docs: document smoothing processing core

ClumsyPilot/ParkrobTrajplanner/PathSmoothing/LocalG2/LocalG2WindowPlanner.cs

@@ -7,11 +7,18 @@ using MultiWheelC.TrajectoryPlanning.Utils;
 
 namespace MultiWheelC.TrajectoryPlanning.PathSmoothing.LocalG2;
 
-/// <summary>按硬方向边界生成并合并局部 G2 曲率事件的候选窗口。</summary>
+/// <summary>在硬方向边界内为局部 G2 曲率事件生成、合并候选窗口；绝不让窗口跨越换向段。</summary>
 internal sealed class LocalG2WindowPlanner
 {
     private const double MergeToleranceMeters = 1e-9d;
 
+    /// <summary>按段索引排序曲率事件并生成每个区域可用的窗口变体。</summary>
+    /// <param name="originalPath">已准备的方向段路径，提供每段局部弧长范围。</param>
+    /// <param name="transitions">检测到的曲率过渡事件；局部弧长单位为 m。</param>
+    /// <param name="options">窗口长度、候选上限和偏移相关的 Local G2 只读选项。</param>
+    /// <param name="regions">成功时为按路径顺序排列的只读平滑区域；失败时为空集合。</param>
+    /// <param name="reason">失败时描述事件、段或窗口长度问题；成功时为空字符串。</param>
+    /// <returns>所有事件可在所属方向段内构造合法窗口时为 <see langword="true"/>；否则为 <see langword="false"/>。</returns>
     internal bool TryPlan(
         PreparedPath originalPath,
         IReadOnlyList<CurvatureTransition> transitions,