# 离线只读验证：不访问网络、不操作设备，只读取同目录合成输入。
import json, math, struct, statistics
from pathlib import Path
def med(seq): return [None if i<2 else statistics.median(seq[i-2:i+1]) for i in range(len(seq))]
def check(d):
 a=med(d['spike']); b=med(d['step'])
 delay=b.index(20)-d['step'].index(20)
 return dict(spike=a,step=b,step_delay_samples=delay)

if __name__=='__main__':
 fixture=json.loads(Path(__file__).with_name('fixture.json').read_text(encoding='utf-8'))
 actual=check(fixture['input'])
 assert actual==fixture['expected'], {'实际':actual,'预期':fixture['expected']}
 print(json.dumps({'状态':'通过','实际':actual,'边界':'仅离线合成样例，现场未测'},ensure_ascii=False))