chore: add backend seed script and root seed command

Author: Arun-kushwaha007

apps/backend/package.json

@@ -9,7 +9,8 @@
                     "lint":  "tsc --noEmit",
                     "test":  "jest --runInBand --passWithNoTests",
                     "prisma:generate":  "prisma generate",
-                    "prisma:migrate":  "prisma migrate dev"
+                    "prisma:migrate":  "prisma migrate dev",
+                    "seed":  "ts-node prisma/seed.ts"
                 },
     "dependencies":  {
                          "@fairshare/shared-types":  "workspace:*",

apps/backend/prisma/seed.ts

@@ -0,0 +1,112 @@
+import { PrismaClient } from '@prisma/client';
+import { hash } from 'bcrypt';
+
+const prisma = new PrismaClient();
+
+async function main(): Promise<void> {
+  await prisma.$transaction([
+    prisma.activity.deleteMany(),
+    prisma.receipt.deleteMany(),
+    prisma.settlement.deleteMany(),
+    prisma.balance.deleteMany(),
+    prisma.split.deleteMany(),
+    prisma.expense.deleteMany(),
+    prisma.groupMember.deleteMany(),
+    prisma.group.deleteMany(),
+    prisma.refreshToken.deleteMany(),
+    prisma.pushToken.deleteMany(),
+    prisma.user.deleteMany(),
+  ]);
+
+  const passwordHash = await hash('Password@123', 10);
+
+  const [u1, u2, u3] = await prisma.$transaction([
+    prisma.user.create({
+      data: { email: 'alice@fairshare.dev', name: 'Alice', passwordHash },
+    }),
+    prisma.user.create({
+      data: { email: 'bob@fairshare.dev', name: 'Bob', passwordHash },
+    }),
+    prisma.user.create({
+      data: { email: 'cara@fairshare.dev', name: 'Cara', passwordHash },
+    }),
+  ]);
+
+  const [g1, g2] = await prisma.$transaction([
+    prisma.group.create({ data: { name: 'Trip Squad', currency: 'USD', createdBy: u1.id } }),
+    prisma.group.create({ data: { name: 'Flatmates', currency: 'USD', createdBy: u2.id } }),
+  ]);
+
+  await prisma.groupMember.createMany({
+    data: [
+      { groupId: g1.id, userId: u1.id, role: 'OWNER' },
+      { groupId: g1.id, userId: u2.id, role: 'MEMBER' },
+      { groupId: g1.id, userId: u3.id, role: 'MEMBER' },
+      { groupId: g2.id, userId: u2.id, role: 'OWNER' },
+      { groupId: g2.id, userId: u1.id, role: 'MEMBER' },
+      { groupId: g2.id, userId: u3.id, role: 'MEMBER' },
+    ],
+  });
+
+  const groups = [g1, g2];
+  const users = [u1, u2, u3];
+
+  for (let i = 0; i < 10; i += 1) {
+    const group = groups[i % 2];
+    const payer = users[i % 3];
+    const total = BigInt((i + 1) * 1000);
+    const perHead = total / 3n;
+
+    const expense = await prisma.expense.create({
+      data: {
+        groupId: group.id,
+        payerId: payer.id,
+        description: `Seed expense ${i + 1}`,
+        totalAmountCents: total,
+        currency: 'USD',
+      },
+    });
+
+    await prisma.split.createMany({
+      data: users.map((user) => ({
+        expenseId: expense.id,
+        userId: user.id,
+        owedAmountCents: perHead,
+        paidAmountCents: user.id === payer.id ? total : 0n,
+      })),
+    });
+
+    await prisma.activity.create({
+      data: {
+        groupId: group.id,
+        actorUserId: payer.id,
+        type: 'expense_created',
+        entityId: expense.id,
+        metadata: { totalAmountCents: total.toString() },
+      },
+    });
+  }
+
+  // minimal baseline balances for demo visibility
+  await prisma.balance.createMany({
+    data: [
+      { groupId: g1.id, userId: u2.id, counterpartyUserId: u1.id, amountCents: -500n },
+      { groupId: g1.id, userId: u1.id, counterpartyUserId: u2.id, amountCents: 500n },
+      { groupId: g2.id, userId: u3.id, counterpartyUserId: u2.id, amountCents: -700n },
+      { groupId: g2.id, userId: u2.id, counterpartyUserId: u3.id, amountCents: 700n },
+    ],
+  });
+
+  // eslint-disable-next-line no-console
+  console.log('Seed complete: 3 users, 2 groups, 10 expenses');
+}
+
+main()
+  .catch(async (error) => {
+    // eslint-disable-next-line no-console
+    console.error(error);
+    process.exitCode = 1;
+  })
+  .finally(async () => {
+    await prisma.$disconnect();
+  });

package.json

@@ -1,16 +1,17 @@
 {
-  "name": "fairshare",
-  "private": true,
-  "packageManager": "pnpm@10.6.1",
-  "scripts": {
-    "build": "turbo run build",
-    "dev": "turbo run dev --parallel",
-    "lint": "turbo run lint",
-    "test": "turbo run test",
-    "format": "turbo run format"
-  },
-  "devDependencies": {
-    "turbo": "^2.5.0",
-    "typescript": "^5.7.3"
-  }
+    "name":  "fairshare",
+    "private":  true,
+    "packageManager":  "pnpm@10.6.1",
+    "scripts":  {
+                    "build":  "turbo run build",
+                    "dev":  "turbo run dev --parallel",
+                    "lint":  "turbo run lint",
+                    "test":  "turbo run test",
+                    "format":  "turbo run format",
+                    "seed":  "pnpm --filter backend seed"
+                },
+    "devDependencies":  {
+                            "turbo":  "^2.5.0",
+                            "typescript":  "^5.7.3"
+                        }
 }