Fix mobile payment launch detection

frontend/src/components/payment/__tests__/paymentFlow.spec.ts

@@ -106,6 +106,35 @@ describe('decidePaymentLaunch', () => {
     expect(decision.recovery.resumeToken).toBe('resume-2')
   })
 
+  it('prefers redirect on mobile when both pay_url and qr_code are present', () => {
+    const decision = decidePaymentLaunch(createOrderResult({
+      pay_url: 'https://pay.example.com/mobile/session',
+      qr_code: 'https://pay.example.com/qr/session',
+    }), {
+      visibleMethod: 'alipay',
+      orderType: 'balance',
+      isMobile: true,
+    })
+
+    expect(decision.kind).toBe('redirect_waiting')
+    expect(decision.paymentState.payUrl).toBe('https://pay.example.com/mobile/session')
+    expect(decision.paymentState.qrCode).toBe('https://pay.example.com/qr/session')
+  })
+
+  it('keeps QR flow on desktop when both pay_url and qr_code are present', () => {
+    const decision = decidePaymentLaunch(createOrderResult({
+      pay_url: 'https://pay.example.com/desktop/session',
+      qr_code: 'https://pay.example.com/qr/session',
+    }), {
+      visibleMethod: 'wxpay',
+      orderType: 'balance',
+      isMobile: false,
+    })
+
+    expect(decision.kind).toBe('qr_waiting')
+    expect(decision.paymentState.qrCode).toBe('https://pay.example.com/qr/session')
+  })
+
   it('returns wechat oauth launch when backend requires in-app authorization', () => {
     const decision = decidePaymentLaunch(createOrderResult({
       result_type: 'oauth_required',

frontend/src/components/payment/paymentFlow.ts

@@ -46,6 +46,7 @@ export interface PaymentLaunchContext {
   visibleMethod: string
   orderType: OrderType
   isMobile: boolean
+  isWechatBrowser?: boolean
   now?: number
   stripePopupUrl?: string
   stripeRouteUrl?: string
@@ -159,7 +160,23 @@ export function decidePaymentLaunch(
     return { kind: 'wechat_jsapi', paymentState: baseState, recovery: baseState, jsapi: jsapiPayload }
   }
 
-  if (baseState.qrCode) {
+  const normalizedPaymentMode = baseState.paymentMode.trim().toLowerCase()
+  const prefersRedirect = normalizedPaymentMode === 'redirect'
+    || normalizedPaymentMode === 'popup'
+    || (context.isMobile && !!baseState.payUrl)
+  const prefersQr = normalizedPaymentMode === 'qrcode'
+    || normalizedPaymentMode === 'native'
+    || (!prefersRedirect && !!baseState.qrCode)
+
+  if (visibleMethod === 'wxpay' && context.isWechatBrowser && baseState.payUrl && !baseState.qrCode) {
+    return { kind: 'redirect_waiting', paymentState: baseState, recovery: baseState }
+  }
+
+  if (prefersRedirect && baseState.payUrl) {
+    return { kind: 'redirect_waiting', paymentState: baseState, recovery: baseState }
+  }
+
+  if (prefersQr && baseState.qrCode) {
     return { kind: 'qr_waiting', paymentState: baseState, recovery: baseState }
   }