diff --git a/src/lib/__tests__/integration/e2e-workflows.test.ts b/src/lib/__tests__/integration/e2e-workflows.test.ts
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+/**
+ * End-to-End Workflow Integration Tests
+ *
+ * Tests the three critical ISP business processes end-to-end, exercising
+ * multiple services in sequence to prove they integrate correctly and
+ * produce accurate accounting entries.
+ *
+ * INFRA-04: Prove the system works as a coherent whole, not just isolated units.
+ *
+ * Workflow 1: Subscriber Registration -> Invoice Generation -> Payment Recording
+ * Workflow 2: Collector Collection -> Remittance Verification
+ * Workflow 3: Ticket Creation -> Job Order -> Completion -> Auto-Resolve
+ *
+ * CLEANUP ORDER (comprehensive, covering all subsystems):
+ * ticketComments -> jobOrders -> tickets -> ticketCategories ->
+ * collectionAllocations -> collections -> remittances ->
+ * paymentAllocations -> payments -> invoiceLines -> invoices ->
+ * journalEntryLines -> null reversesEntryId -> journalEntries ->
+ * stockMovements -> inventoryItems -> expenses -> vendors ->
+ * expenseCategories (custom) -> subscribers -> servicePlans ->
+ * tenantSettings -> accountingPeriods -> accounts ->
+ * zoneAssignments -> zones -> technicianProfiles -> jobTypeRates ->
+ * expenseCategories (system) -> users -> tenant
+ */
+
+import { prisma } from "@/lib/prisma";
+import { withTenantContext } from "@/lib/prisma-tenant";
+import { seedChartOfAccounts } from "@/lib/accounting/seed-coa";
+import { JournalEntryService } from "@/lib/accounting/journal-entry-service";
+import { createSubscriber } from "@/lib/services/subscriber-service";
+import {
+  generateInvoiceForSubscriber,
+  computeBillingPeriod,
+} from "@/lib/services/billing-service";
+import { recordPayment } from "@/lib/services/payment-service";
+import { recordCollection } from "@/lib/services/collector-service";
+import {
+  createRemittance,
+  verifyRemittance,
+} from "@/lib/services/remittance-service";
+import { createTicket, transitionTicketStatus } from "@/lib/services/ticket-service";
+import {
+  createJobOrder,
+  updateJobOrderStatus,
+} from "@/lib/services/job-order-service";
+import { DashboardService } from "@/lib/services/dashboard-service";
+import {
+  Prisma,
+  Role,
+  TenantStatus,
+  BillingType,
+  PaymentMethod,
+  TicketPriority,
+  TicketSource,
+  TicketStatus,
+  JobOrderStatus,
+} from "@prisma/client";
+
+// ---------------------------------------------------------------------------
+// Shared test state
+// ---------------------------------------------------------------------------
+
+const TS = Date.now();
+
+let tenantId: string;
+let adminUserId: string;
+let officeStaffUserId: string;
+let collectorUserId: string;
+let technicianUserId: string;
+let servicePlanId: string;
+let zoneId: string;
+let ticketCategoryId: string;
+
+// Billing workflow state
+let subscriberId: string;
+let subscriberAccountNumber: string;
+let invoice1Id: string;
+let invoice2Id: string;
+
+// Collection workflow state
+let collectionSubscriberId: string;
+let collectionInvoiceId: string;
+
+// ---------------------------------------------------------------------------
+// Helpers
+// ---------------------------------------------------------------------------
+
+function tp() {
+  return withTenantContext(tenantId);
+}
+
+let invoiceCounter = 0;
+
+/**
+ * Helper to create a raw invoice for tests that need one without going
+ * through the full billing service (e.g., collection workflow).
+ */
+async function createRawInvoice(
+  subscriberIdArg: string,
+  amount: number,
+  status = "SENT" as const,
+) {
+  invoiceCounter++;
+  const periodStart = new Date(Date.UTC(2025, 0, invoiceCounter));
+  return prisma.invoice.create({
+    data: {
+      tenantId,
+      invoiceNumber: `INV-E2E-${TS}-${invoiceCounter}`,
+      subscriberId: subscriberIdArg,
+      periodStart,
+      periodEnd: new Date(Date.UTC(2025, 0, invoiceCounter + 30)),
+      dueDate: new Date(Date.UTC(2025, 1, invoiceCounter)),
+      subtotal: new Prisma.Decimal(amount),
+      totalAmount: new Prisma.Decimal(amount),
+      amountPaid: new Prisma.Decimal(0),
+      status,
+    } as Record<string, unknown>,
+  });
+}
+
+// ---------------------------------------------------------------------------
+// Setup / Teardown
+// ---------------------------------------------------------------------------
+
+beforeAll(async () => {
+  // 1. Create tenant
+  const tenant = await prisma.tenant.create({
+    data: {
+      name: `E2E Workflow Test ${TS}`,
+      slug: `e2e-workflow-${TS}`,
+      ownerEmail: `e2e-${TS}@test.example`,
+      status: TenantStatus.ACTIVE,
+    },
+  });
+  tenantId = tenant.id;
+
+  // 2. Seed COA
+  await prisma.$transaction(async (tx) => {
+    // eslint-disable-next-line @typescript-eslint/no-explicit-any
+    await seedChartOfAccounts(tx as any, tenantId);
+  });
+
+  // 3. Seed ticket categories
+  const cat = await prisma.ticketCategory.create({
+    data: { name: "No Connection", tenantId, isActive: true },
+  });
+  ticketCategoryId = cat.id;
+
+  // 4. Create users
+  const admin = await prisma.user.create({
+    data: {
+      email: `e2e-admin-${TS}@test.example`,
+      passwordHash: "hashed",
+      firstName: "E2E",
+      lastName: "Admin",
+      tenantId,
+      roles: [Role.ADMIN],
+      isActive: true,
+    },
+  });
+  adminUserId = admin.id;
+
+  const officeStaff = await prisma.user.create({
+    data: {
+      email: `e2e-office-${TS}@test.example`,
+      passwordHash: "hashed",
+      firstName: "E2E",
+      lastName: "OfficeStaff",
+      tenantId,
+      roles: [Role.OFFICE_STAFF],
+      isActive: true,
+    },
+  });
+  officeStaffUserId = officeStaff.id;
+
+  const collector = await prisma.user.create({
+    data: {
+      email: `e2e-collector-${TS}@test.example`,
+      passwordHash: "hashed",
+      firstName: "E2E",
+      lastName: "Collector",
+      tenantId,
+      roles: [Role.COLLECTOR],
+      isActive: true,
+    },
+  });
+  collectorUserId = collector.id;
+
+  const technician = await prisma.user.create({
+    data: {
+      email: `e2e-tech-${TS}@test.example`,
+      passwordHash: "hashed",
+      firstName: "E2E",
+      lastName: "Technician",
+      tenantId,
+      roles: [Role.TECHNICIAN],
+      isActive: true,
+    },
+  });
+  technicianUserId = technician.id;
+
+  // 5. Create service plan
+  const plan = await prisma.servicePlan.create({
+    data: {
+      tenantId,
+      name: `Fiber 50 Mbps ${TS}`,
+      speed: "50 Mbps",
+      monthlyPrice: new Prisma.Decimal(1500),
+      billingType: BillingType.POSTPAID,
+    },
+  });
+  servicePlanId = plan.id;
+
+  // 6. Create zone and assign collector
+  const zone = await prisma.zone.create({
+    data: { tenantId, name: `Zone Alpha ${TS}` },
+  });
+  zoneId = zone.id;
+
+  await prisma.zoneAssignment.create({
+    data: { tenantId, userId: collectorUserId, zoneId },
+  });
+}, 60000);
+
+afterAll(async () => {
+  // Comprehensive cleanup order covering all subsystems
+  await prisma.ticketComment.deleteMany({ where: { tenantId } });
+  await prisma.jobOrder.deleteMany({ where: { tenantId } });
+  await prisma.ticket.deleteMany({ where: { tenantId } });
+  await prisma.ticketCategory.deleteMany({ where: { tenantId } });
+  await prisma.collectionAllocation.deleteMany({ where: { tenantId } });
+  await prisma.collection.deleteMany({ where: { tenantId } });
+  await prisma.remittance.deleteMany({ where: { tenantId } });
+  await prisma.paymentAllocation.deleteMany({ where: { tenantId } });
+  await prisma.payment.deleteMany({ where: { tenantId } });
+  await prisma.invoiceLine.deleteMany({ where: { tenantId } });
+  await prisma.invoice.deleteMany({ where: { tenantId } });
+  await prisma.journalEntryLine.deleteMany({ where: { tenantId } });
+  await prisma.journalEntry.updateMany({
+    where: { tenantId, reversesEntryId: { not: null } },
+    data: { reversesEntryId: null },
+  });
+  await prisma.journalEntry.deleteMany({ where: { tenantId } });
+  await prisma.stockMovement.deleteMany({ where: { tenantId } });
+  await prisma.inventoryItem.deleteMany({ where: { tenantId } });
+  await prisma.expense.deleteMany({ where: { tenantId } });
+  await prisma.vendor.deleteMany({ where: { tenantId } });
+  await prisma.expenseCategory.deleteMany({
+    where: { tenantId, isSystemCategory: false },
+  });
+  await prisma.subscriber.deleteMany({ where: { tenantId } });
+  await prisma.servicePlan.deleteMany({ where: { tenantId } });
+  await prisma.tenantSettings.deleteMany({ where: { tenantId } });
+  await prisma.accountingPeriod.deleteMany({ where: { tenantId } });
+  await prisma.account.deleteMany({ where: { tenantId } });
+  await prisma.zoneAssignment.deleteMany({ where: { tenantId } });
+  await prisma.zone.deleteMany({ where: { tenantId } });
+  await prisma.technicianProfile.deleteMany({ where: { tenantId } });
+  await prisma.jobTypeRate.deleteMany({ where: { tenantId } });
+  await prisma.expenseCategory.deleteMany({ where: { tenantId } });
+  await prisma.user.deleteMany({ where: { tenantId } });
+  await prisma.tenant.deleteMany({ where: { id: tenantId } });
+});
+
+// =============================================================================
+// WORKFLOW 1: Subscriber Registration -> Invoice -> Payment -> Balanced Books
+// =============================================================================
+
+describe("E2E: Billing Workflow", () => {
+  test("1. Register a new subscriber", async () => {
+    const subscriber = await createSubscriber(tp(), {
+      firstName: "Juan",
+      lastName: "dela Cruz",
+      address: "123 Mango St, Barangay 1",
+      servicePlanId,
+      zoneId,
+    });
+
+    subscriberId = subscriber.id;
+    subscriberAccountNumber = subscriber.accountNumber;
+
+    // Subscriber created with ACTIVE status
+    expect(subscriber.status).toBe("ACTIVE");
+    // Account number generated with SUB-NNNN format
+    expect(subscriber.accountNumber).toMatch(/^SUB-\d{4,}$/);
+    // Correct plan assigned
+    expect(subscriber.servicePlanId).toBe(servicePlanId);
+    expect(subscriber.servicePlan.monthlyPrice.toNumber()).toBe(1500);
+  });
+
+  test("2. Generate invoice for subscriber", async () => {
+    // Load subscriber with plan for billing service
+    const subscriber = await tp().subscriber.findFirst({
+      where: { id: subscriberId },
+      include: { servicePlan: true },
+    });
+    expect(subscriber).not.toBeNull();
+
+    const period = computeBillingPeriod(new Date(), subscriber!.billingDay);
+
+    const result = await generateInvoiceForSubscriber(
+      tp(),
+      tenantId,
+      subscriber!,
+      period,
+      adminUserId,
+    );
+
+    expect(result).not.toBeNull();
+    // eslint-disable-next-line @typescript-eslint/no-explicit-any
+    const invoice = (result as any).invoice;
+    invoice1Id = invoice.id;
+
+    // Invoice created with correct amount matching plan price
+    expect(new Prisma.Decimal(invoice.totalAmount).toNumber()).toBe(1500);
+    // Invoice has SENT status (unpaid)
+    expect(invoice.status).toBe("SENT");
+
+    // Verify JE posted: DR 1100 AR, CR 4010 Service Revenue
+    const trialBalance = await JournalEntryService.getTrialBalance({
+      tenantPrisma: tp(),
+    });
+    const arLine = trialBalance.find((l) => l.accountCode === "1100");
+    const revLine = trialBalance.find((l) => l.accountCode === "4010");
+    // AR should have a debit balance of 1500
+    expect(arLine!.debitBalance.toNumber()).toBe(1500);
+    // Revenue should have a credit balance of 1500
+    expect(revLine!.creditBalance.toNumber()).toBe(1500);
+  });
+
+  test("3. Record full payment against invoice", async () => {
+    const paymentResult = await recordPayment(tp(), tenantId, {
+      subscriberId,
+      amount: 1500,
+      paymentMethod: PaymentMethod.CASH,
+      paymentDate: new Date(),
+      idempotencyKey: `e2e-full-pay-${TS}`,
+      recordedById: adminUserId,
+    });
+
+    // Payment created with COMPLETED status
+    expect(paymentResult.payment.status).toBe("COMPLETED");
+    expect(paymentResult.idempotent).toBe(false);
+    // Full amount allocated
+    expect(paymentResult.allocations.length).toBe(1);
+    expect(paymentResult.allocations[0].amount.toNumber()).toBe(1500);
+
+    // Invoice status = PAID
+    const invoice = await tp().invoice.findFirst({
+      where: { id: invoice1Id },
+    });
+    expect(invoice!.status).toBe("PAID");
+    expect(new Prisma.Decimal(invoice!.amountPaid).toNumber()).toBe(1500);
+
+    // JE posted: DR 1010 Cash, CR 1100 AR
+    const trialBalance = await JournalEntryService.getTrialBalance({
+      tenantPrisma: tp(),
+    });
+    const cashLine = trialBalance.find((l) => l.accountCode === "1010");
+    // Cash should have debit balance of 1500
+    expect(cashLine!.debitBalance.toNumber()).toBe(1500);
+    // AR should now be zero (1500 debit from invoice - 1500 credit from payment)
+    const arLine = trialBalance.find((l) => l.accountCode === "1100");
+    expect(arLine!.debitBalance.toNumber()).toBe(0);
+    expect(arLine!.creditBalance.toNumber()).toBe(0);
+  });
+
+  test("4. Record partial payment on second invoice", async () => {
+    // Generate second invoice
+    const subscriber = await tp().subscriber.findFirst({
+      where: { id: subscriberId },
+      include: { servicePlan: true },
+    });
+
+    // Use a different period to avoid idempotency skip
+    const period = {
+      periodStart: new Date(Date.UTC(2025, 5, 15)),
+      periodEnd: new Date(Date.UTC(2025, 6, 14)),
+      dueDate: new Date(Date.UTC(2025, 7, 14)),
+    };
+
+    const result2 = await generateInvoiceForSubscriber(
+      tp(),
+      tenantId,
+      subscriber!,
+      period,
+      adminUserId,
+    );
+    expect(result2).not.toBeNull();
+    // eslint-disable-next-line @typescript-eslint/no-explicit-any
+    invoice2Id = (result2 as any).invoice.id;
+
+    // Record partial payment (50%)
+    const paymentResult = await recordPayment(tp(), tenantId, {
+      subscriberId,
+      amount: 750,
+      paymentMethod: PaymentMethod.CASH,
+      paymentDate: new Date(),
+      idempotencyKey: `e2e-partial-pay-${TS}`,
+      recordedById: adminUserId,
+    });
+
+    expect(paymentResult.payment.status).toBe("COMPLETED");
+    expect(paymentResult.allocations[0].amount.toNumber()).toBe(750);
+
+    // Invoice status = PARTIAL, amountPaid = 750
+    const invoice2 = await tp().invoice.findFirst({
+      where: { id: invoice2Id },
+    });
+    expect(invoice2!.status).toBe("PARTIAL");
+    expect(new Prisma.Decimal(invoice2!.amountPaid).toNumber()).toBe(750);
+
+    // JE for partial amount is balanced
+    const trialBalance = await JournalEntryService.getTrialBalance({
+      tenantPrisma: tp(),
+    });
+    const totalDebits = trialBalance.reduce(
+      (sum, l) => sum.plus(l.debitBalance),
+      new Prisma.Decimal(0),
+    );
+    const totalCredits = trialBalance.reduce(
+      (sum, l) => sum.plus(l.creditBalance),
+      new Prisma.Decimal(0),
+    );
+    expect(totalDebits.toNumber()).toBe(totalCredits.toNumber());
+  });
+
+  test("5. Verify trial balance is balanced after all transactions", async () => {
+    const trialBalance = await JournalEntryService.getTrialBalance({
+      tenantPrisma: tp(),
+    });
+
+    const totalDebits = trialBalance.reduce(
+      (sum, l) => sum.plus(l.debitBalance),
+      new Prisma.Decimal(0),
+    );
+    const totalCredits = trialBalance.reduce(
+      (sum, l) => sum.plus(l.creditBalance),
+      new Prisma.Decimal(0),
+    );
+
+    // Self-verifying books: debits === credits
+    expect(totalDebits.toNumber()).toBe(totalCredits.toNumber());
+    // Should have meaningful balances (not all zeros)
+    expect(totalDebits.toNumber()).toBeGreaterThan(0);
+  });
+
+  test("6. Dashboard reflects billing activity", async () => {
+    // Revenue metrics
+    const revenue = await DashboardService.getRevenueMetrics(tp(), tenantId);
+    // revenueToday includes the payments made (1500 + 750 = 2250)
+    expect(revenue.revenueToday.toNumber()).toBeGreaterThanOrEqual(2250);
+
+    // Subscriber metrics
+    const subscribers = await DashboardService.getSubscriberMetrics(
+      tp(),
+      tenantId,
+    );
+    // Active count includes the registered subscriber
+    expect(subscribers.active).toBeGreaterThanOrEqual(1);
+    expect(subscribers.total).toBeGreaterThanOrEqual(1);
+  });
+});