feat: add VolumeCard to overview left column (today vs 30d avg)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

1 files changed, 51 insertions, 0 deletions

diff --git a/frontend/components/prism/VolumeCard.tsx b/frontend/components/prism/VolumeCard.tsx
new file mode 100644
index 0000000..08b4059
--- /dev/null
+++ b/frontend/components/prism/VolumeCard.tsx
@@ -0,0 +1,51 @@
+import type { TickerOverview } from "@/types/api";
+import { fmtNumber } from "@/lib/format";
+
+function activityLabel(ratio: number): string {
+  if (ratio >= 1.5) return "elevated activity";
+  if (ratio < 0.7) return "below average";
+  return "normal activity";
+}
+
+export function VolumeCard({ overview }: { overview: TickerOverview }) {
+  const today = overview.stats.volume;
+  const avg = overview.stats.average_volume;
+  if (today == null && avg == null) return null;
+
+  const max = Math.max(today ?? 0, avg ?? 0);
+  const todayPct = today != null && max > 0 ? Math.round((today / max) * 100) : 0;
+  const avgPct = avg != null && max > 0 ? Math.round((avg / max) * 100) : 0;
+  const ratio = today != null && avg != null && avg > 0 ? today / avg : null;
+
+  return (
+    <section className="psm-card">
+      <div className="psm-card-head">
+        <div>
+          <div className="psm-eyebrow">Volume</div>
+          <h2 className="psm-card-title">Volume</h2>
+        </div>
+      </div>
+      <div className="psm-vol-list">
+        <div className="psm-vol-row">
+          <span className="psm-vol-label">Today</span>
+          <div className="psm-vol-track">
+            <div className="psm-vol-fill accent" style={{ width: `${todayPct}%` }} />
+          </div>
+          <span className="psm-vol-value">{today != null ? fmtNumber(today, 0) : "—"}</span>
+        </div>
+        <div className="psm-vol-row">
+          <span className="psm-vol-label">30d avg</span>
+          <div className="psm-vol-track">
+            <div className="psm-vol-fill" style={{ width: `${avgPct}%` }} />
+          </div>
+          <span className="psm-vol-value">{avg != null ? fmtNumber(avg, 0) : "—"}</span>
+        </div>
+      </div>
+      {ratio != null && (
+        <p className="psm-muted-copy" style={{ marginTop: "var(--sp-3)" }}>
+          {ratio >= 1 ? "↑" : "↓"} {ratio.toFixed(2)}× average · {activityLabel(ratio)}
+        </p>
+      )}
+    </section>
+  );
+}