sylph-decoder 5c70e5d545 re: the forced-backdrop rule's pixel cost -- 38 screens go black without it
Follows the necessity census. 'The order moves' is a property of the sort; the
tie-break work already found reorders costing zero pixels, so the picture
moving is a separate claim. Rendered each of the 62 deciding builds twice and
diffed.

  38 .prm deciders: changed_px == ink_px in ALL 38. Without the rule the
                    primitive sorts last, paints over everything, and the
                    screen composites to pure black. The port's original
                    contradiction argument, measured on 38 builds across seven
                    archives instead of argued on two.
  24 .tbm deciders: zero -- and that is MY INSTRUMENT, not a finding.

The control asked whether the composite had ink; it always does. The question
was whether the reordered ELEMENT has ink, and compose draws no pixels at all
for a .tbm. So those 24 zeros measure our renderer's blindness by construction.
tie_break_pixel_cost.rs already had the per-element ink_mask this needed.
Reported rather than quietly patched: a control that cannot fail is the shape
this corpus keeps paying for.

Also corrects two things the port agent caught:

  - 'Two renderers, same answer' was true of the six GP_TITLE instances and not
    of the other 74. The port's re-run of my probe is my code executed twice;
    its independent leg was removing its own exporter post-pass, which covers
    GP_TITLE only. The disc-wide 62 has one witness and the page now says so.
  - forced_backdrop_necessity.rs defaulted to GP_TITLE with no argument, so a
    bare run printed 6 instances in the same format as 80. It now walks every
    dat/*.pak and reports the archive count.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Wuu56cE8vJGTBtn1ppsk8v
2026-08-30 07:04:05 +00:00

Sylpheed

A clean-room reverse engineering and port project for Project Sylpheed: Arc of Deception (Xbox 360, 2007).

Three things live here, in one repository so that a change spanning them lands as one commit:

The decoders crates/sylpheed-formats — the disc's formats, read and verified disc-wide
The port port/ — a Godot 4 project, plus crates/sylpheed-export which converts a disc into the open asset tree it reads
The corpus docs/re/ — what has been reverse engineered, with its evidence, its retractions and its dead ends

You need your own copy of the game. No game content is in this repository and none ever will be. The exporter reads the disc you supply.

The oracle is the real game

sylpheed-cli and the Explorer are tools for verifying our decoding. They are hypotheses under test and they have been wrong. When something must be checked against the truth, the truth is the game running in Xenia Canary, captured — not any renderer of ours.

This is stated first because getting it backwards is the most expensive mistake this project has made.

Layout

crates/
  sylpheed-formats/   the decoders. Disc-wide verified; the corpus is its spec
  sylpheed-cli/       headless tools -- render a screen, dump a table, probe audio
  sylpheed-viewer/    the Explorer: a human's window onto the disc. STATIC data only
  sylpheed-export/    disc -> the open, moddable asset tree
port/                 the Godot 4 project. Reads open formats ONLY
authored/             decisions that are NOT on the disc, each with its reason
data/
  base/               generated by the exporter. Gitignored, never hand-edited
  mods/               drop-in overrides. Yours
docs/
  re/                 the corpus: findings, refutations, method traps
  game/               how the game is navigated -- menus, modals, flight
  port/               the port's mission, its handoff contract, modding rules
  agents/             how the agent team works together
tools/                capture harnesses, probes, the share tool
exchange/             transient inter-agent files. NOT in git
docker/               the agent containers

Where to start

Xenia Canary is a separate repository: it is a fork tracking upstream, and it carries our instrumentation.

Conventions

Confidence is per claim, never per document: CONFIRMED · 🟡 PROBABLE · HYPOTHESIS · REFUTED. A withdrawn result is kept with its reasoning rather than deleted — that is why the numbers here can be trusted.

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