sylph-decoder 441135f552 re: at least two thirds of the title s disagreement is geometry, not tone
Separates two confounded effects so the pending rotation decision has a number:
how much would drawing the rotation actually buy.

A per-level lookup table fitted on a screen is the most general tone model there
is -- every render level mapped to whatever capture level minimises the error,
no functional form assumed -- so whatever such a LUT cannot close is by
construction not a per-level effect. Fitting on the screen itself therefore gives
an upper bound on the tone share and a lower bound on the geometry share.

Positive control: on the main menu, where the port measures 0.06 percent of
pixels differing so geometry is essentially right, a self-fitted LUT closes
70.3 percent, from 9.26 to 2.75. The instrument can collapse a tone-dominated
residual.

Result: on the title the same self-fitted LUT closes only 32.0 percent, from
10.92 to 7.42. So at most a third of the title s disagreement is tone and at
least two thirds is spatial -- content in the wrong place, which is where the
rotation lives. The fitted LUT is generous to tone, so the geometry share is if
anything larger.

Also refutes the idea of a single transferable tone curve. Fitted on the title
and applied to the menu it closes 29.7 percent; fitted on the menu and applied to
the title it makes things 24 percent WORSE. A curve fitted on a dark flat screen
is unconstrained at the bright end -- the menu s populated range is levels 5 to
204 with few bright pixels -- and extrapolating it onto the title s planet and
wordmark actively harms. That extends the existing refutation of the single
exponent: even a full per-level LUT fails to transfer, so a consumer must not
carry a global tone correction.

Reach: two screens, one capture each, and the title pairing is the same screen
but not the same instant, so the ratio is what is claimed rather than the
absolute level. Our render draws the sweeps parent record only, so the geometry
share includes both the missing rotation and the missing leaf placement -- both
closed by the same decision.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01QsEPXWVaEpyfudtR6re1Pd
2026-08-29 18:45:15 +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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