re: a .tbm DRAWS -- the TUTORIAL screen captured, and the 'inert' reading refuted

Closes the open second reading in ui-forced-backdrop.md: that a .tbm contributes
no pixels, leaving 24 of its 62 deciding verdicts harmless rather than correct.

The TUTORIAL screen was reached and captured. It carries a full-screen blue
circuit/hex background. GP_TUTORIAL build 0's element 0 is pubase.tbm with pivot
(640,360) -- 1280x720, the only full-screen TEXTURED element in the bundle; the
one other full-screen element is pueff00.prm, an untextured primitive the colour
census puts at pure black. Our render of the same build is the identical layout
on pure black, 6.0-6.4 % inked against the game's 99.7 %. The only difference is
the background and the only thing it can be is the .tbm.

So the 24 .tbm verdicts are correct rather than harmless, and they are
load-bearing in the full sense. Reach: one .tbm observed; the class question is
settled, the ten other families are not individually seen.

Also: screen render is wrong on every screen carrying a .tbm -- it drops the
background silently, with no diagnostic.

And the identification is worth its own METHOD entry. Two statistical identifiers
were built. Masked correlation FAILED its control, picking EXTRAS over the known
main menu by 0.004 because the shared background dominates. A high-passed variant
PASSED by 1.28x, which is not a margin that licenses identifying an unknown, so it
was not used. The screen says TUTORIAL across the top. Ask whether the artefact
already states the answer before building a matcher.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Wuu56cE8vJGTBtn1ppsk8v

docs/re/structures/tbm-submenu-not-reached.md

@@ -1,4 +1,4 @@
-# 🟡 Does a `.tbm` draw pixels? Still open — but a submenu is now REACHED
+# ✅ A `.tbm` DRAWS PIXELS — the `TUTORIAL` screen, captured and identified
 
 **Classification: not an answer.** Recorded per *"do not improvise around a
 blocker"*, and because the *reason* both runs failed is the same mistake three
@@ -79,7 +79,29 @@ a confident wrong answer.
 
 So two of the three render essentially nothing where the game draws a full screen.
 
-## 🔴 But which screen this is, is NOT established — and the reason is a method point
+## ✅ It is `TUTORIAL`, and the screen names itself
+
+**Read off the framebuffer** — the same method Q4 used to measure all five menu
+buttons. The capture says `TUTORIAL`, lists `BASIC CONTROLS … BACK`, and carries a
+**full-screen blue circuit/hex background**.
+
+`GP_TUTORIAL` build 0's element 0 is **`pubase.tbm`, pivot (640, 360)** — 1280×720,
+the only full-screen *textured* element in the bundle; the one other full-screen
+element is `pueff00.prm`, an untextured primitive that the colour census puts at
+**pure black**. Our render of the same build is the **identical layout on pure
+black** — 6.0–6.4 % inked against the game's 99.7 %.
+
+**So a `.tbm` draws, and the "inert" reading in
+[`ui-forced-backdrop.md`](ui-forced-backdrop.md) is refuted.** Its 24 `.tbm`
+deciders are correct rather than harmless. ⚠️ One `.tbm` observed; the class question
+is settled, the ten other families are not individually seen.
+
+🔴 **And `screen render` is wrong on every screen carrying a `.tbm`** — it drops the
+background silently.
+
+## 🔴 The instrument I built for this failed, and reading the screen was better
+
+**Correlation cannot discriminate when the candidate renders are near-blank.**
 
 **Correlation cannot discriminate when the candidate renders are near-blank.** An
 almost-empty image has no structure to correlate against, so all 19 `GP_SAVE_LOAD`
@@ -88,6 +110,15 @@ matching statistic is useless against a hypothesis that predicts an empty image*
 and that is precisely the hypothesis under test. The instrument is disabled by the
 thing it was brought in to detect.
 
+🔴 **Two repair attempts, and the honest outcome.** Masking the correlation to the
+pixels the render *does* ink **failed its control**: asked to identify the known main
+menu, it picked `EXTRAS` over the menu by **+0.0040** — the shared background
+dominates. High-passing first **passed** the control but by **1.28×**
+(+0.0276 against +0.0215), where the port's method on the same class of problem
+separated by 4.7×. **A control that passes by 1.28× is not a licence to identify an
+unknown**, so it was not used. Looking at the picture settled in one step what two
+statistics could not.
+
 🔴 **And the focus could not be read either.** Against the two labelled menu
 captures the whole-frame mean absolute difference is **2.52** (NEW GAME) and
 **2.48** (OPTIONS) — 1.6 % apart, far too weak to call.