优化: 工具失败视觉区分(UX-01)+旧卡自动收起增强(UX-03)

src/i18n/en/aiTool.ts

@@ -8,6 +8,9 @@ export default {
     rejectedHint: 'User rejected this action',
     // B-260616-12: tool execution slow hint (frontend fallback, no backend cancel IPC)
     executionSlow: 'Tool "{name}" is taking longer than expected, please wait…',
+    // UX-260616-01: tool execution failure marker (AR-6 keeps status=completed, red to distinguish from success)
+    executionFailed: 'Failed',
+    executionFailedHint: 'Tool execution failed, see details below',
     collapse: 'Collapse',
     expandAll: 'Expand all',
     collapseAll: 'Collapse all',