Show 30-minute candles on the last-24-hours chart

tests/test_health.py

@@ -107,3 +107,22 @@ def test_version_endpoint(monkeypatch):
 
     assert response.status_code == 200
     assert response.json() == {"version": "abc1234"}
+
+
+def test_24_hour_chart_uses_half_hour_candles():
+    response = TestClient(main.app).get("/")
+    assert "24h Candles (30m)" in response.text
+    assert "initChart('chart-hour', '/api/kraken-half-hour', 5 * 60 * 1000, updateMidnightPrice)" in response.text
+    assert "initChart('chart-minute', '/api/kraken-minute', 60 * 1000)" in response.text
+
+
+def test_half_hour_proxy_preserves_candles_and_upstream_errors(monkeypatch):
+    for status, payload in [(200, [{"ts": 1800, "open": "10", "high": "12", "low": "9", "close": "11"}]), (503, {"error": "database unavailable"})]:
+        request = httpx.Request("GET", "http://btcdata.test/api/kraken-half-hour")
+        client = StubAsyncClient(response=httpx.Response(status, json=payload, request=request))
+        monkeypatch.setattr(main, "BTCDATA_URL", "http://btcdata.test")
+        monkeypatch.setattr(main.httpx, "AsyncClient", lambda: client)
+        response = TestClient(main.app).get("/api/kraken-half-hour")
+        assert response.status_code == status
+        assert response.json() == payload
+        assert client.requested_url == "http://btcdata.test/api/kraken-half-hour"