diff --git a/docs/re/METHOD.md b/docs/re/METHOD.md
index dda120b8..7ec3e62e 100644
--- a/docs/re/METHOD.md
+++ b/docs/re/METHOD.md
@@ -2573,3 +2573,38 @@ is still no hardware rate here) but it survived by luck: I had asserted the stro
 form from a single probe. ⚠️ **A negative needs its reach stated at the moment it
 is written** — "not at this path" is what I measured; "not present" is what I
 wrote.
+
+## An instrument answering with a property of itself — now four instances
+
+`sylpheed-port` names this as a family after their correlation returned **+2413
+against a window of ±2400** — its own boundary, not a peak. The instances so far,
+across two agents, two languages and four tools:
+
+| | instrument | answered with |
+|---|---|---|
+| 1 | my period estimator | **0.599 s**, its own search floor |
+| 2 | their alignment search | **+2413**, its own window edge |
+| 3 | their `--leaf-time` sweep | a state the screen never occupies |
+| 4 | my `main_menu_item` before it refused | a row **two items** off, inside a tolerance too loose to notice |
+
+📌 **The control caught every one of these and nothing else would have.** None
+looked wrong: a number at a boundary is still a number, and three of the four were
+printed beside plausible companions.
+
+⚠️ **The cheap defence is to make the boundary visible in the output** — report
+the search range beside the answer, so "0.599 in [0.6, 8.0]" reads as the failure
+it is rather than as a measurement. The stronger one, which cost me a wrong session
+to learn, is to have the instrument **refuse**: `ring_row.py` returns nothing when
+the row is not within half a step of a calibrated centre.
+
+## When two attempts disagree, change the KIND of quantity, not the parsing
+
+Measuring whether `-ss` before `-i` overshoots, I read a `-vstats` line as a
+timestamp, then used `showinfo` with an output-side `-ss` — which reports frames
+from *before* the discard, so every cell read 0. **Both produced confident-looking
+tables.** What settled it was dropping timestamp semantics entirely and comparing
+**pixels**, which need no interpretation.
+
+📌 Two failed attempts at the same measurement are evidence that the *quantity* is
+the problem, not the parsing of it. The third attempt should change what is being
+measured.