feat: add fee workspace and polish AI presentation

modules/billing/types.test.ts

@@ -0,0 +1,75 @@
+import { describe, expect, it } from "vitest";
+
+import { createInitialBillingStatements } from "@/modules/billing/lib/presentation-data";
+import {
+  addBillingCharge,
+  addBillingPayment,
+  calculateBillingSummary,
+  getBillingStatus,
+  getStatementOutstandingCents,
+  getStatementTotalCents,
+} from "@/modules/billing/types";
+
+const referenceDate = new Date("2026-07-09T12:00:00.000Z");
+
+describe("billing calculations", () => {
+  it("derives paid, partial, pending, and overdue states from ledger activity", () => {
+    const statements = createInitialBillingStatements(referenceDate);
+
+    expect(statements.map((statement) => getBillingStatus(statement, referenceDate))).toEqual([
+      "paid",
+      "partial",
+      "pending",
+      "overdue",
+      "overdue",
+      "paid",
+    ]);
+  });
+
+  it("calculates statement and workspace totals from charges and payments", () => {
+    const statements = createInitialBillingStatements(referenceDate);
+    const summary = calculateBillingSummary(statements, referenceDate);
+    const firstStatement = statements[0];
+    expect(firstStatement).toBeDefined();
+    if (!firstStatement) {
+      return;
+    }
+
+    expect(getStatementTotalCents(firstStatement)).toBe(960000);
+    expect(summary.receivableCents).toBe(5995000);
+    expect(summary.collectedCents).toBe(2810000);
+    expect(summary.outstandingCents).toBe(3185000);
+    expect(summary.overdueCount).toBe(2);
+  });
+
+  it("updates outstanding amounts when payments and charges are appended", () => {
+    const statement = createInitialBillingStatements(referenceDate)[2];
+    expect(statement).toBeDefined();
+    if (!statement) {
+      return;
+    }
+
+    const paidStatement = addBillingPayment(statement, {
+      id: "payment-new",
+      amountCents: 200000,
+      method: "wechat",
+      paidAt: referenceDate.toISOString(),
+      reference: "WX-NEW",
+      operator: "收费员",
+      note: "",
+    });
+    expect(getStatementOutstandingCents(paidStatement)).toBe(640000);
+    expect(getBillingStatus(paidStatement, referenceDate)).toBe("partial");
+
+    const chargedStatement = addBillingCharge(paidStatement, {
+      id: "charge-new",
+      category: "生活用品",
+      description: "护理耗材",
+      quantity: 2,
+      serviceDate: referenceDate.toISOString(),
+      unitPriceCents: 5000,
+    });
+    expect(getStatementOutstandingCents(chargedStatement)).toBe(650000);
+    expect(chargedStatement.invoiceStatus).toBe("not_requested");
+  });
+});