fix: default daily card to next available recommendations

platform/web/app/api/analytics/daily-card/route.ts

@@ -17,9 +17,47 @@ function getTaipeiDate(): string {
   return `${year}-${month}-${day}`;
 }
 
+async function resolveDefaultDate(today: string): Promise<string> {
+  try {
+    const calendarResponse = await fetch(
+      `${ANALYTICS_BACKEND}/analytics/daily-card-calendar?start_date=${encodeURIComponent(today)}&days=14`,
+      {
+        method: 'GET',
+        cache: 'no-store',
+        headers: {
+          'Content-Type': 'application/json',
+        },
+      },
+    );
+
+    if (!calendarResponse.ok) {
+      return today;
+    }
+
+    const calendar = (await calendarResponse.json()) as {
+      dates?: Array<{
+        date?: string;
+        recommendation_count?: number;
+        market_data_status?: string;
+      }>;
+    };
+    const resolved = calendar.dates?.find((entry) => {
+      const recommendationCount = Number(entry.recommendation_count || 0);
+      return Boolean(entry.date)
+        && recommendationCount > 0
+        && entry.market_data_status !== 'snapshot_missing_after_kickoff';
+    });
+
+    return resolved?.date || today;
+  } catch {
+    return today;
+  }
+}
+
 export async function GET(request: Request) {
   const { searchParams } = new URL(request.url);
-  const targetDate = searchParams.get('date') || getTaipeiDate();
+  const requestedDate = searchParams.get('date');
+  const targetDate = requestedDate || await resolveDefaultDate(getTaipeiDate());
 
   if (!/^\d{4}-\d{2}-\d{2}$/.test(targetDate)) {
     return NextResponse.json({ message: '日期格式必須為 YYYY-MM-DD' }, { status: 400 });
@@ -42,6 +80,7 @@ export async function GET(request: Request) {
     const data = (await response.json()) as Record<string, unknown>;
     return NextResponse.json({
       generated_at: new Date().toISOString(),
+      requested_date: requestedDate || null,
       target_date: targetDate,
       ...data,
     });