日志显示调用已完成并扣费，客户端却收不到响应，怎么排查？

import json, os, time, urllib.request

body = json.dumps({
    "model": "gpt-image-2-vip",
    "prompt": "a watercolor mountain village",
    "size": "2048x2048",
}).encode()

req = urllib.request.Request(
    "https://api.apiyi.com/v1/images/generations",
    data=body,
    headers={
        "Authorization": "Bearer " + os.environ["APIYI_API_KEY"],
        "Content-Type": "application/json",
    },
)

t0 = time.monotonic()
resp = urllib.request.urlopen(req, timeout=900)
ttfb = time.monotonic() - t0            # 响应头到达 ≈ 上游生成结束

chunks, total, last = [], 0, time.monotonic()
while True:
    buf = resp.read(65536)
    now = time.monotonic()
    if not buf:
        break
    total += len(buf)
    chunks.append((round(now - t0, 3), round(now - last, 3), total))
    last = now
t_end = time.monotonic() - t0

transfer = t_end - ttfb
max_gap = max((gap for _, gap, _ in chunks), default=0)
p99_at = next((t for t, _, cum in chunks if cum >= total * 0.99), ttfb)

print(json.dumps({
    "ttfb_s": round(ttfb, 2),                 # ≈ 控制台日志的用时
    "transfer_s": round(transfer, 2),         # 下行回流
    "total_s": round(t_end, 2),               # 你的体感耗时
    "body_bytes": total,
    "down_KBps": round(total / 1024 / transfer, 1) if transfer > 0.001 else None,
    "max_gap_s": max_gap,                     # 块间最大停顿
    "tail_99_s": round(t_end - p99_at, 2),    # 最后 1% 的字节花了多久
}, ensure_ascii=False))