port: the title residual is a horizontal redistribution, and three of my own explanations are dead

`title` is the port's largest disagreement with the oracle at 1.82%, and last
iteration I attributed it to the moving ptloop sweeps without checking. Wrong,
and so were the two hypotheses I formed after it.

NOT THE SWEEPS. ptloop01/02 are 399x180 at (441,270) -- small and central -- and
their exported keyframes hold pos, scale and rotation constant. The difference
peaks at x~1088.

NOT AN OVER-HELD ELEMENT. Added `--no-hold` to render the alternative: playing
the title's groups past rest fades the screen to black by t=5.2 s, 30.97%
differing against 1.82% held. Holding at rest is right.

NOT A TIMING OFFSET. Sweeping the build-in gives 24.05% at t=1.6 falling
monotonically to 1.68% at t=4.18 and 1.82% settled. The capture is at the settled
end.

WHAT IT IS: a horizontal redistribution. Signed difference by cell shows the port
DARKER centre-left (-13.1, -8.3, -6.6) and BRIGHTER right (+16.0, +9.9), nearly
cancelling -- whole-frame means 63.8 against 62.5. Brightness in the wrong place,
not a level error or a tone ramp. It falls in the rows spanned by the two wide
elements ptlogo_back2 (1118x262) and ptlogo_back2eff (1133x280), with the column
profile falling off past x~1152 against their right edges at 1189 and 1197.

AND THE EXPORT CARRIES NO BLEND MODE. ptlogo_back2eff's keys are declared, id,
index, keyframes, kind_raw, layer, layer_source, pivot, rest, role, sprite --
there is no blend field, in this element or in FORMAT.md at all, and the port
composites everything with normal alpha. If the game draws `_eff` layers
additively, a wide gradient sprite would produce exactly this signature and
nothing in the export would reveal it. Asked, not assumed; I have not tested it,
and I am recording it because the three I could test are dead.

Recorded and NOT acted on: pteff02's rest.t is 46, where its fade is 25% black,
while its own group reaches 0x00000000 at t=236 -- so the port holds a black veil
the timeline removes. Third instance of rest.t naming a hold that is not the
settled state. It does not explain the residual: removing a darkening veil would
make the port brighter still, and it is already brighter where it disagrees.

`--no-hold`'s first version set the flag thirty lines before `view` exists and
silently rendered nothing, caught because the loop found no files rather than
because anything reported an error.

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

port/scripts/boot.gd

@@ -182,6 +182,18 @@ func _ready() -> void:
 	# own logic on purpose -- see `looping_focus` there for the census that says
 	# this cannot be a rule.
 	_looping = timing.get("looping_focus_records", {})
+	# `--no-hold` plays a screen's groups PAST their rest instead of clamping each
+	# element at its own `rest.t`. A diagnostic, not a mode: `rest.t` is the last
+	# HOLD keyframe before the exit, not the settled state, and the only way to
+	# ask "is the port's held pose what the idle game shows" is to be able to
+	# render the other answer. Added when the title's 1.8 % disagreement with the
+	# oracle could not be attributed without it.
+	#
+	# It goes HERE and not with the other flags: `view` does not exist until this
+	# point, and the first version set it thirty lines too early and silently
+	# rendered nothing.
+	if args.has("no-hold"):
+		view.holding = false
 	viewport.add_child(view)
 
 	view.looping_focus = _looping_for(name)