diff --git a/frontend/src/components/user/profile/ProfileAvatarCard.vue b/frontend/src/components/user/profile/ProfileAvatarCard.vue
index 357c0f27..9945f7b7 100644
--- a/frontend/src/components/user/profile/ProfileAvatarCard.vue
+++ b/frontend/src/components/user/profile/ProfileAvatarCard.vue
@@ -32,14 +32,6 @@
           </p>
         </div>
 
-        <textarea
-          data-testid="profile-avatar-input"
-          v-model="avatarDraft"
-          rows="3"
-          class="input min-h-[88px]"
-          :placeholder="t('profile.avatar.inputPlaceholder')"
-        />
-
         <div class="flex flex-wrap items-center gap-3">
           <label class="btn btn-secondary btn-sm cursor-pointer">
             <input
@@ -56,7 +48,7 @@
             data-testid="profile-avatar-save"
             type="button"
             class="btn btn-primary btn-sm"
-            :disabled="avatarSaving"
+            :disabled="avatarSaving || !avatarDraft"
             @click="handleAvatarSave"
           >
             {{ t('common.save') }}
@@ -97,7 +89,7 @@ const appStore = useAppStore()
 const targetAvatarUploadBytes = 20 * 1024
 const avatarScaleSteps = [1, 0.92, 0.84, 0.76, 0.68, 0.6, 0.52, 0.44, 0.36]
 const avatarQualitySteps = [0.92, 0.84, 0.76, 0.68, 0.6, 0.52, 0.44, 0.36]
-const avatarDraft = ref(props.user?.avatar_url?.trim() || '')
+const avatarDraft = ref('')
 const avatarSaving = ref(false)
 
 const displayName = computed(() => props.user?.username?.trim() || props.user?.email?.trim() || 'User')
@@ -106,36 +98,23 @@ const avatarPreviewUrl = computed(() => avatarDraft.value.trim() || props.user?.
 
 watch(
   () => props.user?.avatar_url,
-  (value) => {
-    avatarDraft.value = value?.trim() || ''
+  () => {
+    avatarDraft.value = ''
   }
 )
 
-function validateAvatarInput(value: string): string | null {
+function normalizeUploadedAvatar(value: string): string | null {
   const normalized = value.trim()
   if (!normalized) {
     return null
   }
 
-  if (normalized.startsWith('data:')) {
-    if (!/^data:image\/[a-zA-Z0-9.+-]+;base64,/i.test(normalized)) {
-      appStore.showError(t('profile.avatar.invalidValue'))
-      return null
-    }
-    return normalized
+  if (!/^data:image\/[a-zA-Z0-9.+-]+;base64,/i.test(normalized)) {
+    appStore.showError(t('profile.avatar.uploadRequired'))
+    return null
   }
 
-  try {
-    const parsed = new URL(normalized)
-    if (parsed.protocol === 'http:' || parsed.protocol === 'https:') {
-      return normalized
-    }
-  } catch {
-    // Invalid URL is handled below.
-  }
-
-  appStore.showError(t('profile.avatar.invalidValue'))
-  return null
+  return normalized
 }
 
 function readFileAsDataURL(file: File): Promise<string> {
@@ -226,7 +205,7 @@ async function handleAvatarFileChange(event: Event) {
   try {
     const preparedFile = await prepareAvatarUpload(file)
     const dataURL = await readFileAsDataURL(preparedFile)
-    const normalized = validateAvatarInput(dataURL)
+    const normalized = normalizeUploadedAvatar(dataURL)
     if (!normalized) {
       return
     }
@@ -237,7 +216,7 @@ async function handleAvatarFileChange(event: Event) {
 }
 
 async function handleAvatarSave() {
-  const normalized = validateAvatarInput(avatarDraft.value)
+  const normalized = normalizeUploadedAvatar(avatarDraft.value)
   if (!normalized) {
     return
   }
@@ -277,4 +256,3 @@ async function handleAvatarDelete() {
   }
 }
 </script>
-
diff --git a/frontend/src/components/user/profile/ProfileInfoCard.vue b/frontend/src/components/user/profile/ProfileInfoCard.vue
index 9c2c5ff6..d18cfbc9 100644
--- a/frontend/src/components/user/profile/ProfileInfoCard.vue
+++ b/frontend/src/components/user/profile/ProfileInfoCard.vue
@@ -50,6 +50,19 @@
         </div>
       </div>
 
+      <div
+        v-if="sourceHints.length"
+        class="mt-4 grid gap-2 rounded-2xl border border-gray-100 bg-gray-50/80 p-3 text-xs text-gray-500 dark:border-dark-700 dark:bg-dark-900/30 dark:text-gray-400"
+      >
+        <div
+          v-for="hint in sourceHints"
+          :key="hint.key"
+          class="flex items-start gap-2"
+        >
+          <Icon name="link" size="sm" class="mt-0.5 text-gray-400 dark:text-gray-500" />
+          <span>{{ hint.text }}</span>
+        </div>
+      </div>
     </div>
   </div>
 </template>
@@ -58,7 +71,7 @@
 import { computed } from 'vue'
 import { useI18n } from 'vue-i18n'
 import Icon from '@/components/icons/Icon.vue'
-import type { User } from '@/types'
+import type { User, UserAuthProvider, UserProfileSourceContext } from '@/types'
 
 const props = defineProps<{
   user: User | null
@@ -69,4 +82,108 @@ const { t } = useI18n()
 const avatarUrl = computed(() => props.user?.avatar_url?.trim() || '')
 const displayName = computed(() => props.user?.username?.trim() || props.user?.email?.trim() || 'User')
 const avatarInitial = computed(() => displayName.value.charAt(0).toUpperCase() || 'U')
+
+const providerLabels = computed<Record<UserAuthProvider, string>>(() => ({
+  email: t('profile.authBindings.providers.email'),
+  linuxdo: t('profile.authBindings.providers.linuxdo'),
+  oidc: t('profile.authBindings.providers.oidc', { providerName: 'OIDC' }),
+  wechat: t('profile.authBindings.providers.wechat')
+}))
+
+function normalizeProvider(value: string): UserAuthProvider | null {
+  const normalized = value.trim().toLowerCase()
+  if (normalized === 'email' || normalized === 'linuxdo' || normalized === 'wechat') {
+    return normalized
+  }
+  if (normalized === 'oidc' || normalized.startsWith('oidc:') || normalized.startsWith('oidc/')) {
+    return 'oidc'
+  }
+  return null
+}
+
+function readObjectString(source: Record<string, unknown>, ...keys: string[]): string {
+  for (const key of keys) {
+    const value = source[key]
+    if (typeof value === 'string' && value.trim()) {
+      return value.trim()
+    }
+  }
+  return ''
+}
+
+function resolveThirdPartySource(
+  rawSource: string | UserProfileSourceContext | null | undefined
+): { provider: UserAuthProvider; label: string } | null {
+  if (!rawSource) {
+    return null
+  }
+
+  if (typeof rawSource === 'string') {
+    const provider = normalizeProvider(rawSource)
+    if (!provider || provider === 'email') {
+      return null
+    }
+    return {
+      provider,
+      label: providerLabels.value[provider]
+    }
+  }
+
+  const sourceRecord = rawSource as Record<string, unknown>
+  const provider = normalizeProvider(
+    readObjectString(sourceRecord, 'provider', 'source', 'provider_type', 'auth_provider')
+  )
+  if (!provider || provider === 'email') {
+    return null
+  }
+
+  const explicitLabel = readObjectString(
+    sourceRecord,
+    'provider_label',
+    'label',
+    'provider_name',
+    'providerName'
+  )
+
+  return {
+    provider,
+    label: explicitLabel || providerLabels.value[provider]
+  }
+}
+
+const sourceHints = computed(() => {
+  const currentUser = props.user
+  if (!currentUser) {
+    return []
+  }
+
+  const hints: Array<{ key: string; text: string }> = []
+  const avatarSource = resolveThirdPartySource(
+    currentUser.profile_sources?.avatar ?? currentUser.avatar_source
+  )
+  const usernameSource = resolveThirdPartySource(
+    currentUser.profile_sources?.username ??
+      currentUser.profile_sources?.display_name ??
+      currentUser.profile_sources?.nickname ??
+      currentUser.display_name_source ??
+      currentUser.username_source ??
+      currentUser.nickname_source
+  )
+
+  if (avatarSource) {
+    hints.push({
+      key: 'avatar',
+      text: t('profile.authBindings.source.avatar', { providerName: avatarSource.label })
+    })
+  }
+
+  if (usernameSource) {
+    hints.push({
+      key: 'username',
+      text: t('profile.authBindings.source.username', { providerName: usernameSource.label })
+    })
+  }
+
+  return hints
+})
 </script>
diff --git a/frontend/src/components/user/profile/__tests__/ProfileAvatarCard.spec.ts b/frontend/src/components/user/profile/__tests__/ProfileAvatarCard.spec.ts
index e5f57d69..cba24960 100644
--- a/frontend/src/components/user/profile/__tests__/ProfileAvatarCard.spec.ts
+++ b/frontend/src/components/user/profile/__tests__/ProfileAvatarCard.spec.ts
@@ -88,6 +88,8 @@ function createUser(overrides: Partial<User> = {}): User {
 async function flushAsyncWork(): Promise<void> {
   await Promise.resolve()
   await Promise.resolve()
+  await Promise.resolve()
+  await Promise.resolve()
 }
 
 const originalFileReader = globalThis.FileReader
@@ -156,6 +158,23 @@ describe('ProfileAvatarCard', () => {
     vi.restoreAllMocks()
   })
 
+  it('does not render a manual avatar input field', () => {
+    authStoreState.user = createUser()
+
+    const wrapper = mount(ProfileAvatarCard, {
+      props: {
+        user: authStoreState.user
+      },
+      global: {
+        stubs: {
+          Icon: true
+        }
+      }
+    })
+
+    expect(wrapper.find('[data-testid="profile-avatar-input"]').exists()).toBe(false)
+  })
+
   it('compresses an uploaded image that exceeds the 20KB target before saving', async () => {
     installAvatarCompressionMocks()
     const updatedUser = createUser({ avatar_url: 'data:image/webp;base64,Y29tcHJlc3NlZC1hdmF0YXI=' })
diff --git a/frontend/src/components/user/profile/__tests__/ProfileInfoCard.spec.ts b/frontend/src/components/user/profile/__tests__/ProfileInfoCard.spec.ts
index 0ee9aebb..87b070a7 100644
--- a/frontend/src/components/user/profile/__tests__/ProfileInfoCard.spec.ts
+++ b/frontend/src/components/user/profile/__tests__/ProfileInfoCard.spec.ts
@@ -21,9 +21,19 @@ vi.mock('vue-i18n', async (importOriginal) => {
   return {
     ...actual,
     useI18n: () => ({
-      t: (key: string) => {
+      t: (key: string, params?: Record<string, string>) => {
         if (key === 'profile.administrator') return 'Administrator'
         if (key === 'profile.user') return 'User'
+        if (key === 'profile.authBindings.providers.email') return 'Email'
+        if (key === 'profile.authBindings.providers.linuxdo') return 'LinuxDo'
+        if (key === 'profile.authBindings.providers.wechat') return 'WeChat'
+        if (key === 'profile.authBindings.providers.oidc') return params?.providerName || 'OIDC'
+        if (key === 'profile.authBindings.source.avatar') {
+          return `Avatar synced from ${params?.providerName || 'provider'}`
+        }
+        if (key === 'profile.authBindings.source.username') {
+          return `Username synced from ${params?.providerName || 'provider'}`
+        }
         return key
       }
     })
@@ -69,4 +79,26 @@ describe('ProfileInfoCard', () => {
     expect(wrapper.find('[data-testid="profile-avatar-save"]').exists()).toBe(false)
     expect(wrapper.find('[data-testid="profile-binding-email-status"]').exists()).toBe(false)
   })
+
+  it('renders third-party source hints from profile sources', () => {
+    const wrapper = mount(ProfileInfoCard, {
+      props: {
+        user: createUser({
+          avatar_url: 'https://cdn.example.com/linuxdo.png',
+          profile_sources: {
+            avatar: { provider: 'linuxdo', source: 'linuxdo' },
+            username: { provider: 'linuxdo', source: 'linuxdo' }
+          }
+        })
+      },
+      global: {
+        stubs: {
+          Icon: true
+        }
+      }
+    })
+
+    expect(wrapper.text()).toContain('Avatar synced from LinuxDo')
+    expect(wrapper.text()).toContain('Username synced from LinuxDo')
+  })
 })
diff --git a/frontend/src/i18n/locales/en.ts b/frontend/src/i18n/locales/en.ts
index 7b37009f..b01f8f67 100644
--- a/frontend/src/i18n/locales/en.ts
+++ b/frontend/src/i18n/locales/en.ts
@@ -943,11 +943,10 @@ export default {
     },
     avatar: {
       title: 'Profile Avatar',
-      description: 'Set your avatar with a remote image URL or upload an image. Static uploads are compressed to 20KB before saving.',
-      inputLabel: 'Avatar URL or data URL',
-      inputPlaceholder: 'https://cdn.example.com/avatar.png',
+      description: 'Upload an avatar image. Static uploads are compressed to 20KB before saving.',
       uploadAction: 'Upload image',
       uploadHint: 'Static uploads are compressed to 20KB when possible. GIF uploads must already be within 20KB.',
+      uploadRequired: 'Upload an avatar image first',
       saveSuccess: 'Avatar updated',
       deleteSuccess: 'Avatar removed',
       invalidType: 'Please choose an image file',
@@ -955,7 +954,6 @@ export default {
       compressTooLarge: 'Unable to compress this image below 20KB. Try a smaller image.',
       compressFailed: 'Failed to compress the selected image.',
       readFailed: 'Failed to read the selected image.',
-      invalidValue: 'Enter a valid avatar URL or image data URL',
       emptyDeleteHint: 'Avatar is already empty',
     },
     authBindings: {
diff --git a/frontend/src/i18n/locales/zh.ts b/frontend/src/i18n/locales/zh.ts
index 97de9c9c..921fc06e 100644
--- a/frontend/src/i18n/locales/zh.ts
+++ b/frontend/src/i18n/locales/zh.ts
@@ -947,11 +947,10 @@ export default {
     },
     avatar: {
       title: '资料头像',
-      description: '支持填写远程图片 URL，或上传头像图片；静态图片会自动压缩到 20KB 以内后再保存。',
-      inputLabel: '头像 URL 或 data URL',
-      inputPlaceholder: 'https://cdn.example.com/avatar.png',
+      description: '仅支持上传头像图片；静态图片会自动压缩到 20KB 以内后再保存。',
       uploadAction: '上传图片',
       uploadHint: '上传图片时会自动压缩静态图片到 20KB 以内，GIF 需自行控制在 20KB 以内',
+      uploadRequired: '请先上传头像图片',
       saveSuccess: '头像已更新',
       deleteSuccess: '头像已删除',
       invalidType: '请选择图片文件',
@@ -959,7 +958,6 @@ export default {
       compressTooLarge: '无法将图片压缩到 20KB 以内，请换一张更小的图片',
       compressFailed: '压缩所选图片失败',
       readFailed: '读取所选图片失败',
-      invalidValue: '请输入有效的头像 URL 或图片 data URL',
       emptyDeleteHint: '当前没有可删除的头像',
     },
     authBindings: {