diff --git a/apps/admin-web/src/components/CoverSourceSelector.vue b/apps/admin-web/src/components/CoverSourceSelector.vue
index 4c690ed..bf94a31 100644
--- a/apps/admin-web/src/components/CoverSourceSelector.vue
+++ b/apps/admin-web/src/components/CoverSourceSelector.vue
@@ -1,5 +1,6 @@
 <script setup lang="ts">
 import { imagesApi } from '@/lib/api'
+import { useCompanyStore } from '@/stores/company'
 import type { ScheduleCoverMode, ScheduleCoverRandomScope } from '@geo/shared-types'
 import { useQuery } from '@tanstack/vue-query'
 import { computed, watch } from 'vue'
@@ -24,10 +25,12 @@ const emit = defineEmits<{
 }>()
 
 const { t } = useI18n()
+const companyStore = useCompanyStore()
+const currentBrandId = computed(() => companyStore.currentBrandId)
 
 const foldersQuery = useQuery({
-  queryKey: ['images', 'folders', 'cover-source'],
-  enabled: computed(() => !props.disabled),
+  queryKey: computed(() => ['images', 'folders', 'cover-source', currentBrandId.value]),
+  enabled: computed(() => !props.disabled && Boolean(currentBrandId.value)),
   queryFn: () => imagesApi.listFolders(),
 })
 
@@ -38,6 +41,13 @@ const folderOptions = computed(() =>
   })),
 )
 
+watch(
+  currentBrandId,
+  () => {
+    emit('update:randomFolderId', null)
+  },
+)
+
 watch(
   () => props.mode,
   (mode) => {
diff --git a/apps/admin-web/src/components/ImageLibraryPicker.vue b/apps/admin-web/src/components/ImageLibraryPicker.vue
index 181fb12..46f2fba 100644
--- a/apps/admin-web/src/components/ImageLibraryPicker.vue
+++ b/apps/admin-web/src/components/ImageLibraryPicker.vue
@@ -1,6 +1,7 @@
 <script setup lang="ts">
 import { imagesApi } from '@/lib/api'
 import { formatBytes, formatPercentage } from '@/lib/display'
+import { useCompanyStore } from '@/stores/company'
 import type { ImageAssetItem } from '@geo/shared-types'
 import { useQuery } from '@tanstack/vue-query'
 import { computed, ref, watch } from 'vue'
@@ -20,6 +21,8 @@ const emit = defineEmits<{
 }>()
 
 const { t } = useI18n()
+const companyStore = useCompanyStore()
+const currentBrandId = computed(() => companyStore.currentBrandId)
 
 // State
 const selectedFolderId = ref<number | null>(null)
@@ -31,7 +34,8 @@ const selectedId = ref<number | null>(null)
 
 // Queries
 const foldersQuery = useQuery({
-  queryKey: ['images', 'folders'],
+  queryKey: computed(() => ['images', 'folders', currentBrandId.value]),
+  enabled: computed(() => Boolean(currentBrandId.value)),
   queryFn: () => imagesApi.listFolders(),
 })
 
@@ -40,6 +44,7 @@ const imagesQuery = useQuery({
     'images',
     'list',
     'picker',
+    currentBrandId.value,
     {
       folder_id: selectedFolderId.value,
       q: debouncedSearch.value,
@@ -47,6 +52,7 @@ const imagesQuery = useQuery({
       page_size: pageSize.value,
     },
   ]),
+  enabled: computed(() => Boolean(currentBrandId.value)),
   queryFn: () =>
     imagesApi.list({
       folder_id: selectedFolderId.value ?? undefined,
@@ -77,6 +83,12 @@ watch(searchKeyword, () => {
   }, 300)
 })
 
+watch(currentBrandId, () => {
+  selectedFolderId.value = null
+  selectedId.value = null
+  currentPage.value = 1
+})
+
 function handleSelect(image: ImageAssetItem) {
   selectedId.value = image.id
   emit('select', image)
diff --git a/apps/admin-web/src/components/KnowledgeDetailDrawer.vue b/apps/admin-web/src/components/KnowledgeDetailDrawer.vue
index 6dc3154..fdb2900 100644
--- a/apps/admin-web/src/components/KnowledgeDetailDrawer.vue
+++ b/apps/admin-web/src/components/KnowledgeDetailDrawer.vue
@@ -5,6 +5,7 @@ import { computed, watch } from 'vue'
 import MarkdownPreview from '@/components/MarkdownPreview.vue'
 import { knowledgeApi } from '@/lib/api'
 import { formatDateTime } from '@/lib/display'
+import { useCompanyStore } from '@/stores/company'
 
 const props = defineProps<{
   open: boolean
@@ -16,10 +17,12 @@ const emit = defineEmits<{
 }>()
 
 const queryClient = useQueryClient()
-const enabled = computed(() => props.open && Boolean(props.itemId))
+const companyStore = useCompanyStore()
+const currentBrandId = computed(() => companyStore.currentBrandId)
+const enabled = computed(() => props.open && Boolean(props.itemId) && Boolean(currentBrandId.value))
 
 const detailQuery = useQuery({
-  queryKey: computed(() => ['knowledge', 'detail', props.itemId]),
+  queryKey: computed(() => ['knowledge', 'detail', currentBrandId.value, props.itemId]),
   enabled,
   queryFn: () => knowledgeApi.detail(props.itemId as number),
 })
diff --git a/apps/admin-web/src/components/KnowledgeGroupSelect.vue b/apps/admin-web/src/components/KnowledgeGroupSelect.vue
index e4a755a..54f3bb2 100644
--- a/apps/admin-web/src/components/KnowledgeGroupSelect.vue
+++ b/apps/admin-web/src/components/KnowledgeGroupSelect.vue
@@ -4,6 +4,7 @@ import { useQuery } from '@tanstack/vue-query'
 import { computed } from 'vue'
 
 import { knowledgeApi } from '@/lib/api'
+import { useCompanyStore } from '@/stores/company'
 
 interface TreeNode {
   title: string
@@ -29,8 +30,12 @@ const emit = defineEmits<{
   'update:modelValue': [value: number[]]
 }>()
 
+const companyStore = useCompanyStore()
+const currentBrandId = computed(() => companyStore.currentBrandId)
+
 const groupsQuery = useQuery({
-  queryKey: ['knowledge', 'groups', 'selector'],
+  queryKey: computed(() => ['knowledge', 'groups', 'selector', currentBrandId.value]),
+  enabled: computed(() => Boolean(currentBrandId.value)),
   queryFn: () => knowledgeApi.listGroups(),
 })
 
diff --git a/apps/admin-web/src/lib/api.ts b/apps/admin-web/src/lib/api.ts
index 0722cdd..e871601 100644
--- a/apps/admin-web/src/lib/api.ts
+++ b/apps/admin-web/src/lib/api.ts
@@ -355,6 +355,8 @@ const currentBrandScopedPathPatterns = [
   /^\/api\/tenant\/enterprise-sites\/[^/]+\/publish(?:\/|$)/,
   /^\/api\/tenant\/media-supply\/orders(?:\/|$)/,
   /^\/api\/tenant\/prompt-rules(?:\/|$)/,
+  /^\/api\/tenant\/knowledge(?:\/|$)/,
+  /^\/api\/tenant\/images(?:\/|$)/,
 ]
 
 function shouldAttachCurrentBrandHeader(url: unknown): boolean {
@@ -362,6 +364,9 @@ function shouldAttachCurrentBrandHeader(url: unknown): boolean {
     return false
   }
   const pathname = normalizeRequestPath(url)
+  if (pathname === '/api/tenant/images/storage-usage') {
+    return false
+  }
   return currentBrandScopedPathPatterns.some((pattern) => pattern.test(pathname))
 }
 
diff --git a/apps/admin-web/src/views/ImagesView.vue b/apps/admin-web/src/views/ImagesView.vue
index 20e4fb3..5d585ea 100644
--- a/apps/admin-web/src/views/ImagesView.vue
+++ b/apps/admin-web/src/views/ImagesView.vue
@@ -18,11 +18,14 @@ import { imagesApi } from '@/lib/api'
 import { formatBytes, formatDateTime, formatPercentage } from '@/lib/display'
 import { formatError } from '@/lib/errors'
 import { IMAGE_UPLOAD_ACCEPT, useImageUploadProgress } from '@/lib/image-webp'
+import { useCompanyStore } from '@/stores/company'
 import type { ImageAssetItem, ImageFolder } from '@geo/shared-types'
 
 const { t } = useI18n()
 const queryClient = useQueryClient()
 const imageUploadProgress = useImageUploadProgress()
+const companyStore = useCompanyStore()
+const currentBrandId = computed(() => companyStore.currentBrandId)
 
 // State
 const selectedFolderId = ref<number | null>(null) // null means "All" or is handled by folders query
@@ -51,7 +54,8 @@ const fileInput = ref<HTMLInputElement | null>(null)
 
 // Queries
 const foldersQuery = useQuery({
-  queryKey: ['images', 'folders'],
+  queryKey: computed(() => ['images', 'folders', currentBrandId.value]),
+  enabled: computed(() => Boolean(currentBrandId.value)),
   queryFn: () => imagesApi.listFolders(),
 })
 
@@ -59,6 +63,7 @@ const imagesQuery = useQuery({
   queryKey: computed(() => [
     'images',
     'list',
+    currentBrandId.value,
     {
       folder_id: debouncedSearch.value ? undefined : selectedFolderId.value,
       q: debouncedSearch.value,
@@ -66,6 +71,7 @@ const imagesQuery = useQuery({
       page_size: pageSize.value,
     },
   ]),
+  enabled: computed(() => Boolean(currentBrandId.value)),
   queryFn: () =>
     imagesApi.list({
       folder_id: debouncedSearch.value ? undefined : (selectedFolderId.value ?? undefined),
@@ -76,7 +82,8 @@ const imagesQuery = useQuery({
 })
 
 const allImagesCountQuery = useQuery({
-  queryKey: ['images', 'list', 'all-count'],
+  queryKey: computed(() => ['images', 'list', 'all-count', currentBrandId.value]),
+  enabled: computed(() => Boolean(currentBrandId.value)),
   queryFn: () =>
     imagesApi.list({
       page: 1,
@@ -181,6 +188,17 @@ watch(searchKeyword, () => {
   }, 300)
 })
 
+watch(currentBrandId, () => {
+  selectedFolderId.value = null
+  movingImage.value = null
+  previewingImage.value = null
+  renamingImage.value = null
+  moveModalOpen.value = false
+  previewModalOpen.value = false
+  renameImageModalOpen.value = false
+  currentPage.value = 1
+})
+
 function handleFolderSelect(id: number | null) {
   if (debouncedSearch.value) return
   selectedFolderId.value = id
diff --git a/apps/admin-web/src/views/KnowledgeView.vue b/apps/admin-web/src/views/KnowledgeView.vue
index 9aa44b6..4fd3385 100644
--- a/apps/admin-web/src/views/KnowledgeView.vue
+++ b/apps/admin-web/src/views/KnowledgeView.vue
@@ -16,6 +16,7 @@ import KnowledgeDetailDrawer from '@/components/KnowledgeDetailDrawer.vue'
 import { knowledgeApi } from '@/lib/api'
 import { formatDateTime } from '@/lib/display'
 import { formatError } from '@/lib/errors'
+import { useCompanyStore } from '@/stores/company'
 
 type KnowledgeSourceType = 'document' | 'website' | 'text'
 type KnowledgeGroupLevel = 'root' | 'child'
@@ -35,6 +36,8 @@ interface TreeNode {
 }
 
 const queryClient = useQueryClient()
+const companyStore = useCompanyStore()
+const currentBrandId = computed(() => companyStore.currentBrandId)
 
 const selectedGroupId = ref<number | null>(null)
 const groupModalOpen = ref(false)
@@ -59,12 +62,14 @@ const urlsText = ref('')
 const textItems = ref([{ name: '', content: '' }])
 
 const groupsQuery = useQuery({
-  queryKey: ['knowledge', 'groups'],
+  queryKey: computed(() => ['knowledge', 'groups', currentBrandId.value]),
+  enabled: computed(() => Boolean(currentBrandId.value)),
   queryFn: () => knowledgeApi.listGroups(),
 })
 
 const itemsQuery = useQuery({
-  queryKey: computed(() => ['knowledge', 'items', selectedGroupId.value]),
+  queryKey: computed(() => ['knowledge', 'items', currentBrandId.value, selectedGroupId.value]),
+  enabled: computed(() => Boolean(currentBrandId.value)),
   queryFn: () => knowledgeApi.listItems(selectedGroupId.value ?? undefined),
   refetchInterval: (query) => {
     const items = query.state.data as KnowledgeItem[] | undefined
@@ -267,6 +272,18 @@ const retryItemMutation = useMutation({
   onError: (error) => message.error(formatError(error)),
 })
 
+watch(
+  currentBrandId,
+  () => {
+    selectedGroupId.value = null
+    groupModalOpen.value = false
+    editingGroup.value = null
+    itemModalOpen.value = false
+    previewItemId.value = null
+    previewDrawerOpen.value = false
+  },
+)
+
 watch(
   () => groupsQuery.data.value,
   (groups) => {
diff --git a/server/internal/shared/retrieval/qdrant.go b/server/internal/shared/retrieval/qdrant.go
index ebb2d13..581a336 100644
--- a/server/internal/shared/retrieval/qdrant.go
+++ b/server/internal/shared/retrieval/qdrant.go
@@ -38,6 +38,7 @@ type VectorPoint struct {
 type SearchRequest struct {
 	Vector   []float64
 	TenantID int64
+	BrandID  int64
 	GroupIDs []int64
 	Limit    int
 }
@@ -193,6 +194,9 @@ func (s *qdrantStore) Search(ctx context.Context, req SearchRequest) ([]SearchPo
 			sdk.NewMatchKeyword("status", "active"),
 		},
 	}
+	if req.BrandID > 0 {
+		filter.Must = append(filter.Must, sdk.NewMatchInt("brand_id", req.BrandID))
+	}
 	groupIDs := normalizeGroupIDs(req.GroupIDs)
 	if len(groupIDs) > 0 {
 		filter.Must = append(filter.Must, sdk.NewMatchInts("group_id", groupIDs...))
diff --git a/server/internal/tenant/app/article_imitation_service.go b/server/internal/tenant/app/article_imitation_service.go
index 5c6c598..cd8e1b8 100644
--- a/server/internal/tenant/app/article_imitation_service.go
+++ b/server/internal/tenant/app/article_imitation_service.go
@@ -353,6 +353,7 @@ func (s *ArticleImitationService) executeGeneration(ctx context.Context, job art
 		knowledgeContext, resolveErr := s.knowledge.ResolveContext(
 			ctx,
 			job.TenantID,
+			int64(extractInt(job.InputParams, "brand_id")),
 			knowledgeGroupIDs,
 			buildImitationKnowledgeQuery(job.InputParams),
 		)
diff --git a/server/internal/tenant/app/article_service.go b/server/internal/tenant/app/article_service.go
index 4fa6a8c..699256d 100644
--- a/server/internal/tenant/app/article_service.go
+++ b/server/internal/tenant/app/article_service.go
@@ -492,6 +492,7 @@ func (s *ArticleService) loadArticleDetail(ctx context.Context, tenantID, brandI
 			ctx,
 			s.pool,
 			tenantID,
+			brandID,
 			markdownValue,
 			item.CoverImageAssetID,
 		)
@@ -628,6 +629,7 @@ func (s *ArticleService) Update(ctx context.Context, id int64, req UpdateArticle
 		ctx,
 		tx,
 		actor.TenantID,
+		brandID,
 		markdown,
 		coverImageAssetID,
 	)
@@ -1037,12 +1039,13 @@ func (s *ArticleService) resolveArticleImageMetadata(
 	ctx context.Context,
 	q imageAssetLookupQueryer,
 	tenantID int64,
+	brandID int64,
 	markdown string,
 	coverImageAssetID *int64,
 ) (string, []int64, *int64, error) {
 	referencedImageAssetIDs := extractReferencedImageAssetIDsFromMarkdown(markdown)
 	imageAssetIDsToValidate := collectImageAssetIDsForValidation(referencedImageAssetIDs, coverImageAssetID)
-	activeImageAssetIDs, err := s.loadActiveImageAssetIDSet(ctx, q, tenantID, imageAssetIDsToValidate)
+	activeImageAssetIDs, err := s.loadActiveImageAssetIDSet(ctx, q, tenantID, brandID, imageAssetIDsToValidate)
 	if err != nil {
 		return "", nil, nil, err
 	}
@@ -1064,6 +1067,7 @@ func (s *ArticleService) loadActiveImageAssetIDSet(
 	ctx context.Context,
 	q imageAssetLookupQueryer,
 	tenantID int64,
+	brandID int64,
 	imageAssetIDs []int64,
 ) (map[int64]struct{}, error) {
 	if len(imageAssetIDs) == 0 {
@@ -1073,11 +1077,12 @@ func (s *ArticleService) loadActiveImageAssetIDSet(
 	rows, err := q.Query(ctx, `
 SELECT id
 FROM image_assets
-WHERE tenant_id = $1
-  AND id = ANY($2::BIGINT[])
-  AND status = 'active'
-  AND deleted_at IS NULL
-`, tenantID, imageAssetIDs)
+	WHERE tenant_id = $1
+	  AND brand_id = $2
+	  AND id = ANY($3::BIGINT[])
+	  AND status = 'active'
+	  AND deleted_at IS NULL
+	`, tenantID, brandID, imageAssetIDs)
 	if err != nil {
 		return nil, response.ErrInternal(50012, "update_failed", "failed to validate image assets")
 	}
diff --git a/server/internal/tenant/app/enterprise_site_service.go b/server/internal/tenant/app/enterprise_site_service.go
index 70a1b06..3e8ee52 100644
--- a/server/internal/tenant/app/enterprise_site_service.go
+++ b/server/internal/tenant/app/enterprise_site_service.go
@@ -809,6 +809,7 @@ func (s *EnterpriseSiteService) PublishArticle(ctx context.Context, connectionID
 	contentHTML, coverURL := s.prepareEnterpriseSitePublishAssets(
 		ctx,
 		actor.TenantID,
+		brandID,
 		contentHTML,
 		coverURLInput,
 		coverImageAssetID,
@@ -1865,20 +1866,20 @@ func enterpriseSitePublishCoverInput(article enterpriseSitePublishArticle, req P
 	return coverURL, coverImageAssetID
 }
 
-func (s *EnterpriseSiteService) prepareEnterpriseSitePublishAssets(ctx context.Context, tenantID int64, contentHTML, coverURL string, coverImageAssetID *int64) (string, string) {
+func (s *EnterpriseSiteService) prepareEnterpriseSitePublishAssets(ctx context.Context, tenantID int64, brandID int64, contentHTML, coverURL string, coverImageAssetID *int64) (string, string) {
 	base := s.enterpriseSitePublicBaseURL()
-	preparedHTML := s.prepareEnterpriseSiteImageURLs(ctx, tenantID, contentHTML, base)
-	preparedCover := s.prepareEnterpriseSiteCoverURL(ctx, tenantID, coverURL, coverImageAssetID, base)
+	preparedHTML := s.prepareEnterpriseSiteImageURLs(ctx, tenantID, brandID, contentHTML, base)
+	preparedCover := s.prepareEnterpriseSiteCoverURL(ctx, tenantID, brandID, coverURL, coverImageAssetID, base)
 	return preparedHTML, preparedCover
 }
 
-func (s *EnterpriseSiteService) prepareEnterpriseSiteCoverURL(ctx context.Context, tenantID int64, coverURL string, coverImageAssetID *int64, baseURL string) string {
+func (s *EnterpriseSiteService) prepareEnterpriseSiteCoverURL(ctx context.Context, tenantID int64, brandID int64, coverURL string, coverImageAssetID *int64, baseURL string) string {
 	if coverImageAssetID != nil && *coverImageAssetID > 0 {
-		if dataURI := s.enterpriseSiteDataURIFromImageAssetID(ctx, tenantID, *coverImageAssetID); dataURI != "" {
+		if dataURI := s.enterpriseSiteDataURIFromImageAssetID(ctx, tenantID, brandID, *coverImageAssetID); dataURI != "" {
 			return dataURI
 		}
 	}
-	return s.prepareEnterpriseSiteAssetURL(ctx, tenantID, coverURL, baseURL)
+	return s.prepareEnterpriseSiteAssetURL(ctx, tenantID, brandID, coverURL, baseURL)
 }
 
 func (s *EnterpriseSiteService) enterpriseSitePublicBaseURL() string {
@@ -1918,7 +1919,7 @@ func normalizeEnterpriseSiteAssetBaseURL(value string) string {
 	return strings.TrimRight(parsed.String(), "/")
 }
 
-func (s *EnterpriseSiteService) prepareEnterpriseSiteImageURLs(ctx context.Context, tenantID int64, fragment string, baseURL string) string {
+func (s *EnterpriseSiteService) prepareEnterpriseSiteImageURLs(ctx context.Context, tenantID int64, brandID int64, fragment string, baseURL string) string {
 	if strings.TrimSpace(fragment) == "" || !strings.Contains(strings.ToLower(fragment), "<img") {
 		return fragment
 	}
@@ -1929,37 +1930,37 @@ func (s *EnterpriseSiteService) prepareEnterpriseSiteImageURLs(ctx context.Conte
 	}
 	nodes, err := html.ParseFragment(strings.NewReader(fragment), contextNode)
 	if err != nil {
-		return s.prepareEnterpriseSiteImageURLsFallback(ctx, tenantID, fragment, baseURL)
+		return s.prepareEnterpriseSiteImageURLsFallback(ctx, tenantID, brandID, fragment, baseURL)
 	}
 	for _, node := range nodes {
-		s.prepareEnterpriseSiteImageNodeURLs(ctx, tenantID, node, baseURL)
+		s.prepareEnterpriseSiteImageNodeURLs(ctx, tenantID, brandID, node, baseURL)
 	}
 	nodes = enterpriseSitePruneEmptyImageWrapperNodes(nodes)
-	return enterpriseSiteRenderHTMLNodes(nodes, s.prepareEnterpriseSiteImageURLsFallback(ctx, tenantID, fragment, baseURL))
+	return enterpriseSiteRenderHTMLNodes(nodes, s.prepareEnterpriseSiteImageURLsFallback(ctx, tenantID, brandID, fragment, baseURL))
 }
 
-func (s *EnterpriseSiteService) prepareEnterpriseSiteImageNodeURLs(ctx context.Context, tenantID int64, node *html.Node, baseURL string) {
+func (s *EnterpriseSiteService) prepareEnterpriseSiteImageNodeURLs(ctx context.Context, tenantID int64, brandID int64, node *html.Node, baseURL string) {
 	if node == nil {
 		return
 	}
 	if node.Type == html.ElementNode && strings.EqualFold(node.Data, "img") {
-		if !s.prepareEnterpriseSiteImageAttrs(ctx, tenantID, node, baseURL) {
+		if !s.prepareEnterpriseSiteImageAttrs(ctx, tenantID, brandID, node, baseURL) {
 			enterpriseSiteRemoveHTMLNode(node)
 			return
 		}
 	}
 	for child := node.FirstChild; child != nil; {
 		next := child.NextSibling
-		s.prepareEnterpriseSiteImageNodeURLs(ctx, tenantID, child, baseURL)
+		s.prepareEnterpriseSiteImageNodeURLs(ctx, tenantID, brandID, child, baseURL)
 		child = next
 	}
 }
 
-func (s *EnterpriseSiteService) prepareEnterpriseSiteImageAttrs(ctx context.Context, tenantID int64, node *html.Node, baseURL string) bool {
+func (s *EnterpriseSiteService) prepareEnterpriseSiteImageAttrs(ctx context.Context, tenantID int64, brandID int64, node *html.Node, baseURL string) bool {
 	if node == nil {
 		return true
 	}
-	dataURI := s.enterpriseSiteDataURIFromImageNode(ctx, tenantID, node)
+	dataURI := s.enterpriseSiteDataURIFromImageNode(ctx, tenantID, brandID, node)
 	hasImageURL := false
 	for idx := range node.Attr {
 		key := strings.ToLower(strings.TrimSpace(node.Attr[idx].Key))
@@ -1971,7 +1972,7 @@ func (s *EnterpriseSiteService) prepareEnterpriseSiteImageAttrs(ctx context.Cont
 			node.Attr[idx].Val = dataURI
 			continue
 		}
-		node.Attr[idx].Val = s.prepareEnterpriseSiteAssetURL(ctx, tenantID, node.Attr[idx].Val, baseURL)
+		node.Attr[idx].Val = s.prepareEnterpriseSiteAssetURL(ctx, tenantID, brandID, node.Attr[idx].Val, baseURL)
 		if strings.TrimSpace(node.Attr[idx].Val) == "" {
 			return false
 		}
@@ -2046,12 +2047,12 @@ func enterpriseSitePruneEmptyImageWrapperNodes(nodes []*html.Node) []*html.Node
 	return pruned
 }
 
-func (s *EnterpriseSiteService) prepareEnterpriseSiteAssetURL(ctx context.Context, tenantID int64, value string, baseURL string) string {
+func (s *EnterpriseSiteService) prepareEnterpriseSiteAssetURL(ctx context.Context, tenantID int64, brandID int64, value string, baseURL string) string {
 	value = strings.TrimSpace(value)
 	if value == "" || strings.HasPrefix(strings.ToLower(value), "data:") {
 		return value
 	}
-	if dataURI := s.enterpriseSiteDataURIFromAssetURL(ctx, tenantID, value); dataURI != "" {
+	if dataURI := s.enterpriseSiteDataURIFromAssetURL(ctx, tenantID, brandID, value); dataURI != "" {
 		return dataURI
 	}
 	if enterpriseSiteLooksLikeSaaSAssetURL(value) {
@@ -2060,34 +2061,34 @@ func (s *EnterpriseSiteService) prepareEnterpriseSiteAssetURL(ctx context.Contex
 	return enterpriseSiteAbsoluteAssetURL(value, baseURL)
 }
 
-func (s *EnterpriseSiteService) prepareEnterpriseSiteImageURLsFallback(ctx context.Context, tenantID int64, fragment string, baseURL string) string {
+func (s *EnterpriseSiteService) prepareEnterpriseSiteImageURLsFallback(ctx context.Context, tenantID int64, brandID int64, fragment string, baseURL string) string {
 	return enterpriseSiteImageAttrPattern.ReplaceAllStringFunc(fragment, func(match string) string {
 		parts := enterpriseSiteImageAttrPattern.FindStringSubmatch(match)
 		if len(parts) != 4 {
 			return match
 		}
-		return parts[1] + s.prepareEnterpriseSiteAssetURL(ctx, tenantID, parts[2], baseURL) + parts[3]
+		return parts[1] + s.prepareEnterpriseSiteAssetURL(ctx, tenantID, brandID, parts[2], baseURL) + parts[3]
 	})
 }
 
-func (s *EnterpriseSiteService) enterpriseSiteDataURIFromAssetURL(ctx context.Context, tenantID int64, value string) string {
-	objectKey, ok := s.enterpriseSiteObjectKeyFromAssetURL(ctx, tenantID, value)
+func (s *EnterpriseSiteService) enterpriseSiteDataURIFromAssetURL(ctx context.Context, tenantID int64, brandID int64, value string) string {
+	objectKey, ok := s.enterpriseSiteObjectKeyFromAssetURL(ctx, tenantID, brandID, value)
 	if !ok || s == nil || s.storage == nil {
 		return ""
 	}
 	return s.enterpriseSiteDataURIFromObjectKey(ctx, objectKey)
 }
 
-func (s *EnterpriseSiteService) enterpriseSiteDataURIFromImageNode(ctx context.Context, tenantID int64, node *html.Node) string {
+func (s *EnterpriseSiteService) enterpriseSiteDataURIFromImageNode(ctx context.Context, tenantID int64, brandID int64, node *html.Node) string {
 	assetID := enterpriseSiteImageNodeAssetID(node)
 	if assetID <= 0 {
 		return ""
 	}
-	return s.enterpriseSiteDataURIFromImageAssetID(ctx, tenantID, assetID)
+	return s.enterpriseSiteDataURIFromImageAssetID(ctx, tenantID, brandID, assetID)
 }
 
-func (s *EnterpriseSiteService) enterpriseSiteDataURIFromImageAssetID(ctx context.Context, tenantID, assetID int64) string {
-	objectKey, ok := s.loadEnterpriseSiteImageAssetObjectKey(ctx, tenantID, assetID)
+func (s *EnterpriseSiteService) enterpriseSiteDataURIFromImageAssetID(ctx context.Context, tenantID, brandID, assetID int64) string {
+	objectKey, ok := s.loadEnterpriseSiteImageAssetObjectKey(ctx, tenantID, brandID, assetID)
 	if !ok || s == nil || s.storage == nil {
 		return ""
 	}
@@ -2143,27 +2144,54 @@ func enterpriseSiteImageNodeAssetID(node *html.Node) int64 {
 	return 0
 }
 
-func (s *EnterpriseSiteService) enterpriseSiteObjectKeyFromAssetURL(ctx context.Context, tenantID int64, value string) (string, bool) {
+func (s *EnterpriseSiteService) enterpriseSiteObjectKeyFromAssetURL(ctx context.Context, tenantID int64, brandID int64, value string) (string, bool) {
 	if objectKey, ok := enterpriseSiteObjectKeyFromPublicAssetURL(value, tenantID, s.enterpriseSiteAssetTokenSecret()); ok {
+		if !s.enterpriseSiteImageObjectKeyBelongsToBrand(ctx, tenantID, brandID, objectKey) {
+			return "", false
+		}
 		return objectKey, true
 	}
 	assetID, ok := enterpriseSiteAssetIDFromURL(value)
 	if !ok {
 		return "", false
 	}
-	return s.loadEnterpriseSiteImageAssetObjectKey(ctx, tenantID, assetID)
+	return s.loadEnterpriseSiteImageAssetObjectKey(ctx, tenantID, brandID, assetID)
 }
 
-func (s *EnterpriseSiteService) loadEnterpriseSiteImageAssetObjectKey(ctx context.Context, tenantID, assetID int64) (string, bool) {
-	if s == nil || s.pool == nil || tenantID <= 0 || assetID <= 0 {
+func (s *EnterpriseSiteService) enterpriseSiteImageObjectKeyBelongsToBrand(ctx context.Context, tenantID, brandID int64, objectKey string) bool {
+	if s == nil || s.pool == nil || !enterpriseSiteObjectKeyIsImageLibraryAsset(objectKey, tenantID) {
+		return true
+	}
+	if tenantID <= 0 || brandID <= 0 || strings.TrimSpace(objectKey) == "" {
+		return false
+	}
+	var exists bool
+	if err := s.pool.QueryRow(ctx, `
+			SELECT EXISTS (
+				SELECT 1
+				FROM image_assets
+				WHERE tenant_id = $1
+				  AND brand_id = $2
+				  AND object_key = $3
+				  AND status = 'active'
+				  AND deleted_at IS NULL
+			)
+		`, tenantID, brandID, objectKey).Scan(&exists); err != nil {
+		return false
+	}
+	return exists
+}
+
+func (s *EnterpriseSiteService) loadEnterpriseSiteImageAssetObjectKey(ctx context.Context, tenantID, brandID, assetID int64) (string, bool) {
+	if s == nil || s.pool == nil || tenantID <= 0 || brandID <= 0 || assetID <= 0 {
 		return "", false
 	}
 	var objectKey string
 	if err := s.pool.QueryRow(ctx, `
-		SELECT object_key
-		FROM image_assets
-		WHERE id = $1 AND tenant_id = $2 AND status = 'active' AND deleted_at IS NULL
-	`, assetID, tenantID).Scan(&objectKey); err != nil {
+			SELECT object_key
+			FROM image_assets
+			WHERE id = $1 AND tenant_id = $2 AND brand_id = $3 AND status = 'active' AND deleted_at IS NULL
+		`, assetID, tenantID, brandID).Scan(&objectKey); err != nil {
 		return "", false
 	}
 	if !enterpriseSiteObjectKeyAllowedForTenant(objectKey, tenantID) {
@@ -2264,6 +2292,14 @@ func enterpriseSiteObjectKeyAllowedForTenant(objectKey string, tenantID int64) b
 		strings.HasPrefix(objectKey, tenantPrefix+"articles/")
 }
 
+func enterpriseSiteObjectKeyIsImageLibraryAsset(objectKey string, tenantID int64) bool {
+	if tenantID <= 0 {
+		return false
+	}
+	tenantPrefix := "tenants/" + strconv.FormatInt(tenantID, 10) + "/"
+	return strings.HasPrefix(strings.TrimSpace(objectKey), tenantPrefix+"images/")
+}
+
 func enterpriseSiteAbsoluteImageURLs(fragment string, baseURL string) string {
 	if strings.TrimSpace(fragment) == "" || !strings.Contains(strings.ToLower(fragment), "<img") {
 		return fragment
diff --git a/server/internal/tenant/app/enterprise_site_service_test.go b/server/internal/tenant/app/enterprise_site_service_test.go
index f00758d..f919e9b 100644
--- a/server/internal/tenant/app/enterprise_site_service_test.go
+++ b/server/internal/tenant/app/enterprise_site_service_test.go
@@ -245,6 +245,7 @@ func TestPrepareEnterpriseSiteImageURLsEmbedsPublicAssetImages(t *testing.T) {
 	got := svc.prepareEnterpriseSiteImageURLs(
 		context.Background(),
 		7,
+		11,
 		`<p><img src="/api/public/assets/`+token+`" data-src="/api/public/assets/`+token+`" /></p>`,
 		"http://127.0.0.1:8080",
 	)
@@ -271,6 +272,7 @@ func TestPrepareEnterpriseSiteImageURLsEmbedsPublicAssetImagesWithStaleSignature
 	got := svc.prepareEnterpriseSiteImageURLs(
 		context.Background(),
 		7,
+		11,
 		`<p><img src="http://localhost:5178/api/public/assets/`+token+`" /></p>`,
 		"http://127.0.0.1:8080",
 	)
@@ -297,6 +299,7 @@ func TestPrepareEnterpriseSiteImageURLsStripsSaaSImageAttrs(t *testing.T) {
 	got := svc.prepareEnterpriseSiteImageURLs(
 		context.Background(),
 		7,
+		11,
 		`<p><img src="/api/public/assets/`+token+`" alt="" data-asset-id="35" asset-id="35" /></p>`,
 		"http://127.0.0.1:8080",
 	)
@@ -320,6 +323,7 @@ func TestPrepareEnterpriseSiteImageURLsDropsUnavailableSaaSAssetImage(t *testing
 	got := svc.prepareEnterpriseSiteImageURLs(
 		context.Background(),
 		7,
+		11,
 		`<p>前文</p><p class="article-editor-image article-editor-image--center" align="center"><img src="http://localhost:5178/api/public/assets/`+token+`" alt="" /></p><p>后文</p>`,
 		"http://127.0.0.1:8080",
 	)
@@ -346,6 +350,7 @@ func TestPrepareEnterpriseSiteImageURLsEmbedsIncompletePublicAssetPaths(t *testi
 	got := svc.prepareEnterpriseSiteImageURLs(
 		context.Background(),
 		7,
+		11,
 		`<p><img src="api/public/assets/`+token+`?format=png" /></p>`,
 		"http://127.0.0.1:8080",
 	)
@@ -373,7 +378,7 @@ func TestMarkdownRenderedEnterpriseSiteImageEmbedsIncompletePublicAssetPath(t *t
 		t.Fatalf("render markdown: %v", err)
 	}
 
-	got := svc.prepareEnterpriseSiteImageURLs(context.Background(), 7, html, "http://127.0.0.1:8080")
+	got := svc.prepareEnterpriseSiteImageURLs(context.Background(), 7, 11, html, "http://127.0.0.1:8080")
 
 	if storage.gotKey != objectKey {
 		t.Fatalf("object key = %q, want %q", storage.gotKey, objectKey)
@@ -398,6 +403,7 @@ func TestPrepareEnterpriseSitePublishAssetsEmbedsIncompleteCoverAssetPath(t *tes
 	got := svc.prepareEnterpriseSiteCoverURL(
 		context.Background(),
 		7,
+		11,
 		"api/public/assets/"+token+"?format=png",
 		nil,
 		"http://127.0.0.1:8080",
@@ -423,6 +429,7 @@ func TestPrepareEnterpriseSiteCoverURLDropsUnavailableSaaSAssetURL(t *testing.T)
 	got := svc.prepareEnterpriseSiteCoverURL(
 		context.Background(),
 		7,
+		11,
 		"http://localhost:5178/api/public/assets/"+token,
 		nil,
 		"http://127.0.0.1:8080",
diff --git a/server/internal/tenant/app/generation_task_runtime.go b/server/internal/tenant/app/generation_task_runtime.go
index e428623..0c7c8e2 100644
--- a/server/internal/tenant/app/generation_task_runtime.go
+++ b/server/internal/tenant/app/generation_task_runtime.go
@@ -376,6 +376,7 @@ func (s *PromptRuleGenerationService) ProcessQueuedTask(ctx context.Context, tas
 			knowledgeContext, err := s.knowledge.ResolveContext(
 				ctx,
 				task.TenantID,
+				int64(extractInt(inputParams, "brand_id")),
 				knowledgeGroupIDs,
 				buildPromptRuleKnowledgeQuery(rule, inputParams),
 			)
diff --git a/server/internal/tenant/app/image_folder_service.go b/server/internal/tenant/app/image_folder_service.go
index efd0116..64aea34 100644
--- a/server/internal/tenant/app/image_folder_service.go
+++ b/server/internal/tenant/app/image_folder_service.go
@@ -10,6 +10,7 @@ import (
 	"github.com/jackc/pgx/v5/pgxpool"
 	"go.uber.org/zap"
 
+	"github.com/geo-platform/tenant-api/internal/shared/auth"
 	"github.com/geo-platform/tenant-api/internal/shared/messaging/rabbitmq"
 	"github.com/geo-platform/tenant-api/internal/shared/middleware"
 	"github.com/geo-platform/tenant-api/internal/shared/objectstorage"
@@ -48,9 +49,13 @@ type ImageReferenceArticleBrief struct {
 
 func (s *ImageFolderService) List(ctx context.Context) ([]ImageFolderItem, error) {
 	tenantID := middleware.TenantIDFromCtx(ctx)
+	brandID, err := requireCurrentBrandID(ctx)
+	if err != nil {
+		return nil, err
+	}
 	repo := repository.NewImageFolderRepository(s.pool)
 
-	folders, err := repo.List(ctx, tenantID)
+	folders, err := repo.List(ctx, tenantID, brandID)
 	if err != nil {
 		return nil, err
 	}
@@ -77,11 +82,15 @@ func (s *ImageFolderService) Create(ctx context.Context, name string) (int64, er
 	}
 
 	tenantID := middleware.TenantIDFromCtx(ctx)
+	brandID, err := requireCurrentBrandID(ctx)
+	if err != nil {
+		return 0, err
+	}
 	repo := repository.NewImageFolderRepository(s.pool)
 
-	id, err := repo.Create(ctx, tenantID, name)
+	id, err := repo.Create(ctx, tenantID, brandID, name)
 	if err != nil {
-		if isConstraintError(err, "uq_image_folders_tenant_name") {
+		if isConstraintError(err, "uq_image_folders_tenant_name") || isConstraintError(err, "uq_image_folders_tenant_brand_name") {
 			return 0, response.ErrConflict(40901, "folder_name_exists", "a folder with this name already exists")
 		}
 		return 0, err
@@ -96,13 +105,17 @@ func (s *ImageFolderService) Update(ctx context.Context, id int64, name string)
 	}
 
 	tenantID := middleware.TenantIDFromCtx(ctx)
+	brandID, err := requireCurrentBrandID(ctx)
+	if err != nil {
+		return err
+	}
 	repo := repository.NewImageFolderRepository(s.pool)
-	if _, err := repo.Get(ctx, tenantID, id); err != nil {
+	if _, err := repo.Get(ctx, tenantID, brandID, id); err != nil {
 		return mapImageFolderNotFound(err)
 	}
 
-	if err := repo.Update(ctx, tenantID, id, name); err != nil {
-		if isConstraintError(err, "uq_image_folders_tenant_name") {
+	if err := repo.Update(ctx, tenantID, brandID, id, name); err != nil {
+		if isConstraintError(err, "uq_image_folders_tenant_name") || isConstraintError(err, "uq_image_folders_tenant_brand_name") {
 			return response.ErrConflict(40901, "folder_name_exists", "a folder with this name already exists")
 		}
 		return err
@@ -112,13 +125,17 @@ func (s *ImageFolderService) Update(ctx context.Context, id int64, name string)
 
 func (s *ImageFolderService) DeletePreview(ctx context.Context, folderID int64) (*FolderDeletePreview, error) {
 	tenantID := middleware.TenantIDFromCtx(ctx)
+	brandID, err := requireCurrentBrandID(ctx)
+	if err != nil {
+		return nil, err
+	}
 	folderRepo := repository.NewImageFolderRepository(s.pool)
 
-	if _, err := folderRepo.Get(ctx, tenantID, folderID); err != nil {
+	if _, err := folderRepo.Get(ctx, tenantID, brandID, folderID); err != nil {
 		return nil, mapImageFolderNotFound(err)
 	}
 
-	imageCount, err := folderRepo.CountActiveImages(ctx, tenantID, folderID)
+	imageCount, err := folderRepo.CountActiveImages(ctx, tenantID, brandID, folderID)
 	if err != nil {
 		return nil, err
 	}
@@ -131,19 +148,23 @@ func (s *ImageFolderService) DeletePreview(ctx context.Context, folderID int64)
 
 func (s *ImageFolderService) Delete(ctx context.Context, folderID int64, force bool) error {
 	tenantID := middleware.TenantIDFromCtx(ctx)
+	brandID, err := requireCurrentBrandID(ctx)
+	if err != nil {
+		return err
+	}
 	folderRepo := repository.NewImageFolderRepository(s.pool)
 	imageRepo := repository.NewImageRepository(s.pool)
 
-	if _, err := folderRepo.Get(ctx, tenantID, folderID); err != nil {
+	if _, err := folderRepo.Get(ctx, tenantID, brandID, folderID); err != nil {
 		return mapImageFolderNotFound(err)
 	}
 
-	imageCount, err := folderRepo.CountActiveImages(ctx, tenantID, folderID)
+	imageCount, err := folderRepo.CountActiveImages(ctx, tenantID, brandID, folderID)
 	if err != nil {
 		return err
 	}
 	if imageCount == 0 {
-		return folderRepo.Delete(ctx, tenantID, folderID)
+		return folderRepo.Delete(ctx, tenantID, brandID, folderID)
 	}
 
 	if !force {
@@ -159,7 +180,7 @@ func (s *ImageFolderService) Delete(ctx context.Context, folderID int64, force b
 		}
 	}
 
-	images, err := imageRepo.ListActiveByFolder(ctx, tenantID, folderID)
+	images, err := imageRepo.ListActiveByFolder(ctx, tenantID, brandID, folderID)
 	if err != nil {
 		return err
 	}
@@ -174,10 +195,10 @@ func (s *ImageFolderService) Delete(ctx context.Context, folderID int64, force b
 
 	imageRepoTx := repository.NewImageRepository(tx)
 	folderRepoTx := repository.NewImageFolderRepository(tx)
-	if err := imageRepoTx.MarkImagesInFolderPendingDelete(ctx, tenantID, folderID); err != nil {
+	if err := imageRepoTx.MarkImagesInFolderPendingDelete(ctx, tenantID, brandID, folderID); err != nil {
 		return response.ErrInternal(50048, "folder_image_delete_prepare_failed", "failed to prepare folder images for deletion")
 	}
-	if err := folderRepoTx.Delete(ctx, tenantID, folderID); err != nil {
+	if err := folderRepoTx.Delete(ctx, tenantID, brandID, folderID); err != nil {
 		return err
 	}
 	if err := tx.Commit(ctx); err != nil {
@@ -185,7 +206,8 @@ func (s *ImageFolderService) Delete(ctx context.Context, folderID int64, force b
 	}
 
 	for _, image := range images {
-		if err := s.imageSvc.finalizeDeleteNowOrEnqueue(ctx, tenantID, image.ID); err != nil {
+		deleteCtx := auth.WithCurrentBrandID(ctx, brandID)
+		if err := s.imageSvc.finalizeDeleteNowOrEnqueue(deleteCtx, tenantID, image.ID); err != nil {
 			return err
 		}
 	}
diff --git a/server/internal/tenant/app/image_service.go b/server/internal/tenant/app/image_service.go
index 99b2d29..27c74bd 100644
--- a/server/internal/tenant/app/image_service.go
+++ b/server/internal/tenant/app/image_service.go
@@ -158,9 +158,13 @@ func (s *ImageService) Upload(ctx context.Context, fileName string, content []by
 	}
 
 	tenantID := middleware.TenantIDFromCtx(ctx)
+	brandID, err := requireCurrentBrandID(ctx)
+	if err != nil {
+		return nil, err
+	}
 	actor := auth.MustActor(ctx)
 	if folderID != nil {
-		if err := s.ensureFolderExists(ctx, tenantID, *folderID); err != nil {
+		if err := s.ensureFolderExists(ctx, tenantID, brandID, *folderID); err != nil {
 			return nil, err
 		}
 	}
@@ -181,7 +185,7 @@ func (s *ImageService) Upload(ctx context.Context, fileName string, content []by
 
 	sizeBytes := int64(len(webpBytes))
 	contentHash := hashImageContent(webpBytes)
-	existingAsset, err := s.findActiveImageAssetByContentHash(ctx, tenantID, contentHash)
+	existingAsset, err := s.findActiveImageAssetByContentHash(ctx, tenantID, brandID, contentHash)
 	if err != nil {
 		return nil, response.ErrInternal(50012, "image_asset_lookup_failed", "failed to check existing image asset")
 	}
@@ -219,9 +223,9 @@ func (s *ImageService) Upload(ctx context.Context, fileName string, content []by
 		return nil, response.ErrInternal(50015, "image_quota_reserve_failed", "failed to reserve image storage quota")
 	}
 
-	assetID, err := s.insertPendingImageAsset(ctx, tx, tenantID, folderID, objectKey, displayName, sizeBytes, contentHash, actor.UserID)
+	assetID, err := s.insertPendingImageAsset(ctx, tx, tenantID, brandID, folderID, objectKey, displayName, sizeBytes, contentHash, actor.UserID)
 	if err != nil {
-		if isConstraintError(err, "fk_image_assets_folder") {
+		if isConstraintError(err, "fk_image_assets_folder") || isConstraintError(err, "fk_image_assets_folder_brand") {
 			return nil, response.ErrNotFound(40402, "image_folder_not_found", "folder not found")
 		}
 		return nil, response.ErrInternal(50016, "image_asset_create_failed", "failed to create image asset")
@@ -241,7 +245,7 @@ func (s *ImageService) Upload(ctx context.Context, fileName string, content []by
 	}
 
 	imageRepo := repository.NewImageRepository(s.pool)
-	if err := imageRepo.UpdateStatus(ctx, tenantID, assetID, "active"); err != nil {
+	if err := imageRepo.UpdateStatus(ctx, tenantID, brandID, assetID, "active"); err != nil {
 		s.logError("failed to mark image active after upload", zap.Int64("tenant_id", tenantID), zap.Int64("asset_id", assetID), zap.Error(err))
 		if queueErr := s.enqueueFinalizeUploadTask(tenantID, assetID); queueErr == nil {
 			return &ImageUploadResult{
@@ -282,9 +286,14 @@ func (s *ImageService) List(ctx context.Context, folderID *int64, query *string,
 	}
 
 	tenantID := middleware.TenantIDFromCtx(ctx)
+	brandID, err := requireCurrentBrandID(ctx)
+	if err != nil {
+		return nil, err
+	}
 	repo := repository.NewImageRepository(s.pool)
 	assets, total, err := repo.List(ctx, repository.ImageAssetListParams{
 		TenantID:    tenantID,
+		BrandID:     brandID,
 		FolderID:    folderID,
 		SearchQuery: searchQuery,
 		PageSize:    pageSize,
@@ -323,9 +332,13 @@ func (s *ImageService) Update(ctx context.Context, id int64, req ImageUpdateRequ
 	}
 
 	tenantID := middleware.TenantIDFromCtx(ctx)
+	brandID, err := requireCurrentBrandID(ctx)
+	if err != nil {
+		return err
+	}
 	repo := repository.NewImageRepository(s.pool)
 
-	asset, err := repo.Get(ctx, tenantID, id)
+	asset, err := repo.Get(ctx, tenantID, brandID, id)
 	if err != nil {
 		return mapImageNotFound(err)
 	}
@@ -341,7 +354,7 @@ func (s *ImageService) Update(ctx context.Context, id int64, req ImageUpdateRequ
 		if len(name) > 255 {
 			return response.ErrBadRequest(40002, "invalid_name", "name must be at most 255 characters")
 		}
-		if err := repo.UpdateName(ctx, tenantID, id, name); err != nil {
+		if err := repo.UpdateName(ctx, tenantID, brandID, id, name); err != nil {
 			return err
 		}
 	}
@@ -352,12 +365,12 @@ func (s *ImageService) Update(ctx context.Context, id int64, req ImageUpdateRequ
 			return err
 		}
 		if folderID != nil {
-			if err := s.ensureFolderExists(ctx, tenantID, *folderID); err != nil {
+			if err := s.ensureFolderExists(ctx, tenantID, brandID, *folderID); err != nil {
 				return err
 			}
 		}
-		if err := repo.UpdateFolder(ctx, tenantID, id, folderID); err != nil {
-			if isConstraintError(err, "fk_image_assets_folder") {
+		if err := repo.UpdateFolder(ctx, tenantID, brandID, id, folderID); err != nil {
+			if isConstraintError(err, "fk_image_assets_folder") || isConstraintError(err, "fk_image_assets_folder_brand") {
 				return response.ErrNotFound(40402, "image_folder_not_found", "folder not found")
 			}
 			return err
@@ -374,7 +387,7 @@ type existingImageAsset struct {
 	SizeBytes int64
 }
 
-func (s *ImageService) findActiveImageAssetByContentHash(ctx context.Context, tenantID int64, contentHash string) (*existingImageAsset, error) {
+func (s *ImageService) findActiveImageAssetByContentHash(ctx context.Context, tenantID, brandID int64, contentHash string) (*existingImageAsset, error) {
 	if strings.TrimSpace(contentHash) == "" {
 		return nil, nil
 	}
@@ -384,12 +397,13 @@ func (s *ImageService) findActiveImageAssetByContentHash(ctx context.Context, te
 SELECT id, object_key, name, size_bytes
 FROM image_assets
 WHERE tenant_id = $1
-  AND content_hash = $2
+  AND brand_id = $2
+  AND content_hash = $3
   AND status = 'active'
   AND deleted_at IS NULL
 ORDER BY created_at DESC
 LIMIT 1
-`, tenantID, contentHash).Scan(&asset.ID, &asset.ObjectKey, &asset.Name, &asset.SizeBytes)
+`, tenantID, brandID, contentHash).Scan(&asset.ID, &asset.ObjectKey, &asset.Name, &asset.SizeBytes)
 	if err != nil {
 		if errors.Is(err, pgx.ErrNoRows) {
 			return nil, nil
@@ -404,6 +418,7 @@ func (s *ImageService) insertPendingImageAsset(
 	ctx context.Context,
 	tx pgx.Tx,
 	tenantID int64,
+	brandID int64,
 	folderID *int64,
 	objectKey string,
 	name string,
@@ -412,10 +427,10 @@ func (s *ImageService) insertPendingImageAsset(
 	createdBy int64,
 ) (int64, error) {
 	row := tx.QueryRow(ctx, `
-INSERT INTO image_assets (tenant_id, folder_id, object_key, name, size_bytes, status, content_hash, created_by)
-VALUES ($1, $2, $3, $4, $5, 'pending_upload', $6, $7)
+INSERT INTO image_assets (tenant_id, brand_id, folder_id, object_key, name, size_bytes, status, content_hash, created_by)
+VALUES ($1, $2, $3, $4, $5, $6, 'pending_upload', $7, $8)
 RETURNING id
-`, tenantID, nullableImageFolderValue(folderID), objectKey, name, sizeBytes, contentHash, createdBy)
+`, tenantID, brandID, nullableImageFolderValue(folderID), objectKey, name, sizeBytes, contentHash, createdBy)
 
 	var assetID int64
 	if err := row.Scan(&assetID); err != nil {
@@ -426,10 +441,14 @@ RETURNING id
 
 func (s *ImageService) GetReferences(ctx context.Context, imageID int64) (*ImageReferenceDetail, error) {
 	tenantID := middleware.TenantIDFromCtx(ctx)
+	brandID, err := requireCurrentBrandID(ctx)
+	if err != nil {
+		return nil, err
+	}
 	imageRepo := repository.NewImageRepository(s.pool)
 	refRepo := repository.NewImageReferenceRepository(s.pool)
 
-	asset, err := imageRepo.Get(ctx, tenantID, imageID)
+	asset, err := imageRepo.Get(ctx, tenantID, brandID, imageID)
 	if err != nil {
 		return nil, mapImageNotFound(err)
 	}
@@ -494,10 +513,14 @@ func (s *ImageService) Delete(ctx context.Context, id int64, force bool) error {
 	}
 
 	tenantID := middleware.TenantIDFromCtx(ctx)
+	brandID, err := requireCurrentBrandID(ctx)
+	if err != nil {
+		return err
+	}
 	imageRepo := repository.NewImageRepository(s.pool)
 	refRepo := repository.NewImageReferenceRepository(s.pool)
 
-	asset, err := imageRepo.Get(ctx, tenantID, id)
+	asset, err := imageRepo.Get(ctx, tenantID, brandID, id)
 	if err != nil {
 		return mapImageNotFound(err)
 	}
@@ -515,7 +538,7 @@ func (s *ImageService) Delete(ctx context.Context, id int64, force bool) error {
 		}
 	}
 
-	if err := imageRepo.UpdateStatus(ctx, tenantID, id, "pending_delete"); err != nil {
+	if err := imageRepo.UpdateStatus(ctx, tenantID, brandID, id, "pending_delete"); err != nil {
 		return err
 	}
 
@@ -556,7 +579,13 @@ func (s *ImageService) rollbackUpload(ctx context.Context, tenantID, assetID, si
 	imageRepo := repository.NewImageRepository(s.pool)
 	usageRepo := repository.NewImageUsageRepository(s.pool)
 
-	if err := imageRepo.UpdateStatus(ctx, tenantID, assetID, "upload_failed"); err != nil {
+	brandID, err := s.lookupImageAssetBrandID(ctx, tenantID, assetID)
+	if err != nil {
+		s.logError("failed to resolve image brand after upload rollback", zap.Int64("tenant_id", tenantID), zap.Int64("asset_id", assetID), zap.Error(err))
+		return
+	}
+
+	if err := imageRepo.UpdateStatus(ctx, tenantID, brandID, assetID, "upload_failed"); err != nil {
 		s.logError("failed to mark image upload as failed", zap.Int64("tenant_id", tenantID), zap.Int64("asset_id", assetID), zap.Error(err))
 	}
 	if err := usageRepo.Release(ctx, tenantID, sizeBytes); err != nil {
@@ -605,11 +634,11 @@ func (s *ImageService) ProcessFinalizeUpload(ctx context.Context, tenantID, asse
 
 	imageRepoTx := repository.NewImageRepository(tx)
 	if exists {
-		if err := imageRepoTx.UpdateStatus(ctx, tenantID, assetID, "active"); err != nil {
+		if err := imageRepoTx.UpdateStatus(ctx, tenantID, lockedAsset.BrandID, assetID, "active"); err != nil {
 			return response.ErrInternal(50033, "image_upload_finalize_failed", "failed to activate uploaded image")
 		}
 	} else {
-		if err := imageRepoTx.UpdateStatus(ctx, tenantID, assetID, "upload_failed"); err != nil {
+		if err := imageRepoTx.UpdateStatus(ctx, tenantID, lockedAsset.BrandID, assetID, "upload_failed"); err != nil {
 			return response.ErrInternal(50034, "image_upload_finalize_failed", "failed to mark image upload as failed")
 		}
 		usageRepoTx := repository.NewImageUsageRepository(tx)
@@ -680,7 +709,7 @@ WHERE tenant_id = $1 AND image_asset_id = $2
 
 	imageRepoTx := repository.NewImageRepository(tx)
 	usageRepoTx := repository.NewImageUsageRepository(tx)
-	if err := imageRepoTx.MarkDeleted(ctx, tenantID, assetID); err != nil {
+	if err := imageRepoTx.MarkDeleted(ctx, tenantID, lockedAsset.BrandID, assetID); err != nil {
 		return response.ErrInternal(50044, "image_delete_finalize_failed", "failed to finalize image deletion")
 	}
 	if err := usageRepoTx.Release(ctx, tenantID, lockedAsset.SizeBytes); err != nil {
@@ -725,10 +754,15 @@ func (s *ImageService) enqueueFinalizeDeleteTask(tenantID, assetID int64) error
 }
 
 func (s *ImageService) loadImageAsset(ctx context.Context, tenantID, assetID int64) (*repository.ImageAsset, error) {
-	return repository.NewImageRepository(s.pool).Get(ctx, tenantID, assetID)
+	brandID, err := s.lookupImageAssetBrandID(ctx, tenantID, assetID)
+	if err != nil {
+		return nil, err
+	}
+	return repository.NewImageRepository(s.pool).Get(ctx, tenantID, brandID, assetID)
 }
 
 type lockedImageAsset struct {
+	BrandID   int64
 	ObjectKey string
 	SizeBytes int64
 	Status    string
@@ -739,11 +773,11 @@ func (s *ImageService) lockImageAsset(ctx context.Context, tx pgx.Tx, tenantID,
 	var asset lockedImageAsset
 	var deletedAt *time.Time
 	err := tx.QueryRow(ctx, `
-SELECT object_key, size_bytes, status, deleted_at
+SELECT brand_id, object_key, size_bytes, status, deleted_at
 FROM image_assets
 WHERE tenant_id = $1 AND id = $2
 FOR UPDATE
-`, tenantID, assetID).Scan(&asset.ObjectKey, &asset.SizeBytes, &asset.Status, &deletedAt)
+`, tenantID, assetID).Scan(&asset.BrandID, &asset.ObjectKey, &asset.SizeBytes, &asset.Status, &deletedAt)
 	if err != nil {
 		if errors.Is(err, pgx.ErrNoRows) {
 			return nil, false, nil
@@ -754,14 +788,26 @@ FOR UPDATE
 	return &asset, true, nil
 }
 
-func (s *ImageService) ensureFolderExists(ctx context.Context, tenantID, folderID int64) error {
+func (s *ImageService) ensureFolderExists(ctx context.Context, tenantID, brandID, folderID int64) error {
 	folderRepo := repository.NewImageFolderRepository(s.pool)
-	if _, err := folderRepo.Get(ctx, tenantID, folderID); err != nil {
+	if _, err := folderRepo.Get(ctx, tenantID, brandID, folderID); err != nil {
 		return mapImageFolderNotFound(err)
 	}
 	return nil
 }
 
+func (s *ImageService) lookupImageAssetBrandID(ctx context.Context, tenantID, assetID int64) (int64, error) {
+	var brandID int64
+	if err := s.pool.QueryRow(ctx, `
+SELECT brand_id
+FROM image_assets
+WHERE tenant_id = $1 AND id = $2
+`, tenantID, assetID).Scan(&brandID); err != nil {
+		return 0, err
+	}
+	return brandID, nil
+}
+
 func (s *ImageService) lookupImageQuotaBytes(ctx context.Context, tenantID int64) (int64, error) {
 	var quotaBytes int64
 	err := s.pool.QueryRow(ctx, `
diff --git a/server/internal/tenant/app/knowledge_service.go b/server/internal/tenant/app/knowledge_service.go
index d485815..68cb172 100644
--- a/server/internal/tenant/app/knowledge_service.go
+++ b/server/internal/tenant/app/knowledge_service.go
@@ -61,6 +61,7 @@ type knowledgeParseJob struct {
 type knowledgeItemRecord struct {
 	ID          int64
 	TenantID    int64
+	BrandID     int64
 	GroupID     int64
 	GroupName   string
 	Name        string
@@ -207,12 +208,16 @@ func (s *KnowledgeService) runtimeConfig() knowledgeRuntimeConfig {
 
 func (s *KnowledgeService) ListGroups(ctx context.Context) ([]KnowledgeGroupResponse, error) {
 	actor := auth.MustActor(ctx)
+	brandID, err := requireCurrentBrandID(ctx)
+	if err != nil {
+		return nil, err
+	}
 	rows, err := s.pool.Query(ctx, `
 		SELECT id, name, parent_id, sort_order, created_at
 		FROM knowledge_groups
-		WHERE tenant_id = $1 AND deleted_at IS NULL
+		WHERE tenant_id = $1 AND brand_id = $2 AND deleted_at IS NULL
 		ORDER BY sort_order, created_at, id
-	`, actor.TenantID)
+	`, actor.TenantID, brandID)
 	if err != nil {
 		return nil, response.ErrInternal(50050, "knowledge_groups_query_failed", "failed to list knowledge groups")
 	}
@@ -240,6 +245,7 @@ func (s *KnowledgeService) ListGroups(ctx context.Context) ([]KnowledgeGroupResp
 		SELECT ki.group_id, COUNT(DISTINCT ki.id)::bigint
 		FROM knowledge_items ki
 		WHERE ki.tenant_id = $1
+		  AND ki.brand_id = $2
 		  AND ki.deleted_at IS NULL
 		  AND ki.status = 'completed'
 		  AND EXISTS (
@@ -251,7 +257,7 @@ func (s *KnowledgeService) ListGroups(ctx context.Context) ([]KnowledgeGroupResp
 			    AND kcm.status = 'active'
 		  )
 		GROUP BY ki.group_id
-	`, actor.TenantID)
+	`, actor.TenantID, brandID)
 	if err != nil {
 		return nil, response.ErrInternal(50050, "knowledge_group_counts_query_failed", "failed to list knowledge group counts")
 	}
@@ -310,6 +316,10 @@ func (s *KnowledgeService) ListGroups(ctx context.Context) ([]KnowledgeGroupResp
 
 func (s *KnowledgeService) CreateGroup(ctx context.Context, req KnowledgeGroupRequest) (*KnowledgeGroupResponse, error) {
 	actor := auth.MustActor(ctx)
+	brandID, err := requireCurrentBrandID(ctx)
+	if err != nil {
+		return nil, err
+	}
 
 	name := strings.TrimSpace(req.Name)
 	if name == "" {
@@ -318,7 +328,7 @@ func (s *KnowledgeService) CreateGroup(ctx context.Context, req KnowledgeGroupRe
 
 	var parentID *int64
 	if req.ParentID != nil && *req.ParentID > 0 {
-		if err := s.ensureRootGroup(ctx, actor.TenantID, *req.ParentID); err != nil {
+		if err := s.ensureRootGroup(ctx, actor.TenantID, brandID, *req.ParentID); err != nil {
 			return nil, err
 		}
 		parentID = req.ParentID
@@ -333,11 +343,11 @@ func (s *KnowledgeService) CreateGroup(ctx context.Context, req KnowledgeGroupRe
 		groupID   int64
 		createdAt time.Time
 	)
-	err := s.pool.QueryRow(ctx, `
-		INSERT INTO knowledge_groups (tenant_id, name, parent_id, sort_order)
-		VALUES ($1, $2, $3, $4)
+	err = s.pool.QueryRow(ctx, `
+		INSERT INTO knowledge_groups (tenant_id, brand_id, name, parent_id, sort_order)
+		VALUES ($1, $2, $3, $4, $5)
 		RETURNING id, created_at
-	`, actor.TenantID, name, parentID, sortOrder).Scan(&groupID, &createdAt)
+	`, actor.TenantID, brandID, name, parentID, sortOrder).Scan(&groupID, &createdAt)
 	if err != nil {
 		return nil, response.ErrConflict(40950, "knowledge_group_create_failed", "knowledge group already exists or cannot be created")
 	}
@@ -355,6 +365,10 @@ func (s *KnowledgeService) CreateGroup(ctx context.Context, req KnowledgeGroupRe
 
 func (s *KnowledgeService) UpdateGroup(ctx context.Context, groupID int64, req KnowledgeGroupRequest) error {
 	actor := auth.MustActor(ctx)
+	brandID, err := requireCurrentBrandID(ctx)
+	if err != nil {
+		return err
+	}
 
 	name := strings.TrimSpace(req.Name)
 	if name == "" {
@@ -369,8 +383,8 @@ func (s *KnowledgeService) UpdateGroup(ctx context.Context, groupID int64, req K
 	tag, err := s.pool.Exec(ctx, `
 		UPDATE knowledge_groups
 		SET name = $1, sort_order = $2, updated_at = NOW()
-		WHERE id = $3 AND tenant_id = $4 AND deleted_at IS NULL
-	`, name, sortOrder, groupID, actor.TenantID)
+		WHERE id = $3 AND tenant_id = $4 AND brand_id = $5 AND deleted_at IS NULL
+	`, name, sortOrder, groupID, actor.TenantID, brandID)
 	if err != nil {
 		return response.ErrConflict(40950, "knowledge_group_update_failed", "knowledge group already exists or cannot be updated")
 	}
@@ -382,6 +396,10 @@ func (s *KnowledgeService) UpdateGroup(ctx context.Context, groupID int64, req K
 
 func (s *KnowledgeService) DeleteGroup(ctx context.Context, groupID int64) error {
 	actor := auth.MustActor(ctx)
+	brandID, err := requireCurrentBrandID(ctx)
+	if err != nil {
+		return err
+	}
 
 	tx, err := s.pool.Begin(ctx)
 	if err != nil {
@@ -389,7 +407,7 @@ func (s *KnowledgeService) DeleteGroup(ctx context.Context, groupID int64) error
 	}
 	defer func() { _ = tx.Rollback(ctx) }()
 
-	groupIDs, err := s.listGroupSubtreeIDs(ctx, tx, actor.TenantID, groupID)
+	groupIDs, err := s.listGroupSubtreeIDs(ctx, tx, actor.TenantID, brandID, groupID)
 	if err != nil {
 		return err
 	}
@@ -397,7 +415,7 @@ func (s *KnowledgeService) DeleteGroup(ctx context.Context, groupID int64) error
 		return response.ErrNotFound(40451, "knowledge_group_not_found", "knowledge group not found")
 	}
 
-	itemIDs, err := s.listActiveKnowledgeItemIDs(ctx, tx, actor.TenantID, groupIDs)
+	itemIDs, err := s.listActiveKnowledgeItemIDs(ctx, tx, actor.TenantID, brandID, groupIDs)
 	if err != nil {
 		return err
 	}
@@ -407,9 +425,10 @@ func (s *KnowledgeService) DeleteGroup(ctx context.Context, groupID int64) error
 			UPDATE knowledge_items
 			SET deleted_at = NOW(), updated_at = NOW(), status = 'deleted'
 			WHERE tenant_id = $1
+			  AND brand_id = $2
 			  AND deleted_at IS NULL
-			  AND id = ANY($2::bigint[])
-		`, actor.TenantID, itemIDs); err != nil {
+			  AND id = ANY($3::bigint[])
+		`, actor.TenantID, brandID, itemIDs); err != nil {
 			return response.ErrInternal(50054, "knowledge_group_delete_failed", "failed to delete knowledge items")
 		}
 
@@ -448,9 +467,10 @@ func (s *KnowledgeService) DeleteGroup(ctx context.Context, groupID int64) error
 		UPDATE knowledge_groups
 		SET deleted_at = NOW(), updated_at = NOW()
 		WHERE tenant_id = $1
+		  AND brand_id = $2
 		  AND deleted_at IS NULL
-		  AND id = ANY($2::bigint[])
-	`, actor.TenantID, groupIDs); err != nil {
+		  AND id = ANY($3::bigint[])
+	`, actor.TenantID, brandID, groupIDs); err != nil {
 		return response.ErrInternal(50054, "knowledge_group_delete_failed", "failed to delete knowledge groups")
 	}
 
@@ -475,8 +495,12 @@ func (s *KnowledgeService) DeleteGroup(ctx context.Context, groupID int64) error
 
 func (s *KnowledgeService) ListItems(ctx context.Context, groupID *int64) ([]KnowledgeItemResponse, error) {
 	actor := auth.MustActor(ctx)
+	brandID, err := requireCurrentBrandID(ctx)
+	if err != nil {
+		return nil, err
+	}
 	if groupID != nil && *groupID > 0 {
-		if err := s.ensureGroupAccessible(ctx, actor.TenantID, *groupID); err != nil {
+		if err := s.ensureGroupAccessible(ctx, actor.TenantID, brandID, *groupID); err != nil {
 			return nil, err
 		}
 	}
@@ -485,23 +509,24 @@ func (s *KnowledgeService) ListItems(ctx context.Context, groupID *int64) ([]Kno
 		SELECT ki.id, ki.group_id, kg.name, ki.name, ki.source_type, ki.source_uri, ki.status,
 		       ki.size_bytes, ki.error_message, ki.created_at, ki.updated_at
 		FROM knowledge_items ki
-		JOIN knowledge_groups kg ON kg.id = ki.group_id AND kg.deleted_at IS NULL
+		JOIN knowledge_groups kg ON kg.id = ki.group_id AND kg.brand_id = ki.brand_id AND kg.deleted_at IS NULL
 		WHERE ki.tenant_id = $1
+		  AND ki.brand_id = $2
 		  AND ki.deleted_at IS NULL
 	`
-	args := []any{actor.TenantID}
+	args := []any{actor.TenantID, brandID}
 	if groupID != nil && *groupID > 0 {
 		query += `
 		  AND ki.group_id IN (
 			  WITH RECURSIVE selected_groups AS (
 				  SELECT id
 				  FROM knowledge_groups
-				  WHERE id = $2 AND tenant_id = $1 AND deleted_at IS NULL
+				  WHERE id = $3 AND tenant_id = $1 AND brand_id = $2 AND deleted_at IS NULL
 				  UNION ALL
 				  SELECT child.id
 				  FROM knowledge_groups child
 				  JOIN selected_groups parent ON child.parent_id = parent.id
-				  WHERE child.tenant_id = $1 AND child.deleted_at IS NULL
+				  WHERE child.tenant_id = $1 AND child.brand_id = $2 AND child.deleted_at IS NULL
 			  )
 			  SELECT id FROM selected_groups
 		  )
@@ -551,6 +576,10 @@ func (s *KnowledgeService) ListItems(ctx context.Context, groupID *int64) ([]Kno
 
 func (s *KnowledgeService) GetItemDetail(ctx context.Context, itemID int64) (*KnowledgeItemDetailResponse, error) {
 	actor := auth.MustActor(ctx)
+	brandID, err := requireCurrentBrandID(ctx)
+	if err != nil {
+		return nil, err
+	}
 
 	var (
 		item                 KnowledgeItemDetailResponse
@@ -560,13 +589,13 @@ func (s *KnowledgeService) GetItemDetail(ctx context.Context, itemID int64) (*Kn
 		createdAt, updatedAt time.Time
 	)
 
-	err := s.pool.QueryRow(ctx, `
+	err = s.pool.QueryRow(ctx, `
 		SELECT ki.id, ki.group_id, kg.name, ki.name, ki.source_type, ki.source_uri, ki.status,
 		       ki.size_bytes, ki.error_message, ki.markdown_content, ki.created_at, ki.updated_at
 		FROM knowledge_items ki
-		JOIN knowledge_groups kg ON kg.id = ki.group_id AND kg.deleted_at IS NULL
-		WHERE ki.id = $1 AND ki.tenant_id = $2 AND ki.deleted_at IS NULL
-	`, itemID, actor.TenantID).Scan(
+		JOIN knowledge_groups kg ON kg.id = ki.group_id AND kg.brand_id = ki.brand_id AND kg.deleted_at IS NULL
+		WHERE ki.id = $1 AND ki.tenant_id = $2 AND ki.brand_id = $3 AND ki.deleted_at IS NULL
+	`, itemID, actor.TenantID, brandID).Scan(
 		&item.ID,
 		&item.GroupID,
 		&item.GroupName,
@@ -597,6 +626,10 @@ func (s *KnowledgeService) GetItemDetail(ctx context.Context, itemID int64) (*Kn
 
 func (s *KnowledgeService) CreateTextItem(ctx context.Context, req KnowledgeTextItemRequest) (*KnowledgeItemResponse, error) {
 	actor := auth.MustActor(ctx)
+	brandID, err := requireCurrentBrandID(ctx)
+	if err != nil {
+		return nil, err
+	}
 
 	if err := s.validateIngestionDependencies("text"); err != nil {
 		return nil, err
@@ -612,7 +645,7 @@ func (s *KnowledgeService) CreateTextItem(ctx context.Context, req KnowledgeText
 		return nil, response.ErrBadRequest(40055, "knowledge_text_name_too_long", "knowledge text name must be at most 20 characters")
 	}
 
-	return s.queueKnowledgeItem(ctx, actor.TenantID, knowledgeIngestInput{
+	return s.queueKnowledgeItem(ctx, actor.TenantID, brandID, knowledgeIngestInput{
 		GroupID:     req.GroupID,
 		Name:        name,
 		SourceType:  "text",
@@ -623,6 +656,10 @@ func (s *KnowledgeService) CreateTextItem(ctx context.Context, req KnowledgeText
 
 func (s *KnowledgeService) CreateURLItem(ctx context.Context, req KnowledgeURLItemRequest) (*KnowledgeItemResponse, error) {
 	actor := auth.MustActor(ctx)
+	brandID, err := requireCurrentBrandID(ctx)
+	if err != nil {
+		return nil, err
+	}
 
 	if err := s.validateIngestionDependencies("website"); err != nil {
 		return nil, err
@@ -633,7 +670,7 @@ func (s *KnowledgeService) CreateURLItem(ctx context.Context, req KnowledgeURLIt
 		return nil, response.ErrBadRequest(40052, "knowledge_url_invalid", "knowledge url is invalid")
 	}
 
-	return s.queueKnowledgeItem(ctx, actor.TenantID, knowledgeIngestInput{
+	return s.queueKnowledgeItem(ctx, actor.TenantID, brandID, knowledgeIngestInput{
 		GroupID:    req.GroupID,
 		Name:       strings.TrimSpace(req.Name),
 		SourceType: "website",
@@ -649,6 +686,10 @@ func (s *KnowledgeService) CreateFileItem(
 	content []byte,
 ) (*KnowledgeItemResponse, error) {
 	actor := auth.MustActor(ctx)
+	brandID, err := requireCurrentBrandID(ctx)
+	if err != nil {
+		return nil, err
+	}
 
 	if err := s.validateIngestionDependencies("document"); err != nil {
 		return nil, err
@@ -664,7 +705,7 @@ func (s *KnowledgeService) CreateFileItem(
 		return nil, response.ErrServiceUnavailable(50357, "knowledge_storage_unavailable", err.Error())
 	}
 
-	return s.queueKnowledgeItem(ctx, actor.TenantID, knowledgeIngestInput{
+	return s.queueKnowledgeItem(ctx, actor.TenantID, brandID, knowledgeIngestInput{
 		GroupID:    groupID,
 		Name:       displayName,
 		SourceType: "document",
@@ -675,6 +716,10 @@ func (s *KnowledgeService) CreateFileItem(
 
 func (s *KnowledgeService) DeleteItem(ctx context.Context, itemID int64) error {
 	actor := auth.MustActor(ctx)
+	brandID, err := requireCurrentBrandID(ctx)
+	if err != nil {
+		return err
+	}
 
 	tx, err := s.pool.Begin(ctx)
 	if err != nil {
@@ -685,8 +730,8 @@ func (s *KnowledgeService) DeleteItem(ctx context.Context, itemID int64) error {
 	tag, err := tx.Exec(ctx, `
 		UPDATE knowledge_items
 		SET deleted_at = NOW(), updated_at = NOW(), status = 'deleted'
-		WHERE id = $1 AND tenant_id = $2 AND deleted_at IS NULL
-	`, itemID, actor.TenantID)
+		WHERE id = $1 AND tenant_id = $2 AND brand_id = $3 AND deleted_at IS NULL
+	`, itemID, actor.TenantID, brandID)
 	if err != nil {
 		return response.ErrInternal(50054, "knowledge_item_delete_failed", "failed to delete knowledge item")
 	}
@@ -734,14 +779,18 @@ func (s *KnowledgeService) DeleteItem(ctx context.Context, itemID int64) error {
 
 func (s *KnowledgeService) RetryItem(ctx context.Context, itemID int64) (*KnowledgeItemResponse, error) {
 	actor := auth.MustActor(ctx)
+	brandID, err := requireCurrentBrandID(ctx)
+	if err != nil {
+		return nil, err
+	}
 
 	var sourceType string
 	var status string
-	err := s.pool.QueryRow(ctx, `
+	err = s.pool.QueryRow(ctx, `
 		SELECT source_type, status
 		FROM knowledge_items
-		WHERE id = $1 AND tenant_id = $2 AND deleted_at IS NULL
-	`, itemID, actor.TenantID).Scan(&sourceType, &status)
+		WHERE id = $1 AND tenant_id = $2 AND brand_id = $3 AND deleted_at IS NULL
+	`, itemID, actor.TenantID, brandID).Scan(&sourceType, &status)
 	if err != nil {
 		if errors.Is(err, pgx.ErrNoRows) {
 			return nil, response.ErrNotFound(40450, "knowledge_item_not_found", "knowledge item not found")
@@ -793,9 +842,10 @@ func (s *KnowledgeService) RetryItem(ctx context.Context, itemID int64) (*Knowle
 		    updated_at = NOW()
 		WHERE id = $1
 		  AND tenant_id = $2
+		  AND brand_id = $3
 		  AND deleted_at IS NULL
 		  AND status = 'failed'
-	`, itemID, actor.TenantID)
+	`, itemID, actor.TenantID, brandID)
 	if err != nil {
 		return nil, response.ErrInternal(50055, "knowledge_item_retry_failed", "failed to reset knowledge item")
 	}
@@ -816,7 +866,7 @@ func (s *KnowledgeService) RetryItem(ctx context.Context, itemID int64) (*Knowle
 		return nil, response.ErrServiceUnavailable(50356, "knowledge_queue_unavailable", "knowledge parse queue is busy, please retry")
 	}
 
-	items, err := s.listKnowledgeItemsByIDs(ctx, actor.TenantID, []int64{itemID})
+	items, err := s.listKnowledgeItemsByIDs(ctx, actor.TenantID, brandID, []int64{itemID})
 	if err != nil {
 		return nil, err
 	}
@@ -829,6 +879,7 @@ func (s *KnowledgeService) RetryItem(ctx context.Context, itemID int64) (*Knowle
 func (s *KnowledgeService) ResolveContext(
 	ctx context.Context,
 	tenantID int64,
+	brandID int64,
 	groupIDs []int64,
 	query string,
 ) (*KnowledgeContext, error) {
@@ -871,7 +922,7 @@ func (s *KnowledgeService) ResolveContext(
 		return nil, response.ErrServiceUnavailable(50352, "qdrant_unavailable", err.Error())
 	}
 
-	searchGroupIDs, groupNames, err := s.resolveKnowledgeSearchScope(ctx, tenantID, requestedGroupIDs)
+	searchGroupIDs, groupNames, err := s.resolveKnowledgeSearchScope(ctx, tenantID, brandID, requestedGroupIDs)
 	if err != nil {
 		return nil, err
 	}
@@ -883,7 +934,7 @@ func (s *KnowledgeService) ResolveContext(
 		GroupIDs:     searchGroupIDs,
 		GroupNames:   groupNames,
 		Snippets:     []KnowledgeSnippet{},
-		PreciseFacts: s.collectKnowledgeContextPreciseFacts(ctx, tenantID, searchGroupIDs, nil),
+		PreciseFacts: s.collectKnowledgeContextPreciseFacts(ctx, tenantID, brandID, searchGroupIDs, nil),
 	}
 
 	vectors, err := s.provider.Embed(ctx, queries)
@@ -903,6 +954,7 @@ func (s *KnowledgeService) ResolveContext(
 		points, err := s.store.Search(ctx, retrieval.SearchRequest{
 			Vector:   vector,
 			TenantID: tenantID,
+			BrandID:  brandID,
 			GroupIDs: searchGroupIDs,
 			Limit:    runtimeCfg.RecallLimit,
 		})
@@ -922,7 +974,7 @@ func (s *KnowledgeService) ResolveContext(
 		return baseContext, nil
 	}
 
-	candidates, err = s.filterActiveKnowledgeSnippets(ctx, tenantID, candidates)
+	candidates, err = s.filterActiveKnowledgeSnippets(ctx, tenantID, brandID, candidates)
 	if err != nil {
 		return nil, err
 	}
@@ -939,17 +991,17 @@ func (s *KnowledgeService) ResolveContext(
 	reranked, err := s.provider.Rerank(ctx, rerankQuery, documents, minInt(runtimeCfg.RerankTopN, len(documents)))
 	if err != nil {
 		selected := selectKnowledgeCandidateSnippets(candidates, runtimeCfg.RerankTopN)
-		selected = s.enrichKnowledgePromptSnippets(ctx, tenantID, selected)
+		selected = s.enrichKnowledgePromptSnippets(ctx, tenantID, brandID, selected)
 		baseContext.Snippets = selected
-		baseContext.PreciseFacts = s.collectKnowledgeContextPreciseFacts(ctx, tenantID, searchGroupIDs, selected)
+		baseContext.PreciseFacts = s.collectKnowledgeContextPreciseFacts(ctx, tenantID, brandID, searchGroupIDs, selected)
 		s.logKnowledgeResolve(baseContext, tenantID, rerankQuery, "rerank_failed_fallback", queryRewriteStage, queryRewriteModel, candidates, selected)
 		return baseContext, nil
 	}
 
 	selected := selectKnowledgeRerankedSnippets(candidates, reranked, runtimeCfg.RerankTopN)
-	selected = s.enrichKnowledgePromptSnippets(ctx, tenantID, selected)
+	selected = s.enrichKnowledgePromptSnippets(ctx, tenantID, brandID, selected)
 	baseContext.Snippets = selected
-	baseContext.PreciseFacts = s.collectKnowledgeContextPreciseFacts(ctx, tenantID, searchGroupIDs, selected)
+	baseContext.PreciseFacts = s.collectKnowledgeContextPreciseFacts(ctx, tenantID, brandID, searchGroupIDs, selected)
 	s.logKnowledgeResolve(baseContext, tenantID, rerankQuery, "resolved", queryRewriteStage, queryRewriteModel, candidates, selected)
 	return baseContext, nil
 }
@@ -1341,6 +1393,7 @@ type knowledgePromptItemRecord struct {
 func (s *KnowledgeService) enrichKnowledgePromptSnippets(
 	ctx context.Context,
 	tenantID int64,
+	brandID int64,
 	snippets []KnowledgeSnippet,
 ) []KnowledgeSnippet {
 	if len(snippets) == 0 {
@@ -1358,7 +1411,7 @@ func (s *KnowledgeService) enrichKnowledgePromptSnippets(
 		return snippets
 	}
 
-	items, err := s.loadKnowledgePromptItems(ctx, tenantID, itemIDs)
+	items, err := s.loadKnowledgePromptItems(ctx, tenantID, brandID, itemIDs)
 	if err != nil {
 		if s.logger != nil {
 			s.logger.Warn("load knowledge prompt items failed", zap.Error(err))
@@ -1395,6 +1448,7 @@ func (s *KnowledgeService) enrichKnowledgePromptSnippets(
 func (s *KnowledgeService) loadKnowledgePromptItems(
 	ctx context.Context,
 	tenantID int64,
+	brandID int64,
 	itemIDs []int64,
 ) ([]knowledgePromptItemRecord, error) {
 	if len(itemIDs) == 0 {
@@ -1404,12 +1458,13 @@ func (s *KnowledgeService) loadKnowledgePromptItems(
 	rows, err := s.pool.Query(ctx, `
 		SELECT ki.id, ki.group_id, kg.name, ki.name, ki.source_type, ki.source_uri, ki.content_text, ki.markdown_content
 		FROM knowledge_items ki
-		JOIN knowledge_groups kg ON kg.id = ki.group_id AND kg.deleted_at IS NULL
+		JOIN knowledge_groups kg ON kg.id = ki.group_id AND kg.brand_id = ki.brand_id AND kg.deleted_at IS NULL
 		WHERE ki.tenant_id = $1
-		  AND ki.id = ANY($2::bigint[])
+		  AND ki.brand_id = $2
+		  AND ki.id = ANY($3::bigint[])
 		  AND ki.status = 'completed'
 		  AND ki.deleted_at IS NULL
-	`, tenantID, itemIDs)
+	`, tenantID, brandID, itemIDs)
 	if err != nil {
 		return nil, response.ErrInternal(50051, "knowledge_items_query_failed", "failed to load knowledge prompt items")
 	}
@@ -1438,6 +1493,7 @@ func (s *KnowledgeService) loadKnowledgePromptItems(
 func (s *KnowledgeService) collectKnowledgeContextPreciseFacts(
 	ctx context.Context,
 	tenantID int64,
+	brandID int64,
 	groupIDs []int64,
 	snippets []KnowledgeSnippet,
 ) []string {
@@ -1454,7 +1510,7 @@ func (s *KnowledgeService) collectKnowledgeContextPreciseFacts(
 	}
 	matchedItemIDs = normalizeInt64IDs(matchedItemIDs)
 
-	items, err := s.loadKnowledgePromptItemsByGroupIDs(ctx, tenantID, groupIDs, matchedItemIDs, 24)
+	items, err := s.loadKnowledgePromptItemsByGroupIDs(ctx, tenantID, brandID, groupIDs, matchedItemIDs, 24)
 	if err != nil {
 		if s.logger != nil {
 			s.logger.Warn("collect knowledge context precise facts failed", zap.Error(err))
@@ -1506,6 +1562,7 @@ func (s *KnowledgeService) collectKnowledgeContextPreciseFacts(
 func (s *KnowledgeService) loadKnowledgePromptItemsByGroupIDs(
 	ctx context.Context,
 	tenantID int64,
+	brandID int64,
 	groupIDs []int64,
 	prioritizedItemIDs []int64,
 	limit int,
@@ -1524,31 +1581,34 @@ func (s *KnowledgeService) loadKnowledgePromptItemsByGroupIDs(
 			SELECT id
 			FROM knowledge_groups
 			WHERE tenant_id = $1
-			  AND id = ANY($2::bigint[])
+			  AND brand_id = $2
+			  AND id = ANY($3::bigint[])
 			  AND deleted_at IS NULL
 			UNION ALL
 			SELECT child.id
 			FROM knowledge_groups child
 			JOIN selected_groups parent ON child.parent_id = parent.id
 			WHERE child.tenant_id = $1
+			  AND child.brand_id = $2
 			  AND child.deleted_at IS NULL
 		)
 		SELECT ki.id, ki.group_id, kg.name, ki.name, ki.source_type, ki.source_uri, ki.content_text, ki.markdown_content
 		FROM knowledge_items ki
-		JOIN knowledge_groups kg ON kg.id = ki.group_id AND kg.deleted_at IS NULL
+		JOIN knowledge_groups kg ON kg.id = ki.group_id AND kg.brand_id = ki.brand_id AND kg.deleted_at IS NULL
 		WHERE ki.tenant_id = $1
+		  AND ki.brand_id = $2
 		  AND ki.status = 'completed'
 		  AND ki.deleted_at IS NULL
 		  AND ki.group_id IN (SELECT id FROM selected_groups)
 		ORDER BY
 		  CASE
-		    WHEN ki.id = ANY($3::bigint[]) THEN 0
+		    WHEN ki.id = ANY($4::bigint[]) THEN 0
 		    ELSE 1
 		  END,
 		  ki.updated_at DESC,
 		  ki.id DESC
-		LIMIT $4
-	`, tenantID, groupIDs, prioritizedItemIDs, limit)
+		LIMIT $5
+	`, tenantID, brandID, groupIDs, prioritizedItemIDs, limit)
 	if err != nil {
 		return nil, response.ErrInternal(50051, "knowledge_items_query_failed", "failed to load knowledge prompt items by groups")
 	}
@@ -1859,9 +1919,10 @@ func (s *KnowledgeService) validateIngestionDependencies(sourceType string) erro
 func (s *KnowledgeService) queueKnowledgeItem(
 	ctx context.Context,
 	tenantID int64,
+	brandID int64,
 	input knowledgeIngestInput,
 ) (*KnowledgeItemResponse, error) {
-	resolvedGroupID, err := s.resolveKnowledgeStorageGroupID(ctx, tenantID, input.GroupID)
+	resolvedGroupID, err := s.resolveKnowledgeStorageGroupID(ctx, tenantID, brandID, input.GroupID)
 	if err != nil {
 		return nil, err
 	}
@@ -1880,7 +1941,7 @@ func (s *KnowledgeService) queueKnowledgeItem(
 		input.ContentText = &contentText
 	}
 
-	itemID, parseTaskID, err := s.createPendingKnowledgeItem(ctx, tenantID, input)
+	itemID, parseTaskID, err := s.createPendingKnowledgeItem(ctx, tenantID, brandID, input)
 	if err != nil {
 		return nil, err
 	}
@@ -1894,7 +1955,7 @@ func (s *KnowledgeService) queueKnowledgeItem(
 		return nil, response.ErrServiceUnavailable(50356, "knowledge_queue_unavailable", "knowledge parse queue is busy, please retry")
 	}
 
-	items, err := s.listKnowledgeItemsByIDs(ctx, tenantID, []int64{itemID})
+	items, err := s.listKnowledgeItemsByIDs(ctx, tenantID, brandID, []int64{itemID})
 	if err != nil {
 		return nil, err
 	}
@@ -2064,6 +2125,7 @@ func (s *KnowledgeService) executeParseJob(ctx context.Context, job knowledgePar
 			Vector: embeddings[index],
 			Payload: map[string]any{
 				"tenant_id":    job.TenantID,
+				"brand_id":     item.BrandID,
 				"group_id":     item.GroupID,
 				"group_name":   item.GroupName,
 				"item_id":      item.ID,
@@ -2105,14 +2167,15 @@ func (s *KnowledgeService) loadKnowledgeItemForParse(
 	var contentText *string
 	var markdownContent *string
 	err := s.pool.QueryRow(ctx, `
-		SELECT ki.id, ki.tenant_id, ki.group_id, kg.name, ki.name, ki.source_type,
+		SELECT ki.id, ki.tenant_id, ki.brand_id, ki.group_id, kg.name, ki.name, ki.source_type,
 		       ki.source_uri, ki.storage_key, ki.content_text, ki.markdown_content, ki.item_version
 		FROM knowledge_items ki
-		JOIN knowledge_groups kg ON kg.id = ki.group_id
+		JOIN knowledge_groups kg ON kg.id = ki.group_id AND kg.brand_id = ki.brand_id
 		WHERE ki.id = $1 AND ki.tenant_id = $2 AND ki.deleted_at IS NULL
 	`, itemID, tenantID).Scan(
 		&record.ID,
 		&record.TenantID,
+		&record.BrandID,
 		&record.GroupID,
 		&record.GroupName,
 		&record.Name,
@@ -2166,6 +2229,7 @@ type knowledgeChunkMetaInput struct {
 func (s *KnowledgeService) createPendingKnowledgeItem(
 	ctx context.Context,
 	tenantID int64,
+	brandID int64,
 	input knowledgeIngestInput,
 ) (int64, int64, error) {
 	tx, err := s.pool.Begin(ctx)
@@ -2177,12 +2241,12 @@ func (s *KnowledgeService) createPendingKnowledgeItem(
 	var itemID int64
 	err = tx.QueryRow(ctx, `
 		INSERT INTO knowledge_items (
-			tenant_id, group_id, source_type, name, source_uri, storage_key,
+			tenant_id, brand_id, group_id, source_type, name, source_uri, storage_key,
 			content_text, markdown_content, status, size_bytes, item_version
 		)
-		VALUES ($1, $2, $3, $4, $5, $6, $7, NULL, 'pending', $8, 1)
+		VALUES ($1, $2, $3, $4, $5, $6, $7, $8, NULL, 'pending', $9, 1)
 		RETURNING id
-	`, tenantID, input.GroupID, input.SourceType, input.Name, input.SourceURI, input.StorageKey, input.ContentText, input.SizeBytes).Scan(&itemID)
+	`, tenantID, brandID, input.GroupID, input.SourceType, input.Name, input.SourceURI, input.StorageKey, input.ContentText, input.SizeBytes).Scan(&itemID)
 	if err != nil {
 		return 0, 0, response.ErrConflict(40951, "knowledge_item_create_failed", "failed to create knowledge item")
 	}
@@ -2434,15 +2498,15 @@ func buildKnowledgeSearchText(input knowledgeSearchTextInput) string {
 	return strings.Join(metadata, "\n")
 }
 
-func (s *KnowledgeService) ensureGroupAccessible(ctx context.Context, tenantID, groupID int64) error {
+func (s *KnowledgeService) ensureGroupAccessible(ctx context.Context, tenantID, brandID, groupID int64) error {
 	var exists bool
 	err := s.pool.QueryRow(ctx, `
 		SELECT EXISTS(
 			SELECT 1
 			FROM knowledge_groups
-			WHERE id = $1 AND tenant_id = $2 AND deleted_at IS NULL
+			WHERE id = $1 AND tenant_id = $2 AND brand_id = $3 AND deleted_at IS NULL
 		)
-	`, groupID, tenantID).Scan(&exists)
+	`, groupID, tenantID, brandID).Scan(&exists)
 	if err != nil {
 		return response.ErrInternal(50050, "knowledge_group_query_failed", "failed to query knowledge group")
 	}
@@ -2452,8 +2516,8 @@ func (s *KnowledgeService) ensureGroupAccessible(ctx context.Context, tenantID,
 	return nil
 }
 
-func (s *KnowledgeService) ensureRootGroup(ctx context.Context, tenantID, groupID int64) error {
-	if err := s.ensureGroupAccessible(ctx, tenantID, groupID); err != nil {
+func (s *KnowledgeService) ensureRootGroup(ctx context.Context, tenantID, brandID, groupID int64) error {
+	if err := s.ensureGroupAccessible(ctx, tenantID, brandID, groupID); err != nil {
 		return err
 	}
 
@@ -2464,10 +2528,11 @@ func (s *KnowledgeService) ensureRootGroup(ctx context.Context, tenantID, groupI
 			FROM knowledge_groups
 			WHERE id = $1
 			  AND tenant_id = $2
+			  AND brand_id = $3
 			  AND deleted_at IS NULL
 			  AND parent_id IS NULL
 		)
-	`, groupID, tenantID).Scan(&isRoot)
+	`, groupID, tenantID, brandID).Scan(&isRoot)
 	if err != nil {
 		return response.ErrInternal(50050, "knowledge_group_query_failed", "failed to query knowledge group")
 	}
@@ -2477,8 +2542,8 @@ func (s *KnowledgeService) ensureRootGroup(ctx context.Context, tenantID, groupI
 	return nil
 }
 
-func (s *KnowledgeService) ensureStorableGroup(ctx context.Context, tenantID, groupID int64) error {
-	if err := s.ensureGroupAccessible(ctx, tenantID, groupID); err != nil {
+func (s *KnowledgeService) ensureStorableGroup(ctx context.Context, tenantID, brandID, groupID int64) error {
+	if err := s.ensureGroupAccessible(ctx, tenantID, brandID, groupID); err != nil {
 		return err
 	}
 
@@ -2490,13 +2555,15 @@ func (s *KnowledgeService) ensureStorableGroup(ctx context.Context, tenantID, gr
 			JOIN knowledge_groups parent
 			  ON parent.id = child.parent_id
 			 AND parent.tenant_id = child.tenant_id
+			 AND parent.brand_id = child.brand_id
 			 AND parent.deleted_at IS NULL
 			WHERE child.id = $1
 			  AND child.tenant_id = $2
+			  AND child.brand_id = $3
 			  AND child.deleted_at IS NULL
 			  AND parent.parent_id IS NULL
 		)
-	`, groupID, tenantID).Scan(&storable)
+	`, groupID, tenantID, brandID).Scan(&storable)
 	if err != nil {
 		return response.ErrInternal(50050, "knowledge_group_query_failed", "failed to query knowledge group")
 	}
@@ -2506,14 +2573,14 @@ func (s *KnowledgeService) ensureStorableGroup(ctx context.Context, tenantID, gr
 	return nil
 }
 
-func (s *KnowledgeService) resolveKnowledgeStorageGroupID(ctx context.Context, tenantID, groupID int64) (int64, error) {
+func (s *KnowledgeService) resolveKnowledgeStorageGroupID(ctx context.Context, tenantID, brandID, groupID int64) (int64, error) {
 	tx, err := s.pool.Begin(ctx)
 	if err != nil {
 		return 0, response.ErrInternal(50055, "knowledge_group_resolve_failed", "failed to begin knowledge group transaction")
 	}
 	defer func() { _ = tx.Rollback(ctx) }()
 
-	resolvedGroupID, err := s.resolveKnowledgeStorageGroupIDTx(ctx, tx, tenantID, groupID)
+	resolvedGroupID, err := s.resolveKnowledgeStorageGroupIDTx(ctx, tx, tenantID, brandID, groupID)
 	if err != nil {
 		return 0, err
 	}
@@ -2527,15 +2594,15 @@ func (s *KnowledgeService) resolveKnowledgeStorageGroupID(ctx context.Context, t
 func (s *KnowledgeService) resolveKnowledgeStorageGroupIDTx(
 	ctx context.Context,
 	tx pgx.Tx,
-	tenantID, groupID int64,
+	tenantID, brandID, groupID int64,
 ) (int64, error) {
 	var parentID *int64
 	if err := tx.QueryRow(ctx, `
 		SELECT parent_id
 		FROM knowledge_groups
-		WHERE id = $1 AND tenant_id = $2 AND deleted_at IS NULL
+		WHERE id = $1 AND tenant_id = $2 AND brand_id = $3 AND deleted_at IS NULL
 		FOR UPDATE
-	`, groupID, tenantID).Scan(&parentID); err != nil {
+	`, groupID, tenantID, brandID).Scan(&parentID); err != nil {
 		if errors.Is(err, pgx.ErrNoRows) {
 			return 0, response.ErrNotFound(40451, "knowledge_group_not_found", "knowledge group not found")
 		}
@@ -2547,8 +2614,8 @@ func (s *KnowledgeService) resolveKnowledgeStorageGroupIDTx(
 		if err := tx.QueryRow(ctx, `
 			SELECT parent_id
 			FROM knowledge_groups
-			WHERE id = $1 AND tenant_id = $2 AND deleted_at IS NULL
-		`, *parentID, tenantID).Scan(&grandParentID); err != nil {
+			WHERE id = $1 AND tenant_id = $2 AND brand_id = $3 AND deleted_at IS NULL
+		`, *parentID, tenantID, brandID).Scan(&grandParentID); err != nil {
 			if errors.Is(err, pgx.ErrNoRows) {
 				return 0, response.ErrNotFound(40451, "knowledge_group_not_found", "knowledge group not found")
 			}
@@ -2565,22 +2632,23 @@ func (s *KnowledgeService) resolveKnowledgeStorageGroupIDTx(
 		SELECT id
 		FROM knowledge_groups
 		WHERE tenant_id = $1
-		  AND parent_id = $2
-		  AND name = $3
+		  AND brand_id = $2
+		  AND parent_id = $3
+		  AND name = $4
 		  AND deleted_at IS NULL
 		ORDER BY id
 		LIMIT 1
-	`, tenantID, groupID, defaultKnowledgeChildGroupName).Scan(&childGroupID); err == nil {
+	`, tenantID, brandID, groupID, defaultKnowledgeChildGroupName).Scan(&childGroupID); err == nil {
 		return childGroupID, nil
 	} else if !errors.Is(err, pgx.ErrNoRows) {
 		return 0, response.ErrInternal(50050, "knowledge_group_query_failed", "failed to query knowledge group")
 	}
 
 	if err := tx.QueryRow(ctx, `
-		INSERT INTO knowledge_groups (tenant_id, name, parent_id, sort_order)
-		VALUES ($1, $2, $3, 0)
+		INSERT INTO knowledge_groups (tenant_id, brand_id, name, parent_id, sort_order)
+		VALUES ($1, $2, $3, $4, 0)
 		RETURNING id
-	`, tenantID, defaultKnowledgeChildGroupName, groupID).Scan(&childGroupID); err == nil {
+	`, tenantID, brandID, defaultKnowledgeChildGroupName, groupID).Scan(&childGroupID); err == nil {
 		return childGroupID, nil
 	}
 
@@ -2588,12 +2656,13 @@ func (s *KnowledgeService) resolveKnowledgeStorageGroupIDTx(
 		SELECT id
 		FROM knowledge_groups
 		WHERE tenant_id = $1
-		  AND parent_id = $2
-		  AND name = $3
+		  AND brand_id = $2
+		  AND parent_id = $3
+		  AND name = $4
 		  AND deleted_at IS NULL
 		ORDER BY id
 		LIMIT 1
-	`, tenantID, groupID, defaultKnowledgeChildGroupName).Scan(&childGroupID); err != nil {
+	`, tenantID, brandID, groupID, defaultKnowledgeChildGroupName).Scan(&childGroupID); err != nil {
 		return 0, response.ErrConflict(40950, "knowledge_group_create_failed", "failed to create default knowledge group")
 	}
 	return childGroupID, nil
@@ -2602,22 +2671,22 @@ func (s *KnowledgeService) resolveKnowledgeStorageGroupIDTx(
 func (s *KnowledgeService) listGroupSubtreeIDs(
 	ctx context.Context,
 	tx pgx.Tx,
-	tenantID, groupID int64,
+	tenantID, brandID, groupID int64,
 ) ([]int64, error) {
 	rows, err := tx.Query(ctx, `
 		WITH RECURSIVE selected_groups AS (
 			SELECT id
 			FROM knowledge_groups
-			WHERE id = $1 AND tenant_id = $2 AND deleted_at IS NULL
+			WHERE id = $1 AND tenant_id = $2 AND brand_id = $3 AND deleted_at IS NULL
 			UNION ALL
 			SELECT child.id
 			FROM knowledge_groups child
 			JOIN selected_groups parent ON child.parent_id = parent.id
-			WHERE child.tenant_id = $2 AND child.deleted_at IS NULL
+			WHERE child.tenant_id = $2 AND child.brand_id = $3 AND child.deleted_at IS NULL
 		)
 		SELECT id
 		FROM selected_groups
-	`, groupID, tenantID)
+	`, groupID, tenantID, brandID)
 	if err != nil {
 		return nil, response.ErrInternal(50054, "knowledge_group_delete_failed", "failed to query knowledge groups")
 	}
@@ -2638,6 +2707,7 @@ func (s *KnowledgeService) listActiveKnowledgeItemIDs(
 	ctx context.Context,
 	tx pgx.Tx,
 	tenantID int64,
+	brandID int64,
 	groupIDs []int64,
 ) ([]int64, error) {
 	if len(groupIDs) == 0 {
@@ -2648,9 +2718,10 @@ func (s *KnowledgeService) listActiveKnowledgeItemIDs(
 		SELECT id
 		FROM knowledge_items
 		WHERE tenant_id = $1
+		  AND brand_id = $2
 		  AND deleted_at IS NULL
-		  AND group_id = ANY($2::bigint[])
-	`, tenantID, groupIDs)
+		  AND group_id = ANY($3::bigint[])
+	`, tenantID, brandID, groupIDs)
 	if err != nil {
 		return nil, response.ErrInternal(50054, "knowledge_group_delete_failed", "failed to query knowledge items")
 	}
@@ -2714,6 +2785,7 @@ func (s *KnowledgeService) listKnowledgePointIDs(ctx context.Context, tenantID,
 func (s *KnowledgeService) filterActiveKnowledgeSnippets(
 	ctx context.Context,
 	tenantID int64,
+	brandID int64,
 	candidates []KnowledgeSnippet,
 ) ([]KnowledgeSnippet, error) {
 	if len(candidates) == 0 {
@@ -2735,10 +2807,11 @@ func (s *KnowledgeService) filterActiveKnowledgeSnippets(
 		SELECT id
 		FROM knowledge_items
 		WHERE tenant_id = $1
-		  AND id = ANY($2::bigint[])
+		  AND brand_id = $2
+		  AND id = ANY($3::bigint[])
 		  AND status = 'completed'
 		  AND deleted_at IS NULL
-	`, tenantID, itemIDs)
+	`, tenantID, brandID, itemIDs)
 	if err != nil {
 		return nil, response.ErrInternal(50051, "knowledge_items_query_failed", "failed to filter deleted knowledge items")
 	}
@@ -2852,14 +2925,15 @@ func (s *KnowledgeService) loadKnowledgeItemForCleanup(
 	var contentText *string
 	var markdownContent *string
 	err := s.pool.QueryRow(ctx, `
-		SELECT ki.id, ki.tenant_id, ki.group_id, kg.name, ki.name, ki.source_type,
+		SELECT ki.id, ki.tenant_id, ki.brand_id, ki.group_id, kg.name, ki.name, ki.source_type,
 		       ki.source_uri, ki.storage_key, ki.content_text, ki.markdown_content, ki.item_version
 		FROM knowledge_items ki
-		JOIN knowledge_groups kg ON kg.id = ki.group_id
+		JOIN knowledge_groups kg ON kg.id = ki.group_id AND kg.brand_id = ki.brand_id
 		WHERE ki.id = $1 AND ki.tenant_id = $2 AND ki.deleted_at IS NOT NULL
 	`, itemID, tenantID).Scan(
 		&record.ID,
 		&record.TenantID,
+		&record.BrandID,
 		&record.GroupID,
 		&record.GroupName,
 		&record.Name,
@@ -2925,7 +2999,7 @@ func (s *KnowledgeService) clearKnowledgeCleanupError(ctx context.Context, tenan
 	return err
 }
 
-func (s *KnowledgeService) listKnowledgeItemsByIDs(ctx context.Context, tenantID int64, itemIDs []int64) ([]KnowledgeItemResponse, error) {
+func (s *KnowledgeService) listKnowledgeItemsByIDs(ctx context.Context, tenantID, brandID int64, itemIDs []int64) ([]KnowledgeItemResponse, error) {
 	if len(itemIDs) == 0 {
 		return []KnowledgeItemResponse{}, nil
 	}
@@ -2933,10 +3007,10 @@ func (s *KnowledgeService) listKnowledgeItemsByIDs(ctx context.Context, tenantID
 		SELECT ki.id, ki.group_id, kg.name, ki.name, ki.source_type, ki.source_uri, ki.status,
 		       ki.size_bytes, ki.error_message, ki.created_at, ki.updated_at
 		FROM knowledge_items ki
-		JOIN knowledge_groups kg ON kg.id = ki.group_id
-		WHERE ki.tenant_id = $1 AND ki.id = ANY($2::bigint[]) AND ki.deleted_at IS NULL
+		JOIN knowledge_groups kg ON kg.id = ki.group_id AND kg.brand_id = ki.brand_id
+		WHERE ki.tenant_id = $1 AND ki.brand_id = $2 AND ki.id = ANY($3::bigint[]) AND ki.deleted_at IS NULL
 		ORDER BY ki.created_at DESC, ki.id DESC
-	`, tenantID, itemIDs)
+	`, tenantID, brandID, itemIDs)
 	if err != nil {
 		return nil, response.ErrInternal(50051, "knowledge_items_query_failed", "failed to list knowledge items")
 	}
@@ -2974,7 +3048,7 @@ func (s *KnowledgeService) listKnowledgeItemsByIDs(ctx context.Context, tenantID
 	return items, nil
 }
 
-func (s *KnowledgeService) resolveKnowledgeSearchScope(ctx context.Context, tenantID int64, groupIDs []int64) ([]int64, []string, error) {
+func (s *KnowledgeService) resolveKnowledgeSearchScope(ctx context.Context, tenantID, brandID int64, groupIDs []int64) ([]int64, []string, error) {
 	groupIDs = normalizeInt64IDs(groupIDs)
 	if len(groupIDs) == 0 {
 		return []int64{}, []string{}, nil
@@ -2985,19 +3059,21 @@ func (s *KnowledgeService) resolveKnowledgeSearchScope(ctx context.Context, tena
 			SELECT id, name, parent_id, sort_order, created_at
 			FROM knowledge_groups
 			WHERE tenant_id = $1
-			  AND id = ANY($2::bigint[])
+			  AND brand_id = $2
+			  AND id = ANY($3::bigint[])
 			  AND deleted_at IS NULL
 			UNION
 			SELECT child.id, child.name, child.parent_id, child.sort_order, child.created_at
 			FROM knowledge_groups child
 			JOIN selected_groups parent ON child.parent_id = parent.id
 			WHERE child.tenant_id = $1
+			  AND child.brand_id = $2
 			  AND child.deleted_at IS NULL
 		)
 		SELECT id, name
 		FROM selected_groups
 		ORDER BY sort_order, created_at, id
-	`, tenantID, groupIDs)
+	`, tenantID, brandID, groupIDs)
 	if err != nil {
 		return nil, nil, response.ErrInternal(50050, "knowledge_group_query_failed", "failed to query knowledge groups")
 	}
diff --git a/server/internal/tenant/app/media_supply_images.go b/server/internal/tenant/app/media_supply_images.go
index fda88bf..1cee887 100644
--- a/server/internal/tenant/app/media_supply_images.go
+++ b/server/internal/tenant/app/media_supply_images.go
@@ -32,15 +32,15 @@ type mediaSupplyArticleImageUpload struct {
 	Content     []byte
 }
 
-func (s *MediaSupplyService) prepareMeijiequanArticleContent(ctx context.Context, tenantID int64, content string) (string, error) {
+func (s *MediaSupplyService) prepareMeijiequanArticleContent(ctx context.Context, tenantID int64, brandID int64, content string) (string, error) {
 	html := meijiequanArticleHTML(content)
 	if strings.TrimSpace(html) == "" {
 		return "", nil
 	}
-	return s.uploadMeijiequanArticleImages(ctx, tenantID, html)
+	return s.uploadMeijiequanArticleImages(ctx, tenantID, brandID, html)
 }
 
-func (s *MediaSupplyService) uploadMeijiequanArticleImages(ctx context.Context, tenantID int64, fragment string) (string, error) {
+func (s *MediaSupplyService) uploadMeijiequanArticleImages(ctx context.Context, tenantID int64, brandID int64, fragment string) (string, error) {
 	if !strings.Contains(strings.ToLower(fragment), "<img") {
 		return fragment, nil
 	}
@@ -56,7 +56,7 @@ func (s *MediaSupplyService) uploadMeijiequanArticleImages(ctx context.Context,
 
 	cache := make(map[string]string)
 	for _, node := range nodes {
-		if err := s.uploadMeijiequanArticleImageNode(ctx, tenantID, node, cache); err != nil {
+		if err := s.uploadMeijiequanArticleImageNode(ctx, tenantID, brandID, node, cache); err != nil {
 			return "", err
 		}
 	}
@@ -70,31 +70,31 @@ func (s *MediaSupplyService) uploadMeijiequanArticleImages(ctx context.Context,
 	return builder.String(), nil
 }
 
-func (s *MediaSupplyService) uploadMeijiequanArticleImageNode(ctx context.Context, tenantID int64, node *nethtml.Node, cache map[string]string) error {
+func (s *MediaSupplyService) uploadMeijiequanArticleImageNode(ctx context.Context, tenantID int64, brandID int64, node *nethtml.Node, cache map[string]string) error {
 	if node == nil {
 		return nil
 	}
 	if node.Type == nethtml.ElementNode && strings.EqualFold(node.Data, "img") {
-		if err := s.uploadMeijiequanArticleImageAttrs(ctx, tenantID, node, cache); err != nil {
+		if err := s.uploadMeijiequanArticleImageAttrs(ctx, tenantID, brandID, node, cache); err != nil {
 			return err
 		}
 	}
 	for child := node.FirstChild; child != nil; child = child.NextSibling {
-		if err := s.uploadMeijiequanArticleImageNode(ctx, tenantID, child, cache); err != nil {
+		if err := s.uploadMeijiequanArticleImageNode(ctx, tenantID, brandID, child, cache); err != nil {
 			return err
 		}
 	}
 	return nil
 }
 
-func (s *MediaSupplyService) uploadMeijiequanArticleImageAttrs(ctx context.Context, tenantID int64, node *nethtml.Node, cache map[string]string) error {
+func (s *MediaSupplyService) uploadMeijiequanArticleImageAttrs(ctx context.Context, tenantID int64, brandID int64, node *nethtml.Node, cache map[string]string) error {
 	src := mediaSupplyHTMLAttrValue(node.Attr, "src")
 	originalSrc := mediaSupplyHTMLAttrValue(node.Attr, "_src")
 	dataSrc := mediaSupplyHTMLAttrValue(node.Attr, "data-src")
 	assetID := mediaSupplyHTMLInt64AttrValue(node.Attr, "data-asset-id")
 	currentURL := firstNonEmptyText(src, originalSrc, dataSrc)
 
-	upload, resolved, err := s.resolveMeijiequanArticleImageUpload(ctx, tenantID, currentURL, assetID)
+	upload, resolved, err := s.resolveMeijiequanArticleImageUpload(ctx, tenantID, brandID, currentURL, assetID)
 	if err != nil {
 		return err
 	}
@@ -158,8 +158,8 @@ func (s *MediaSupplyService) uploadMeijiequanArticleImageAttrs(ctx context.Conte
 	return nil
 }
 
-func (s *MediaSupplyService) resolveMeijiequanArticleImageUpload(ctx context.Context, tenantID int64, imageURL string, assetID int64) (mediaSupplyArticleImageUpload, bool, error) {
-	objectKey, internalAssetURL, ok := s.mediaSupplyObjectKeyFromPublicAssetURL(imageURL, tenantID)
+func (s *MediaSupplyService) resolveMeijiequanArticleImageUpload(ctx context.Context, tenantID int64, brandID int64, imageURL string, assetID int64) (mediaSupplyArticleImageUpload, bool, error) {
+	objectKey, internalAssetURL, ok := s.mediaSupplyObjectKeyFromPublicAssetURL(ctx, imageURL, tenantID, brandID)
 	if internalAssetURL {
 		if !ok {
 			if assetID <= 0 {
@@ -171,7 +171,7 @@ func (s *MediaSupplyService) resolveMeijiequanArticleImageUpload(ctx context.Con
 		}
 	}
 	if assetID > 0 {
-		objectKey, err := s.loadMediaSupplyImageAssetObjectKey(ctx, tenantID, assetID)
+		objectKey, err := s.loadMediaSupplyImageAssetObjectKey(ctx, tenantID, brandID, assetID)
 		if err != nil {
 			return mediaSupplyArticleImageUpload{}, false, err
 		}
@@ -259,7 +259,7 @@ func mediaSupplyUploadFilename(objectKey, sourceURL, ext string) string {
 	return name
 }
 
-func (s *MediaSupplyService) mediaSupplyObjectKeyFromPublicAssetURL(raw string, tenantID int64) (string, bool, bool) {
+func (s *MediaSupplyService) mediaSupplyObjectKeyFromPublicAssetURL(ctx context.Context, raw string, tenantID int64, brandID int64) (string, bool, bool) {
 	token, ok := mediaSupplyPublicAssetTokenFromURL(raw)
 	if !ok {
 		return "", false, false
@@ -268,6 +268,9 @@ func (s *MediaSupplyService) mediaSupplyObjectKeyFromPublicAssetURL(raw string,
 	if !valid || !mediaSupplyObjectKeyAllowedForTenant(objectKey, tenantID) {
 		return "", true, false
 	}
+	if !s.mediaSupplyImageObjectKeyBelongsToBrand(ctx, tenantID, brandID, objectKey) {
+		return "", true, false
+	}
 	return objectKey, true, true
 }
 
@@ -317,16 +320,48 @@ func mediaSupplyObjectKeyAllowedForTenant(objectKey string, tenantID int64) bool
 		strings.HasPrefix(objectKey, tenantPrefix+"articles/")
 }
 
-func (s *MediaSupplyService) loadMediaSupplyImageAssetObjectKey(ctx context.Context, tenantID, assetID int64) (string, error) {
+func mediaSupplyObjectKeyIsImageLibraryAsset(objectKey string, tenantID int64) bool {
+	if tenantID <= 0 {
+		return false
+	}
+	tenantPrefix := "tenants/" + strconv.FormatInt(tenantID, 10) + "/"
+	return strings.HasPrefix(strings.TrimSpace(objectKey), tenantPrefix+"images/")
+}
+
+func (s *MediaSupplyService) mediaSupplyImageObjectKeyBelongsToBrand(ctx context.Context, tenantID, brandID int64, objectKey string) bool {
+	if s == nil || s.pool == nil || !mediaSupplyObjectKeyIsImageLibraryAsset(objectKey, tenantID) {
+		return true
+	}
+	if tenantID <= 0 || brandID <= 0 || strings.TrimSpace(objectKey) == "" {
+		return false
+	}
+	var exists bool
+	if err := s.pool.QueryRow(ctx, `
+			SELECT EXISTS (
+				SELECT 1
+				FROM image_assets
+				WHERE tenant_id = $1
+				  AND brand_id = $2
+				  AND object_key = $3
+				  AND status = 'active'
+				  AND deleted_at IS NULL
+			)
+		`, tenantID, brandID, objectKey).Scan(&exists); err != nil {
+		return false
+	}
+	return exists
+}
+
+func (s *MediaSupplyService) loadMediaSupplyImageAssetObjectKey(ctx context.Context, tenantID, brandID, assetID int64) (string, error) {
 	if s == nil || s.pool == nil {
 		return "", errMediaSupplyArticleImageUpload
 	}
 	var objectKey string
 	if err := s.pool.QueryRow(ctx, `
-		SELECT object_key
-		FROM image_assets
-		WHERE id = $1 AND tenant_id = $2 AND status = 'active' AND deleted_at IS NULL
-	`, assetID, tenantID).Scan(&objectKey); err != nil {
+			SELECT object_key
+			FROM image_assets
+			WHERE id = $1 AND tenant_id = $2 AND brand_id = $3 AND status = 'active' AND deleted_at IS NULL
+		`, assetID, tenantID, brandID).Scan(&objectKey); err != nil {
 		if errors.Is(err, pgx.ErrNoRows) {
 			return "", errMediaSupplyArticleImageUpload
 		}
diff --git a/server/internal/tenant/app/media_supply_test.go b/server/internal/tenant/app/media_supply_test.go
index 1a58766..0229059 100644
--- a/server/internal/tenant/app/media_supply_test.go
+++ b/server/internal/tenant/app/media_supply_test.go
@@ -534,7 +534,7 @@ func TestPrepareMeijiequanArticleContentUploadsSaaSImages(t *testing.T) {
 	}).WithObjectStorage(storage)
 	content := `<p class="article-editor-image article-editor-image--center" align="center"><img src="/api/public/assets/` + token + `" alt="" data-asset-id="5" /></p>`
 
-	got, err := svc.prepareMeijiequanArticleContent(context.Background(), 4, content)
+	got, err := svc.prepareMeijiequanArticleContent(context.Background(), 4, 11, content)
 	if err != nil {
 		t.Fatalf("prepare content: %v", err)
 	}
diff --git a/server/internal/tenant/app/media_supply_worker.go b/server/internal/tenant/app/media_supply_worker.go
index 129c192..c3247f2 100644
--- a/server/internal/tenant/app/media_supply_worker.go
+++ b/server/internal/tenant/app/media_supply_worker.go
@@ -32,6 +32,7 @@ type mediaSupplySyncJob struct {
 type mediaSupplySubmitOrder struct {
 	ID                int64
 	TenantID          int64
+	BrandID           int64
 	UserID            int64
 	ModelID           int
 	Title             string
@@ -172,7 +173,7 @@ func (w *MediaSupplyWorker) processOneOrder(ctx context.Context) error {
 	if err := w.refreshOrderCostsBeforeSubmit(ctx, order, items); err != nil {
 		return w.failOrder(ctx, order, err)
 	}
-	content, err := w.service.prepareMeijiequanArticleContent(ctx, order.TenantID, order.ContentSnapshot)
+	content, err := w.service.prepareMeijiequanArticleContent(ctx, order.TenantID, order.BrandID, order.ContentSnapshot)
 	if err != nil {
 		return w.failOrder(ctx, order, err)
 	}
@@ -1143,7 +1144,7 @@ func (w *MediaSupplyWorker) claimSubmitOrder(ctx context.Context) (*mediaSupplyS
 	var order mediaSupplySubmitOrder
 	var requestPayload []byte
 	if err := tx.QueryRow(ctx, `
-		SELECT id, tenant_id, user_id, model_id, title, content_snapshot, remark, order_brand, attempt_count, request_payload_json
+			SELECT id, tenant_id, brand_id, user_id, model_id, title, content_snapshot, remark, order_brand, attempt_count, request_payload_json
 		FROM media_supply_orders
 		WHERE supplier = $1 AND status = $2 AND next_attempt_at <= NOW() AND deleted_at IS NULL
 		ORDER BY queued_at ASC, id ASC
@@ -1152,6 +1153,7 @@ func (w *MediaSupplyWorker) claimSubmitOrder(ctx context.Context) (*mediaSupplyS
 	`, mediaSupplySupplierMeijiequan, mediaSupplyOrderStatusQueued).Scan(
 		&order.ID,
 		&order.TenantID,
+		&order.BrandID,
 		&order.UserID,
 		&order.ModelID,
 		&order.Title,
diff --git a/server/internal/tenant/app/prompt_generate_service.go b/server/internal/tenant/app/prompt_generate_service.go
index eafbf6f..eba5145 100644
--- a/server/internal/tenant/app/prompt_generate_service.go
+++ b/server/internal/tenant/app/prompt_generate_service.go
@@ -355,6 +355,7 @@ func (s *PromptRuleGenerationService) enqueuePromptRuleGeneration(ctx context.Co
 		knowledgeContext, resolveErr := s.knowledge.ResolveContext(
 			ctx,
 			input.TenantID,
+			*input.BrandID,
 			rule.KnowledgeGroupIDs,
 			buildPromptRuleKnowledgeQuery(rule, inputParams),
 		)
diff --git a/server/internal/tenant/app/prompt_rule_service.go b/server/internal/tenant/app/prompt_rule_service.go
index 8a2bc87..70da21c 100644
--- a/server/internal/tenant/app/prompt_rule_service.go
+++ b/server/internal/tenant/app/prompt_rule_service.go
@@ -254,7 +254,7 @@ func (s *PromptRuleService) Create(ctx context.Context, req PromptRuleRequest) (
 	if err != nil {
 		return nil, err
 	}
-	knowledgeGroups, err := s.validatePromptRuleKnowledgeGroups(ctx, actor.TenantID, req.KnowledgeGroupIDs)
+	knowledgeGroups, err := s.validatePromptRuleKnowledgeGroups(ctx, actor.TenantID, brandID, req.KnowledgeGroupIDs)
 	if err != nil {
 		return nil, err
 	}
@@ -325,7 +325,7 @@ func (s *PromptRuleService) Update(ctx context.Context, id int64, req PromptRule
 	if err != nil {
 		return err
 	}
-	knowledgeGroups, err := s.validatePromptRuleKnowledgeGroups(ctx, actor.TenantID, req.KnowledgeGroupIDs)
+	knowledgeGroups, err := s.validatePromptRuleKnowledgeGroups(ctx, actor.TenantID, brandID, req.KnowledgeGroupIDs)
 	if err != nil {
 		return err
 	}
@@ -535,7 +535,7 @@ func (s *PromptRuleService) loadPromptRules(ctx context.Context, tenantID, brand
 		item.KnowledgeGroups = []PromptRuleKnowledgeGroup{}
 		items = append(items, item)
 	}
-	groupMap, err := s.loadPromptRuleKnowledgeGroupMap(ctx, tenantID, collectPromptRuleIDs(items))
+	groupMap, err := s.loadPromptRuleKnowledgeGroupMap(ctx, tenantID, brandID, collectPromptRuleIDs(items))
 	if err != nil {
 		return nil, err
 	}
@@ -572,7 +572,7 @@ func (s *PromptRuleService) loadPromptRuleDetail(ctx context.Context, tenantID,
 	item.UpdatedAt = fmt.Sprintf("%v", updatedAt)
 	item.ArticleCount = articleCount
 
-	groupMap, err := s.loadPromptRuleKnowledgeGroupMap(ctx, tenantID, []int64{ruleID})
+	groupMap, err := s.loadPromptRuleKnowledgeGroupMap(ctx, tenantID, brandID, []int64{ruleID})
 	if err != nil {
 		return nil, false, err
 	}
@@ -630,6 +630,7 @@ func (s *PromptRuleService) validatePromptRuleGroup(ctx context.Context, tenantI
 func (s *PromptRuleService) validatePromptRuleKnowledgeGroups(
 	ctx context.Context,
 	tenantID int64,
+	brandID int64,
 	groupIDs []int64,
 ) ([]PromptRuleKnowledgeGroup, error) {
 	groupIDs = normalizeInt64IDs(groupIDs)
@@ -640,9 +641,9 @@ func (s *PromptRuleService) validatePromptRuleKnowledgeGroups(
 	rows, err := s.pool.Query(ctx, `
 		SELECT id, name
 		FROM knowledge_groups
-		WHERE tenant_id = $1 AND id = ANY($2::bigint[]) AND deleted_at IS NULL
+		WHERE tenant_id = $1 AND brand_id = $2 AND id = ANY($3::bigint[]) AND deleted_at IS NULL
 		ORDER BY sort_order, created_at, id
-	`, tenantID, groupIDs)
+	`, tenantID, brandID, groupIDs)
 	if err != nil {
 		return nil, response.ErrInternal(50010, "knowledge_group_query_failed", "failed to query knowledge groups")
 	}
@@ -669,6 +670,7 @@ func (s *PromptRuleService) validatePromptRuleKnowledgeGroups(
 func (s *PromptRuleService) loadPromptRuleKnowledgeGroupMap(
 	ctx context.Context,
 	tenantID int64,
+	brandID int64,
 	ruleIDs []int64,
 ) (map[int64][]PromptRuleKnowledgeGroup, error) {
 	result := make(map[int64][]PromptRuleKnowledgeGroup, len(ruleIDs))
@@ -683,9 +685,10 @@ func (s *PromptRuleService) loadPromptRuleKnowledgeGroupMap(
 		JOIN knowledge_groups kg ON kg.id = prkg.knowledge_group_id
 		WHERE prkg.prompt_rule_id = ANY($1::bigint[])
 		  AND kg.tenant_id = $2
+		  AND kg.brand_id = $3
 		  AND kg.deleted_at IS NULL
 		ORDER BY kg.sort_order, kg.created_at, kg.id
-	`, ruleIDs, tenantID)
+	`, ruleIDs, tenantID, brandID)
 	if err != nil {
 		return nil, response.ErrInternal(50010, "knowledge_group_query_failed", "failed to query prompt rule knowledge groups")
 	}
diff --git a/server/internal/tenant/app/schedule_task_service.go b/server/internal/tenant/app/schedule_task_service.go
index 71c3288..0152aa6 100644
--- a/server/internal/tenant/app/schedule_task_service.go
+++ b/server/internal/tenant/app/schedule_task_service.go
@@ -1169,7 +1169,11 @@ func (s *ScheduleTaskService) normalizeAutoPublishConfig(ctx context.Context, ac
 	randomScope := ScheduleCoverRandomScopeAll
 	var randomFolderID *int64
 	if coverMode == ScheduleCoverModeRandom {
-		randomScope, randomFolderID, err = s.normalizeScheduleCoverRandomSource(ctx, actor.TenantID, req.CoverRandomScope, req.CoverRandomFolderID)
+		brandID, err := requireCurrentBrandID(ctx)
+		if err != nil {
+			return config, err
+		}
+		randomScope, randomFolderID, err = s.normalizeScheduleCoverRandomSource(ctx, actor.TenantID, brandID, req.CoverRandomScope, req.CoverRandomFolderID)
 		if err != nil {
 			return config, err
 		}
@@ -1218,7 +1222,7 @@ func normalizeScheduleCoverMode(value string) (string, error) {
 	}
 }
 
-func (s *ScheduleTaskService) normalizeScheduleCoverRandomSource(ctx context.Context, tenantID int64, scope string, folderID *int64) (string, *int64, error) {
+func (s *ScheduleTaskService) normalizeScheduleCoverRandomSource(ctx context.Context, tenantID, brandID int64, scope string, folderID *int64) (string, *int64, error) {
 	normalizedScope := strings.TrimSpace(scope)
 	if normalizedScope == "" {
 		normalizedScope = ScheduleCoverRandomScopeAll
@@ -1230,7 +1234,7 @@ func (s *ScheduleTaskService) normalizeScheduleCoverRandomSource(ctx context.Con
 		if folderID == nil || *folderID <= 0 {
 			return "", nil, response.ErrBadRequest(40077, "cover_random_folder_required", "请选择随机封面图片文件夹")
 		}
-		if err := s.ensureImageFolderExists(ctx, tenantID, *folderID); err != nil {
+		if err := s.ensureImageFolderExists(ctx, tenantID, brandID, *folderID); err != nil {
 			return "", nil, err
 		}
 		return ScheduleCoverRandomScopeFolder, folderID, nil
@@ -1239,7 +1243,7 @@ func (s *ScheduleTaskService) normalizeScheduleCoverRandomSource(ctx context.Con
 	}
 }
 
-func (s *ScheduleTaskService) ensureImageFolderExists(ctx context.Context, tenantID, folderID int64) error {
+func (s *ScheduleTaskService) ensureImageFolderExists(ctx context.Context, tenantID, brandID, folderID int64) error {
 	var exists bool
 	if err := s.pool.QueryRow(ctx, `
 		SELECT EXISTS (
@@ -1247,9 +1251,9 @@ func (s *ScheduleTaskService) ensureImageFolderExists(ctx context.Context, tenan
 			FROM image_folders
 			WHERE id = $1
 			  AND tenant_id = $2
-			  AND deleted_at IS NULL
+			  AND brand_id = $3
 		)
-	`, folderID, tenantID).Scan(&exists); err != nil {
+	`, folderID, tenantID, brandID).Scan(&exists); err != nil {
 		return response.ErrInternal(50010, "query_failed", "failed to validate image folder")
 	}
 	if !exists {
diff --git a/server/internal/tenant/app/template_service.go b/server/internal/tenant/app/template_service.go
index 0746b6c..5f3a562 100644
--- a/server/internal/tenant/app/template_service.go
+++ b/server/internal/tenant/app/template_service.go
@@ -490,6 +490,7 @@ func (s *TemplateService) executeGeneration(ctx context.Context, job generationJ
 		knowledgeContext, resolveErr := s.knowledge.ResolveContext(
 			ctx,
 			job.TenantID,
+			int64(extractInt(job.Params, "brand_id")),
 			knowledgeGroupIDs,
 			buildGenerationKnowledgeQuery(job.TemplateKey, job.TemplateName, job.Params),
 		)
diff --git a/server/internal/tenant/repository/generated/image.sql.go b/server/internal/tenant/repository/generated/image.sql.go
index 70db33d..f2640d4 100644
--- a/server/internal/tenant/repository/generated/image.sql.go
+++ b/server/internal/tenant/repository/generated/image.sql.go
@@ -15,24 +15,31 @@ const countImageAssets = `-- name: CountImageAssets :one
 SELECT COUNT(*)::INT AS total
 FROM image_assets
 WHERE tenant_id = $1
+  AND brand_id = $2
   AND status = 'active'
   AND deleted_at IS NULL
   AND (
-    $2::BIGINT IS NULL
-    OR ($2::BIGINT = 0 AND folder_id IS NULL)
-    OR folder_id = $2::BIGINT
+    $3::BIGINT IS NULL
+    OR ($3::BIGINT = 0 AND folder_id IS NULL)
+    OR folder_id = $3::BIGINT
   )
-  AND ($3::TEXT IS NULL OR name ILIKE '%' || $3::TEXT || '%')
+  AND ($4::TEXT IS NULL OR name ILIKE '%' || $4::TEXT || '%')
 `
 
 type CountImageAssetsParams struct {
 	TenantID    int64       `json:"tenant_id"`
+	BrandID     int64       `json:"brand_id"`
 	FolderID    pgtype.Int8 `json:"folder_id"`
 	SearchQuery pgtype.Text `json:"search_query"`
 }
 
 func (q *Queries) CountImageAssets(ctx context.Context, arg CountImageAssetsParams) (int32, error) {
-	row := q.db.QueryRow(ctx, countImageAssets, arg.TenantID, arg.FolderID, arg.SearchQuery)
+	row := q.db.QueryRow(ctx, countImageAssets,
+		arg.TenantID,
+		arg.BrandID,
+		arg.FolderID,
+		arg.SearchQuery,
+	)
 	var total int32
 	err := row.Scan(&total)
 	return total, err
@@ -42,32 +49,42 @@ const countUncategorizedImages = `-- name: CountUncategorizedImages :one
 SELECT COUNT(*)::INT AS count
 FROM image_assets
 WHERE tenant_id = $1
+  AND brand_id = $2
   AND folder_id IS NULL
   AND status = 'active'
   AND deleted_at IS NULL
 `
 
-func (q *Queries) CountUncategorizedImages(ctx context.Context, tenantID int64) (int32, error) {
-	row := q.db.QueryRow(ctx, countUncategorizedImages, tenantID)
+type CountUncategorizedImagesParams struct {
+	TenantID int64 `json:"tenant_id"`
+	BrandID  int64 `json:"brand_id"`
+}
+
+func (q *Queries) CountUncategorizedImages(ctx context.Context, arg CountUncategorizedImagesParams) (int32, error) {
+	row := q.db.QueryRow(ctx, countUncategorizedImages, arg.TenantID, arg.BrandID)
 	var count int32
 	err := row.Scan(&count)
 	return count, err
 }
 
 const getImageAsset = `-- name: GetImageAsset :one
-SELECT id, tenant_id, folder_id, object_key, name, size_bytes, status, created_by, created_at, updated_at
+SELECT id, tenant_id, brand_id, folder_id, object_key, name, size_bytes, status, created_by, created_at, updated_at
 FROM image_assets
-WHERE id = $1 AND tenant_id = $2
+WHERE id = $1
+  AND tenant_id = $2
+  AND brand_id = $3
 `
 
 type GetImageAssetParams struct {
 	ID       int64 `json:"id"`
 	TenantID int64 `json:"tenant_id"`
+	BrandID  int64 `json:"brand_id"`
 }
 
 type GetImageAssetRow struct {
 	ID        int64              `json:"id"`
 	TenantID  int64              `json:"tenant_id"`
+	BrandID   int64              `json:"brand_id"`
 	FolderID  pgtype.Int8        `json:"folder_id"`
 	ObjectKey string             `json:"object_key"`
 	Name      string             `json:"name"`
@@ -79,11 +96,12 @@ type GetImageAssetRow struct {
 }
 
 func (q *Queries) GetImageAsset(ctx context.Context, arg GetImageAssetParams) (GetImageAssetRow, error) {
-	row := q.db.QueryRow(ctx, getImageAsset, arg.ID, arg.TenantID)
+	row := q.db.QueryRow(ctx, getImageAsset, arg.ID, arg.TenantID, arg.BrandID)
 	var i GetImageAssetRow
 	err := row.Scan(
 		&i.ID,
 		&i.TenantID,
+		&i.BrandID,
 		&i.FolderID,
 		&i.ObjectKey,
 		&i.Name,
@@ -97,13 +115,14 @@ func (q *Queries) GetImageAsset(ctx context.Context, arg GetImageAssetParams) (G
 }
 
 const insertImageAsset = `-- name: InsertImageAsset :one
-INSERT INTO image_assets (tenant_id, folder_id, object_key, name, size_bytes, status, created_by)
-VALUES ($1, $2, $3, $4, $5, $6, $7)
+INSERT INTO image_assets (tenant_id, brand_id, folder_id, object_key, name, size_bytes, status, created_by)
+VALUES ($1, $2, $3, $4, $5, $6, $7, $8)
 RETURNING id
 `
 
 type InsertImageAssetParams struct {
 	TenantID  int64       `json:"tenant_id"`
+	BrandID   int64       `json:"brand_id"`
 	FolderID  pgtype.Int8 `json:"folder_id"`
 	ObjectKey string      `json:"object_key"`
 	Name      string      `json:"name"`
@@ -115,6 +134,7 @@ type InsertImageAssetParams struct {
 func (q *Queries) InsertImageAsset(ctx context.Context, arg InsertImageAssetParams) (int64, error) {
 	row := q.db.QueryRow(ctx, insertImageAsset,
 		arg.TenantID,
+		arg.BrandID,
 		arg.FolderID,
 		arg.ObjectKey,
 		arg.Name,
@@ -131,13 +151,15 @@ const listActiveImagesByFolder = `-- name: ListActiveImagesByFolder :many
 SELECT id, object_key, size_bytes
 FROM image_assets
 WHERE tenant_id = $1
-  AND folder_id = $2
+  AND brand_id = $2
+  AND folder_id = $3
   AND status = 'active'
   AND deleted_at IS NULL
 `
 
 type ListActiveImagesByFolderParams struct {
 	TenantID int64       `json:"tenant_id"`
+	BrandID  int64       `json:"brand_id"`
 	FolderID pgtype.Int8 `json:"folder_id"`
 }
 
@@ -148,7 +170,7 @@ type ListActiveImagesByFolderRow struct {
 }
 
 func (q *Queries) ListActiveImagesByFolder(ctx context.Context, arg ListActiveImagesByFolderParams) ([]ListActiveImagesByFolderRow, error) {
-	rows, err := q.db.Query(ctx, listActiveImagesByFolder, arg.TenantID, arg.FolderID)
+	rows, err := q.db.Query(ctx, listActiveImagesByFolder, arg.TenantID, arg.BrandID, arg.FolderID)
 	if err != nil {
 		return nil, err
 	}
@@ -168,23 +190,25 @@ func (q *Queries) ListActiveImagesByFolder(ctx context.Context, arg ListActiveIm
 }
 
 const listImageAssets = `-- name: ListImageAssets :many
-SELECT id, tenant_id, folder_id, object_key, name, size_bytes, status, created_by, created_at, updated_at
+SELECT id, tenant_id, brand_id, folder_id, object_key, name, size_bytes, status, created_by, created_at, updated_at
 FROM image_assets
 WHERE tenant_id = $1
+  AND brand_id = $2
   AND status = 'active'
   AND deleted_at IS NULL
   AND (
-    $2::BIGINT IS NULL
-    OR ($2::BIGINT = 0 AND folder_id IS NULL)
-    OR folder_id = $2::BIGINT
+    $3::BIGINT IS NULL
+    OR ($3::BIGINT = 0 AND folder_id IS NULL)
+    OR folder_id = $3::BIGINT
   )
-  AND ($3::TEXT IS NULL OR name ILIKE '%' || $3::TEXT || '%')
+  AND ($4::TEXT IS NULL OR name ILIKE '%' || $4::TEXT || '%')
 ORDER BY created_at DESC
-LIMIT $5 OFFSET $4
+LIMIT $6 OFFSET $5
 `
 
 type ListImageAssetsParams struct {
 	TenantID    int64       `json:"tenant_id"`
+	BrandID     int64       `json:"brand_id"`
 	FolderID    pgtype.Int8 `json:"folder_id"`
 	SearchQuery pgtype.Text `json:"search_query"`
 	PageOffset  int32       `json:"page_offset"`
@@ -194,6 +218,7 @@ type ListImageAssetsParams struct {
 type ListImageAssetsRow struct {
 	ID        int64              `json:"id"`
 	TenantID  int64              `json:"tenant_id"`
+	BrandID   int64              `json:"brand_id"`
 	FolderID  pgtype.Int8        `json:"folder_id"`
 	ObjectKey string             `json:"object_key"`
 	Name      string             `json:"name"`
@@ -207,6 +232,7 @@ type ListImageAssetsRow struct {
 func (q *Queries) ListImageAssets(ctx context.Context, arg ListImageAssetsParams) ([]ListImageAssetsRow, error) {
 	rows, err := q.db.Query(ctx, listImageAssets,
 		arg.TenantID,
+		arg.BrandID,
 		arg.FolderID,
 		arg.SearchQuery,
 		arg.PageOffset,
@@ -222,6 +248,7 @@ func (q *Queries) ListImageAssets(ctx context.Context, arg ListImageAssetsParams
 		if err := rows.Scan(
 			&i.ID,
 			&i.TenantID,
+			&i.BrandID,
 			&i.FolderID,
 			&i.ObjectKey,
 			&i.Name,
@@ -245,84 +272,113 @@ const markImagesInFolderPendingDelete = `-- name: MarkImagesInFolderPendingDelet
 UPDATE image_assets
 SET status = 'pending_delete', folder_id = NULL, updated_at = NOW()
 WHERE tenant_id = $1
-  AND folder_id = $2
+  AND brand_id = $2
+  AND folder_id = $3
   AND status = 'active'
   AND deleted_at IS NULL
 `
 
 type MarkImagesInFolderPendingDeleteParams struct {
 	TenantID int64       `json:"tenant_id"`
+	BrandID  int64       `json:"brand_id"`
 	FolderID pgtype.Int8 `json:"folder_id"`
 }
 
 func (q *Queries) MarkImagesInFolderPendingDelete(ctx context.Context, arg MarkImagesInFolderPendingDeleteParams) error {
-	_, err := q.db.Exec(ctx, markImagesInFolderPendingDelete, arg.TenantID, arg.FolderID)
+	_, err := q.db.Exec(ctx, markImagesInFolderPendingDelete, arg.TenantID, arg.BrandID, arg.FolderID)
 	return err
 }
 
 const updateImageAssetDeleted = `-- name: UpdateImageAssetDeleted :exec
 UPDATE image_assets
 SET status = 'deleted', deleted_at = NOW(), updated_at = NOW()
-WHERE id = $1 AND tenant_id = $2
+WHERE id = $1
+  AND tenant_id = $2
+  AND brand_id = $3
 `
 
 type UpdateImageAssetDeletedParams struct {
 	ID       int64 `json:"id"`
 	TenantID int64 `json:"tenant_id"`
+	BrandID  int64 `json:"brand_id"`
 }
 
 func (q *Queries) UpdateImageAssetDeleted(ctx context.Context, arg UpdateImageAssetDeletedParams) error {
-	_, err := q.db.Exec(ctx, updateImageAssetDeleted, arg.ID, arg.TenantID)
+	_, err := q.db.Exec(ctx, updateImageAssetDeleted, arg.ID, arg.TenantID, arg.BrandID)
 	return err
 }
 
 const updateImageAssetFolder = `-- name: UpdateImageAssetFolder :exec
 UPDATE image_assets
 SET folder_id = $1, updated_at = NOW()
-WHERE id = $2 AND tenant_id = $3
+WHERE id = $2
+  AND tenant_id = $3
+  AND brand_id = $4
 `
 
 type UpdateImageAssetFolderParams struct {
 	FolderID pgtype.Int8 `json:"folder_id"`
 	ID       int64       `json:"id"`
 	TenantID int64       `json:"tenant_id"`
+	BrandID  int64       `json:"brand_id"`
 }
 
 func (q *Queries) UpdateImageAssetFolder(ctx context.Context, arg UpdateImageAssetFolderParams) error {
-	_, err := q.db.Exec(ctx, updateImageAssetFolder, arg.FolderID, arg.ID, arg.TenantID)
+	_, err := q.db.Exec(ctx, updateImageAssetFolder,
+		arg.FolderID,
+		arg.ID,
+		arg.TenantID,
+		arg.BrandID,
+	)
 	return err
 }
 
 const updateImageAssetName = `-- name: UpdateImageAssetName :exec
 UPDATE image_assets
 SET name = $1, updated_at = NOW()
-WHERE id = $2 AND tenant_id = $3
+WHERE id = $2
+  AND tenant_id = $3
+  AND brand_id = $4
 `
 
 type UpdateImageAssetNameParams struct {
 	Name     string `json:"name"`
 	ID       int64  `json:"id"`
 	TenantID int64  `json:"tenant_id"`
+	BrandID  int64  `json:"brand_id"`
 }
 
 func (q *Queries) UpdateImageAssetName(ctx context.Context, arg UpdateImageAssetNameParams) error {
-	_, err := q.db.Exec(ctx, updateImageAssetName, arg.Name, arg.ID, arg.TenantID)
+	_, err := q.db.Exec(ctx, updateImageAssetName,
+		arg.Name,
+		arg.ID,
+		arg.TenantID,
+		arg.BrandID,
+	)
 	return err
 }
 
 const updateImageAssetStatus = `-- name: UpdateImageAssetStatus :exec
 UPDATE image_assets
 SET status = $1, updated_at = NOW()
-WHERE id = $2 AND tenant_id = $3
+WHERE id = $2
+  AND tenant_id = $3
+  AND brand_id = $4
 `
 
 type UpdateImageAssetStatusParams struct {
 	Status   string `json:"status"`
 	ID       int64  `json:"id"`
 	TenantID int64  `json:"tenant_id"`
+	BrandID  int64  `json:"brand_id"`
 }
 
 func (q *Queries) UpdateImageAssetStatus(ctx context.Context, arg UpdateImageAssetStatusParams) error {
-	_, err := q.db.Exec(ctx, updateImageAssetStatus, arg.Status, arg.ID, arg.TenantID)
+	_, err := q.db.Exec(ctx, updateImageAssetStatus,
+		arg.Status,
+		arg.ID,
+		arg.TenantID,
+		arg.BrandID,
+	)
 	return err
 }
diff --git a/server/internal/tenant/repository/generated/image_folder.sql.go b/server/internal/tenant/repository/generated/image_folder.sql.go
index 43dab2a..12a83e6 100644
--- a/server/internal/tenant/repository/generated/image_folder.sql.go
+++ b/server/internal/tenant/repository/generated/image_folder.sql.go
@@ -15,36 +15,39 @@ const countActiveImagesInFolder = `-- name: CountActiveImagesInFolder :one
 SELECT COUNT(*)::INT AS count
 FROM image_assets
 WHERE tenant_id = $1
-  AND folder_id = $2
+  AND brand_id = $2
+  AND folder_id = $3
   AND status = 'active'
   AND deleted_at IS NULL
 `
 
 type CountActiveImagesInFolderParams struct {
 	TenantID int64       `json:"tenant_id"`
+	BrandID  int64       `json:"brand_id"`
 	FolderID pgtype.Int8 `json:"folder_id"`
 }
 
 func (q *Queries) CountActiveImagesInFolder(ctx context.Context, arg CountActiveImagesInFolderParams) (int32, error) {
-	row := q.db.QueryRow(ctx, countActiveImagesInFolder, arg.TenantID, arg.FolderID)
+	row := q.db.QueryRow(ctx, countActiveImagesInFolder, arg.TenantID, arg.BrandID, arg.FolderID)
 	var count int32
 	err := row.Scan(&count)
 	return count, err
 }
 
 const createImageFolder = `-- name: CreateImageFolder :one
-INSERT INTO image_folders (tenant_id, name)
-VALUES ($1, $2)
+INSERT INTO image_folders (tenant_id, brand_id, name)
+VALUES ($1, $2, $3)
 RETURNING id
 `
 
 type CreateImageFolderParams struct {
 	TenantID int64  `json:"tenant_id"`
+	BrandID  int64  `json:"brand_id"`
 	Name     string `json:"name"`
 }
 
 func (q *Queries) CreateImageFolder(ctx context.Context, arg CreateImageFolderParams) (int64, error) {
-	row := q.db.QueryRow(ctx, createImageFolder, arg.TenantID, arg.Name)
+	row := q.db.QueryRow(ctx, createImageFolder, arg.TenantID, arg.BrandID, arg.Name)
 	var id int64
 	err := row.Scan(&id)
 	return id, err
@@ -52,44 +55,52 @@ func (q *Queries) CreateImageFolder(ctx context.Context, arg CreateImageFolderPa
 
 const deleteImageFolder = `-- name: DeleteImageFolder :exec
 DELETE FROM image_folders
-WHERE id = $1 AND tenant_id = $2
+WHERE id = $1
+  AND tenant_id = $2
+  AND brand_id = $3
 `
 
 type DeleteImageFolderParams struct {
 	ID       int64 `json:"id"`
 	TenantID int64 `json:"tenant_id"`
+	BrandID  int64 `json:"brand_id"`
 }
 
 func (q *Queries) DeleteImageFolder(ctx context.Context, arg DeleteImageFolderParams) error {
-	_, err := q.db.Exec(ctx, deleteImageFolder, arg.ID, arg.TenantID)
+	_, err := q.db.Exec(ctx, deleteImageFolder, arg.ID, arg.TenantID, arg.BrandID)
 	return err
 }
 
 const getImageFolder = `-- name: GetImageFolder :one
-SELECT id, tenant_id, name, created_at, updated_at
+SELECT id, tenant_id, brand_id, name, created_at, updated_at
 FROM image_folders
-WHERE id = $1 AND tenant_id = $2
+WHERE id = $1
+  AND tenant_id = $2
+  AND brand_id = $3
 `
 
 type GetImageFolderParams struct {
 	ID       int64 `json:"id"`
 	TenantID int64 `json:"tenant_id"`
+	BrandID  int64 `json:"brand_id"`
 }
 
 type GetImageFolderRow struct {
 	ID        int64              `json:"id"`
 	TenantID  int64              `json:"tenant_id"`
+	BrandID   int64              `json:"brand_id"`
 	Name      string             `json:"name"`
 	CreatedAt pgtype.Timestamptz `json:"created_at"`
 	UpdatedAt pgtype.Timestamptz `json:"updated_at"`
 }
 
 func (q *Queries) GetImageFolder(ctx context.Context, arg GetImageFolderParams) (GetImageFolderRow, error) {
-	row := q.db.QueryRow(ctx, getImageFolder, arg.ID, arg.TenantID)
+	row := q.db.QueryRow(ctx, getImageFolder, arg.ID, arg.TenantID, arg.BrandID)
 	var i GetImageFolderRow
 	err := row.Scan(
 		&i.ID,
 		&i.TenantID,
+		&i.BrandID,
 		&i.Name,
 		&i.CreatedAt,
 		&i.UpdatedAt,
@@ -98,26 +109,33 @@ func (q *Queries) GetImageFolder(ctx context.Context, arg GetImageFolderParams)
 }
 
 const listImageFolders = `-- name: ListImageFolders :many
-SELECT f.id, f.tenant_id, f.name, f.created_at, f.updated_at,
+SELECT f.id, f.tenant_id, f.brand_id, f.name, f.created_at, f.updated_at,
        COUNT(ia.id) FILTER (WHERE ia.status = 'active' AND ia.deleted_at IS NULL)::INT AS image_count
 FROM image_folders f
-LEFT JOIN image_assets ia ON ia.tenant_id = f.tenant_id AND ia.folder_id = f.id
+LEFT JOIN image_assets ia ON ia.tenant_id = f.tenant_id AND ia.brand_id = f.brand_id AND ia.folder_id = f.id
 WHERE f.tenant_id = $1
+  AND f.brand_id = $2
 GROUP BY f.id
 ORDER BY f.name
 `
 
+type ListImageFoldersParams struct {
+	TenantID int64 `json:"tenant_id"`
+	BrandID  int64 `json:"brand_id"`
+}
+
 type ListImageFoldersRow struct {
 	ID         int64              `json:"id"`
 	TenantID   int64              `json:"tenant_id"`
+	BrandID    int64              `json:"brand_id"`
 	Name       string             `json:"name"`
 	CreatedAt  pgtype.Timestamptz `json:"created_at"`
 	UpdatedAt  pgtype.Timestamptz `json:"updated_at"`
 	ImageCount int32              `json:"image_count"`
 }
 
-func (q *Queries) ListImageFolders(ctx context.Context, tenantID int64) ([]ListImageFoldersRow, error) {
-	rows, err := q.db.Query(ctx, listImageFolders, tenantID)
+func (q *Queries) ListImageFolders(ctx context.Context, arg ListImageFoldersParams) ([]ListImageFoldersRow, error) {
+	rows, err := q.db.Query(ctx, listImageFolders, arg.TenantID, arg.BrandID)
 	if err != nil {
 		return nil, err
 	}
@@ -128,6 +146,7 @@ func (q *Queries) ListImageFolders(ctx context.Context, tenantID int64) ([]ListI
 		if err := rows.Scan(
 			&i.ID,
 			&i.TenantID,
+			&i.BrandID,
 			&i.Name,
 			&i.CreatedAt,
 			&i.UpdatedAt,
@@ -146,16 +165,24 @@ func (q *Queries) ListImageFolders(ctx context.Context, tenantID int64) ([]ListI
 const updateImageFolder = `-- name: UpdateImageFolder :exec
 UPDATE image_folders
 SET name = $1, updated_at = NOW()
-WHERE id = $2 AND tenant_id = $3
+WHERE id = $2
+  AND tenant_id = $3
+  AND brand_id = $4
 `
 
 type UpdateImageFolderParams struct {
 	Name     string `json:"name"`
 	ID       int64  `json:"id"`
 	TenantID int64  `json:"tenant_id"`
+	BrandID  int64  `json:"brand_id"`
 }
 
 func (q *Queries) UpdateImageFolder(ctx context.Context, arg UpdateImageFolderParams) error {
-	_, err := q.db.Exec(ctx, updateImageFolder, arg.Name, arg.ID, arg.TenantID)
+	_, err := q.db.Exec(ctx, updateImageFolder,
+		arg.Name,
+		arg.ID,
+		arg.TenantID,
+		arg.BrandID,
+	)
 	return err
 }
diff --git a/server/internal/tenant/repository/generated/models.go b/server/internal/tenant/repository/generated/models.go
index 4c4174c..86329e5 100644
--- a/server/internal/tenant/repository/generated/models.go
+++ b/server/internal/tenant/repository/generated/models.go
@@ -460,6 +460,7 @@ type ImageAsset struct {
 	CreatedAt   pgtype.Timestamptz `json:"created_at"`
 	DeletedAt   pgtype.Timestamptz `json:"deleted_at"`
 	ContentHash pgtype.Text        `json:"content_hash"`
+	BrandID     int64              `json:"brand_id"`
 }
 
 type ImageAssetReference struct {
@@ -478,6 +479,7 @@ type ImageFolder struct {
 	Name      string             `json:"name"`
 	UpdatedAt pgtype.Timestamptz `json:"updated_at"`
 	CreatedAt pgtype.Timestamptz `json:"created_at"`
+	BrandID   int64              `json:"brand_id"`
 }
 
 type KnowledgeChunksMetum struct {
@@ -517,6 +519,7 @@ type KnowledgeGroup struct {
 	CreatedAt pgtype.Timestamptz `json:"created_at"`
 	UpdatedAt pgtype.Timestamptz `json:"updated_at"`
 	DeletedAt pgtype.Timestamptz `json:"deleted_at"`
+	BrandID   int64              `json:"brand_id"`
 }
 
 type KnowledgeItem struct {
@@ -536,6 +539,7 @@ type KnowledgeItem struct {
 	UpdatedAt       pgtype.Timestamptz `json:"updated_at"`
 	DeletedAt       pgtype.Timestamptz `json:"deleted_at"`
 	MarkdownContent pgtype.Text        `json:"markdown_content"`
+	BrandID         int64              `json:"brand_id"`
 }
 
 type KnowledgeParseTask struct {
diff --git a/server/internal/tenant/repository/generated/querier.go b/server/internal/tenant/repository/generated/querier.go
index 3e36542..0c4284b 100644
--- a/server/internal/tenant/repository/generated/querier.go
+++ b/server/internal/tenant/repository/generated/querier.go
@@ -28,7 +28,7 @@ type Querier interface {
 	CountPromptRulesUngrouped(ctx context.Context, arg CountPromptRulesUngroupedParams) (int64, error)
 	CountPublishedArticlesByTenantAndBrand(ctx context.Context, arg CountPublishedArticlesByTenantAndBrandParams) (int64, error)
 	CountScheduleTasks(ctx context.Context, arg CountScheduleTasksParams) (int64, error)
-	CountUncategorizedImages(ctx context.Context, tenantID int64) (int32, error)
+	CountUncategorizedImages(ctx context.Context, arg CountUncategorizedImagesParams) (int32, error)
 	CreateArticle(ctx context.Context, arg CreateArticleParams) (int64, error)
 	CreateArticleVersion(ctx context.Context, arg CreateArticleVersionParams) (int64, error)
 	CreateAuditLog(ctx context.Context, arg CreateAuditLogParams) error
@@ -121,7 +121,7 @@ type Querier interface {
 	ListDesktopClientsByUser(ctx context.Context, arg ListDesktopClientsByUserParams) ([]DesktopClient, error)
 	ListDesktopClientsByWorkspace(ctx context.Context, workspaceID int64) ([]DesktopClient, error)
 	ListImageAssets(ctx context.Context, arg ListImageAssetsParams) ([]ListImageAssetsRow, error)
-	ListImageFolders(ctx context.Context, tenantID int64) ([]ListImageFoldersRow, error)
+	ListImageFolders(ctx context.Context, arg ListImageFoldersParams) ([]ListImageFoldersRow, error)
 	ListImageReferenceArticles(ctx context.Context, arg ListImageReferenceArticlesParams) ([]ListImageReferenceArticlesRow, error)
 	ListImageReferences(ctx context.Context, arg ListImageReferencesParams) ([]ListImageReferencesRow, error)
 	ListKeywords(ctx context.Context, arg ListKeywordsParams) ([]ListKeywordsRow, error)
diff --git a/server/internal/tenant/repository/image_folder_repo.go b/server/internal/tenant/repository/image_folder_repo.go
index b02c4b9..d578d59 100644
--- a/server/internal/tenant/repository/image_folder_repo.go
+++ b/server/internal/tenant/repository/image_folder_repo.go
@@ -10,6 +10,7 @@ import (
 type ImageFolder struct {
 	ID         int64
 	TenantID   int64
+	BrandID    int64
 	Name       string
 	ImageCount int
 	CreatedAt  time.Time
@@ -17,12 +18,12 @@ type ImageFolder struct {
 }
 
 type ImageFolderRepository interface {
-	List(ctx context.Context, tenantID int64) ([]ImageFolder, error)
-	Get(ctx context.Context, tenantID, id int64) (*ImageFolder, error)
-	Create(ctx context.Context, tenantID int64, name string) (int64, error)
-	Update(ctx context.Context, tenantID, id int64, name string) error
-	Delete(ctx context.Context, tenantID, id int64) error
-	CountActiveImages(ctx context.Context, tenantID, folderID int64) (int, error)
+	List(ctx context.Context, tenantID, brandID int64) ([]ImageFolder, error)
+	Get(ctx context.Context, tenantID, brandID, id int64) (*ImageFolder, error)
+	Create(ctx context.Context, tenantID, brandID int64, name string) (int64, error)
+	Update(ctx context.Context, tenantID, brandID, id int64, name string) error
+	Delete(ctx context.Context, tenantID, brandID, id int64) error
+	CountActiveImages(ctx context.Context, tenantID, brandID, folderID int64) (int, error)
 }
 
 type imageFolderRepository struct {
@@ -33,8 +34,11 @@ func NewImageFolderRepository(db generated.DBTX) ImageFolderRepository {
 	return &imageFolderRepository{q: newQuerier(db)}
 }
 
-func (r *imageFolderRepository) List(ctx context.Context, tenantID int64) ([]ImageFolder, error) {
-	rows, err := r.q.ListImageFolders(ctx, tenantID)
+func (r *imageFolderRepository) List(ctx context.Context, tenantID, brandID int64) ([]ImageFolder, error) {
+	rows, err := r.q.ListImageFolders(ctx, generated.ListImageFoldersParams{
+		TenantID: tenantID,
+		BrandID:  brandID,
+	})
 	if err != nil {
 		return nil, err
 	}
@@ -44,6 +48,7 @@ func (r *imageFolderRepository) List(ctx context.Context, tenantID int64) ([]Ima
 		folders[i] = ImageFolder{
 			ID:         row.ID,
 			TenantID:   row.TenantID,
+			BrandID:    row.BrandID,
 			Name:       row.Name,
 			ImageCount: int(row.ImageCount),
 			CreatedAt:  timeFromTimestamp(row.CreatedAt),
@@ -53,10 +58,11 @@ func (r *imageFolderRepository) List(ctx context.Context, tenantID int64) ([]Ima
 	return folders, nil
 }
 
-func (r *imageFolderRepository) Get(ctx context.Context, tenantID, id int64) (*ImageFolder, error) {
+func (r *imageFolderRepository) Get(ctx context.Context, tenantID, brandID, id int64) (*ImageFolder, error) {
 	row, err := r.q.GetImageFolder(ctx, generated.GetImageFolderParams{
 		ID:       id,
 		TenantID: tenantID,
+		BrandID:  brandID,
 	})
 	if err != nil {
 		return nil, err
@@ -65,37 +71,42 @@ func (r *imageFolderRepository) Get(ctx context.Context, tenantID, id int64) (*I
 	return &ImageFolder{
 		ID:        row.ID,
 		TenantID:  row.TenantID,
+		BrandID:   row.BrandID,
 		Name:      row.Name,
 		CreatedAt: timeFromTimestamp(row.CreatedAt),
 		UpdatedAt: timeFromTimestamp(row.UpdatedAt),
 	}, nil
 }
 
-func (r *imageFolderRepository) Create(ctx context.Context, tenantID int64, name string) (int64, error) {
+func (r *imageFolderRepository) Create(ctx context.Context, tenantID, brandID int64, name string) (int64, error) {
 	return r.q.CreateImageFolder(ctx, generated.CreateImageFolderParams{
 		TenantID: tenantID,
+		BrandID:  brandID,
 		Name:     name,
 	})
 }
 
-func (r *imageFolderRepository) Update(ctx context.Context, tenantID, id int64, name string) error {
+func (r *imageFolderRepository) Update(ctx context.Context, tenantID, brandID, id int64, name string) error {
 	return r.q.UpdateImageFolder(ctx, generated.UpdateImageFolderParams{
 		Name:     name,
 		ID:       id,
 		TenantID: tenantID,
+		BrandID:  brandID,
 	})
 }
 
-func (r *imageFolderRepository) Delete(ctx context.Context, tenantID, id int64) error {
+func (r *imageFolderRepository) Delete(ctx context.Context, tenantID, brandID, id int64) error {
 	return r.q.DeleteImageFolder(ctx, generated.DeleteImageFolderParams{
 		ID:       id,
 		TenantID: tenantID,
+		BrandID:  brandID,
 	})
 }
 
-func (r *imageFolderRepository) CountActiveImages(ctx context.Context, tenantID, folderID int64) (int, error) {
+func (r *imageFolderRepository) CountActiveImages(ctx context.Context, tenantID, brandID, folderID int64) (int, error) {
 	count, err := r.q.CountActiveImagesInFolder(ctx, generated.CountActiveImagesInFolderParams{
 		TenantID: tenantID,
+		BrandID:  brandID,
 		FolderID: pgInt8(&folderID),
 	})
 	if err != nil {
diff --git a/server/internal/tenant/repository/image_repo.go b/server/internal/tenant/repository/image_repo.go
index 8933211..bfdb3cf 100644
--- a/server/internal/tenant/repository/image_repo.go
+++ b/server/internal/tenant/repository/image_repo.go
@@ -10,6 +10,7 @@ import (
 type ImageAsset struct {
 	ID        int64
 	TenantID  int64
+	BrandID   int64
 	FolderID  *int64
 	ObjectKey string
 	Name      string
@@ -22,6 +23,7 @@ type ImageAsset struct {
 
 type ImageAssetListParams struct {
 	TenantID    int64
+	BrandID     int64
 	FolderID    *int64
 	SearchQuery *string
 	PageSize    int
@@ -30,6 +32,7 @@ type ImageAssetListParams struct {
 
 type InsertImageAssetInput struct {
 	TenantID  int64
+	BrandID   int64
 	FolderID  *int64
 	ObjectKey string
 	Name      string
@@ -46,15 +49,15 @@ type FolderImageSummary struct {
 
 type ImageRepository interface {
 	List(ctx context.Context, params ImageAssetListParams) ([]ImageAsset, int, error)
-	Get(ctx context.Context, tenantID, id int64) (*ImageAsset, error)
+	Get(ctx context.Context, tenantID, brandID, id int64) (*ImageAsset, error)
 	Insert(ctx context.Context, input InsertImageAssetInput) (int64, error)
-	UpdateStatus(ctx context.Context, tenantID, id int64, status string) error
-	MarkDeleted(ctx context.Context, tenantID, id int64) error
-	UpdateName(ctx context.Context, tenantID, id int64, name string) error
-	UpdateFolder(ctx context.Context, tenantID, id int64, folderID *int64) error
-	ListActiveByFolder(ctx context.Context, tenantID, folderID int64) ([]FolderImageSummary, error)
-	MarkImagesInFolderPendingDelete(ctx context.Context, tenantID, folderID int64) error
-	CountUncategorized(ctx context.Context, tenantID int64) (int, error)
+	UpdateStatus(ctx context.Context, tenantID, brandID, id int64, status string) error
+	MarkDeleted(ctx context.Context, tenantID, brandID, id int64) error
+	UpdateName(ctx context.Context, tenantID, brandID, id int64, name string) error
+	UpdateFolder(ctx context.Context, tenantID, brandID, id int64, folderID *int64) error
+	ListActiveByFolder(ctx context.Context, tenantID, brandID, folderID int64) ([]FolderImageSummary, error)
+	MarkImagesInFolderPendingDelete(ctx context.Context, tenantID, brandID, folderID int64) error
+	CountUncategorized(ctx context.Context, tenantID, brandID int64) (int, error)
 }
 
 type imageRepository struct {
@@ -68,6 +71,7 @@ func NewImageRepository(db generated.DBTX) ImageRepository {
 func (r *imageRepository) List(ctx context.Context, params ImageAssetListParams) ([]ImageAsset, int, error) {
 	listParams := generated.ListImageAssetsParams{
 		TenantID:    params.TenantID,
+		BrandID:     params.BrandID,
 		FolderID:    pgInt8(params.FolderID),
 		PageOffset:  int32(params.PageOffset),
 		PageSize:    int32(params.PageSize),
@@ -81,6 +85,7 @@ func (r *imageRepository) List(ctx context.Context, params ImageAssetListParams)
 
 	total, err := r.q.CountImageAssets(ctx, generated.CountImageAssetsParams{
 		TenantID:    params.TenantID,
+		BrandID:     params.BrandID,
 		FolderID:    listParams.FolderID,
 		SearchQuery: listParams.SearchQuery,
 	})
@@ -93,6 +98,7 @@ func (r *imageRepository) List(ctx context.Context, params ImageAssetListParams)
 		assets[i] = ImageAsset{
 			ID:        row.ID,
 			TenantID:  row.TenantID,
+			BrandID:   row.BrandID,
 			FolderID:  nullableInt64(row.FolderID),
 			ObjectKey: row.ObjectKey,
 			Name:      row.Name,
@@ -107,10 +113,11 @@ func (r *imageRepository) List(ctx context.Context, params ImageAssetListParams)
 	return assets, int(total), nil
 }
 
-func (r *imageRepository) Get(ctx context.Context, tenantID, id int64) (*ImageAsset, error) {
+func (r *imageRepository) Get(ctx context.Context, tenantID, brandID, id int64) (*ImageAsset, error) {
 	row, err := r.q.GetImageAsset(ctx, generated.GetImageAssetParams{
 		ID:       id,
 		TenantID: tenantID,
+		BrandID:  brandID,
 	})
 	if err != nil {
 		return nil, err
@@ -119,6 +126,7 @@ func (r *imageRepository) Get(ctx context.Context, tenantID, id int64) (*ImageAs
 	return &ImageAsset{
 		ID:        row.ID,
 		TenantID:  row.TenantID,
+		BrandID:   row.BrandID,
 		FolderID:  nullableInt64(row.FolderID),
 		ObjectKey: row.ObjectKey,
 		Name:      row.Name,
@@ -133,6 +141,7 @@ func (r *imageRepository) Get(ctx context.Context, tenantID, id int64) (*ImageAs
 func (r *imageRepository) Insert(ctx context.Context, input InsertImageAssetInput) (int64, error) {
 	return r.q.InsertImageAsset(ctx, generated.InsertImageAssetParams{
 		TenantID:  input.TenantID,
+		BrandID:   input.BrandID,
 		FolderID:  pgInt8(input.FolderID),
 		ObjectKey: input.ObjectKey,
 		Name:      input.Name,
@@ -142,40 +151,45 @@ func (r *imageRepository) Insert(ctx context.Context, input InsertImageAssetInpu
 	})
 }
 
-func (r *imageRepository) UpdateStatus(ctx context.Context, tenantID, id int64, status string) error {
+func (r *imageRepository) UpdateStatus(ctx context.Context, tenantID, brandID, id int64, status string) error {
 	return r.q.UpdateImageAssetStatus(ctx, generated.UpdateImageAssetStatusParams{
 		Status:   status,
 		ID:       id,
 		TenantID: tenantID,
+		BrandID:  brandID,
 	})
 }
 
-func (r *imageRepository) MarkDeleted(ctx context.Context, tenantID, id int64) error {
+func (r *imageRepository) MarkDeleted(ctx context.Context, tenantID, brandID, id int64) error {
 	return r.q.UpdateImageAssetDeleted(ctx, generated.UpdateImageAssetDeletedParams{
 		ID:       id,
 		TenantID: tenantID,
+		BrandID:  brandID,
 	})
 }
 
-func (r *imageRepository) UpdateName(ctx context.Context, tenantID, id int64, name string) error {
+func (r *imageRepository) UpdateName(ctx context.Context, tenantID, brandID, id int64, name string) error {
 	return r.q.UpdateImageAssetName(ctx, generated.UpdateImageAssetNameParams{
 		Name:     name,
 		ID:       id,
 		TenantID: tenantID,
+		BrandID:  brandID,
 	})
 }
 
-func (r *imageRepository) UpdateFolder(ctx context.Context, tenantID, id int64, folderID *int64) error {
+func (r *imageRepository) UpdateFolder(ctx context.Context, tenantID, brandID, id int64, folderID *int64) error {
 	return r.q.UpdateImageAssetFolder(ctx, generated.UpdateImageAssetFolderParams{
 		FolderID: pgInt8(folderID),
 		ID:       id,
 		TenantID: tenantID,
+		BrandID:  brandID,
 	})
 }
 
-func (r *imageRepository) ListActiveByFolder(ctx context.Context, tenantID, folderID int64) ([]FolderImageSummary, error) {
+func (r *imageRepository) ListActiveByFolder(ctx context.Context, tenantID, brandID, folderID int64) ([]FolderImageSummary, error) {
 	rows, err := r.q.ListActiveImagesByFolder(ctx, generated.ListActiveImagesByFolderParams{
 		TenantID: tenantID,
+		BrandID:  brandID,
 		FolderID: pgInt8(&folderID),
 	})
 	if err != nil {
@@ -193,15 +207,19 @@ func (r *imageRepository) ListActiveByFolder(ctx context.Context, tenantID, fold
 	return result, nil
 }
 
-func (r *imageRepository) MarkImagesInFolderPendingDelete(ctx context.Context, tenantID, folderID int64) error {
+func (r *imageRepository) MarkImagesInFolderPendingDelete(ctx context.Context, tenantID, brandID, folderID int64) error {
 	return r.q.MarkImagesInFolderPendingDelete(ctx, generated.MarkImagesInFolderPendingDeleteParams{
 		TenantID: tenantID,
+		BrandID:  brandID,
 		FolderID: pgInt8(&folderID),
 	})
 }
 
-func (r *imageRepository) CountUncategorized(ctx context.Context, tenantID int64) (int, error) {
-	count, err := r.q.CountUncategorizedImages(ctx, tenantID)
+func (r *imageRepository) CountUncategorized(ctx context.Context, tenantID, brandID int64) (int, error) {
+	count, err := r.q.CountUncategorizedImages(ctx, generated.CountUncategorizedImagesParams{
+		TenantID: tenantID,
+		BrandID:  brandID,
+	})
 	if err != nil {
 		return 0, err
 	}
diff --git a/server/internal/tenant/repository/queries/image.sql b/server/internal/tenant/repository/queries/image.sql
index 99217b1..d8ee5ce 100644
--- a/server/internal/tenant/repository/queries/image.sql
+++ b/server/internal/tenant/repository/queries/image.sql
@@ -1,7 +1,8 @@
 -- name: ListImageAssets :many
-SELECT id, tenant_id, folder_id, object_key, name, size_bytes, status, created_by, created_at, updated_at
+SELECT id, tenant_id, brand_id, folder_id, object_key, name, size_bytes, status, created_by, created_at, updated_at
 FROM image_assets
 WHERE tenant_id = sqlc.arg(tenant_id)
+  AND brand_id = sqlc.arg(brand_id)
   AND status = 'active'
   AND deleted_at IS NULL
   AND (
@@ -17,6 +18,7 @@ LIMIT sqlc.arg(page_size) OFFSET sqlc.arg(page_offset);
 SELECT COUNT(*)::INT AS total
 FROM image_assets
 WHERE tenant_id = sqlc.arg(tenant_id)
+  AND brand_id = sqlc.arg(brand_id)
   AND status = 'active'
   AND deleted_at IS NULL
   AND (
@@ -27,39 +29,50 @@ WHERE tenant_id = sqlc.arg(tenant_id)
   AND (sqlc.narg(search_query)::TEXT IS NULL OR name ILIKE '%' || sqlc.narg(search_query)::TEXT || '%');
 
 -- name: GetImageAsset :one
-SELECT id, tenant_id, folder_id, object_key, name, size_bytes, status, created_by, created_at, updated_at
+SELECT id, tenant_id, brand_id, folder_id, object_key, name, size_bytes, status, created_by, created_at, updated_at
 FROM image_assets
-WHERE id = sqlc.arg(id) AND tenant_id = sqlc.arg(tenant_id);
+WHERE id = sqlc.arg(id)
+  AND tenant_id = sqlc.arg(tenant_id)
+  AND brand_id = sqlc.arg(brand_id);
 
 -- name: InsertImageAsset :one
-INSERT INTO image_assets (tenant_id, folder_id, object_key, name, size_bytes, status, created_by)
-VALUES (sqlc.arg(tenant_id), sqlc.narg(folder_id), sqlc.arg(object_key), sqlc.arg(name), sqlc.arg(size_bytes), sqlc.arg(status), sqlc.arg(created_by))
+INSERT INTO image_assets (tenant_id, brand_id, folder_id, object_key, name, size_bytes, status, created_by)
+VALUES (sqlc.arg(tenant_id), sqlc.arg(brand_id), sqlc.narg(folder_id), sqlc.arg(object_key), sqlc.arg(name), sqlc.arg(size_bytes), sqlc.arg(status), sqlc.arg(created_by))
 RETURNING id;
 
 -- name: UpdateImageAssetStatus :exec
 UPDATE image_assets
 SET status = sqlc.arg(status), updated_at = NOW()
-WHERE id = sqlc.arg(id) AND tenant_id = sqlc.arg(tenant_id);
+WHERE id = sqlc.arg(id)
+  AND tenant_id = sqlc.arg(tenant_id)
+  AND brand_id = sqlc.arg(brand_id);
 
 -- name: UpdateImageAssetDeleted :exec
 UPDATE image_assets
 SET status = 'deleted', deleted_at = NOW(), updated_at = NOW()
-WHERE id = sqlc.arg(id) AND tenant_id = sqlc.arg(tenant_id);
+WHERE id = sqlc.arg(id)
+  AND tenant_id = sqlc.arg(tenant_id)
+  AND brand_id = sqlc.arg(brand_id);
 
 -- name: UpdateImageAssetName :exec
 UPDATE image_assets
 SET name = sqlc.arg(name), updated_at = NOW()
-WHERE id = sqlc.arg(id) AND tenant_id = sqlc.arg(tenant_id);
+WHERE id = sqlc.arg(id)
+  AND tenant_id = sqlc.arg(tenant_id)
+  AND brand_id = sqlc.arg(brand_id);
 
 -- name: UpdateImageAssetFolder :exec
 UPDATE image_assets
 SET folder_id = sqlc.narg(folder_id), updated_at = NOW()
-WHERE id = sqlc.arg(id) AND tenant_id = sqlc.arg(tenant_id);
+WHERE id = sqlc.arg(id)
+  AND tenant_id = sqlc.arg(tenant_id)
+  AND brand_id = sqlc.arg(brand_id);
 
 -- name: ListActiveImagesByFolder :many
 SELECT id, object_key, size_bytes
 FROM image_assets
 WHERE tenant_id = sqlc.arg(tenant_id)
+  AND brand_id = sqlc.arg(brand_id)
   AND folder_id = sqlc.arg(folder_id)
   AND status = 'active'
   AND deleted_at IS NULL;
@@ -68,6 +81,7 @@ WHERE tenant_id = sqlc.arg(tenant_id)
 UPDATE image_assets
 SET status = 'pending_delete', folder_id = NULL, updated_at = NOW()
 WHERE tenant_id = sqlc.arg(tenant_id)
+  AND brand_id = sqlc.arg(brand_id)
   AND folder_id = sqlc.arg(folder_id)
   AND status = 'active'
   AND deleted_at IS NULL;
@@ -76,6 +90,7 @@ WHERE tenant_id = sqlc.arg(tenant_id)
 SELECT COUNT(*)::INT AS count
 FROM image_assets
 WHERE tenant_id = sqlc.arg(tenant_id)
+  AND brand_id = sqlc.arg(brand_id)
   AND folder_id IS NULL
   AND status = 'active'
   AND deleted_at IS NULL;
diff --git a/server/internal/tenant/repository/queries/image_folder.sql b/server/internal/tenant/repository/queries/image_folder.sql
index b0afb7c..a548aec 100644
--- a/server/internal/tenant/repository/queries/image_folder.sql
+++ b/server/internal/tenant/repository/queries/image_folder.sql
@@ -1,35 +1,43 @@
 -- name: ListImageFolders :many
-SELECT f.id, f.tenant_id, f.name, f.created_at, f.updated_at,
+SELECT f.id, f.tenant_id, f.brand_id, f.name, f.created_at, f.updated_at,
        COUNT(ia.id) FILTER (WHERE ia.status = 'active' AND ia.deleted_at IS NULL)::INT AS image_count
 FROM image_folders f
-LEFT JOIN image_assets ia ON ia.tenant_id = f.tenant_id AND ia.folder_id = f.id
+LEFT JOIN image_assets ia ON ia.tenant_id = f.tenant_id AND ia.brand_id = f.brand_id AND ia.folder_id = f.id
 WHERE f.tenant_id = sqlc.arg(tenant_id)
+  AND f.brand_id = sqlc.arg(brand_id)
 GROUP BY f.id
 ORDER BY f.name;
 
 -- name: CreateImageFolder :one
-INSERT INTO image_folders (tenant_id, name)
-VALUES (sqlc.arg(tenant_id), sqlc.arg(name))
+INSERT INTO image_folders (tenant_id, brand_id, name)
+VALUES (sqlc.arg(tenant_id), sqlc.arg(brand_id), sqlc.arg(name))
 RETURNING id;
 
 -- name: UpdateImageFolder :exec
 UPDATE image_folders
 SET name = sqlc.arg(name), updated_at = NOW()
-WHERE id = sqlc.arg(id) AND tenant_id = sqlc.arg(tenant_id);
+WHERE id = sqlc.arg(id)
+  AND tenant_id = sqlc.arg(tenant_id)
+  AND brand_id = sqlc.arg(brand_id);
 
 -- name: GetImageFolder :one
-SELECT id, tenant_id, name, created_at, updated_at
+SELECT id, tenant_id, brand_id, name, created_at, updated_at
 FROM image_folders
-WHERE id = sqlc.arg(id) AND tenant_id = sqlc.arg(tenant_id);
+WHERE id = sqlc.arg(id)
+  AND tenant_id = sqlc.arg(tenant_id)
+  AND brand_id = sqlc.arg(brand_id);
 
 -- name: DeleteImageFolder :exec
 DELETE FROM image_folders
-WHERE id = sqlc.arg(id) AND tenant_id = sqlc.arg(tenant_id);
+WHERE id = sqlc.arg(id)
+  AND tenant_id = sqlc.arg(tenant_id)
+  AND brand_id = sqlc.arg(brand_id);
 
 -- name: CountActiveImagesInFolder :one
 SELECT COUNT(*)::INT AS count
 FROM image_assets
 WHERE tenant_id = sqlc.arg(tenant_id)
+  AND brand_id = sqlc.arg(brand_id)
   AND folder_id = sqlc.arg(folder_id)
   AND status = 'active'
   AND deleted_at IS NULL;
diff --git a/server/internal/tenant/transport/router.go b/server/internal/tenant/transport/router.go
index 52c8570..612bcea 100644
--- a/server/internal/tenant/transport/router.go
+++ b/server/internal/tenant/transport/router.go
@@ -268,6 +268,7 @@ func RegisterRoutes(app *bootstrap.App) {
 	monitoring.POST("/brands/:brand_id/collect-now", monitoringHandler.CollectNow)
 
 	knowledge := tenantProtected.Group("/knowledge")
+	knowledge.Use(middleware.RequireCurrentBrand())
 	knowledgeHandler := NewKnowledgeHandler(app)
 	knowledge.GET("/groups", knowledgeHandler.ListGroups)
 	knowledge.POST("/groups", knowledgeHandler.CreateGroup)
@@ -315,14 +316,16 @@ func RegisterRoutes(app *bootstrap.App) {
 
 	images := tenantProtected.Group("/images")
 	imgHandler := NewImageHandler(app)
+	images.GET("/storage-usage", imgHandler.StorageUsage)
+	images.Use(middleware.RequireCurrentBrand())
 	images.GET("", imgHandler.ListImages)
 	images.POST("", imgHandler.UploadImage)
 	images.PUT("/:id", imgHandler.UpdateImage)
 	images.GET("/:id/references", imgHandler.GetImageReferences)
 	images.DELETE("/:id", imgHandler.DeleteImage)
-	images.GET("/storage-usage", imgHandler.StorageUsage)
 
 	imageFolders := tenantProtected.Group("/images/folders")
+	imageFolders.Use(middleware.RequireCurrentBrand())
 	imageFolders.GET("", imgHandler.ListFolders)
 	imageFolders.POST("", imgHandler.CreateFolder)
 	imageFolders.PUT("/:id", imgHandler.UpdateFolder)
diff --git a/server/internal/worker/generate/kol_generation_worker.go b/server/internal/worker/generate/kol_generation_worker.go
index 5a9a76c..bb55a0e 100644
--- a/server/internal/worker/generate/kol_generation_worker.go
+++ b/server/internal/worker/generate/kol_generation_worker.go
@@ -125,6 +125,7 @@ func (w *KolGenerationWorker) Process(ctx context.Context, task tenantapp.Claime
 		knowledgeContext, err := w.knowledge.ResolveContext(
 			ctx,
 			task.TenantID,
+			int64(kolIntInput(task.InputParams, "brand_id")),
 			knowledgeGroupIDs,
 			buildKolKnowledgeQuery(task.InputParams),
 		)
diff --git a/server/migrations/20260630110000_scope_knowledge_and_images_to_brand.down.sql b/server/migrations/20260630110000_scope_knowledge_and_images_to_brand.down.sql
new file mode 100644
index 0000000..b299645
--- /dev/null
+++ b/server/migrations/20260630110000_scope_knowledge_and_images_to_brand.down.sql
@@ -0,0 +1,71 @@
+ALTER TABLE image_assets
+    DROP CONSTRAINT IF EXISTS fk_image_assets_folder_brand;
+
+ALTER TABLE image_folders
+    DROP CONSTRAINT IF EXISTS uq_image_folders_tenant_brand_name;
+
+ALTER TABLE image_folders
+    DROP CONSTRAINT IF EXISTS uq_image_folders_tenant_brand_id;
+
+DROP INDEX IF EXISTS idx_image_folders_tenant_brand;
+DROP INDEX IF EXISTS idx_image_assets_tenant_brand_folder;
+DROP INDEX IF EXISTS idx_image_assets_tenant_brand_created;
+DROP INDEX IF EXISTS idx_image_assets_tenant_brand_status;
+
+ALTER TABLE image_assets
+    DROP COLUMN IF EXISTS brand_id;
+
+ALTER TABLE image_folders
+    DROP COLUMN IF EXISTS brand_id;
+
+ALTER TABLE image_folders
+    ADD CONSTRAINT uq_image_folders_tenant_name UNIQUE (tenant_id, name);
+
+ALTER TABLE image_folders
+    ADD CONSTRAINT uq_image_folders_tenant_id UNIQUE (tenant_id, id);
+
+ALTER TABLE image_assets
+    ADD CONSTRAINT fk_image_assets_folder
+    FOREIGN KEY (tenant_id, folder_id)
+    REFERENCES image_folders(tenant_id, id);
+
+CREATE INDEX IF NOT EXISTS idx_image_folders_tenant ON image_folders (tenant_id);
+CREATE INDEX IF NOT EXISTS idx_image_assets_tenant_folder
+    ON image_assets (tenant_id, folder_id)
+    WHERE status = 'active' AND deleted_at IS NULL;
+CREATE INDEX IF NOT EXISTS idx_image_assets_tenant_created
+    ON image_assets (tenant_id, created_at DESC)
+    WHERE status = 'active' AND deleted_at IS NULL;
+CREATE INDEX IF NOT EXISTS idx_image_assets_tenant_status
+    ON image_assets (tenant_id, status, created_at DESC);
+
+ALTER TABLE knowledge_groups
+    DROP CONSTRAINT IF EXISTS fk_knowledge_groups_parent_brand;
+
+ALTER TABLE knowledge_items
+    DROP CONSTRAINT IF EXISTS fk_knowledge_items_group_brand;
+
+ALTER TABLE knowledge_groups
+    DROP CONSTRAINT IF EXISTS uq_knowledge_groups_tenant_brand_id;
+
+DROP INDEX IF EXISTS uk_knowledge_group_brand_name;
+DROP INDEX IF EXISTS idx_knowledge_group_tenant_brand_parent;
+DROP INDEX IF EXISTS idx_knowledge_item_tenant_brand_group_status;
+
+ALTER TABLE knowledge_items
+    DROP COLUMN IF EXISTS brand_id;
+
+ALTER TABLE knowledge_groups
+    DROP COLUMN IF EXISTS brand_id;
+
+CREATE UNIQUE INDEX IF NOT EXISTS uk_knowledge_group_name
+    ON knowledge_groups(tenant_id, COALESCE(parent_id, 0), name)
+    WHERE deleted_at IS NULL;
+
+CREATE INDEX IF NOT EXISTS idx_knowledge_group_tenant_parent
+    ON knowledge_groups(tenant_id, parent_id, sort_order)
+    WHERE deleted_at IS NULL;
+
+CREATE INDEX IF NOT EXISTS idx_knowledge_item_group_status
+    ON knowledge_items(tenant_id, group_id, status)
+    WHERE deleted_at IS NULL;
diff --git a/server/migrations/20260630110000_scope_knowledge_and_images_to_brand.up.sql b/server/migrations/20260630110000_scope_knowledge_and_images_to_brand.up.sql
new file mode 100644
index 0000000..166dd88
--- /dev/null
+++ b/server/migrations/20260630110000_scope_knowledge_and_images_to_brand.up.sql
@@ -0,0 +1,282 @@
+ALTER TABLE knowledge_groups
+    ADD COLUMN IF NOT EXISTS brand_id BIGINT REFERENCES brands(id);
+
+ALTER TABLE knowledge_items
+    ADD COLUMN IF NOT EXISTS brand_id BIGINT REFERENCES brands(id);
+
+ALTER TABLE image_folders
+    ADD COLUMN IF NOT EXISTS brand_id BIGINT REFERENCES brands(id);
+
+ALTER TABLE image_assets
+    ADD COLUMN IF NOT EXISTS brand_id BIGINT REFERENCES brands(id);
+
+INSERT INTO brands (tenant_id, name, description, status)
+SELECT tenant_id, '未归属', '系统迁移生成，用于存放无法自动推断品牌的历史知识库和图片库资料。', 'active'
+FROM (
+    SELECT tenant_id FROM knowledge_groups WHERE brand_id IS NULL
+    UNION
+    SELECT tenant_id FROM knowledge_items WHERE brand_id IS NULL
+    UNION
+    SELECT tenant_id FROM image_folders WHERE brand_id IS NULL
+    UNION
+    SELECT tenant_id FROM image_assets WHERE brand_id IS NULL
+) tenants_with_assets
+WHERE NOT EXISTS (
+    SELECT 1
+    FROM brands b
+    WHERE b.tenant_id = tenants_with_assets.tenant_id
+      AND b.deleted_at IS NULL
+);
+
+WITH inferred_group_brand AS (
+    SELECT DISTINCT ON (prkg.knowledge_group_id)
+           prkg.knowledge_group_id,
+           pr.brand_id
+    FROM prompt_rule_knowledge_groups prkg
+    JOIN prompt_rules pr
+      ON pr.id = prkg.prompt_rule_id
+     AND pr.deleted_at IS NULL
+    JOIN knowledge_groups kg
+      ON kg.id = prkg.knowledge_group_id
+     AND kg.tenant_id = pr.tenant_id
+     AND kg.deleted_at IS NULL
+    WHERE pr.brand_id IS NOT NULL
+    ORDER BY prkg.knowledge_group_id, pr.updated_at DESC, pr.id DESC
+)
+UPDATE knowledge_groups kg
+SET brand_id = igb.brand_id,
+    updated_at = NOW()
+FROM inferred_group_brand igb
+WHERE kg.id = igb.knowledge_group_id
+  AND kg.brand_id IS NULL;
+
+UPDATE knowledge_groups child
+SET brand_id = parent.brand_id,
+    updated_at = NOW()
+FROM knowledge_groups parent
+WHERE child.parent_id = parent.id
+  AND child.tenant_id = parent.tenant_id
+  AND parent.brand_id IS NOT NULL;
+
+UPDATE knowledge_groups parent
+SET brand_id = child.brand_id,
+    updated_at = NOW()
+FROM knowledge_groups child
+WHERE child.parent_id = parent.id
+  AND child.tenant_id = parent.tenant_id
+  AND parent.brand_id IS NULL
+  AND child.brand_id IS NOT NULL;
+
+WITH fallback_brand AS (
+    SELECT DISTINCT ON (tenant_id) tenant_id, id AS brand_id
+    FROM brands
+    WHERE deleted_at IS NULL
+    ORDER BY tenant_id, created_at, id
+)
+UPDATE knowledge_groups kg
+SET brand_id = fb.brand_id,
+    updated_at = NOW()
+FROM fallback_brand fb
+WHERE kg.tenant_id = fb.tenant_id
+  AND kg.brand_id IS NULL;
+
+UPDATE knowledge_items ki
+SET brand_id = kg.brand_id,
+    updated_at = NOW()
+FROM knowledge_groups kg
+WHERE ki.group_id = kg.id
+  AND ki.tenant_id = kg.tenant_id
+  AND kg.brand_id IS NOT NULL;
+
+WITH inferred_asset_brand AS (
+    SELECT DISTINCT ON (r.image_asset_id)
+           r.image_asset_id,
+           a.brand_id
+    FROM image_asset_references r
+    JOIN articles a
+      ON a.id = r.article_id
+     AND a.tenant_id = r.tenant_id
+     AND a.deleted_at IS NULL
+    WHERE a.brand_id IS NOT NULL
+    ORDER BY r.image_asset_id, a.updated_at DESC, a.id DESC
+)
+UPDATE image_assets ia
+SET brand_id = iab.brand_id,
+    updated_at = NOW()
+FROM inferred_asset_brand iab
+WHERE ia.id = iab.image_asset_id
+  AND ia.brand_id IS NULL;
+
+WITH schedule_cover_asset_brand AS (
+    SELECT DISTINCT ON (cover_image_asset_id)
+           cover_image_asset_id AS image_asset_id,
+           brand_id
+    FROM schedule_tasks
+    WHERE cover_image_asset_id IS NOT NULL
+      AND brand_id IS NOT NULL
+      AND deleted_at IS NULL
+    ORDER BY cover_image_asset_id, updated_at DESC, id DESC
+)
+UPDATE image_assets ia
+SET brand_id = scab.brand_id,
+    updated_at = NOW()
+FROM schedule_cover_asset_brand scab
+WHERE ia.id = scab.image_asset_id
+  AND ia.tenant_id = (SELECT tenant_id FROM brands WHERE id = scab.brand_id)
+  AND ia.brand_id IS NULL;
+
+WITH schedule_folder_brand AS (
+    SELECT DISTINCT ON (cover_random_folder_id)
+           cover_random_folder_id AS folder_id,
+           brand_id
+    FROM schedule_tasks
+    WHERE cover_random_folder_id IS NOT NULL
+      AND brand_id IS NOT NULL
+      AND deleted_at IS NULL
+    ORDER BY cover_random_folder_id, updated_at DESC, id DESC
+)
+UPDATE image_folders f
+SET brand_id = sfb.brand_id,
+    updated_at = NOW()
+FROM schedule_folder_brand sfb
+WHERE f.id = sfb.folder_id
+  AND f.tenant_id = (SELECT tenant_id FROM brands WHERE id = sfb.brand_id)
+  AND f.brand_id IS NULL;
+
+WITH folder_brand_from_assets AS (
+    SELECT DISTINCT ON (folder_id)
+           folder_id,
+           brand_id
+    FROM image_assets
+    WHERE folder_id IS NOT NULL
+      AND brand_id IS NOT NULL
+    ORDER BY folder_id, updated_at DESC, id DESC
+)
+UPDATE image_folders f
+SET brand_id = fbfa.brand_id,
+    updated_at = NOW()
+FROM folder_brand_from_assets fbfa
+WHERE f.id = fbfa.folder_id
+  AND f.brand_id IS NULL;
+
+UPDATE image_assets ia
+SET brand_id = f.brand_id,
+    updated_at = NOW()
+FROM image_folders f
+WHERE ia.folder_id = f.id
+  AND ia.tenant_id = f.tenant_id
+  AND f.brand_id IS NOT NULL;
+
+WITH fallback_brand AS (
+    SELECT DISTINCT ON (tenant_id) tenant_id, id AS brand_id
+    FROM brands
+    WHERE deleted_at IS NULL
+    ORDER BY tenant_id, created_at, id
+)
+UPDATE image_folders f
+SET brand_id = fb.brand_id,
+    updated_at = NOW()
+FROM fallback_brand fb
+WHERE f.tenant_id = fb.tenant_id
+  AND f.brand_id IS NULL;
+
+UPDATE image_assets ia
+SET brand_id = f.brand_id,
+    updated_at = NOW()
+FROM image_folders f
+WHERE ia.folder_id = f.id
+  AND ia.tenant_id = f.tenant_id
+  AND f.brand_id IS NOT NULL;
+
+WITH fallback_brand AS (
+    SELECT DISTINCT ON (tenant_id) tenant_id, id AS brand_id
+    FROM brands
+    WHERE deleted_at IS NULL
+    ORDER BY tenant_id, created_at, id
+)
+UPDATE image_assets ia
+SET brand_id = fb.brand_id,
+    updated_at = NOW()
+FROM fallback_brand fb
+WHERE ia.tenant_id = fb.tenant_id
+  AND ia.brand_id IS NULL;
+
+ALTER TABLE knowledge_groups
+    ALTER COLUMN brand_id SET NOT NULL;
+
+ALTER TABLE knowledge_items
+    ALTER COLUMN brand_id SET NOT NULL;
+
+ALTER TABLE image_folders
+    ALTER COLUMN brand_id SET NOT NULL;
+
+ALTER TABLE image_assets
+    ALTER COLUMN brand_id SET NOT NULL;
+
+DROP INDEX IF EXISTS uk_knowledge_group_name;
+DROP INDEX IF EXISTS idx_knowledge_group_tenant_parent;
+DROP INDEX IF EXISTS idx_knowledge_item_group_status;
+
+CREATE UNIQUE INDEX IF NOT EXISTS uk_knowledge_group_brand_name
+    ON knowledge_groups(tenant_id, brand_id, COALESCE(parent_id, 0), name)
+    WHERE deleted_at IS NULL;
+
+CREATE INDEX IF NOT EXISTS idx_knowledge_group_tenant_brand_parent
+    ON knowledge_groups(tenant_id, brand_id, parent_id, sort_order)
+    WHERE deleted_at IS NULL;
+
+CREATE INDEX IF NOT EXISTS idx_knowledge_item_tenant_brand_group_status
+    ON knowledge_items(tenant_id, brand_id, group_id, status)
+    WHERE deleted_at IS NULL;
+
+ALTER TABLE knowledge_groups
+    ADD CONSTRAINT uq_knowledge_groups_tenant_brand_id UNIQUE (tenant_id, brand_id, id);
+
+ALTER TABLE knowledge_items
+    ADD CONSTRAINT fk_knowledge_items_group_brand
+    FOREIGN KEY (tenant_id, brand_id, group_id)
+    REFERENCES knowledge_groups(tenant_id, brand_id, id);
+
+ALTER TABLE knowledge_groups
+    ADD CONSTRAINT fk_knowledge_groups_parent_brand
+    FOREIGN KEY (tenant_id, brand_id, parent_id)
+    REFERENCES knowledge_groups(tenant_id, brand_id, id);
+
+ALTER TABLE image_assets
+    DROP CONSTRAINT IF EXISTS fk_image_assets_folder;
+
+ALTER TABLE image_folders
+    DROP CONSTRAINT IF EXISTS uq_image_folders_tenant_name;
+
+ALTER TABLE image_folders
+    DROP CONSTRAINT IF EXISTS uq_image_folders_tenant_id;
+
+ALTER TABLE image_folders
+    ADD CONSTRAINT uq_image_folders_tenant_brand_name UNIQUE (tenant_id, brand_id, name);
+
+ALTER TABLE image_folders
+    ADD CONSTRAINT uq_image_folders_tenant_brand_id UNIQUE (tenant_id, brand_id, id);
+
+ALTER TABLE image_assets
+    ADD CONSTRAINT fk_image_assets_folder_brand
+    FOREIGN KEY (tenant_id, brand_id, folder_id)
+    REFERENCES image_folders(tenant_id, brand_id, id);
+
+DROP INDEX IF EXISTS idx_image_folders_tenant;
+DROP INDEX IF EXISTS idx_image_assets_tenant_folder;
+DROP INDEX IF EXISTS idx_image_assets_tenant_created;
+DROP INDEX IF EXISTS idx_image_assets_tenant_status;
+
+CREATE INDEX IF NOT EXISTS idx_image_folders_tenant_brand
+    ON image_folders (tenant_id, brand_id);
+
+CREATE INDEX IF NOT EXISTS idx_image_assets_tenant_brand_folder
+    ON image_assets (tenant_id, brand_id, folder_id)
+    WHERE status = 'active' AND deleted_at IS NULL;
+
+CREATE INDEX IF NOT EXISTS idx_image_assets_tenant_brand_created
+    ON image_assets (tenant_id, brand_id, created_at DESC)
+    WHERE status = 'active' AND deleted_at IS NULL;
+
+CREATE INDEX IF NOT EXISTS idx_image_assets_tenant_brand_status
+    ON image_assets (tenant_id, brand_id, status, created_at DESC);