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Mount SYS4 append asset catalogs

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gamer147
2026-07-11 10:42:33 -04:00
parent a1f6d0ab51
commit e0ca7936e2
9 changed files with 235 additions and 27 deletions
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docs/asset-resolution-re.md
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@@ -166,7 +166,7 @@ The current Phase-A backend deliberately continues through the extracted-file bo
accepts both OGG and WAV and Godot loads the WAV bytes into its fixed SC0000 channel pool. This does not change
the scoped VFS plan below: ALF/AAI mounting and in-process asset reads remain a separate foundation track.
## Runtime asset-VFS track (VFS-A and VFS-C complete 2026-07-11)
## Runtime asset-VFS track (VFS-A/B/C complete 2026-07-11)
The pre-extracted tree and `build/textures/*.BMP` pipeline were a Phase-A bootstrap, not the desired final
runtime. The native-compatible target is a read-only virtual filesystem that preserves AGE's translation/mod
@@ -194,11 +194,16 @@ store.
`call-script` targets through this seam; `ResourceMap` uses the same live catalog. `build/asset-index.json`,
`build/asset-sections.json`, `build/callscript-names.json`, and `extracted/` are validation/temporary
graphics-audio artifacts, not script-runtime dependencies.
2. **AAI append mount.** Parse the installed `APPEND01.AAI` (`S4AC422`) and its paired `APPEND01.ALF` with
the same catalog abstractions. First prove whether Himegari joins append records by a separate pack/tag,
by name replacement, or by another table selected by the native high-byte-id path; do not invent mount
precedence. Validate every parsed append entry against `BinExtractALF.exe` output before exposing it to
the runtime.
2. **AAI append mount (VFS-B DONE).** `Sys4AssetCatalog` also parses the installed `APPEND01.AAI`
(`S4AC422`) and mounts its paired `APPEND01.ALF`. This is a separate selector-keyed catalog, not a
filename overlay: AGE scans `*.AAI`, reads the selector at AAI header offset `0x108`, and stores the
successfully loaded catalog in `mounted_aai[selector]`. A resource id with a nonzero high byte selects
that slot; its low 24 bits index only the selected append table. Installed `APPEND01` is selector 1.
Within that catalog the ordinary exact loose-record-name then ALF-range precedence still applies, so the
literal `$1$...` names are preserved. A later successfully enumerated AAI with the same selector replaces
the earlier pointer in the native loop; no base/append name replacement occurs. Native extracts the
selector with arithmetic `SAR 24`; the port rejects sign-bit selectors rather than guessing behavior for
ids that would index before AGE's mount table.
3. **AGF decoder (VFS-C DONE).** `Age.Engine/Sys4/AgfDecoder.cs` decodes an opened AGF payload directly
to a tightly packed, top-down width/height + RGBA8 surface. The MIT-licensed GARbro
`ArcFormats/Eushully/ImageAGF.cs` provides a compact reference: `ACGF` (or zero) signature, type 1/2,
@@ -246,8 +251,15 @@ Five installed assets spanning raw/compressed metadata and pixel/alpha combinati
800×300 with intermediate alpha values, and is inherited in surface slot 17 before SC0000. A windowed
page-1 capture with `build/textures/` moved aside showed the translucent textbox edge and bottom-right
controls. Texture runtime no longer consults `extracted/` or `build/textures/`; current audio consumers
still use extracted OGG/WAV paths by design. APPEND01/AAI, audio migration, and movie `0x236` remain
unimplemented by this slice.
still use extracted OGG/WAV paths by design. Audio migration and movie `0x236` remain unimplemented.
VFS-B passes its bounded gates in `Sys4AssetStoreTests`: the installed AAI expands from the LZSS stream at
`0x118` (expanded size at `0x110`, packed size at `0x114`) to one `APPEND01.ALF` archive and 81 80-byte
records. All records carry selector 1 and literal `$1$` names. The full directory has stable SHA-256
`23F0C104A45C099CEFB7D333362716EDE6F20B9EC53E4C3705A8E3A87063708E` over its ordered record fields.
The integration gate runs `BinExtractALF.exe` into a disposable directory, compares all 81 names, validates
every range and size, and byte-compares all 81 payloads. `Sys4ScriptProvider` resolves a real append script
through `0x01xxxxxx`; direct base-name lookup deliberately does not see append records.
### Deliberate non-goals