diff --git a/docs/re/METHOD.md b/docs/re/METHOD.md
index dbfeeec1..e8453deb 100644
--- a/docs/re/METHOD.md
+++ b/docs/re/METHOD.md
@@ -1285,3 +1285,33 @@ across geometries. Nobody was looking for that.
 measurement (single-channel, plate-crop) *and* the published figure had a real flaw.
 "One of us must be right" was never the shape of it — which is worth remembering
 before spending a round arguing about which.
+
+## A rule learned from a burn generalises to cases that LOOK like the burn, not to cases that share its mechanism
+
+Contributed by the port agent, and it is the sharpest thing either of us has put in
+this file.
+
+This file already carries **two** divisor bugs, both the same shape: a silent input
+sitting in a divisor and attenuating real signal. The lesson taken from them was
+roughly *"be suspicious of dividing by N"*. So when the intro's three streams had to
+be combined, the port summed at **unity** — and its own checker rejected the tree at
+**+2.62 dBFS**.
+
+🔴 **The precedent did not transfer, and the surface shape is why it looked like it
+would.** Both cases are "several streams, one output". But:
+
+* a BGM bank's two waves are **stems of one signal** — parts that were split apart
+  and must be added back;
+* the intro's three streams are **positions in a field** — a stereo downmix weights
+  them 0.4142 / 0.2929 / 0.2929, which **sum to one whatever the assignment**, so
+  the total is fixed even when the placement is unknown.
+
+Divide-by-N is neither right nor wrong in itself. It depends on whether the inputs
+are parts of one *signal* or parts of one *field*, and nothing in the phrase
+"several streams, one output" distinguishes those.
+
+⚠️ **The general failure**: a rule extracted from a specific burn tends to be indexed
+by *what the burn looked like* rather than by *why it happened*. It then fires on the
+next thing with the same silhouette — and, worse, feels well-earned while doing it.
+When reaching for a past lesson, state the mechanism it turned on and check that
+mechanism is present, not the resemblance.