diff --git a/web/app/components/workflow/comment/index.tsx b/web/app/components/workflow/comment/index.tsx
index 148d5094f8..7c91b8dccb 100644
--- a/web/app/components/workflow/comment/index.tsx
+++ b/web/app/components/workflow/comment/index.tsx
@@ -2,3 +2,4 @@ export { CommentCursor } from './cursor'
 export { CommentInput } from './input'
 export { CommentIcon } from './icon'
 export { CommentThread } from './thread'
+export { MentionInput } from './mention-input'
diff --git a/web/app/components/workflow/comment/input.tsx b/web/app/components/workflow/comment/input.tsx
index ac20064839..231f13c99b 100644
--- a/web/app/components/workflow/comment/input.tsx
+++ b/web/app/components/workflow/comment/input.tsx
@@ -1,15 +1,10 @@
 import type { FC } from 'react'
-import { memo, useCallback, useEffect, useMemo, useRef, useState } from 'react'
-import { createPortal } from 'react-dom'
-import Textarea from 'react-textarea-autosize'
-import { RiSendPlane2Fill } from '@remixicon/react'
-import { useParams } from 'next/navigation'
+import { memo, useCallback, useEffect, useMemo, useState } from 'react'
 import { useReactFlow, useViewport } from 'reactflow'
-import cn from '@/utils/classnames'
-import Button from '@/app/components/base/button'
 import Avatar from '@/app/components/base/avatar'
 import { useAppContext } from '@/context/app-context'
-import { type UserProfile, fetchMentionableUsers } from '@/service/workflow-comment'
+import { MentionInput } from './mention-input'
+import cn from '@/utils/classnames'
 
 type CommentInputProps = {
   position: { x: number; y: number }
@@ -19,39 +14,14 @@ type CommentInputProps = {
 
 export const CommentInput: FC<CommentInputProps> = memo(({ position, onSubmit, onCancel }) => {
   const [content, setContent] = useState('')
-  const textareaRef = useRef<HTMLTextAreaElement>(null)
   const { userProfile } = useAppContext()
   const { flowToScreenPosition } = useReactFlow()
   const viewport = useViewport()
-  const params = useParams()
-  const appId = params.appId as string
-
-  const [mentionUsers, setMentionUsers] = useState<UserProfile[]>([])
-  const [showMentionDropdown, setShowMentionDropdown] = useState(false)
-  const [mentionQuery, setMentionQuery] = useState('')
-  const [mentionPosition, setMentionPosition] = useState(0)
-  const [selectedMentionIndex, setSelectedMentionIndex] = useState(0)
-  const [mentionedUserIds, setMentionedUserIds] = useState<string[]>([])
 
   const screenPosition = useMemo(() => {
     return flowToScreenPosition(position)
   }, [position.x, position.y, viewport.x, viewport.y, viewport.zoom, flowToScreenPosition])
 
-  const loadMentionableUsers = useCallback(async () => {
-    if (!appId) return
-    try {
-      const users = await fetchMentionableUsers(appId)
-      setMentionUsers(users)
-    }
- catch (error) {
-      console.error('Failed to load mentionable users:', error)
-    }
-  }, [appId])
-
-  useEffect(() => {
-    loadMentionableUsers()
-  }, [loadMentionableUsers])
-
   useEffect(() => {
     const handleGlobalKeyDown = (e: KeyboardEvent) => {
       if (e.key === 'Escape') {
@@ -67,142 +37,10 @@ export const CommentInput: FC<CommentInputProps> = memo(({ position, onSubmit, o
     }
   }, [onCancel])
 
-  const filteredMentionUsers = useMemo(() => {
-    if (!mentionQuery) return mentionUsers
-    return mentionUsers.filter(user =>
-      user.name.toLowerCase().includes(mentionQuery.toLowerCase())
-      || user.email.toLowerCase().includes(mentionQuery.toLowerCase()),
-    )
-  }, [mentionUsers, mentionQuery])
-
-  const dropdownPosition = useMemo(() => {
-    if (!showMentionDropdown || !textareaRef.current)
-      return { x: 0, y: 0 }
-
-    const textareaRect = textareaRef.current.getBoundingClientRect()
-    return {
-      x: textareaRect.left,
-      y: textareaRect.bottom + 4,
-    }
-  }, [showMentionDropdown])
-
-  const handleContentChange = useCallback((value: string) => {
-    setContent(value)
-
-    // Delay getting cursor position to ensure the textarea has updated
-    setTimeout(() => {
-      const cursorPosition = textareaRef.current?.selectionStart || 0
-      const textBeforeCursor = value.slice(0, cursorPosition)
-      const mentionMatch = textBeforeCursor.match(/@(\w*)$/)
-
-      if (mentionMatch) {
-        setMentionQuery(mentionMatch[1])
-        setMentionPosition(cursorPosition - mentionMatch[0].length)
-        setShowMentionDropdown(true)
-        setSelectedMentionIndex(0)
-      }
- else {
-        setShowMentionDropdown(false)
-      }
-    }, 0)
-  }, [])
-
-  const handleMentionButtonClick = useCallback((e: React.MouseEvent) => {
-    e.preventDefault()
-    e.stopPropagation()
-    console.log('Mention button clicked!')
-
-    const textarea = textareaRef.current
-    if (!textarea) return
-
-    const cursorPosition = textarea.selectionStart || 0
-    const newContent = `${content.slice(0, cursorPosition)}@${content.slice(cursorPosition)}`
-
-    setContent(newContent)
-
-    setTimeout(() => {
-      const newCursorPos = cursorPosition + 1
-      textarea.setSelectionRange(newCursorPos, newCursorPos)
-      textarea.focus()
-
-      setMentionQuery('')
-      setMentionPosition(cursorPosition)
-      setShowMentionDropdown(true)
-      setSelectedMentionIndex(0)
-    }, 0)
-  }, [content])
-
-  const insertMention = useCallback((user: UserProfile) => {
-    const textarea = textareaRef.current
-    if (!textarea) return
-
-    const beforeMention = content.slice(0, mentionPosition)
-    const afterMention = content.slice(textarea.selectionStart || 0)
-    const newContent = `${beforeMention}@${user.name} ${afterMention}`
-
-    setContent(newContent)
-    setShowMentionDropdown(false)
-    setMentionedUserIds(prev => [...prev, user.id])
-
-    setTimeout(() => {
-      const newCursorPos = mentionPosition + user.name.length + 2 // @ + name + space
-      textarea.setSelectionRange(newCursorPos, newCursorPos)
-      textarea.focus()
-    }, 0)
-  }, [content, mentionPosition])
-
-  const handleSubmit = useCallback((e?: React.MouseEvent) => {
-    if (e) {
-      e.preventDefault()
-      e.stopPropagation()
-    }
-    console.log('Submit button clicked!')
-
-    try {
-      if (content.trim()) {
-        onSubmit(content.trim(), mentionedUserIds)
-        setContent('')
-        setMentionedUserIds([])
-      }
-    }
-    catch (error) {
-      console.error('Error in CommentInput handleSubmit:', error)
-    }
-  }, [content, mentionedUserIds, onSubmit])
-
-  const handleKeyDown = useCallback((e: React.KeyboardEvent) => {
-    if (showMentionDropdown) {
-      if (e.key === 'ArrowDown') {
-        e.preventDefault()
-        setSelectedMentionIndex(prev =>
-          prev < filteredMentionUsers.length - 1 ? prev + 1 : 0,
-        )
-      }
- else if (e.key === 'ArrowUp') {
-        e.preventDefault()
-        setSelectedMentionIndex(prev =>
-          prev > 0 ? prev - 1 : filteredMentionUsers.length - 1,
-        )
-      }
- else if (e.key === 'Enter') {
-        e.preventDefault()
-        if (filteredMentionUsers[selectedMentionIndex])
-          insertMention(filteredMentionUsers[selectedMentionIndex])
-
-        return
-      }
- else if (e.key === 'Escape') {
-        e.preventDefault()
-        setShowMentionDropdown(false)
-        return
-      }
-    }
-
-    if (e.key === 'Enter' && !e.shiftKey && !showMentionDropdown) {
-      e.preventDefault()
-      handleSubmit()
-    }
-  }, [showMentionDropdown, filteredMentionUsers, selectedMentionIndex, insertMention, handleSubmit])
+  const handleMentionSubmit = useCallback((content: string, mentionedUserIds: string[]) => {
+    onSubmit(content, mentionedUserIds)
+    setContent('')
+  }, [onSubmit])
 
   return (
     <div
@@ -236,84 +74,19 @@ export const CommentInput: FC<CommentInputProps> = memo(({ position, onSubmit, o
           )}
         >
           <div className='relative px-[9px] pt-[9px]'>
-            <div className='relative'>
-              <div className='relative flex w-full grow items-start'>
-                <Textarea
-                  ref={textareaRef}
-                  className={cn(
-                    'body-lg-regular relative z-10 w-full resize-none bg-transparent p-1 leading-6 caret-primary-500 outline-none',
-                  )}
-                  placeholder="Add a comment"
-                  autoFocus
-                  minRows={1}
-                  maxRows={4}
-                  value={content}
-                  onChange={(e) => {
-                    handleContentChange(e.target.value)
-                  }}
-                  onKeyDown={handleKeyDown}
-                />
-              </div>
-              <div className="absolute bottom-0 right-1 z-20 flex items-end gap-1">
-                <div
-                  className="z-20 flex h-8 w-8 cursor-pointer items-center justify-center rounded-lg bg-components-button-secondary-bg hover:bg-state-base-hover"
-                  onClick={handleMentionButtonClick}
-                >
-                  <svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" viewBox="0 0 16 16" fill="none">
-                    <path d="M13.3334 8.00004C13.3334 5.05452 10.9456 2.66671 8.00004 2.66671C5.05452 2.66671 2.66671 5.05452 2.66671 8.00004C2.66671 10.9456 5.05452 13.3334 8.00004 13.3334C9.09457 13.3334 10.1121 13.0036 10.9588 12.4381L11.6984 13.5476C10.6402 14.2546 9.36824 14.6667 8.00004 14.6667C4.31814 14.6667 1.33337 11.6819 1.33337 8.00004C1.33337 4.31814 4.31814 1.33337 8.00004 1.33337C11.6819 1.33337 14.6667 4.31814 14.6667 8.00004V9.00004C14.6667 10.2887 13.622 11.3334 12.3334 11.3334C11.5306 11.3334 10.8224 10.9279 10.4026 10.3106C9.79617 10.941 8.94391 11.3334 8.00004 11.3334C6.15909 11.3334 4.66671 9.84097 4.66671 8.00004C4.66671 6.15909 6.15909 4.66671 8.00004 4.66671C8.75057 4.66671 9.44317 4.91477 10.0004 5.33337H11.3334V9.00004C11.3334 9.55231 11.7811 10 12.3334 10C12.8856 10 13.3334 9.55231 13.3334 9.00004V8.00004ZM8.00004 6.00004C6.89544 6.00004 6.00004 6.89544 6.00004 8.00004C6.00004 9.10464 6.89544 10 8.00004 10C9.10464 10 10 9.10464 10 8.00004C10 6.89544 9.10464 6.00004 8.00004 6.00004Z" fill="#676F83"/>
-                  </svg>
-                </div>
-                <Button
-                  className='z-20 ml-2 w-8 px-0'
-                  variant='primary'
-                  disabled={!content.trim()}
-                  onClick={handleSubmit}
-                >
-                  <RiSendPlane2Fill className='h-4 w-4' />
-                </Button>
-              </div>
-            </div>
+            <MentionInput
+              value={content}
+              onChange={setContent}
+              onSubmit={handleMentionSubmit}
+              placeholder="Add a comment"
+              autoFocus
+              minRows={1}
+              maxRows={4}
+              className="relative"
+            />
           </div>
         </div>
       </div>
-
-      {showMentionDropdown && filteredMentionUsers.length > 0 && typeof document !== 'undefined' && createPortal(
-        <div
-          className="fixed z-[9999] max-h-40 w-64 overflow-y-auto rounded-lg border border-components-panel-border bg-white shadow-lg"
-          style={{
-            left: dropdownPosition.x,
-            top: dropdownPosition.y,
-          }}
-          data-mention-dropdown
-        >
-          {filteredMentionUsers.map((user, index) => (
-            <div
-              key={user.id}
-              className={cn(
-                'flex cursor-pointer items-center gap-2 p-2 hover:bg-state-base-hover',
-                index === selectedMentionIndex && 'bg-state-base-hover',
-              )}
-              onClick={() => insertMention(user)}
-            >
-              <Avatar
-                avatar={user.avatar_url || null}
-                name={user.name}
-                size={24}
-                className="shrink-0"
-              />
-              <div className="min-w-0 flex-1">
-                <div className="truncate text-sm font-medium text-text-primary">
-                  {user.name}
-                </div>
-                <div className="truncate text-xs text-text-tertiary">
-                  {user.email}
-                </div>
-              </div>
-            </div>
-          ))}
-        </div>,
-        document.body,
-      )}
     </div>
   )
 })
diff --git a/web/app/components/workflow/comment/mention-input.tsx b/web/app/components/workflow/comment/mention-input.tsx
new file mode 100644
index 0000000000..64a5ab63c4
--- /dev/null
+++ b/web/app/components/workflow/comment/mention-input.tsx
@@ -0,0 +1,297 @@
+'use client'
+
+import type { FC } from 'react'
+import { memo, useCallback, useEffect, useMemo, useRef, useState } from 'react'
+import { createPortal } from 'react-dom'
+import { useParams } from 'next/navigation'
+import { RiArrowUpLine, RiAtLine } from '@remixicon/react'
+import Textarea from 'react-textarea-autosize'
+import Button from '@/app/components/base/button'
+import Avatar from '@/app/components/base/avatar'
+import cn from '@/utils/classnames'
+import { type UserProfile, fetchMentionableUsers } from '@/service/workflow-comment'
+
+type MentionInputProps = {
+  value: string
+  onChange: (value: string) => void
+  onSubmit: (content: string, mentionedUserIds: string[]) => void
+  onKeyDown?: (e: React.KeyboardEvent) => void
+  placeholder?: string
+  disabled?: boolean
+  loading?: boolean
+  className?: string
+  minRows?: number
+  maxRows?: number
+  showSubmitButton?: boolean
+  showMentionButton?: boolean
+  submitButtonIcon?: React.ReactNode
+  autoFocus?: boolean
+}
+
+export const MentionInput: FC<MentionInputProps> = memo(({
+  value,
+  onChange,
+  onSubmit,
+  onKeyDown,
+  placeholder = 'Add a comment',
+  disabled = false,
+  loading = false,
+  className,
+  showSubmitButton = true,
+  showMentionButton = true,
+  autoFocus = false,
+}) => {
+  const params = useParams()
+  const appId = params.appId as string
+  const textareaRef = useRef<HTMLTextAreaElement>(null)
+
+  const [mentionUsers, setMentionUsers] = useState<UserProfile[]>([])
+  const [showMentionDropdown, setShowMentionDropdown] = useState(false)
+  const [mentionQuery, setMentionQuery] = useState('')
+  const [mentionPosition, setMentionPosition] = useState(0)
+  const [selectedMentionIndex, setSelectedMentionIndex] = useState(0)
+  const [mentionedUserIds, setMentionedUserIds] = useState<string[]>([])
+
+  const loadMentionableUsers = useCallback(async () => {
+    if (!appId) return
+    try {
+      const users = await fetchMentionableUsers(appId)
+      setMentionUsers(users)
+    }
+ catch (error) {
+      console.error('Failed to load mentionable users:', error)
+    }
+  }, [appId])
+
+  useEffect(() => {
+    loadMentionableUsers()
+  }, [loadMentionableUsers])
+
+  const filteredMentionUsers = useMemo(() => {
+    if (!mentionQuery) return mentionUsers
+    return mentionUsers.filter(user =>
+      user.name.toLowerCase().includes(mentionQuery.toLowerCase())
+      || user.email.toLowerCase().includes(mentionQuery.toLowerCase()),
+    )
+  }, [mentionUsers, mentionQuery])
+
+  const dropdownPosition = useMemo(() => {
+    if (!showMentionDropdown || !textareaRef.current)
+      return { x: 0, y: 0 }
+
+    const textareaRect = textareaRef.current.getBoundingClientRect()
+    return {
+      x: textareaRect.left,
+      y: textareaRect.bottom + 4,
+    }
+  }, [showMentionDropdown])
+
+  const handleContentChange = useCallback((newValue: string) => {
+    onChange(newValue)
+
+    setTimeout(() => {
+      const cursorPosition = textareaRef.current?.selectionStart || 0
+      const textBeforeCursor = newValue.slice(0, cursorPosition)
+      const mentionMatch = textBeforeCursor.match(/@(\w*)$/)
+
+      if (mentionMatch) {
+        setMentionQuery(mentionMatch[1])
+        setMentionPosition(cursorPosition - mentionMatch[0].length)
+        setShowMentionDropdown(true)
+        setSelectedMentionIndex(0)
+      }
+ else {
+        setShowMentionDropdown(false)
+      }
+    }, 0)
+  }, [onChange])
+
+  const handleMentionButtonClick = useCallback((e: React.MouseEvent) => {
+    e.preventDefault()
+    e.stopPropagation()
+
+    const textarea = textareaRef.current
+    if (!textarea) return
+
+    const cursorPosition = textarea.selectionStart || 0
+    const newContent = `${value.slice(0, cursorPosition)}@${value.slice(cursorPosition)}`
+
+    onChange(newContent)
+
+    setTimeout(() => {
+      const newCursorPos = cursorPosition + 1
+      textarea.setSelectionRange(newCursorPos, newCursorPos)
+      textarea.focus()
+
+      setMentionQuery('')
+      setMentionPosition(cursorPosition)
+      setShowMentionDropdown(true)
+      setSelectedMentionIndex(0)
+    }, 0)
+  }, [value, onChange])
+
+  const insertMention = useCallback((user: UserProfile) => {
+    const textarea = textareaRef.current
+    if (!textarea) return
+
+    const beforeMention = value.slice(0, mentionPosition)
+    const afterMention = value.slice(textarea.selectionStart || 0)
+    const newContent = `${beforeMention}@${user.name} ${afterMention}`
+
+    onChange(newContent)
+    setShowMentionDropdown(false)
+    setMentionedUserIds(prev => [...prev, user.id])
+
+    setTimeout(() => {
+      const newCursorPos = mentionPosition + user.name.length + 2 // @ + name + space
+      textarea.setSelectionRange(newCursorPos, newCursorPos)
+      textarea.focus()
+    }, 0)
+  }, [value, mentionPosition, onChange])
+
+  const handleSubmit = useCallback((e?: React.MouseEvent) => {
+    if (e) {
+      e.preventDefault()
+      e.stopPropagation()
+    }
+
+    if (value.trim()) {
+      onSubmit(value.trim(), mentionedUserIds)
+      setMentionedUserIds([])
+      setShowMentionDropdown(false)
+    }
+  }, [value, mentionedUserIds, onSubmit])
+
+  const handleKeyDown = useCallback((e: React.KeyboardEvent) => {
+    if (showMentionDropdown) {
+      if (e.key === 'ArrowDown') {
+        e.preventDefault()
+        setSelectedMentionIndex(prev =>
+          prev < filteredMentionUsers.length - 1 ? prev + 1 : 0,
+        )
+      }
+ else if (e.key === 'ArrowUp') {
+        e.preventDefault()
+        setSelectedMentionIndex(prev =>
+          prev > 0 ? prev - 1 : filteredMentionUsers.length - 1,
+        )
+      }
+ else if (e.key === 'Enter') {
+        e.preventDefault()
+        if (filteredMentionUsers[selectedMentionIndex])
+          insertMention(filteredMentionUsers[selectedMentionIndex])
+
+        return
+      }
+ else if (e.key === 'Escape') {
+        e.preventDefault()
+        setShowMentionDropdown(false)
+        return
+      }
+    }
+
+    if (e.key === 'Enter' && !e.shiftKey && !showMentionDropdown) {
+      e.preventDefault()
+      handleSubmit()
+    }
+
+    onKeyDown?.(e)
+  }, [showMentionDropdown, filteredMentionUsers, selectedMentionIndex, insertMention, handleSubmit, onKeyDown])
+
+  const resetMentionState = useCallback(() => {
+    setMentionedUserIds([])
+    setShowMentionDropdown(false)
+    setMentionQuery('')
+    setMentionPosition(0)
+    setSelectedMentionIndex(0)
+  }, [])
+
+  useEffect(() => {
+    if (!value)
+      resetMentionState()
+  }, [value, resetMentionState])
+
+  return (
+    <>
+      <div className={cn('relative flex items-center', className)}>
+        <Textarea
+          ref={textareaRef}
+          className={cn(
+            'body-lg-regular w-full resize-none bg-transparent p-1 leading-6 text-text-primary caret-primary-500 outline-none',
+          )}
+          placeholder={placeholder}
+          autoFocus={autoFocus}
+          minRows={1}
+          maxRows={4}
+          value={value}
+          disabled={disabled || loading}
+          onChange={e => handleContentChange(e.target.value)}
+          onKeyDown={handleKeyDown}
+        />
+
+        {(showMentionButton || showSubmitButton) && (
+          <div className="absolute bottom-0 right-1 z-20 flex items-end gap-1">
+            {showMentionButton && (
+              <div
+                className="z-20 flex h-8 w-8 cursor-pointer items-center justify-center rounded-lg bg-components-button-secondary-bg hover:bg-state-base-hover"
+                onClick={handleMentionButtonClick}
+              >
+                <RiAtLine className="h-4 w-4" />
+              </div>
+            )}
+            {showSubmitButton && (
+              <Button
+                className='z-20 ml-2 w-8 px-0'
+                variant='primary'
+                disabled={!value.trim() || disabled || loading}
+                onClick={handleSubmit}
+              >
+                <RiArrowUpLine className='h-4 w-4' />
+              </Button>
+            )}
+          </div>
+        )}
+      </div>
+
+      {showMentionDropdown && filteredMentionUsers.length > 0 && typeof document !== 'undefined' && createPortal(
+        <div
+          className="fixed z-[9999] max-h-40 w-64 overflow-y-auto rounded-lg border border-components-panel-border bg-white shadow-lg"
+          style={{
+            left: dropdownPosition.x,
+            top: dropdownPosition.y,
+          }}
+          data-mention-dropdown
+        >
+          {filteredMentionUsers.map((user, index) => (
+            <div
+              key={user.id}
+              className={cn(
+                'flex cursor-pointer items-center gap-2 p-2 hover:bg-state-base-hover',
+                index === selectedMentionIndex && 'bg-state-base-hover',
+              )}
+              onClick={() => insertMention(user)}
+            >
+              <Avatar
+                avatar={user.avatar_url || null}
+                name={user.name}
+                size={24}
+                className="shrink-0"
+              />
+              <div className="min-w-0 flex-1">
+                <div className="truncate text-sm font-medium text-text-primary">
+                  {user.name}
+                </div>
+                <div className="truncate text-xs text-text-tertiary">
+                  {user.email}
+                </div>
+              </div>
+            </div>
+          ))}
+        </div>,
+        document.body,
+      )}
+    </>
+  )
+})
+
+MentionInput.displayName = 'MentionInput'
diff --git a/web/app/components/workflow/comment/thread.tsx b/web/app/components/workflow/comment/thread.tsx
index f646c3431b..ec098deb69 100644
--- a/web/app/components/workflow/comment/thread.tsx
+++ b/web/app/components/workflow/comment/thread.tsx
@@ -1,21 +1,16 @@
 'use client'
 
-import { useParams } from 'next/navigation'
-
 import type { FC } from 'react'
-import { memo, useCallback, useEffect, useMemo, useRef, useState } from 'react'
-import { createPortal } from 'react-dom'
+import { memo, useCallback, useEffect, useMemo, useState } from 'react'
 import { useReactFlow, useViewport } from 'reactflow'
-import { RiArrowDownSLine, RiArrowUpLine, RiArrowUpSLine, RiAtLine, RiCheckboxCircleFill, RiCheckboxCircleLine, RiCloseLine, RiDeleteBinLine } from '@remixicon/react'
-import Textarea from 'react-textarea-autosize'
+import { RiArrowDownSLine, RiArrowUpSLine, RiCheckboxCircleFill, RiCheckboxCircleLine, RiCloseLine, RiDeleteBinLine } from '@remixicon/react'
 import Avatar from '@/app/components/base/avatar'
-import Button from '@/app/components/base/button'
 import Divider from '@/app/components/base/divider'
 import cn from '@/utils/classnames'
 import { useFormatTimeFromNow } from '@/app/components/workflow/hooks'
-import type { UserProfile, WorkflowCommentDetail, WorkflowCommentDetailReply } from '@/service/workflow-comment'
-import { fetchMentionableUsers } from '@/service/workflow-comment'
+import type { WorkflowCommentDetail, WorkflowCommentDetailReply } from '@/service/workflow-comment'
 import { useAppContext } from '@/context/app-context'
+import { MentionInput } from './mention-input'
 
 type CommentThreadProps = {
   comment: WorkflowCommentDetail
@@ -83,170 +78,26 @@ export const CommentThread: FC<CommentThreadProps> = memo(({
   canGoNext,
   onReply,
 }) => {
-  const params = useParams()
-  const appId = params?.appId as string | undefined
   const { flowToScreenPosition } = useReactFlow()
   const viewport = useViewport()
   const { userProfile } = useAppContext()
   const [replyContent, setReplyContent] = useState('')
-  const [mentionUsers, setMentionUsers] = useState<UserProfile[]>([])
-  const [mentionLoading, setMentionLoading] = useState(false)
-  const [mentionLoaded, setMentionLoaded] = useState(false)
-  const [showMentionDropdown, setShowMentionDropdown] = useState(false)
-  const [mentionQuery, setMentionQuery] = useState('')
-  const [mentionPosition, setMentionPosition] = useState(0)
-  const [selectedMentionIndex, setSelectedMentionIndex] = useState(0)
-  const [mentionedUserIds, setMentionedUserIds] = useState<string[]>([])
-  const textareaRef = useRef<HTMLTextAreaElement>(null)
-
-  const loadMentionUsers = useCallback(async () => {
-    if (!onReply || !appId) {
-      setMentionUsers([])
-      setMentionLoaded(false)
-      return
-    }
-    setMentionLoading(true)
-    try {
-      const users = await fetchMentionableUsers(appId)
-      setMentionUsers(users)
-      setMentionLoaded(true)
-    }
-    catch (error) {
-      console.error('Failed to load mention users', error)
-    }
-    finally {
-      setMentionLoading(false)
-    }
-  }, [appId, onReply])
-
-  useEffect(() => {
-    loadMentionUsers()
-  }, [loadMentionUsers])
 
   useEffect(() => {
     setReplyContent('')
-    setMentionedUserIds([])
-    setShowMentionDropdown(false)
   }, [comment.id])
 
-  const handleReplySubmit = useCallback(async () => {
-    const trimmed = replyContent.trim()
-    if (!onReply || !trimmed || loading)
-      return
+  const handleReplySubmit = useCallback(async (content: string, mentionedUserIds: string[]) => {
+    if (!onReply || loading) return
+
     try {
-      await onReply(trimmed, mentionedUserIds)
+      await onReply(content, mentionedUserIds)
       setReplyContent('')
-      setMentionedUserIds([])
-      setShowMentionDropdown(false)
     }
-    catch (error) {
+ catch (error) {
       console.error('Failed to send reply', error)
     }
-  }, [replyContent, onReply, loading, mentionedUserIds])
-
-  const filteredMentionUsers = useMemo(() => {
-    if (!mentionQuery) return mentionUsers
-    return mentionUsers.filter(user =>
-      user.name.toLowerCase().includes(mentionQuery.toLowerCase())
-      || user.email?.toLowerCase().includes(mentionQuery.toLowerCase()),
-    )
-  }, [mentionUsers, mentionQuery])
-
-  const dropdownPosition = useMemo(() => {
-    if (!showMentionDropdown || !textareaRef.current)
-      return { x: 0, y: 0 }
-    const rect = textareaRef.current.getBoundingClientRect()
-    return { x: rect.left, y: rect.bottom + 4 }
-  }, [showMentionDropdown])
-
-  const handleContentChange = useCallback((value: string) => {
-    setReplyContent(value)
-    setTimeout(() => {
-      const cursorPosition = textareaRef.current?.selectionStart || 0
-      const textBeforeCursor = value.slice(0, cursorPosition)
-      const mentionMatch = textBeforeCursor.match(/@(\w*)$/)
-      if (mentionMatch) {
-        setMentionQuery(mentionMatch[1])
-        setMentionPosition(cursorPosition - mentionMatch[0].length)
-        setShowMentionDropdown(true)
-        setSelectedMentionIndex(0)
-      }
-      else {
-        setShowMentionDropdown(false)
-      }
-    }, 0)
-  }, [])
-
-  const handleMentionButtonClick = useCallback(async (e: React.MouseEvent) => {
-    e.preventDefault()
-    e.stopPropagation()
-    if (!onReply || loading) return
-    if (!mentionLoaded && !mentionLoading)
-      await loadMentionUsers()
-    if (!textareaRef.current) return
-    const cursorPosition = textareaRef.current.selectionStart || 0
-    const newContent = `${replyContent.slice(0, cursorPosition)}@${replyContent.slice(cursorPosition)}`
-    setReplyContent(newContent)
-    setTimeout(() => {
-      const textarea = textareaRef.current
-      if (!textarea) return
-      const newCursorPos = cursorPosition + 1
-      textarea.setSelectionRange(newCursorPos, newCursorPos)
-      textarea.focus()
-      setMentionQuery('')
-      setMentionPosition(cursorPosition)
-      setShowMentionDropdown(true)
-      setSelectedMentionIndex(0)
-    }, 0)
-  }, [loadMentionUsers, mentionLoaded, mentionLoading, replyContent])
-
-  const insertMention = useCallback((user: UserProfile) => {
-    const textarea = textareaRef.current
-    if (!textarea) return
-    const beforeMention = replyContent.slice(0, mentionPosition)
-    const afterMention = replyContent.slice(textarea.selectionStart || 0)
-    const newContent = `${beforeMention}@${user.name} ${afterMention}`
-    setReplyContent(newContent)
-    setShowMentionDropdown(false)
-    setMentionedUserIds(prev => prev.includes(user.id) ? prev : [...prev, user.id])
-    setTimeout(() => {
-      const newCursorPos = mentionPosition + user.name.length + 2
-      textarea.setSelectionRange(newCursorPos, newCursorPos)
-      textarea.focus()
-    }, 0)
-  }, [mentionPosition, replyContent])
-
-  const handleReplyKeyDown = useCallback((e: React.KeyboardEvent<HTMLTextAreaElement>) => {
-    if (showMentionDropdown) {
-      if (e.key === 'ArrowDown') {
-        e.preventDefault()
-        setSelectedMentionIndex(prev => prev < filteredMentionUsers.length - 1 ? prev + 1 : 0)
-        return
-      }
-      if (e.key === 'ArrowUp') {
-        e.preventDefault()
-        setSelectedMentionIndex(prev => prev > 0 ? prev - 1 : filteredMentionUsers.length - 1)
-        return
-      }
-      if (e.key === 'Enter') {
-        e.preventDefault()
-        const targetUser = filteredMentionUsers[selectedMentionIndex]
-        if (targetUser)
-          insertMention(targetUser)
-        return
-      }
-      if (e.key === 'Escape') {
-        e.preventDefault()
-        setShowMentionDropdown(false)
-        return
-      }
-    }
-    if (!onReply) return
-    if (e.key === 'Enter' && !e.shiftKey) {
-      e.preventDefault()
-      handleReplySubmit()
-    }
-  }, [filteredMentionUsers, handleReplySubmit, insertMention, selectedMentionIndex, showMentionDropdown])
+  }, [onReply, loading])
 
   const screenPosition = useMemo(() => {
     return flowToScreenPosition({
@@ -343,70 +194,20 @@ export const CommentThread: FC<CommentThreadProps> = memo(({
                 className='h-8 w-8'
               />
               <div className='flex-1 rounded-xl border border-components-chat-input-border bg-components-panel-bg-blur p-[2px] shadow-sm'>
-                <div className='flex items-center gap-2'>
-                  <Textarea
-                    ref={textareaRef}
-                    minRows={1}
-                    maxRows={1}
-                    value={replyContent}
-                    placeholder='Add a reply'
-                    onChange={e => handleContentChange(e.target.value)}
-                    onKeyDown={handleReplyKeyDown}
-                    className='system-sm-regular h-8 w-full resize-none bg-transparent pl-2 leading-8 text-text-primary caret-primary-500 outline-none'
-                  />
-                  <button
-                    type='button'
-                    disabled={loading || mentionLoading}
-                    className={cn('z-20 flex h-8 w-8 items-center justify-center rounded-lg bg-components-button-secondary-bg hover:bg-state-base-hover')}
-                    onClick={handleMentionButtonClick}
-                    aria-label='Mention user'
-                  >
-                    <RiAtLine className='h-4 w-4' />
-                  </button>
-                  <Button
-                    variant='primary'
-                    disabled={loading || !onReply || !replyContent.trim()}
-                    onClick={handleReplySubmit}
-                    className='z-20 h-8 w-8'
-                  >
-                    <RiArrowUpLine className='h-4 w-4' />
-                  </Button>
-                </div>
+                <MentionInput
+                  value={replyContent}
+                  onChange={setReplyContent}
+                  onSubmit={handleReplySubmit}
+                  placeholder='Reply'
+                  disabled={loading}
+                  loading={loading}
+                  className='px-2'
+                />
               </div>
             </div>
           </div>
         )}
       </div>
-      {showMentionDropdown && filteredMentionUsers.length > 0 && typeof document !== 'undefined' && createPortal(
-        <div
-          className='fixed z-[9999] max-h-40 w-56 overflow-y-auto rounded-lg border border-components-panel-border bg-white shadow-lg'
-          style={{ left: dropdownPosition.x, top: dropdownPosition.y }}
-          data-mention-dropdown
-        >
-          {filteredMentionUsers.map((user, index) => (
-            <div
-              key={user.id}
-              className={cn(
-                'flex cursor-pointer items-center gap-2 p-2 hover:bg-state-base-hover',
-                index === selectedMentionIndex && 'bg-state-base-hover',
-              )}
-              onClick={() => insertMention(user)}
-            >
-              <Avatar
-                avatar={user.avatar_url || null}
-                name={user.name}
-                size={24}
-                className='shrink-0'
-              />
-              <div className='min-w-0 flex-1'>
-                <div className='truncate text-sm font-medium text-text-primary'>{user.name}</div>
-                <div className='truncate text-xs text-text-tertiary'>{user.email}</div>
-              </div>
-            </div>
-          ))}
-        </div>,
-        document.body,
-      )}
     </div>
   )
 })