port: WITHDRAW the 'eras render identically' measurement -- I compared a binary with itself

Last iteration I overturned check-all's allowance on a measurement of 0 pixels
between the two decoder eras, and rewrote the tool's reason around it. The two
binaries had the same md5: one built in a worktree at formats-pin-2026-08-30 and
one from the workspace, and both commits carry the record-layout fix. I compared a
binary with itself and reported the zero as evidence. The 508-line diff I cited
was real and irrelevant -- it does not straddle the fix.

Done properly against origin/main, verified stale by the Decoder's own control
(rest t=70 vs rest t=12) and by differing md5s: title 0 px, main_menu 0 px,
title_jp 74507 px -- reproducing their figure exactly, under their flags and mine.
My second hypothesis, that --animated masked it, was also wrong.

What survives: the era still cannot explain this script's rows, for a fact I had
not established -- both sides of the comparison are the FIXED era, since a binary
built from the pin and one from the workspace have the same md5. Right answer,
wrong evidence. The note now carries its condition: title_jp is era-sensitive, so
if the reference is ever built from a different era than the pin, that row's cause
changes.

Twice now a correct conclusion has come through a broken experiment, and both
times the tell was two things that should differ producing identical output.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01N7FiFFFwbvG2uxdcEh8HyF

tools/port/check-all

@@ -64,18 +64,31 @@ differs=$(grep -c DIFFERS "$OUT/verify-screen.log" || true)
 unexpected=$(grep DIFFERS "$OUT/verify-screen.log" | awk '{print $1}' \
   | grep -vx -e title -e title_jp || true)
 
-# 🔴 THE OLD ALLOWANCE WAS FALSE, AND IT EXCUSED TWO ROWS WITH A REASON THAT IS
-# NOT THE REASON.
+# 🔴 THE OLD ALLOWANCE WAS FALSE, AND MY FIRST REPLACEMENT REASON WAS ALSO
+# WRONG. Both are recorded because the second error is the more instructive.
 #
-# It said: "the pin is not on main, so this compares two decoder eras". Measured
-# 2026-08-30 by building `sylpheed-cli` at `formats-pin-2026-08-30` and at the
-# workspace HEAD and rendering both: `title`, `title_jp` and `main_menu` come out
-# **0 pixels different**, despite 508 lines of difference in `ui_layout.rs`. The
-# eras are not the cause of anything here.
+# It said: "the pin is not on main, so this compares two decoder eras". I
+# replaced that with "the eras render identically -- 0 pixels different on three
+# screens". 🔴 **That measurement was void**: the two binaries I compared had the
+# same md5. I built one in a worktree at the pinned tag and one from the
+# workspace, and both commits carry the record-layout fix, so I compared a
+# binary with itself and reported the zero as evidence.
 #
-# 🔴 And its expiry tested `formats-pin-2026-08-29d` while `Cargo.toml` pins
-# `formats-pin-2026-08-30` -- so the allowance would have expired on a tag this
-# tree does not use, in either direction, silently.
+# Rebuilt properly against `origin/main`, which is the genuinely stale era
+# (`rest t=70 [12 70 80 -]` against the fixed `rest t=12 [0 12 70 80]`):
+#
+#   title      0 px      main_menu  0 px      title_jp  74 507 px
+#
+# ✅ The eras DO change pixels, and `title_jp` is one of the seven bundles where
+# they do -- reproducing the Decoder's figure exactly, under their flags and
+# mine. My "--animated masks it" hypothesis was wrong too.
+#
+# ✅ BUT THE ERA STILL CANNOT EXPLAIN THIS SCRIPT'S ROWS, for a reason I had not
+# established: BOTH SIDES OF THIS COMPARISON ARE THE FIXED ERA. The exporter is
+# pinned to `formats-pin-2026-08-30` and this reference is built from the
+# workspace, and a binary built from each has the SAME md5. There is no era
+# mismatch here to explain anything. Right answer, wrong evidence, and the wrong
+# evidence was a broken experiment.
 #
 # The real reasons are per-screen and already documented:
 #   title    -- the ptloop SWEEP PHASE residual, max 6 / over3 790, unchanged
@@ -83,8 +96,10 @@ unexpected=$(grep DIFFERS "$OUT/verify-screen.log" | awk '{print $1}' \
 #   title_jp -- the `--pose=rest` sparkle handling. Adjudicated against the
 #               oracle: the port's SHIPPED pose scores r +0.9994 against the
 #               game where the reference scores +0.8727, and `--pose=rest` is
-#               what this script compares. The port is closer to the game on the
-#               row this script calls a disagreement.
+#               what this script compares.
+#   ⚠️ title_jp is ALSO an era-sensitive bundle, so if this reference is ever
+#   built from a different era than the exporter's pin, that row's cause changes
+#   and this note stops applying. Check the md5s before trusting it again.
 #
 # So the allowance is now a NAMED SET, not a count with an excuse. A DIFFERS on
 # any other screen fails the run, which a count never could.