diff --git a/frontend/src/utils/ChartManager.ts b/frontend/src/utils/ChartManager.ts
index c3a8d38..c766514 100644
--- a/frontend/src/utils/ChartManager.ts
+++ b/frontend/src/utils/ChartManager.ts
@@ -1368,7 +1368,7 @@ export class ChartManager {
     return out;
   }
 
-  /** 특정 바 인덱스에서 Donchian 중선을 계산 */
+  /** 특정 바 인덱스에서 Donchian 중선 (전환선·기준선·선행스팬B 공통) */
   private _donchianAt(idx: number, period: number): number | null {
     const start = idx - period + 1;
     if (start < 0) return null;
@@ -1378,35 +1378,33 @@ export class ChartManager {
       if (this.rawBars[i].low  < lo) lo = this.rawBars[i].low;
     }
     return (hi + lo) / 2;
-  }   
-  
-  /** 구름 데이터 빌드: 과거(역사 데이터) + 미래 26봉 포함 */
+  }
+
+  /**
+   * 일목 구름: rawBars만으로 계산 (vite dev / 프로덕션 번들 동일 결과).
+   * lightweight-charts-indicators 의 plot3·plot4는 서버 프로덕션 빌드에서
+   * spanA===spanB 로 붕괴할 수 있어 사용하지 않는다.
+   */
   private _buildIchimokuCloudData(
-    _spanAPlot: PlotData,
-    _spanBPlot: PlotData,
-    convPlot:   PlotData,
-    basePlot:   PlotData,
+    conversionPeriods: number,
+    basePeriods: number,
     displacement: number,
     laggingPeriod: number,
   ): IchimokuCloudPoint[] {
-    // 라이브러리의 plot3/plot4(SpanA/SpanB)는 프로덕션 빌드에서
-    // 동일한 값을 반환하는 버그가 있으므로, convPlot(전환선)/basePlot(기준선)과
-    // rawBars 기반 _donchianAt으로 직접 재계산한다.
     const N = this.rawBars.length;
     const historical: IchimokuCloudPoint[] = [];
 
-    for (let i = displacement - 1; i < N; i++) {
-      const srcIdx = i - (displacement - 1);
-      const conv = convPlot[srcIdx]?.value;
-      const base = basePlot[srcIdx]?.value;
-      if (conv == null || isNaN(conv) || base == null || isNaN(base)) continue;
-      const spanA = (conv + base) / 2;
+    for (let i = displacement; i < N; i++) {
+      const srcIdx = i - displacement;
+      const tenkan = this._donchianAt(srcIdx, conversionPeriods);
+      const kijun  = this._donchianAt(srcIdx, basePeriods);
+      if (tenkan == null || kijun == null) continue;
+      const spanA = (tenkan + kijun) / 2;
       const spanB = this._donchianAt(srcIdx, laggingPeriod);
-      if (spanB === null) continue;
+      if (spanB == null) continue;
       historical.push({ time: this.rawBars[i].time, spanA, spanB });
     }
 
-    // 미래 구름
     if (N < 2) return historical;
     const interval = this.rawBars[N - 1].time - this.rawBars[N - 2].time;
     const lastTime  = this.rawBars[N - 1].time;
@@ -1415,12 +1413,12 @@ export class ChartManager {
     for (let k = 1; k <= displacement; k++) {
       const srcIdx = N - displacement - 1 + k;
       if (srcIdx < 0 || srcIdx >= N) continue;
-      const conv = convPlot[srcIdx]?.value;
-      const base = basePlot[srcIdx]?.value;
-      if (conv == null || isNaN(conv) || base == null || isNaN(base)) continue;
-      const spanA = (conv + base) / 2;
+      const tenkan = this._donchianAt(srcIdx, conversionPeriods);
+      const kijun  = this._donchianAt(srcIdx, basePeriods);
+      if (tenkan == null || kijun == null) continue;
+      const spanA = (tenkan + kijun) / 2;
       const spanB = this._donchianAt(srcIdx, laggingPeriod);
-      if (spanB === null) continue;
+      if (spanB == null) continue;
       future.push({ time: lastTime + k * interval, spanA, spanB });
     }
     return [...historical, ...future];
@@ -1782,17 +1780,13 @@ export class ChartManager {
       return;
     }
 
-    const spanAPlot = plots['plot3'] as PlotData | undefined;
-    const spanBPlot = plots['plot4'] as PlotData | undefined;
-    const convPlot  = plots['plot0'] as PlotData ?? [];
-    const basePlot  = plots['plot1'] as PlotData ?? [];
-    if (!spanAPlot || !spanBPlot) return;
-
     const { senkou: displacement } = resolveIchimokuDisplacements(config.params);
+    const conversionPeriods = (config.params?.conversionPeriods as number) ?? 9;
+    const basePeriods = (config.params?.basePeriods as number) ?? 26;
     const laggingPeriod = (config.params?.laggingSpan2Periods as number) ?? 52;
 
     const cloud = this._buildIchimokuCloudData(
-      spanAPlot, spanBPlot, convPlot, basePlot, displacement, laggingPeriod,
+      conversionPeriods, basePeriods, displacement, laggingPeriod,
     );
     plugin.setCloudData(cloud.length >= 2 ? cloud : []);
   }