diff --git a/lib/runtime/go_task_service_client.dart b/lib/runtime/go_task_service_client.dart
index d8deb780..d1c1c112 100644
--- a/lib/runtime/go_task_service_client.dart
+++ b/lib/runtime/go_task_service_client.dart
@@ -723,8 +723,8 @@ GoTaskServiceResult goTaskServiceResultFromAcpResponse(
       .map((item) => item['id']?.toString().trim() ?? '')
       .where((item) => item.isNotEmpty)
       .toList(growable: false);
+  final success = _boolValue(result['success']) ?? true;
   final fallbackFailureText = () {
-    final success = _boolValue(result['success']) ?? true;
     if (success) {
       return '';
     }
@@ -751,12 +751,20 @@ GoTaskServiceResult goTaskServiceResultFromAcpResponse(
               ? streamedText.trim()
               : '')
           .trim();
+  final directErrorMessage = result['error']?.toString().trim() ?? '';
+  final effectiveErrorMessage = success
+      ? directErrorMessage
+      : fallbackFailureText.isNotEmpty
+      ? fallbackFailureText
+      : primaryText.isNotEmpty
+      ? primaryText
+      : directErrorMessage;
   return GoTaskServiceResult(
-    success: _boolValue(result['success']) ?? true,
+    success: success,
     message: primaryText,
     turnId: result['turnId']?.toString().trim() ?? '',
     raw: result,
-    errorMessage: result['error']?.toString() ?? '',
+    errorMessage: effectiveErrorMessage,
     resolvedModel:
         result['model']?.toString().trim() ??
         result['resolvedModel']?.toString().trim() ??
diff --git a/test/runtime/gateway_acp_client_auth_test.dart b/test/runtime/gateway_acp_client_auth_test.dart
index 44e02c5e..0c467b0b 100644
--- a/test/runtime/gateway_acp_client_auth_test.dart
+++ b/test/runtime/gateway_acp_client_auth_test.dart
@@ -79,6 +79,22 @@ void main() {
 
       expect(result.success, isFalse);
       expect(result.message, 'codex returned no displayable output');
+      expect(result.errorMessage, 'codex returned no displayable output');
+    });
+
+    test('uses bridge failure message when error field is absent', () {
+      final result = goTaskServiceResultFromAcpResponse(<String, dynamic>{
+        'jsonrpc': '2.0',
+        'id': 'request-id',
+        'result': <String, dynamic>{
+          'success': false,
+          'message': 'OpenClaw gateway returned artifact_missing',
+        },
+      }, route: GoTaskServiceRoute.externalAcpSingle);
+
+      expect(result.success, isFalse);
+      expect(result.message, 'OpenClaw gateway returned artifact_missing');
+      expect(result.errorMessage, 'OpenClaw gateway returned artifact_missing');
     });
 
     test('uses unavailable message when bridge reports provider failure', () {
@@ -93,6 +109,7 @@ void main() {
 
       expect(result.success, isFalse);
       expect(result.message, 'codex execution environment is unavailable');
+      expect(result.errorMessage, 'codex execution environment is unavailable');
     });
 
     test('keeps provider failure diagnostics for empty upstream output', () {
@@ -113,6 +130,10 @@ void main() {
         result.message,
         'hermes upstream returned empty response (code: PROVIDER_EMPTY_RESPONSE, upstream: session/prompt)',
       );
+      expect(
+        result.errorMessage,
+        'hermes upstream returned empty response (code: PROVIDER_EMPTY_RESPONSE, upstream: session/prompt)',
+      );
     });
 
     test('keeps bridge message and inline artifacts together', () {