test(host_agent): agent POST, backoff, and main loop

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

tests/plugins/host_agent/test_agent_build_payload.py

@@ -53,3 +53,65 @@ def test_build_payload_wraps_samples():
     assert payload["metadata"] == metadata
     assert len(payload["samples"]) == 1
     assert payload["samples"][0]["cpu_pct"] == 5.0
+
+
+import urllib.error
+from unittest.mock import MagicMock, patch
+
+
+def test_post_payload_success():
+    from plugins.host_agent import agent as a
+    captured = {}
+
+    class FakeResp:
+        status = 200
+        def __enter__(self): return self
+        def __exit__(self, *a): return False
+        def read(self): return b'{"ok":true}'
+
+    def fake_urlopen(req, timeout=10):
+        captured["url"] = req.full_url
+        captured["headers"] = dict(req.header_items())
+        captured["body"] = req.data
+        return FakeResp()
+
+    with patch.object(a.urllib.request, "urlopen", side_effect=fake_urlopen):
+        ok, status = a.post_payload("https://x", "tok", {"hello": "world"})
+    assert ok is True
+    assert status == 200
+    assert captured["url"] == "https://x/plugins/host_agent/ingest"
+    assert captured["headers"]["Authorization"] == "Bearer tok"
+
+
+def test_post_payload_http_error_returns_status():
+    from plugins.host_agent import agent as a
+
+    def raise_401(req, timeout=10):
+        raise urllib.error.HTTPError(req.full_url, 401, "unauthorized", {}, None)
+
+    with patch.object(a.urllib.request, "urlopen", side_effect=raise_401):
+        ok, status = a.post_payload("https://x", "tok", {})
+    assert ok is False
+    assert status == 401
+
+
+def test_post_payload_network_error_returns_none_status():
+    from plugins.host_agent import agent as a
+
+    def raise_url(req, timeout=10):
+        raise urllib.error.URLError("conn refused")
+
+    with patch.object(a.urllib.request, "urlopen", side_effect=raise_url):
+        ok, status = a.post_payload("https://x", "tok", {})
+    assert ok is False
+    assert status is None
+
+
+def test_backoff_schedule():
+    from plugins.host_agent.agent import next_backoff
+    assert next_backoff(0) == 30
+    assert next_backoff(30) == 60
+    assert next_backoff(60) == 120
+    assert next_backoff(120) == 240
+    assert next_backoff(240) == 300  # capped
+    assert next_backoff(300) == 300