apps/visualizer/src/features/chart/TradingChart.tsx

@@ -1,13 +1,18 @@
-import { useEffect, useMemo, useRef } from 'react';
+import { useEffect, useMemo, useRef, useState } from 'react';
 import {
   CandlestickSeries,
   ColorType,
   CrosshairMode,
   HistogramSeries,
+  type IPrimitivePaneRenderer,
+  type IPrimitivePaneView,
   type IChartApi,
   type ISeriesApi,
+  type ISeriesPrimitive,
   LineStyle,
   LineSeries,
+  type SeriesAttachedParameter,
+  type Time,
   createChart,
   type UTCTimestamp,
   type CandlestickData,
@@ -28,6 +33,15 @@ type Props = {
   showBuild: boolean;
   bucketSeconds: number;
   seriesKey: string;
+  priceLines?: Array<{
+    id: string;
+    title: string;
+    price: number | null;
+    color: string;
+    lineWidth?: number;
+    lineStyle?: LineStyle;
+    axisLabelVisible?: boolean;
+  }>;
   fib?: FibRetracement | null;
   fibOpacity?: number;
   fibSelected?: boolean;
@@ -49,6 +63,13 @@ type Props = {
 type LinePoint = LineData | WhitespaceData;
 type BuildSample = { t: number; v: number };
 
+const BUILD_UP_COLOR = '#22c55e';
+const BUILD_DOWN_COLOR = '#ef4444';
+const BUILD_FLAT_COLOR = '#60a5fa';
+const BUILD_UP_SLICE = 'rgba(34,197,94,0.70)';
+const BUILD_DOWN_SLICE = 'rgba(239,68,68,0.70)';
+const BUILD_FLAT_SLICE = 'rgba(96,165,250,0.70)';
+
 function toTime(t: number): UTCTimestamp {
   return t as UTCTimestamp;
 }
@@ -107,7 +128,361 @@ function toVolumeData(candles: Candle[]): HistogramData[] {
 
 function toLineSeries(points: SeriesPoint[] | undefined): LinePoint[] {
   if (!points?.length) return [];
-  return points.map((p) => (p.value == null ? ({ time: toTime(p.time) } as WhitespaceData) : { time: toTime(p.time), value: p.value }));
+  return points.map((p) =>
+    p.value == null ? ({ time: toTime(p.time) } as WhitespaceData) : { time: toTime(p.time), value: p.value }
+  );
+}
+
+function colorForDelta(delta: number): string {
+  if (delta > 0) return BUILD_UP_COLOR;
+  if (delta < 0) return BUILD_DOWN_COLOR;
+  return BUILD_FLAT_COLOR;
+}
+
+function sliceColorForDelta(delta: number): string {
+  if (delta > 0) return BUILD_UP_SLICE;
+  if (delta < 0) return BUILD_DOWN_SLICE;
+  return BUILD_FLAT_SLICE;
+}
+
+type SliceDir = -1 | 0 | 1;
+
+function dirForDelta(delta: number): SliceDir {
+  if (delta > 0) return 1;
+  if (delta < 0) return -1;
+  return 0;
+}
+
+function buildDeltaSeriesForCandle(candle: Candle, bs: number, samples: BuildSample[] | undefined): LinePoint[] {
+  const eps = 1e-3;
+  const startT = candle.time + eps;
+  const endT = candle.time + bs - eps;
+  if (!(endT > startT)) return [];
+
+  const points: BuildSample[] = [{ t: startT, v: 0 }];
+  let lastT = startT;
+  for (const p of samples || []) {
+    let t = p.t;
+    if (t <= lastT + eps) t = lastT + eps;
+    if (t >= endT) break;
+    points.push({ t, v: p.v });
+    lastT = t;
+  }
+
+  const finalDelta = candle.close - candle.open;
+  if (endT > lastT + eps) {
+    points.push({ t: endT, v: finalDelta });
+  } else if (points.length) {
+    points[points.length - 1] = { ...points[points.length - 1]!, v: finalDelta };
+  }
+
+  const out: LinePoint[] = [{ time: toTime(candle.time) } as WhitespaceData];
+  out.push({ time: toTime(points[0]!.t), value: points[0]!.v } as LineData);
+
+  let lastLineIdx = out.length - 1;
+  let lastVal = points[0]!.v;
+  for (let i = 1; i < points.length; i += 1) {
+    const v = points[i]!.v;
+    const prev = out[lastLineIdx] as LineData;
+    out[lastLineIdx] = { ...prev, color: colorForDelta(v - lastVal) } as LineData;
+    out.push({ time: toTime(points[i]!.t), value: v } as LineData);
+    lastLineIdx = out.length - 1;
+    lastVal = v;
+  }
+  return out;
+}
+
+type BuildSlicesState = {
+  enabled: boolean;
+  candles: Candle[];
+  bucketSeconds: number;
+  samples: Map<number, BuildSample[]>;
+  series: ISeriesApi<'Histogram', Time> | null;
+  chart: SeriesAttachedParameter<Time>['chart'] | null;
+};
+
+class BuildSlicesPaneRenderer implements IPrimitivePaneRenderer {
+  private readonly _getState: () => BuildSlicesState;
+
+  constructor(getState: () => BuildSlicesState) {
+    this._getState = getState;
+  }
+
+  draw(target: any) {
+    const { enabled, candles, bucketSeconds, samples, series, chart } = this._getState();
+    if (!enabled) return;
+    if (!candles.length || !series || !chart) return;
+
+    const bs = resolveBucketSeconds(bucketSeconds, candles);
+    const lastCandleTime = candles[candles.length - 1]?.time ?? null;
+
+    const yBase = series.priceToCoordinate(0);
+    if (yBase == null) return;
+
+    const xs = candles.map((c) => chart.timeScale().timeToCoordinate(toTime(c.time)));
+
+    target.useBitmapCoordinateSpace(({ context, bitmapSize, horizontalPixelRatio, verticalPixelRatio }: any) => {
+      const yBottomPx = Math.round(yBase * verticalPixelRatio);
+      const lastIdx = xs.length - 1;
+
+      for (let i = 0; i < candles.length; i += 1) {
+        const x = xs[i];
+        if (x == null) continue;
+        if (!Number.isFinite(x)) continue;
+
+        const c = candles[i]!;
+
+        const start = c.time;
+        const end = start + bs;
+        const isCurrent = lastCandleTime != null && c.time === lastCandleTime;
+        const now = Date.now() / 1000;
+        const progressT = isCurrent ? Math.min(end, Math.max(start, now)) : end;
+
+        let spacing = 0;
+        const prevX = i > 0 ? xs[i - 1] : null;
+        const nextX = i < lastIdx ? xs[i + 1] : null;
+        if (prevX != null && Number.isFinite(prevX)) spacing = x - prevX;
+        if (nextX != null && Number.isFinite(nextX)) {
+          const s2 = nextX - x;
+          spacing = spacing > 0 ? Math.min(spacing, s2) : s2;
+        }
+        if (!(spacing > 0)) spacing = 6;
+
+        const barWidthCss = Math.max(1, spacing * 0.9);
+        const barWidthPx = Math.max(1, Math.round(barWidthCss * horizontalPixelRatio));
+        const xCenterPx = Math.round(x * horizontalPixelRatio);
+        const xLeftPx = Math.round(xCenterPx - barWidthPx / 2);
+
+        const volumeValue = typeof c.volume === 'number' && Number.isFinite(c.volume) ? c.volume : 0;
+        if (!(volumeValue > 0)) continue;
+        const yTop = series.priceToCoordinate(volumeValue);
+        if (yTop == null) continue;
+        const yTopPx = Math.round(yTop * verticalPixelRatio);
+        if (!(yBottomPx > yTopPx)) continue;
+        const barHeightPx = yBottomPx - yTopPx;
+
+        const x0 = Math.max(0, Math.min(bitmapSize.width, xLeftPx));
+        const x1 = Math.max(0, Math.min(bitmapSize.width, xLeftPx + barWidthPx));
+        const w = x1 - x0;
+        if (!(w > 0)) continue;
+
+        // Prefer server-provided `flowRows`: brick-by-brick direction per time slice inside the candle.
+        // Fallback to `flow` (3 shares) or net candle direction.
+        const rowsFromApi = Array.isArray((c as any).flowRows) ? ((c as any).flowRows as any[]) : null;
+        const rowDirs = rowsFromApi?.length ? rowsFromApi : null;
+
+        if (rowDirs) {
+          const rows = Math.max(1, rowDirs.length);
+          const progressRows = Math.max(0, Math.min(rows, Math.ceil(((progressT - start) / bs) * rows)));
+          const movesFromApi = Array.isArray((c as any).flowMoves) ? ((c as any).flowMoves as any[]) : null;
+          const rowMoves = movesFromApi && movesFromApi.length === rows ? movesFromApi : null;
+          let maxMove = 0;
+          if (rowMoves) {
+            for (let r = 0; r < progressRows; r += 1) {
+              const v = Number(rowMoves[r]);
+              if (Number.isFinite(v) && v > maxMove) maxMove = v;
+            }
+          }
+
+          const sepPx = 1; // black separator line between steps
+          const sepColor = 'rgba(0,0,0,0.75)';
+
+          // Blue (flat) bricks have a constant pixel height (unit).
+          // Up/down bricks are scaled by |Δ| in their dt.
+          const minNonFlatPx = 1;
+          let unitFlatPx = 2;
+
+          let flatCount = 0;
+          let nonFlatCount = 0;
+          for (let r = 0; r < progressRows; r += 1) {
+            const dirRaw = rowDirs[r];
+            const dir = dirRaw > 0 ? 1 : dirRaw < 0 ? -1 : 0;
+            if (dir === 0) flatCount += 1;
+            else nonFlatCount += 1;
+          }
+
+          const sepTotal = Math.max(0, progressRows - 1) * sepPx;
+          if (flatCount > 0) {
+            const maxUnit = Math.floor((barHeightPx - sepTotal - nonFlatCount * minNonFlatPx) / flatCount);
+            unitFlatPx = Math.max(1, Math.min(unitFlatPx, maxUnit));
+          } else {
+            unitFlatPx = 0;
+          }
+
+          let nonFlatAvailable = barHeightPx - sepTotal - flatCount * unitFlatPx;
+          if (!Number.isFinite(nonFlatAvailable) || nonFlatAvailable < 0) nonFlatAvailable = 0;
+
+          const baseNonFlat = nonFlatCount * minNonFlatPx;
+          let extra = nonFlatAvailable - baseNonFlat;
+          if (!Number.isFinite(extra) || extra < 0) extra = 0;
+
+          let sumMove = 0;
+          if (nonFlatCount > 0) {
+            for (let r = 0; r < progressRows; r += 1) {
+              const dirRaw = rowDirs[r];
+              const dir = dirRaw > 0 ? 1 : dirRaw < 0 ? -1 : 0;
+              if (dir === 0) continue;
+              const mvRaw = rowMoves ? Number(rowMoves[r]) : 0;
+              const mv = Number.isFinite(mvRaw) ? Math.max(0, mvRaw) : 0;
+              sumMove += mv;
+            }
+          }
+
+          if (!(flatCount + nonFlatCount > 0) || barHeightPx <= sepTotal) {
+            continue;
+          }
+
+          // Stack bricks bottom-up (earliest slices at the bottom).
+          let usedExtra = 0;
+          let nonFlatSeen = 0;
+          let y = yBottomPx;
+          for (let r = 0; r < progressRows; r += 1) {
+            const dirRaw = rowDirs[r];
+            const dir = dirRaw > 0 ? 1 : dirRaw < 0 ? -1 : 0;
+            const isLast = r === progressRows - 1;
+
+            let h = 0;
+            if (dir === 0) {
+              h = unitFlatPx;
+            } else {
+              nonFlatSeen += 1;
+              const mvRaw = rowMoves ? Number(rowMoves[r]) : 0;
+              const mv = Number.isFinite(mvRaw) ? Math.max(0, mvRaw) : 0;
+              const share = sumMove > 0 ? mv / sumMove : 1 / nonFlatCount;
+              const wantExtra = Math.floor(extra * share);
+              const isLastNonFlat = nonFlatSeen === nonFlatCount;
+              const add = isLastNonFlat ? Math.max(0, extra - usedExtra) : Math.max(0, wantExtra);
+              usedExtra += add;
+              h = minNonFlatPx + add;
+            }
+
+            if (h <= 0) continue;
+            y -= h;
+            context.fillStyle = sliceColorForDelta(dir);
+            context.fillRect(x0, y, w, h);
+
+            if (!isLast) {
+              y -= sepPx;
+              context.fillStyle = sepColor;
+              context.fillRect(x0, y, w, sepPx);
+            }
+          }
+          continue;
+        }
+
+        const f: any = (c as any).flow;
+        let upShare = typeof f?.up === 'number' ? f.up : Number(f?.up);
+        let downShare = typeof f?.down === 'number' ? f.down : Number(f?.down);
+        let flatShare = typeof f?.flat === 'number' ? f.flat : Number(f?.flat);
+
+        if (!Number.isFinite(upShare)) upShare = 0;
+        if (!Number.isFinite(downShare)) downShare = 0;
+        if (!Number.isFinite(flatShare)) flatShare = 0;
+        upShare = Math.max(0, upShare);
+        downShare = Math.max(0, downShare);
+        flatShare = Math.max(0, flatShare);
+
+        let sum = upShare + downShare + flatShare;
+        if (!(sum > 0)) {
+          const overallDir = dirForDelta(c.close - c.open);
+          upShare = overallDir > 0 ? 1 : 0;
+          downShare = overallDir < 0 ? 1 : 0;
+          flatShare = overallDir === 0 ? 1 : 0;
+          sum = 1;
+        }
+
+        upShare /= sum;
+        downShare /= sum;
+        flatShare /= sum;
+
+        const downH = Math.floor(barHeightPx * downShare);
+        const flatH = Math.floor(barHeightPx * flatShare);
+        const upH = Math.max(0, barHeightPx - downH - flatH);
+
+        let y = yBottomPx;
+
+        if (downH > 0) {
+          context.fillStyle = sliceColorForDelta(-1);
+          context.fillRect(x0, y - downH, w, downH);
+          y -= downH;
+        }
+        if (flatH > 0) {
+          context.fillStyle = sliceColorForDelta(0);
+          context.fillRect(x0, y - flatH, w, flatH);
+          y -= flatH;
+        }
+        if (upH > 0) {
+          context.fillStyle = sliceColorForDelta(1);
+          context.fillRect(x0, y - upH, w, upH);
+        }
+      }
+    });
+  }
+}
+
+class BuildSlicesPaneView implements IPrimitivePaneView {
+  private readonly _renderer: BuildSlicesPaneRenderer;
+
+  constructor(getState: () => BuildSlicesState) {
+    this._renderer = new BuildSlicesPaneRenderer(getState);
+  }
+
+  zOrder() {
+    return 'top';
+  }
+
+  renderer() {
+    return this._renderer;
+  }
+}
+
+class BuildSlicesPrimitive implements ISeriesPrimitive<Time> {
+  private _param: SeriesAttachedParameter<Time> | null = null;
+  private _series: ISeriesApi<'Histogram', Time> | null = null;
+  private _enabled = true;
+  private _candles: Candle[] = [];
+  private _bucketSeconds = 0;
+  private _samples: Map<number, BuildSample[]> = new Map();
+  private readonly _paneView: BuildSlicesPaneView;
+  private readonly _paneViews: readonly IPrimitivePaneView[];
+
+  constructor() {
+    this._paneView = new BuildSlicesPaneView(() => ({
+      enabled: this._enabled,
+      candles: this._candles,
+      bucketSeconds: this._bucketSeconds,
+      samples: this._samples,
+      series: this._series,
+      chart: this._param?.chart ?? null,
+    }));
+    this._paneViews = [this._paneView];
+  }
+
+  attached(param: SeriesAttachedParameter<Time>) {
+    this._param = param;
+    this._series = param.series as ISeriesApi<'Histogram', Time>;
+  }
+
+  detached() {
+    this._param = null;
+    this._series = null;
+  }
+
+  paneViews() {
+    return this._paneViews;
+  }
+
+  setEnabled(next: boolean) {
+    this._enabled = Boolean(next);
+    this._param?.requestUpdate();
+  }
+
+  setData(next: { candles: Candle[]; bucketSeconds: number; samples: Map<number, BuildSample[]> }) {
+    this._candles = Array.isArray(next.candles) ? next.candles : [];
+    this._bucketSeconds = Number.isFinite(next.bucketSeconds) ? next.bucketSeconds : 0;
+    this._samples = next.samples;
+    this._param?.requestUpdate();
+  }
 }
 
 export default function TradingChart({
@@ -120,6 +495,7 @@ export default function TradingChart({
   showBuild,
   bucketSeconds,
   seriesKey,
+  priceLines,
   fib,
   fibOpacity = 1,
   fibSelected = false,
@@ -136,18 +512,23 @@ export default function TradingChart({
   const fibOpacityRef = useRef<number>(fibOpacity);
   const priceAutoScaleRef = useRef<boolean>(priceAutoScale);
   const prevPriceAutoScaleRef = useRef<boolean>(priceAutoScale);
+  const showBuildRef = useRef<boolean>(showBuild);
   const onReadyRef = useRef<Props['onReady']>(onReady);
   const onChartClickRef = useRef<Props['onChartClick']>(onChartClick);
   const onChartCrosshairMoveRef = useRef<Props['onChartCrosshairMove']>(onChartCrosshairMove);
   const onPointerEventRef = useRef<Props['onPointerEvent']>(onPointerEvent);
   const capturedOverlayPointerRef = useRef<number | null>(null);
+  const buildSlicesPrimitiveRef = useRef<BuildSlicesPrimitive | null>(null);
   const buildSamplesRef = useRef<Map<number, BuildSample[]>>(new Map());
   const buildKeyRef = useRef<string | null>(null);
   const lastBuildCandleStartRef = useRef<number | null>(null);
+  const hoverCandleTimeRef = useRef<number | null>(null);
+  const [hoverCandleTime, setHoverCandleTime] = useState<number | null>(null);
+  const priceLinesRef = useRef<Map<string, any>>(new Map());
   const seriesRef = useRef<{
     candles?: ISeriesApi<'Candlestick'>;
     volume?: ISeriesApi<'Histogram'>;
-    build?: ISeriesApi<'Line'>;
+    buildHover?: ISeriesApi<'Line'>;
     oracle?: ISeriesApi<'Line'>;
     sma20?: ISeriesApi<'Line'>;
     ema20?: ISeriesApi<'Line'>;
@@ -198,6 +579,14 @@ export default function TradingChart({
     priceAutoScaleRef.current = priceAutoScale;
   }, [priceAutoScale]);
 
+  useEffect(() => {
+    showBuildRef.current = showBuild;
+    if (!showBuild && (hoverCandleTimeRef.current != null || hoverCandleTime != null)) {
+      hoverCandleTimeRef.current = null;
+      setHoverCandleTime(null);
+    }
+  }, [showBuild, hoverCandleTime]);
+
   useEffect(() => {
     if (!containerRef.current) return;
     if (chartRef.current) return;
@@ -249,8 +638,13 @@ export default function TradingChart({
       scaleMargins: { top: 0.88, bottom: 0 },
     });
 
-    const buildSeries = chart.addSeries(LineSeries, {
-      color: '#60a5fa',
+    const buildSlicesPrimitive = new BuildSlicesPrimitive();
+    volumeSeries.attachPrimitive(buildSlicesPrimitive);
+    buildSlicesPrimitiveRef.current = buildSlicesPrimitive;
+    buildSlicesPrimitive.setEnabled(!showBuildRef.current);
+
+    const buildHoverSeries = chart.addSeries(LineSeries, {
+      color: BUILD_FLAT_COLOR,
       lineWidth: 2,
       priceFormat,
       priceScaleId: 'build',
@@ -258,7 +652,7 @@ export default function TradingChart({
       priceLineVisible: false,
       crosshairMarkerVisible: false,
     });
-    buildSeries.priceScale().applyOptions({
+    buildHoverSeries.priceScale().applyOptions({
       scaleMargins: { top: 0.72, bottom: 0.12 },
       visible: false,
       borderVisible: false,
@@ -285,7 +679,7 @@ export default function TradingChart({
     seriesRef.current = {
       candles: candleSeries,
       volume: volumeSeries,
-      build: buildSeries,
+      buildHover: buildHoverSeries,
       oracle: oracleSeries,
       sma20: smaSeries,
       ema20: emaSeries,
@@ -335,7 +729,23 @@ export default function TradingChart({
     chart.subscribeClick(onClick);
 
     const onCrosshairMove = (param: any) => {
-      if (!param?.point) return;
+      if (!param?.point) {
+        if (showBuildRef.current && hoverCandleTimeRef.current != null) {
+          hoverCandleTimeRef.current = null;
+          setHoverCandleTime(null);
+        }
+        return;
+      }
+
+      if (showBuildRef.current) {
+        const t = typeof param?.time === 'number' ? Number(param.time) : null;
+        const next = t != null && Number.isFinite(t) ? t : null;
+        if (hoverCandleTimeRef.current !== next) {
+          hoverCandleTimeRef.current = next;
+          setHoverCandleTime(next);
+        }
+      }
+
       const logical = param.logical ?? chart.timeScale().coordinateToLogical(param.point.x);
       if (logical == null) return;
       const price = candleSeries.coordinateToPrice(param.point.y);
@@ -580,15 +990,75 @@ export default function TradingChart({
         candleSeries.detachPrimitive(fibPrimitiveRef.current);
         fibPrimitiveRef.current = null;
       }
+      if (buildSlicesPrimitiveRef.current) {
+        volumeSeries.detachPrimitive(buildSlicesPrimitiveRef.current);
+        buildSlicesPrimitiveRef.current = null;
+      }
+      const lines = priceLinesRef.current;
+      for (const line of Array.from(lines.values())) {
+        try {
+          candleSeries.removePriceLine(line);
+        } catch {
+          // ignore
+        }
+      }
+      lines.clear();
       chart.remove();
       chartRef.current = null;
       seriesRef.current = {};
     };
   }, []);
 
+  useEffect(() => {
+    const candlesSeries = seriesRef.current.candles;
+    if (!candlesSeries) return;
+
+    const desired = (priceLines || []).filter((l) => l.price != null && Number.isFinite(l.price));
+    const desiredIds = new Set(desired.map((l) => l.id));
+
+    const map = priceLinesRef.current;
+    for (const [id, line] of Array.from(map.entries())) {
+      if (desiredIds.has(id)) continue;
+      try {
+        candlesSeries.removePriceLine(line);
+      } catch {
+        // ignore
+      }
+      map.delete(id);
+    }
+
+    for (const spec of desired) {
+      const opts: any = {
+        price: spec.price,
+        color: spec.color,
+        title: spec.title,
+        lineWidth: spec.lineWidth ?? 1,
+        lineStyle: spec.lineStyle ?? LineStyle.Dotted,
+        axisLabelVisible: spec.axisLabelVisible ?? true,
+      };
+
+      const existing = map.get(spec.id);
+      if (!existing) {
+        try {
+          const created = candlesSeries.createPriceLine(opts);
+          map.set(spec.id, created);
+        } catch {
+          // ignore
+        }
+        continue;
+      }
+
+      try {
+        existing.applyOptions(opts);
+      } catch {
+        // ignore
+      }
+    }
+  }, [priceLines]);
+
   useEffect(() => {
     const s = seriesRef.current;
-    if (!s.candles || !s.volume || !s.build) return;
+    if (!s.candles || !s.volume || !s.buildHover) return;
     s.candles.setData(candleData);
     s.volume.setData(volumeData);
     s.oracle?.setData(oracleData);
@@ -598,34 +1068,18 @@ export default function TradingChart({
     s.bbLower?.setData(bbLower);
     s.bbMid?.setData(bbMid);
 
-    s.build.applyOptions({ visible: showBuild });
-    if (!showBuild) {
-      buildSamplesRef.current.clear();
-      buildKeyRef.current = seriesKey;
-      lastBuildCandleStartRef.current = null;
-      s.build.setData([]);
-    }
-
-    if (buildKeyRef.current !== seriesKey) {
-      buildSamplesRef.current.clear();
-      buildKeyRef.current = seriesKey;
-      lastBuildCandleStartRef.current = null;
-    }
-
-    if (!showBuild) {
-      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 });
-      return;
-    }
-
     const bs = resolveBucketSeconds(bucketSeconds, candles);
     const eps = 1e-3;
     const maxPointsPerCandle = 600;
     const minStep = Math.max(0.5, bs / maxPointsPerCandle);
     const map = buildSamplesRef.current;
+
+    if (buildKeyRef.current !== seriesKey) {
+      map.clear();
+      buildKeyRef.current = seriesKey;
+      lastBuildCandleStartRef.current = null;
+    }
+
     const visibleStarts = new Set(candles.map((c) => c.time));
     for (const start of Array.from(map.keys())) {
       if (!visibleStarts.has(start)) map.delete(start);
@@ -671,62 +1125,26 @@ export default function TradingChart({
       lastBuildCandleStartRef.current = start;
     }
 
-    const buildRaw: LinePoint[] = [];
-    for (const c of candles) {
-      const list = map.get(c.time);
-      if (!list?.length) continue;
+    const buildPrimitive = buildSlicesPrimitiveRef.current;
+    buildPrimitive?.setData({ candles, bucketSeconds: bs, samples: map });
+    buildPrimitive?.setEnabled(!showBuild);
 
-      const startT = c.time + eps;
-      const endT = c.time + bs - eps;
-      if (!(endT > startT)) continue;
+    if (showBuild) {
+      const hoverTime = hoverCandleTime;
+      const hoverCandle = hoverTime == null ? null : candles.find((c) => c.time === hoverTime);
+      const hoverData = hoverCandle ? buildDeltaSeriesForCandle(hoverCandle, bs, map.get(hoverCandle.time)) : [];
 
-      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;
+      if (hoverData.length) {
+        s.buildHover.applyOptions({ visible: true });
+        s.buildHover.setData(hoverData);
+      } else {
+        s.buildHover.applyOptions({ visible: false });
+        s.buildHover.setData([]);
       }
-
-      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;
+    } else {
+      s.buildHover.applyOptions({ visible: false });
+      s.buildHover.setData([]);
     }
-      }
-    }
-
-    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 });
@@ -747,13 +1165,14 @@ export default function TradingChart({
     candles,
     bucketSeconds,
     seriesKey,
+    hoverCandleTime,
   ]);
 
   useEffect(() => {
     const s = seriesRef.current;
     if (!s.candles) return;
     s.candles.applyOptions({ priceFormat });
-    s.build?.applyOptions({ priceFormat });
+    s.buildHover?.applyOptions({ priceFormat });
     s.oracle?.applyOptions({ priceFormat });
     s.sma20?.applyOptions({ priceFormat });
     s.ema20?.applyOptions({ priceFormat });