diff --git a/docs/re/METHOD.md b/docs/re/METHOD.md
index 76997d4e..da345d6b 100644
--- a/docs/re/METHOD.md
+++ b/docs/re/METHOD.md
@@ -1372,3 +1372,36 @@ crate's fixed output, so a fault in the fix would reproduce. Recorded at that
 strength and no higher. The distinction worth keeping: *a different asset* is real
 evidence about generality; *a different implementation* is what makes it independent,
 and only one of those two was present.
+
+## The instrument can be sound, the number correct, and the sentence around it wrong
+
+Almost everything else in this file is about a broken or misspecified instrument.
+This one is different, and the port agent named it after hitting it twice in a
+fortnight:
+
+* it measured a **3.4 s near-silent seam** in its menu bed — correctly — and wrote
+  it up as *"the cost of the missing loop point"*. The seam was real; it was
+  produced by **our own loop**, and the game has none. It then reached a
+  `BLOCKED.md` entry and a message to me, both carrying the wrong cause.
+* it measured a leading chunk correlating at **r=0.998** with another stream's tail
+  — correctly — and called it *a duplicate*. It was a **start-truncated simultaneous
+  stream**, and the flush-against-the-end alignment is exactly what truncation
+  predicts.
+
+Both times the number survived scrutiny and the **attribution** did not.
+
+⚠️ **No amount of instrument control catches this.** Controls test whether the
+measurement is faithful; they say nothing about the clause that follows it. The
+defences that do work are different in kind:
+
+* **name the alternative explanation explicitly** and say why it is excluded — "a
+  seam because we loop wrongly" was never written down as a candidate, so it was
+  never rejected;
+* **notice when a measurement is being used to explain something it did not
+  measure.** The seam was measured *in our output*; the sentence made a claim about
+  *the game*. That step is where the error lives, and it is invisible while the
+  number stays in view.
+
+📌 A useful smell: a measurement that arrives already attached to a cause, and
+whose cause happens to be the thing you were hoping to justify — a missing field, a
+duplicate worth dropping. Both of these did.