Simplify and caption

src/lib/net.py

@@ -0,0 +1,19 @@
+#!/usr/bin/env python3
+import time
+from urllib.error import URLError
+from urllib.request import Request, urlopen
+
+RETRY_DELAYS = (3, 10)
+
+
+def urlopen_with_retry(req: Request, timeout: int = 30):
+    """urlopen wrapper that retries transient network failures."""
+    last_err: Exception | None = None
+    for attempt in range(len(RETRY_DELAYS) + 1):
+        try:
+            return urlopen(req, timeout=timeout)
+        except (URLError, TimeoutError) as e:
+            last_err = e
+            if attempt < len(RETRY_DELAYS):
+                time.sleep(RETRY_DELAYS[attempt])
+    raise last_err