前端进度条性能优化、仿真结束后后处理优化；后端C代码生成流程优化：先识别来源，再按照已知未知量需求排序，最后局部求解

app/simulation/native_codegen/tolerances.py

@@ -0,0 +1,16 @@
+"""SI absolute error floors shared by both native code generators.
+
+Mass must not inherit the energy floor: 1e-8 kg overwhelmed relative error
+control in small pipe volumes. These conservative defaults were validated on
+the pipe and chamber regressions; model-scale/user tolerance settings remain
+a separate protocol change.
+"""
+
+
+def state_absolute_tolerance(key: str) -> str:
+    field = key.rsplit('.', 1)[-1]
+    if field in ('m', 'm1', 'm2'):
+        return '1e-14'  # kg
+    if field in ('v', 'x'):
+        return '1e-12'  # m/s or m
+    return '1e-8'  # J (or the internal constant state of an algebraic model)