diff --git a/web/app/components/base/ui/avatar/__tests__/index.spec.tsx b/web/app/components/base/ui/avatar/__tests__/index.spec.tsx
index 8be3f8bf0f..8a384139c2 100644
--- a/web/app/components/base/ui/avatar/__tests__/index.spec.tsx
+++ b/web/app/components/base/ui/avatar/__tests__/index.spec.tsx
@@ -1,5 +1,5 @@
 import { render, screen } from '@testing-library/react'
-import { Avatar } from '..'
+import { Avatar, AvatarFallback, AvatarImage, AvatarRoot } from '..'
 
 describe('Avatar', () => {
   describe('Rendering', () => {
@@ -60,6 +60,23 @@ describe('Avatar', () => {
     })
   })
 
+  describe('Primitives', () => {
+    it('should support composed avatar usage through exported primitives', () => {
+      render(
+        <AvatarRoot size="sm" data-testid="avatar-root">
+          <AvatarImage src="https://example.com/avatar.jpg" alt="Jane Doe" />
+          <AvatarFallback size="sm" style={{ backgroundColor: 'rgb(1, 2, 3)' }}>
+            J
+          </AvatarFallback>
+        </AvatarRoot>,
+      )
+
+      expect(screen.getByTestId('avatar-root')).toHaveClass('size-6')
+      expect(screen.getByText('J')).toBeInTheDocument()
+      expect(screen.getByText('J')).toHaveStyle({ backgroundColor: 'rgb(1, 2, 3)' })
+    })
+  })
+
   describe('Edge Cases', () => {
     it('should handle empty string name gracefully', () => {
       const { container } = render(<Avatar name="" avatar={null} />)
diff --git a/web/app/components/base/ui/avatar/index.stories.tsx b/web/app/components/base/ui/avatar/index.stories.tsx
index bf4da697db..abb3c99771 100644
--- a/web/app/components/base/ui/avatar/index.stories.tsx
+++ b/web/app/components/base/ui/avatar/index.stories.tsx
@@ -1,5 +1,5 @@
 import type { Meta, StoryObj } from '@storybook/nextjs-vite'
-import { Avatar } from '.'
+import { Avatar, AvatarFallback, AvatarRoot } from '.'
 
 const meta = {
   title: 'Base/Data Display/Avatar',
@@ -84,3 +84,27 @@ export const AllFallbackSizes: Story = {
     </div>
   ),
 }
+
+export const ComposedFallback: Story = {
+  render: () => (
+    <AvatarRoot size="xl">
+      <AvatarFallback size="xl" style={{ backgroundColor: '#2563eb' }}>
+        C
+      </AvatarFallback>
+    </AvatarRoot>
+  ),
+  parameters: {
+    docs: {
+      source: {
+        language: 'tsx',
+        code: `
+<AvatarRoot size="xl">
+  <AvatarFallback size="xl" style={{ backgroundColor: '#2563eb' }}>
+    C
+  </AvatarFallback>
+</AvatarRoot>
+        `.trim(),
+      },
+    },
+  },
+}
diff --git a/web/app/components/base/ui/avatar/index.tsx b/web/app/components/base/ui/avatar/index.tsx
index b92dd7e838..a1fd392654 100644
--- a/web/app/components/base/ui/avatar/index.tsx
+++ b/web/app/components/base/ui/avatar/index.tsx
@@ -21,31 +21,18 @@ export type AvatarProps = {
   avatar: string | null
   size?: AvatarSize
   className?: string
-  textClassName?: string
-  onError?: (hasError: boolean) => void
-  backgroundColor?: string
   onLoadingStatusChange?: (status: ImageLoadingStatus) => void
 }
 
-type AvatarRootProps = React.ComponentPropsWithRef<typeof BaseAvatar.Root> & {
+export type AvatarRootProps = React.ComponentPropsWithRef<typeof BaseAvatar.Root> & {
   size?: AvatarSize
-  hasAvatar?: boolean
-  backgroundColor?: string
 }
 
-function AvatarRoot({
+export function AvatarRoot({
   size = 'md',
   className,
-  hasAvatar = false,
-  backgroundColor,
-  style,
   ...props
 }: AvatarRootProps) {
-  const resolvedStyle: React.CSSProperties = {
-    ...(backgroundColor && !hasAvatar ? { backgroundColor } : {}),
-    ...style,
-  }
-
   return (
     <BaseAvatar.Root
       className={cn(
@@ -53,45 +40,35 @@ function AvatarRoot({
         avatarSizeClasses[size].root,
         className,
       )}
-      style={resolvedStyle}
       {...props}
     />
   )
 }
 
-type AvatarFallbackProps = React.ComponentPropsWithRef<typeof BaseAvatar.Fallback> & {
+export type AvatarFallbackProps = React.ComponentPropsWithRef<typeof BaseAvatar.Fallback> & {
   size?: AvatarSize
-  textClassName?: string
 }
 
-function AvatarFallback({
+export function AvatarFallback({
   size = 'md',
-  textClassName,
   className,
-  style,
   ...props
 }: AvatarFallbackProps) {
-  const resolvedStyle: React.CSSProperties = {
-    ...style,
-  }
-
   return (
     <BaseAvatar.Fallback
       className={cn(
         'flex size-full items-center justify-center font-medium text-white',
         avatarSizeClasses[size].text,
-        textClassName,
         className,
       )}
-      style={resolvedStyle}
       {...props}
     />
   )
 }
 
-type AvatarImageProps = React.ComponentPropsWithRef<typeof BaseAvatar.Image>
+export type AvatarImageProps = React.ComponentPropsWithRef<typeof BaseAvatar.Image>
 
-function AvatarImage({
+export function AvatarImage({
   className,
   ...props
 }: AvatarImageProps) {
@@ -108,34 +85,18 @@ export const Avatar = ({
   avatar,
   size = 'md',
   className,
-  textClassName,
-  onError,
-  backgroundColor,
   onLoadingStatusChange,
 }: AvatarProps) => {
-  const handleLoadingStatusChange = (status: ImageLoadingStatus) => {
-    onLoadingStatusChange?.(status)
-    if (status === 'error')
-      onError?.(true)
-    if (status === 'loaded')
-      onError?.(false)
-  }
-
   return (
-    <AvatarRoot
-      size={size}
-      className={className}
-      backgroundColor={backgroundColor}
-      hasAvatar={Boolean(avatar)}
-    >
+    <AvatarRoot size={size} className={className}>
       {avatar && (
         <AvatarImage
           src={avatar}
           alt={name}
-          onLoadingStatusChange={handleLoadingStatusChange}
+          onLoadingStatusChange={onLoadingStatusChange}
         />
       )}
-      <AvatarFallback size={size} textClassName={textClassName}>
+      <AvatarFallback size={size}>
         {name?.[0]?.toLocaleUpperCase()}
       </AvatarFallback>
     </AvatarRoot>
diff --git a/web/app/components/base/user-avatar-list/index.tsx b/web/app/components/base/user-avatar-list/index.tsx
index 9ee2b571d5..fc2ce60572 100644
--- a/web/app/components/base/user-avatar-list/index.tsx
+++ b/web/app/components/base/user-avatar-list/index.tsx
@@ -1,7 +1,7 @@
 import type { FC } from 'react'
 import type { AvatarSize } from '@/app/components/base/ui/avatar'
 import { memo } from 'react'
-import { Avatar } from '@/app/components/base/ui/avatar'
+import { AvatarFallback, AvatarImage, AvatarRoot } from '@/app/components/base/ui/avatar'
 import { getUserColor } from '@/app/components/workflow/collaboration/utils/user-color'
 import { useAppContext } from '@/context/app-context'
 
@@ -59,13 +59,20 @@ export const UserAvatarList: FC<UserAvatarListProps> = memo(({
             className="relative"
             style={{ zIndex: visibleUsers.length - index }}
           >
-            <Avatar
-              name={user.name}
-              avatar={user.avatar_url || null}
-              size={size}
-              className="ring-2 ring-components-panel-bg"
-              backgroundColor={userColor}
-            />
+            <AvatarRoot size={size} className="ring-2 ring-components-panel-bg">
+              {user.avatar_url && (
+                <AvatarImage
+                  src={user.avatar_url}
+                  alt={user.name}
+                />
+              )}
+              <AvatarFallback
+                size={size}
+                style={userColor ? { backgroundColor: userColor } : undefined}
+              >
+                {user.name?.[0]?.toLocaleUpperCase()}
+              </AvatarFallback>
+            </AvatarRoot>
           </div>
         )
       },
diff --git a/web/app/components/workflow/comment/thread.tsx b/web/app/components/workflow/comment/thread.tsx
index 2d699d7931..21c327e8a4 100644
--- a/web/app/components/workflow/comment/thread.tsx
+++ b/web/app/components/workflow/comment/thread.tsx
@@ -8,7 +8,7 @@ import { useTranslation } from 'react-i18next'
 import { useReactFlow, useViewport } from 'reactflow'
 import Divider from '@/app/components/base/divider'
 import InlineDeleteConfirm from '@/app/components/base/inline-delete-confirm'
-import { Avatar } from '@/app/components/base/ui/avatar'
+import { Avatar, AvatarFallback, AvatarImage, AvatarRoot } from '@/app/components/base/ui/avatar'
 import {
   DropdownMenu,
   DropdownMenuContent,
@@ -124,13 +124,20 @@ const ThreadMessage: FC<{
   return (
     <div className={cn('flex gap-3 pt-1', className)}>
       <div className="shrink-0">
-        <Avatar
-          name={authorName}
-          avatar={avatarUrl || null}
-          size="sm"
-          className={cn('h-8 w-8 rounded-full')}
-          backgroundColor={userColor}
-        />
+        <AvatarRoot size="sm" className={cn('h-8 w-8 rounded-full')}>
+          {avatarUrl && (
+            <AvatarImage
+              src={avatarUrl}
+              alt={authorName}
+            />
+          )}
+          <AvatarFallback
+            size="sm"
+            style={userColor ? { backgroundColor: userColor } : undefined}
+          >
+            {authorName?.[0]?.toLocaleUpperCase()}
+          </AvatarFallback>
+        </AvatarRoot>
       </div>
       <div className="min-w-0 flex-1 pb-4 text-text-primary last:pb-0">
         <div className="flex flex-wrap items-center gap-x-2 gap-y-1">
diff --git a/web/app/components/workflow/header/online-users.tsx b/web/app/components/workflow/header/online-users.tsx
index d7a41d1a3d..895600d07a 100644
--- a/web/app/components/workflow/header/online-users.tsx
+++ b/web/app/components/workflow/header/online-users.tsx
@@ -4,7 +4,7 @@ import { ChevronDownIcon } from '@heroicons/react/20/solid'
 import { useEffect, useState } from 'react'
 import { useTranslation } from 'react-i18next'
 import { useReactFlow } from 'reactflow'
-import { Avatar } from '@/app/components/base/ui/avatar'
+import { AvatarFallback, AvatarImage, AvatarRoot } from '@/app/components/base/ui/avatar'
 import {
   Popover,
   PopoverContent,
@@ -123,6 +123,8 @@ const OnlineUsers = () => {
           {visibleUsers.map((user, index) => {
             const isCurrentUser = user.user_id === currentUserId
             const userColor = isCurrentUser ? undefined : getUserColor(user.user_id)
+            const avatarUrl = getAvatarUrl(user)
+            const displayName = user.username || fallbackUsername
             return (
               <Tooltip key={`${user.sid}-${index}`}>
                 <TooltipTrigger>
@@ -135,13 +137,20 @@ const OnlineUsers = () => {
                     style={{ zIndex: visibleUsers.length - index }}
                     onClick={() => !isCurrentUser && jumpToUserCursor(user.user_id)}
                   >
-                    <Avatar
-                      name={user.username || fallbackUsername}
-                      avatar={getAvatarUrl(user)}
-                      size="sm"
-                      className="ring-1 ring-components-panel-bg"
-                      backgroundColor={userColor}
-                    />
+                    <AvatarRoot size="sm" className="ring-1 ring-components-panel-bg">
+                      {avatarUrl && (
+                        <AvatarImage
+                          src={avatarUrl}
+                          alt={displayName}
+                        />
+                      )}
+                      <AvatarFallback
+                        size="sm"
+                        style={userColor ? { backgroundColor: userColor } : undefined}
+                      >
+                        {displayName?.[0]?.toLocaleUpperCase()}
+                      </AvatarFallback>
+                    </AvatarRoot>
                   </div>
                 </TooltipTrigger>
                 <TooltipContent
@@ -190,6 +199,8 @@ const OnlineUsers = () => {
                 {onlineUsers.map((user) => {
                   const isCurrentUser = user.user_id === currentUserId
                   const userColor = isCurrentUser ? undefined : getUserColor(user.user_id)
+                  const avatarUrl = getAvatarUrl(user)
+                  const displayName = user.username || fallbackUsername
                   return (
                     <div
                       key={user.sid}
@@ -205,12 +216,20 @@ const OnlineUsers = () => {
                       }}
                     >
                       <div className="relative">
-                        <Avatar
-                          name={user.username || fallbackUsername}
-                          avatar={getAvatarUrl(user)}
-                          size="sm"
-                          backgroundColor={userColor}
-                        />
+                        <AvatarRoot size="sm">
+                          {avatarUrl && (
+                            <AvatarImage
+                              src={avatarUrl}
+                              alt={displayName}
+                            />
+                          )}
+                          <AvatarFallback
+                            size="sm"
+                            style={userColor ? { backgroundColor: userColor } : undefined}
+                          >
+                            {displayName?.[0]?.toLocaleUpperCase()}
+                          </AvatarFallback>
+                        </AvatarRoot>
                       </div>
                       {renderDisplayName(
                         user,