diff --git a/docs/re/structures/ui-resting-pose.md b/docs/re/structures/ui-resting-pose.md
index b825d9a0..7c06ada8 100644
--- a/docs/re/structures/ui-resting-pose.md
+++ b/docs/re/structures/ui-resting-pose.md
@@ -145,6 +145,48 @@ component isolated in a renderer, mine is everything that varies between session
 includes theirs. Anyone quoting a whole-frame number on this screen should use the
 larger figure.
 
+### 🔴 The crop is NOT why the box is robust — and that questions "the leaf free-runs in the game"
+
+`sylpheed-port` could not transfer the masking rule to their screens and inferred
+a precondition: *my* free-running element is a localised plate I can crop around,
+theirs is a wide sweep they cannot. **Tested, and that is wrong about my case.**
+The JP title carries the *same* sweep — the leaves are identical on entries 4, 5
+and 7 — and it crosses the box:
+
+```
+two renders of build 7 on the settled plateau, t=135 vs t=240
+  whole frame  RMSE 12.135   95 791 px differ
+  in the box   RMSE 11.923   57 981 px      <- the sweep is INSIDE the box
+  differences span y 70..674, x 128..1140;  the box is y 54..476, x 389..776
+```
+
+So cropping did not exclude the mover, and the in-box between-session term of
+**0.3215** is not explained by the crop. That leaves a real tension:
+
+* two **renders** one plateau-phase apart differ by **11.9** inside the box;
+* two **captures** of that screen, different sessions, differ by **0.32** there;
+* and the `--at` sweep of renders against a capture is **flat to 1.2** across
+  t=135..240, despite those renders differing from each other by 11.9.
+
+A metric cannot be insensitive to a 11.9 change unless the thing that changed is
+largely absent from what it is being compared against.
+
+🟡 **Hypothesis, untested: the game may not draw these leaves on the settled title
+at all** — our renderer poses them wherever `--at` says, the game shows none of
+it. That would explain the flat plateau, the tiny between-session term, and part
+of the ~40 residual in one move. ⚠️ It would also mean `sylpheed-port`'s "the leaf
+free-runs in the game too" is **not established by their evidence**: their two
+minima come from two *different screens*, which can differ for reasons other than
+a free-running phase. My two captures are of the **same** screen and barely differ
+where the sweep would be.
+
+I am not claiming the leaves are invisible — that needs a capture-side test
+(a draw-stream check for `pteff03`/`pteff03a` on a settled title would settle it in
+one run). What is established is narrower and enough to stop the inference: **the
+box's robustness is not the crop, so no precondition about compactness explains
+it, and the phase term for captures of this screen is measured at 0.32 while the
+term for renders of it is 11.9.**
+
 📌 **And it is why the box matters more than I realised when I chose it.** Scoring
 the 388×423 region rather than the frame drops the between-session term from 4.566
 to **0.3215** — a factor of 14 — because the sweep contributes at x 721..1241 and