e6f921d442
Answers question 1 of the 2026-09-02 play-test: interpolate or hold. It interpolates, piecewise-linearly, evaluated once per present at one unit per present. palogo_sqex_eff gives 28 distinct alphas over 28 consecutive presents, changing on 26 of 27 adjacent pairs. It is not one slope, and the disc says why: that element declares 0:a=0 -> 15:a=255 -> 30:a=212 -> 45:a=0, three segments with three gradients. Predicted -2.87 and -14.13 per unit against measured modal steps of -3 (x6) and -14 (x9). The declared keyframes predict the per-frame steps, which makes this a prediction rather than a description. So the port must lerp: hold-to-next-key would emit 3 states where the game emits 28. And "eased" is the wrong description -- there is no easing function, the envelope only looks eased because consecutive declared segments have different gradients. Alpha lives in the per-vertex k_8_8_8_8 colour, rewritten into a fresh vertex buffer every frame. Not a PS constant (ps_c[n=0] on 1048/1048), not a blend factor, not a texture swap. 🔴 And the game's splash is ALSO mostly frozen. Measured with the same statistic the play-test used on the port: the game moves 21.2% and 27.8% against the port's 16.4%, and its longest frozen run is 3.34 s against the port's 3.20 s. The publisher declares 205 of 255 units -- 80% -- as a flat hold at full opacity. That refutes the play-test's second clause. "A fade does not hold one picture for 3.20 s" -- this one does, for 3.34 s. Its first clause stands: 26 states for a 45-unit build-in is too few, the game gives 49 and 51. The deficit is the state count, not the freeze: ~100 against 26. Acting on the second clause would have sent the port to remove the one part of its splash that is already right. Not answered: which function does it. This is the behaviour; the image-side half of question 1 is still open. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01Jc4pciRArGHfxGGhEbwp5t
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-cliand 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
docs/re/INDEX.md— what is decodeddocs/re/REFUTED.md— what has been tested and dieddocs/re/METHOD.md— traps this project has already paid fordocs/game/navigation.md— how the game is navigateddocs/port/MODDING.md— why the asset tree looks the way it does
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.