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

.trellis/spec/hyb-oa/reimbursement-invoice-ocr.md

@@ -165,6 +165,9 @@ const ocrRan = invoice.ocr_attempts > 0
     `sellerName`.
   - `electronic_train_ticket`: `invoiceNumber`, `invoiceDate`, `totalAmount`,
     `buyerName`.
+- Railway `totalAmount` uses the first individually parseable value from
+  Tencent `Total`, then `Fare`. Parse each field before applying fallback:
+  an empty or otherwise unparseable `Total` must not block a parseable `Fare`.
 - Never invent an invoice code from an invoice number or vice versa. Known
   no-code full-VAT and railway tickets use invoice-number-only duplicate
   detection; other categories retain code-plus-number semantics.
@@ -225,6 +228,9 @@ const ocrRan = invoice.ocr_attempts > 0
 - OCR service/job tests assert category-specific required fields,
   number-only dedupe only for known no-code categories, and no retry on terminal
   errors.
+- Railway adapter tests must cover an empty `Total` with a parseable `Fare` and
+  assert that normalized `totalAmount` uses `Fare` without emitting the source
+  amount in diagnostics.
 - Cache tests seed a legacy Tencent result containing `raw` and sensitive
   fields, then assert both normal and race cache paths return and persist only
   the allow-listed shape.
@@ -251,6 +257,16 @@ const persisted = sanitizeOcrResultForPersistence("tencent", normalized);
 await prisma.ocrResult.create({ data: { result_json: persisted } });
 ```
 
+For railway amount fallback, do not choose the raw source before parsing:
+
+```js
+// Wrong: an empty string is not nullish, so it blocks Fare.
+toNumberString(info?.Total ?? info?.Fare);
+
+// Correct: only a successfully parsed Total blocks Fare.
+toNumberString(info?.Total) ?? toNumberString(info?.Fare);
+```
+
 ## Scenario: Live OCR Sample Stdin Probe
 
 ### 1. Scope / Trigger

.trellis/tasks/07-28-travel-reimbursement-guide/implement.md

@@ -47,7 +47,9 @@
 - [x] 修正 live 样票脚本：复用 `RecognizeGeneralInvoice`、按票种必填字段和安全持久化白名单，支持单 PDF 标准输入且仅输出脱敏摘要。
 - [x] 使用合成 PDF/provider 响应覆盖住宿、铁路、非 PDF、超限、缺字段和原始响应不输出，并完成本地门禁、提交和生产部署。
 - [x] 为铁路 `Total`/`Fare` 增加只含存在、类型、非空和可解析布尔值的临时诊断；证明持久化白名单丢弃诊断且 live runner 不输出真实值。
-- [ ] 完成本地门禁、提交和生产部署后，使用剩余一次授权诊断铁路金额字段；铁路未 PASS 时仍不调用住宿样票。
+- [x] 完成本地门禁、提交和生产部署后，使用剩余一次授权诊断铁路金额字段；铁路未 PASS 时仍不调用住宿样票。
+- [ ] 修正铁路空 `Total` 阻断可解析 `Fare` 回退的问题，增加回归测试并完成提交、生产部署与运行身份复核。
+- [ ] 经新增授权复验铁路票；仅在铁路 PASS 后调用住宿票，总计最多两次腾讯 OCR 调用。
 - [ ] 经单独样票批准后分别运行住宿电子普通发票和铁路电子客票 live OCR PDF 验收。
 - [ ] 只保存脱敏状态、耗时、provider 和字段命中摘要；确认不存在 mock 调用证据。
 - [ ] 按正常 API/业务生命周期清理或归档测试记录，并执行只读残留检查。
@@ -99,6 +101,11 @@
 - 聚焦测试 19 项、完整后端 168 个文件/1075 项、Prisma validate、前端 typecheck/build、流程合同、Trellis governance、敏感内容和 diff 门禁通过；仅有既有依赖弃用提示与 22 个既有未注册文档 warning。
 - P2 聚合器的后端聚焦测试 94 项及前端门禁通过；其业务流因合成账号首次改密状态失败，live-readiness 因本地旧凭据和部署前构建标识不一致失败。进入 live OCR 步骤时已主动终止，生产最近 10 分钟新增发票和 OCR 尝试记录均为 0。
 - 诊断只存在于 provider 返回到 live runner 的进程内对象，持久化 sanitizer 丢弃整个 diagnostics；合成敏感标记未出现在序列化摘要中。
+- 诊断提交 `5f2788c` 已部署；公网构建、external deps、runtime smoke、单一 job executor、四个 timer、自动备份和新鲜度检查均通过。
+- 最后一次授权调用确认腾讯返回的铁路 `Total` 是空字符串，而 `Fare` 非空且可被当前解析器接受。现有 `info?.Total ?? info?.Fare` 在解析前选择空字符串，阻断了 `Fare` 回退；根因是适配器空字符串回退顺序，不是 PDF、凭证、网络或腾讯票种识别失败。
+- 本次仍为 `HOLD/missing_required_fields:totalAmount`，住宿样票未调用；所有既有真实 OCR 调用授权已用尽，修复后复验必须重新取得授权。
+- 已将铁路金额改为分别解析 `Total` 与 `Fare` 后回退，并增加“空 `Total` + 可解析 `Fare`”回归测试；聚焦测试 10 项、Prisma validate、流程合同、Trellis governance、敏感内容和 task validate 均通过。
+- 已在现有 OCR code-spec 固化同类字段回退规则和测试要求；本轮尚未提交、部署或调用腾讯 OCR。
 
 ## 风险文件与操作
 

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 }),