sylph-decoder e61c60029a re: the UI blend mode is MEASURED -- the frames are drawn ADDITIVE
Closes the one route t32-blend-mode-not-on-disc.md left open: the executable's
draw path. Canary's UI draw capture now logs RB_BLENDCONTROL0 per draw, and the
game was driven to the main menu and to EXTRAS with F10 at each.

The title-side UI uses two blend states and ONE pixel shader:

  0x07010701  src=ONE dst=1-SRC_ALPHA  alpha-over (premultiplied)
              ptbase, pteff05, the fade quad, ptmsg, ptmsg2, pttitle, buttons
  0x01010101  src=ONE dst=ONE          ADDITIVE
              ptframe1, ptframe2, ptframe3, pteff20, both rotated sweep strips

Two controls, both run before the result was read:

* the NDC->pixel conversion that identifies a draw by its quad size reproduces
  1134 and 1303 px for the two rotated sweep strips -- numbers measured by a
  different tool in a different session -- on BOTH screens. The tool prints
  PASS/FAIL and disclaims its own output on FAIL.
* pixel shader 0xE59B2B3DA4AA9008 is used with BOTH states, 12 draws additive
  and 18 alpha-over. ptframe1 and ptbase run the same shader; only the blend
  register differs. So this is a blend result, not a shader result.

This confirms the port's independent measurement -- it solved the composite per
pixel from two backgrounds and found additive halves alpha-over's error on both
frames -- by a route with nothing in common with it.

So the blend is no longer authored: 'any blend you choose is authored' was true
of the disc and is not true of the game. What is still unknown is which field
selects it; elements sharing a mode are batched into one draw call, so the
selection happens before the draw.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Wuu56cE8vJGTBtn1ppsk8v
2026-08-31 06:06:30 +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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