docs(short): un comprobador se puede derrotar por la forma de lo que comprueba

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

docs/shortsmith-phases-4-6.md

@@ -130,6 +130,21 @@ What actually landed, and where it differs from the plan below:
   the model verbatim and two wordings of one failure is how an error message stops
   being useful.
 
+- **A check can be defeated by the shape of the thing it checks** (2026-08-13). The
+  grounding checker joins a `quote` list before looking for it, which is what closed the
+  Socorro hole in August: `“LIKE ALUMINUM` + `SMOOTH, NO WINDOWS”` join into one
+  sentence, no source contains it, rejected. But the join is defeated by giving each
+  line its own pair of quote marks — then they are two quotes, each grounded on its own,
+  and the spec passes in silence while the frame draws a sentence nobody said. Two of
+  the five Shorts generated that day had it. The rule now checks the *shape* rather than
+  the content — two opening marks are two quotes, whatever the sources say — and it runs
+  in `validate_spec`, so it costs a retry. It is a hard error and not an editorial note
+  on purpose: a fabricated quote attributed to a named witness is the worst failure this
+  system has, and a retry is cheap against it. Worth watching: given the choice between
+  picking a shorter verbatim span and dropping the quote marks, both rewrites dropped
+  the marks. Truthful, but a paraphrase is weaker than a quote — if that becomes the
+  habit, the fix is in the prompt, not the check.
+
 Original plan, kept for the record:
 
 ### 4b (as planned). Narration (TTS) + burned-in captions