diff --git a/Tools/ModelTranslator/README.md b/Tools/ModelTranslator/README.md
index ad8bfb3e..3b4a9c50 100644
--- a/Tools/ModelTranslator/README.md
+++ b/Tools/ModelTranslator/README.md
@@ -46,7 +46,7 @@ python model_translator.py out_bake/well1500/well1500.fbx    # -> out/well1500/
 ```
 
 - **model_decimate.py**：多 mesh 自动 join；三角化后 Decimate(collapse) 减到 `--tris`（±3%，最多 2 轮修正）；旧 UV 全删后重展——默认锐边标 seam + MINIMUM_STRETCH 整岛展开（碎岛少、接缝落在硬边），质量不达标（翻转 >2% 或重叠 >8%）自动回退 Smart UV Project，`--unwrap smart` 可强制旧行为；输出 `<名>_low.fbx`（`-o` 改目录），日志报 UV 岛数/利用率
-- **model_bake.py**：Cycles selected-to-active 烘焙。normal（切线空间 OpenGL +Y）/ao 直接烘；color/metallic/roughness 把高模 Principled 对应输入接 Emission 烘 EMIT。`--size` 默认 2048，`--samples` AO 采样默认 64，射线距离默认低模包围盒对角线 2%（`--ray-distance` 覆盖）；低模无 UV 会报错，高低模包围盒差超 10% 打警告；导入后自动应用物体变换——未应用缩放的 FBX（如 cm 单位导出的 scale=0.01）会把射线距离缩到近零导致大面积烘空（脏色）
+- **model_bake.py**：Cycles selected-to-active 烘焙。normal（切线空间 OpenGL +Y）/ao 直接烘；color/metallic/roughness 把高模 Principled 对应输入接 Emission 烘 EMIT。`--size` 默认 2048，`--samples` AO 采样默认 64，射线距离默认低模包围盒对角线 2%（`--ray-distance` 覆盖）；低模无 UV 会报错，高低模包围盒差超 10% 打警告；导入后自动应用物体变换——未应用缩放的 FBX（如 cm 单位导出的 scale=0.01）会把射线距离缩到近零导致大面积烘空（脏色）；固定 `-t 1` 单线程跑 Blender——5.0 的 selected-to-active 射线求交多线程有竞争，会随机 EXCEPTION_ACCESS_VIOLATION 崩溃
 - 输出命名 `<名>_color/normal/metallic/roughness/ao.png`，正好命中转换器的纯网格贴图命名约定
 
 ## 转换规则
diff --git a/Tools/ModelTranslator/model_bake.py b/Tools/ModelTranslator/model_bake.py
index 8007ffa5..39afb0f2 100644
--- a/Tools/ModelTranslator/model_bake.py
+++ b/Tools/ModelTranslator/model_bake.py
@@ -25,9 +25,12 @@ def main():
     stem = output_stem(os.path.splitext(os.path.basename(args.low))[0])
     outdir = os.path.join(args.out, stem)
     ray = "auto" if args.ray_distance is None else str(args.ray_distance)
+    # -t 1：Blender 5.0 的 selected-to-active 烘焙射线求交是多线程的（cast_ray_highpoly
+    # / TBB parallel_for），存在竞争会随机 EXCEPTION_ACCESS_VIOLATION 崩溃；单线程稳定
     s = run_blender_script(blender, "bl_bake.py",
                            [args.high, args.low, outdir, str(args.size),
-                            ray, str(args.samples)])
+                            ray, str(args.samples)],
+                           blender_args=("-t", "1"))
     print("== %s（高 %d 面 / 低 %d 面，射线距离 %.4f）-> %s" %
           (s["stem"], s["high_tris"], s["low_tris"], s["ray_distance"], outdir))
     for name, fname in s["outputs"].items():
diff --git a/Tools/ModelTranslator/mt_run.py b/Tools/ModelTranslator/mt_run.py
index 3e7bc0f2..1031023c 100644
--- a/Tools/ModelTranslator/mt_run.py
+++ b/Tools/ModelTranslator/mt_run.py
@@ -18,9 +18,9 @@ def find_blender(cli_arg):
     sys.exit("找不到 blender.exe，请用 --blender 指定或设置环境变量 BLENDER_EXE")
 
 
-def run_blender_script(blender, script, script_args):
+def run_blender_script(blender, script, script_args, blender_args=()):
     """跑 HERE 下的 bl_*.py，返回 MT_SUMMARY JSON；失败或 summary 带 error 则退出。"""
-    cmd = [blender, "-b", "--factory-startup",
+    cmd = [blender, "-b", *blender_args, "--factory-startup",
            "--python", os.path.join(HERE, script), "--"] + list(script_args)
     proc = subprocess.run(cmd, capture_output=True, text=True, encoding="utf-8",
                           errors="replace")
diff --git a/Tools/ModelTranslator/tests/bl_diag_mesh.py b/Tools/ModelTranslator/tests/bl_diag_mesh.py
new file mode 100644
index 00000000..3575b744
--- /dev/null
+++ b/Tools/ModelTranslator/tests/bl_diag_mesh.py
@@ -0,0 +1,60 @@
+"""诊断：导入 FBX 检查几何是否损坏（NaN 顶点/退化面/validate 修复量）。
+用法：blender -b --factory-startup --python tests/bl_diag_mesh.py -- <model.fbx> [apply]
+"""
+import math
+import os
+import sys
+
+sys.path.insert(0, os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
+
+
+def main():
+    import bpy
+    from bl_decimate import join_meshes
+    argv = sys.argv[sys.argv.index("--") + 1:]
+    path = argv[0]
+    do_apply = len(argv) > 1 and argv[1] == "apply"
+
+    bpy.ops.wm.read_factory_settings(use_empty=True)
+    before = set(bpy.data.objects)
+    bpy.ops.import_scene.fbx(filepath=path)
+    new = [o for o in bpy.data.objects if o not in before]
+    meshes = [o for o in new if o.type == 'MESH']
+    print("DIAG objects=%d meshes=%d" % (len(new), len(meshes)))
+    for o in new:
+        print("DIAG   obj=%r type=%s scale=%s" % (o.name, o.type, tuple(round(s, 4) for s in o.scale)))
+    obj = join_meshes(meshes)
+    if do_apply:
+        bpy.ops.object.select_all(action='DESELECT')
+        obj.select_set(True)
+        bpy.context.view_layer.objects.active = obj
+        bpy.ops.object.transform_apply(location=True, rotation=True, scale=True)
+        print("DIAG transform applied")
+
+    me = obj.data
+    print("DIAG verts=%d polys=%d dims=%s" % (
+        len(me.vertices), len(me.polygons),
+        tuple(round(d, 4) for d in obj.dimensions)))
+
+    nan_verts = 0
+    huge_verts = 0
+    for v in me.vertices:
+        x, y, z = v.co
+        if any(math.isnan(c) or math.isinf(c) for c in (x, y, z)):
+            nan_verts += 1
+        elif max(abs(x), abs(y), abs(z)) > 1e6:
+            huge_verts += 1
+    print("DIAG nan_verts=%d huge_verts=%d" % (nan_verts, huge_verts))
+
+    zero_area = sum(1 for p in me.polygons if p.area < 1e-12)
+    print("DIAG zero_area_polys=%d" % zero_area)
+
+    # validate(verbose) 会打印它修的每个问题；返回 True 表示有改动
+    changed = me.validate(verbose=True)
+    print("DIAG validate_changed=%s" % changed)
+    print("DIAG after_validate verts=%d polys=%d" % (len(me.vertices), len(me.polygons)))
+    print("DIAG DONE")
+
+
+if __name__ == "__main__" and "--" in sys.argv:
+    main()