修复铁路OCR空金额回退（07-28-travel-reimbursement-guide）

server/src/services/ocr/tencent.js

@@ -222,7 +222,7 @@ function normalizeFullVatInvoiceInfo(info, documentSubtype) {
 
 function normalizeElectronicTrainTicket(info) {
   const taxAmount = toNumberString(info?.Tax);
-  const totalAmount = toNumberString(info?.Total ?? info?.Fare);
+  const totalAmount = toNumberString(info?.Total) ?? toNumberString(info?.Fare);
 
   return {
     ...buildBaseNormalizedResult({

server/tests/unit/services/ocr.tencent.test.js

@@ -199,6 +199,39 @@ describe("Tencent general invoice OCR", () => {
     );
   });
 
+  it("falls back to a parseable railway fare when total is an empty string", () => {
+    const normalized = normalizeGeneralInvoiceResult({
+      MixedInvoiceItems: [
+        buildInvoiceItem("ElectronicTrainTicketFull", "ElectronicTrainTicketFull", {
+          Number: "251234",
+          Date: "2026-07-26",
+          Total: "",
+          Fare: "￥100.00",
+          Buyer: "合成公司",
+        }),
+      ],
+    });
+
+    expect(normalized.totalAmount).toBe("100.00");
+    expect(normalized.diagnostics.trainAmountFields).toEqual({
+      total: {
+        present: true,
+        isString: true,
+        isNumber: false,
+        nonEmpty: false,
+        parseable: false,
+      },
+      fare: {
+        present: true,
+        isString: true,
+        isNumber: false,
+        nonEmpty: true,
+        parseable: true,
+      },
+    });
+    expect(buildMissingRequiredOcrError("vat", normalized)).toBeNull();
+  });
+
   it("returns safe terminal quality results for zero, multiple and unsupported invoices", () => {
     expect(normalizeGeneralInvoiceResult({ MixedInvoiceItems: [] })).toEqual(
       expect.objectContaining({ qualityError: "invoice_not_detected", documentCount: 0 }),