docs(773): #767 closed 19 minutes after the corpus snapshot — state the boundary, use its record

Caught by the user. 3.7 said #767 "was still open when the corpus was drawn, so
it has no `## Closing record`." First half true, second half stale within the
hour: the corpus was drawn 19:45, #767 closed 20:04, and it now carries a full
closing record. A claim that was true when written and silently stopped being
true — the exact class this document ranks 7th — inside the sentence
complaining that #767 was missing.

Fixed by stating the snapshot boundary rather than softening the claim: the
corpus is a 19:45 snapshot, #767 is excluded by timing, and it is named as an
exclusion instead of quietly folded in, because re-drawing would move every
denominator in 2 and 3.6 and the boundary has to sit somewhere. The header now
carries the snapshot time, not just the date.

Reading its record strengthens Family A rather than complicating it. #767
reinvents detector A independently — the fifth and sixth times in this repo:
"Refuting two variants of a channel is not clearing the channel" (the working
attacks through that channel were never tried), and "Enumerating SHAPES of a
command loses. Nine disarms across two rounds; running the command settles them
together." The latter is detector A in a sentence.

Refs #773

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

docs/defect-shapes-773.md

@@ -5,7 +5,9 @@ each class, and an audit of the tooling already configured in this repo. This is
 artifact**, not a rulebook: the rules it argues for land as decision records and follow-up issues,
 which are linked per class below.
 
-Measured 2026-08-13 against the tracker as of issue #773 and `origin/main` at `f9f8f65ce`.
+Measured 2026-08-13 against `origin/main` at `f9f8f65ce`. **The issue corpus is a snapshot drawn at
+19:45 that day** — a boundary that matters, because #767 closed nineteen minutes later and is
+therefore absent from every count here (§3.7).
 
 ---
 
@@ -274,10 +276,19 @@ the text under review.
 
 - The ≥3-rounds count comes from pattern-matching narrative prose, not from a structured field. It
   under-counts records that ran rounds without narrating them, so 18 is a floor.
-- **#767 — the eight-round case that motivates #773 — is not in this corpus at all.** It was still
-  open when the corpus was drawn, so it has no `## Closing record`. The headline example of the
-  phenomenon is invisible to the measurement characterising it, which is worth stating plainly rather
-  than letting the 18 stand as though it covered the worst case.
+- **#767 — the case #773 describes as taking eight review rounds — is excluded by snapshot timing,
+  not by absence.** The corpus was drawn at 19:45 on 2026-08-13; #767 closed at 20:04, nineteen
+  minutes later, and now carries a full `## Closing record`. So the worst instance of the phenomenon
+  is missing from every count in this document, including the 18 above. It is named here rather than
+  quietly folded in, because re-drawing the corpus would move every denominator in §2 and §3.6 and
+  the snapshot boundary has to sit somewhere.
+
+  Reading its record changes nothing structurally and confirms Family A twice over — it reinvents
+  detector A independently, for the fifth and sixth times in this repo: *"Refuting two variants of a
+  channel is not clearing the channel"* (the working attacks through that channel were never tried),
+  and *"Enumerating **shapes** of a command loses. Nine disarms across two rounds; running the
+  command settles them together."* That last sentence is detector A in one line — stop sampling the
+  shapes you thought of, execute the population.
 
 ---