port: the P1 regression harness could not have run since the monorepo merge

verify-screen resolves its reference binary to a path build-reference-cli
stopped being able to produce: that script greps Cargo.toml for a
`Syplheed-Reborn.git", rev = "..."` pin, and 65cefa7 replaced it with a path
dependency. The grep returns nothing, the script exits 1, and the binary left
behind predates the merge -- three hours older than the sources, from a revision
nothing points at. The consumer only checked that the file EXISTED.

DECISIONS already carries "the reference renderer was stale for three diff runs"
from P2. This would have been the fourth, by a different mechanism: not a
forgotten rebuild but a build step that could no longer succeed.

The fix is a deletion. Revision-keying solved a two-repo problem -- /reborn's
target/ was a live mount that moved mid-run -- and the monorepo removed that
problem by construction. verify-screen now builds sylpheed-cli from the
workspace, which is the same decoder the exporter and the port read.

BASELINE, all 16 screens, after four milestones of renderer change: no new
drift. The only substantial disagreement is title_jp (max 155, 20498 px), which
is the same one P1 recorded and left open -- ptlogo_eff2 at 125 % scale, where
blit samples the destination pixel's corner and a GPU samples its centre. The
port still does not match it, because matching means reproducing a half-pixel
bias on purpose to make a number smaller.

`max` alone could not tell 2 pixels from 25 000: main_menu and title_jp produced
the same DIFFERS verdict. The script now also reports how many pixels are over
the bar. The bar is NOT raised -- tuning a threshold until things match is the
failure its own header warns about.

Stated plainly because sixteen OK rows look reassuring: the harness renders
--pose=rest, so NONE of the last four milestones' visible work is under test --
not the spinning ring, not the plate composite, not any timeline behaviour, not
audio.

REFUTATION: the RE agent's answer naming "builds 0/1 and 10/11" as the loading
screen is false in the index space this export uses -- entries 10 and 11 are
palogo_sqex and palogo_gamearts, the splashes, which the same agent identified
as such answering my ask 1. Over the twelve is_build bundles, ordinals 10/11 ARE
entries 12/15, so the finding is right and the enumeration is not mine.
authored/screen_names.json is keyed by ENTRY, and someone writing keys "10" and
"11" from that message would name the publisher wordmark and the developer logos
as loading screens, and everything would still validate and run.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01WM5XL4HfrHuxz8RiMWdCMC

tools/port/verify-screen

@@ -53,15 +53,39 @@
 set -euo pipefail
 cd "${PROJECT_DIR:-/work}"
 
-# `reference-cli/`, not `release/`: the reference binary is built per pinned
-# revision so a pin change cannot silently reuse the previous revision's build.
-# See docker/bin/build-reference-cli.
-CLI="${SYLPHEED_CLI:-${CARGO_TARGET_DIR:-/sylph-home/port/target-container}/reference-cli/sylpheed-cli}"
+# THE REFERENCE IS THE WORKSPACE'S OWN `sylpheed-cli`, and that is a change.
+#
+# It used to be a binary built per PINNED REVISION into `reference-cli/<rev>/`,
+# because `sylpheed-formats` was a git dependency and /reborn's target/ was a
+# live mount of the other agent's checkout that moved mid-run. A pixel
+# disagreement against a moving decoder has a free variable in it.
+#
+# The monorepo merge (`65cefa7`) removed that problem by construction:
+# `crates/sylpheed-export/Cargo.toml` now says
+# `sylpheed-formats = { path = "../sylpheed-formats" }`, so the exporter, this
+# reference and the port all read ONE decoder -- the working tree's.
+#
+# 🔴 It also silently broke the old machinery, and this script did not notice.
+# `build-reference-cli` greps Cargo.toml for `Syplheed-Reborn.git", rev = "..."`;
+# that line no longer exists, so the script exits 1 and the binary at
+# `reference-cli/sylpheed-cli` is whatever was last built before the merge --
+# here, three hours older than the sources and from a revision nothing points
+# at any more. Running the diff against it would have compared the port to a
+# decoder from another era and called the result a regression check. This
+# corpus has already been bitten by a stale reference renderer three times.
+#
+# So: build it from the workspace. `SYLPHEED_CLI` still overrides, for anyone
+# who does want to pin one deliberately.
+CLI="${SYLPHEED_CLI:-}"
+if [ -z "$CLI" ]; then
+  CLI="${CARGO_TARGET_DIR:-/sylph-home/port/target-container}/release/sylpheed-cli"
+  cargo build --release -p sylpheed-cli >/dev/null 2>&1 || true
+fi
 DISC="${SYLPHEED_DISC:-/disc}"
 OUT="${OUT:-${TMPDIR:-/tmp}/verify-screen}"
 export DISPLAY="${DISPLAY:-:97}"
 
-[ -x "$CLI" ] || { echo "no reference CLI at $CLI -- run build-reference-cli" >&2; exit 2; }
+[ -x "$CLI" ] || { echo "no reference CLI at $CLI -- \`cargo build --release -p sylpheed-cli\` failed?" >&2; exit 2; }
 [ -f export/manifest.json ] || { echo "no export/manifest.json -- run build-export --run" >&2; exit 2; }
 mkdir -p "$OUT"
 
@@ -98,12 +122,24 @@ print(json.load(open("export/"+f))["source"]["build"])' "$name")
   read -r max mean <<<"$(convert "$OUT/$name.godot.png" "$OUT/$name.ref.png" \
     -compose difference -composite -format "%[fx:maxima*255] %[fx:mean*255]" info:)"
 
+  # HOW MANY pixels are over the bar, not just how far the worst one is. A
+  # single `max` cannot tell 2 pixels from 25 444, and this run produced both:
+  # `main_menu` trips the threshold on TWO pixels out of 921 600 while
+  # `title_jp` trips it on 2.8 % of the frame. Reporting only the max made those
+  # the same verdict, which is how a real disagreement hides behind a rounding
+  # one. The bar itself is NOT raised -- tuning a threshold until things match
+  # is the failure this script's own header warns about.
+  over=$(convert "$OUT/$name.godot.png" "$OUT/$name.ref.png" \
+    -compose difference -composite -colorspace Gray -threshold $((3*65535/255)) \
+    -format "%[fx:int(mean*w*h)]" info:)
+
   # 3/255 is what integer-truncating compositing in the CLI and float rounding
   # in a GPU differ by. Anything above that is a placement, order or colour
   # disagreement and needs a reason, not a threshold.
   verdict=OK
   awk "BEGIN{exit !($max > 3)}" && { verdict=DIFFERS; status=1; }
-  printf '%-16s build %-3s max %-5s mean %-8s %s\n' "$name" "$build" "$max" "${mean:0:6}" "$verdict"
+  printf '%-17s build %-3s max %-5s mean %-8s over3 %-7s %s\n' \
+    "$name" "$build" "$max" "${mean:0:6}" "$over" "$verdict"
 done
 echo "artifacts in $OUT"
 exit $status