feat(history): align fields quality and exports

vehicle-data-platform/apps/api/internal/platform/service_test.go

@@ -580,6 +580,9 @@ func TestHistoryExportRunsAsControlledAsyncJob(t *testing.T) {
 			if len(body) < 3 || string(body[:3]) != "\xEF\xBB\xBF" {
 				t.Fatalf("CSV should include UTF-8 BOM")
 			}
+			if !strings.Contains(string(body), "数据质量,质量原因,证据ID") {
+				t.Fatalf("CSV should explain platform quality: %q", body[:min(len(body), 512)])
+			}
 			return
 		}
 		time.Sleep(10 * time.Millisecond)
@@ -671,6 +674,39 @@ func TestRawMetricMetadataKeepsProtocolAndUnit(t *testing.T) {
 	}
 }
 
+func TestHistoryQualityReasonsExplainLocationRawAndMileageWarnings(t *testing.T) {
+	quality, reason := historyLocationQuality(HistoryLocationRow{Longitude: 0, Latitude: 0, SpeedKmh: 30, DeviceTime: "2026-07-14 09:29:58", ServerTime: "2026-07-14 09:29:59"})
+	if quality != "warning" || !strings.Contains(reason, "坐标") {
+		t.Fatalf("invalid coordinate should be explained: %s %s", quality, reason)
+	}
+	quality, reason = historyRawQuality(RawFrameRow{DeviceTime: "2026-07-14 09:29:58", ServerTime: "2026-07-14 09:29:59", ParseStatus: "failed", ParseError: "checksum"})
+	if quality != "warning" || !strings.Contains(reason, "checksum") {
+		t.Fatalf("parse failure should retain detail: %s %s", quality, reason)
+	}
+	quality, reason = historyMileageQuality(DailyMileageRow{StartMileageKm: 100, EndMileageKm: 130, DailyMileageKm: 12})
+	if quality != "warning" || !strings.Contains(reason, "不一致") {
+		t.Fatalf("mileage mismatch should be explained: %s %s", quality, reason)
+	}
+}
+
+func TestMergeDiscoveredRawMetricsScansFetchedScope(t *testing.T) {
+	rows := []HistoryDataRow{
+		{Values: map[string]any{"frameType": "realtime"}},
+		{Values: map[string]any{"gb32960.vehicle.soc_percent": 88}},
+	}
+	columns := mergeDiscoveredRawMetrics(historyRawMetrics(), rows)
+	found := false
+	for _, column := range columns {
+		if column.Key == "gb32960.vehicle.soc_percent" {
+			found = true
+			break
+		}
+	}
+	if !found {
+		t.Fatalf("discovered field outside the visible page should remain selectable: %+v", columns)
+	}
+}
+
 func TestBuildLatestTelemetryResponseUsesCatalogAndNewestSourceEvidence(t *testing.T) {
 	now := time.Date(2026, 7, 14, 9, 30, 0, 0, time.FixedZone("Asia/Shanghai", 8*60*60))
 	definitions := []MetricDefinition{