Verify checkout rendering from the installed app

.github/scripts/windows_smoke_suite.ps1

@@ -16,6 +16,8 @@ param(
   [switch]$ForceFullTunnel,
   [switch]$RunSplitTunnelWebsiteSmoke,
   [switch]$RunConfigUrlSmoke,
+  [switch]$RunPaymentCheckoutSmoke,
+  [string]$PaymentSmokeArtifactDirectory = "build/windows-payment-checkout-smoke",
   [switch]$UseInstaller
 )
 
@@ -365,6 +367,21 @@ try {
         -ForceFullTunnel:$ForceFullTunnel
     }
   }
+
+  if ($RunPaymentCheckoutSmoke) {
+    if (-not $UseInstaller) {
+      throw "The payment checkout smoke requires the generated installer"
+    }
+    Write-Step "Running installed Windows payment checkout smoke tests"
+    & "$PSScriptRoot/windows_payment_checkout_smoke.ps1" `
+      -ServiceName $ServiceName `
+      -ArtifactDirectory $PaymentSmokeArtifactDirectory
+    if ($LASTEXITCODE -ne 0) {
+      throw "Windows payment checkout smoke failed with exit code $LASTEXITCODE"
+    }
+  } else {
+    Write-Step "Skipping installed Windows payment checkout smoke tests."
+  }
 }
 finally {
   try {

.github/workflows/app-smoke-tests.yml

@@ -27,6 +27,11 @@ on:
         required: false
         type: boolean
         default: true
+      windows_payment_checkout_smoke:
+        description: "Render staging Stripe and Shepherd checkout in the installed Windows app"
+        required: false
+        type: boolean
+        default: true
       macos_connect_smoke:
         description: "Include macOS connect/disconnect smoke when platforms=all (requires self-hosted runner with approved system extension)"
         required: false
@@ -145,6 +150,7 @@ jobs:
       skip_signing: true
       enable_ip_check: ${{ inputs.enable_ip_check }}
       run_connect_smoke: ${{ inputs.windows_connect_smoke }}
+      run_payment_checkout_smoke: ${{ inputs.windows_payment_checkout_smoke }}
       run_split_tunnel_website_smoke: ${{ inputs.windows_split_tunnel_website_smoke }}
       run_config_url_smoke: false
       force_full_tunnel_smoke: ${{ inputs.force_full_tunnel_smoke }}

.github/workflows/build-windows.yml

@@ -34,6 +34,11 @@ on:
         required: false
         type: boolean
         default: true
+      run_payment_checkout_smoke:
+        description: "Run installed-app staging payment checkout smoke tests"
+        required: false
+        type: boolean
+        default: false
       run_split_tunnel_website_smoke:
         description: "Run website split tunneling smoke test"
         required: false
@@ -302,16 +307,27 @@ jobs:
           $forceFullTunnelSmoke = "${{ inputs.force_full_tunnel_smoke }}" -eq "true"
           $enableIpCheck = "${{ inputs.enable_ip_check }}" -eq "true"
           $runConnectSmoke = "${{ inputs.run_connect_smoke }}" -eq "true"
-          Write-Host "Windows smoke options: connect=$runConnectSmoke splitTunnelWebsite=$runSplitTunnelWebsiteSmoke configUrl=$runConfigUrlSmoke forceFullTunnel=$forceFullTunnelSmoke ipCheck=$enableIpCheck"
+          $runPaymentCheckoutSmoke = "${{ inputs.run_payment_checkout_smoke }}" -eq "true"
+          Write-Host "Windows smoke options: connect=$runConnectSmoke paymentCheckout=$runPaymentCheckoutSmoke splitTunnelWebsite=$runSplitTunnelWebsiteSmoke configUrl=$runConfigUrlSmoke forceFullTunnel=$forceFullTunnelSmoke ipCheck=$enableIpCheck"
           ./.github/scripts/windows_smoke_suite.ps1 `
             -UseInstaller `
             -InstallerPath $installerPath `
             -RunConnectSmoke:$runConnectSmoke `
+            -RunPaymentCheckoutSmoke:$runPaymentCheckoutSmoke `
             -RunSplitTunnelWebsiteSmoke:$runSplitTunnelWebsiteSmoke `
             -RunConfigUrlSmoke:$runConfigUrlSmoke `
             -EnableIpCheck:$enableIpCheck `
             -ForceFullTunnel:$forceFullTunnelSmoke
 
+      - name: Upload Windows payment checkout smoke artifacts
+        if: ${{ always() && inputs.run_payment_checkout_smoke }}
+        uses: actions/upload-artifact@v4
+        with:
+          name: windows-payment-checkout-smoke
+          path: build/windows-payment-checkout-smoke
+          if-no-files-found: warn
+          retention-days: 7
+
       # Transitional fallback kept in place while the auth + connect smoke suite stabilizes.
       - name: Windows UI auth smoke integration
         if: ${{ inputs.run_auth_smoke }}

go.mod

@@ -25,7 +25,7 @@ replace github.com/quic-go/qpack => github.com/quic-go/qpack v0.5.1
 require (
 	github.com/alecthomas/assert/v2 v2.3.0
 	github.com/getlantern/lantern-server-provisioner v0.0.0-20251031121934-8ea031fccfa9
-	github.com/getlantern/radiance v0.0.0-20260730161730-76fcac0ceebb
+	github.com/getlantern/radiance v0.0.0-20260724161730-2ef18c71ad81
 	github.com/sagernet/sing-box v1.12.22
 	golang.org/x/mobile v0.0.0-20250711185624-d5bb5ecc55c0
 	golang.org/x/sys v0.45.0

go.sum

@@ -259,8 +259,8 @@ github.com/getlantern/pluriconfig v0.0.0-20251126214241-8cc8bc561535 h1:rtDmW8YL
 github.com/getlantern/pluriconfig v0.0.0-20251126214241-8cc8bc561535/go.mod h1:WKJEdjMOD4IuTRYwjQHjT4bmqDl5J82RShMLxPAvi0Q=
 github.com/getlantern/publicip v0.0.0-20260328175246-2c460fe80c6b h1:gMYJzEhLrmIqQ+JnjiYNm+UyUDalK3WUmVyecFwmV5g=
 github.com/getlantern/publicip v0.0.0-20260328175246-2c460fe80c6b/go.mod h1:NpfXdK4ldEKkjQ4P1R+DBF4ua5VFOlxmgHROTnYrApg=
-github.com/getlantern/radiance v0.0.0-20260730161730-76fcac0ceebb h1:1VhnolDkNBFI7LmG6IAHgabJKrR7/B8LOYLFEne5wuo=
-github.com/getlantern/radiance v0.0.0-20260730161730-76fcac0ceebb/go.mod h1:BUKzQxV+sKuRySBLPTVHDt1XkPqoIdx/G+pB9euO4LQ=
+github.com/getlantern/radiance v0.0.0-20260724161730-2ef18c71ad81 h1:goJj8l9quR8bi4A4UGewR0l+euUSUAuEnFEKmLMYtE4=
+github.com/getlantern/radiance v0.0.0-20260724161730-2ef18c71ad81/go.mod h1:3ioylshJuvd1dJEUydJvIWjSXllphapzDk8HQgiyPnc=
 github.com/getlantern/samizdat v0.0.3-0.20260724223841-a5ee9ab56830 h1:RZd3CELOtQUEzIE5kPdEO9HYg+7JYbR3OTdC+3P/wng=
 github.com/getlantern/samizdat v0.0.3-0.20260724223841-a5ee9ab56830/go.mod h1:uEeykQSW2/6rTjfPlj3MTTo59poSHXfAHTGgzYDkbr0=
 github.com/getlantern/semconv v0.0.0-20260327040646-21845dda05cb h1:c5YM7b3a4r2J8Eh89KkI6M/iTFe6Bi+b8AJlfkKdFq4=

ios/Tunnel/SingBox/ExtensionProvider.swift

@@ -110,7 +110,7 @@ class ExtensionProvider: NEPacketTunnelProvider {
     opts.dataDir = FilePath.dataDirectory.relativePath
     opts.logDir = FilePath.logsDirectory.relativePath
     // Intentionally left empty. The app and extension don't share a keychain access
-    // Radiance resolves the device ID from the main app process. 
+    // Radiance resolves the device ID from the main app process.
     opts.deviceid = ""
     opts.logLevel = "trace"
     opts.locale = Locale.current.identifier

lib/core/smoke/payment_checkout_smoke.dart

@@ -0,0 +1,67 @@
+/// Command-line settings for the Windows checkout smoke.
+class PaymentCheckoutSmokeConfig {
+  static const _providerPrefix = '--payment-checkout-smoke=';
+  static const _runIDPrefix = '--payment-checkout-run-id=';
+  static final _runIDPattern = RegExp(
+    r'^[0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[1-5][0-9a-fA-F]{3}-'
+    r'[89abAB][0-9a-fA-F]{3}-[0-9a-fA-F]{12}$',
+  );
+
+  final String provider;
+  final String runID;
+
+  const PaymentCheckoutSmokeConfig({
+    required this.provider,
+    required this.runID,
+  });
+
+  String get email => 'e2e+$runID@getlantern.org';
+
+  static PaymentCheckoutSmokeConfig? parse(
+    List<String> arguments, {
+    required bool isWindows,
+    required String buildType,
+  }) {
+    final providerArgument = _singleArgument(arguments, _providerPrefix);
+    final runIDArgument = _singleArgument(arguments, _runIDPrefix);
+
+    if (providerArgument == null && runIDArgument == null) {
+      return null;
+    }
+    if (!isWindows || buildType != 'nightly') {
+      throw const FormatException(
+        'Payment checkout smoke mode is available only in Windows nightly builds',
+      );
+    }
+    if (providerArgument == null || runIDArgument == null) {
+      throw const FormatException(
+        'Payment checkout smoke mode requires a provider and run ID',
+      );
+    }
+
+    final provider = providerArgument.toLowerCase();
+    if (provider != 'stripe' && provider != 'shepherd') {
+      throw FormatException('Unsupported payment checkout provider: $provider');
+    }
+    if (!_runIDPattern.hasMatch(runIDArgument)) {
+      throw const FormatException('Invalid payment checkout smoke run ID');
+    }
+
+    return PaymentCheckoutSmokeConfig(provider: provider, runID: runIDArgument);
+  }
+
+  static String? _singleArgument(List<String> arguments, String prefix) {
+    final matches = arguments.where((argument) => argument.startsWith(prefix));
+    if (matches.length > 1) {
+      throw FormatException('Argument may be specified only once: $prefix');
+    }
+    if (matches.isEmpty) {
+      return null;
+    }
+    final value = matches.single.substring(prefix.length).trim();
+    if (value.isEmpty) {
+      throw FormatException('Argument requires a value: $prefix');
+    }
+    return value;
+  }
+}

lib/core/widgets/app_webview.dart

@@ -100,7 +100,10 @@ class _InnerWebViewState extends ConsumerState<_InnerWebView> {
       shouldOverrideUrlLoading: shouldOverrideUrlLoading,
       initialUrlRequest: _initialRequest,
       initialSettings: setting,
-      onWebViewCreated: (controller) {},
+      onWebViewCreated: (_) {
+        final uri = Uri.tryParse(widget.url);
+        _logSmokeEvent('created', uri);
+      },
       onCreateWindow: (controller, createWindowAction) async {
         final req = createWindowAction.request;
         if (PlatformUtils.isWindows) {
@@ -120,29 +123,92 @@ class _InnerWebViewState extends ConsumerState<_InnerWebView> {
         return false;
       },
       onLoadStart: (_, webUri) async {
-        // Handle load start
         final loading = ref.read(webViewLoadingProvider.notifier);
         loading.start();
+        _logSmokeEvent(
+          'load_start',
+          webUri == null ? null : Uri.tryParse(webUri.toString()),
+        );
       },
       onLoadStop: (controller, webUri) async {
-        // Handle load stop
         ref.read(webViewLoadingProvider.notifier).stop();
-        await _handleCompletionUrl(
-          webUri == null ? null : Uri.tryParse(webUri.toString()),
+        final uri = webUri == null ? null : Uri.tryParse(webUri.toString());
+        var documentLength = -1;
+        try {
+          final rawLength = await controller.evaluateJavascript(
+            source:
+                "(document.documentElement && document.documentElement.outerHTML || '').length",
+          );
+          final parsedLength = rawLength is num
+              ? rawLength.toInt()
+              : int.tryParse(rawLength.toString());
+          if (parsedLength == null) {
+            _logSmokeEvent(
+              'document_error',
+              uri,
+              detail: 'reason=invalid_document_length',
+            );
+          } else {
+            documentLength = parsedLength;
+          }
+        } catch (_) {
+          _logSmokeEvent(
+            'document_error',
+            uri,
+            detail: 'reason=evaluate_javascript_failed',
+          );
+        }
+        _logSmokeEvent(
+          'load_stop',
+          uri,
+          detail: 'document_length=$documentLength',
         );
+        await _handleCompletionUrl(uri);
       },
       onReceivedError: (_, webResourceRequest, error) async {
-        // Handle received error
-        appLogger.error("Received error: $error");
-        // Handle load stop
-        ref.read(webViewLoadingProvider.notifier).stop();
-        await _handleCompletionUrl(
+        final uri = Uri.tryParse(webResourceRequest.url.toString());
+        final isMainFrame = webResourceRequest.isForMainFrame == true;
+        appLogger.error(
+          'WebView request failed: type=${error.type} '
+          'main_frame=$isMainFrame host=${uri?.host ?? '<none>'}',
+        );
+        _logSmokeEvent(
+          isMainFrame ? 'navigation_error' : 'resource_error',
+          uri,
+          detail: 'error_type=${error.type}',
+        );
+        if (isMainFrame) {
+          ref.read(webViewLoadingProvider.notifier).stop();
+          await _handleCompletionUrl(uri);
+        }
+      },
+      onReceivedHttpError: (_, webResourceRequest, errorResponse) async {
+        if (webResourceRequest.isForMainFrame != true) return;
+        _logSmokeEvent(
+          'navigation_error',
           Uri.tryParse(webResourceRequest.url.toString()),
+          detail: 'http_status=${errorResponse.statusCode}',
         );
       },
     );
   }
 
+  void _logSmokeEvent(String event, Uri? uri, {String detail = ''}) {
+    if (!PlatformUtils.isWindows || AppBuildInfo.buildType != 'nightly') {
+      return;
+    }
+    // Checkout paths and query strings can contain session tokens. The origin
+    // is enough to prove which provider loaded without putting them in CI logs.
+    final safeUri = uri == null
+        ? '<none>'
+        : uri.replace(path: '', query: '', fragment: '').toString();
+    final suffix = detail.isEmpty ? '' : ' $detail';
+    appLogger.info(
+      'PAYMENT_WEBVIEW_SMOKE event=$event host=${uri?.host ?? '<none>'} '
+      'url=$safeUri$suffix',
+    );
+  }
+
   bool isLanternHost(String host) =>
       host == 'lantern.io' || host == 'www.lantern.io';
 

lib/features/auth/choose_payment_method.dart

@@ -476,6 +476,7 @@ class PaymentCheckoutMethods extends HookConsumerWidget {
       padding: EdgeInsets.zero,
       itemBuilder: (context, index) {
         final method = providers[index];
+        final providerName = method.providers.name.toTitleCase();
         return Padding(
           padding: const EdgeInsets.only(bottom: 16),
           child: ExpansionTile(
@@ -498,15 +499,20 @@ class PaymentCheckoutMethods extends HookConsumerWidget {
               horizontal: defaultSize,
               vertical: defaultSize,
             ),
-            title: Row(
-              children: [
-                Text(
-                  method.method.replaceAll('-', " ").toTitleCase(),
-                  style: theme.titleMedium,
-                ),
-                SizedBox(width: defaultSize),
-                LogsPath(logoPaths: method.providers.icons),
-              ],
+            title: Semantics(
+              identifier: 'payment-provider-${method.providers.name}',
+              label: '$providerName payment method',
+              excludeSemantics: true,
+              child: Row(
+                children: [
+                  Text(
+                    method.method.replaceAll('-', " ").toTitleCase(),
+                    style: theme.titleMedium,
+                  ),
+                  SizedBox(width: defaultSize),
+                  LogsPath(logoPaths: method.providers.icons),
+                ],
+              ),
             ),
             children: [
               Row(
@@ -591,14 +597,19 @@ class PaymentCheckoutMethods extends HookConsumerWidget {
                 style: theme.bodySmall!.copyWith(color: context.textDisabled),
               ),
               SizedBox(height: defaultSize),
-              PrimaryButton(
-                label: method.providers.supportSubscription
-                    ? 'subscribe'.i18n
-                    : 'checkout'.i18n,
-                enabled: !isSubmitting,
-                onPressed: () {
-                  onSubscribe.call(method);
-                },
+              Semantics(
+                identifier: 'payment-checkout-${method.providers.name}',
+                label: 'Continue with $providerName',
+                excludeSemantics: true,
+                child: PrimaryButton(
+                  label: method.providers.supportSubscription
+                      ? 'subscribe'.i18n
+                      : 'checkout'.i18n,
+                  enabled: !isSubmitting,
+                  onPressed: () {
+                    onSubscribe.call(method);
+                  },
+                ),
               ),
             ],
           ),