库存监控代理 IP：补货监控、到货提醒脚本用的固定出口

# pip install requests
import os
import time
import requests

PROXY = os.environ["PROXY_URL"]  # static datacenter IP from My assets: http://USER:PASS@HOST:PORT
PROXIES = {"http": PROXY, "https": PROXY}
URL = "https://store.example.com/products/limited-sneaker.js"  # Shopify product JSON

session = requests.Session()
etag, last = None, None

for _ in range(3):  # in production, let your scheduler run each check
    headers = {"If-None-Match": etag} if etag else {}
    try:
        r = session.get(URL, headers=headers, proxies=PROXIES, timeout=20)
        status = r.status_code
    except requests.RequestException as exc:  # proxy refused (407), timeout or connection error
        status = type(exc).__name__
    if status == 304:
        print("unchanged (304, no body downloaded)")
    elif status == 200:
        etag = r.headers.get("ETag")
        in_stock = [v["title"] for v in r.json()["variants"] if v["available"]]
        if in_stock != last:
            print("in stock:", in_stock or "none")
            last = in_stock
    else:
        print("unknown, keeping last state:", status)  # never turn an error into "sold out"
    time.sleep(30)