Files
Syplheed-Reborn/crates/sylpheed-formats/tests/mesh_disc.rs
Claude (auto-RE) 41b59faf5f fix(xbg7): the index run was one element late for 575 sub-meshes
Extending the capture comparison from index COUNTS to index VALUES
(`examples/capture_index_bytes.rs`, using the batch offsets the new ib logging
gives) showed 76 of 93 Stage_S02 index runs identical to the GPU's and 17
differing — every difference a shift by exactly one element, on buffers whose
index data sits at pad 2.

`anchor_pool_mesh` returned the FIRST pad that validated, and pad 0 is tried
first with the looser winding gate (0.70 vs 0.85). Read at pad 0, a pad-2 block
yields [true[1], true[2], …, garbage]: every index in range, the pool covered,
the positions right, the winding often just above 0.70 — so it validated, and
every triangle was mis-wired. Nothing count-based could see it.

The signature is decidable without the capture: a shifted run wires arbitrary
vertices, so triangles come out degenerate. 282 of 283 correctly anchored
Stage_S02 blocks have zero degenerate triangles, while the shifted readings carry
1–2 156. So score every validating pad by (degenerate triangles, then winding)
and keep the best. `XBG7_PAD_FIRST_MATCH=1` restores the old behaviour.

  captured index runs identical:            76/93  ->  93/93  (2 025 elements)
  decoded runs with a degenerate triangle:    579  ->     16  (disc-wide)
  sub-meshes whose index run changed:                    575  of 8 850
  resources decoded / vertex anchors / consistency:  unchanged (6 209 / same vb / 89)

Locked in by tests/mesh_disc.rs::decoded_index_runs_have_almost_no_degenerate_triangles.
Suite green with --include-ignored apart from the pre-existing known-failing
cross-container consistency test (the 24-vertex bounding-box class).

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NptfmpjdpNCKEez6d2xvA9
2026-08-13 07:26:52 +00:00

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//! Integration test: decode XBG7 geometry from REAL `.xpr` model files.
//!
//! Uses loose files extracted from the retail disc (models live in
//! `hidden/resource3d/*.xpr`). Skipped unless the directory is found; point
//! `SYLPHEED_RES3D` at it to override.
//!
//! Run: `cargo test -p sylpheed-formats --test mesh_disc -- --ignored --nocapture`
use std::path::PathBuf;
use sylpheed_formats::mesh::{material_groups, node_transforms, submesh_albedos, Xbg7Model};
fn res3d_dir() -> Option<PathBuf> {
if let Ok(p) = std::env::var("SYLPHEED_RES3D") {
let p = PathBuf::from(p);
if p.is_dir() {
return Some(p);
}
}
let default =
PathBuf::from("/home/fabi/RE - Project Sylpheed/sylph_extract/hidden/resource3d");
default.is_dir().then_some(default)
}
#[test]
#[ignore = "requires extracted disc models — set SYLPHEED_RES3D"]
fn hero_ship_submesh_material_graph() {
let Some(dir) = res3d_dir() else {
eprintln!("SKIP: resource3d dir not found (set SYLPHEED_RES3D)");
return;
};
// The XBG7 node/material graph tags each sub-mesh record with its own albedo
// (`rou_…_col` → TX2D name). DeltaSaber_T `f001`: the 7 detail parts use
// bdy_04/06/07 — NOT the body's bdy_01a — which is the per-part texturing the
// viewer needs so fins aren't painted with the hull map.
let bytes = std::fs::read(dir.join("DeltaSaber_T.xpr")).unwrap();
let mut map = std::collections::HashMap::new();
for (v, i, name) in submesh_albedos(&bytes, "f001") {
map.insert((v, i), name);
}
// (vtx, idx) → expected albedo (rou_ stripped = TX2D name).
assert_eq!(map.get(&(314, 645)).map(String::as_str), Some("f001_bdy_04_col"));
assert_eq!(map.get(&(48, 84)).map(String::as_str), Some("f001_bdy_04_col"));
assert_eq!(map.get(&(96, 180)).map(String::as_str), Some("f001_bdy_06_col"));
assert_eq!(map.get(&(60, 108)).map(String::as_str), Some("f001_bdy_07_col"));
// Names strip cleanly to real TX2D resources.
let tex = sylpheed_formats::texture::X360Texture::texture_names(&bytes);
for name in map.values() {
assert!(tex.iter().any(|t| t == name), "albedo {name} not a TX2D resource");
}
}
#[test]
#[ignore = "requires extracted disc models — set SYLPHEED_RES3D"]
fn hero_ship_body_splits_by_material() {
let Some(dir) = res3d_dir() else {
eprintln!("SKIP: resource3d dir not found (set SYLPHEED_RES3D)");
return;
};
// The merged body (sub0 = 24561 indices / 8187 tris) is drawn as 9 groups
// sharing one index buffer, each with its own albedo (bdy_01a hull, bdy_01b,
// bdy_02/03, and the `daiza` hangar stand). `material_groups` recovers the
// cumulative-offset chain so the viewer can texture each slice.
let bytes = std::fs::read(dir.join("DeltaSaber_T.xpr")).unwrap();
let groups = material_groups(&bytes, "f001", 24561);
assert_eq!(groups.len(), 9, "body must split into 9 material groups");
// Offsets chain from 0 and cover the whole index buffer exactly.
let mut cursor = 0usize;
for g in &groups {
assert_eq!(g.idx_offset, cursor, "group offsets must be contiguous");
cursor += g.idx_count;
}
assert_eq!(cursor, 24561, "groups must cover all body indices");
// Expected per-group albedo (verified against the GPU draw log).
let albedos: Vec<&str> = groups.iter().map(|g| g.albedo.as_str()).collect();
assert_eq!(
albedos,
[
"f001_bdy_01a_col",
"f001_bdy_01a_col",
"f001_bdy_01a_col",
"f001_bdy_01b_col",
"f001_bdy_01a_col",
"f001_bdy_01b_col",
"f001_bdy_02_col",
"f001_bdy_03_col",
"f001_bdy_daiza_col",
]
);
// A single-material detail part (sub1 = 645 indices) → one group, bdy_04.
let fin = material_groups(&bytes, "f001", 645);
assert_eq!(fin.len(), 1);
assert_eq!(fin[0].albedo, "f001_bdy_04_col");
assert_eq!(fin[0].idx_offset, 0);
}
#[test]
#[ignore = "requires extracted disc models — set SYLPHEED_RES3D"]
fn hero_ship_node_transforms_move_fins_to_tail() {
let Some(dir) = res3d_dir() else {
eprintln!("SKIP: resource3d dir not found (set SYLPHEED_RES3D)");
return;
};
// For the DeltaSaber, node_transforms returns the MEASURED runtime placements
// (Canary draw-log WVP; see mesh.rs::DELTASABER_MEASURED) — the fin assemblies
// are mounted OUT on the nacelles (world X ≈ 4.4..6.6), an offset the static
// graph omits. Body identity; each part a left/right mirrored pair. Vertex
// space: X right, Y up, Z fore/aft (engines at Z).
let bytes = std::fs::read(dir.join("DeltaSaber_T.xpr")).unwrap();
let places = node_transforms(&bytes, "f001");
assert!(!places.is_empty(), "expected node placements");
// Body (sub 0) identity, drawn once.
let body: Vec<_> = places.iter().filter(|p| p.sub_index == 0).collect();
assert_eq!(body.len(), 1, "body drawn once");
assert!(body[0].t.iter().all(|c| c.abs() < 0.1), "body must not translate");
assert!(!body[0].reflect, "body is not mirrored");
// Fin bdy_04 (sub 1): mirrored pair near the tail, mounted OUT on the nacelle
// (|X| ≈ 5.2, not the graph's inboard ≈1.1).
let fins: Vec<_> = places.iter().filter(|p| p.sub_index == 1).collect();
assert_eq!(fins.len(), 2, "V-tail is a mirrored pair");
assert!(fins.iter().all(|f| (f.t[2] + 9.72).abs() < 0.3), "fin fore/aft ≈ 9.7");
assert!(fins.iter().all(|f| f.t[0].abs() > 4.0), "fin mounted out on the nacelle");
assert!(fins[0].t[0] * fins[1].t[0] < 0.0, "the pair mirrors across X");
assert!(fins.iter().any(|f| f.reflect), "one of the pair is reflected");
// Winglet bdy_06 (sub 4): on the nacelle (|X| ≈ 6.6, Z ≈ 15.5).
let wings: Vec<_> = places.iter().filter(|p| p.sub_index == 4).collect();
assert_eq!(wings.len(), 2, "L/R winglet pair");
assert!(wings.iter().all(|p| p.t[0].abs() > 6.0 && (p.t[2] + 15.5).abs() < 0.3),
"winglets out on the nacelle");
assert!(wings[0].t[0] * wings[1].t[0] < 0.0, "winglets mirror across X");
// Small fin bdy_10 (sub 6): inboard nacelle stub (|X| ≈ 4.45, Z ≈ 17).
let sfins: Vec<_> = places.iter().filter(|p| p.sub_index == 6).collect();
assert_eq!(sfins.len(), 2, "L/R small-fin pair");
assert!(sfins.iter().all(|p| (p.t[0].abs() - 4.45).abs() < 0.3), "small fins on the stub");
assert!(sfins[0].t[0] * sfins[1].t[0] < 0.0, "small fins mirror across X");
}
#[test]
#[ignore = "requires extracted disc models — set SYLPHEED_RES3D"]
fn weapon_model_decodes_to_expected_geometry() {
let Some(dir) = res3d_dir() else {
eprintln!("SKIP: resource3d dir not found (set SYLPHEED_RES3D)");
return;
};
// rou_f001_wep_00 = the player ship's first weapon: 1 sub-mesh,
// 215 vertices, 364 triangles (verified by hex analysis).
let bytes = std::fs::read(dir.join("rou_f001_wep_00.xpr")).unwrap();
let model = Xbg7Model::from_xpr2(&bytes).expect("weapon must decode");
assert_eq!(model.meshes.len(), 1);
let (v, t) = model.totals();
assert_eq!(v, 215, "vertex count");
assert_eq!(t, 364, "triangle count");
let m = &model.meshes[0];
assert_eq!(m.positions.len(), 215);
assert_eq!(m.uvs.len(), 215);
assert_eq!(m.normals.len(), 215);
assert_eq!(m.indices.len(), 1092);
// every index in range
assert!(m.indices.iter().all(|&i| (i as usize) < m.positions.len()));
// positions are real geometry within the model's ~2-unit bbox
let ys: Vec<f32> = m.positions.iter().map(|p| p[1]).collect();
let span = ys.iter().cloned().fold(f32::MIN, f32::max)
- ys.iter().cloned().fold(f32::MAX, f32::min);
assert!(span > 1.0 && span < 10.0, "y-span {span} out of range");
// Correct vertex alignment ⇒ normals are unit-length (the pin for the
// +12 vertex offset) and UVs land in a sane texture range.
let mean_nlen: f32 = m
.normals
.iter()
.map(|n| (n[0] * n[0] + n[1] * n[1] + n[2] * n[2]).sqrt())
.sum::<f32>()
/ m.normals.len() as f32;
assert!((mean_nlen - 1.0).abs() < 0.05, "mean |normal| {mean_nlen} ≠ 1");
assert!(
m.uvs.iter().all(|uv| uv[0] > -0.1 && uv[0] < 2.0 && uv[1] > -0.1 && uv[1] < 2.0),
"UVs out of expected [0,1]-ish range"
);
}
#[test]
#[ignore = "requires extracted disc models — set SYLPHEED_RES3D"]
fn declaration_driven_decode_covers_expected_model_count() {
let Some(dir) = res3d_dir() else {
return;
};
let mut ok = 0usize;
let mut total = 0usize;
for entry in std::fs::read_dir(&dir).unwrap() {
let path = entry.unwrap().path();
if path.extension().and_then(|e| e.to_str()) != Some("xpr") {
continue;
}
total += 1;
let bytes = std::fs::read(&path).unwrap();
if let Ok(model) = Xbg7Model::from_xpr2(&bytes) {
if !model.meshes.is_empty() {
// Every decoded model must be self-consistent (indices in range,
// and unit normals where present).
for m in &model.meshes {
assert!(
m.indices.iter().all(|&i| (i as usize) < m.positions.len()),
"{path:?}: index out of range"
);
}
ok += 1;
}
}
}
eprintln!("XBG7 declaration-driven decode: {ok}/{total} models");
// Variable-stride declaration parsing lifted coverage vs the old fixed
// stride-24 decoder (25 → 36 fully-validated models; multi-sub-mesh models
// whose later sub-mesh offset isn't yet handled are still declined whole).
assert!(ok >= 35, "coverage regressed: only {ok}/{total} decoded");
}
#[test]
#[ignore = "requires extracted disc models — set SYLPHEED_RES3D"]
fn complex_body_mesh_is_declined_not_garbage() {
let Some(dir) = res3d_dir() else {
return;
};
// The hero-ship body uses the multi-stream layout we do not decode; it must
// be cleanly rejected, never returned as partial geometry.
let bytes = std::fs::read(dir.join("DeltaSaber_A.xpr")).unwrap();
match Xbg7Model::from_xpr2(&bytes) {
Err(_) => {} // expected: declined
Ok(m) => {
// If it ever does decode, it must at least be self-consistent.
for mesh in &m.meshes {
assert!(mesh.indices.iter().all(|&i| (i as usize) < mesh.positions.len()));
}
}
}
}
/// The hero ship's **grouped-pool** layout decodes fully: `DeltaSaber_T.xpr`'s
/// `f001` resource is one vertex+index pool shared by 8 sub-meshes (body + 7
/// detail parts). Reversed statically and cross-checked against a Canary GPU
/// draw-log capture — every sub-mesh's stored normals agree with its triangle
/// winding (0 degenerate, full vertex coverage). This is the layout the old
/// per-block adjacency anchor rendered as a spiky phantom.
#[test]
#[ignore = "requires extracted disc models — set SYLPHEED_RES3D"]
fn hero_ship_grouped_pool_decodes() {
let Some(dir) = res3d_dir() else {
eprintln!("SKIP: resource3d dir not found (set SYLPHEED_RES3D)");
return;
};
let bytes = std::fs::read(dir.join("DeltaSaber_T.xpr")).unwrap();
let models = Xbg7Model::stage_models(&bytes);
// The neutral pose `f001` (the mnv*/turn180 resources are animation poses).
let f001 = models.iter().find(|m| m.name == "f001").expect("f001 decoded");
assert_eq!(f001.meshes.len(), 8, "body + 7 detail sub-meshes");
let (v, t) = f001.totals();
assert_eq!(v, 11607, "vertex total across sub-meshes");
assert_eq!(t, 8650, "triangle total (body 8187 + 7 parts)");
// Sub-mesh 0 is the body: exactly the draw-log-verified geometry.
let body = &f001.meshes[0];
assert_eq!(body.positions.len(), 10891);
assert_eq!(body.indices.len(), 24561);
for (i, m) in f001.meshes.iter().enumerate() {
// Every index in range.
assert!(
m.indices.iter().all(|&ix| (ix as usize) < m.positions.len()),
"sub{i}: index out of range"
);
// Correct alignment ⇒ unit normals, and the winding agrees with them
// (the decisive correctness signal, ~1.0, not the ~0.5 of a mis-carve).
let n = m.normals.len();
assert_eq!(n, m.positions.len(), "sub{i}: a normal per vertex");
let mean_nlen: f32 = m
.normals
.iter()
.map(|nv| (nv[0] * nv[0] + nv[1] * nv[1] + nv[2] * nv[2]).sqrt())
.sum::<f32>()
/ n as f32;
assert!((mean_nlen - 1.0).abs() < 0.05, "sub{i}: mean |normal| {mean_nlen} ≠ 1");
let mut agree = 0usize;
let mut counted = 0usize;
for tri in m.indices.chunks_exact(3) {
let (a, b, c) = (tri[0] as usize, tri[1] as usize, tri[2] as usize);
let (pa, pb, pc) = (m.positions[a], m.positions[b], m.positions[c]);
let u = [pb[0] - pa[0], pb[1] - pa[1], pb[2] - pa[2]];
let w = [pc[0] - pa[0], pc[1] - pa[1], pc[2] - pa[2]];
let f = [
u[1] * w[2] - u[2] * w[1],
u[2] * w[0] - u[0] * w[2],
u[0] * w[1] - u[1] * w[0],
];
if f[0] * f[0] + f[1] * f[1] + f[2] * f[2] < 1e-12 {
continue;
}
let sn = [
m.normals[a][0] + m.normals[b][0] + m.normals[c][0],
m.normals[a][1] + m.normals[b][1] + m.normals[c][1],
m.normals[a][2] + m.normals[b][2] + m.normals[c][2],
];
if f[0] * sn[0] + f[1] * sn[1] + f[2] * sn[2] > 0.0 {
agree += 1;
}
counted += 1;
}
let na = agree as f32 / counted.max(1) as f32;
assert!(
na.max(1.0 - na) > 0.95,
"sub{i}: winding-vs-normal agreement {na} — mis-carved (should be ~1.0 or ~0.0)"
);
}
}
/// Stage containers decode multiple enemy/prop sub-models via content anchoring.
/// Prints coverage; asserts the known-good Stage_S10 meshes decode with sane geometry.
#[test]
#[ignore]
fn stage_models_decode() {
use sylpheed_formats::mesh::Xbg7Model;
let dir = std::env::var("SYLPHEED_RES3D").unwrap_or_else(|_| {
"/home/fabi/RE - Project Sylpheed/sylph_extract/hidden/resource3d".to_string()
});
let path = format!("{dir}/Stage_S10.xpr");
let bytes = std::fs::read(&path).expect("read Stage_S10");
let models = Xbg7Model::stage_models(&bytes);
for m in &models {
let (v, t) = m.totals();
let mut lo = [f32::MAX; 3];
let mut hi = [f32::MIN; 3];
for sub in &m.meshes {
for p in &sub.positions {
for a in 0..3 {
lo[a] = lo[a].min(p[a]);
hi[a] = hi[a].max(p[a]);
}
}
}
let ext = [hi[0] - lo[0], hi[1] - lo[1], hi[2] - lo[2]];
println!(
" {:16} v={v} t={t} bbox=[{:.1},{:.1},{:.1}]",
m.name, ext[0], ext[1], ext[2]
);
}
// Known: e003 (main enemy, ~1400 tris) must be among the decoded models.
let e003 = models.iter().find(|m| m.name == "e003").expect("e003 decoded");
let (v, t) = e003.totals();
assert_eq!(v, 2383, "e003 vertex count");
assert!(t > 1400, "e003 triangle count {t}");
assert!(models.len() >= 3, "at least 3 stage sub-models, got {}", models.len());
}
/// Timing/coverage sweep across all stage containers (manual; release recommended).
#[test]
#[ignore]
fn stage_models_sweep() {
use sylpheed_formats::mesh::Xbg7Model;
use std::time::Instant;
let dir = std::env::var("SYLPHEED_RES3D").unwrap_or_else(|_| {
"/home/fabi/RE - Project Sylpheed/sylph_extract/hidden/resource3d".to_string()
});
let mut names: Vec<_> = std::fs::read_dir(&dir)
.unwrap()
.filter_map(|e| e.ok().map(|e| e.file_name().into_string().unwrap()))
.filter(|n| n.starts_with("Stage_") && n.ends_with(".xpr"))
.collect();
names.sort();
let mut tot = 0usize;
for n in &names {
let bytes = std::fs::read(format!("{dir}/{n}")).unwrap();
let t0 = Instant::now();
let models = Xbg7Model::stage_models(&bytes);
let dt = t0.elapsed().as_millis();
tot += models.len();
println!("{n:16} {:>4} MB {:>3} models {:>5} ms", bytes.len()/1_000_000, models.len(), dt);
}
println!("TOTAL stage sub-models decoded: {tot}");
}
/// Quality audit: for a big stage, verify decoded models are real geometry
/// (bounded bbox, low full-mesh degeneracy) rather than false anchors.
#[test]
#[ignore]
fn stage_models_quality_audit() {
use sylpheed_formats::mesh::Xbg7Model;
let dir = std::env::var("SYLPHEED_RES3D").unwrap_or_else(|_| {
"/home/fabi/RE - Project Sylpheed/sylph_extract/hidden/resource3d".to_string()
});
let bytes = std::fs::read(format!("{dir}/Stage_S07.xpr")).unwrap();
let models = Xbg7Model::stage_models(&bytes);
let (mut small, mut mid, mut huge, mut dupnames) = (0, 0, 0, 0);
let mut seen = std::collections::HashSet::new();
let mut worst_deg = 0.0f32;
for m in &models {
if !seen.insert(m.name.clone()) { dupnames += 1; }
let mut lo = [f32::MAX; 3]; let mut hi = [f32::MIN; 3];
let mut deg = 0usize; let mut tot = 0usize;
for sub in &m.meshes {
for p in &sub.positions { for a in 0..3 { lo[a]=lo[a].min(p[a]); hi[a]=hi[a].max(p[a]); } }
for tri in sub.indices.chunks_exact(3) {
let (a,b,c)=(tri[0] as usize,tri[1] as usize,tri[2] as usize);
if a>=sub.positions.len()||b>=sub.positions.len()||c>=sub.positions.len(){continue;}
let pa=sub.positions[a]; let pb=sub.positions[b]; let pc=sub.positions[c];
let u=[pb[0]-pa[0],pb[1]-pa[1],pb[2]-pa[2]];
let v=[pc[0]-pa[0],pc[1]-pa[1],pc[2]-pa[2]];
let cx=[u[1]*v[2]-u[2]*v[1],u[2]*v[0]-u[0]*v[2],u[0]*v[1]-u[1]*v[0]];
if 0.5*(cx[0]*cx[0]+cx[1]*cx[1]+cx[2]*cx[2]).sqrt()<1e-9 { deg+=1; }
tot+=1;
}
}
let ext = (hi[0]-lo[0]).max(hi[1]-lo[1]).max(hi[2]-lo[2]);
let df = if tot>0 { deg as f32/tot as f32 } else {1.0};
worst_deg = worst_deg.max(df);
if ext < 200.0 { small += 1; } else if ext < 5000.0 { mid += 1; } else { huge += 1; }
}
println!("S07: {} models | small(<200u)={} mid={} huge(>5k)={} | dup-names={} | worst full-mesh degeneracy={:.1}%",
models.len(), small, mid, huge, dupnames, worst_deg*100.0);
// Each XBG7 resource must anchor to a *distinct* block (no collisions), the
// bulk must be bounded-scale geometry, and none may be mostly-degenerate.
assert_eq!(dupnames, 0, "no two resources should anchor to the same block");
assert!(small + mid > models.len() * 9 / 10, "≥90% bounded-scale geometry");
assert!(huge < models.len() / 20, "few huge (skybox-plane) models");
assert!(worst_deg < 0.35, "no model should be mostly-degenerate");
}
/// A correctly located index run has **no degenerate triangles**. That is the
/// signature the 2026-08-13 pad-scoring fix keys on: an index list read one
/// element late still passes every count-based gate but wires arbitrary
/// vertices, which produces triangles with a repeated index. Before the fix
/// **579** decoded runs on the disc carried such triangles (and a runtime
/// capture confirmed 17 of 93 index batches disagreed with the GPU); after it,
/// 16 sub-meshes do — all in resources that are separately known-broken. Locking the
/// number in, because the defect is invisible to coverage and to the anchor
/// oracle: every count stays correct while the geometry is mis-wired.
#[test]
#[ignore = "requires extracted disc models — set SYLPHEED_RES3D"]
fn decoded_index_runs_have_almost_no_degenerate_triangles() {
let Some(dir) = res3d_dir() else {
eprintln!("SKIP: resource3d dir not found (set SYLPHEED_RES3D)");
return;
};
let mut files: Vec<PathBuf> = std::fs::read_dir(&dir)
.expect("resource3d/")
.flatten()
.map(|e| e.path())
.filter(|p| p.extension().and_then(|s| s.to_str()) == Some("xpr"))
.collect();
files.sort();
let mut offenders: Vec<(String, String, usize)> = Vec::new();
for f in &files {
let Ok(bytes) = std::fs::read(f) else { continue };
let where_ = f.file_name().unwrap().to_string_lossy().to_string();
for m in Xbg7Model::stage_models(&bytes) {
for sm in &m.meshes {
let d = sm
.indices
.chunks_exact(3)
.filter(|t| t[0] == t[1] || t[1] == t[2] || t[0] == t[2])
.count();
if d > 0 {
offenders.push((m.name.clone(), where_.clone(), d));
}
}
}
}
// The known 16 sub-meshes: the grouped `.dat` break composites in `ptc_pack`
// (`f102`/`f104`/`e107`, whose marker lists are documented not to map onto the
// stored blocks — 5 sub-meshes), plus `e201_bdy_03_m` (2 containers) and
// `_rou_f402_dead` (9). Every one has an independently recorded anchoring
// problem; a NEW name appearing here is a regression.
assert!(
offenders.len() <= 16,
"{} decoded index runs contain degenerate triangles (expected ≤ 16): {:?}",
offenders.len(),
&offenders[..offenders.len().min(20)]
);
}