fix: return retryable event stream upstream failures (#67)

tests/test_event_stream.py

@@ -74,6 +74,22 @@ async def test_event_stream_returns_retryable_response_when_gitea_exceeds_deadli
     assert cancelled.is_set()
 
 
+@pytest.mark.anyio
+async def test_event_stream_returns_retryable_response_when_gitea_request_fails(monkeypatch):
+    async def failing_activity_events():
+        raise ConnectionError("connection refused")
+
+    monkeypatch.setattr(main, "activity_events", failing_activity_events)
+
+    response = await main.event_stream()
+
+    assert response.status_code == 503
+    assert response.headers["retry-after"] == "5"
+    assert json.loads(response.body) == {
+        "error": "Gitea event stream is temporarily unavailable"
+    }
+
+
 @pytest.mark.anyio
 async def test_activity_events_fetches_feed_for_authenticated_user(monkeypatch):
     paths = []