为所有函数和类添加中文注释文档字符串

app/exercises/dead_bug/state_machine.py

@@ -3,9 +3,11 @@ from __future__ import annotations
 from app.exercises.dead_bug.rules import detect_diagonal_extension, is_ready_position
 from app.exercises.dead_bug.types import DeadBugMetrics, DeadBugPhase, DeadBugResult
 
-
 class DeadBugStateMachine:
+    """死虫式动作状态机：管理READY/EXTENDING/NEED_RESET/NO_POSE状态转换"""
+
     def __init__(self, *, extension_confirm_frames: int = 4, reset_confirm_frames: int = 3) -> None:
+        """初始化并设置状态转换确认帧数"""
         self.extension_confirm_frames = extension_confirm_frames
         self.reset_confirm_frames = reset_confirm_frames
 
@@ -17,6 +19,7 @@ class DeadBugStateMachine:
         self._reset_frames = 0
 
     def update(self, metrics: DeadBugMetrics) -> DeadBugResult:
+        """根据传入指标更新状态机并返回本次结果"""
         side = detect_diagonal_extension(metrics)
         ready = is_ready_position(metrics)