fix: implement rounding for monetary values across fund and user transactions

src/app/api/admin/funds/[fundId]/route.ts

@@ -3,7 +3,7 @@ import { getServerSession } from 'next-auth'
 import { authOptions } from '@/lib/auth'
 import { prisma } from '@/lib/prisma'
 import { z } from 'zod'
-import { calcFundNav } from '@/lib/pricing'
+import { calcFundNav, round2 } from '@/lib/pricing'
 
 const patchSchema = z.object({
   addManagerUsername: z.string().optional(),
@@ -58,7 +58,7 @@ export async function PATCH(
   }
 
   if (typeof balance === 'number') {
-    await prisma.user.update({ where: { id: fund.userId }, data: { balance } })
+    await prisma.user.update({ where: { id: fund.userId }, data: { balance: round2(balance) } })
   }
 
   const updated = await prisma.hedgeFund.findUnique({
@@ -112,14 +112,14 @@ export async function DELETE(
   const portfolioValue = fund.user.positions.reduce((sum, p) => {
     const val = p.positionType === 'LONG'
       ? p.shares * p.hashtag.currentPrice
-      : p.avgBuyPrice * p.shares - (p.hashtag.currentPrice - p.avgBuyPrice) * p.shares
+      : (2 * p.avgBuyPrice - p.hashtag.currentPrice) * p.shares
     return sum + val
   }, 0)
   const nav = calcFundNav(fund.user.balance + portfolioValue, fund.sharesOutstanding)
 
   // Pay out each investor at current NAV before wiping records
   for (const inv of fund.investments) {
-    const payout = Math.max(0, inv.shares * nav)
+    const payout = Math.max(0, round2(inv.shares * nav))
     if (payout > 0) {
       await prisma.user.update({ where: { id: inv.userId }, data: { balance: { increment: payout } } })
     }

src/app/api/admin/users/[userId]/reset/route.ts

@@ -2,7 +2,7 @@ import { NextRequest, NextResponse } from 'next/server'
 import { getServerSession } from 'next-auth'
 import { authOptions } from '@/lib/auth'
 import { prisma } from '@/lib/prisma'
-import { calcFundNav } from '@/lib/pricing'
+import { calcFundNav, round2 } from '@/lib/pricing'
 
 const STARTING_BALANCE = 2000
 
@@ -106,7 +106,7 @@ export async function POST(
       }, 0)
       const fundTotalValue = inv.fund.user.balance + fundPortfolioValue
       const nav = calcFundNav(fundTotalValue, inv.fund.sharesOutstanding)
-      const payout = Math.max(0, inv.shares * nav)
+      const payout = Math.max(0, round2(inv.shares * nav))
       return [
         prisma.hedgeFund.update({
           where: { id: inv.fundId },

src/app/api/admin/users/[userId]/route.ts

@@ -3,7 +3,7 @@ import { getServerSession } from 'next-auth'
 import { authOptions } from '@/lib/auth'
 import { prisma } from '@/lib/prisma'
 import { z } from 'zod'
-import { calcFundNav } from '@/lib/pricing'
+import { calcFundNav, round2 } from '@/lib/pricing'
 
 const schema = z.object({
   balance: z.number().min(0).optional(),
@@ -92,13 +92,13 @@ export async function DELETE(
     const portfolioValue = fund.user.positions.reduce((sum, p) => {
       const val = p.positionType === 'LONG'
         ? p.shares * p.hashtag.currentPrice
-        : p.avgBuyPrice * p.shares - (p.hashtag.currentPrice - p.avgBuyPrice) * p.shares
+        : (2 * p.avgBuyPrice - p.hashtag.currentPrice) * p.shares
       return sum + val
     }, 0)
     const nav = calcFundNav(fund.user.balance + portfolioValue, fund.sharesOutstanding)
-    const payout = inv.shares * nav
+    const payout = round2(Math.max(0, inv.shares * nav))
     await prisma.$transaction([
-      prisma.user.update({ where: { id: fund.userId }, data: { balance: { decrement: payout } } }),
+      prisma.user.update({ where: { id: fund.userId }, data: { balance: { decrement: round2(Math.max(0, payout)) } } }),
       prisma.hedgeFund.update({ where: { id: fund.id }, data: { sharesOutstanding: { decrement: inv.shares } } }),
     ])
   }

src/app/api/funds/[slug]/invest/route.ts

@@ -2,7 +2,7 @@ import { NextRequest, NextResponse } from 'next/server'
 import { getServerSession } from 'next-auth'
 import { authOptions } from '@/lib/auth'
 import { prisma } from '@/lib/prisma'
-import { calcFundNav } from '@/lib/pricing'
+import { calcFundNav, round2 } from '@/lib/pricing'
 
 export async function POST(req: NextRequest, { params }: { params: { slug: string } }) {
   const session = await getServerSession(authOptions)
@@ -10,7 +10,7 @@ export async function POST(req: NextRequest, { params }: { params: { slug: strin
 
   const slug = decodeURIComponent(params.slug).toLowerCase()
   const body = await req.json()
-  const amount = Number(body.amount)
+  const amount = round2(Number(body.amount))
 
   if (!amount || amount < 1) {
     return NextResponse.json({ error: 'Minimum investment is $1' }, { status: 400 })

src/app/api/funds/[slug]/redeem/route.ts

@@ -2,7 +2,7 @@ import { NextRequest, NextResponse } from 'next/server'
 import { getServerSession } from 'next-auth'
 import { authOptions } from '@/lib/auth'
 import { prisma } from '@/lib/prisma'
-import { calcFundNav } from '@/lib/pricing'
+import { calcFundNav, round2 } from '@/lib/pricing'
 
 export async function POST(req: NextRequest, { params }: { params: { slug: string } }) {
   const session = await getServerSession(authOptions)
@@ -50,7 +50,7 @@ export async function POST(req: NextRequest, { params }: { params: { slug: strin
   }, 0)
   const totalValue = fund.user.balance + portfolioValue
   const nav = calcFundNav(totalValue, fund.sharesOutstanding)
-  const payout = sharesToRedeem * nav
+  const payout = round2(sharesToRedeem * nav)
 
   if (fund.user.balance < payout) {
     return NextResponse.json({ error: 'Fund has insufficient cash to redeem. Try a smaller amount.' }, { status: 400 })

src/app/api/lottery/pick/route.ts

@@ -2,6 +2,7 @@ import { NextRequest, NextResponse } from 'next/server'
 import { getServerSession } from 'next-auth'
 import { authOptions } from '@/lib/auth'
 import { prisma } from '@/lib/prisma'
+import { round2 } from '@/lib/pricing'
 import { GRID_SIZE, PRIZE_MAP } from '@/lib/lottery'
 
 function buildPrizes(): number[] {
@@ -68,7 +69,7 @@ export async function POST(req: NextRequest) {
     prisma.user.update({
       where: { id: user.id },
       data: {
-        balance: { increment: winAmount },
+        balance: { increment: round2(winAmount) },
         lastLotteryAt: now,
       },
     }),

src/app/api/trade/route.ts

@@ -2,7 +2,7 @@ import { NextRequest, NextResponse } from 'next/server'
 import { getServerSession } from 'next-auth'
 import { authOptions } from '@/lib/auth'
 import { prisma } from '@/lib/prisma'
-import { calcTrade } from '@/lib/pricing'
+import { calcTrade, round2 } from '@/lib/pricing'
 import { formatCurrency } from '@/lib/utils'
 import { z } from 'zod'
 
@@ -105,7 +105,7 @@ export async function POST(req: NextRequest) {
     // Update user balance
     await tx.user.update({
       where: { id: user.id },
-      data: { balance: { increment: balanceDelta } },
+      data: { balance: { increment: round2(balanceDelta) } },
     })
 
     // Update / create position

src/app/api/user/me/reset/route.ts

@@ -2,7 +2,7 @@ import { NextRequest, NextResponse } from 'next/server'
 import { getServerSession } from 'next-auth'
 import { authOptions } from '@/lib/auth'
 import { prisma } from '@/lib/prisma'
-import { calcFundNav } from '@/lib/pricing'
+import { calcFundNav, round2 } from '@/lib/pricing'
 
 const STARTING_BALANCE = 2000
 
@@ -108,7 +108,7 @@ export async function POST(req: NextRequest) {
       }, 0)
       const fundTotalValue = inv.fund.user.balance + fundPortfolioValue
       const nav = calcFundNav(fundTotalValue, inv.fund.sharesOutstanding)
-      const payout = Math.max(0, inv.shares * nav)
+      const payout = Math.max(0, round2(inv.shares * nav))
       return [
         prisma.hedgeFund.update({
           where: { id: inv.fundId },

src/app/api/user/me/route.ts

@@ -2,7 +2,7 @@ import { NextRequest, NextResponse } from 'next/server'
 import { getServerSession } from 'next-auth'
 import { authOptions } from '@/lib/auth'
 import { prisma } from '@/lib/prisma'
-import { calcFundNav } from '@/lib/pricing'
+import { calcFundNav, round2 } from '@/lib/pricing'
 
 const USERNAME_RE = /^[a-z0-9_]{3,20}$/ // validated after toLowerCase
 
@@ -135,11 +135,11 @@ export async function DELETE() {
     const portfolioValue = fund.user.positions.reduce((sum, p) => {
       const val = p.positionType === 'LONG'
         ? p.shares * p.hashtag.currentPrice
-        : p.avgBuyPrice * p.shares - (p.hashtag.currentPrice - p.avgBuyPrice) * p.shares
+        : (2 * p.avgBuyPrice - p.hashtag.currentPrice) * p.shares
       return sum + val
     }, 0)
     const nav = calcFundNav(fund.user.balance + portfolioValue, fund.sharesOutstanding)
-    const payout = inv.shares * nav
+    const payout = round2(Math.max(0, inv.shares * nav))
     await prisma.$transaction([
       prisma.user.update({ where: { id: fund.userId }, data: { balance: { decrement: payout } } }),
       prisma.hedgeFund.update({ where: { id: fund.id }, data: { sharesOutstanding: { decrement: inv.shares } } }),

src/lib/pricing.ts

@@ -39,6 +39,9 @@ export function getBalanceTier(balance: number): BalanceTier {
   return                           { level: 1, pointsPerDay: 1, nextThreshold: 10_000 }
 }
 
+/** Round a dollar amount to 2 decimal places for DB storage. */
+export const round2 = (n: number) => Math.round(n * 100) / 100
+
 /** Calculate NAV (net asset value) per fund share. Returns 1.00 if no shares outstanding. */
 export function calcFundNav(totalValue: number, sharesOutstanding: number): number {
   if (sharesOutstanding <= 0) return 1.00

src/worker/index.ts

@@ -74,7 +74,7 @@ async function forceClosePositions(hashtagId: string, price: number, tag: string
     await prisma.$transaction([
       prisma.user.update({
         where: { id: pos.userId },
-        data: { balance: { increment: balanceDelta } },
+        data: { balance: { increment: round2(balanceDelta) } },
       }),
       prisma.position.update({
         where: { id: pos.id },