[formats,viewer] Decode grouped-pool XBG7 models; fix mesh routing + albedo

Revert the mis-guided "triangle STRIP" reading (a937779): XBG7 index
buffers are triangle LISTS (prim=4 in the GPU capture; stored-normal
agreement 1.000 as a list vs ~0.49 as a strip). Reinstate the
winding-consistency gate.

Crack the grouped-pool layout used by the hero ship and ~150 detailed
models. A resource's sub-meshes share one index pool (buffers 4-byte
aligned, in descriptor-marker order) followed by one vertex pool (each
vtx_count*stride, same order); the vertex pool is 4-byte aligned after
the index pool. The whole resource is derived from one anchored pivot:
  ib0 = vb0 - span - pad   (pad in 0..=3, alignment)
  ib[i] = align4(ib[i-1] + idx_count[i-1]*2)
  vb[i] = vb[i-1] + vtx_count[i-1]*stride
vb0 is found via the unit-normal vertex-run scan; the alignment is
confirmed by validating the LARGEST sub-mesh (most reliable), after
which the rest are read/validated. A single marker reduces this to the
existing adjacency anchor, so grouped generalises it.

Results (cross-checked against a Canary GPU draw-log capture of
DeltaSaber_T.xpr):
- DeltaSaber_T f001 = body + 7 detail parts = 8650 tris, every sub-mesh
  0-degenerate / full-coverage / winding-agreement 1.000.
- All 19 previously-declined weapon models now decode (they hit pad 2
  and/or lead with a tiny bracket that broke a markers[0] pivot). Corpus
  audit: 0/146 geometry files fail (was 19 -> flat-texture in the viewer).
- Stages unchanged (single-marker path is byte-identical; grouped falls
  back to the old anchor on failure). 7/7 disc tests green incl. the
  strict stage quality audit; new hero_ship_grouped_pool_decodes test.

Viewer: route by count_xbg7; --only matches an exact model name (so the
neutral pose renders without the mnv*/turn180 animation poses). Fix the
albedo matcher: match a sub-model to its _col map by entity stem
(e007_bdy_01 -> e007_col) instead of a full-name prefix, lifting stage
sub-model texturing from ~25% to ~95% (the rest were flat grey). Colour
correctness (channel order/sRGB) remains a separate dynamic-RE item.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

crates/sylpheed-cli/src/main.rs

@@ -423,17 +423,30 @@ fn cmd_texture_export(file: &Path, output: &Path) -> Result<()> {
 /// a single model (weapon / prop) OR a stage's many sub-models — whichever
 /// yields more geometry.
 fn decode_models(bytes: &[u8]) -> Vec<sylpheed_formats::mesh::Xbg7Model> {
-    use sylpheed_formats::mesh::Xbg7Model;
-    let single = Xbg7Model::from_xpr2(bytes)
+    use sylpheed_formats::mesh::{count_xbg7, Xbg7Model};
+    // Route by container kind, NOT by whichever decoder yields more verts (that
+    // old heuristic let `stage_models`' content-anchoring win on single-model
+    // files, fabricating phantom / duplicate / mis-anchored blocks). A file with
+    // one XBG7 resource is a single model (weapon / prop) → use only the
+    // validated records-based list decode; content-anchoring a single-model file
+    // invents geometry. Many XBG7 resources → a Stage_* collection → anchor them.
+    if count_xbg7(bytes) > 1 {
+        // Multi-resource Stage_* collection → content-anchor every resource
+        // (each anchor now gated by stored-normal agreement).
+        Xbg7Model::stage_models(bytes)
+    } else if let Some(m) = Xbg7Model::from_xpr2(bytes)
         .ok()
-        .filter(|m| !m.meshes.is_empty());
-    let single_verts = single.as_ref().map(|m| m.totals().0).unwrap_or(0);
-    let stage = Xbg7Model::stage_models(bytes);
-    let stage_verts: usize = stage.iter().map(|m| m.totals().0).sum();
-    if !stage.is_empty() && stage_verts > single_verts {
-        stage
+        .filter(|m| !m.meshes.is_empty())
+    {
+        // Single model the records-based list decode carved (authoritative).
+        vec![m]
     } else {
-        single.into_iter().collect()
+        // Single model from_xpr2 couldn't locate (its sequential carve missed
+        // the block) — fall back to content-anchoring, which finds it by shape.
+        // Use a STRICT winding-consistency gate (0.85): on a single-model file a
+        // mis-anchor is an obvious phantom / spike-mess and must be declined,
+        // unlike the large stage corpus which keeps the ungated path.
+        Xbg7Model::anchor_models(bytes, 0.85)
     }
 }
 
@@ -536,7 +549,14 @@ fn cmd_mesh_render(
     let bytes = std::fs::read(file).with_context(|| format!("Cannot read {}", file.display()))?;
     let mut models = decode_models(&bytes);
     if let Some(sub) = &only {
-        models.retain(|m| m.name.contains(sub.as_str()));
+        // Prefer an exact name match (e.g. `f001` for the neutral ship pose,
+        // excluding the `_rou_f001_mnv*` animation poses that also *contain*
+        // "f001"); fall back to substring when nothing matches exactly.
+        if models.iter().any(|m| m.name == *sub) {
+            models.retain(|m| m.name == *sub);
+        } else {
+            models.retain(|m| m.name.contains(sub.as_str()));
+        }
     }
     if models.is_empty() {
         anyhow::bail!("no decodable XBG7 geometry in {}", file.display());