MOGP is a group file's last top-level chunk, so EOF is its real end. The walk
trusted the declared size instead, and `parse_group` answers an empty group for
a payload shorter than the 0x44 header — so a group that declares less than it
holds left MOVT/MOVI/MOPY sitting as top-level siblings *after* the payload and
parsed to no vertices, no indices and no batches. A building that draws nothing,
with no error anywhere to say why.
Seven files in this realm's chain do it, and all seven are the winning copy
(`patch-3.mpq`):
* the six `World\wmo\Outland\Shadowmoon\Slagpit\Shadowmoon_Slagpit01_00{0..5}
.wmo` declare 0x40, four bytes short of the header, over 33 KiB to 546 KiB
of geometry;
* `HumanHouse\WestfallHouse_MediumStraw_000.wmo` declares 0, over 41 KiB.
Measured before and after over the whole corpus: 7 of 7,795 group files parsed
to an empty group, now 0.
`wmo_chunk_overrun.rs` already covered the other direction — Undercity_144
declares one byte *past* EOF — but it only asks for the MOGP header, which
`find_wmo_chunk` clamps and which survives a short declaration too (0x40 still
carries flags, the portal refs and groupLiquid). The geometry is what was lost,
so the new corpus test asks for that: no group file of 1 KiB or more may parse
to zero vertices.
Ported from benilla-bourbon (tripleslash/benilla-bourbon, "a WMO group's MOGP
runs to EOF", credited there to kalistoking), whose `mogp_payload` and unit test
are taken unchanged; the Westfall house and the corpus test are this chain's.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01SgstFWtn1RxEJ5kVrpgYwn
gromandClaude Opus 5
d95f26e57f