Recompute account balance after bulk transaction delete

After deleting transactions, recalculate currentBalanceCents for each
affected account so the account card and net worth dashboard stay accurate.

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

src/app/api/transactions/bulk/route.ts

@@ -34,14 +34,32 @@ export async function POST(req: Request) {
   // Verify all transaction IDs belong to this user
   const owned = await prisma.transaction.findMany({
     where: { id: { in: ids }, account: { userId } },
-    select: { id: true },
+    select: { id: true, accountId: true },
   })
   if (owned.length !== ids.length) {
     return NextResponse.json({ error: 'One or more transactions not found' }, { status: 404 })
   }
 
   if (action === 'delete') {
+    const accountIds = [...new Set(owned.map((t) => t.accountId))]
+
     await prisma.transaction.deleteMany({ where: { id: { in: ids } } })
+
+    // Recompute currentBalanceCents for each affected account
+    for (const accountId of accountIds) {
+      const [balRow] = await prisma.$queryRaw<[{ balance: bigint }]>`
+        SELECT COALESCE(SUM(
+          CASE WHEN type = 'CREDIT' THEN "amountCents" ELSE -"amountCents" END
+        ), 0)::bigint AS balance
+        FROM "Transaction"
+        WHERE "accountId" = ${accountId}
+      `
+      await prisma.account.update({
+        where: { id: accountId },
+        data: { currentBalanceCents: Number(balRow.balance) },
+      })
+    }
+
     return NextResponse.json({ deleted: ids.length })
   }