feat(a2b): asset-RE tooling + findings; render blocked on asset resolution
- tools/convert_agf.py (AGF->BMP stills), tools/frida/ (capture harness + README; Frida 17.15.3) - docs/asset-resolution-re.md: foundational RE steering doc (resId->file; graphics+audio; not machine-verifiable -> Frida ground truth + human oracle). RE plan: parse SYS4INI, crack resId->name, backend render (A2b plan Tasks 3-5), audio, movies. - Finding: SC0000 bg = slot-0 slideshow (res 0x23 first); resolution opaque (CGINIT not a name map, SYS4INI S4IC needs RE, Frida file-I/O noisy/memory-mapped, opening mixes MPEG movies). - slice plan updated; texture ops already engine-driven (Task 1, prior commit). Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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# Asset Resolution — foundational RE (graphics + audio)
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**The problem.** The bytecode loads assets by a small numeric **resource id** (`set-texture 0x23`,
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`play-voice N`, …). To render/play the *real* asset — driven by the bytecode, not hardcoded — the
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engine must resolve `resId → asset file`. This is **foundational** (nearly all visuals + all audio
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depend on it) and **not machine-verifiable** (no pixel/audio oracle), which makes it the largest,
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highest-risk area of the port. This doc is the steering state; it feeds the A2b render/audio slices.
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## What's already landed
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- **Graphics ops wired** (A2b-background, engine-driven): `create-texture 0x1f8` `(slot,w,h)`,
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`set-texture 0x1f9` `(resId,slot)`, `draw-texture 0x1fb` `(slot,x,y,w,h)` promoted from VM stubs to
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typed `IHost` methods; `CaptureHost` no-ops them (A1 trace-diff/A2a selftest stay green). The VM
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now *drives* graphics; only resolution + backend rendering remain.
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- **Audio ops named, not yet wired:** `play-voice 0xc4`, `play-bgm`.
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- **Tools:** `tools/convert_agf.py` (AGF→BMP for *stills* via `AGF2BMP2AGF.exe`); `tools/frida/`
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(runtime capture harness — see its README); Frida core installed (17.15.3).
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## Findings (2026-07-06)
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- **SC0000 background = a slot-0 full-screen slideshow.** The intro loads ~30 distinct full-screen
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images into slot 0 in order (`set-texture 0x23→0`, `0x25→0`, `0x27→0`, …), each drawn 800×600.
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Res `0x23` is the first. (There is also a persistent full-screen **slot 3** set *cross-context*,
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not in SC0000 — inherited from the parent/system scene.)
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- **The opening mixes movies + stills.** `AGF2BMP2AGF` reports `OP.AGF`/`MVB*.AGF` as
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"unsupported type (possibly MPEG)" → DATA5 `MVB*` (210) and `OP`/`ED` are **movies**, not stills.
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The opening's visible background did **not** match any `EV001*` still (confirmed by eye), so res
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`0x23`'s file is not obvious from the name space alone — resolution is required.
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- **Asset name spaces:** DATA2 = `EV*`/`EVM*` stills (985). DATA5 = `MVB*`/`OP`/`ED` movies (210).
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DATA3 = `.OGG` audio (`BGM*`, `ANA*` voice).
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- **The resolution chain is opaque statically.** `CGINIT` (`build/data/CGINIT.json`) is a
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925-column *numeric* record table (row-major, sparse) — **not** an id→filename map.
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**`SYS4INI.BIN` (magic `S4IC422`) is the authoritative asset index** the game + `BinExtractALF`
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use (name ↔ archive ↔ offset ↔ size), but filenames are **not stored as plain ASCII** (an
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`EV001AA` search misses), so it needs S4IC-format RE to parse.
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- **Frida file-I/O is noisy.** `ReadFile` hooks on `DATA2.ALF` capture reads during the opening, but
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the offsets/spans don't line up with extracted AGF sizes → the game likely **memory-maps** the
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archives (so `ReadFile` offsets are OS paging, not clean per-asset loads) and/or uses async reads.
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The robust hook is the game's **internal load-by-id function**, not file I/O.
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## The RE plan (ordered)
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1. **Parse `SYS4INI` (S4IC422) → an asset index** `{name, archive, offset, size}`. *Reusable and
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bounded* — it names every asset in every DATA*.ALF, gives archive-offset→name (to rescue Frida
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offsets), and is the **answer key** for step 2. Deliverable: `tools/parse_sys4ini.py` +
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`build/asset-index.json`. (Format reference: asmodean's `exs4alf`, which `BinExtractALF` is based on.)
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2. **Crack `resId → filename`.** With SYS4INI as the answer key, either (a) **order-correlate**: run
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SC0000 in our engine to get the `set-texture(resId)` sequence, capture the real game's asset-load
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order via a *reliable* Frida hook, and align them; or (b) **hook the internal load-by-id
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function** directly (find via the opcode dispatch for `0x1f9`) to read `resId → name` at the
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source. Likely underlying rule: `resId → CGINIT/table → name`. Deliverable: the mechanism +
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`vm-map/resources.json` (or a generated map) seeding at least SC0000's slideshow.
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3. **Wire the backend** (already designed — A2b-background plan Tasks 3–5): `ResourceMap` resolver +
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Godot `TextureRect` compositing; render only resolved full-screen slots. Mechanical once (1)+(2) land.
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4. **Audio** (parallel, same shape): resolve `play-voice`/`play-bgm` `id → OGG` via SYS4INI + a
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Frida audio capture (hook `DATA3.ALF` reads or the audio-play fn); play via Godot. Reuses the
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`tools/frida/` framework.
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5. **Movies** (`OP`/`MVB`, MPEG) — a separate video-playback path; deferred.
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## Validation reality (why this is the big haul)
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Unlike the VM/dialogue work (byte-exact trace oracle), graphics + audio have **no machine oracle**.
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Validation is: **Frida ground truth** (what the real game loads/plays for a scene) as the correctness
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anchor, plus **human eyeball/ear**. Treat every mapping as provisional until Frida-confirmed; the
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`resId→file` map is *data we curate against ground truth*, and the engine stays honest by only ever
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rendering what the executed bytecode + the map produce (never a hardcoded image).
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## Status
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A2b-background: **machinery landed** (texture ops engine-driven, tools, findings). The **render is
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blocked on asset resolution** (steps 1–2), which is promoted to its own foundational effort. Next:
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either start step 1 (`SYS4INI` parser) or bank momentum with the Frida-free **choices** sub-slice
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(static-RE opcode hunt) while resolution waits its scheduled turn.
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@@ -181,6 +181,17 @@ Toolchain: `godot --headless --path godot --import` → `dotnet build godot/Hime
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**Next = A2b:** background via `AGF2BMP2AGF.exe`, `play-voice`/`play-bgm`, choices → VM globals,
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just-enough `call-script`/state (unlocks richer scenes).
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### A2b-Background — machinery landed; render blocked on asset resolution (2026-07-06)
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Engine-driven texture ops shipped: `create/set/draw-texture` (0x1f8/0x1f9/0x1fb) promoted from VM stubs
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to typed `IHost` methods (CaptureHost no-ops → trace parity kept; engine tests 8/8). Tools: `convert_agf.py`
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(AGF→BMP stills) + `tools/frida/` capture harness (Frida 17.15.3 installed). **Blocked:** rendering the bg
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needs `resId → asset file` resolution, which proved opaque — CGINIT isn't a filename map, SYS4INI (S4IC422)
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needs format RE, Frida file-I/O offsets are noisy (memory-mapping), and the opening mixes movies (MVB/OP =
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MPEG) with stills so eyeball-curation stalled too. **Asset resolution promoted to a dedicated foundational
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RE effort** (graphics + audio; not machine-verifiable — Frida ground truth + human eye/ear are the oracle):
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see `docs/asset-resolution-re.md`. The backend render (ResourceMap + Godot compositing) stays designed in
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`docs/superpowers/plans/2026-07-06-a2b-background.md` Tasks 3–5, mechanical once resolution lands.
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---
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## Risks / open questions for A0
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