fix: enhance caching mechanism and improve type hints in DoH and workflow modules

tests/test_doh_helper.py

@@ -0,0 +1,41 @@
+import socket
+
+from app.helper import doh
+
+
+def test_enable_doh_reuses_cached_host_resolution(monkeypatch):
+    """
+    同一 DoH 域名第二次解析应命中缓存，避免重复请求远端解析器。
+    """
+    query_calls = []
+    resolved_hosts = []
+
+    def fake_query(resolver: str, host: str) -> str:
+        query_calls.append((resolver, host))
+        return "203.0.113.7"
+
+    def fake_getaddrinfo(host: str, *args, **kwargs):
+        resolved_hosts.append(host)
+        return [(socket.AF_INET, socket.SOCK_STREAM, 0, "", (host, 0))]
+
+    monkeypatch.setattr(doh.settings, "DOH_DOMAINS", "example.com")
+    monkeypatch.setattr(doh.settings, "DOH_RESOLVERS", "resolver.test")
+    monkeypatch.setattr(doh, "_doh_query", fake_query)
+    monkeypatch.setattr(doh, "_orig_getaddrinfo", fake_getaddrinfo)
+
+    original_getaddrinfo = socket.getaddrinfo
+    with doh._doh_lock:
+        doh._doh_cache.clear()
+
+    try:
+        doh.enable_doh(True)
+
+        socket.getaddrinfo("example.com", None)
+        socket.getaddrinfo("example.com", None)
+    finally:
+        socket.getaddrinfo = original_getaddrinfo
+        with doh._doh_lock:
+            doh._doh_cache.clear()
+
+    assert query_calls == [("resolver.test", "example.com")]
+    assert resolved_hosts == ["203.0.113.7", "203.0.113.7"]