feat(visualizer): add DLOB slippage chart component

apps/visualizer/src/features/market/DlobSlippageChart.tsx

@@ -0,0 +1,111 @@
+import { useEffect, useMemo, useRef } from 'react';
+import Chart from 'chart.js/auto';
+import type { DlobSlippageRow } from './useDlobSlippage';
+
+type Point = { x: number; y: number | null };
+
+function clamp01(v: number): number {
+  if (!Number.isFinite(v)) return 0;
+  return Math.max(0, Math.min(1, v));
+}
+
+export default function DlobSlippageChart({ rows }: { rows: DlobSlippageRow[] }) {
+  const canvasRef = useRef<HTMLCanvasElement | null>(null);
+  const chartRef = useRef<Chart | null>(null);
+
+  const { buy, sell, maxImpact } = useMemo(() => {
+    const buy: Point[] = [];
+    const sell: Point[] = [];
+    let maxImpact = 0;
+
+    for (const r of rows) {
+      if (!Number.isFinite(r.sizeUsd) || r.sizeUsd <= 0) continue;
+      const y = r.impactBps == null || !Number.isFinite(r.impactBps) ? null : r.impactBps;
+      if (y != null) maxImpact = Math.max(maxImpact, y);
+      if (r.side === 'buy') buy.push({ x: r.sizeUsd, y });
+      if (r.side === 'sell') sell.push({ x: r.sizeUsd, y });
+    }
+
+    buy.sort((a, b) => a.x - b.x);
+    sell.sort((a, b) => a.x - b.x);
+
+    return { buy, sell, maxImpact };
+  }, [rows]);
+
+  useEffect(() => {
+    if (!canvasRef.current) return;
+    if (chartRef.current) return;
+
+    chartRef.current = new Chart(canvasRef.current, {
+      type: 'line',
+      data: {
+        datasets: [
+          {
+            label: 'Buy',
+            data: [],
+            borderColor: 'rgba(34,197,94,0.9)',
+            backgroundColor: 'rgba(34,197,94,0.15)',
+            pointRadius: 2,
+            pointHoverRadius: 4,
+            borderWidth: 2,
+            tension: 0.2,
+            fill: false,
+          },
+          {
+            label: 'Sell',
+            data: [],
+            borderColor: 'rgba(239,68,68,0.9)',
+            backgroundColor: 'rgba(239,68,68,0.15)',
+            pointRadius: 2,
+            pointHoverRadius: 4,
+            borderWidth: 2,
+            tension: 0.2,
+            fill: false,
+          },
+        ],
+      },
+      options: {
+        responsive: true,
+        maintainAspectRatio: false,
+        animation: false,
+        parsing: false,
+        interaction: { mode: 'nearest', intersect: false },
+        plugins: {
+          legend: { labels: { color: '#e6e9ef' } },
+          tooltip: { enabled: true },
+        },
+        scales: {
+          x: {
+            type: 'linear',
+            title: { display: true, text: 'Size (USD)', color: '#c7cbd4' },
+            ticks: { color: '#c7cbd4' },
+            grid: { color: 'rgba(255,255,255,0.06)' },
+          },
+          y: {
+            type: 'linear',
+            beginAtZero: true,
+            suggestedMax: Math.max(10, maxImpact * (1 + clamp01(0.15))),
+            title: { display: true, text: 'Impact (bps)', color: '#c7cbd4' },
+            ticks: { color: '#c7cbd4' },
+            grid: { color: 'rgba(255,255,255,0.06)' },
+          },
+        },
+      },
+    });
+
+    return () => {
+      chartRef.current?.destroy();
+      chartRef.current = null;
+    };
+  }, [maxImpact]);
+
+  useEffect(() => {
+    const chart = chartRef.current;
+    if (!chart) return;
+    chart.data.datasets[0]!.data = buy as any;
+    chart.data.datasets[1]!.data = sell as any;
+    chart.update('none');
+  }, [buy, sell]);
+
+  return <canvas className="dlobSlippageChart" ref={canvasRef} />;
+}