fix: 加固日历日期与动态错误合同（09-05-error-explainability-payment-readiness，09-08-reimbursement-payment-closeout）

server/tests/unit/routes/reimbursements.create.test.js

@@ -434,6 +434,29 @@ describe("reimbursement create enhancements", () => {
     await app.close();
   });
 
+  it.each(["reimbursementDate", "travelStartDate", "travelEndDate"])("rejects an overflowing %s before draft writes", async (field) => {
+    const { app, state, prisma } = await buildApp();
+    try {
+      const response = await app.inject({ method: "POST", url: "/api/reimbursements",
+        payload: { [field]: "2026-02-30" } });
+      expect(response.statusCode).toBe(400);
+      expect(response.json().error.details.reasonCode).toBe("reimbursement.invalid_input");
+      expect(response.json().error.details.fieldErrors[field]).toContain("invalid_calendar_date");
+      expect(prisma.$transaction).not.toHaveBeenCalled();
+      expect(state.reimbursements).toEqual([]);
+      expect(state.auditLogs).toEqual([]);
+    } finally { await app.close(); }
+  });
+
+  it.each(["2024-02-29", "2026-04-30"])("stores valid reimbursement date %s unchanged", async (reimbursementDate) => {
+    const { app, state } = await buildApp();
+    try {
+      const response = await app.inject({ method: "POST", url: "/api/reimbursements", payload: { reimbursementDate } });
+      expect(response.statusCode).toBe(200);
+      expect(state.reimbursements[0].reimbursement_date.toISOString()).toBe(`${reimbursementDate}T00:00:00.000Z`);
+    } finally { await app.close(); }
+  });
+
   it("creates reimbursement items from template", async () => {
     const { app, state } = await buildApp();