diff --git a/app/api/pay/route.ts b/app/api/pay/route.ts
index a102146..b3d62a9 100644
--- a/app/api/pay/route.ts
+++ b/app/api/pay/route.ts
@@ -15,6 +15,12 @@ function escapeAttr(s: string): string {
     .replace(/>/g, "&gt;");
 }
 
+function buildErrorHtml(errorMsg: string): string {
+  const esc = (s: string) =>
+    s.replace(/[&<>"']/g, (c) => ({ "&": "&amp;", "<": "&lt;", ">": "&gt;", '"': "&quot;", "'": "&#39;" })[c] || c);
+  return `<!DOCTYPE html><html><head><meta charset="utf-8"><meta name="viewport" content="width=device-width,initial-scale=1"><title>支付失败</title><style>body{font-family:system-ui;display:flex;flex-direction:column;align-items:center;justify-content:center;min-height:100vh;margin:0;background:#f0f4f8;}h2{color:#dc2626;margin-bottom:12px;}p{color:#64748b;margin-bottom:20px;text-align:center;padding:0 20px;}a{color:#2563eb;text-decoration:none;font-weight:500;}a:hover{text-decoration:underline;}</style></head><body><h2>支付发起失败</h2><p>${esc(errorMsg)}</p><p><a href="/">返回首页重试</a></p></body></html>`;
+}
+
 function buildPayHtml(
   payUrl: string,
   params: Record<string, unknown>,
@@ -31,8 +37,9 @@ function buildPayHtml(
     .map(([k, v]) => `<input type="hidden" name="${escapeAttr(k)}" value="${escapeAttr(v)}" />`)
     .join("\n");
   const direct = options?.directToCashier;
+  // 微信内：显示加载提示，避免 visibility:hidden 导致部分 WebView 表单提交异常
   return direct
-    ? `<!DOCTYPE html><html><head><meta charset="utf-8"><meta name="viewport" content="width=device-width,initial-scale=1"><title>支付</title><style>body{margin:0;overflow:hidden;visibility:hidden}</style></head><body><form id="f" action="${escapeAttr(payUrl)}" method="POST" enctype="application/x-www-form-urlencoded">${inputs}</form><script>document.getElementById("f").submit()</script></body></html>`
+    ? `<!DOCTYPE html><html><head><meta charset="utf-8"><meta name="viewport" content="width=device-width,initial-scale=1"><title>支付</title><style>body{font-family:system-ui;display:flex;justify-content:center;align-items:center;min-height:100vh;margin:0;background:#f0f4f8;}p{color:#64748b;}</style></head><body><p>正在跳转至微信支付...</p><form id="f" action="${escapeAttr(payUrl)}" method="POST" enctype="application/x-www-form-urlencoded">${inputs}</form><script>document.getElementById("f").submit()</script></body></html>`
     : `<!DOCTYPE html>
 <html>
 <head>
@@ -120,6 +127,12 @@ export async function POST(request: NextRequest) {
     const device = String(body?.device || "pc");
 
     if (!user_id) {
+      if (wantHtml) {
+        return new NextResponse(buildErrorHtml("缺少 user_id"), {
+          status: 400,
+          headers: { "Content-Type": "text/html; charset=utf-8" },
+        });
+      }
       return NextResponse.json({ ok: false, error: "缺少 user_id" }, { status: 400 });
     }
 
@@ -152,6 +165,12 @@ export async function POST(request: NextRequest) {
     );
 
     if (!params || Object.keys(params).length === 0) {
+      if (wantHtml) {
+        return new NextResponse(buildErrorHtml("支付参数为空"), {
+          status: 500,
+          headers: { "Content-Type": "text/html; charset=utf-8" },
+        });
+      }
       return NextResponse.json({ ok: false, error: "支付参数为空" }, { status: 500 });
     }
 
@@ -262,13 +281,24 @@ export async function POST(request: NextRequest) {
     }
 
     if (redirectRes.status === 400 || redirectRes.status === 500) {
-      return NextResponse.json(
-        { ok: false, error: resData?.detail || resData?.msg || "支付跳转失败" },
-        { status: redirectRes.status }
-      );
+      const errMsg = resData?.detail || resData?.msg || "支付跳转失败";
+      if (wantHtml) {
+        return new NextResponse(buildErrorHtml(errMsg), {
+          status: redirectRes.status,
+          headers: { "Content-Type": "text/html; charset=utf-8" },
+        });
+      }
+      return NextResponse.json({ ok: false, error: errMsg }, { status: redirectRes.status });
     }
 
-    return NextResponse.json({ ok: false, error: "支付创建失败" }, { status: 500 });
+    const createFailMsg = "支付创建失败";
+    if (wantHtml) {
+      return new NextResponse(buildErrorHtml(createFailMsg), {
+        status: 500,
+        headers: { "Content-Type": "text/html; charset=utf-8" },
+      });
+    }
+    return NextResponse.json({ ok: false, error: createFailMsg }, { status: 500 });
   } catch (e) {
     const err = e instanceof Error ? e : new Error(String(e));
     const msg = err.message || "";
@@ -279,6 +309,15 @@ export async function POST(request: NextRequest) {
           ? "请求超时"
           : msg;
     console.error("Pay API error:", err);
-    return NextResponse.json({ ok: false, error: `支付请求失败: ${hint}` }, { status: 500 });
+    const errorMsg = `支付请求失败: ${hint}`;
+    const ct = request.headers.get("content-type") || "";
+    const isForm = ct.includes("form") || ct.includes("x-www-form-urlencoded");
+    if (isForm) {
+      return new NextResponse(buildErrorHtml(errorMsg), {
+        status: 500,
+        headers: { "Content-Type": "text/html; charset=utf-8" },
+      });
+    }
+    return NextResponse.json({ ok: false, error: errorMsg }, { status: 500 });
   }
 }
