diff --git a/docs/.vitepress/theme/components/YuxiHome.vue b/docs/.vitepress/theme/components/YuxiHome.vue
index c7bbf57d..5137ea81 100644
--- a/docs/.vitepress/theme/components/YuxiHome.vue
+++ b/docs/.vitepress/theme/components/YuxiHome.vue
@@ -503,6 +503,12 @@ open http://localhost:5173</code></pre>
 .yx-home {
   --yx-max: 1152px;
   --yx-gap: 24px;
+  --yx-brand: var(--main-700);
+  --yx-brand-hover: var(--main-bright);
+  --yx-brand-soft: rgba(4, 106, 130, .12);
+  --yx-lime: #c6f43a;
+  --yx-lime-strong: #6f9300;
+  --yx-lime-soft: rgba(198, 244, 58, .24);
   color: var(--vp-c-text-1);
   font-size: 16px;
   line-height: 1.6;
@@ -513,7 +519,7 @@ open http://localhost:5173</code></pre>
   padding: 0 24px;
 }
 .yx-center { text-align: center; }
-.yx-accent { color: var(--vp-c-brand-1); }
+.yx-accent { color: var(--yx-brand); }
 
 /* 段落节奏 */
 .yx-section { padding: 96px 0; }
@@ -527,14 +533,14 @@ open http://localhost:5173</code></pre>
   font-weight: 600;
   letter-spacing: .08em;
   text-transform: uppercase;
-  color: var(--vp-c-brand-1);
+  color: var(--yx-brand);
   margin-bottom: 12px;
 }
 .yx-head__title { font-size: 34px; font-weight: 700; line-height: 1.25; margin: 0; letter-spacing: -.01em; }
 .yx-head__sub { margin: 16px auto 0; color: var(--vp-c-text-2); font-size: 17px; }
 .yx-head__sub code, .yx-quick__tip code {
   font-size: .85em; padding: 2px 6px; border-radius: 6px;
-  background: var(--vp-c-bg-alt); color: var(--vp-c-brand-1);
+  background: var(--vp-c-bg-alt); color: var(--yx-brand);
 }
 
 /* ===== Hero ===== */
@@ -546,17 +552,17 @@ open http://localhost:5173</code></pre>
 .yx-orb { position: absolute; border-radius: 50%; filter: blur(70px); will-change: transform; }
 .yx-orb--1 {
   width: 460px; height: 460px; top: -180px; right: -80px;
-  background: var(--vp-c-brand-soft); opacity: .6;
+  background: var(--yx-brand-soft); opacity: .6;
   animation: yxOrbFloat 18s ease-in-out infinite;
 }
 .yx-orb--2 {
   width: 380px; height: 380px; top: -120px; left: -120px;
-  background: var(--vp-c-brand-soft); opacity: .4;
+  background: var(--yx-lime-soft); opacity: .5;
   animation: yxOrbFloat 22s ease-in-out infinite reverse;
 }
 .yx-orb--3 {
   width: 320px; height: 320px; top: 30px; left: 46%;
-  background: var(--vp-c-brand-soft); opacity: .5;
+  background: var(--yx-brand-soft); opacity: .5;
   animation: yxOrbFloat 26s ease-in-out infinite;
 }
 .yx-grid {
@@ -592,12 +598,12 @@ open http://localhost:5173</code></pre>
   transition: transform .2s ease, background-color .2s ease, border-color .2s ease, color .2s ease;
   border: 1px solid transparent; text-decoration: none;
 }
-.yx-btn--primary { background: var(--vp-c-brand-1); color: #fff; }
-.yx-btn--primary:hover { background: var(--vp-c-brand-2); transform: translateY(-1px); }
+.yx-btn--primary { background: var(--yx-brand); color: #fff; }
+.yx-btn--primary:hover { background: var(--yx-brand-hover); transform: translateY(-1px); }
 .yx-btn--ghost { border-color: var(--vp-c-divider); color: var(--vp-c-text-1); background: var(--vp-c-bg); }
-.yx-btn--ghost:hover { border-color: var(--vp-c-brand-1); color: var(--vp-c-brand-1); }
+.yx-btn--ghost:hover { border-color: var(--yx-brand); color: var(--yx-brand); }
 .yx-btn--text { color: var(--vp-c-text-2); }
-.yx-btn--text:hover { color: var(--vp-c-brand-1); }
+.yx-btn--text:hover { color: var(--yx-brand); }
 
 .yx-hero__shot { margin-top: 56px; }
 .yx-hero__img {
@@ -627,7 +633,7 @@ open http://localhost:5173</code></pre>
 .yx-stat { text-align: center; padding: 32px 16px; }
 .yx-stat + .yx-stat { border-left: 1px solid var(--vp-c-divider); }
 .yx-stat__value {
-  font-size: 36px; font-weight: 800; color: var(--vp-c-brand-1);
+  font-size: 36px; font-weight: 800; color: var(--yx-brand);
   font-variant-numeric: tabular-nums; letter-spacing: -.02em;
 }
 .yx-stat__label { margin-top: 6px; font-size: 14px; color: var(--vp-c-text-2); }
@@ -642,12 +648,12 @@ open http://localhost:5173</code></pre>
   padding: 28px; background: var(--vp-c-bg);
   transition: transform .2s ease, border-color .2s ease;
 }
-.yx-cap:hover { transform: translateY(-3px); border-color: var(--vp-c-brand-1); }
+.yx-cap:hover { transform: translateY(-3px); border-color: var(--yx-brand); }
 .yx-cap--lg { grid-column: span 1; grid-row: span 2; display: flex; flex-direction: column; }
 .yx-cap__icon {
   display: inline-flex; align-items: center; justify-content: center;
   width: 44px; height: 44px; border-radius: 12px;
-  background: var(--vp-c-brand-soft); color: var(--vp-c-brand-1);
+  background: var(--yx-brand-soft); color: var(--yx-brand);
   margin-bottom: 18px;
 }
 .yx-cap__icon svg { width: 22px; height: 22px; }
@@ -681,9 +687,10 @@ open http://localhost:5173</code></pre>
 .yx-list__ic {
   flex: none; width: 38px; height: 38px; border-radius: 10px;
   display: inline-flex; align-items: center; justify-content: center;
-  background: var(--vp-c-brand-soft); color: var(--vp-c-brand-1);
+  background: var(--yx-brand-soft); color: var(--yx-brand);
 }
 .yx-list__ic svg { width: 20px; height: 20px; }
+.yx-tab--active .yx-list__ic { background: var(--yx-lime-soft); color: var(--yx-lime-strong); }
 .yx-tab__body { min-width: 0; }
 .yx-tab strong { display: block; font-size: 16px; }
 .yx-tab__desc {
@@ -741,7 +748,7 @@ img.yx-engine-frame { object-fit: cover; }
 /* ===== 工作原理 ===== */
 .yx-steps { display: grid; grid-template-columns: repeat(4, 1fr); gap: var(--yx-gap); }
 .yx-step { position: relative; padding: 28px 24px; border: 1px solid var(--vp-c-divider); border-radius: 16px; background: var(--vp-c-bg); }
-.yx-step__n { font-size: 26px; font-weight: 800; color: var(--vp-c-brand-1); font-variant-numeric: tabular-nums; }
+.yx-step__n { font-size: 26px; font-weight: 800; color: var(--yx-brand); font-variant-numeric: tabular-nums; }
 .yx-step__title { font-size: 17px; font-weight: 700; margin: 10px 0 8px; }
 .yx-step__desc { margin: 0; color: var(--vp-c-text-2); font-size: 14px; }
 .yx-step__arrow {
@@ -763,10 +770,10 @@ img.yx-engine-frame { object-fit: cover; }
   padding: 28px; background: var(--vp-c-bg);
   transition: transform .2s ease, border-color .2s ease;
 }
-.yx-card:hover { transform: translateY(-3px); border-color: var(--vp-c-brand-1); }
+.yx-card:hover { transform: translateY(-3px); border-color: var(--yx-brand); }
 .yx-card h3 { font-size: 18px; font-weight: 700; margin: 0 0 8px; }
 .yx-card p { margin: 0; color: var(--vp-c-text-2); font-size: 14.5px; }
-.yx-card--case { border-left: 3px solid var(--vp-c-brand-1); }
+.yx-card--case { border-left: 3px solid var(--yx-lime); }
 
 /* ===== 技术栈 ===== */
 .yx-tech { max-width: 860px; margin: 0 auto; }
@@ -796,7 +803,7 @@ img.yx-engine-frame { object-fit: cover; }
 .yx-contrib { display: block; max-width: 720px; margin: 0 auto; }
 .yx-contrib img { width: 100%; border-radius: 12px; }
 .yx-credits { margin: 32px 0 0; color: var(--vp-c-text-2); font-size: 14.5px; }
-.yx-credits a { color: var(--vp-c-brand-1); text-decoration: none; }
+.yx-credits a { color: var(--yx-brand); text-decoration: none; }
 .yx-credits a:hover { text-decoration: underline; }
 
 /* ===== 最终 CTA ===== */
diff --git a/docs/develop-guides/changelog.md b/docs/develop-guides/changelog.md
index f1646afd..c026ffca 100644
--- a/docs/develop-guides/changelog.md
+++ b/docs/develop-guides/changelog.md
@@ -24,6 +24,7 @@
 - 收敛 MCP 创建与编辑入口：前端移除整段配置文本入口和模式切换器，仅保留表单字段提交；后端 MCP 创建/更新请求拒绝额外配置字段，避免绕过表单约束。
 - 调整内置 MCP 默认项：移除 `sequentialthinking` 的系统内置同步，启动同步时清理历史系统内置记录，保留用户手动创建的同名 MCP。
 - 图片生成能力迁移为 Skill：Qwen-Image 从内置 Python 生成工具迁移到内置 Skill `image-gen`，模型调用与图片下载在 Agent 沙盒中完成，生成结果保存到 outputs 并通过 `present_artifacts` 展示，为多图片生成模型接入复用同一产物展示链路。
+- 优化前端头像加载兜底：用户与智能体头像优先展示已配置图片，加载失败后回退到基于 ID 的 DiceBear 默认头像；离线或默认头像不可达时显示名称前两个字和稳定背景色。
 - 降低知识库路由与工具模块复杂度：示例问题生成迁移到知识库 utils，文件上传统一 100 MB 限制，URL 预处理入库路径与旧 `content_type=url` 行为收敛，并修复 uid、导出 MIME 与异常透传等路由问题。
 - 重构智能体配置语义：用户可见的 `AgentConfig` 收敛为数据库持久化的一级 `Agent`，内置 Python Agent 改为智能体后端；新增 `/api/agent` 管理与运行接口，聊天、运行任务、恢复审批和文件预览均从线程绑定的 Agent 解析运行时上下文，前端只提交 `agent_id`，并在模型配置页新增“智能体”管理页签。
 - 删除 Upload 与 LightRAG 图谱/知识库能力：知识库类型收敛为 Milvus 与 Dify，只保留 Milvus 知识库内图谱构建/展示/检索，移除独立 `/graph` 页面和默认上传图谱工具。
diff --git a/web/src/components/AccountSettingsComponent.vue b/web/src/components/AccountSettingsComponent.vue
index 1760042c..806163e9 100644
--- a/web/src/components/AccountSettingsComponent.vue
+++ b/web/src/components/AccountSettingsComponent.vue
@@ -20,9 +20,17 @@
           accept="image/*"
         >
           <div class="avatar-upload" :class="{ uploading: avatarUploading }">
-            <a-avatar :size="80" :src="avatarSrc" @error="handleAvatarError">
-              <template #icon><CircleUser :size="48" /></template>
-            </a-avatar>
+            <FallbackAvatar
+              :src="userStore.avatar"
+              :default-src="avatarDefaultSrc"
+              :name="userStore.username"
+              :seed="userStore.uid || userStore.username"
+              kind="user"
+              :size="80"
+              shape="circle"
+              :alt="userStore.username"
+              class="account-avatar"
+            />
             <div class="avatar-mask">
               <Upload v-if="!avatarUploading" :size="16" />
               <RefreshCw v-else :size="16" class="spin" />
@@ -103,8 +111,9 @@
 <script setup>
 import { computed, nextTick, reactive, ref, watch } from 'vue'
 import { message } from 'ant-design-vue'
-import { CircleUser, RefreshCw, Upload } from 'lucide-vue-next'
+import { RefreshCw, Upload } from 'lucide-vue-next'
 import ApiKeyManagementComponent from '@/components/ApiKeyManagementComponent.vue'
+import FallbackAvatar from '@/components/common/FallbackAvatar.vue'
 import { useUserStore } from '@/stores/user'
 import { generatePixelAvatar } from '@/utils/pixelAvatar'
 
@@ -115,16 +124,12 @@ const savingField = ref('')
 const editingField = ref('')
 const usernameInput = ref(null)
 const phoneInput = ref(null)
-const avatarLoadFailed = ref(false)
 const profileDraft = reactive({
   username: '',
   phone_number: ''
 })
 
-const avatarSrc = computed(() => {
-  if (userStore.avatar && !avatarLoadFailed.value) return userStore.avatar
-  return generatePixelAvatar(userStore.uid)
-})
+const avatarDefaultSrc = computed(() => (userStore.uid ? generatePixelAvatar(userStore.uid) : ''))
 
 const userRoleText = computed(() => {
   switch (userStore.userRole) {
@@ -144,13 +149,6 @@ const syncProfileDraft = () => {
   profileDraft.phone_number = userStore.phoneNumber || ''
 }
 
-const handleAvatarError = () => {
-  if (userStore.avatar && !avatarLoadFailed.value) {
-    avatarLoadFailed.value = true
-  }
-  return false
-}
-
 const refreshProfile = async () => {
   refreshing.value = true
   try {
@@ -270,7 +268,6 @@ const handleAvatarChange = async (info) => {
   try {
     avatarUploading.value = true
     await userStore.uploadAvatar(info.file.originFileObj || info.file)
-    avatarLoadFailed.value = false
     message.success('头像上传成功！')
   } catch (error) {
     console.error('头像上传失败:', error)
@@ -280,13 +277,6 @@ const handleAvatarChange = async (info) => {
   }
 }
 
-watch(
-  () => userStore.avatar,
-  () => {
-    avatarLoadFailed.value = false
-  }
-)
-
 watch(() => [userStore.username, userStore.phoneNumber], syncProfileDraft, { immediate: true })
 </script>
 
@@ -337,19 +327,10 @@ watch(() => [userStore.username, userStore.phoneNumber], syncProfileDraft, { imm
     flex: 0 0 auto;
     box-shadow: 0 2px 8px var(--shadow-2);
 
-    :deep(.ant-avatar) {
+    .account-avatar {
       width: 80px;
       height: 80px;
       border: 3px solid var(--gray-150);
-      background: var(--gray-50);
-      color: var(--gray-400);
-      display: flex;
-      align-items: center;
-      justify-content: center;
-    }
-
-    :deep(.ant-avatar-image img) {
-      object-fit: cover;
     }
 
     &:hover .avatar-mask,
diff --git a/web/src/components/AgentChatComponent.vue b/web/src/components/AgentChatComponent.vue
index e9a87df1..1ebbe5d4 100644
--- a/web/src/components/AgentChatComponent.vue
+++ b/web/src/components/AgentChatComponent.vue
@@ -400,13 +400,17 @@
                       :class="{ 'is-clickable': run.child_thread_id }"
                       @click="run.child_thread_id && openSubagentThread(run)"
                     >
-                      <img
-                        v-if="getSubagentIconSrc(run)"
+                      <FallbackAvatar
                         class="state-subagent-icon"
                         :src="getSubagentIconSrc(run)"
+                        :default-src="getSubagentDefaultIconSrc(run)"
+                        :name="getSubagentRunName(run)"
+                        :seed="run.subagent_type || getSubagentRunName(run)"
+                        kind="agent"
+                        :size="28"
+                        shape="rounded"
                         :alt="`${getSubagentRunName(run)}图标`"
                       />
-                      <span v-else class="state-subagent-icon" aria-hidden="true"></span>
                       <div class="state-list-item-body">
                         <div class="state-list-item-title state-subagent-title">
                           <span>{{ getSubagentRunName(run) }}</span>
@@ -445,6 +449,7 @@
       :child-thread-id="subagentThreadModal.childThreadId"
       :subagent-name="activeSubagentThreadName"
       :subagent-avatar="activeSubagentThreadAvatar"
+      :subagent-default-avatar="activeSubagentThreadDefaultAvatar"
     />
   </div>
 </template>
@@ -500,6 +505,7 @@ import AgentArtifactsCard from '@/components/AgentArtifactsCard.vue'
 import AgentPanel from '@/components/AgentPanel.vue'
 import AttachmentTmpUploadModal from '@/components/AttachmentTmpUploadModal.vue'
 import SubagentThreadModal from '@/components/SubagentThreadModal.vue'
+import FallbackAvatar from '@/components/common/FallbackAvatar.vue'
 import { enrichTaskToolCalls, parseToolCallArgs } from '@/components/ToolCallingResult/toolRegistry'
 import { getConversationDisplayItems } from '@/utils/messageGrouping'
 import { makeChildThreadId } from '@/utils/subagentThread'
@@ -680,9 +686,12 @@ const getSubagentAgent = (run) => {
 
 const getSubagentIconSrc = (run) => {
   const agent = getSubagentAgent(run)
-  return agent?.icon || (run?.subagent_type ? generatePixelAvatar(run.subagent_type) : '')
+  return agent?.icon || ''
 }
 
+const getSubagentDefaultIconSrc = (run) =>
+  run?.subagent_type ? generatePixelAvatar(run.subagent_type) : ''
+
 const getSubagentRunMeta = (run) => {
   const artifacts = Array.isArray(run?.artifacts) ? run.artifacts.length : 0
   return artifacts ? `${artifacts} 个产物` : run?.id || ''
@@ -902,13 +911,15 @@ const subagentThreadModal = reactive({
   open: false,
   childThreadId: '',
   subagentName: '',
-  subagentAvatar: ''
+  subagentAvatar: '',
+  subagentDefaultAvatar: ''
 })
 const openSubagentThread = (run) => {
   if (!run?.child_thread_id) return
   subagentThreadModal.childThreadId = String(run.child_thread_id)
   subagentThreadModal.subagentName = getSubagentRunName(run)
   subagentThreadModal.subagentAvatar = getSubagentIconSrc(run)
+  subagentThreadModal.subagentDefaultAvatar = getSubagentDefaultIconSrc(run)
   subagentThreadModal.open = true
 }
 const isStateSectionExpanded = (key) => !collapsedStateSections[key]
@@ -1159,6 +1170,12 @@ const activeSubagentThreadAvatar = computed(() =>
     ? getSubagentIconSrc(activeSubagentThreadRun.value) || subagentThreadModal.subagentAvatar
     : subagentThreadModal.subagentAvatar
 )
+const activeSubagentThreadDefaultAvatar = computed(() =>
+  activeSubagentThreadRun.value
+    ? getSubagentDefaultIconSrc(activeSubagentThreadRun.value) ||
+      subagentThreadModal.subagentDefaultAvatar
+    : subagentThreadModal.subagentDefaultAvatar
+)
 
 // 首次运行的子智能体：前端按后端同样的哈希推算 child_thread_id，缓存到映射里供面板/轨迹定位。
 watch(
diff --git a/web/src/components/SubagentThreadModal.vue b/web/src/components/SubagentThreadModal.vue
index 77594b1b..5a3d9af0 100644
--- a/web/src/components/SubagentThreadModal.vue
+++ b/web/src/components/SubagentThreadModal.vue
@@ -8,13 +8,17 @@
   >
     <template #title>
       <div class="subagent-thread-modal-title">
-        <img
-          v-if="subagentAvatar"
+        <FallbackAvatar
           class="subagent-thread-modal-avatar"
           :src="subagentAvatar"
+          :default-src="subagentDefaultAvatar"
+          :name="modalTitleName"
+          :seed="childThreadId || modalTitleName"
+          kind="agent"
+          :size="28"
+          shape="rounded"
           :alt="`${modalTitleName} icon`"
         />
-        <span v-else class="subagent-thread-modal-avatar" aria-hidden="true"></span>
         <span class="subagent-thread-modal-name">{{ modalTitleName }}</span>
       </div>
     </template>
@@ -31,6 +35,7 @@ import { computed, ref, watch } from 'vue'
 import { agentApi } from '@/apis'
 import { MessageProcessor } from '@/utils/messageProcessor'
 import ThreadMessageList from '@/components/ThreadMessageList.vue'
+import FallbackAvatar from '@/components/common/FallbackAvatar.vue'
 
 const props = defineProps({
   open: {
@@ -48,6 +53,10 @@ const props = defineProps({
   subagentAvatar: {
     type: String,
     default: ''
+  },
+  subagentDefaultAvatar: {
+    type: String,
+    default: ''
   }
 })
 
diff --git a/web/src/components/UserInfoComponent.vue b/web/src/components/UserInfoComponent.vue
index 2064fa34..aef5ec48 100644
--- a/web/src/components/UserInfoComponent.vue
+++ b/web/src/components/UserInfoComponent.vue
@@ -3,14 +3,17 @@
     <a-dropdown :trigger="['click']" v-if="userStore.isLoggedIn">
       <div class="user-info-dropdown" :data-align="showRole ? 'left' : 'center'">
         <div class="user-avatar">
-          <img
-            v-if="avatarSrc"
-            :src="avatarSrc"
+          <FallbackAvatar
+            :src="userStore.avatar"
+            :default-src="avatarDefaultSrc"
+            :name="userStore.username"
+            :seed="userStore.uid || userStore.username"
+            kind="user"
+            :size="32"
+            shape="circle"
             :alt="userStore.username"
             class="avatar-image"
-            @error="handleAvatarError"
           />
-          <CircleUser v-else />
           <!-- <div class="user-role-badge" :class="userRoleClass"></div> -->
         </div>
         <div v-if="showRole" class="user-name">{{ userStore.username }}</div>
@@ -67,14 +70,15 @@
 </template>
 
 <script setup>
-import { computed, ref, inject, useSlots, watch } from 'vue'
+import { computed, ref, inject, useSlots } from 'vue'
 import { useRouter } from 'vue-router'
 import { useUserStore } from '@/stores/user'
 import DebugComponent from '@/components/DebugComponent.vue'
 import { message } from 'ant-design-vue'
-import { CircleUser, BookOpen, Sun, Moon, LogOut, Settings, Terminal } from 'lucide-vue-next'
+import { BookOpen, Sun, Moon, LogOut, Settings, Terminal } from 'lucide-vue-next'
 import { useThemeStore } from '@/stores/theme'
 import { generatePixelAvatar } from '@/utils/pixelAvatar'
+import FallbackAvatar from '@/components/common/FallbackAvatar.vue'
 
 const router = useRouter()
 const userStore = useUserStore()
@@ -87,26 +91,7 @@ const showDebug = ref(false)
 // Inject settings modal methods
 const { openSettingsModal } = inject('settingsModal', {})
 
-const avatarLoadFailed = ref(false)
-
-// 用户头像不可用时回退到基于 UID 生成的本地像素头像。
-const avatarSrc = computed(() => {
-  if (userStore.avatar && !avatarLoadFailed.value) return userStore.avatar
-  return generatePixelAvatar(userStore.uid)
-})
-
-const handleAvatarError = () => {
-  if (userStore.avatar && !avatarLoadFailed.value) {
-    avatarLoadFailed.value = true
-  }
-}
-
-watch(
-  () => userStore.avatar,
-  () => {
-    avatarLoadFailed.value = false
-  }
-)
+const avatarDefaultSrc = computed(() => (userStore.uid ? generatePixelAvatar(userStore.uid) : ''))
 
 defineProps({
   showRole: {
diff --git a/web/src/components/UserManagementComponent.vue b/web/src/components/UserManagementComponent.vue
index 882c22d7..57770175 100644
--- a/web/src/components/UserManagementComponent.vue
+++ b/web/src/components/UserManagementComponent.vue
@@ -73,7 +73,17 @@
               <div class="card-header">
                 <div class="user-info-main">
                   <div class="user-avatar">
-                    <img :src="getUserAvatarSrc(user)" :alt="user.username" class="avatar-img" />
+                    <FallbackAvatar
+                      :src="user.avatar"
+                      :default-src="getUserDefaultAvatarSrc(user)"
+                      :name="user.username"
+                      :seed="user.uid || user.username"
+                      kind="user"
+                      :size="40"
+                      shape="circle"
+                      :alt="user.username"
+                      class="avatar-img"
+                    />
                   </div>
                   <div class="user-info-content">
                     <div class="name-tag-row">
@@ -282,6 +292,7 @@ import {
 } from 'lucide-vue-next'
 import { formatDateTime } from '@/utils/time'
 import { generatePixelAvatar } from '@/utils/pixelAvatar'
+import FallbackAvatar from '@/components/common/FallbackAvatar.vue'
 
 const userStore = useUserStore()
 
@@ -465,7 +476,7 @@ watch(
 // 格式化时间显示
 const formatTime = (timeStr) => formatDateTime(timeStr)
 
-const getUserAvatarSrc = (user) => user.avatar || generatePixelAvatar(user.uid)
+const getUserDefaultAvatarSrc = (user) => (user.uid ? generatePixelAvatar(user.uid) : '')
 
 const isUserDeleteDisabled = (user) =>
   user.id === userStore.userId ||
diff --git a/web/src/components/common/FallbackAvatar.vue b/web/src/components/common/FallbackAvatar.vue
new file mode 100644
index 00000000..d7771390
--- /dev/null
+++ b/web/src/components/common/FallbackAvatar.vue
@@ -0,0 +1,145 @@
+<template>
+  <span
+    class="fallback-avatar"
+    :class="[`fallback-avatar--${shape}`, { 'fallback-avatar--image': currentSrc }]"
+    :style="[avatarSizeStyle, fallbackStyle]"
+  >
+    <img
+      v-if="currentSrc"
+      :key="currentSrc"
+      class="fallback-avatar-image"
+      :src="currentSrc"
+      :alt="resolvedAlt"
+      @error="handleImageError"
+    />
+    <span v-else class="fallback-avatar-text" aria-hidden="true">{{ initials }}</span>
+  </span>
+</template>
+
+<script setup>
+import { computed, ref, watch } from 'vue'
+import { getAvatarFallbackStyle, getAvatarInitials } from '@/utils/pixelAvatar'
+
+const props = defineProps({
+  src: {
+    type: String,
+    default: ''
+  },
+  defaultSrc: {
+    type: String,
+    default: ''
+  },
+  name: {
+    type: String,
+    default: ''
+  },
+  seed: {
+    type: [String, Number],
+    default: ''
+  },
+  kind: {
+    type: String,
+    default: 'user',
+    validator: (value) => ['user', 'agent'].includes(value)
+  },
+  size: {
+    type: [String, Number],
+    default: 32
+  },
+  shape: {
+    type: String,
+    default: 'circle',
+    validator: (value) => ['circle', 'rounded'].includes(value)
+  },
+  alt: {
+    type: String,
+    default: ''
+  }
+})
+
+const failedImageCount = ref(0)
+
+const imageCandidates = computed(() => {
+  const candidates = [props.src, props.defaultSrc]
+    .map((value) => String(value || '').trim())
+    .filter(Boolean)
+  return [...new Set(candidates)]
+})
+
+const currentSrc = computed(() => imageCandidates.value[failedImageCount.value] || '')
+
+const initials = computed(() => getAvatarInitials(props.name, props.kind))
+
+const fallbackStyle = computed(() => getAvatarFallbackStyle(props.seed || props.name || props.kind))
+
+const avatarSizeStyle = computed(() => {
+  const size = typeof props.size === 'number' ? `${props.size}px` : props.size
+  const fontSize =
+    typeof props.size === 'number' ? `${Math.max(10, Math.floor(props.size * 0.34))}px` : '12px'
+  return {
+    '--fallback-avatar-size': size,
+    '--fallback-avatar-font-size': fontSize
+  }
+})
+
+const resolvedAlt = computed(() => props.alt || props.name || (props.kind === 'agent' ? '智能体头像' : '用户头像'))
+
+const handleImageError = () => {
+  if (failedImageCount.value < imageCandidates.value.length) {
+    failedImageCount.value += 1
+  }
+}
+
+watch(
+  () => [props.src, props.defaultSrc],
+  () => {
+    failedImageCount.value = 0
+  }
+)
+</script>
+
+<style lang="less" scoped>
+.fallback-avatar {
+  display: inline-flex;
+  align-items: center;
+  justify-content: center;
+  width: var(--fallback-avatar-size);
+  height: var(--fallback-avatar-size);
+  flex: 0 0 var(--fallback-avatar-size);
+  overflow: hidden;
+  border: 1px solid var(--gray-150);
+  color: var(--gray-0);
+  font-size: var(--fallback-avatar-font-size);
+  font-weight: 600;
+  line-height: 1;
+  text-shadow: 0 1px 2px rgba(0, 0, 0, 0.18);
+  user-select: none;
+}
+
+.fallback-avatar--circle {
+  border-radius: 50%;
+}
+
+.fallback-avatar--rounded {
+  border-radius: 7px;
+}
+
+.fallback-avatar--image {
+  background: var(--gray-0);
+}
+
+.fallback-avatar-image {
+  display: block;
+  width: 100%;
+  height: 100%;
+  object-fit: cover;
+}
+
+.fallback-avatar-text {
+  display: block;
+  max-width: 100%;
+  overflow: hidden;
+  text-align: center;
+  white-space: nowrap;
+}
+</style>
diff --git a/web/src/components/dashboard/FeedbackModalComponent.vue b/web/src/components/dashboard/FeedbackModalComponent.vue
index 19026e46..2c1baead 100644
--- a/web/src/components/dashboard/FeedbackModalComponent.vue
+++ b/web/src/components/dashboard/FeedbackModalComponent.vue
@@ -19,9 +19,17 @@
         <!-- 卡片头部：用户信息和反馈类型 -->
         <div class="card-header">
           <div class="user-info">
-            <a-avatar :src="getFeedbackAvatarSrc(feedback)" :size="32" class="user-avatar">
-              {{ feedback.username ? feedback.username.charAt(0).toUpperCase() : 'U' }}
-            </a-avatar>
+            <FallbackAvatar
+              :src="feedback.avatar"
+              :default-src="getFeedbackDefaultAvatarSrc(feedback)"
+              :name="feedback.username"
+              :seed="feedback.uid || feedback.username"
+              kind="user"
+              :size="32"
+              shape="circle"
+              :alt="feedback.username"
+              class="user-avatar"
+            />
             <div class="user-details">
               <div class="username">{{ feedback.username || '未知用户' }}</div>
             </div>
@@ -117,6 +125,7 @@ import { LikeOutlined, DislikeOutlined, ClockCircleOutlined } from '@ant-design/
 import { dashboardApi } from '@/apis/dashboard_api'
 import { formatFullDateTime } from '@/utils/time'
 import { generatePixelAvatar } from '@/utils/pixelAvatar'
+import FallbackAvatar from '@/components/common/FallbackAvatar.vue'
 
 // 常量配置
 const CONFIG = {
@@ -212,7 +221,7 @@ const loadFeedbacks = async () => {
   }
 }
 
-const getFeedbackAvatarSrc = (feedback) => feedback.avatar || generatePixelAvatar(feedback.uid)
+const getFeedbackDefaultAvatarSrc = (feedback) => (feedback.uid ? generatePixelAvatar(feedback.uid) : '')
 
 // 格式化完整日期
 const formatFullDate = (dateString) => formatFullDateTime(dateString)
diff --git a/web/src/components/model-management/AgentManagePanel.vue b/web/src/components/model-management/AgentManagePanel.vue
index e0c3f86a..bd518add 100644
--- a/web/src/components/model-management/AgentManagePanel.vue
+++ b/web/src/components/model-management/AgentManagePanel.vue
@@ -24,6 +24,7 @@ import { isBuiltinAgent, useAgentStore } from '@/stores/agent'
 import { useUserStore } from '@/stores/user'
 import PageShoulder from '@/components/shared/PageShoulder.vue'
 import InfoCard from '@/components/shared/InfoCard.vue'
+import FallbackAvatar from '@/components/common/FallbackAvatar.vue'
 import ExtensionCardGrid from '@/components/extensions/ExtensionCardGrid.vue'
 import { generatePixelAvatar } from '@/utils/pixelAvatar'
 import { MAX_IMAGE_UPLOAD_SIZE_BYTES, MAX_IMAGE_UPLOAD_SIZE_MB } from '@/utils/upload_limits'
@@ -150,16 +151,15 @@ const getAgentShareAllowedLevels = () => {
 
 const canManageAgent = (agent) => !!agent?.can_manage
 const agentModalTitle = computed(() => (editingAgentId.value ? '编辑智能体' : '新增智能体'))
-const getAgentIconSrc = (agent) => agent.icon || (agent.id ? generatePixelAvatar(agent.id) : '')
+const getAgentDefaultIconSrc = (agent) => (agent.id ? generatePixelAvatar(agent.id) : '')
 const getAgentTags = (agent) => [
   ...(!agent?.can_manage ? [{ name: '只读', color: 'default' }] : []),
   ...(agent?.backend_id ? [{ name: agent.backend_id, color: 'blue' }] : [])
 ]
-const agentPreviewIcon = computed(() => {
-  if (agentForm.icon?.trim()) return agentForm.icon.trim()
-  if (editingAgentId.value) return generatePixelAvatar(editingAgentId.value)
-  return ''
-})
+const agentPreviewDefaultIcon = computed(() =>
+  editingAgentId.value ? generatePixelAvatar(editingAgentId.value) : ''
+)
+const agentPreviewName = computed(() => agentForm.name || editingAgentId.value || '智能体')
 const selectedBackendOption = computed(() =>
   agentBackendOptions.value.find((backend) => backend.value === agentForm.backend_id)
 )
@@ -424,10 +424,15 @@ defineExpose({
             @click="canManageAgent(agent) && openEditAgentModal(agent)"
           >
             <template #icon>
-              <img
-                v-if="getAgentIconSrc(agent)"
+              <FallbackAvatar
                 class="agent-card-icon-image"
-                :src="getAgentIconSrc(agent)"
+                :src="agent.icon"
+                :default-src="getAgentDefaultIconSrc(agent)"
+                :name="agent.name || agent.id"
+                :seed="agent.id || agent.name"
+                kind="agent"
+                :size="40"
+                shape="rounded"
                 :alt="`${agent.name || '智能体'}图标`"
               />
             </template>
@@ -534,13 +539,19 @@ defineExpose({
                       class="agent-icon-upload"
                       :class="{
                         uploading: agentIconUploading,
-                        'is-empty': !agentPreviewIcon
+                        'is-empty': !agentForm.icon && !editingAgentId && !agentForm.name.trim()
                       }"
                     >
-                      <img
-                        v-if="agentPreviewIcon"
-                        :src="agentPreviewIcon"
+                      <FallbackAvatar
+                        :src="agentForm.icon"
+                        :default-src="agentPreviewDefaultIcon"
+                        :name="agentPreviewName"
+                        :seed="editingAgentId || agentForm.slug || agentForm.name"
+                        kind="agent"
+                        :size="56"
+                        shape="rounded"
                         :alt="`${agentForm.name || '智能体'}图标`"
+                        class="agent-icon-preview-avatar"
                       />
                       <div class="agent-icon-mask">
                         <RefreshCw v-if="agentIconUploading" :size="16" class="spinning" />
@@ -667,7 +678,7 @@ defineExpose({
   display: block;
   width: 100%;
   height: 100%;
-  object-fit: cover;
+  border: 0;
 }
 
 .agent-card-menu-trigger {
@@ -911,11 +922,10 @@ defineExpose({
     border-color 0.16s ease,
     box-shadow 0.16s ease;
 
-  img {
-    display: block;
+  .agent-icon-preview-avatar {
     width: 100%;
     height: 100%;
-    object-fit: cover;
+    border: 0;
   }
 
   &:hover,
diff --git a/web/src/utils/__tests__/pixelAvatar.test.js b/web/src/utils/__tests__/pixelAvatar.test.js
index 5bf2aae3..f5259dab 100644
--- a/web/src/utils/__tests__/pixelAvatar.test.js
+++ b/web/src/utils/__tests__/pixelAvatar.test.js
@@ -1,5 +1,11 @@
 import assert from 'node:assert/strict'
-import { generatePixelAvatar } from '../pixelAvatar.js'
+import {
+  AVATAR_BACKGROUND_TOKENS,
+  generatePixelAvatar,
+  getAvatarColorIndex,
+  getAvatarFallbackStyle,
+  getAvatarInitials
+} from '../pixelAvatar.js'
 
 const DICEBEAR_GLYPHS_AVATAR_BASE_URL = 'https://api.dicebear.com/10.x/glyphs/svg'
 
@@ -52,7 +58,32 @@ const run = () => {
     console.log('T5 Missing ID fails: PASS')
   }
 
-  console.log('\nAll 5 pixel avatar tests passed!')
+  {
+    assert.equal(getAvatarInitials('张三丰', 'user'), '张三', 'Chinese initials use first two chars')
+    assert.equal(getAvatarInitials('Alice', 'user'), 'Al', 'ASCII initials use first two chars')
+    assert.equal(getAvatarInitials('', 'user'), '用户', 'User fallback should be localized')
+    assert.equal(getAvatarInitials('', 'agent'), '智能', 'Agent fallback should be localized')
+    console.log('T6 Initials: PASS')
+  }
+
+  {
+    const first = getAvatarColorIndex('user-001')
+    const second = getAvatarColorIndex('user-001')
+    const third = getAvatarColorIndex('user-002')
+    assert.equal(first, second, 'Same seed should select the same fallback color')
+    assert.notEqual(first, third, 'Different seeds should be able to select different colors')
+    assert.ok(first >= 0 && first < AVATAR_BACKGROUND_TOKENS.length, 'Color index should be valid')
+    console.log('T7 Stable fallback color: PASS')
+  }
+
+  {
+    const style = getAvatarFallbackStyle('agent-001')
+    assert.equal(typeof style.background, 'string', 'Fallback style should include background')
+    assert.equal(typeof style.color, 'string', 'Fallback style should include text color')
+    console.log('T8 Fallback style: PASS')
+  }
+
+  console.log('\nAll 8 pixel avatar tests passed!')
 }
 
 run()
diff --git a/web/src/utils/pixelAvatar.js b/web/src/utils/pixelAvatar.js
index c7e2ad20..9b82886e 100644
--- a/web/src/utils/pixelAvatar.js
+++ b/web/src/utils/pixelAvatar.js
@@ -1,5 +1,13 @@
 const DICEBEAR_GLYPHS_AVATAR_BASE_URL = 'https://api.dicebear.com/10.x/glyphs/svg'
 
+export const AVATAR_BACKGROUND_TOKENS = [
+  { background: 'linear-gradient(135deg, var(--main-600), var(--color-info-500))', color: '#fff' },
+  { background: 'linear-gradient(135deg, var(--chart-palette-5), var(--chart-palette-9))', color: '#fff' },
+  { background: 'linear-gradient(135deg, var(--chart-palette-7), var(--chart-palette-3))', color: '#fff' },
+  { background: 'linear-gradient(135deg, var(--color-accent-500), var(--chart-palette-6))', color: '#fff' },
+  { background: 'linear-gradient(135deg, var(--chart-palette-4), var(--color-error-500))', color: '#fff' }
+]
+
 const normalizeSeed = (id) => {
   if (id === null || id === undefined || String(id).trim() === '') {
     throw new Error('generatePixelAvatar requires an id')
@@ -11,3 +19,22 @@ export const generatePixelAvatar = (id) => {
   const seed = normalizeSeed(id)
   return `${DICEBEAR_GLYPHS_AVATAR_BASE_URL}?seed=${encodeURIComponent(seed)}`
 }
+
+export const getAvatarInitials = (name, kind = 'user') => {
+  const fallback = kind === 'agent' ? '智能' : '用户'
+  const normalizedName = String(name || '').trim()
+  if (!normalizedName) return fallback
+  return Array.from(normalizedName).slice(0, 2).join('')
+}
+
+export const getAvatarColorIndex = (seed) => {
+  const normalizedSeed = String(seed || '').trim()
+  const value = normalizedSeed || 'avatar'
+  let hash = 0
+  for (const char of value) {
+    hash = (hash * 31 + char.codePointAt(0)) >>> 0
+  }
+  return hash % AVATAR_BACKGROUND_TOKENS.length
+}
+
+export const getAvatarFallbackStyle = (seed) => AVATAR_BACKGROUND_TOKENS[getAvatarColorIndex(seed)]
diff --git a/web/src/views/AgentView.vue b/web/src/views/AgentView.vue
index 1f66fcad..10e8d075 100644
--- a/web/src/views/AgentView.vue
+++ b/web/src/views/AgentView.vue
@@ -40,13 +40,17 @@
                     }"
                     @click="handleAgentSwitch(agent.value, hasActiveThread)"
                   >
-                    <img
-                      v-if="agent.icon"
+                    <FallbackAvatar
                       class="config-dropdown-item-icon-image"
                       :src="agent.icon"
+                      :default-src="agent.defaultIcon"
+                      :name="agent.label"
+                      :seed="agent.value || agent.label"
+                      kind="agent"
+                      :size="24"
+                      shape="rounded"
                       :alt="`${agent.label}图标`"
                     />
-                    <span v-else class="config-dropdown-item-icon-empty" aria-hidden="true"></span>
                     <span class="config-dropdown-item-label">{{ agent.label }}</span>
                     <span v-if="agent.isBuiltin" class="config-dropdown-item-badge">内置</span>
                     <Check
@@ -103,6 +107,7 @@ import AgentChatComponent from '@/components/AgentChatComponent.vue'
 import { isBuiltinAgent, useAgentStore } from '@/stores/agent'
 import { handleChatError } from '@/utils/errorHandler'
 import { generatePixelAvatar } from '@/utils/pixelAvatar'
+import FallbackAvatar from '@/components/common/FallbackAvatar.vue'
 
 import { storeToRefs } from 'pinia'
 
@@ -178,7 +183,8 @@ const agentQuickSwitchOptions = computed(() =>
     .map((agent) => ({
       label: agent.name || agent.id,
       value: agent.id,
-      icon: agent.icon || (agent.id ? generatePixelAvatar(agent.id) : ''),
+      icon: agent.icon || '',
+      defaultIcon: agent.id ? generatePixelAvatar(agent.id) : '',
       isBuiltin: isBuiltinAgent(agent)
     }))
 )