Sylpheed/docs/port/MISSION.md

Primary objective — answer everything the menu port needs

Status: active, set 2026-08-28. This replaces "work the RE backlog" as the agent's primary objective. It does not change what the agent does — it is still reverse engineering — it changes what earns attention: an item is worth doing when the menu port is blocked on it.

Who builds what

You do not build the port. A separate agent will build it, from what you produce. Your deliverable is decoded, verified, written-down answers plus the reference data that proves them.

	container agent (you)	port agent
decodes the disc	✅	❌ — consumes your answers
measures the running game	✅	❌ — no emulator
writes docs/re/ and docs/port/HANDOFF.md	✅	reads them
Godot project, asset pipeline, transcoding	❌	✅

If you find yourself designing an export schema or writing GDScript, you have crossed the line. Stop and go back to the question you were answering.

crates/sylpheed-viewer is also not yours to change for this objective. The Explorer is the human's tool for exploring and verifying the RE work, it keeps its static-data-only rule, and the port does not depend on it.

The target

Someone else has to build this, from your answers alone:

developer logo splash  →  intro video  →  title / PRESS Ⓐ  →  main menu  →  submenus

No gameplay, no 3D, no HUD, no missions. If an answer is not needed to put those five screens on a display and let a person move through them with a d-pad and Ⓐ, it is not in this objective.

What is already answered

Do not re-derive these. They are in docs/re/ and the disc atlas:

• The screen archive. GP_TITLE.pak holds the whole title-side tree — build 4 the title with animating wordmarks, build 5 the five-button main menu, builds 6/8/9 submenus, and the developer splash as the palogo bundle in the same pak.
• Buttons are identifiable as data. Element kind 0x3002 is a button, 0x0 decoration, 0x10 a primitive; buttons sort top-to-bottom by resting Y; each pairs with an f-suffixed highlighted variant.
• The screen vocabulary. The GamePart id table, 29 entries at .rdata 0x820A1630, confirmed by the executable's own factory-registration strings.
• The resting pose rule — the hold, not the longest dwell — and that a keyframe is the start of a ramp.
• Screen composition, pixel-accurate for the tutorial pause menu and the title main menu, via sylpheed-cli screen render.
• The logo splash is not a video. logo1–logo4 are manifest-bound with no .wmv on the disc; the splash is the RATC screen, which already renders.

The open questions — these are the objective

Ordered by what blocks the port earliest. Each is done when its gate exists: a written docs/re/ result with the evidence, and reference data committed alongside it.

	Question	Gate
Q1	What is a keyframe time? Values run 16…269. 60 Hz frames would make the title intro ~4.5 s — plausible and untested. Also: is the ramp linear, or eased?	A measured answer against the running game, not an inference. Everything animated downstream depends on this number
Q2	Which build is which screen state? Confirm build↔state for splash, title/PRESS Ⓐ, main menu and each submenu	A table, each row confirmed against a capture of the real screen
Q3	Paint order for these six screens. Solved at runtime, unsolved from the file — the declaration table is provably not it	Either a rule derived from the bundle, or six measured orders and a clear statement that no file-side rule was found
Q4	What does each button do? Labels are baked into the sprites; no decoded field says which GamePart a button opens	Button → GamePart id, from code or from driving the game. Say which
Q5	Navigation semantics. Initial focus, wrap-around at the ends, whether left/right does anything, what B does on each screen	Observed behaviour, per screen
Q6	The boot sequence, and what drives it. Order is observable; the data or code that sequences it is not decoded. Include the attract loop and what returns to the title	The sequence, plus whatever the game reads to decide it
Q7	Transitions. What happens visually between screens — the pteff00.prm quads, a fade, a cut — and its timing	Described and timed against a capture
Q8	Menu audio. Which BGM per screen; which cue on move / confirm / back / error. The cue table is complete; the event binding is not	Cue names bound to events, with how you established each
Q9	Video binding. Which movie is the boot intro vs the new-game intro; whether playback is skippable and what ends it	Named movies plus the playback rules
Q10	What are a music bank's sub-waves? BGM_001.slb is three sub-waves — 10 KB, 4.47 MB, 4.67 MB — and we currently concatenate them blindly into one 347 s track. Two near-equal halves could be intro + loop, or two variations, or two halves of one piece. A menu that loops its music needs to know which	The role of each sub-wave, established for at least the menu BGM. "Concatenate" is a decision, not a default — right now it is a default nobody chose
S1	Ready Room probe. Gated — one iteration, then stop	A written go/no-go (see below)

Known unknowns — say so, do not fill them in

Some of these may turn out to be undecodable. That is a valid, useful answer, and it is better than a guess, because the port agent will otherwise have to author the mapping by hand and needs to know it is authoring rather than transcribing.

For each question, the answer is one of:

• decoded — here is the field, here is the disc-wide check;
• measured — not on the disc in any form we found, but here is what the running game does, and here is the capture;
• undecodable, with reach — we looked here, here and here, and this is why it is not there.

Never a fourth thing. In particular: if Q4 ends as "read the labels off the sprite images by eye", say exactly that — it is then an authored mapping on the port side, not a disc fact, and mislabelling it would put a guess into the port wearing the badge of a measurement.

The Ready Room probe (S1) — one iteration, then stop

GP_READY_ROOM.pak is the largest UI archive on the disc, 1 106 entries, and only 6 of its names resolve. It is also ISL-scripted. That is either a week or a quarter, and one cheap test tells you which.

Our screen catalog enumerates bundles by content, not by name — is_build / is_composable read the bytes — so unrecoverable paths do not necessarily mean unrenderable screens.

sylpheed-cli screen list "$SYLPHEED_DISC/dat/GP_READY_ROOM.pak"
sylpheed-cli screen render --build <n> "$SYLPHEED_DISC/dat/GP_READY_ROOM.pak" /tmp/rr.png

Report how many builds it finds, whether any composite looks like a Ready Room, and whether the room is 2D at all or 3D with a UI overlay — if it is 3D the answer is no-go by definition, not "try harder".

Then stop and write the go/no-go. Do not start Ready Room work on your own authority.

Handing it over

HANDOFF.md is the single page the port agent reads. Keep it current as you answer questions: it is a summary with links into docs/re/, not a second copy of the findings. An answer that is not reachable from HANDOFF.md has not been delivered.

Out of scope

3D, gameplay, HUD, missions, save/load, localisation beyond English, the Godot project itself, any asset pipeline, and any archive outside GP_TITLE, tables.pak, sound.pak and dat/movie/ — except for the S1 probe.