Refactor documentation structure and add new specifications

- Updated MSH documentation to reflect changes in material, wear, and texture specifications.
- Introduced new `render.md` file detailing the render pipeline process.
- Removed outdated sections from `runtime-pipeline.md` and redirected to `render.md`.
- Added detailed specifications for `Texm` texture format and `WEAR` wear table.
- Updated navigation in `mkdocs.yml` to align with new documentation structure.

5 files changed, 783 insertions, 0 deletions

diff --git a/crates/msh-core/Cargo.toml b/crates/msh-core/Cargo.toml
new file mode 100644
index 0000000..cdea317
--- /dev/null
+++ b/crates/msh-core/Cargo.toml
@@ -0,0 +1,7 @@
+[package]
+name = "msh-core"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+nres = { path = "../nres" }
diff --git a/crates/msh-core/README.md b/crates/msh-core/README.md
new file mode 100644
index 0000000..016df7a
--- /dev/null
+++ b/crates/msh-core/README.md
@@ -0,0 +1,14 @@
+# msh-core
+
+Парсер core-части формата `MSH`.
+
+Покрывает:
+
+- `Res1`, `Res2`, `Res3`, `Res6`, `Res13` (обязательные);
+- `Res4`, `Res5`, `Res10` (опциональные);
+- slot lookup по `node/lod/group`.
+
+Тесты:
+
+- прогон по всем `.msh` в `testdata`;
+- синтетическая минимальная модель.
diff --git a/crates/msh-core/src/error.rs b/crates/msh-core/src/error.rs
new file mode 100644
index 0000000..81fe54f
--- /dev/null
+++ b/crates/msh-core/src/error.rs
@@ -0,0 +1,74 @@
+use core::fmt;
+
+#[derive(Debug)]
+pub enum Error {
+    Nres(nres::error::Error),
+    MissingResource {
+        kind: u32,
+        label: &'static str,
+    },
+    InvalidResourceSize {
+        label: &'static str,
+        size: usize,
+        stride: usize,
+    },
+    InvalidRes2Size {
+        size: usize,
+    },
+    UnsupportedNodeStride {
+        stride: usize,
+    },
+    IndexOutOfBounds {
+        label: &'static str,
+        index: usize,
+        limit: usize,
+    },
+    IntegerOverflow,
+}
+
+impl From<nres::error::Error> for Error {
+    fn from(value: nres::error::Error) -> Self {
+        Self::Nres(value)
+    }
+}
+
+impl fmt::Display for Error {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            Self::Nres(err) => write!(f, "{err}"),
+            Self::MissingResource { kind, label } => {
+                write!(f, "missing required resource type={kind} ({label})")
+            }
+            Self::InvalidResourceSize {
+                label,
+                size,
+                stride,
+            } => {
+                write!(
+                    f,
+                    "invalid {label} size={size}, expected multiple of stride={stride}"
+                )
+            }
+            Self::InvalidRes2Size { size } => {
+                write!(f, "invalid Res2 size={size}, expected >= 140")
+            }
+            Self::UnsupportedNodeStride { stride } => {
+                write!(
+                    f,
+                    "unsupported Res1 node stride={stride}, expected 38 or 24"
+                )
+            }
+            Self::IndexOutOfBounds {
+                label,
+                index,
+                limit,
+            } => write!(
+                f,
+                "{label} index out of bounds: index={index}, limit={limit}"
+            ),
+            Self::IntegerOverflow => write!(f, "integer overflow"),
+        }
+    }
+}
+
+impl std::error::Error for Error {}
diff --git a/crates/msh-core/src/lib.rs b/crates/msh-core/src/lib.rs
new file mode 100644
index 0000000..84e8a86
--- /dev/null
+++ b/crates/msh-core/src/lib.rs
@@ -0,0 +1,392 @@
+pub mod error;
+
+use crate::error::Error;
+use std::sync::Arc;
+
+pub type Result<T> = core::result::Result<T, Error>;
+
+pub const RES1_NODE_TABLE: u32 = 1;
+pub const RES2_SLOTS: u32 = 2;
+pub const RES3_POSITIONS: u32 = 3;
+pub const RES4_NORMALS: u32 = 4;
+pub const RES5_UV0: u32 = 5;
+pub const RES6_INDICES: u32 = 6;
+pub const RES10_NAMES: u32 = 10;
+pub const RES13_BATCHES: u32 = 13;
+
+#[derive(Clone, Debug)]
+pub struct Slot {
+    pub tri_start: u16,
+    pub tri_count: u16,
+    pub batch_start: u16,
+    pub batch_count: u16,
+    pub aabb_min: [f32; 3],
+    pub aabb_max: [f32; 3],
+    pub sphere_center: [f32; 3],
+    pub sphere_radius: f32,
+    pub opaque: [u32; 5],
+}
+
+#[derive(Clone, Debug)]
+pub struct Batch {
+    pub batch_flags: u16,
+    pub material_index: u16,
+    pub opaque4: u16,
+    pub opaque6: u16,
+    pub index_count: u16,
+    pub index_start: u32,
+    pub opaque14: u16,
+    pub base_vertex: u32,
+}
+
+#[derive(Clone, Debug)]
+pub struct Model {
+    pub node_stride: usize,
+    pub node_count: usize,
+    pub nodes_raw: Vec<u8>,
+    pub slots: Vec<Slot>,
+    pub positions: Vec<[f32; 3]>,
+    pub normals: Option<Vec<[i8; 4]>>,
+    pub uv0: Option<Vec<[i16; 2]>>,
+    pub indices: Vec<u16>,
+    pub batches: Vec<Batch>,
+    pub node_names: Option<Vec<Option<String>>>,
+}
+
+impl Model {
+    pub fn slot_index(&self, node_index: usize, lod: usize, group: usize) -> Option<usize> {
+        if node_index >= self.node_count || lod >= 3 || group >= 5 {
+            return None;
+        }
+        if self.node_stride != 38 {
+            return None;
+        }
+        let node_off = node_index.checked_mul(self.node_stride)?;
+        let matrix_off = node_off.checked_add(8)?;
+        let word_off = matrix_off.checked_add((lod * 5 + group) * 2)?;
+        let raw = read_u16(&self.nodes_raw, word_off).ok()?;
+        if raw == u16::MAX {
+            return None;
+        }
+        let idx = usize::from(raw);
+        if idx >= self.slots.len() {
+            return None;
+        }
+        Some(idx)
+    }
+}
+
+pub fn parse_model_payload(payload: &[u8]) -> Result<Model> {
+    let archive = nres::Archive::open_bytes(
+        Arc::from(payload.to_vec().into_boxed_slice()),
+        nres::OpenOptions::default(),
+    )?;
+
+    let res1 = read_required(&archive, RES1_NODE_TABLE, "Res1")?;
+    let res2 = read_required(&archive, RES2_SLOTS, "Res2")?;
+    let res3 = read_required(&archive, RES3_POSITIONS, "Res3")?;
+    let res6 = read_required(&archive, RES6_INDICES, "Res6")?;
+    let res13 = read_required(&archive, RES13_BATCHES, "Res13")?;
+
+    let res4 = read_optional(&archive, RES4_NORMALS)?;
+    let res5 = read_optional(&archive, RES5_UV0)?;
+    let res10 = read_optional(&archive, RES10_NAMES)?;
+
+    let node_stride = usize::try_from(res1.meta.attr3).map_err(|_| Error::IntegerOverflow)?;
+    if node_stride != 38 && node_stride != 24 {
+        return Err(Error::UnsupportedNodeStride {
+            stride: node_stride,
+        });
+    }
+    if res1.bytes.len() % node_stride != 0 {
+        return Err(Error::InvalidResourceSize {
+            label: "Res1",
+            size: res1.bytes.len(),
+            stride: node_stride,
+        });
+    }
+    let node_count = res1.bytes.len() / node_stride;
+
+    if res2.bytes.len() < 0x8C {
+        return Err(Error::InvalidRes2Size {
+            size: res2.bytes.len(),
+        });
+    }
+    let slot_blob = res2
+        .bytes
+        .len()
+        .checked_sub(0x8C)
+        .ok_or(Error::IntegerOverflow)?;
+    if slot_blob % 68 != 0 {
+        return Err(Error::InvalidResourceSize {
+            label: "Res2.slots",
+            size: slot_blob,
+            stride: 68,
+        });
+    }
+    let slot_count = slot_blob / 68;
+    let mut slots = Vec::with_capacity(slot_count);
+    for i in 0..slot_count {
+        let off = 0x8Cusize
+            .checked_add(i.checked_mul(68).ok_or(Error::IntegerOverflow)?)
+            .ok_or(Error::IntegerOverflow)?;
+        slots.push(Slot {
+            tri_start: read_u16(&res2.bytes, off)?,
+            tri_count: read_u16(&res2.bytes, off + 2)?,
+            batch_start: read_u16(&res2.bytes, off + 4)?,
+            batch_count: read_u16(&res2.bytes, off + 6)?,
+            aabb_min: [
+                read_f32(&res2.bytes, off + 8)?,
+                read_f32(&res2.bytes, off + 12)?,
+                read_f32(&res2.bytes, off + 16)?,
+            ],
+            aabb_max: [
+                read_f32(&res2.bytes, off + 20)?,
+                read_f32(&res2.bytes, off + 24)?,
+                read_f32(&res2.bytes, off + 28)?,
+            ],
+            sphere_center: [
+                read_f32(&res2.bytes, off + 32)?,
+                read_f32(&res2.bytes, off + 36)?,
+                read_f32(&res2.bytes, off + 40)?,
+            ],
+            sphere_radius: read_f32(&res2.bytes, off + 44)?,
+            opaque: [
+                read_u32(&res2.bytes, off + 48)?,
+                read_u32(&res2.bytes, off + 52)?,
+                read_u32(&res2.bytes, off + 56)?,
+                read_u32(&res2.bytes, off + 60)?,
+                read_u32(&res2.bytes, off + 64)?,
+            ],
+        });
+    }
+
+    let positions = parse_positions(&res3.bytes)?;
+    let indices = parse_u16_array(&res6.bytes, "Res6")?;
+    let batches = parse_batches(&res13.bytes)?;
+
+    let normals = match res4 {
+        Some(raw) => Some(parse_i8x4_array(&raw.bytes, "Res4")?),
+        None => None,
+    };
+    let uv0 = match res5 {
+        Some(raw) => Some(parse_i16x2_array(&raw.bytes, "Res5")?),
+        None => None,
+    };
+    let node_names = match res10 {
+        Some(raw) => Some(parse_res10_names(&raw.bytes, node_count)?),
+        None => None,
+    };
+
+    Ok(Model {
+        node_stride,
+        node_count,
+        nodes_raw: res1.bytes,
+        slots,
+        positions,
+        normals,
+        uv0,
+        indices,
+        batches,
+        node_names,
+    })
+}
+
+fn parse_positions(data: &[u8]) -> Result<Vec<[f32; 3]>> {
+    if !data.len().is_multiple_of(12) {
+        return Err(Error::InvalidResourceSize {
+            label: "Res3",
+            size: data.len(),
+            stride: 12,
+        });
+    }
+    let count = data.len() / 12;
+    let mut out = Vec::with_capacity(count);
+    for i in 0..count {
+        let off = i * 12;
+        out.push([
+            read_f32(data, off)?,
+            read_f32(data, off + 4)?,
+            read_f32(data, off + 8)?,
+        ]);
+    }
+    Ok(out)
+}
+
+fn parse_batches(data: &[u8]) -> Result<Vec<Batch>> {
+    if !data.len().is_multiple_of(20) {
+        return Err(Error::InvalidResourceSize {
+            label: "Res13",
+            size: data.len(),
+            stride: 20,
+        });
+    }
+    let count = data.len() / 20;
+    let mut out = Vec::with_capacity(count);
+    for i in 0..count {
+        let off = i * 20;
+        out.push(Batch {
+            batch_flags: read_u16(data, off)?,
+            material_index: read_u16(data, off + 2)?,
+            opaque4: read_u16(data, off + 4)?,
+            opaque6: read_u16(data, off + 6)?,
+            index_count: read_u16(data, off + 8)?,
+            index_start: read_u32(data, off + 10)?,
+            opaque14: read_u16(data, off + 14)?,
+            base_vertex: read_u32(data, off + 16)?,
+        });
+    }
+    Ok(out)
+}
+
+fn parse_u16_array(data: &[u8], label: &'static str) -> Result<Vec<u16>> {
+    if !data.len().is_multiple_of(2) {
+        return Err(Error::InvalidResourceSize {
+            label,
+            size: data.len(),
+            stride: 2,
+        });
+    }
+    let mut out = Vec::with_capacity(data.len() / 2);
+    for i in (0..data.len()).step_by(2) {
+        out.push(read_u16(data, i)?);
+    }
+    Ok(out)
+}
+
+fn parse_i8x4_array(data: &[u8], label: &'static str) -> Result<Vec<[i8; 4]>> {
+    if !data.len().is_multiple_of(4) {
+        return Err(Error::InvalidResourceSize {
+            label,
+            size: data.len(),
+            stride: 4,
+        });
+    }
+    let mut out = Vec::with_capacity(data.len() / 4);
+    for i in (0..data.len()).step_by(4) {
+        out.push([
+            read_i8(data, i)?,
+            read_i8(data, i + 1)?,
+            read_i8(data, i + 2)?,
+            read_i8(data, i + 3)?,
+        ]);
+    }
+    Ok(out)
+}
+
+fn parse_i16x2_array(data: &[u8], label: &'static str) -> Result<Vec<[i16; 2]>> {
+    if !data.len().is_multiple_of(4) {
+        return Err(Error::InvalidResourceSize {
+            label,
+            size: data.len(),
+            stride: 4,
+        });
+    }
+    let mut out = Vec::with_capacity(data.len() / 4);
+    for i in (0..data.len()).step_by(4) {
+        out.push([read_i16(data, i)?, read_i16(data, i + 2)?]);
+    }
+    Ok(out)
+}
+
+fn parse_res10_names(data: &[u8], node_count: usize) -> Result<Vec<Option<String>>> {
+    let mut out = Vec::with_capacity(node_count);
+    let mut off = 0usize;
+    for _ in 0..node_count {
+        let len = usize::try_from(read_u32(data, off)?).map_err(|_| Error::IntegerOverflow)?;
+        off = off.checked_add(4).ok_or(Error::IntegerOverflow)?;
+        if len == 0 {
+            out.push(None);
+            continue;
+        }
+        let need = len.checked_add(1).ok_or(Error::IntegerOverflow)?;
+        let end = off.checked_add(need).ok_or(Error::IntegerOverflow)?;
+        let slice = data.get(off..end).ok_or(Error::InvalidResourceSize {
+            label: "Res10",
+            size: data.len(),
+            stride: 1,
+        })?;
+        let text = if slice.last().copied() == Some(0) {
+            &slice[..slice.len().saturating_sub(1)]
+        } else {
+            slice
+        };
+        let decoded = String::from_utf8_lossy(text).to_string();
+        out.push(Some(decoded));
+        off = end;
+    }
+    Ok(out)
+}
+
+struct RawResource {
+    meta: nres::EntryMeta,
+    bytes: Vec<u8>,
+}
+
+fn read_required(archive: &nres::Archive, kind: u32, label: &'static str) -> Result<RawResource> {
+    let id = archive
+        .entries()
+        .find(|entry| entry.meta.kind == kind)
+        .map(|entry| entry.id)
+        .ok_or(Error::MissingResource { kind, label })?;
+    let entry = archive.get(id).ok_or(Error::IndexOutOfBounds {
+        label,
+        index: usize::try_from(id.0).map_err(|_| Error::IntegerOverflow)?,
+        limit: archive.entry_count(),
+    })?;
+    let data = archive.read(id)?.into_owned();
+    Ok(RawResource {
+        meta: entry.meta.clone(),
+        bytes: data,
+    })
+}
+
+fn read_optional(archive: &nres::Archive, kind: u32) -> Result<Option<RawResource>> {
+    let Some(id) = archive
+        .entries()
+        .find(|entry| entry.meta.kind == kind)
+        .map(|entry| entry.id)
+    else {
+        return Ok(None);
+    };
+    let entry = archive.get(id).ok_or(Error::IndexOutOfBounds {
+        label: "optional",
+        index: usize::try_from(id.0).map_err(|_| Error::IntegerOverflow)?,
+        limit: archive.entry_count(),
+    })?;
+    let data = archive.read(id)?.into_owned();
+    Ok(Some(RawResource {
+        meta: entry.meta.clone(),
+        bytes: data,
+    }))
+}
+
+fn read_u16(data: &[u8], offset: usize) -> Result<u16> {
+    let bytes = data.get(offset..offset + 2).ok_or(Error::IntegerOverflow)?;
+    let arr: [u8; 2] = bytes.try_into().map_err(|_| Error::IntegerOverflow)?;
+    Ok(u16::from_le_bytes(arr))
+}
+
+fn read_i16(data: &[u8], offset: usize) -> Result<i16> {
+    let bytes = data.get(offset..offset + 2).ok_or(Error::IntegerOverflow)?;
+    let arr: [u8; 2] = bytes.try_into().map_err(|_| Error::IntegerOverflow)?;
+    Ok(i16::from_le_bytes(arr))
+}
+
+fn read_i8(data: &[u8], offset: usize) -> Result<i8> {
+    let byte = data.get(offset).copied().ok_or(Error::IntegerOverflow)?;
+    Ok(i8::from_le_bytes([byte]))
+}
+
+fn read_u32(data: &[u8], offset: usize) -> Result<u32> {
+    let bytes = data.get(offset..offset + 4).ok_or(Error::IntegerOverflow)?;
+    let arr: [u8; 4] = bytes.try_into().map_err(|_| Error::IntegerOverflow)?;
+    Ok(u32::from_le_bytes(arr))
+}
+
+fn read_f32(data: &[u8], offset: usize) -> Result<f32> {
+    Ok(f32::from_bits(read_u32(data, offset)?))
+}
+
+#[cfg(test)]
+mod tests;
diff --git a/crates/msh-core/src/tests.rs b/crates/msh-core/src/tests.rs
new file mode 100644
index 0000000..1eefb31
--- /dev/null
+++ b/crates/msh-core/src/tests.rs
@@ -0,0 +1,296 @@
+use super::*;
+use nres::Archive;
+use std::fs;
+use std::path::{Path, PathBuf};
+
+fn collect_files_recursive(root: &Path, out: &mut Vec<PathBuf>) {
+    let Ok(entries) = fs::read_dir(root) else {
+        return;
+    };
+    for entry in entries.flatten() {
+        let path = entry.path();
+        if path.is_dir() {
+            collect_files_recursive(&path, out);
+        } else if path.is_file() {
+            out.push(path);
+        }
+    }
+}
+
+fn nres_test_files() -> Vec<PathBuf> {
+    let root = Path::new(env!("CARGO_MANIFEST_DIR"))
+        .join("..")
+        .join("..")
+        .join("testdata");
+    let mut files = Vec::new();
+    collect_files_recursive(&root, &mut files);
+    files.sort();
+    files
+        .into_iter()
+        .filter(|path| {
+            fs::read(path)
+                .map(|bytes| bytes.get(0..4) == Some(b"NRes"))
+                .unwrap_or(false)
+        })
+        .collect()
+}
+
+fn is_msh_name(name: &str) -> bool {
+    name.to_ascii_lowercase().ends_with(".msh")
+}
+
+#[test]
+fn parse_all_game_msh_models() {
+    let archives = nres_test_files();
+    if archives.is_empty() {
+        eprintln!("skipping parse_all_game_msh_models: no NRes files in testdata");
+        return;
+    }
+
+    let mut model_count = 0usize;
+    let mut renderable_count = 0usize;
+    let mut legacy_stride24_count = 0usize;
+
+    for archive_path in archives {
+        let archive = Archive::open_path(&archive_path)
+            .unwrap_or_else(|err| panic!("failed to open {}: {err}", archive_path.display()));
+
+        for entry in archive.entries() {
+            if !is_msh_name(&entry.meta.name) {
+                continue;
+            }
+            model_count += 1;
+            let payload = archive.read(entry.id).unwrap_or_else(|err| {
+                panic!(
+                    "failed to read model '{}' in {}: {err}",
+                    entry.meta.name,
+                    archive_path.display()
+                )
+            });
+            let model = parse_model_payload(payload.as_slice()).unwrap_or_else(|err| {
+                panic!(
+                    "failed to parse model '{}' in {}: {err}",
+                    entry.meta.name,
+                    archive_path.display()
+                )
+            });
+
+            if model.node_stride == 24 {
+                legacy_stride24_count += 1;
+            }
+
+            for node_index in 0..model.node_count {
+                for lod in 0..3 {
+                    for group in 0..5 {
+                        if let Some(slot_idx) = model.slot_index(node_index, lod, group) {
+                            assert!(
+                                slot_idx < model.slots.len(),
+                                "slot index out of bounds in '{}' ({})",
+                                entry.meta.name,
+                                archive_path.display()
+                            );
+                        }
+                    }
+                }
+            }
+
+            let mut has_renderable_batch = false;
+            for node_index in 0..model.node_count {
+                let Some(slot_idx) = model.slot_index(node_index, 0, 0) else {
+                    continue;
+                };
+                let slot = &model.slots[slot_idx];
+                let batch_end =
+                    usize::from(slot.batch_start).saturating_add(usize::from(slot.batch_count));
+                if batch_end > model.batches.len() {
+                    continue;
+                }
+                for batch in &model.batches[usize::from(slot.batch_start)..batch_end] {
+                    let index_start = usize::try_from(batch.index_start).unwrap_or(usize::MAX);
+                    let index_count = usize::from(batch.index_count);
+                    let end = index_start.saturating_add(index_count);
+                    if end <= model.indices.len() && index_count >= 3 {
+                        has_renderable_batch = true;
+                        break;
+                    }
+                }
+                if has_renderable_batch {
+                    break;
+                }
+            }
+            if has_renderable_batch {
+                renderable_count += 1;
+            }
+        }
+    }
+
+    assert!(model_count > 0, "no .msh entries found");
+    assert!(
+        renderable_count > 0,
+        "no renderable models (lod0/group0) were detected"
+    );
+    assert!(
+        legacy_stride24_count <= model_count,
+        "internal test accounting error"
+    );
+}
+
+#[test]
+fn parse_minimal_synthetic_model() {
+    // Nested NRes with required resources only.
+    let mut payload = Vec::new();
+    payload.extend_from_slice(b"NRes");
+    payload.extend_from_slice(&0x100u32.to_le_bytes());
+    payload.extend_from_slice(&5u32.to_le_bytes()); // entry_count
+    payload.extend_from_slice(&0u32.to_le_bytes()); // total_size placeholder
+
+    let mut resource_offsets = Vec::new();
+    let mut resource_sizes = Vec::new();
+    let mut resource_types = Vec::new();
+    let mut resource_attr3 = Vec::new();
+    let mut resource_names = Vec::new();
+
+    let add_resource = |payload: &mut Vec<u8>,
+                        offsets: &mut Vec<u32>,
+                        sizes: &mut Vec<u32>,
+                        types: &mut Vec<u32>,
+                        attr3: &mut Vec<u32>,
+                        names: &mut Vec<String>,
+                        kind: u32,
+                        name: &str,
+                        data: &[u8],
+                        attr3_val: u32| {
+        offsets.push(u32::try_from(payload.len()).expect("offset overflow"));
+        payload.extend_from_slice(data);
+        while !payload.len().is_multiple_of(8) {
+            payload.push(0);
+        }
+        sizes.push(u32::try_from(data.len()).expect("size overflow"));
+        types.push(kind);
+        attr3.push(attr3_val);
+        names.push(name.to_string());
+    };
+
+    let node = {
+        let mut b = vec![0u8; 38];
+        // slot[0][0] = 0
+        b[8..10].copy_from_slice(&0u16.to_le_bytes());
+        for i in 1..15 {
+            let off = 8 + i * 2;
+            b[off..off + 2].copy_from_slice(&u16::MAX.to_le_bytes());
+        }
+        b
+    };
+    let mut res2 = vec![0u8; 0x8C + 68];
+    res2[0x8C..0x8C + 2].copy_from_slice(&0u16.to_le_bytes()); // tri_start
+    res2[0x8C + 2..0x8C + 4].copy_from_slice(&0u16.to_le_bytes()); // tri_count
+    res2[0x8C + 4..0x8C + 6].copy_from_slice(&0u16.to_le_bytes()); // batch_start
+    res2[0x8C + 6..0x8C + 8].copy_from_slice(&1u16.to_le_bytes()); // batch_count
+    let positions = [0f32, 0f32, 0f32, 1f32, 0f32, 0f32, 0f32, 1f32, 0f32]
+        .iter()
+        .flat_map(|v| v.to_le_bytes())
+        .collect::<Vec<_>>();
+    let indices = [0u16, 1, 2]
+        .iter()
+        .flat_map(|v| v.to_le_bytes())
+        .collect::<Vec<_>>();
+    let batch = {
+        let mut b = vec![0u8; 20];
+        b[0..2].copy_from_slice(&0u16.to_le_bytes());
+        b[2..4].copy_from_slice(&0u16.to_le_bytes());
+        b[8..10].copy_from_slice(&3u16.to_le_bytes()); // index_count
+        b[10..14].copy_from_slice(&0u32.to_le_bytes()); // index_start
+        b[16..20].copy_from_slice(&0u32.to_le_bytes()); // base_vertex
+        b
+    };
+
+    add_resource(
+        &mut payload,
+        &mut resource_offsets,
+        &mut resource_sizes,
+        &mut resource_types,
+        &mut resource_attr3,
+        &mut resource_names,
+        RES1_NODE_TABLE,
+        "Res1",
+        &node,
+        38,
+    );
+    add_resource(
+        &mut payload,
+        &mut resource_offsets,
+        &mut resource_sizes,
+        &mut resource_types,
+        &mut resource_attr3,
+        &mut resource_names,
+        RES2_SLOTS,
+        "Res2",
+        &res2,
+        68,
+    );
+    add_resource(
+        &mut payload,
+        &mut resource_offsets,
+        &mut resource_sizes,
+        &mut resource_types,
+        &mut resource_attr3,
+        &mut resource_names,
+        RES3_POSITIONS,
+        "Res3",
+        &positions,
+        12,
+    );
+    add_resource(
+        &mut payload,
+        &mut resource_offsets,
+        &mut resource_sizes,
+        &mut resource_types,
+        &mut resource_attr3,
+        &mut resource_names,
+        RES6_INDICES,
+        "Res6",
+        &indices,
+        2,
+    );
+    add_resource(
+        &mut payload,
+        &mut resource_offsets,
+        &mut resource_sizes,
+        &mut resource_types,
+        &mut resource_attr3,
+        &mut resource_names,
+        RES13_BATCHES,
+        "Res13",
+        &batch,
+        20,
+    );
+
+    let directory_offset = payload.len();
+    for i in 0..resource_types.len() {
+        payload.extend_from_slice(&resource_types[i].to_le_bytes());
+        payload.extend_from_slice(&1u32.to_le_bytes()); // attr1
+        payload.extend_from_slice(&0u32.to_le_bytes()); // attr2
+        payload.extend_from_slice(&resource_sizes[i].to_le_bytes());
+        payload.extend_from_slice(&resource_attr3[i].to_le_bytes());
+        let mut name_raw = [0u8; 36];
+        let bytes = resource_names[i].as_bytes();
+        name_raw[..bytes.len()].copy_from_slice(bytes);
+        payload.extend_from_slice(&name_raw);
+        payload.extend_from_slice(&resource_offsets[i].to_le_bytes());
+        payload.extend_from_slice(&(i as u32).to_le_bytes()); // sort index
+    }
+    let total_size = u32::try_from(payload.len()).expect("size overflow");
+    payload[12..16].copy_from_slice(&total_size.to_le_bytes());
+    assert_eq!(
+        directory_offset + resource_types.len() * 64,
+        payload.len(),
+        "synthetic nested NRes layout invalid"
+    );
+
+    let model = parse_model_payload(&payload).expect("failed to parse synthetic model");
+    assert_eq!(model.node_count, 1);
+    assert_eq!(model.positions.len(), 3);
+    assert_eq!(model.indices.len(), 3);
+    assert_eq!(model.batches.len(), 1);
+    assert_eq!(model.slot_index(0, 0, 0), Some(0));
+}