diff --git a/apps/visualizer/src/features/chart/TradingChart.tsx b/apps/visualizer/src/features/chart/TradingChart.tsx
index d3c3abc..44044b2 100644
--- a/apps/visualizer/src/features/chart/TradingChart.tsx
+++ b/apps/visualizer/src/features/chart/TradingChart.tsx
@@ -25,6 +25,8 @@ type Props = {
   ema20?: SeriesPoint[];
   bb20?: { upper: SeriesPoint[]; lower: SeriesPoint[]; mid: SeriesPoint[] };
   showIndicators: boolean;
+  bucketSeconds: number;
+  seriesKey: string;
   fib?: FibRetracement | null;
   fibOpacity?: number;
   fibSelected?: boolean;
@@ -44,11 +46,23 @@ type Props = {
 };
 
 type LinePoint = LineData | WhitespaceData;
+type BuildSample = { t: number; v: number };
 
 function toTime(t: number): UTCTimestamp {
   return t as UTCTimestamp;
 }
 
+function resolveBucketSeconds(bucketSeconds: number, candles: Candle[]): number {
+  if (Number.isFinite(bucketSeconds) && bucketSeconds > 0) return bucketSeconds;
+  if (candles.length >= 2) {
+    const last = candles[candles.length - 1]?.time;
+    const prev = candles[candles.length - 2]?.time;
+    const delta = typeof last === 'number' && typeof prev === 'number' ? last - prev : 0;
+    if (Number.isFinite(delta) && delta > 0) return delta;
+  }
+  return 60;
+}
+
 function samplePriceFromCandles(candles: Candle[]): number | null {
   for (let i = candles.length - 1; i >= 0; i -= 1) {
     const close = candles[i]?.close;
@@ -82,11 +96,10 @@ function toCandleData(candles: Candle[]): CandlestickData[] {
 
 function toVolumeData(candles: Candle[]): HistogramData[] {
   return candles.map((c) => {
-    const up = c.close >= c.open;
     return {
       time: toTime(c.time),
       value: c.volume ?? 0,
-      color: up ? 'rgba(34,197,94,0.35)' : 'rgba(239,68,68,0.35)',
+      color: 'rgba(148,163,184,0.22)',
     };
   });
 }
@@ -103,6 +116,8 @@ export default function TradingChart({
   ema20,
   bb20,
   showIndicators,
+  bucketSeconds,
+  seriesKey,
   fib,
   fibOpacity = 1,
   fibSelected = false,
@@ -124,9 +139,13 @@ export default function TradingChart({
   const onChartCrosshairMoveRef = useRef<Props['onChartCrosshairMove']>(onChartCrosshairMove);
   const onPointerEventRef = useRef<Props['onPointerEvent']>(onPointerEvent);
   const capturedOverlayPointerRef = useRef<number | null>(null);
+  const buildSamplesRef = useRef<Map<number, BuildSample[]>>(new Map());
+  const buildKeyRef = useRef<string | null>(null);
+  const lastBuildCandleStartRef = useRef<number | null>(null);
   const seriesRef = useRef<{
     candles?: ISeriesApi<'Candlestick'>;
     volume?: ISeriesApi<'Histogram'>;
+    build?: ISeriesApi<'Line'>;
     oracle?: ISeriesApi<'Line'>;
     sma20?: ISeriesApi<'Line'>;
     ema20?: ISeriesApi<'Line'>;
@@ -225,7 +244,22 @@ export default function TradingChart({
       color: 'rgba(255,255,255,0.15)',
     });
     volumeSeries.priceScale().applyOptions({
-      scaleMargins: { top: 0.82, bottom: 0 },
+      scaleMargins: { top: 0.88, bottom: 0 },
+    });
+
+    const buildSeries = chart.addSeries(LineSeries, {
+      color: '#60a5fa',
+      lineWidth: 2,
+      priceFormat,
+      priceScaleId: 'build',
+      lastValueVisible: false,
+      priceLineVisible: false,
+      crosshairMarkerVisible: false,
+    });
+    buildSeries.priceScale().applyOptions({
+      scaleMargins: { top: 0.72, bottom: 0.12 },
+      visible: false,
+      borderVisible: false,
     });
 
     const oracleSeries = chart.addSeries(LineSeries, {
@@ -249,6 +283,7 @@ export default function TradingChart({
     seriesRef.current = {
       candles: candleSeries,
       volume: volumeSeries,
+      build: buildSeries,
       oracle: oracleSeries,
       sma20: smaSeries,
       ema20: emaSeries,
@@ -551,7 +586,7 @@ export default function TradingChart({
 
   useEffect(() => {
     const s = seriesRef.current;
-    if (!s.candles || !s.volume) return;
+    if (!s.candles || !s.volume || !s.build) return;
     s.candles.setData(candleData);
     s.volume.setData(volumeData);
     s.oracle?.setData(oracleData);
@@ -561,17 +596,131 @@ export default function TradingChart({
     s.bbLower?.setData(bbLower);
     s.bbMid?.setData(bbMid);
 
+    if (buildKeyRef.current !== seriesKey) {
+      buildSamplesRef.current.clear();
+      buildKeyRef.current = seriesKey;
+      lastBuildCandleStartRef.current = null;
+    }
+
+    const bs = resolveBucketSeconds(bucketSeconds, candles);
+    const eps = 1e-3;
+    const maxPointsPerCandle = 600;
+    const minStep = Math.max(0.5, bs / maxPointsPerCandle);
+    const map = buildSamplesRef.current;
+    const visibleStarts = new Set(candles.map((c) => c.time));
+    for (const start of Array.from(map.keys())) {
+      if (!visibleStarts.has(start)) map.delete(start);
+    }
+
+    const last = candles[candles.length - 1];
+    if (last) {
+      const prevStart = lastBuildCandleStartRef.current;
+      if (prevStart != null && prevStart !== last.time) {
+        const prevCandle = candles.find((c) => c.time === prevStart);
+        if (prevCandle) {
+          const endT = prevStart + bs - eps;
+          const finalDelta = prevCandle.close - prevCandle.open;
+          const list = map.get(prevStart) ?? [];
+          const lastT = list.length ? list[list.length - 1]!.t : -Infinity;
+          if (endT > lastT + eps) {
+            list.push({ t: endT, v: finalDelta });
+          } else if (list.length) {
+            list[list.length - 1] = { t: lastT, v: finalDelta };
+          }
+          map.set(prevStart, list);
+        }
+      }
+
+      const start = last.time;
+      const endT = start + bs - eps;
+      const delta = last.close - last.open;
+      const nowT = Date.now() / 1000;
+      const tClamped = Math.min(endT, Math.max(start + eps, nowT));
+      const list = map.get(start) ?? [];
+      if (list.length) {
+        const lastPt = list[list.length - 1]!;
+        if (tClamped - lastPt.t < minStep) {
+          list[list.length - 1] = { t: tClamped, v: delta };
+        } else {
+          const t = Math.min(endT, Math.max(lastPt.t + eps, tClamped));
+          if (t > lastPt.t) list.push({ t, v: delta });
+        }
+      } else {
+        list.push({ t: tClamped, v: delta });
+      }
+      map.set(start, list);
+      lastBuildCandleStartRef.current = start;
+    }
+
+    const buildRaw: LinePoint[] = [];
+    for (const c of candles) {
+      const list = map.get(c.time);
+      if (!list?.length) continue;
+
+      const startT = c.time + eps;
+      const endT = c.time + bs - eps;
+      if (!(endT > startT)) continue;
+
+      buildRaw.push({ time: toTime(c.time) } as WhitespaceData);
+      buildRaw.push({ time: toTime(startT), value: 0 } as LineData);
+
+      let lastT = startT;
+      for (const p of list) {
+        let t = p.t;
+        if (t <= lastT + eps) t = lastT + eps;
+        if (t >= endT) break;
+        buildRaw.push({ time: toTime(t), value: p.v } as LineData);
+        lastT = t;
+      }
+
+      const finalDelta = c.close - c.open;
+      if (endT > lastT + eps) {
+        buildRaw.push({ time: toTime(endT), value: finalDelta } as LineData);
+      } else if (buildRaw.length) {
+        const prev = buildRaw[buildRaw.length - 1];
+        if ('value' in prev) {
+          buildRaw[buildRaw.length - 1] = { ...prev, value: finalDelta } as LineData;
+        }
+      }
+    }
+
+    const buildColored: LinePoint[] = [];
+    let lastLineIdx: number | null = null;
+    let lastLineVal: number | null = null;
+    for (const p of buildRaw) {
+      if (!('value' in p)) {
+        buildColored.push(p);
+        lastLineIdx = null;
+        lastLineVal = null;
+        continue;
+      }
+
+      if (lastLineIdx != null && lastLineVal != null) {
+        const delta = p.value - lastLineVal;
+        const color = delta > 0 ? '#22c55e' : delta < 0 ? '#ef4444' : '#60a5fa';
+        const prev = buildColored[lastLineIdx] as LineData;
+        buildColored[lastLineIdx] = { ...prev, color };
+      }
+
+      buildColored.push({ time: p.time, value: p.value } as LineData);
+      lastLineIdx = buildColored.length - 1;
+      lastLineVal = p.value;
+    }
+
+    s.build.setData(buildColored);
+
     s.sma20?.applyOptions({ visible: showIndicators });
     s.ema20?.applyOptions({ visible: showIndicators });
     s.bbUpper?.applyOptions({ visible: showIndicators });
     s.bbLower?.applyOptions({ visible: showIndicators });
     s.bbMid?.applyOptions({ visible: showIndicators });
-  }, [candleData, volumeData, oracleData, smaData, emaData, bbUpper, bbLower, bbMid, showIndicators]);
+  }, [candleData, volumeData, oracleData, smaData, emaData, bbUpper, bbLower, bbMid, showIndicators, candles, bucketSeconds, seriesKey]);
 
   useEffect(() => {
     const s = seriesRef.current;
     if (!s.candles) return;
     s.candles.applyOptions({ priceFormat });
+    s.build?.applyOptions({ priceFormat });
     s.oracle?.applyOptions({ priceFormat });
     s.sma20?.applyOptions({ priceFormat });
     s.ema20?.applyOptions({ priceFormat });