Sylpheed port agent f6fc269478 export: P0 — GP_TITLE's screens and sprites into the open tree
`sylpheed-export export` reads `dat/GP_TITLE.pak`, enumerates its twelve screen
builds, and writes each as one `sylpheed.screen/2` document with its sprite PNGs
beside it. `sylpheed-export check` validates that tree against docs/FORMAT.md
with no disc in hand — the P0 gate is "validates against FORMAT.md", which is
not something anyone can confirm by reading, so it is a program.

Two readings from FORMAT v1 turned out to be wrong and are corrected here rather
than carried:

* The focus sprite does NOT come from the element's `opt ` link. That was
  measured and refuted upstream, and this export shows why plainly: on the main
  menu `opt ` chains ptloop01 -> ptloop02 -> ptbtn01, two decorations and then a
  button. The highlight pairs by sprite NAME instead (ptbtn01.t32 <->
  ptbtn01f.t32), which is the convention HANDOFF blesses and which resolves all
  five main-menu buttons. The raw link is still exported, renamed `opt_link` so
  nothing downstream mistakes it for navigation.
* There are TWO modulate colours in different byte orders, and they multiply.
  v1's single `#rrggbbaa` could not carry both and silently dropped the alpha
  that every fade ramps. They are now `tint_rgba` and `fade_argb`, with the byte
  order in the key name, because getting it backwards is silent and reads as an
  art bug rather than a parse bug.

The exporter takes exactly one authored input: `authored/screen_names.json`,
because the disc does not name its builds and "build 5 is the main menu" is a
measurement (HANDOFF Q2), not a field. Every name it applies is stamped
`name_source: "authored"` with the evidence in `name_why`, and `check` rejects
an authored name that has no `why` — so the derived tree stays honest about
which of its fields is a decision.

Sprites are per screen, not a flat pool: `main_menu` and `extras` both ship a
`ptbase.t32` and they are different pictures.

Checked, not assumed:

* two exports of the same disc are byte-identical;
* five mutations of a valid main_menu.json — a broken paint_order permutation,
  a dangling focus_sprite, a reversed buttons list, a `#rrggbbaa` colour and an
  invented name_source — are each caught with a specific message.

`t` stays raw. Q1 is answered, but the seconds conversion is measured off the
running game and its own finding flags the frame-rate measurement as the part
worth re-testing; if the game presents at 60 Hz every duration halves. One
constant, at P2, in a file that says it is a decision.
2026-08-28 18:43:52 +00:00

Sylpheed Godot

A clean-room Godot 4 port of Project Sylpheed: Arc of Deception, starting with the menu shell: developer splash → intro video → title → main menu → submenus.

You need your own copy of the game. Nothing in this repository is game content. An offline exporter reads the disc you supply and writes an open, moddable asset tree; the Godot project reads only that tree and never touches a disc format.

  your disc  ──▶  crates/sylpheed-export  ──▶  export/   ──▶  port/  (Godot 4)
                  (Rust; decoders come from      JSON + PNG        reads ONLY
                   sylpheed-formats)             + OGG + OGV       open formats

Why the wall

Two reasons, and the second is the interesting one:

  1. Godot cannot read IPFB archives, RATC bundles, T8aD textures, XMA banks or WMV video, and it should not learn to.
  2. Modding is a goal of this port. If the runtime reads the original formats, modding means reverse engineering. If it reads JSON and PNG, modding means opening a file.

Where the knowledge comes from

The decoders live in sylpheed-formats, pinned by revision — a separate project, where the reverse engineering happens. Its docs/port/HANDOFF.md is the contract: what has been decoded, what was measured off the running game, and what is known to be undecodable. Read it before assuming a value is on the disc.

Layout

crates/sylpheed-export/ disc → open formats. Regenerates export/ wholesale
port/ the Godot 4 project
authored/ decisions that are not on the disc, each with its reason
export/ generated, gitignored, never hand-edited
docs/ the mission, the format spec, the agent's loop prompt

Status

Pre-P0. Nothing runs yet.

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