优化: AI Chat 渲染与无障碍 + 文件查看 + 同步 IO 收口

- 渲染: 结果/过程分离(气泡只放最终结果,过程轮叙述+工具卡收进轨迹卡默认收起可展开——治『流式后正文消失』且不再 N 气泡打扰)
- 渲染 P0: v-memo 定向 dep(只有真正渲染流式块的 item 失效,其余取占位) + renderItems 桶 memo(签名覆盖全消费输入,item 引用稳定) + 指纹 watch 降为 O(1) toolEpoch
- TopBar 三处 O(n) messages computed 合并单次遍历;md 缓存改有界 LRU(除满即全清抖动);useTurnTrace 补 never 穷尽 + default;MessageItem 模板去重
- 无障碍(四批累计): 可点容器键盘化(含 role/tabindex/keydown/aria-expanded) + icon-only aria-label 约 60 处 + 装饰图标 aria-hidden + 52 个滚动容器 overscroll-behavior:contain + 设置开关聚焦可见环 + outline 零补偿站点补 :focus-visible
- UX 走查项: 灵感 IDEA-10/11、知识 KNOW-6/7/9、项目详情 O8、审计 SA-4、设置 SA-6/26/27/28(脏表单/冗余 save/clamp/删除二次确认)
- 文件查看专项: 切工程状态残留 F5/F6、FileTree 去重与展开反馈 F7/F15/F17、切文件头部残留 F18、R 状态着色 F19;FilePreview diff 文件头(---/+++)误当增删渲染修复 + 大纲行高亮死样式修复 + 图片失败文案 i18n 化
- 同步 IO 收口(异步上下文内阻塞): unattended 看板读写改 tokio::fs、fetch_url 探活改 spawn_blocking、http/generate_image 清理改 tokio::fs
- 子代理 P3 批量: 任务书钉扎上限/截断文案区分父子语境/环境画像日期/temperature 可覆盖/model 回退上报/lang 透传
- crate 清理: df-execute·df-types 注释与格式、df-ideas 过时注释、df-nodes subflow 夸大描述、df-project 死变量

src/views/Tasks.vue

@@ -17,7 +17,7 @@
     <!-- 错误条:消费 store.error(对齐 Knowledge/Projects error-banner,不整表替换列表) -->
     <div v-if="store.error" class="error-banner" style="margin-bottom: var(--df-gap-page)">
       <span class="error-text">{{ store.error }}</span>
-      <button class="error-dismiss" @click="store.clearError()">✕</button>
+      <button class="error-dismiss" @click="store.clearError()" :aria-label="$t('common.close')">✕</button>
     </div>
 
     <!-- 筛选栏(紧凑下拉) -->
@@ -91,7 +91,15 @@
           class="task-group"
           :class="{ collapsed: collapsedGroups.has(group.projectName) }"
         >
-          <div class="group-header" @click="toggleGroup(group.projectName)">
+          <div
+            class="group-header"
+            role="button"
+            tabindex="0"
+            :aria-expanded="!collapsedGroups.has(group.projectName)"
+            @click="toggleGroup(group.projectName)"
+            @keydown.enter.prevent="toggleGroup(group.projectName)"
+            @keydown.space.prevent="toggleGroup(group.projectName)"
+          >
             <span class="group-chevron">{{ collapsedGroups.has(group.projectName) ? '▸' : '▾' }}</span>
             <span class="group-icon">{{ group.icon }}</span>
             <h2 class="group-name">{{ group.projectName }}</h2>
@@ -140,7 +148,7 @@
                 </div>
                 <div class="task-actions">
                   <span class="status-tag" :class="taskStatusClass(row.task.status)">{{ $t(statusLabel(row.task.status)) }}</span>
-                  <button class="task-quick-btn" :title="$t('tasks.quickActions')" @click.stop="toggleQuickMenu(row.task.id)">⚙️</button>
+                  <button class="task-quick-btn" :title="$t('tasks.quickActions')" :aria-label="$t('tasks.quickActions')" @click.stop="toggleQuickMenu(row.task.id)">⚙️</button>
                   <div v-if="quickMenuId === row.task.id" class="quick-menu" @click.stop>
                     <div class="quick-menu-section">
                       <div class="quick-menu-label">{{ $t('tasks.quickStatus') }}</div>
@@ -197,7 +205,7 @@
                 </div>
                 <div class="task-actions">
                   <span class="status-tag" :class="taskStatusClass(child.status)">{{ $t(statusLabel(child.status)) }}</span>
-                  <button class="task-quick-btn" :title="$t('tasks.quickActions')" @click.stop="toggleQuickMenu(child.id)">⚙️</button>
+                  <button class="task-quick-btn" :title="$t('tasks.quickActions')" :aria-label="$t('tasks.quickActions')" @click.stop="toggleQuickMenu(child.id)">⚙️</button>
                   <div v-if="quickMenuId === child.id" class="quick-menu" @click.stop>
                     <div class="quick-menu-section">
                       <div class="quick-menu-label">{{ $t('tasks.quickStatus') }}</div>
@@ -245,7 +253,7 @@
                 </div>
                 <div class="task-actions">
                   <span class="status-tag" :class="taskStatusClass(row.task.status)">{{ $t(statusLabel(row.task.status)) }}</span>
-                  <button class="task-quick-btn" :title="$t('tasks.quickActions')" @click.stop="toggleQuickMenu(row.task.id)">⚙️</button>
+                  <button class="task-quick-btn" :title="$t('tasks.quickActions')" :aria-label="$t('tasks.quickActions')" @click.stop="toggleQuickMenu(row.task.id)">⚙️</button>
                   <div v-if="quickMenuId === row.task.id" class="quick-menu" @click.stop>
                     <div class="quick-menu-section">
                       <div class="quick-menu-label">{{ $t('tasks.quickStatus') }}</div>
@@ -298,7 +306,14 @@
             :title="parentIdSet.has(task.id) ? $t('tasks.kanban.parentNoDrag') : undefined"
           >
             <div class="task-card-top">
-              <span class="task-card-title" @click.stop="openDrawer(task.id)">{{ task.title }}</span>
+              <span
+                class="task-card-title"
+                role="button"
+                tabindex="0"
+                @click.stop="openDrawer(task.id)"
+                @keydown.enter.prevent="openDrawer(task.id)"
+                @keydown.space.prevent="openDrawer(task.id)"
+              >{{ task.title }}</span>
             </div>
             <div class="task-card-meta">
               <span v-if="task.parent_id" class="parent-tag" :title="parentTitle(task.parent_id)">⤷ {{ parentTitle(task.parent_id) }}</span>
@@ -1241,6 +1256,8 @@ onUnmounted(() => {
   transition: border-color 0.15s;
 }
 .filter-select:hover { border-color: var(--df-accent); }
+/* 聚焦可见环:仅 hover 有变化、聚焦态无边框变化,且 scoped 选择器特异性高于全局 :focus-visible 兜底,须就地补环 */
+.filter-select:focus-visible { outline: 2px solid var(--df-accent); outline-offset: 1px; }
 .filter-chip-group {
   display: flex;
   flex-wrap: wrap;