feat: send email when user mentioned in comment

api/libs/email_i18n.py

@@ -37,6 +37,7 @@ class EmailType(StrEnum):
     ENTERPRISE_CUSTOM = auto()
     QUEUE_MONITOR_ALERT = auto()
     DOCUMENT_CLEAN_NOTIFY = auto()
+    WORKFLOW_COMMENT_MENTION = auto()
     EMAIL_REGISTER = auto()
     EMAIL_REGISTER_WHEN_ACCOUNT_EXIST = auto()
     RESET_PASSWORD_WHEN_ACCOUNT_NOT_EXIST_NO_REGISTER = auto()
@@ -453,6 +454,18 @@ def create_default_email_config() -> EmailI18nConfig:
                 branded_template_path="clean_document_job_mail_template_zh-CN.html",
             ),
         },
+        EmailType.WORKFLOW_COMMENT_MENTION: {
+            EmailLanguage.EN_US: EmailTemplate(
+                subject="You were mentioned in a workflow comment",
+                template_path="workflow_comment_mention_template_en-US.html",
+                branded_template_path="without-brand/workflow_comment_mention_template_en-US.html",
+            ),
+            EmailLanguage.ZH_HANS: EmailTemplate(
+                subject="你在工作流评论中被提及",
+                template_path="workflow_comment_mention_template_zh-CN.html",
+                branded_template_path="without-brand/workflow_comment_mention_template_zh-CN.html",
+            ),
+        },
         EmailType.TRIGGER_EVENTS_LIMIT_SANDBOX: {
             EmailLanguage.EN_US: EmailTemplate(
                 subject="You’ve reached your Sandbox Trigger Events limit",

api/services/workflow_comment_service.py

@@ -8,8 +8,9 @@ from werkzeug.exceptions import Forbidden, NotFound
 from extensions.ext_database import db
 from libs.datetime_utils import naive_utc_now
 from libs.helper import uuid_value
-from models import WorkflowComment, WorkflowCommentMention, WorkflowCommentReply
+from models import App, TenantAccountJoin, WorkflowComment, WorkflowCommentMention, WorkflowCommentReply
 from models.account import Account
+from tasks.mail_workflow_comment_task import send_workflow_comment_mention_email_task
 
 logger = logging.getLogger(__name__)
 
@@ -25,6 +26,94 @@ class WorkflowCommentService:
         if len(content) > 1000:
             raise ValueError("Comment content cannot exceed 1000 characters")
 
+    @staticmethod
+    def _filter_valid_mentioned_user_ids(mentioned_user_ids: Sequence[str]) -> list[str]:
+        """Return deduplicated UUID user IDs in the order provided."""
+        unique_user_ids: list[str] = []
+        seen: set[str] = set()
+        for user_id in mentioned_user_ids:
+            if not isinstance(user_id, str):
+                continue
+            if not uuid_value(user_id):
+                continue
+            if user_id in seen:
+                continue
+            seen.add(user_id)
+            unique_user_ids.append(user_id)
+        return unique_user_ids
+
+    @staticmethod
+    def _format_comment_excerpt(content: str, max_length: int = 200) -> str:
+        """Trim comment content for email display."""
+        trimmed = content.strip()
+        if len(trimmed) <= max_length:
+            return trimmed
+        if max_length <= 3:
+            return trimmed[:max_length]
+        return f"{trimmed[: max_length - 3].rstrip()}..."
+
+    @staticmethod
+    def _build_mention_email_payloads(
+        session: Session,
+        tenant_id: str,
+        app_id: str,
+        mentioner_id: str,
+        mentioned_user_ids: Sequence[str],
+        content: str,
+    ) -> list[dict[str, str]]:
+        """Prepare email payloads for mentioned users."""
+        if not mentioned_user_ids:
+            return []
+
+        candidate_user_ids = [user_id for user_id in mentioned_user_ids if user_id != mentioner_id]
+        if not candidate_user_ids:
+            return []
+
+        app_name_value = session.scalar(select(App.name).where(App.id == app_id, App.tenant_id == tenant_id))
+        app_name = app_name_value if isinstance(app_name_value, str) and app_name_value else "Dify app"
+        commenter_name_value = session.scalar(select(Account.name).where(Account.id == mentioner_id))
+        commenter_name = (
+            commenter_name_value
+            if isinstance(commenter_name_value, str) and commenter_name_value
+            else "Dify user"
+        )
+        comment_excerpt = WorkflowCommentService._format_comment_excerpt(content)
+
+        accounts = session.scalars(
+            select(Account)
+            .join(TenantAccountJoin, TenantAccountJoin.account_id == Account.id)
+            .where(TenantAccountJoin.tenant_id == tenant_id, Account.id.in_(candidate_user_ids))
+        ).all()
+
+        payloads: list[dict[str, str]] = []
+        for account in accounts:
+            email = account.email
+            if not isinstance(email, str) or not email:
+                continue
+            mentioned_name = account.name if isinstance(account.name, str) and account.name else email
+            language = (
+                account.interface_language
+                if isinstance(account.interface_language, str) and account.interface_language
+                else "en-US"
+            )
+            payloads.append(
+                {
+                    "language": language,
+                    "to": email,
+                    "mentioned_name": mentioned_name,
+                    "commenter_name": commenter_name,
+                    "app_name": app_name,
+                    "comment_content": comment_excerpt,
+                }
+            )
+        return payloads
+
+    @staticmethod
+    def _dispatch_mention_emails(payloads: Sequence[dict[str, str]]) -> None:
+        """Enqueue mention notification emails."""
+        for payload in payloads:
+            send_workflow_comment_mention_email_task.delay(**payload)
+
     @staticmethod
     def get_comments(tenant_id: str, app_id: str) -> Sequence[WorkflowComment]:
         """Get all comments for a workflow."""
@@ -112,7 +201,7 @@ class WorkflowCommentService:
         position_y: float,
         mentioned_user_ids: list[str] | None = None,
     ) -> dict:
-        """Create a new workflow comment."""
+        """Create a new workflow comment and send mention notification emails."""
         WorkflowCommentService._validate_content(content)
 
         with Session(db.engine) as session:
@@ -129,17 +218,26 @@ class WorkflowCommentService:
             session.flush()  # Get the comment ID for mentions
 
             # Create mentions if specified
-            mentioned_user_ids = mentioned_user_ids or []
+            mentioned_user_ids = WorkflowCommentService._filter_valid_mentioned_user_ids(mentioned_user_ids or [])
             for user_id in mentioned_user_ids:
-                if isinstance(user_id, str) and uuid_value(user_id):
-                    mention = WorkflowCommentMention(
-                        comment_id=comment.id,
-                        reply_id=None,  # This is a comment mention, not reply mention
-                        mentioned_user_id=user_id,
-                    )
-                    session.add(mention)
+                mention = WorkflowCommentMention(
+                    comment_id=comment.id,
+                    reply_id=None,  # This is a comment mention, not reply mention
+                    mentioned_user_id=user_id,
+                )
+                session.add(mention)
+
+            mention_email_payloads = WorkflowCommentService._build_mention_email_payloads(
+                session=session,
+                tenant_id=tenant_id,
+                app_id=app_id,
+                mentioner_id=created_by,
+                mentioned_user_ids=mentioned_user_ids,
+                content=content,
+            )
 
             session.commit()
+            WorkflowCommentService._dispatch_mention_emails(mention_email_payloads)
 
             # Return only what we need - id and created_at
             return {"id": comment.id, "created_at": comment.created_at}
@@ -155,7 +253,7 @@ class WorkflowCommentService:
         position_y: float | None = None,
         mentioned_user_ids: list[str] | None = None,
     ) -> dict:
-        """Update a workflow comment."""
+        """Update a workflow comment and notify newly mentioned users."""
         WorkflowCommentService._validate_content(content)
 
         with Session(db.engine, expire_on_commit=False) as session:
@@ -188,21 +286,34 @@ class WorkflowCommentService:
                     WorkflowCommentMention.reply_id.is_(None),  # Only comment mentions, not reply mentions
                 )
             ).all()
+            existing_mentioned_user_ids = {mention.mentioned_user_id for mention in existing_mentions}
             for mention in existing_mentions:
                 session.delete(mention)
 
             # Add new mentions
-            mentioned_user_ids = mentioned_user_ids or []
+            mentioned_user_ids = WorkflowCommentService._filter_valid_mentioned_user_ids(mentioned_user_ids or [])
+            new_mentioned_user_ids = [
+                user_id for user_id in mentioned_user_ids if user_id not in existing_mentioned_user_ids
+            ]
             for user_id_str in mentioned_user_ids:
-                if isinstance(user_id_str, str) and uuid_value(user_id_str):
-                    mention = WorkflowCommentMention(
-                        comment_id=comment.id,
-                        reply_id=None,  # This is a comment mention
-                        mentioned_user_id=user_id_str,
-                    )
-                    session.add(mention)
+                mention = WorkflowCommentMention(
+                    comment_id=comment.id,
+                    reply_id=None,  # This is a comment mention
+                    mentioned_user_id=user_id_str,
+                )
+                session.add(mention)
+
+            mention_email_payloads = WorkflowCommentService._build_mention_email_payloads(
+                session=session,
+                tenant_id=tenant_id,
+                app_id=app_id,
+                mentioner_id=user_id,
+                mentioned_user_ids=new_mentioned_user_ids,
+                content=content,
+            )
 
             session.commit()
+            WorkflowCommentService._dispatch_mention_emails(mention_email_payloads)
 
             return {"id": comment.id, "updated_at": comment.updated_at}
 
@@ -252,7 +363,7 @@ class WorkflowCommentService:
     def create_reply(
         comment_id: str, content: str, created_by: str, mentioned_user_ids: list[str] | None = None
     ) -> dict:
-        """Add a reply to a workflow comment."""
+        """Add a reply to a workflow comment and notify mentioned users."""
         WorkflowCommentService._validate_content(content)
 
         with Session(db.engine, expire_on_commit=False) as session:
@@ -267,22 +378,31 @@ class WorkflowCommentService:
             session.flush()  # Get the reply ID for mentions
 
             # Create mentions if specified
-            mentioned_user_ids = mentioned_user_ids or []
+            mentioned_user_ids = WorkflowCommentService._filter_valid_mentioned_user_ids(mentioned_user_ids or [])
             for user_id in mentioned_user_ids:
-                if isinstance(user_id, str) and uuid_value(user_id):
-                    # Create mention linking to specific reply
-                    mention = WorkflowCommentMention(
-                        comment_id=comment_id, reply_id=reply.id, mentioned_user_id=user_id
-                    )
-                    session.add(mention)
+                # Create mention linking to specific reply
+                mention = WorkflowCommentMention(
+                    comment_id=comment_id, reply_id=reply.id, mentioned_user_id=user_id
+                )
+                session.add(mention)
+
+            mention_email_payloads = WorkflowCommentService._build_mention_email_payloads(
+                session=session,
+                tenant_id=comment.tenant_id,
+                app_id=comment.app_id,
+                mentioner_id=created_by,
+                mentioned_user_ids=mentioned_user_ids,
+                content=content,
+            )
 
             session.commit()
+            WorkflowCommentService._dispatch_mention_emails(mention_email_payloads)
 
             return {"id": reply.id, "created_at": reply.created_at}
 
     @staticmethod
     def update_reply(reply_id: str, user_id: str, content: str, mentioned_user_ids: list[str] | None = None) -> dict:
-        """Update a comment reply."""
+        """Update a comment reply and notify newly mentioned users."""
         WorkflowCommentService._validate_content(content)
 
         with Session(db.engine, expire_on_commit=False) as session:
@@ -300,20 +420,36 @@ class WorkflowCommentService:
             existing_mentions = session.scalars(
                 select(WorkflowCommentMention).where(WorkflowCommentMention.reply_id == reply.id)
             ).all()
+            existing_mentioned_user_ids = {mention.mentioned_user_id for mention in existing_mentions}
             for mention in existing_mentions:
                 session.delete(mention)
 
             # Add mentions
-            mentioned_user_ids = mentioned_user_ids or []
+            mentioned_user_ids = WorkflowCommentService._filter_valid_mentioned_user_ids(mentioned_user_ids or [])
+            new_mentioned_user_ids = [
+                user_id for user_id in mentioned_user_ids if user_id not in existing_mentioned_user_ids
+            ]
             for user_id_str in mentioned_user_ids:
-                if isinstance(user_id_str, str) and uuid_value(user_id_str):
-                    mention = WorkflowCommentMention(
-                        comment_id=reply.comment_id, reply_id=reply.id, mentioned_user_id=user_id_str
-                    )
-                    session.add(mention)
+                mention = WorkflowCommentMention(
+                    comment_id=reply.comment_id, reply_id=reply.id, mentioned_user_id=user_id_str
+                )
+                session.add(mention)
+
+            mention_email_payloads: list[dict[str, str]] = []
+            comment = session.get(WorkflowComment, reply.comment_id)
+            if comment:
+                mention_email_payloads = WorkflowCommentService._build_mention_email_payloads(
+                    session=session,
+                    tenant_id=comment.tenant_id,
+                    app_id=comment.app_id,
+                    mentioner_id=user_id,
+                    mentioned_user_ids=new_mentioned_user_ids,
+                    content=content,
+                )
 
             session.commit()
             session.refresh(reply)  # Refresh to get updated timestamp
+            WorkflowCommentService._dispatch_mention_emails(mention_email_payloads)
 
             return {"id": reply.id, "updated_at": reply.updated_at}
 

api/tasks/mail_workflow_comment_task.py

@@ -0,0 +1,62 @@
+import logging
+import time
+
+import click
+from celery import shared_task
+
+from extensions.ext_mail import mail
+from libs.email_i18n import EmailType, get_email_i18n_service
+
+logger = logging.getLogger(__name__)
+
+
+@shared_task(queue="mail")
+def send_workflow_comment_mention_email_task(
+    language: str,
+    to: str,
+    mentioned_name: str,
+    commenter_name: str,
+    app_name: str,
+    comment_content: str,
+):
+    """
+    Send workflow comment mention email with internationalization support.
+
+    Args:
+        language: Language code for email localization
+        to: Recipient email address
+        mentioned_name: Name of the mentioned user
+        commenter_name: Name of the comment author
+        app_name: Name of the app where the comment was made
+        comment_content: Comment content excerpt
+    """
+    if not mail.is_inited():
+        return
+
+    logger.info(click.style(f"Start workflow comment mention mail to {to}", fg="green"))
+    start_at = time.perf_counter()
+
+    try:
+        email_service = get_email_i18n_service()
+        email_service.send_email(
+            email_type=EmailType.WORKFLOW_COMMENT_MENTION,
+            language_code=language,
+            to=to,
+            template_context={
+                "to": to,
+                "mentioned_name": mentioned_name,
+                "commenter_name": commenter_name,
+                "app_name": app_name,
+                "comment_content": comment_content,
+            },
+        )
+
+        end_at = time.perf_counter()
+        logger.info(
+            click.style(
+                f"Send workflow comment mention mail to {to} succeeded: latency: {end_at - start_at}",
+                fg="green",
+            )
+        )
+    except Exception:
+        logger.exception("workflow comment mention email to %s failed", to)

api/templates/without-brand/workflow_comment_mention_template_en-US.html

@@ -0,0 +1,119 @@
+<!DOCTYPE html>
+<html>
+
+<head>
+  <style>
+    body {
+      font-family: 'Arial', sans-serif;
+      line-height: 16pt;
+      color: #101828;
+      background-color: #e9ebf0;
+      margin: 0;
+      padding: 0;
+    }
+
+    .container {
+      width: 504px;
+      min-height: 374px;
+      margin: 40px auto;
+      padding: 0 48px;
+      background-color: #fcfcfd;
+      border-radius: 16px;
+      border: 1px solid #ffffff;
+      box-shadow: 0px 3px 10px -2px rgba(9, 9, 11, 0.08), 0px 2px 4px -2px rgba(9, 9, 11, 0.06);
+    }
+
+    .header {
+      padding-top: 36px;
+      padding-bottom: 24px;
+    }
+
+    .header img {
+      max-width: 63px;
+      height: auto;
+    }
+
+    .title {
+      margin: 0;
+      padding-top: 8px;
+      padding-bottom: 16px;
+      color: #101828;
+      font-size: 24px;
+      font-family: Inter;
+      font-style: normal;
+      font-weight: 600;
+      line-height: 120%;
+    }
+
+    .description {
+      color: #354052;
+      font-size: 14px;
+      font-family: Inter;
+      font-style: normal;
+      font-weight: 400;
+      line-height: 20px;
+      letter-spacing: -0.07px;
+    }
+
+    .content1 {
+      margin: 0;
+      padding-top: 16px;
+      padding-bottom: 8px;
+    }
+
+    .content2 {
+      margin: 0;
+      padding-bottom: 16px;
+    }
+
+    .comment-box {
+      margin-bottom: 16px;
+      padding: 12px 16px;
+      border-radius: 12px;
+      background-color: #f2f4f7;
+    }
+
+    .comment-text {
+      margin: 0;
+      color: #101828;
+      font-family: Inter;
+      font-size: 14px;
+      font-style: normal;
+      font-weight: 500;
+      line-height: 20px;
+      white-space: pre-wrap;
+      word-break: break-word;
+    }
+
+    .tips {
+      margin: 0;
+      padding-bottom: 24px;
+      color: #354052;
+      font-size: 14px;
+      font-family: Inter;
+      font-style: normal;
+      font-weight: 400;
+      line-height: 20px;
+      letter-spacing: -0.07px;
+    }
+  </style>
+</head>
+
+<body>
+  <div class="container">
+    <div class="header">
+      <img src="https://assets.dify.ai/images/logo.png" alt="Dify Logo" />
+    </div>
+    <p class="title">You were mentioned in a workflow comment</p>
+    <div class="description">
+      <p class="content1">Hi {{ mentioned_name }},</p>
+      <p class="content2">{{ commenter_name }} mentioned you in {{ app_name }}.</p>
+    </div>
+    <div class="comment-box">
+      <p class="comment-text">{{ comment_content }}</p>
+    </div>
+    <p class="tips">Open {{ application_title }} to reply to the comment.</p>
+  </div>
+</body>
+
+</html>

api/templates/without-brand/workflow_comment_mention_template_zh-CN.html

@@ -0,0 +1,119 @@
+<!DOCTYPE html>
+<html>
+
+<head>
+  <style>
+    body {
+      font-family: 'Arial', sans-serif;
+      line-height: 16pt;
+      color: #101828;
+      background-color: #e9ebf0;
+      margin: 0;
+      padding: 0;
+    }
+
+    .container {
+      width: 504px;
+      min-height: 374px;
+      margin: 40px auto;
+      padding: 0 48px;
+      background-color: #fcfcfd;
+      border-radius: 16px;
+      border: 1px solid #ffffff;
+      box-shadow: 0px 3px 10px -2px rgba(9, 9, 11, 0.08), 0px 2px 4px -2px rgba(9, 9, 11, 0.06);
+    }
+
+    .header {
+      padding-top: 36px;
+      padding-bottom: 24px;
+    }
+
+    .header img {
+      max-width: 63px;
+      height: auto;
+    }
+
+    .title {
+      margin: 0;
+      padding-top: 8px;
+      padding-bottom: 16px;
+      color: #101828;
+      font-size: 24px;
+      font-family: Inter;
+      font-style: normal;
+      font-weight: 600;
+      line-height: 120%;
+    }
+
+    .description {
+      color: #354052;
+      font-size: 14px;
+      font-family: Inter;
+      font-style: normal;
+      font-weight: 400;
+      line-height: 20px;
+      letter-spacing: -0.07px;
+    }
+
+    .content1 {
+      margin: 0;
+      padding-top: 16px;
+      padding-bottom: 8px;
+    }
+
+    .content2 {
+      margin: 0;
+      padding-bottom: 16px;
+    }
+
+    .comment-box {
+      margin-bottom: 16px;
+      padding: 12px 16px;
+      border-radius: 12px;
+      background-color: #f2f4f7;
+    }
+
+    .comment-text {
+      margin: 0;
+      color: #101828;
+      font-family: Inter;
+      font-size: 14px;
+      font-style: normal;
+      font-weight: 500;
+      line-height: 20px;
+      white-space: pre-wrap;
+      word-break: break-word;
+    }
+
+    .tips {
+      margin: 0;
+      padding-bottom: 24px;
+      color: #354052;
+      font-size: 14px;
+      font-family: Inter;
+      font-style: normal;
+      font-weight: 400;
+      line-height: 20px;
+      letter-spacing: -0.07px;
+    }
+  </style>
+</head>
+
+<body>
+  <div class="container">
+    <div class="header">
+      <img src="https://assets.dify.ai/images/logo.png" alt="Dify Logo" />
+    </div>
+    <p class="title">你在工作流评论中被提及</p>
+    <div class="description">
+      <p class="content1">你好，{{ mentioned_name }}：</p>
+      <p class="content2">{{ commenter_name }} 在 {{ app_name }} 中提及了你。</p>
+    </div>
+    <div class="comment-box">
+      <p class="comment-text">{{ comment_content }}</p>
+    </div>
+    <p class="tips">请在 {{ application_title }} 中查看并回复此评论。</p>
+  </div>
+</body>
+
+</html>

api/templates/workflow_comment_mention_template_en-US.html

@@ -0,0 +1,119 @@
+<!DOCTYPE html>
+<html>
+
+<head>
+  <style>
+    body {
+      font-family: 'Arial', sans-serif;
+      line-height: 16pt;
+      color: #101828;
+      background-color: #e9ebf0;
+      margin: 0;
+      padding: 0;
+    }
+
+    .container {
+      width: 504px;
+      min-height: 374px;
+      margin: 40px auto;
+      padding: 0 48px;
+      background-color: #fcfcfd;
+      border-radius: 16px;
+      border: 1px solid #ffffff;
+      box-shadow: 0px 3px 10px -2px rgba(9, 9, 11, 0.08), 0px 2px 4px -2px rgba(9, 9, 11, 0.06);
+    }
+
+    .header {
+      padding-top: 36px;
+      padding-bottom: 24px;
+    }
+
+    .header img {
+      max-width: 63px;
+      height: auto;
+    }
+
+    .title {
+      margin: 0;
+      padding-top: 8px;
+      padding-bottom: 16px;
+      color: #101828;
+      font-size: 24px;
+      font-family: Inter;
+      font-style: normal;
+      font-weight: 600;
+      line-height: 120%;
+    }
+
+    .description {
+      color: #354052;
+      font-size: 14px;
+      font-family: Inter;
+      font-style: normal;
+      font-weight: 400;
+      line-height: 20px;
+      letter-spacing: -0.07px;
+    }
+
+    .content1 {
+      margin: 0;
+      padding-top: 16px;
+      padding-bottom: 8px;
+    }
+
+    .content2 {
+      margin: 0;
+      padding-bottom: 16px;
+    }
+
+    .comment-box {
+      margin-bottom: 16px;
+      padding: 12px 16px;
+      border-radius: 12px;
+      background-color: #f2f4f7;
+    }
+
+    .comment-text {
+      margin: 0;
+      color: #101828;
+      font-family: Inter;
+      font-size: 14px;
+      font-style: normal;
+      font-weight: 500;
+      line-height: 20px;
+      white-space: pre-wrap;
+      word-break: break-word;
+    }
+
+    .tips {
+      margin: 0;
+      padding-bottom: 24px;
+      color: #354052;
+      font-size: 14px;
+      font-family: Inter;
+      font-style: normal;
+      font-weight: 400;
+      line-height: 20px;
+      letter-spacing: -0.07px;
+    }
+  </style>
+</head>
+
+<body>
+  <div class="container">
+    <div class="header">
+      <img src="https://assets.dify.ai/images/logo.png" alt="Dify Logo" />
+    </div>
+    <p class="title">You were mentioned in a workflow comment</p>
+    <div class="description">
+      <p class="content1">Hi {{ mentioned_name }},</p>
+      <p class="content2">{{ commenter_name }} mentioned you in {{ app_name }}.</p>
+    </div>
+    <div class="comment-box">
+      <p class="comment-text">{{ comment_content }}</p>
+    </div>
+    <p class="tips">Open {{ application_title }} to reply to the comment.</p>
+  </div>
+</body>
+
+</html>

api/templates/workflow_comment_mention_template_zh-CN.html

@@ -0,0 +1,119 @@
+<!DOCTYPE html>
+<html>
+
+<head>
+  <style>
+    body {
+      font-family: 'Arial', sans-serif;
+      line-height: 16pt;
+      color: #101828;
+      background-color: #e9ebf0;
+      margin: 0;
+      padding: 0;
+    }
+
+    .container {
+      width: 504px;
+      min-height: 374px;
+      margin: 40px auto;
+      padding: 0 48px;
+      background-color: #fcfcfd;
+      border-radius: 16px;
+      border: 1px solid #ffffff;
+      box-shadow: 0px 3px 10px -2px rgba(9, 9, 11, 0.08), 0px 2px 4px -2px rgba(9, 9, 11, 0.06);
+    }
+
+    .header {
+      padding-top: 36px;
+      padding-bottom: 24px;
+    }
+
+    .header img {
+      max-width: 63px;
+      height: auto;
+    }
+
+    .title {
+      margin: 0;
+      padding-top: 8px;
+      padding-bottom: 16px;
+      color: #101828;
+      font-size: 24px;
+      font-family: Inter;
+      font-style: normal;
+      font-weight: 600;
+      line-height: 120%;
+    }
+
+    .description {
+      color: #354052;
+      font-size: 14px;
+      font-family: Inter;
+      font-style: normal;
+      font-weight: 400;
+      line-height: 20px;
+      letter-spacing: -0.07px;
+    }
+
+    .content1 {
+      margin: 0;
+      padding-top: 16px;
+      padding-bottom: 8px;
+    }
+
+    .content2 {
+      margin: 0;
+      padding-bottom: 16px;
+    }
+
+    .comment-box {
+      margin-bottom: 16px;
+      padding: 12px 16px;
+      border-radius: 12px;
+      background-color: #f2f4f7;
+    }
+
+    .comment-text {
+      margin: 0;
+      color: #101828;
+      font-family: Inter;
+      font-size: 14px;
+      font-style: normal;
+      font-weight: 500;
+      line-height: 20px;
+      white-space: pre-wrap;
+      word-break: break-word;
+    }
+
+    .tips {
+      margin: 0;
+      padding-bottom: 24px;
+      color: #354052;
+      font-size: 14px;
+      font-family: Inter;
+      font-style: normal;
+      font-weight: 400;
+      line-height: 20px;
+      letter-spacing: -0.07px;
+    }
+  </style>
+</head>
+
+<body>
+  <div class="container">
+    <div class="header">
+      <img src="https://assets.dify.ai/images/logo.png" alt="Dify Logo" />
+    </div>
+    <p class="title">你在工作流评论中被提及</p>
+    <div class="description">
+      <p class="content1">你好，{{ mentioned_name }}：</p>
+      <p class="content2">{{ commenter_name }} 在 {{ app_name }} 中提及了你。</p>
+    </div>
+    <div class="comment-box">
+      <p class="comment-text">{{ comment_content }}</p>
+    </div>
+    <p class="tips">请在 {{ application_title }} 中查看并回复此评论。</p>
+  </div>
+</body>
+
+</html>

api/tests/unit_tests/libs/test_email_i18n.py

@@ -503,6 +503,7 @@ class TestEmailI18nIntegration:
             EmailType.ACCOUNT_DELETION_VERIFICATION,
             EmailType.QUEUE_MONITOR_ALERT,
             EmailType.DOCUMENT_CLEAN_NOTIFY,
+            EmailType.WORKFLOW_COMMENT_MENTION,
         ]
 
         for email_type in expected_types:

api/tests/unit_tests/services/test_workflow_comment_service.py

@@ -15,8 +15,12 @@ def mock_session(monkeypatch: pytest.MonkeyPatch) -> Mock:
     context_manager.__exit__.return_value = False
     mock_db = MagicMock()
     mock_db.engine = Mock()
+    empty_scalars = Mock()
+    empty_scalars.all.return_value = []
+    session.scalars.return_value = empty_scalars
     monkeypatch.setattr(service_module, "Session", Mock(return_value=context_manager))
     monkeypatch.setattr(service_module, "db", mock_db)
+    monkeypatch.setattr(service_module.send_workflow_comment_mention_email_task, "delay", Mock())
     return session
 
 
@@ -35,6 +39,40 @@ class TestWorkflowCommentService:
         with pytest.raises(ValueError):
             WorkflowCommentService._validate_content("a" * 1001)
 
+    def test_build_mention_email_payloads_skips_accounts_without_email(self, mock_session: Mock) -> None:
+        account_without_email = Mock()
+        account_without_email.email = None
+        account_without_email.name = "No Email"
+        account_without_email.interface_language = "en-US"
+
+        account_with_email = Mock()
+        account_with_email.email = "user@example.com"
+        account_with_email.name = ""
+        account_with_email.interface_language = None
+
+        mock_session.scalar.side_effect = ["My App", "Commenter"]
+        mock_session.scalars.return_value = _mock_scalars([account_without_email, account_with_email])
+
+        payloads = WorkflowCommentService._build_mention_email_payloads(
+            session=mock_session,
+            tenant_id="tenant-1",
+            app_id="app-1",
+            mentioner_id="user-1",
+            mentioned_user_ids=["user-2"],
+            content="hello",
+        )
+
+        assert payloads == [
+            {
+                "language": "en-US",
+                "to": "user@example.com",
+                "mentioned_name": "user@example.com",
+                "commenter_name": "Commenter",
+                "app_name": "My App",
+                "comment_content": "hello",
+            }
+        ]
+
     def test_create_comment_creates_mentions(self, mock_session: Mock) -> None:
         comment = Mock()
         comment.id = "comment-1"
@@ -110,6 +148,37 @@ class TestWorkflowCommentService:
         assert mock_session.add.call_count == 1
         mock_session.commit.assert_called_once()
 
+    def test_update_comment_notifies_only_new_mentions(self, mock_session: Mock) -> None:
+        comment = Mock()
+        comment.id = "comment-1"
+        comment.created_by = "owner"
+        mock_session.scalar.return_value = comment
+
+        existing_mention = Mock()
+        existing_mention.mentioned_user_id = "user-2"
+        mock_session.scalars.return_value = _mock_scalars([existing_mention])
+
+        with (
+            patch.object(service_module, "uuid_value", side_effect=[True, True]),
+            patch.object(
+                WorkflowCommentService,
+                "_build_mention_email_payloads",
+                return_value=[],
+            ) as build_payloads_mock,
+            patch.object(WorkflowCommentService, "_dispatch_mention_emails") as dispatch_mock,
+        ):
+            WorkflowCommentService.update_comment(
+                tenant_id="tenant-1",
+                app_id="app-1",
+                comment_id="comment-1",
+                user_id="owner",
+                content="updated",
+                mentioned_user_ids=["user-2", "user-3"],
+            )
+
+        assert build_payloads_mock.call_args.kwargs["mentioned_user_ids"] == ["user-3"]
+        dispatch_mock.assert_called_once_with([])
+
     def test_delete_comment_raises_forbidden(self, mock_session: Mock) -> None:
         comment = Mock()
         comment.created_by = "owner"