diff --git a/web/app/components/workflow/comment/index.tsx b/web/app/components/workflow/comment/index.tsx
index 558c15089c..148d5094f8 100644
--- a/web/app/components/workflow/comment/index.tsx
+++ b/web/app/components/workflow/comment/index.tsx
@@ -1,3 +1,4 @@
 export { CommentCursor } from './cursor'
 export { CommentInput } from './input'
 export { CommentIcon } from './icon'
+export { CommentThread } from './thread'
diff --git a/web/app/components/workflow/comment/thread.tsx b/web/app/components/workflow/comment/thread.tsx
new file mode 100644
index 0000000000..f8d627b308
--- /dev/null
+++ b/web/app/components/workflow/comment/thread.tsx
@@ -0,0 +1,116 @@
+'use client'
+
+import type { FC } from 'react'
+import { memo, useMemo } from 'react'
+import { useReactFlow, useViewport } from 'reactflow'
+import { RiCloseLine } from '@remixicon/react'
+import Avatar from '@/app/components/base/avatar'
+import cn from '@/utils/classnames'
+import { useFormatTimeFromNow } from '@/app/components/workflow/hooks'
+import type { WorkflowCommentDetail, WorkflowCommentDetailReply } from '@/service/workflow-comment'
+
+type CommentThreadProps = {
+  comment: WorkflowCommentDetail
+  loading?: boolean
+  onClose: () => void
+}
+
+const ThreadMessage: FC<{
+  authorName: string
+  avatarUrl?: string | null
+  createdAt: number
+  content: string
+  isReply?: boolean
+}> = ({ authorName, avatarUrl, createdAt, content, isReply }) => {
+  const { formatTimeFromNow } = useFormatTimeFromNow()
+
+  return (
+    <div className={cn('flex gap-3', isReply && 'pl-9')}>
+      <div className='shrink-0'>
+        <Avatar
+          name={authorName}
+          avatar={avatarUrl || null}
+          size={32}
+          className='h-8 w-8'
+        />
+      </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'>
+          <span className='system-sm-medium text-text-primary'>{authorName}</span>
+          <span className='system-2xs-regular text-text-tertiary'>{formatTimeFromNow(createdAt * 1000)}</span>
+        </div>
+        <div className='system-sm-regular mt-1 whitespace-pre-wrap break-words text-text-secondary'>
+          {content}
+        </div>
+      </div>
+    </div>
+  )
+}
+
+const renderReply = (reply: WorkflowCommentDetailReply) => (
+  <ThreadMessage
+    key={reply.id}
+    authorName={reply.created_by_account?.name || 'User'}
+    avatarUrl={reply.created_by_account?.avatar_url || null}
+    createdAt={reply.created_at}
+    content={reply.content}
+    isReply
+  />
+)
+
+export const CommentThread: FC<CommentThreadProps> = memo(({ comment, loading = false, onClose }) => {
+  const { flowToScreenPosition } = useReactFlow()
+  const viewport = useViewport()
+
+  const screenPosition = useMemo(() => {
+    return flowToScreenPosition({
+      x: comment.position_x,
+      y: comment.position_y,
+    })
+  }, [comment.position_x, comment.position_y, viewport.x, viewport.y, viewport.zoom, flowToScreenPosition])
+
+  return (
+    <div
+      className='absolute z-50 w-[360px] max-w-[360px]'
+      style={{
+        left: screenPosition.x,
+        top: screenPosition.y,
+        transform: 'translate(-50%, -100%) translateY(-24px)',
+      }}
+    >
+      <div className='relative rounded-2xl border border-components-panel-border bg-components-panel-bg shadow-xl'>
+        <div className='flex items-center justify-between rounded-t-2xl px-4 py-3'>
+          <div className='system-2xs-semibold uppercase tracking-[0.08em] text-text-tertiary'>Comment</div>
+          <button
+            type='button'
+            className='flex h-6 w-6 items-center justify-center rounded-full text-text-tertiary hover:bg-state-base-hover hover:text-text-secondary'
+            onClick={onClose}
+            aria-label='Close comment'
+          >
+            <RiCloseLine className='h-4 w-4' />
+          </button>
+        </div>
+        <div className='relative px-4 pb-4'>
+          <ThreadMessage
+            authorName={comment.created_by_account?.name || 'User'}
+            avatarUrl={comment.created_by_account?.avatar_url || null}
+            createdAt={comment.created_at}
+            content={comment.content}
+          />
+          {comment.replies?.length > 0 && (
+            <div className='mt-2 flex flex-col gap-2'>
+              {comment.replies.map(renderReply)}
+            </div>
+          )}
+        </div>
+        {loading && (
+          <div className='bg-components-panel-bg/70 absolute inset-0 flex items-center justify-center rounded-2xl text-sm text-text-tertiary'>
+            Loading…
+          </div>
+        )}
+      </div>
+    </div>
+  )
+})
+
+CommentThread.displayName = 'CommentThread'
diff --git a/web/app/components/workflow/hooks/use-workflow-comment.ts b/web/app/components/workflow/hooks/use-workflow-comment.ts
index 42eae29705..27180cb1ab 100644
--- a/web/app/components/workflow/hooks/use-workflow-comment.ts
+++ b/web/app/components/workflow/hooks/use-workflow-comment.ts
@@ -1,10 +1,10 @@
-import { useCallback, useEffect, useState } from 'react'
+import { useCallback, useEffect, useRef, useState } from 'react'
 import { useParams } from 'next/navigation'
 import { useReactFlow } from 'reactflow'
 import { useStore } from '../store'
 import { ControlMode } from '../types'
-import type { WorkflowCommentList } from '@/service/workflow-comment'
-import { createWorkflowComment, fetchWorkflowComments } from '@/service/workflow-comment'
+import type { WorkflowCommentDetail, WorkflowCommentList } from '@/service/workflow-comment'
+import { createWorkflowComment, fetchWorkflowComment, fetchWorkflowComments } from '@/service/workflow-comment'
 
 export const useWorkflowComment = () => {
   const params = useParams()
@@ -14,8 +14,17 @@ export const useWorkflowComment = () => {
   const setControlMode = useStore(s => s.setControlMode)
   const pendingComment = useStore(s => s.pendingComment)
   const setPendingComment = useStore(s => s.setPendingComment)
+  const setActiveCommentId = useStore(s => s.setActiveCommentId)
+  const activeCommentId = useStore(s => s.activeCommentId)
   const [comments, setComments] = useState<WorkflowCommentList[]>([])
   const [loading, setLoading] = useState(false)
+  const [activeComment, setActiveComment] = useState<WorkflowCommentDetail | null>(null)
+  const [activeCommentLoading, setActiveCommentLoading] = useState(false)
+  const commentDetailCacheRef = useRef<Record<string, WorkflowCommentDetail>>({})
+  const activeCommentIdRef = useRef<string | null>(null)
+  useEffect(() => {
+    activeCommentIdRef.current = activeCommentId ?? null
+  }, [activeCommentId])
 
   const loadComments = useCallback(async () => {
     if (!appId) return
@@ -72,17 +81,50 @@ export const useWorkflowComment = () => {
     setControlMode(ControlMode.Pointer)
   }, [setControlMode, setPendingComment])
 
-  const handleCommentIconClick = useCallback((comment: WorkflowCommentList) => {
+  const handleCommentIconClick = useCallback(async (comment: WorkflowCommentList) => {
+    setPendingComment(null)
+
+    activeCommentIdRef.current = comment.id
+    setControlMode(ControlMode.Comment)
+    setActiveCommentId(comment.id)
+
+    const cachedDetail = commentDetailCacheRef.current[comment.id]
+    setActiveComment(cachedDetail || comment)
+
+    reactflow.setCenter(comment.position_x, comment.position_y, { zoom: 1, duration: 600 })
+
+    if (!appId) return
+
+    if (!cachedDetail)
+      setActiveCommentLoading(true)
+
     try {
-      const store = useStore.getState()
-      store.setControlMode(ControlMode.Comment)
-      store.setActiveCommentId(comment.id)
-      reactflow.setCenter(comment.position_x, comment.position_y, { zoom: 1, duration: 600 })
+      const detailResponse = await fetchWorkflowComment(appId, comment.id)
+      const detail = (detailResponse as any)?.data ?? detailResponse
+
+      commentDetailCacheRef.current = {
+        ...commentDetailCacheRef.current,
+        [comment.id]: detail,
+      }
+
+      if (activeCommentIdRef.current === comment.id)
+        setActiveComment(detail)
     }
     catch (e) {
-      console.error('Failed to open comments panel:', e)
+      console.warn('Failed to load workflow comment detail', e)
     }
-  }, [reactflow])
+    finally {
+      setActiveCommentLoading(false)
+    }
+  }, [appId, reactflow, setPendingComment])
+
+  const handleActiveCommentClose = useCallback(() => {
+    setActiveComment(null)
+    setActiveCommentLoading(false)
+    setActiveCommentId(null)
+    setControlMode(ControlMode.Pointer)
+    activeCommentIdRef.current = null
+  }, [setActiveCommentId, setControlMode])
 
   const handleCreateComment = useCallback((mousePosition: { pageX: number; pageY: number }) => {
     if (controlMode === ControlMode.Comment) {
@@ -101,9 +143,12 @@ export const useWorkflowComment = () => {
     comments,
     loading,
     pendingComment,
+    activeComment,
+    activeCommentLoading,
     handleCommentSubmit,
     handleCommentCancel,
     handleCommentIconClick,
+    handleActiveCommentClose,
     handleCreateComment,
     loadComments,
   }
diff --git a/web/app/components/workflow/index.tsx b/web/app/components/workflow/index.tsx
index 8e65d1a804..0f21a6290b 100644
--- a/web/app/components/workflow/index.tsx
+++ b/web/app/components/workflow/index.tsx
@@ -69,7 +69,7 @@ import PanelContextmenu from './panel-contextmenu'
 import NodeContextmenu from './node-contextmenu'
 import SyncingDataModal from './syncing-data-modal'
 import LimitTips from './limit-tips'
-import { CommentCursor, CommentIcon, CommentInput } from './comment'
+import { CommentCursor, CommentIcon, CommentInput, CommentThread } from './comment'
 import { useWorkflowComment } from './hooks/use-workflow-comment'
 import {
   useStore,
@@ -164,9 +164,12 @@ export const Workflow: FC<WorkflowProps> = memo(({
   const {
     comments,
     pendingComment,
+    activeComment,
+    activeCommentLoading,
     handleCommentSubmit,
     handleCommentCancel,
     handleCommentIconClick,
+    handleActiveCommentClose,
   } = useWorkflowComment()
   const mousePosition = useStore(s => s.mousePosition)
 
@@ -351,13 +354,28 @@ export const Workflow: FC<WorkflowProps> = memo(({
           onCancel={handleCommentCancel}
         />
       )}
-      {comments.map(comment => (
-        <CommentIcon
-          key={comment.id}
-          comment={comment}
-          onClick={() => handleCommentIconClick(comment)}
-        />
-      ))}
+      {comments.map((comment) => {
+        const isActive = activeComment?.id === comment.id
+
+        if (isActive && activeComment) {
+          return (
+            <CommentThread
+              key={comment.id}
+              comment={activeComment}
+              loading={activeCommentLoading}
+              onClose={handleActiveCommentClose}
+            />
+          )
+        }
+
+        return (
+          <CommentIcon
+            key={comment.id}
+            comment={comment}
+            onClick={() => handleCommentIconClick(comment)}
+          />
+        )
+      })}
       {children}
       <ReactFlow
         nodeTypes={nodeTypes}
diff --git a/web/service/workflow-comment.ts b/web/service/workflow-comment.ts
index e9a34a4bf3..b065d0b9c7 100644
--- a/web/service/workflow-comment.ts
+++ b/web/service/workflow-comment.ts
@@ -26,6 +26,20 @@ export type WorkflowCommentList = {
   participants: UserProfile[]
 }
 
+export type WorkflowCommentDetailMention = {
+  mentioned_user_id: string
+  mentioned_user_account?: UserProfile | null
+  reply_id: string | null
+}
+
+export type WorkflowCommentDetailReply = {
+  id: string
+  content: string
+  created_by: string
+  created_by_account?: UserProfile | null
+  created_at: number
+}
+
 export type WorkflowCommentDetail = {
   id: string
   position_x: number
@@ -33,14 +47,14 @@ export type WorkflowCommentDetail = {
   content: string
   created_by: string
   created_by_account: UserProfile
-  created_at: string
-  updated_at: string
+  created_at: number
+  updated_at: number
   resolved: boolean
   resolved_by?: string
   resolved_by_account?: UserProfile
-  resolved_at?: string
-  replies: []
-  mentions: []
+  resolved_at?: number
+  replies: WorkflowCommentDetailReply[]
+  mentions: WorkflowCommentDetailMention[]
 }
 
 export type WorkflowCommentCreateRes = {