diff --git a/ansible/mysql-deploy.yml b/ansible/mysql-deploy.yml
index ceb7fbb..4bbfb2d 100644
--- a/ansible/mysql-deploy.yml
+++ b/ansible/mysql-deploy.yml
@@ -8,9 +8,18 @@
     # --- identity ---
     mysql_instance: "{{ instance_name }}"
     mysql_version_value: "{{ mysql_version | default('8.0') }}"
+    # 版本包映射：8.0 用 Ubuntu 24.04 自带源（精确锁版）；8.4 用 MySQL 官方 APT 源的 LTS 组件
+    # （noble 自带源无 8.4，官方源组件内即为该系列，不再锁小版本）。
+    # 5.6/5.7 已官方 EOL 且 Ubuntu 24.04 无可用 apt 包，明确不纳入白名单。
     mysql_package_map:
-      "8.0": "mysql-server=8.0.46-0ubuntu0.24.04.3"
-    mysql_package_name: "{{ mysql_package_map[mysql_version_value] }}"
+      "8.0":
+        package: "mysql-server=8.0.46-0ubuntu0.24.04.3"
+        repo_component: ""
+      "8.4":
+        package: "mysql-community-server"
+        repo_component: "mysql-8.4-lts"
+    mysql_package_name: "{{ (mysql_package_map[mysql_version_value] | default({})).package | default('') }}"
+    mysql_repo_component: "{{ (mysql_package_map[mysql_version_value] | default({})).repo_component | default('') }}"
 
     # --- platform-allocated inputs (safe fallbacks when not passed in) ---
     # 端口池 13306–13999：平台从池分配并传入；未传时兜底池首端口，占用探测在目标机执行。
@@ -132,13 +141,46 @@
           host-wide Σ-quota budgeting is the platform's responsibility, this is a last-resort guard.
 
   tasks:
-    - name: Detect an existing Ubuntu MySQL package
-      ansible.builtin.command: dpkg-query -W mysql-server
+    - name: Detect an existing MySQL server package
+      ansible.builtin.command: dpkg-query -W -f '${Package}=${Version}\n' mysql-server mysql-community-server
       register: mysql_package_before
       failed_when: false
       changed_when: false
 
-    - name: Install Ubuntu MySQL package
+    - name: Resolve the installed MySQL server version
+      ansible.builtin.set_fact:
+        mysql_installed_version: >-
+          {{ (mysql_package_before.stdout_lines | select('search', '=') | list
+              | first | default('')).split('=') | last }}
+
+    # /usr 下的 mysqld/mysql 二进制全机共享，一台主机只能承载一个 MySQL 版本系列。
+    - name: Enforce host-level MySQL series consistency
+      ansible.builtin.assert:
+        that:
+          - mysql_installed_version == '' or mysql_installed_version.startswith(mysql_version_value ~ '.')
+        fail_msg: >-
+          Host already runs MySQL {{ mysql_installed_version }} but {{ mysql_version_value }} was requested;
+          native binaries under /usr are shared host-wide, so one host serves exactly one MySQL series.
+
+    - name: Install the MySQL APT repository signing key
+      ansible.builtin.get_url:
+        url: https://repo.mysql.com/RPM-GPG-KEY-mysql-2023
+        dest: /etc/apt/keyrings/mysql.asc
+        owner: root
+        group: root
+        mode: '0644'
+      when: mysql_repo_component != ''
+
+    - name: Configure the MySQL APT repository component
+      ansible.builtin.apt_repository:
+        repo: >-
+          deb [signed-by=/etc/apt/keyrings/mysql.asc]
+          http://repo.mysql.com/apt/ubuntu {{ ansible_distribution_release }} {{ mysql_repo_component }}
+        filename: xinfra-mysql-delivery
+        state: present
+      when: mysql_repo_component != ''
+
+    - name: Install the MySQL server package
       ansible.builtin.apt:
         name: "{{ mysql_package_name }}"
         state: present
@@ -150,7 +192,7 @@
         name: mysql.service
         state: stopped
         enabled: false
-      when: mysql_package_before.rc != 0
+      when: mysql_installed_version == ''
 
     - name: Check for the bundled MySQL AppArmor profile
       ansible.builtin.stat:
diff --git a/ansible/templates/mysql-instance.cnf.j2 b/ansible/templates/mysql-instance.cnf.j2
index c295279..da6e3cf 100644
--- a/ansible/templates/mysql-instance.cnf.j2
+++ b/ansible/templates/mysql-instance.cnf.j2
@@ -66,7 +66,10 @@ loose-mysqlx=0
 {% if topology == 'mgr_3' %}
 # --- Group Replication (config-ready; runtime bootstrap handled out-of-band) ---
 plugin-load-add=group_replication.so
+{% if mysql_version_value != '8.4' %}
+{# deprecated since 8.0.26 and removed in 8.3+; only inject for older series #}
 transaction-write-set-extraction=XXHASH64
+{% endif %}
 loose-group-replication-group-name={{ mgr_group_name }}
 loose-group-replication-start-on-boot=OFF
 loose-group-replication-local-address={{ ansible_host | default(inventory_hostname) }}:{{ mysql_gr_port_value }}
diff --git a/server/internal/service/delivery.go b/server/internal/service/delivery.go
index 1c6911c..f40a8dd 100644
--- a/server/internal/service/delivery.go
+++ b/server/internal/service/delivery.go
@@ -286,8 +286,9 @@ func (s *DeliveryService) CreateTask(ctx context.Context, userID uint64, isAdmin
 	return &task, false, nil
 }
 
-// 版本白名单与 playbook 的 mysql_package_map 保持同步。
-var supportedMySQLVersions = map[string]bool{"8.0": true}
+// 版本白名单与 playbook 的 mysql_package_map 保持同步：
+// 8.0 走 Ubuntu 自带源，8.4 走 MySQL 官方 APT 源；5.6/5.7 已 EOL 且无 noble 包，不支持。
+var supportedMySQLVersions = map[string]bool{"8.0": true, "8.4": true}
 
 // 拓扑白名单：playbook 已支持 primary_replica/mgr_3 的配置渲染，
 // 但调度器仍是单主机模型且复制编排未自动化，本期仅放开 standalone。
@@ -319,7 +320,7 @@ func validateDeliveryInput(input MySQLDeliveryInput, dataDisks []string) error {
 		return fmt.Errorf("requested resources are outside the supported range (memory: 2048-65536 MiB, storage: 20-2000 GiB)")
 	}
 	if input.MySQLVersion != "" && !supportedMySQLVersions[input.MySQLVersion] {
-		return fmt.Errorf("unsupported mysql_version %q, supported: 8.0", input.MySQLVersion)
+		return fmt.Errorf("unsupported mysql_version %q, supported: 8.0, 8.4 (5.6/5.7 are EOL and have no Ubuntu 24.04 packages)", input.MySQLVersion)
 	}
 	if input.Topology != "" && !supportedTopologies[input.Topology] {
 		return fmt.Errorf("unsupported topology %q, supported: standalone (primary_replica/mgr_3 pending scheduler support)", input.Topology)
diff --git a/server/internal/service/delivery_test.go b/server/internal/service/delivery_test.go
index 508b46f..f929cba 100644
--- a/server/internal/service/delivery_test.go
+++ b/server/internal/service/delivery_test.go
@@ -37,6 +37,11 @@ func TestValidateDeliveryInput(t *testing.T) {
 	if err := validateDeliveryInput(namedZone, dataDisks); err != nil {
 		t.Fatalf("named timezone rejected: %v", err)
 	}
+	lts := valid
+	lts.MySQLVersion = "8.4"
+	if err := validateDeliveryInput(lts, dataDisks); err != nil {
+		t.Fatalf("8.4 LTS rejected: %v", err)
+	}
 	for name, mutate := range map[string]func(*MySQLDeliveryInput){
 		"uppercase namespace":   func(in *MySQLDeliveryInput) { in.Namespace = "Team-A" },
 		"bad instance":          func(in *MySQLDeliveryInput) { in.InstanceName = "mysql_01" },
@@ -45,6 +50,7 @@ func TestValidateDeliveryInput(t *testing.T) {
 		"too little storage":    func(in *MySQLDeliveryInput) { in.StorageGi = 10 },
 		"too much storage":      func(in *MySQLDeliveryInput) { in.StorageGi = 4000 },
 		"unsupported version":   func(in *MySQLDeliveryInput) { in.MySQLVersion = "5.7" },
+		"eol version":           func(in *MySQLDeliveryInput) { in.MySQLVersion = "5.6" },
 		"unsupported topology":  func(in *MySQLDeliveryInput) { in.Topology = "mgr_3" },
 		"port below pool":       func(in *MySQLDeliveryInput) { in.MySQLPort = 3307 },
 		"port above pool":       func(in *MySQLDeliveryInput) { in.MySQLPort = 14000 },