feat(dashboard): 构建基于 Big.js 的持仓聚合引擎与总览卡片

app/dashboard/page.tsx

@@ -1,14 +1,53 @@
 import { Card, CardContent, CardHeader, CardTitle } from '@/components/ui/card';
+import { getPortfolioPositions } from '@/actions/portfolio';
+import { formatQuantity } from '@/lib/formatters';
+
+export default async function DashboardPage() {
+  const positions = await getPortfolioPositions();
 
-export default function DashboardPage() {
   return (
-    <Card className="max-w-md">
-      <CardHeader>
-        <CardTitle>欢迎来到 Omniledger</CardTitle>
-      </CardHeader>
-      <CardContent>
+    <div className="space-y-6">
+      <div>
+        <h1 className="text-3xl font-bold">欢迎来到 Omniledger</h1>
         <p className="text-muted-foreground">您的跨界记账中枢。</p>
-      </CardContent>
-    </Card>
+      </div>
+
+      <div className="grid grid-cols-1 md:grid-cols-3 gap-4">
+        {positions.length === 0 ? (
+          <Card>
+            <CardContent className="pt-6">
+              <p className="text-muted-foreground">暂无持仓，请先添加资产和交易记录。</p>
+            </CardContent>
+          </Card>
+        ) : (
+          positions.map((pos) => (
+            <Card key={pos.assetId}>
+              <CardHeader>
+                <CardTitle className="flex items-center justify-between">
+                  <span>{pos.symbol}</span>
+                  <span className="text-sm font-normal text-muted-foreground">
+                    {pos.type}
+                  </span>
+                </CardTitle>
+              </CardHeader>
+              <CardContent>
+                <div className="space-y-2">
+                  <div className="flex justify-between">
+                    <span className="text-muted-foreground">持仓数量</span>
+                    <span className="font-medium">
+                      {formatQuantity(pos.quantity, pos.type)}
+                    </span>
+                  </div>
+                  <div className="flex justify-between">
+                    <span className="text-muted-foreground">结算币种</span>
+                    <span className="font-medium">{pos.baseCurrency}</span>
+                  </div>
+                </div>
+              </CardContent>
+            </Card>
+          ))
+        )}
+      </div>
+    </div>
   );
-}
+}

src/actions/portfolio.ts

@@ -0,0 +1,68 @@
+'use server';
+
+import { db } from '@/db';
+import { transactions, assets } from '@/db/schema';
+import Big from 'big.js';
+import { desc } from 'drizzle-orm';
+
+export async function getPortfolioPositions() {
+  const allTransactions = await db
+    .select({
+      txType: transactions.txType,
+      quantity: transactions.quantity,
+      assetId: transactions.assetId,
+      assetSymbol: assets.symbol,
+      assetType: assets.type,
+      assetBaseCurrency: assets.baseCurrency,
+    })
+    .from(transactions)
+    .leftJoin(assets, assets.id.eq(transactions.assetId))
+    .orderBy(desc(transactions.executedAt));
+
+  const holdings = new Map<string, {
+    assetId: string;
+    symbol: string;
+    type: string;
+    quantity: Big;
+    baseCurrency: string;
+  }>();
+
+  for (const tx of allTransactions) {
+    if (!tx.assetId) continue;
+
+    const existing = holdings.get(tx.assetId);
+    if (!existing) {
+      holdings.set(tx.assetId, {
+        assetId: tx.assetId,
+        symbol: tx.assetSymbol || tx.assetId,
+        type: tx.assetType || 'CASH',
+        quantity: new Big('0'),
+        baseCurrency: tx.assetBaseCurrency || '',
+      });
+    }
+
+    const holding = holdings.get(tx.assetId)!;
+
+    if (tx.txType === 'BUY' || tx.txType === 'AIRDROP') {
+      holding.quantity = holding.quantity.plus(tx.quantity);
+    } else if (tx.txType === 'SELL') {
+      holding.quantity = holding.quantity.minus(tx.quantity);
+    } else if (tx.txType === 'DIVIDEND') {
+      holding.quantity = holding.quantity.plus(tx.quantity);
+    }
+  }
+
+  const result = [];
+  for (const [_, holding] of holdings) {
+    if (holding.quantity.lte(0)) continue;
+    result.push({
+      assetId: holding.assetId,
+      symbol: holding.symbol,
+      type: holding.type,
+      quantity: holding.quantity.toString(),
+      baseCurrency: holding.baseCurrency,
+    });
+  }
+
+  return result;
+}