feat(exercise): 优化死虫式训练姿态检测算法

- 调整视频处理频率从每帧处理改为每2帧处理
- 添加膝角趋势平滑算法减少单帧抖动误判
- 改进对角伸展检测逻辑支持准备位手臂上举
- 优化状态机确保严格回到准备姿态才计数
- 添加姿态丢失时的候选帧清理机制
- 更新音频文件生成路径至resources目录
- 改进macOS音频生成使用AIFF格式提高质量
- 添加详细的帧处理日志输出间隔配置

tests/test_dead_bug_state_machine.py

@@ -26,6 +26,36 @@ class TestDeadBugStateMachine:
             feedback=[],
         )
 
+    def _both_legs_extended(self) -> DeadBugMetrics:
+        """构建双腿同时伸展的非标准姿态"""
+        return DeadBugMetrics(
+            left_arm_extended=True, right_arm_extended=True,
+            left_leg_extended=True, right_leg_extended=True,
+            left_elbow_angle=160, right_elbow_angle=160,
+            left_knee_angle=160, right_knee_angle=160,
+            feedback=[],
+        )
+
+    def _arms_extended_ready_legs(self) -> DeadBugMetrics:
+        """构建腿已收回但手臂未收回的姿态"""
+        return DeadBugMetrics(
+            left_arm_extended=True, right_arm_extended=True,
+            left_leg_extended=False, right_leg_extended=False,
+            left_elbow_angle=160, right_elbow_angle=160,
+            left_knee_angle=100, right_knee_angle=100,
+            feedback=[],
+        )
+
+    def _right_knee_angle(self, angle: float) -> DeadBugMetrics:
+        """构建右膝角连续变化但伸展布尔值尚未稳定的姿态"""
+        return DeadBugMetrics(
+            left_arm_extended=True, right_arm_extended=True,
+            left_leg_extended=False, right_leg_extended=False,
+            left_elbow_angle=160, right_elbow_angle=160,
+            left_knee_angle=90, right_knee_angle=angle,
+            feedback=[],
+        )
+
     def test_initial_state(self):
         """测试：状态机初始化后应为READY且计数为0"""
         sm = DeadBugStateMachine()
@@ -46,3 +76,58 @@ class TestDeadBugStateMachine:
         assert sm.phase == DeadBugPhase.READY
         sm.update(self._extended_left())
         assert sm.phase == DeadBugPhase.EXTENDING
+
+    def test_confirm_extension_from_knee_angle_trend(self):
+        """测试：膝角连续上升时，不依赖单帧伸展布尔值也能确认伸展"""
+        sm = DeadBugStateMachine(extension_confirm_frames=2, reset_confirm_frames=2)
+
+        sm.update(self._right_knee_angle(100))
+        sm.update(self._right_knee_angle(130))
+        assert sm.phase == DeadBugPhase.READY
+        sm.update(self._right_knee_angle(145))
+        sm.update(self._right_knee_angle(150))
+
+        assert sm.phase == DeadBugPhase.EXTENDING
+
+    def test_full_rep_counts_once_after_strict_reset(self):
+        """测试：确认伸展后，只有严格回到准备姿态才计一次"""
+        sm = DeadBugStateMachine(extension_confirm_frames=2, reset_confirm_frames=2)
+
+        sm.update(self._extended_left())
+        sm.update(self._extended_left())
+        assert sm.phase == DeadBugPhase.EXTENDING
+
+        sm.update(self._arms_extended_ready_legs())
+        assert sm.rep_count == 0
+        assert sm.phase == DeadBugPhase.NEED_RESET
+
+        sm.update(self._ready_metrics())
+        result = sm.update(self._ready_metrics())
+        assert result.rep_count == 1
+        assert sm.phase == DeadBugPhase.READY
+
+        result = sm.update(self._ready_metrics())
+        assert result.rep_count == 1
+
+    def test_both_legs_do_not_start_rep(self):
+        """测试：双腿同时伸展不进入计数流程"""
+        sm = DeadBugStateMachine(extension_confirm_frames=2, reset_confirm_frames=2)
+        sm.update(self._both_legs_extended())
+        result = sm.update(self._both_legs_extended())
+
+        assert result.rep_count == 0
+        assert sm.phase == DeadBugPhase.READY
+
+    def test_no_pose_preserves_confirmed_rep_until_reset(self):
+        """测试：已确认伸展后短暂丢姿态，回到准备位仍能完成计数"""
+        sm = DeadBugStateMachine(extension_confirm_frames=2, reset_confirm_frames=2)
+        sm.update(self._extended_left())
+        sm.update(self._extended_left())
+        assert sm.phase == DeadBugPhase.EXTENDING
+
+        sm.mark_no_pose()
+        sm.update(self._ready_metrics())
+        result = sm.update(self._ready_metrics())
+
+        assert result.rep_count == 1
+        assert sm.phase == DeadBugPhase.READY