diff --git a/client/src/index.css b/client/src/index.css
index 5a9a93a9..881cc123 100644
--- a/client/src/index.css
+++ b/client/src/index.css
@@ -666,7 +666,7 @@
   }
 
   .workflow-action-panel {
-    @apply relative z-30 lg:sticky lg:top-20;
+    @apply relative z-30;
   }
 
   .workflow-action-bar {
diff --git a/client/src/pages/WorkflowTaskDetailPage.tsx b/client/src/pages/WorkflowTaskDetailPage.tsx
index 40b9b72c..bbca30cf 100644
--- a/client/src/pages/WorkflowTaskDetailPage.tsx
+++ b/client/src/pages/WorkflowTaskDetailPage.tsx
@@ -444,7 +444,7 @@ export function WorkflowTaskDetailPage() {
         <BusinessDetailAside>
           <BusinessDetailActionPanel
             title="处理"
-            className="workflow-action-panel lg:top-20"
+            className="workflow-action-panel"
             secondaryActions={(
               <>
                 <Button
diff --git a/client/tests/e2e/pc-detail-mobile-visual-wave3.spec.ts b/client/tests/e2e/pc-detail-mobile-visual-wave3.spec.ts
index 6c088edc..26ebe812 100644
--- a/client/tests/e2e/pc-detail-mobile-visual-wave3.spec.ts
+++ b/client/tests/e2e/pc-detail-mobile-visual-wave3.spec.ts
@@ -1159,6 +1159,8 @@ test("Wave3 PC 详情和通知中心视觉截图", async ({ page }) => {
   await expect(page.getByTestId("workflow-task-overview")).toBeVisible();
   await expect(page.getByTestId("workflow-task-overview")).toContainText("2026年5月27日 17:05");
   await expect(page.locator(".workflow-action-panel")).toHaveCSS("position", "sticky");
+  await expect(page.locator(".workflow-action-panel")).toHaveCSS("top", "96px");
+  await expect(page.locator(".workflow-action-panel")).toHaveCSS("z-index", "30");
   await page.setViewportSize({ width: 1440, height: 960 });
   await page.getByTestId("workflow-task-reimbursement-detail-link").click();
   await expect(page).toHaveURL(/\/reimbursements\/reim-wave3$/);
diff --git a/server/src/routes/paymentBatches.js b/server/src/routes/paymentBatches.js
index 4b619249..c230a14f 100644
--- a/server/src/routes/paymentBatches.js
+++ b/server/src/routes/paymentBatches.js
@@ -1675,6 +1675,12 @@ async function paymentBatchesRoutes(fastify) {
         const resultCode = error instanceof PaymentOrderXlsError
           ? error.code
           : error?.details?.status ?? error?.code ?? "export_failed";
+        if (error instanceof PaymentOrderXlsError && error.diagnostic) {
+          fastify.log.error(
+            { diagnostic: error.diagnostic, requestId: request.id },
+            "payment order generator unavailable",
+          );
+        }
         await fastify.prisma.auditLog.create({
           data: buildAuditLogData(request, {
             actorId: request.employee.id,
diff --git a/server/src/services/paymentOrderXls.js b/server/src/services/paymentOrderXls.js
index 66f59dd1..713acab0 100644
--- a/server/src/services/paymentOrderXls.js
+++ b/server/src/services/paymentOrderXls.js
@@ -4,14 +4,23 @@ const { spawnSync } = require("node:child_process");
 const { decryptStringOrThrow } = require("./crypto");
 
 class PaymentOrderXlsError extends Error {
-  constructor(code, details = {}) {
+  constructor(code, details = {}, diagnostic = null) {
     super(code);
     this.name = "PaymentOrderXlsError";
     this.code = code;
     this.details = details;
+    if (diagnostic) {
+      Object.defineProperty(this, "diagnostic", {
+        value: diagnostic,
+        enumerable: false,
+      });
+    }
   }
 }
 
+const PAYMENT_ORDER_RUNTIME_DIAGNOSTIC =
+  "BIFF8 运行时不可用：请安装 server/requirements/payment-order-biff8.txt 中的固定依赖，并通过 PAYMENT_ORDER_PYTHON_BIN 指定 Python 可执行文件。";
+
 function buildCustomerSerial(batchNo, rowNumber) {
   const serial = `${String(batchNo).trim()}-R${String(rowNumber).padStart(3, "0")}`;
   if (serial.length > 32) {
@@ -177,10 +186,13 @@ function mapTemplateProcessError(result) {
   const matched = stderr.match(/^\[payment-order-template\]\[ERROR\] ([a-z_]+)\s*$/);
   const internalCode = matched && PYTHON_ERROR_CODES.has(matched[1]) ? matched[1] : "process_failed";
   if (internalCode === "runtime_dependency_unavailable" || result?.error?.code === "ENOENT") {
-    return "payment_order_generator_unavailable";
+    return {
+      code: "payment_order_generator_unavailable",
+      diagnostic: PAYMENT_ORDER_RUNTIME_DIAGNOSTIC,
+    };
   }
-  if (internalCode.startsWith("template_")) return "payment_order_template_unavailable";
-  return "payment_order_generation_failed";
+  if (internalCode.startsWith("template_")) return { code: "payment_order_template_unavailable" };
+  return { code: "payment_order_generation_failed" };
 }
 
 function generatePaymentOrderXls(config, batch, options = {}) {
@@ -201,7 +213,8 @@ function generatePaymentOrderXls(config, batch, options = {}) {
     },
   });
   if (result.status !== 0 || result.error || !Buffer.isBuffer(result.stdout)) {
-    throw new PaymentOrderXlsError(mapTemplateProcessError(result));
+    const mappedError = mapTemplateProcessError(result);
+    throw new PaymentOrderXlsError(mappedError.code, {}, mappedError.diagnostic);
   }
   const buffer = result.stdout;
   if (buffer.length > maxBuffer || buffer.subarray(0, 8).toString("hex") !== "d0cf11e0a1b11ae1") {
diff --git a/server/tests/unit/routes/paymentBatches.reimbursement.test.js b/server/tests/unit/routes/paymentBatches.reimbursement.test.js
index 498c7346..43a57b45 100644
--- a/server/tests/unit/routes/paymentBatches.reimbursement.test.js
+++ b/server/tests/unit/routes/paymentBatches.reimbursement.test.js
@@ -2415,6 +2415,81 @@ describe("payment batch reimbursement routes", () => {
     await app.close();
   });
 
+  it("logs BIFF8 runtime guidance without exposing it in the finance API response", async () => {
+    const payerEncrypted = encryptStringOrThrow(
+      { fieldEncryptionKey: FIELD_ENCRYPTION_KEY },
+      `6217${"0".repeat(8)}1234`,
+    );
+    const payeeEncrypted = encryptStringOrThrow(
+      { fieldEncryptionKey: FIELD_ENCRYPTION_KEY },
+      SYNTHETIC_BANK_ACCOUNT,
+    );
+    const { app, tx } = await buildApp({
+      actor: {
+        id: ACTOR_ID,
+        department_id: "dept-1",
+        permissionCodes: ["payment.batch.manage", "payment.order.export"],
+        roleCodes: ["finance"],
+      },
+      batch: {
+        status: "reviewed",
+        payment_account_snapshot_json: {
+          accountName: "合成测试公司",
+          bankName: "中国建设银行",
+          bankInstitutionCode: "CCB",
+          accountNumberMasked: "6217********1234",
+          accountNumberEncrypted: payerEncrypted,
+        },
+        items: buildPaymentBatch().items.map((item) => ({
+          ...item,
+          snapshot_json: {
+            payee: {
+              name: "测试员工",
+              bankName: "中国建设银行",
+              bankInstitutionCode: "CCB",
+              bankAccountMasked: "6222********5678",
+              bankAccountEncrypted: payeeEncrypted,
+            },
+          },
+        })),
+      },
+    });
+    const logError = vi.spyOn(app.log, "error");
+    const originalPythonBin = process.env.PAYMENT_ORDER_PYTHON_BIN;
+    process.env.PAYMENT_ORDER_PYTHON_BIN = "/definitely-missing/payment-order-python";
+
+    try {
+      const response = await app.inject({
+        method: "POST",
+        url: `/api/payment-batches/${BATCH_ID}/payment-order`,
+        headers: { authorization: "Bearer test" },
+        payload: { reason: "运行时依赖负向验证" },
+      });
+      const body = response.json();
+
+      expect(response.statusCode).toBe(409);
+      expect(body.error).toEqual({
+        code: "PAYMENT_ORDER_EXPORT_BLOCKED",
+        message: "银行制单生成失败",
+        details: { reason: "payment_order_generator_unavailable" },
+      });
+      expect(response.body).not.toContain("payment-order-biff8.txt");
+      expect(response.body).not.toContain("PAYMENT_ORDER_PYTHON_BIN");
+      expect(response.body).not.toContain("definitely-missing");
+      expect(logError).toHaveBeenCalledWith(
+        expect.objectContaining({
+          diagnostic: expect.stringContaining("server/requirements/payment-order-biff8.txt"),
+        }),
+        "payment order generator unavailable",
+      );
+      expect(tx.paymentBatch.update).not.toHaveBeenCalled();
+    } finally {
+      if (originalPythonBin === undefined) delete process.env.PAYMENT_ORDER_PYTHON_BIN;
+      else process.env.PAYMENT_ORDER_PYTHON_BIN = originalPythonBin;
+      await app.close();
+    }
+  });
+
   it("does not let an admin without a finance business role export a payment order", async () => {
     const { app, tx } = await buildApp({
       actor: {
diff --git a/server/tests/unit/services/paymentOrderXls.test.js b/server/tests/unit/services/paymentOrderXls.test.js
index b6320790..194bb2be 100644
--- a/server/tests/unit/services/paymentOrderXls.test.js
+++ b/server/tests/unit/services/paymentOrderXls.test.js
@@ -88,9 +88,19 @@ describe("payment order BIFF8 generator", () => {
   });
 
   it("fails closed when the fixed Python runtime is unavailable", () => {
-    expect(() => generatePaymentOrderXls(config, buildBatch(), {
-      pythonBin: "/definitely-missing/payment-order-python",
-    })).toThrow(expect.objectContaining({ code: "payment_order_generator_unavailable" }));
+    let caught;
+    try {
+      generatePaymentOrderXls(config, buildBatch(), {
+        pythonBin: "/definitely-missing/payment-order-python",
+      });
+    } catch (error) {
+      caught = error;
+    }
+    expect(caught).toBeInstanceOf(PaymentOrderXlsError);
+    expect(caught).toMatchObject({ code: "payment_order_generator_unavailable" });
+    expect(caught.diagnostic).toContain("server/requirements/payment-order-biff8.txt");
+    expect(caught.diagnostic).toContain("PAYMENT_ORDER_PYTHON_BIN");
+    expect(JSON.stringify(caught)).not.toContain("payment-order-biff8.txt");
   });
 
   it("fails closed when the fixed Python dependencies are unavailable", () => {
@@ -102,8 +112,15 @@ describe("payment order BIFF8 generator", () => {
         "#!/bin/sh\nprintf '%s\\n' '[payment-order-template][ERROR] runtime_dependency_unavailable' >&2\nexit 70\n",
         { mode: 0o700 },
       );
-      expect(() => generatePaymentOrderXls(config, buildBatch(), { pythonBin: fakePython }))
-        .toThrow(expect.objectContaining({ code: "payment_order_generator_unavailable" }));
+      let caught;
+      try {
+        generatePaymentOrderXls(config, buildBatch(), { pythonBin: fakePython });
+      } catch (error) {
+        caught = error;
+      }
+      expect(caught).toMatchObject({ code: "payment_order_generator_unavailable" });
+      expect(caught.diagnostic).toContain("server/requirements/payment-order-biff8.txt");
+      expect(JSON.stringify(caught)).not.toContain("PAYMENT_ORDER_PYTHON_BIN");
     } finally {
       fs.rmSync(temporaryRoot, { recursive: true, force: true });
     }
diff --git a/server/tests/unit/services/paymentProcessingProgress.test.js b/server/tests/unit/services/paymentProcessingProgress.test.js
index fb032187..d6a8fe7c 100644
--- a/server/tests/unit/services/paymentProcessingProgress.test.js
+++ b/server/tests/unit/services/paymentProcessingProgress.test.js
@@ -117,6 +117,28 @@ describe("paymentProcessingProgress", () => {
       expect(assembler).not.toContain('label: "付款完成"');
     }
   });
+
+  it("keeps workflow action stacking local while the shared panel owns sticky positioning", () => {
+    const templateSource = fs.readFileSync(
+      path.resolve(__dirname, "../../../../client/src/components/patterns/BusinessDetailTemplate.tsx"),
+      "utf8",
+    );
+    const workflowSource = fs.readFileSync(
+      path.resolve(__dirname, "../../../../client/src/pages/WorkflowTaskDetailPage.tsx"),
+      "utf8",
+    );
+    const cssSource = fs.readFileSync(
+      path.resolve(__dirname, "../../../../client/src/index.css"),
+      "utf8",
+    );
+    const workflowPanelRule = cssSource.match(/\.workflow-action-panel\s*\{([^}]*)\}/)?.[1] ?? "";
+
+    expect(templateSource).toContain("detail-action-panel lg:sticky lg:top-24");
+    expect(workflowSource).toContain('className="workflow-action-panel"');
+    expect(workflowSource).not.toMatch(/className="workflow-action-panel[^"]*lg:top-/);
+    expect(workflowPanelRule).toContain("@apply relative z-30;");
+    expect(workflowPanelRule).not.toMatch(/lg:(?:sticky|top-)/);
+  });
 });
 const fs = require("node:fs");
 const path = require("node:path");