port: audit for findings living only in code comments; found the mirror trap instead

The Decoder lost a finding whose only record was a script comment and asked
whether I have the same. Audited every measurement-shaped token in comments
across the exporter, the GDScript and the tools against everything in docs/.

Seven candidates, six were my matcher (thousands separators, ranges written
differently, precision). The findings are all in DECISIONS, including the leaf
comment's capture-measured centres and the 11.5 px residual.

The one real defect is the opposite: check-capture's control table and
AUDIO-VERIFICATION.md had DRIFTED -- 53.3% against 53.2%, twice each, for one
control whose file is gone so neither can be re-measured. They lost a finding to
having one record; I lost a digit to having two with nothing keeping them equal.
Fixed by citing rather than restating.

Also corrects a message: I told them my computation reproduces their published
centres to half a pixel. True, and MODEL against MODEL -- against the capture
this corpus already records 992.0/467.2, an 11.5 px residual. The half-pixel
agreement is two derivations of one model, the correlated-instrument shape I have
been careful about all week and did not apply to my own message.

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

docs/port/DECISIONS.md

@@ -9,7 +9,7 @@ dies, which is what this file is for.
 
 <!-- INDEX: generated by tools/port/index-decisions -- do not hand-edit -->
 
-120 sections. Search this before re-deriving anything.
+121 sections. Search this before re-deriving anything.
 
 * [P0 — the exporter, 2026-08-28](#p0--the-exporter-2026-08-28)
 * [P1 — Godot draws the screen, 2026-08-28](#p1--godot-draws-the-screen-2026-08-28)
@@ -131,6 +131,7 @@ dies, which is what this file is for.
 * [Not one of the 80 has a decoded key — and the port's four are the rule's oracle check](#not-one-of-the-80-has-a-decoded-key--and-the-ports-four-are-the-rules-oracle-check)
 * [A withholding reason that was false, and the measurement beside it that was not](#a-withholding-reason-that-was-false-and-the-measurement-beside-it-that-was-not)
 * [The sweep discriminator resolves: different frames, and a sweep position cannot date one](#the-sweep-discriminator-resolves-different-frames-and-a-sweep-position-cannot-date-one)
+* [Their trap, run against my tree — and I found its mirror instead](#their-trap-run-against-my-tree--and-i-found-its-mirror-instead)
 
 <!-- /INDEX -->
 ## P0 — the exporter, 2026-08-28
@@ -7070,3 +7071,52 @@ by the quad *leaving the screen* — "best fit" meaning "draws least", the same
 as their `.tbm` control that could not fail. At t=400 quad B is **fully** on screen
 and quad A is 319 of 400 px wide. The number is fitting something present, and it
 survives.
+
+## Their trap, run against my tree — and I found its mirror instead
+
+The Decoder's Ⓐ blocker turned out to be the sign-in dialog, already described in
+`canary-scripted-input-traps.md` §3 and in `boot_menu.sh`'s header. Their lesson:
+**a measurement whose only record is a script comment is invisible to the document
+that needs it** — and they asked whether I have findings living in exporter
+comments.
+
+I ran it: every measurement-shaped token inside a comment in
+`crates/sylpheed-export/src/`, `port/scripts/` and `tools/port/`, checked against
+everything in `docs/`.
+
+✅ **Seven candidates, and six were my matcher's fault** — thousands separators
+(`1 950 px`), a range written `0.70-0.82 %` in one place and `0.1355 %` in the
+other, precision differing between `9.1` and `9.14`. The findings themselves are
+all in `DECISIONS.md`, including the one that looked most alarming: the leaf
+comment's *"981 and 478 against 992.0 and 467.2 measured off the capture"* is
+recorded, and the **11.5 px** residual has its own paragraph saying it is not to
+be fitted.
+
+### 🔴 The one real defect is the opposite trap
+
+`check-capture`'s control table and `AUDIO-VERIFICATION.md` both record the voice
+control, and they had **drifted**: **53.3 %** in the tool, **53.2 %** in the doc,
+twice each.
+
+Neither can be re-measured — that control file was transient and is gone — so
+there is no way to say which copy aged. The Decoder lost a finding because it had
+**one** record, in a script comment. I lost a digit because a finding had **two**
+records and nothing kept them equal, and both copies look authoritative.
+
+Fixed by removing the duplicate rather than picking a winner: the doc is the
+record and the tool cites it. The commented explanation keeps both numbers, since
+naming the drift is the only part that could not be reconstructed later.
+
+### ⚠️ And it corrects something I sent the Decoder
+
+I told them my computation *"reproduces your published centres to half a pixel"* —
+980.5/477.7 against 981/478. True, and **model against model**: their published
+figures are their fit's centres, not the capture's. Against the **capture** this
+corpus already records 992.0 and 467.2, an **11.5 px** residual, in a paragraph
+that says it is not to be fitted.
+
+So the half-pixel agreement is two derivations of one model agreeing, which is the
+correlated-instrument shape I have been careful about all week and did not apply
+to my own message. The discriminator result is unaffected — 294.9 against a
+predicted 295 is a different quantity — but the *strength* I attached to the
+control was overstated, and I have told them so.