diff --git a/src/components/dialog/content/LoadWorkflowWarning.vue b/src/components/dialog/content/LoadWorkflowWarning.vue
index 543965a8b..43ab5cb60 100644
--- a/src/components/dialog/content/LoadWorkflowWarning.vue
+++ b/src/components/dialog/content/LoadWorkflowWarning.vue
@@ -51,6 +51,7 @@
 import Button from 'primevue/button'
 import ListBox from 'primevue/listbox'
 import { computed, onMounted, ref } from 'vue'
+import { useI18n } from 'vue-i18n'
 
 import NoResultsPlaceholder from '@/components/common/NoResultsPlaceholder.vue'
 import MissingCoreNodesMessage from '@/components/dialog/content/MissingCoreNodesMessage.vue'
@@ -58,6 +59,12 @@ import { useMissingNodes } from '@/composables/nodePack/useMissingNodes'
 import { useComfyManagerService } from '@/services/comfyManagerService'
 import { useDialogService } from '@/services/dialogService'
 import { useComfyManagerStore } from '@/stores/comfyManagerStore'
+import { useCommandStore } from '@/stores/commandStore'
+import {
+  ManagerUIState,
+  useManagerStateStore
+} from '@/stores/managerStateStore'
+import { useToastStore } from '@/stores/toastStore'
 import type { MissingNodeType } from '@/types/comfy'
 import { ManagerTab } from '@/types/comfyManagerTypes'
 
@@ -103,10 +110,37 @@ const uniqueNodes = computed(() => {
     })
 })
 
-const openManager = () => {
-  useDialogService().showManagerDialog({
-    initialTab: ManagerTab.Missing
-  })
+const managerStateStore = useManagerStateStore()
+
+const openManager = async () => {
+  const state = managerStateStore.managerUIState
+
+  switch (state) {
+    case ManagerUIState.DISABLED:
+      useDialogService().showSettingsDialog('extension')
+      break
+
+    case ManagerUIState.LEGACY_UI:
+      try {
+        await useCommandStore().execute('Comfy.Manager.Menu.ToggleVisibility')
+      } catch {
+        // If legacy command doesn't exist, show toast
+        const { t } = useI18n()
+        useToastStore().add({
+          severity: 'error',
+          summary: t('g.error'),
+          detail: t('manager.legacyMenuNotAvailable'),
+          life: 3000
+        })
+      }
+      break
+
+    case ManagerUIState.NEW_UI:
+      useDialogService().showManagerDialog({
+        initialTab: ManagerTab.Missing
+      })
+      break
+  }
 }
 
 onMounted(async () => {
diff --git a/src/components/topbar/CommandMenubar.vue b/src/components/topbar/CommandMenubar.vue
index d64cf92e5..56e06ac10 100644
--- a/src/components/topbar/CommandMenubar.vue
+++ b/src/components/topbar/CommandMenubar.vue
@@ -107,9 +107,12 @@ import SubgraphBreadcrumb from '@/components/breadcrumb/SubgraphBreadcrumb.vue'
 import SettingDialogContent from '@/components/dialog/content/SettingDialogContent.vue'
 import SettingDialogHeader from '@/components/dialog/header/SettingDialogHeader.vue'
 import { useDialogService } from '@/services/dialogService'
-import { useAboutPanelStore } from '@/stores/aboutPanelStore'
 import { useCommandStore } from '@/stores/commandStore'
 import { useDialogStore } from '@/stores/dialogStore'
+import {
+  ManagerUIState,
+  useManagerStateStore
+} from '@/stores/managerStateStore'
 import { useMenuItemStore } from '@/stores/menuItemStore'
 import { useSettingStore } from '@/stores/settingStore'
 import { useColorPaletteStore } from '@/stores/workspace/colorPaletteStore'
@@ -121,7 +124,6 @@ const colorPaletteStore = useColorPaletteStore()
 const menuItemsStore = useMenuItemStore()
 const commandStore = useCommandStore()
 const dialogStore = useDialogStore()
-const aboutPanelStore = useAboutPanelStore()
 const settingStore = useSettingStore()
 const { t } = useI18n()
 
@@ -157,23 +159,28 @@ const showSettings = (defaultPanel?: string) => {
   })
 }
 
-// Temporary duplicated from LoadWorkflowWarning.vue
-// Determines if ComfyUI-Manager is installed by checking for its badge in the about panel
-// This allows us to conditionally show the Manager button only when the extension is available
-// TODO: Remove this check when Manager functionality is fully migrated into core
-const isManagerInstalled = computed(() => {
-  return aboutPanelStore.badges.some(
-    (badge) =>
-      badge.label.includes('ComfyUI-Manager') ||
-      badge.url.includes('ComfyUI-Manager')
-  )
-})
+const managerStateStore = useManagerStateStore()
 
-const showManageExtensions = () => {
-  if (isManagerInstalled.value) {
-    useDialogService().showManagerDialog()
-  } else {
-    showSettings('extension')
+const showManageExtensions = async () => {
+  const state = managerStateStore.managerUIState
+
+  switch (state) {
+    case ManagerUIState.DISABLED:
+      showSettings('extension')
+      break
+
+    case ManagerUIState.LEGACY_UI:
+      try {
+        await commandStore.execute('Comfy.Manager.Menu.ToggleVisibility')
+      } catch {
+        // If legacy command doesn't exist, fall back to extensions panel
+        showSettings('extension')
+      }
+      break
+
+    case ManagerUIState.NEW_UI:
+      useDialogService().showManagerDialog()
+      break
   }
 }
 
diff --git a/src/composables/useCoreCommands.ts b/src/composables/useCoreCommands.ts
index 2ad3e5653..e0509586d 100644
--- a/src/composables/useCoreCommands.ts
+++ b/src/composables/useCoreCommands.ts
@@ -760,12 +760,8 @@ export function useCoreCommands(): ComfyCommand[] {
             useCommandStore()
               .execute('Comfy.Manager.Menu.ToggleVisibility')
               .catch(() => {
-                toastStore.add({
-                  severity: 'error',
-                  summary: t('g.error'),
-                  detail: t('manager.legacyMenuNotAvailable'),
-                  life: 3000
-                })
+                // If legacy command doesn't exist, fall back to extensions panel
+                dialogService.showSettingsDialog('extension')
               })
             break
 
@@ -780,10 +776,32 @@ export function useCoreCommands(): ComfyCommand[] {
       icon: 'pi pi-sync',
       label: 'Check for Custom Node Updates',
       versionAdded: '1.17.0',
-      function: () => {
-        dialogService.showManagerDialog({
-          initialTab: ManagerTab.UpdateAvailable
-        })
+      function: async () => {
+        const managerStore = useManagerStateStore()
+        const state = managerStore.managerUIState
+
+        switch (state) {
+          case ManagerUIState.DISABLED:
+            dialogService.showSettingsDialog('extension')
+            break
+
+          case ManagerUIState.LEGACY_UI:
+            try {
+              await useCommandStore().execute(
+                'Comfy.Manager.Menu.ToggleVisibility'
+              )
+            } catch {
+              // If legacy command doesn't exist, fall back to extensions panel
+              dialogService.showSettingsDialog('extension')
+            }
+            break
+
+          case ManagerUIState.NEW_UI:
+            dialogService.showManagerDialog({
+              initialTab: ManagerTab.UpdateAvailable
+            })
+            break
+        }
       }
     },
     {
@@ -791,10 +809,33 @@ export function useCoreCommands(): ComfyCommand[] {
       icon: 'pi pi-exclamation-circle',
       label: 'Install Missing Custom Nodes',
       versionAdded: '1.17.0',
-      function: () => {
-        dialogService.showManagerDialog({
-          initialTab: ManagerTab.Missing
-        })
+      function: async () => {
+        const managerStore = useManagerStateStore()
+        const state = managerStore.managerUIState
+
+        switch (state) {
+          case ManagerUIState.DISABLED:
+            // When manager is disabled, open the extensions panel in settings
+            dialogService.showSettingsDialog('extension')
+            break
+
+          case ManagerUIState.LEGACY_UI:
+            try {
+              await useCommandStore().execute(
+                'Comfy.Manager.Menu.ToggleVisibility'
+              )
+            } catch {
+              // If legacy command doesn't exist, fall back to extensions panel
+              dialogService.showSettingsDialog('extension')
+            }
+            break
+
+          case ManagerUIState.NEW_UI:
+            dialogService.showManagerDialog({
+              initialTab: ManagerTab.Missing
+            })
+            break
+        }
       }
     },
     {
diff --git a/src/services/comfyManagerService.ts b/src/services/comfyManagerService.ts
index 330d5dd0f..bed1f9eed 100644
--- a/src/services/comfyManagerService.ts
+++ b/src/services/comfyManagerService.ts
@@ -1,6 +1,7 @@
 import axios, { AxiosError, AxiosResponse } from 'axios'
 import { ref } from 'vue'
 
+import { ServerFeatureFlag } from '@/composables/useFeatureFlags'
 import { api } from '@/scripts/api'
 import {
   type InstallPackParams,
@@ -35,8 +36,12 @@ enum ManagerRoute {
   IS_LEGACY_MANAGER_UI = 'manager/is_legacy_manager_ui'
 }
 
+// Create axios client with conditional v2 prefix based on manager v4 support
+const supportsV4 = api.getServerFeature(ServerFeatureFlag.MANAGER_SUPPORTS_V4)
+const baseURL = supportsV4 ? api.apiURL('/v2/') : api.apiURL('/')
+
 const managerApiClient = axios.create({
-  baseURL: api.apiURL('/v2/'),
+  baseURL,
   headers: {
     'Content-Type': 'application/json'
   }