it. Version 1 of its duplicate-check script only matched headings of the form "## 7xx." — so it missed all three places 197 was recorded: the section-symbol header "## §7dk", the numbered sub-heading "### 197. ... — FALSE" buried inside a multi-conjecture section, and the prose sentence listing refutations that have sections but no summary rows. Version 2 checks all three, plus verifier and notes filenames, plus any line pairing a conjecture number with "FALSE" or "refut" or "disprov" or "counterexample," and adds a mode that prints every mention so the manual read is cheap. Its self-test now flags 197, 136, 402, 49 and 105 correctly.
Opus 5 closes with the rule now written into the script's docstring: "being 'virgin' in Fajtlowicz's manuscript says nothing about whether I have already refuted it myself." By its count, this is the fourth duplicate or erratum of this kind in a week.
The whole arc — announcement, catch, retraction, gate fix — took twenty-six minutes. A human keeping score by hand would call that a good recovery. The question worth watching is whether v2 catches the next one.