fix: refine token usage reporting (#807)

src/components/chat/view/subcomponents/TokenUsageSummary.tsx

@@ -0,0 +1,53 @@
+import { ActivityIcon } from 'lucide-react';
+
+type TokenUsageSummaryProps = {
+  usage: Record<string, unknown> | null;
+};
+
+const formatTokenCount = (value: number) => {
+  if (!Number.isFinite(value) || value <= 0) {
+    return '0';
+  }
+
+  if (value >= 1_000_000) {
+    return `${(value / 1_000_000).toFixed(value >= 10_000_000 ? 0 : 1)}M`;
+  }
+
+  if (value >= 10_000) {
+    return `${Math.round(value / 1_000)}K`;
+  }
+
+  if (value >= 1_000) {
+    return `${(value / 1_000).toFixed(1)}K`;
+  }
+
+  return value.toLocaleString();
+};
+
+const readUsageNumber = (value: unknown) => {
+  const parsed = Number(value);
+  return Number.isFinite(parsed) ? parsed : 0;
+};
+
+export default function TokenUsageSummary({ usage }: TokenUsageSummaryProps) {
+  const breakdown =
+    usage?.breakdown && typeof usage.breakdown === 'object'
+      ? usage.breakdown as Record<string, unknown>
+      : null;
+  const inputTokens = readUsageNumber(usage?.inputTokens ?? breakdown?.input);
+  const outputTokens = readUsageNumber(usage?.outputTokens ?? breakdown?.output);
+  const usedTokens = readUsageNumber(usage?.used) || inputTokens + outputTokens;
+
+  return (
+    <div
+      className="inline-flex h-9 items-center gap-1.5 rounded-lg border border-border/70 bg-background/70 px-2 text-xs text-muted-foreground shadow-sm transition-colors hover:border-primary/25 hover:text-foreground sm:gap-2 sm:px-2.5"
+      title={`${usedTokens.toLocaleString()} tokens used`}
+    >
+      <span className="grid h-5 w-5 place-items-center rounded-md bg-primary/10 text-primary">
+        <ActivityIcon className="h-3.5 w-3.5" />
+      </span>
+      <span className="font-medium text-foreground">{formatTokenCount(usedTokens)}</span>
+      <span className="hidden text-muted-foreground/70 sm:inline">tokens</span>
+    </div>
+  );
+}