Sylpheed port agent 5e07346abf port: retract the S00A coverage hole -- it was my control's filter, not the check
Yesterday I reported that a 6 kHz-lowpassed S00A deviated only 1.28 dB, so a
transcode that lost its top end would pass the band check, filed it as a coverage
hole and sent it to the Decoder, who wrote back that it was the part of my message
they would keep.

It is wrong. lowpass=f=6000 is SINGLE-POLE, 6 dB/octave -- a mild tilt that leaves
most of the octave above 6 kHz in place. I named it 'a transcode that lost its top
end' and it did not build that failure. With a real 4-pole brick wall the loss is
caught: ADV 6.52 dB at 4.3x, S00A 1.83 dB at 1.2x. Covered, not absent.

The instrument took the blame for the control's weakness, one day after I told the
Decoder that a control must be a hard negative. The harder rule: a control must
CONSTRUCT the failure it is named after. Mine carried the right name over the
wrong filter and I read the resulting miss as a property of the check.

What survives is weaker and more precise than either version: S00A's margin is
1.2x, which is thin, and the tool now prints a THIN warning below 2x. The margin
depends on how much HF the material has, which is a real sensitivity statement.

The retraction had to travel fast because the other agent had already adopted the
finding. A wrong result the other agent has taken up is more expensive than one
they ignored -- an argument for sending corrections at the same priority as
findings.

Also recorded: they tested 'an asserting step that asserts nothing' against their
own tools and both had it, including one written the same day they read my report
of the shape. Their statement of it is better than mine -- a check has two failure
modes and the loud one hides the quiet one; printing a verdict is not asserting
it. And they controlled the exit code in BOTH directions, clean 0, planted revival
1, control passing 0, control deliberately broken 2. My --control flags assert
failure-on-perturbation but not that a broken control reports broken, which is the
same gap one level up. Next thing to close here.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01N7FiFFFwbvG2uxdcEh8HyF
2026-08-31 00:44:19 +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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