fix(network): add offline cooldown guard for remote metadata requests

tests/services/test_connectivity_guard.py

@@ -0,0 +1,74 @@
+import asyncio
+import errno
+from datetime import datetime, timedelta
+
+import pytest
+
+from py.services.connectivity_guard import (
+    OFFLINE_COOLDOWN_ERROR,
+    ConnectivityGuard,
+)
+from py.services.downloader import Downloader
+
+
+@pytest.fixture(autouse=True)
+def reset_connectivity_guard_singleton():
+    ConnectivityGuard._instance = None
+    yield
+    ConnectivityGuard._instance = None
+
+
+async def test_connectivity_guard_enters_cooldown_after_threshold():
+    guard = await ConnectivityGuard.get_instance()
+
+    assert guard.online is True
+    assert guard.should_block_request() is False
+
+    guard.register_network_failure(OSError(errno.ENETUNREACH, "unreachable"))
+    guard.register_network_failure(asyncio.TimeoutError("timeout"))
+
+    assert guard.should_block_request() is False
+    assert guard.failure_count == 2
+
+    guard.register_network_failure(ConnectionRefusedError("refused"))
+
+    assert guard.online is False
+    assert guard.failure_count == 3
+    assert guard.should_block_request() is True
+    assert guard.cooldown_remaining_seconds() > 0
+
+
+async def test_connectivity_guard_recovers_after_success():
+    guard = await ConnectivityGuard.get_instance()
+    guard.online = False
+    guard.failure_count = 5
+    guard.cooldown_until = datetime.now() + timedelta(seconds=90)
+
+    guard.register_success()
+
+    assert guard.online is True
+    assert guard.failure_count == 0
+    assert guard.cooldown_until is None
+    assert guard.should_block_request() is False
+
+
+async def test_downloader_short_circuits_all_request_helpers_during_cooldown():
+    guard = await ConnectivityGuard.get_instance()
+    guard.cooldown_until = datetime.now() + timedelta(seconds=30)
+    guard.online = False
+    guard.failure_count = 3
+
+    downloader = Downloader()
+
+    ok, payload = await downloader.make_request("GET", "https://example.invalid")
+    assert ok is False
+    assert payload == OFFLINE_COOLDOWN_ERROR
+
+    ok, payload, headers = await downloader.download_to_memory("https://example.invalid")
+    assert ok is False
+    assert payload == OFFLINE_COOLDOWN_ERROR
+    assert headers is None
+
+    ok, payload = await downloader.get_response_headers("https://example.invalid")
+    assert ok is False
+    assert payload == OFFLINE_COOLDOWN_ERROR