re: a second JP capture closes the transfer -- and corrects my own noise claim

Last turn I transferred the EN title's capture noise to the JP box and flagged
the gap: build 7 carries ptloop01/02.rat which may animate inside that region
where the EN plate does not, and the era adjudication rests on a single capture.
Took a second, independent capture from a fresh boot in a separate session
(jp_title_session.sh -- sets ja, captures, always restores en; verified back at
language=1).

Within-run stability reproduces: 0 of 138 600 px in the ROI across four
comparisons, with 47k-73k px moving whole-frame as the contrast control.

BETWEEN SESSIONS, inside the box the adjudication uses: 645 of 164 124 px
differ, RMSE 0.3215, against 116 492 px whole-frame -- genuinely different
sessions. And the verdict reproduces to three decimals: stale 58.412 -> 58.413,
fixed 41.690 -> 41.692, margin 16.722 -> 16.721.

The shape is the useful part: capture noise moves both candidates together, so it
nearly cancels in a MARGIN. Absolute scores moved 0.001-0.002 while the margin
moved 0.001 against an in-box noise of 0.32. A margin between two renders scored
on one capture is far more robust than either score is.

CORRECTION to a claim I made earlier today and sent to the port: I said the
settle-vs-rest negative was STRENGTHENED because 1.48 sits below the whole-frame
capture spread of 2.8. Wrong comparison -- the measurement lives in the box, and
in-box between-session noise is 0.32, so 1.48 is well above it. The negative
rests on the render axis alone (1.2, ratio 1.2x), exactly as first stated. I
reached for a number that was to hand rather than the one that applies, which is
the same family as the errors we have both been cataloguing.

METHOD gains: match the noise floor to the quantity, including which noise
applies; and sylpheed-port's point that an instrument which rounds away the thing
being verified cannot verify it (they called a harness reproducible from an RMSE
printed to two decimals when the residual was 0.0565).

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

docs/re/data/jp-title-at-rest.txt

@@ -43,3 +43,34 @@
 # the ptlogo3a/b/c + ptlogo_back2eff* stack, which ui-forced-backdrop and
 # the tie-break work record as TRANSPARENT at rest on the English title.
 # That is exactly the region the port's drift is localized to.
+
+################################################################################
+# SECOND, INDEPENDENT CAPTURE -- 2026-08-30, a fresh boot in a separate session.
+# tools/re-capture/jp_title_session.sh (sets ja, captures, ALWAYS restores en).
+#
+# Why: the five frames above demonstrate the logo stack is at rest WITHIN a run.
+# They say nothing about the axis sylpheed-port's drift was on -- BETWEEN runs,
+# where a free-running clock lands somewhere else on a fresh boot. Nothing in
+# this corpus covered that axis, and the ptlogo_eff3 era adjudication rests on
+# a single capture.
+#
+# Within-run stability REPRODUCES in session 2:
+#   ROI 350x396 at (405,74): frames 1-4 vs 0, max |d| 0, 0 / 138 600 differing
+#   whole frame contrast:    47 278 / 51 034 / 58 922 / 72 958 px moving
+#
+# BETWEEN SESSIONS, inside the 388x423 box the era adjudication uses:
+#   645 of 164 124 px differ, max |d| 41, RMSE 0.3215
+#   whole frame, for contrast: 116 492 px differ, max |d| 51
+#   -- so the two captures are genuinely from different sessions.
+#
+# THE VERDICT REPRODUCES TO THREE DECIMALS:
+#                              vs session-1 capture   vs session-2 capture
+#   stale era rest (108,72)          58.412                 58.413
+#   fixed era rest  (98,42)          41.690                 41.692
+#   margin                           16.722                 16.721
+#
+# 📌 And the shape of that is the useful part: capture noise moves BOTH
+# candidates together, so it very nearly cancels in a MARGIN. The absolute
+# scores moved 0.001-0.002 between sessions and the margin moved 0.001, against
+# an in-box capture noise of 0.32. A margin between two renders scored on one
+# capture is far more robust than either score is.