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port: localise the title disagreement; withdraw the question I filed for it

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Two iterations ago I filed title's 790-pixel gap with sylpheed-cli as needing the
Decoder's element list. That was a hypothesis dressed as a question and it is
refuted: the pixels sit at ptlogo_back2eff1 (pos 938,194) and BOTH renderers draw
it -- mean 95.60 against 95.08. A set difference would have confirmed nothing at
someone else's cost.

Also ruled out: a placement offset. Every +/-1 px roll is two orders of magnitude
worse (790 against >=175406).

The mechanism stays unknown and I am not guessing. My antialiasing test failed
its own control -- the edge mask covered 92% of the frame, so the 25.2% of
differing pixels on it is below chance.

Ask withdrawn rather than left standing: a row on a refuted premise is worse than
no row. The residual is 0.086% of one frame between two of our own renderers, on
a screen matching the oracle at 0.21%.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01N7FiFFFwbvG2uxdcEh8HyF
This commit is contained in:
Sylpheed port agent
2026-08-30 05:14:04 +00:00
parent fd6d9b6d47
commit 68b543e1a2
2 changed files with 59 additions and 5 deletions
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21
docs/port/BLOCKED.md
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@@ -605,7 +605,7 @@ and neither is measured against anything. It goes to whoever owns that call.
---
## `title` differs from `sylpheed-cli` on 790 pixels, and the leaf theory is refuted
## ~~`title` differs from `sylpheed-cli` on 790 pixels~~ — 🟢 localised by the port, ask withdrawn
*Derived from HANDOFF `9ca1eb5`. Raised 2026-08-30 by the port. Not urgent — the
port agrees with the **oracle** on this screen at 0.21 %, and that is the check
@@ -622,10 +622,21 @@ consistency harness compares against a renderer drawing no `.rat` leaves, so the
`loop_leaf_on_screens` changes the figures **not at all** — the harness poses at
`rest`, where the leaves do not draw.
What would help: **which elements `sylpheed-cli` draws on build 4 at `rest`**, as a
list. The port's own list is in any `--screen=title` log (`drew N: …`). A set
difference answers it immediately, and it is a question about our own tool rather
than about the game — no oracle run, no emulator.
🟢 **WITHDRAWN 2026-08-30 — the premise was refuted and the question was mine to
answer.** I asked for the CLI's element list on the theory that one renderer drew
something the other did not. It does not: the differing pixels sit at
`ptlogo_back2eff1` (`pos=[938, 194]`), and **both renderers draw it** — mean 95.60
in the port against 95.08 in the CLI. A set difference would have confirmed
nothing at somebody else's cost.
Also ruled out: a placement offset. Every ±1 px roll makes it two orders of
magnitude worse (790 against ≥ 175 406).
❔ The mechanism is still unknown, and I am not guessing at it: the antialiasing
test I tried failed its own control, with the edge mask covering 92 % of the frame.
See `DECISIONS.md`. **Nobody is asked for anything** — the residual is 0.086 % of
one frame between two of our own renderers, on a screen matching the oracle at
0.21 %.
⚠️ Do not read this as the port being wrong. Against the **capture**, `title` is at
0.21 % and `title_plate` at 0.00093 %. This is two of our renderers disagreeing,

43
docs/port/DECISIONS.md
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@@ -6402,3 +6402,46 @@ draw. Filed as open.
⚠️ `title_jp` is a localisation screen and out of scope (MISSION §7). `title` is on
the boot path and is not.
## The `title` disagreement, localised — and the question I filed for it was the wrong one
Two iterations ago I filed `title`'s 790-pixel disagreement with `sylpheed-cli` as
needing the Decoder: *"which elements does `sylpheed-cli` draw on build 4 at
rest"*. That was a hypothesis dressed as a question, and it is wrong. I could
answer it myself, and did.
### What is established
* **The pixels cluster in one place**: x ≈ 938–1162, y ≈ 172–310, as blobs of
20–66 px. That is `ptlogo_back2eff1`'s position, `pos=[938, 194]` — one of the
six `ptlogo_back2eff*` glows, all of which carry a sprite and **no declared
size**, so the texture supplies it.
* 🔴 **Both renderers draw it.** The region reads mean **95.60** in the port and
**95.08** in the CLI. So the premise of my filed question — that one draws an
element the other does not — is **refuted**. A set difference of element lists
would have answered nothing.
* **It is not a placement offset.** Rolling the port's frame by every combination
of ±1 px makes it *worse* by two orders of magnitude — 790 pixels aligned
against ≥ 175 406 for the best shift. The images are registered; they differ in
content on 0.086 % of the frame.
### What is not established, and why I am not guessing
The mechanism. My next hypothesis was edge antialiasing, and **the test failed its
own control**: the edge mask classified **92 % of the frame** as edge, so the
25.2 % of differing pixels landing on it is *below chance* and the instrument is
dead. A number from it would have been noise wearing a decimal point.
### The ask is downgraded rather than left standing
`BLOCKED.md`'s row asked for the wrong thing on a refuted premise, which is worse
than no row: it would have spent someone else's time confirming a difference that
is not there. Corrected.
⚠️ And the residual value is genuinely low. This is **two of our own renderers**
disagreeing on 0.086 % of one frame, on a screen where the port matches the
**oracle** at 0.21 % and its plate variant at 0.00093 %. `verify-screen`'s own
header says a DIFFERS means *"we moved apart, go find out which of us moved"* —
here neither moved from the game. It stays visible as a DIFFERS rather than being
allowed, because an allowance is how the two `title` rows hid inside "six
expected" in the first place.