diff --git a/apps/backend/prisma/migrations/20260723083445_add_category_soft_delete/migration.sql b/apps/backend/prisma/migrations/20260723083445_add_category_soft_delete/migration.sql
new file mode 100644
index 0000000..4dd4f81
--- /dev/null
+++ b/apps/backend/prisma/migrations/20260723083445_add_category_soft_delete/migration.sql
@@ -0,0 +1,5 @@
+-- AlterTable
+ALTER TABLE "Category" ADD COLUMN     "deletedAt" TIMESTAMP(3);
+
+-- CreateIndex
+CREATE INDEX "Category_deletedAt_idx" ON "Category"("deletedAt");
diff --git a/apps/backend/prisma/schema.prisma b/apps/backend/prisma/schema.prisma
index e0487f5..2b82ed6 100644
--- a/apps/backend/prisma/schema.prisma
+++ b/apps/backend/prisma/schema.prisma
@@ -37,8 +37,11 @@ model Category {
   products     Product[]
   attributes   AttributeDefinition[]
   translations CategoryTranslation[]
+  deletedAt    DateTime?
   createdAt    DateTime              @default(now())
   updatedAt    DateTime              @updatedAt
+
+  @@index([deletedAt])
 }
 
 model CategoryTranslation {
diff --git a/apps/backend/src/routes/categories.ts b/apps/backend/src/routes/categories.ts
index 077c2c8..412cc9c 100644
--- a/apps/backend/src/routes/categories.ts
+++ b/apps/backend/src/routes/categories.ts
@@ -20,6 +20,7 @@ export const categoriesRoute = new Elysia({ prefix: "/categories" })
   .get("/", async ({ query }) => {
     const lang = (query as any).lang || 'th';
     const categories = await prisma.category.findMany({
+      where: { deletedAt: null },
       orderBy: { name: "asc" },
       include: {
         translations: true,
@@ -45,7 +46,7 @@ export const categoriesRoute = new Elysia({ prefix: "/categories" })
 
     const [category, total] = await Promise.all([
       prisma.category.findUnique({
-        where: { id },
+        where: { id, deletedAt: null },
         include: {
           translations: true,
           products: {
@@ -118,7 +119,7 @@ export const categoriesRoute = new Elysia({ prefix: "/categories" })
     if (isNaN(id)) return status(400, { message: "Invalid category ID" });
 
     try {
-      const categoryExists = await prisma.category.findUnique({ where: { id } });
+      const categoryExists = await prisma.category.findFirst({ where: { id, deletedAt: null } });
       if (!categoryExists) return status(404, { message: "Category not found" });
 
       const payload = body as any;
@@ -170,7 +171,7 @@ export const categoriesRoute = new Elysia({ prefix: "/categories" })
 
     try {
       const category = await prisma.category.update({
-        where: { id },
+        where: { id, deletedAt: null },
         data: {
           imageUrl: body.imageUrl,
         },
@@ -217,7 +218,7 @@ export const categoriesRoute = new Elysia({ prefix: "/categories" })
 
     try {
       const category = await prisma.category.update({
-        where: { id },
+        where: { id, deletedAt: null },
         data: {
           name: body.name,
           imageUrl: body.imageUrl,
@@ -246,7 +247,7 @@ export const categoriesRoute = new Elysia({ prefix: "/categories" })
 
     try {
       const category = await prisma.category.findUnique({
-        where: { id },
+        where: { id, deletedAt: null },
         include: { _count: { select: { products: true } } }
       });
 
@@ -255,8 +256,12 @@ export const categoriesRoute = new Elysia({ prefix: "/categories" })
         return status(400, { message: "Cannot delete category with existing products" });
       }
 
-      await prisma.category.delete({ where: { id } });
-      return { success: true };
+      const deletedAt = new Date();
+      await prisma.category.update({
+        where: { id },
+        data: { deletedAt },
+      });
+      return { success: true, softDeleted: true, id, deletedAt };
     } catch (err: any) {
       return status(500, { message: "Failed to delete category" });
     }
diff --git a/apps/backend/src/routes/pages.ts b/apps/backend/src/routes/pages.ts
index b67f36d..73abe39 100644
--- a/apps/backend/src/routes/pages.ts
+++ b/apps/backend/src/routes/pages.ts
@@ -734,7 +734,7 @@ export async function hydrateSectionPayload(section: any, lang: string) {
     if (Array.isArray(payload.categoryIds) && payload.categoryIds.length > 0) {
       const ids = payload.categoryIds.map(Number);
       categories = await prisma.category.findMany({
-        where: { id: { in: ids } },
+        where: { id: { in: ids }, deletedAt: null },
         include: {
           translations: true,
           _count: {
@@ -745,6 +745,7 @@ export async function hydrateSectionPayload(section: any, lang: string) {
       categories.sort((a, b) => ids.indexOf(a.id) - ids.indexOf(b.id));
     } else {
       categories = await prisma.category.findMany({
+        where: { deletedAt: null },
         include: {
           translations: true,
           _count: {
diff --git a/apps/backend/src/routes/products.ts b/apps/backend/src/routes/products.ts
index bdcd676..a64705f 100644
--- a/apps/backend/src/routes/products.ts
+++ b/apps/backend/src/routes/products.ts
@@ -21,6 +21,18 @@ function defaultProductDetailSections(productId: number) {
   ];
 }
 
+async function assertActiveCategory(categoryId: number, client: any = prisma) {
+  const category = await client.category.findFirst({
+    where: { id: categoryId, deletedAt: null },
+    select: { id: true },
+  });
+  if (!category) {
+    const error = new Error("Category not found");
+    (error as any).code = "CATEGORY_NOT_FOUND";
+    throw error;
+  }
+}
+
 export const productsRoute = new Elysia({ prefix: "/products" })
   .decorate("validateVariants", (options: any[] = [], variants: any[] = []) => {
     if (options.length > 3) throw new Error("Options array length cannot exceed 3.");
@@ -522,7 +534,10 @@ export const productsRoute = new Elysia({ prefix: "/products" })
         const updatedProduct = await prisma.$transaction(async (tx) => {
           // 1. Update basic product info
           const updateData: any = {};
-          if (categoryId !== undefined) updateData.categoryId = categoryId;
+          if (categoryId !== undefined) {
+            await assertActiveCategory(categoryId, tx);
+            updateData.categoryId = categoryId;
+          }
           if (body.options !== undefined) updateData.options = body.options;
           
           const prod = await tx.product.update({
@@ -632,6 +647,9 @@ export const productsRoute = new Elysia({ prefix: "/products" })
 
         return { success: true, product: updatedProduct };
       } catch (err: any) {
+        if (err?.code === "CATEGORY_NOT_FOUND") {
+          return status(400, { success: false, message: "Category not found" });
+        }
         console.error("Update product error:", err);
         return status(500, { success: false, message: err?.message || "Failed to update product" });
       }
@@ -690,12 +708,15 @@ export const productsRoute = new Elysia({ prefix: "/products" })
         const product = await prisma.$transaction(async (tx) => {
           let categoryId = payload.categoryId;
           if (!categoryId && payload.categoryName) {
-            let cat = await tx.category.findUnique({ where: { name: payload.categoryName } });
+            let cat = await tx.category.findFirst({
+              where: { name: payload.categoryName, deletedAt: null },
+            });
             if (!cat) {
               cat = await tx.category.create({ data: { name: payload.categoryName } });
             }
             categoryId = cat.id;
           }
+          if (categoryId) await assertActiveCategory(categoryId, tx);
 
           let brandId = payload.brandId;
           if (!brandId && payload.brandName) {
@@ -775,6 +796,9 @@ export const productsRoute = new Elysia({ prefix: "/products" })
 
         return { success: true, product };
       } catch (err: any) {
+        if (err?.code === "CATEGORY_NOT_FOUND") {
+          return status(400, { success: false, message: "Category not found" });
+        }
         console.error("Create product error:", err);
         return status(500, { success: false, message: err?.message || "Failed to create product" });
       }
@@ -806,12 +830,15 @@ export const productsRoute = new Elysia({ prefix: "/products" })
 
             let categoryId = payload.categoryId;
             if (!categoryId && payload.categoryName) {
-              let cat = await tx.category.findUnique({ where: { name: payload.categoryName } });
+              let cat = await tx.category.findFirst({
+                where: { name: payload.categoryName, deletedAt: null },
+              });
               if (!cat) {
                 cat = await tx.category.create({ data: { name: payload.categoryName } });
               }
               categoryId = cat.id;
             }
+            if (categoryId) await assertActiveCategory(categoryId, tx);
 
             let brandId = payload.brandId;
             if (!brandId && payload.brandName) {
@@ -892,6 +919,9 @@ export const productsRoute = new Elysia({ prefix: "/products" })
 
         return { success: true, products: createdProducts };
       } catch (err: any) {
+        if (err?.code === "CATEGORY_NOT_FOUND") {
+          return status(400, { success: false, message: "Category not found" });
+        }
         console.error("Bulk create products error:", err);
         return status(500, { success: false, message: err?.message || "Failed to bulk create products" });
       }
diff --git a/apps/mcp-server/README.md b/apps/mcp-server/README.md
index 9d92c1d..ecdd183 100644
--- a/apps/mcp-server/README.md
+++ b/apps/mcp-server/README.md
@@ -34,6 +34,86 @@ bun run dev
 - `update_store_settings_translation` อัปเดตข้อความแปลของ store settings
 - `update_footer_content` อัปเดตเนื้อหา footer และลิงก์ที่เกี่ยวข้อง
 
+## Mega Menu LLM Workflow
+
+Header Mega Menu uses the `main` menu payload tree. The website renders this structure:
+
+```text
+Root -> Column -> Link -> Child Link
+```
+
+Supported localized text keys are:
+
+```text
+th, en, ja, zh, vi, ko, lo, it
+```
+
+LLM agents should use this workflow for every menu edit:
+
+1. `capture_menu_snapshot` for `main`
+2. `get_mega_menu_tree`
+3. `validate_mega_menu_tree`
+4. Plan operations from diagnostics and current `nodeId` values
+5. `bulk_menu_operations` with `dryRun: true`
+6. Review `preview.diff`, `preview.before`, `preview.after`, `issues`, and `warnings`
+7. Apply only after approval
+8. Run `validate_mega_menu_tree` again
+9. Use `restore_menu_snapshot` if the applied result is wrong
+
+Do not add a Link directly under root. Add a Column under Root first, then add Links under that Column.
+
+Dry-run responses are expected to include path-based diffs such as:
+
+```json
+{
+  "path": "payload[0].columns[0].links[0].label.it",
+  "before": null,
+  "after": "Candele"
+}
+```
+
+`validate_mega_menu_tree` reports:
+
+- missing locale keys, especially `lo` and `it`
+- unsupported translation keys
+- duplicate or missing `nodeId`
+- invalid URL shape
+- placeholder text
+- empty columns
+- featured card issues
+- desktop render limits such as hidden columns or links
+
+## Category Management LLM Workflow
+
+Product categories are managed by backend `/categories` APIs through MCP. Supported localized text keys are:
+
+```text
+th, en, ja, zh, vi, ko, lo, it
+```
+
+LLM agents should use this workflow for category edits:
+
+1. `list_categories` with `lang: "all"` to discover category IDs and current translations
+2. `create_category`, `update_category`, `update_category_translations`, or `delete_category` with `dryRun: true`
+3. Review the preview and product counts
+4. Apply only after the intended change is clear
+5. Run `list_categories` again to verify
+
+Backend category support currently covers:
+
+- base `name`
+- `imageUrl`
+- localized names
+- product-count guarded soft delete (`deletedAt`)
+
+Backend category support does not currently cover:
+
+- slug
+- nested parent/child hierarchy
+- sort order
+- active/inactive state
+- restore/undelete workflow
+
 ## Scripts
 
 - `bun run dev`
diff --git a/apps/mcp-server/index.ts b/apps/mcp-server/index.ts
index 48a5bb9..4fcf521 100644
--- a/apps/mcp-server/index.ts
+++ b/apps/mcp-server/index.ts
@@ -14,6 +14,7 @@ const PRODUCTION_BACKEND_URL = process.env.MCP_BACKEND_URL_PRODUCTION || "https:
 let BACKEND_URL = process.env.MCP_BACKEND_URL || LOCAL_BACKEND_URL;
 const ADMIN_USERNAME = process.env.MCP_ADMIN_USERNAME || process.env.ADMIN_USERNAME || "admin";
 const ADMIN_PASSWORD = process.env.MCP_ADMIN_PASSWORD || process.env.ADMIN_PASSWORD || "homaroma123";
+const CATEGORY_LOCALES = ["th", "en", "ja", "zh", "vi", "ko", "lo", "it"] as const;
 
 let authToken = "";
 
@@ -49,6 +50,37 @@ async function performLogin() {
   }
 }
 
+function validateCategoryLocaleMap(translations: any) {
+  if (!translations || typeof translations !== "object" || Array.isArray(translations)) {
+    throw new Error("translations must be an object keyed by locale codes.");
+  }
+
+  const entries = Object.entries(translations);
+  if (entries.length === 0) {
+    throw new Error("translations must include at least one locale.");
+  }
+
+  for (const [locale, value] of entries) {
+    if (!CATEGORY_LOCALES.includes(locale as any)) {
+      throw new Error(`Unsupported locale "${locale}". Supported locales: ${CATEGORY_LOCALES.join(", ")}`);
+    }
+    if (typeof value !== "string" || value.trim().length === 0) {
+      throw new Error(`translations.${locale} must be a non-empty string.`);
+    }
+  }
+}
+
+function compactCategory(category: any) {
+  if (!category) return null;
+  return {
+    id: category.id,
+    name: category.name,
+    imageUrl: category.imageUrl ?? null,
+    productCount: category._count?.products ?? category.productCount ?? undefined,
+    translations: category.translations ?? undefined,
+  };
+}
+
 const server = new Server(
   {
     name: "homaroma-mcp",
@@ -96,8 +128,74 @@ server.setRequestHandler(ListToolsRequestSchema, async () => {
       },
       {
         name: "list_categories",
-        description: "List all product categories with their translations",
-        inputSchema: { type: "object", properties: {} }
+        description: "List all product categories with translations and product counts. Use lang=all when you need every localized name.",
+        inputSchema: {
+          type: "object",
+          properties: {
+            lang: { type: "string", description: "Language code: th, en, ja, zh, vi, ko, lo, it, or all" }
+          }
+        }
+      },
+      {
+        name: "get_category_products",
+        description: "Fetch one category plus its products. Use this before delete_category to see whether products block deletion.",
+        inputSchema: {
+          type: "object",
+          properties: {
+            id: { type: "number", description: "Category ID" },
+            lang: { type: "string", description: "Language code: th, en, ja, zh, vi, ko, lo, it, or all" },
+            page: { type: "number", description: "Page number, default 1" },
+            limit: { type: "number", description: "Products per page, default 12" }
+          },
+          required: ["id"]
+        }
+      },
+      {
+        name: "create_category",
+        description: "Create a product category. Backend supports base name, imageUrl, and translations. It does not support slug, hierarchy, sort order, or active state for categories.",
+        inputSchema: {
+          type: "object",
+          properties: {
+            name: { type: "string", description: "Base category name. Use Thai or the primary display name." },
+            imageUrl: { type: ["string", "null"], description: "Optional image URL." },
+            translations: {
+              type: "object",
+              description: "Optional locale map for category names. Supported locales: th, en, ja, zh, vi, ko, lo, it."
+            },
+            dryRun: { type: "boolean", description: "Preview only. No category is created." }
+          },
+          required: ["name"]
+        }
+      },
+      {
+        name: "update_category",
+        description: "Update category base name, image URL, and/or translations. Use dryRun first. Backend supports name and imageUrl only for base category fields.",
+        inputSchema: {
+          type: "object",
+          properties: {
+            id: { type: "number", description: "Category ID" },
+            name: { type: "string", description: "Optional base category name." },
+            imageUrl: { type: ["string", "null"], description: "Optional image URL. Pass null to remove." },
+            translations: {
+              type: "object",
+              description: "Optional locale map for category names. Supported locales: th, en, ja, zh, vi, ko, lo, it."
+            },
+            dryRun: { type: "boolean", description: "Preview only. No category is updated." }
+          },
+          required: ["id"]
+        }
+      },
+      {
+        name: "delete_category",
+        description: "Soft-delete a category by setting deletedAt. Backend refuses deletion when products still reference the category. Use dryRun first to check product count.",
+        inputSchema: {
+          type: "object",
+          properties: {
+            id: { type: "number", description: "Category ID" },
+            dryRun: { type: "boolean", description: "Preview only. No category is deleted." }
+          },
+          required: ["id"]
+        }
       },
       {
         name: "search_products",
@@ -131,12 +229,28 @@ server.setRequestHandler(ListToolsRequestSchema, async () => {
           type: "object",
           properties: {
             id: { type: "number", description: "Category ID" },
-            lang: { type: "string", description: "Language code (th, en, ja, zh, vi, ko)" },
+            lang: { type: "string", enum: ["th", "en", "ja", "zh", "vi", "ko", "lo", "it"], description: "Language code" },
             name: { type: "string", description: "Translated category name" }
           },
           required: ["id", "lang", "name"]
         }
       },
+      {
+        name: "update_category_translations",
+        description: "Add or update multiple category translations in one call. Supported locales: th, en, ja, zh, vi, ko, lo, it.",
+        inputSchema: {
+          type: "object",
+          properties: {
+            id: { type: "number", description: "Category ID" },
+            translations: {
+              type: "object",
+              description: "Locale map, for example { \"th\": \"ชุดโซ่สเตอร์\", \"en\": \"Chain & Sprocket Kits\" }"
+            },
+            dryRun: { type: "boolean", description: "Preview only. No translations are updated." }
+          },
+          required: ["id", "translations"]
+        }
+      },
       {
         name: "update_category_image",
         description: "Update the image URL for a specific category.",
@@ -855,9 +969,161 @@ server.setRequestHandler(CallToolRequestSchema, async (request) => {
         return { content: [{ type: "text", text: JSON.stringify(res.data, null, 2) }] };
       }
       case "list_categories": {
-        const res = await api.get(`/categories`);
+        const lang = params.lang ? `?lang=${encodeURIComponent(String(params.lang))}` : "";
+        const res = await api.get(`/categories${lang}`);
         return { content: [{ type: "text", text: JSON.stringify(res.data, null, 2) }] };
       }
+      case "get_category_products": {
+        const { id } = params as any;
+        const query = new URLSearchParams();
+        if (params.lang) query.set("lang", String(params.lang));
+        if (params.page) query.set("page", String(params.page));
+        if (params.limit) query.set("limit", String(params.limit));
+        const suffix = query.toString() ? `?${query.toString()}` : "";
+        const res = await api.get(`/categories/${id}/products${suffix}`);
+        return { content: [{ type: "text", text: JSON.stringify(res.data, null, 2) }] };
+      }
+      case "create_category": {
+        const { name, imageUrl = null, translations, dryRun } = params as any;
+        if (typeof name !== "string" || name.trim().length === 0) {
+          throw new Error("name must be a non-empty string.");
+        }
+        if (translations !== undefined) validateCategoryLocaleMap(translations);
+
+        const payload = { name: name.trim(), imageUrl };
+        if (dryRun) {
+          return {
+            content: [{
+              type: "text",
+              text: JSON.stringify({
+                success: true,
+                dryRun: true,
+                operation: "create_category",
+                preview: {
+                  create: payload,
+                  translations: translations ?? null,
+                  backendSupport: {
+                    fields: ["name", "imageUrl", "translations"],
+                    unsupportedFields: ["slug", "parentId", "sortOrder", "isActive"],
+                  },
+                },
+              }, null, 2)
+            }]
+          };
+        }
+
+        const created = await api.post(`/categories`, payload);
+        let translationResult: any = null;
+        if (translations) {
+          const mergedTranslations = { th: name.trim(), ...translations };
+          const translationRes = await api.patch(`/categories/${created.data.id}/translations`, { name: mergedTranslations });
+          translationResult = translationRes.data;
+        }
+        return {
+          content: [{
+            type: "text",
+            text: JSON.stringify({
+              success: true,
+              operation: "create_category",
+              category: translationResult?.category ?? created.data,
+              translations: translationResult?.translations ?? [],
+            }, null, 2)
+          }]
+        };
+      }
+      case "update_category": {
+        const { id, name, imageUrl, translations, dryRun } = params as any;
+        if (name !== undefined && (typeof name !== "string" || name.trim().length === 0)) {
+          throw new Error("name must be a non-empty string when provided.");
+        }
+        if (translations !== undefined) validateCategoryLocaleMap(translations);
+
+        const beforeList = await api.get(`/categories?lang=all`);
+        const before = Array.isArray(beforeList.data)
+          ? beforeList.data.find((cat: any) => cat.id === id)
+          : null;
+        if (!before) {
+          throw new Error(`Category with id ${id} not found.`);
+        }
+
+        const baseUpdate: any = {};
+        if (name !== undefined) baseUpdate.name = name.trim();
+        if (imageUrl !== undefined) baseUpdate.imageUrl = imageUrl;
+
+        if (dryRun) {
+          return {
+            content: [{
+              type: "text",
+              text: JSON.stringify({
+                success: true,
+                dryRun: true,
+                operation: "update_category",
+                categoryId: id,
+                preview: {
+                  before: compactCategory(before),
+                  baseUpdate,
+                  translations: translations ?? null,
+                  backendSupport: {
+                    fields: ["name", "imageUrl", "translations"],
+                    unsupportedFields: ["slug", "parentId", "sortOrder", "isActive"],
+                  },
+                },
+              }, null, 2)
+            }]
+          };
+        }
+
+        let updated: any = before;
+        if (Object.keys(baseUpdate).length > 0) {
+          const updateRes = await api.put(`/categories/${id}`, baseUpdate);
+          updated = updateRes.data;
+        }
+        let translationResult: any = null;
+        if (translations) {
+          const translationRes = await api.patch(`/categories/${id}/translations`, { name: translations });
+          translationResult = translationRes.data;
+          updated = translationResult?.category ?? updated;
+        }
+        return {
+          content: [{
+            type: "text",
+            text: JSON.stringify({
+              success: true,
+              operation: "update_category",
+              category: updated,
+              translations: translationResult?.translations ?? [],
+            }, null, 2)
+          }]
+        };
+      }
+      case "delete_category": {
+        const { id, dryRun } = params as any;
+        const details = await api.get(`/categories/${id}/products?lang=all&limit=1`);
+        const productCount = details.data?.category?._count?.products ?? details.data?.meta?.total ?? 0;
+        const category = details.data?.category ?? { id };
+
+        if (dryRun) {
+          return {
+            content: [{
+              type: "text",
+              text: JSON.stringify({
+                success: productCount === 0,
+                dryRun: true,
+                operation: "delete_category",
+                category,
+                productCount,
+                blocked: productCount > 0,
+                message: productCount > 0
+                  ? "Backend will refuse soft deletion because this category has products."
+                  : "Category can be soft-deleted. The record will be hidden from category lists but kept in the database.",
+              }, null, 2)
+            }]
+          };
+        }
+
+        const res = await api.delete(`/categories/${id}`);
+        return { content: [{ type: "text", text: JSON.stringify({ ...res.data, operation: "soft_delete_category", categoryId: id }, null, 2) }] };
+      }
       case "search_products": {
         const search = params.search ? `&search=${encodeURIComponent(params.search)}` : "";
         const limit = params.limit ? `&limit=${params.limit}` : "&limit=10";
@@ -889,6 +1155,7 @@ server.setRequestHandler(CallToolRequestSchema, async (request) => {
       }
       case "update_category_translation": {
         const { id, lang, name } = params as any;
+        validateCategoryLocaleMap({ [lang]: name });
         const res = await api.patch(`/categories/${id}/translations`, {
           name: { [lang]: name }
         });
@@ -896,6 +1163,43 @@ server.setRequestHandler(CallToolRequestSchema, async (request) => {
           content: [{ type: "text", text: JSON.stringify(res.data, null, 2) }]
         };
       }
+      case "update_category_translations": {
+        const { id, translations, dryRun } = params as any;
+        validateCategoryLocaleMap(translations);
+
+        if (dryRun) {
+          const beforeList = await api.get(`/categories?lang=all`);
+          const before = Array.isArray(beforeList.data)
+            ? beforeList.data.find((cat: any) => cat.id === id)
+            : null;
+          if (!before) {
+            throw new Error(`Category with id ${id} not found.`);
+          }
+          return {
+            content: [{
+              type: "text",
+              text: JSON.stringify({
+                success: true,
+                dryRun: true,
+                operation: "update_category_translations",
+                categoryId: id,
+                preview: {
+                  before: compactCategory(before),
+                  translations,
+                  changedLocales: Object.keys(translations),
+                },
+              }, null, 2)
+            }]
+          };
+        }
+
+        const res = await api.patch(`/categories/${id}/translations`, {
+          name: translations
+        });
+        return {
+          content: [{ type: "text", text: JSON.stringify(res.data, null, 2) }]
+        };
+      }
       case "update_category_image": {
         const { id, imageUrl } = params as any;
         const res = await api.patch(`/categories/${id}/image`, {
diff --git a/apps/mcp-server/menu-toolkit.ts b/apps/mcp-server/menu-toolkit.ts
index 4148016..55b58a7 100644
--- a/apps/mcp-server/menu-toolkit.ts
+++ b/apps/mcp-server/menu-toolkit.ts
@@ -5,19 +5,88 @@ import {
   applyMenuMoveNode,
   applyMenuRemoveNode,
   applyMenuUpdateTranslation,
+  buildMenuMutationPreview,
   collectMenuLinksFromTree,
   createMenuSnapshot,
-  describeMenuNode,
   normalizeMenuPayloadForWrite,
   restoreMenuSnapshot,
   validateMenuItems,
   validateMenuNodeData,
   validateMenuTranslations,
   validateMenuTreeSnapshot,
-  cloneMenuValue,
   isPlainObject,
+  SUPPORTED_MENU_LOCALES,
 } from "./menu-tools";
 
+const localizedTextSchema = {
+  type: "object",
+  description: `Localized text. Allowed locale keys: ${SUPPORTED_MENU_LOCALES.join(", ")}. Provide at least th or en; include lo and it when creating production-ready header menu content.`,
+  properties: Object.fromEntries(SUPPORTED_MENU_LOCALES.map((locale) => [locale, { type: "string" }])),
+  additionalProperties: false,
+} as const;
+
+const menuLinkNodeSchema = {
+  type: "object",
+  description: "Mega Menu Link node. Valid under a Column or another Link. Renders as a clickable link; child links are shown inline up to the desktop limit.",
+  properties: {
+    nodeId: { type: "string", description: "Existing node UUID. Omit for new nodes; MCP will generate one." },
+    label: localizedTextSchema,
+    url: { type: "string", description: "Internal path starting with /, or http(s)://, mailto:, tel:" },
+    icon: { type: "string", description: "Optional icon registry key" },
+    imageUrl: { type: "string", description: "Optional hover/preview image URL" },
+    links: { type: "array", description: "Optional child links", items: { type: "object" } },
+  },
+  required: ["label", "url"],
+  additionalProperties: true,
+} as const;
+
+const menuColumnNodeSchema = {
+  type: "object",
+  description: "Mega Menu Column node. Valid only under Root. Contains links; it is not directly clickable.",
+  properties: {
+    nodeId: { type: "string", description: "Existing node UUID. Omit for new nodes; MCP will generate one." },
+    title: localizedTextSchema,
+    icon: { type: "string", description: "Optional icon registry key" },
+    links: { type: "array", items: menuLinkNodeSchema },
+  },
+  required: ["title", "links"],
+  additionalProperties: true,
+} as const;
+
+const rootMenuNodeSchema = {
+  type: "object",
+  description: "Mega Menu Root node. Valid only under root. Desktop renders root labels in the header; columns open in the mega panel on hover.",
+  properties: {
+    nodeId: { type: "string", description: "Existing node UUID. Omit for new nodes; MCP will generate one." },
+    label: localizedTextSchema,
+    url: { type: "string", description: "Internal path starting with /, or http(s)://, mailto:, tel:" },
+    rootImageUrl: { type: "string", description: "Optional fallback image for featured preview" },
+    columns: { type: "array", items: menuColumnNodeSchema },
+    featured: {
+      type: "object",
+      description: "Optional desktop featured card. If enabled, provide meaningful localized text and imageUrl/url where possible.",
+      properties: {
+        enabled: { type: "boolean" },
+        sectionTitle: localizedTextSchema,
+        badge: localizedTextSchema,
+        title: localizedTextSchema,
+        subtitle: localizedTextSchema,
+        ctaLabel: localizedTextSchema,
+        price: { type: "string" },
+        imageUrl: { type: "string" },
+        url: { type: "string" },
+        focalPoint: {
+          type: "object",
+          properties: { x: { type: "string" }, y: { type: "string" } },
+        },
+      },
+      additionalProperties: true,
+    },
+  },
+  required: ["label", "url", "columns"],
+  additionalProperties: true,
+} as const;
+
 export const MENU_TOOL_DEFINITIONS = [
   {
     name: "get_menu",
@@ -82,9 +151,19 @@ export const MENU_TOOL_DEFINITIONS = [
   },
   {
     name: "get_mega_menu_tree",
-    description: "Read Mega Menu (main) payload, auto-generate nodeId for all nodes if missing, and return the tree.",
+    description: `Read Mega Menu (main) payload, auto-generate nodeId for all structural nodes if missing, and return the tree. Supported locales: ${SUPPORTED_MENU_LOCALES.join(", ")}.`,
     inputSchema: { type: "object", properties: {} }
   },
+  {
+    name: "validate_mega_menu_tree",
+    description: "Validate the current Mega Menu (main) tree for LLM-safe editing. Reports missing locales, invalid node shape, duplicate nodeId, unsupported translation keys, placeholder text, URL issues, and desktop render limits.",
+    inputSchema: {
+      type: "object",
+      properties: {
+        includeTree: { type: "boolean", description: "Include the normalized menu tree in the response. Default false." }
+      }
+    }
+  },
   {
     name: "capture_menu_snapshot",
     description: "Capture the current state of a menu so it can be restored later.",
@@ -110,7 +189,7 @@ export const MENU_TOOL_DEFINITIONS = [
   },
   {
     name: "bulk_menu_operations",
-    description: "Apply multiple menu tree operations in a single transaction. Supports add_node, update_translation, move_node, and remove_node.",
+    description: `Apply multiple Mega Menu operations in a single transaction. Workflow: capture_menu_snapshot -> validate_mega_menu_tree -> bulk_menu_operations with dryRun true -> user approval -> apply. Supports add_node, update_translation, move_node, and remove_node. Supported locales: ${SUPPORTED_MENU_LOCALES.join(", ")}.`,
     inputSchema: {
       type: "object",
       properties: {
@@ -127,8 +206,11 @@ export const MENU_TOOL_DEFINITIONS = [
               nodeId: { type: "string", description: "Target node ID for update/move/remove" },
               newParentId: { type: "string", description: "New parent node ID for move_node" },
               orderIndex: { type: "number", description: "Insertion index for move_node" },
-              translations: { type: "object", description: "Translation map for update_translation" },
-              nodeData: { type: "object", description: "Node data for add_node" }
+              translations: { ...localizedTextSchema, description: "Translation map for update_translation. Only locale keys are accepted." },
+              nodeData: {
+                oneOf: [rootMenuNodeSchema, menuColumnNodeSchema, menuLinkNodeSchema],
+                description: "Node data for add_node. Shape depends on parent: parentId=root => Root node; parent is Root => Column node; parent is Column/Link => Link node."
+              }
             },
             required: ["type"]
           }
@@ -139,28 +221,31 @@ export const MENU_TOOL_DEFINITIONS = [
   },
   {
     name: "add_menu_node",
-    description: "Add a new node to the Mega Menu tree. CRITICAL RULE: Mega Menu structure is Root -> Column -> Link. Do NOT add a Link directly under Root. If you want to add a Link, you MUST check if a Column exists first. If no Column exists, create a Column node first, then add the Link under that Column.",
+    description: `Add a new node to the Mega Menu tree. Structure is Root -> Column -> Link -> Child Link. Do not add a Link directly under root. Use dryRun first. Supported locales: ${SUPPORTED_MENU_LOCALES.join(", ")}.`,
     inputSchema: {
       type: "object",
       properties: {
         parentId: { type: "string", description: "UUID of parent node, or 'root'" },
         dryRun: { type: "boolean", description: "Preview the mutation without saving it" },
-        nodeData: { type: "object", description: "Node data including label, url, translations, etc." }
+        nodeData: {
+          oneOf: [rootMenuNodeSchema, menuColumnNodeSchema, menuLinkNodeSchema],
+          description: "Node data. If parentId is root/omitted, provide a Root node with label, url, and columns. If parent is a Root node, provide a Column node with title and links. If parent is a Column/Link, provide a Link node with label and url."
+        }
       },
       required: ["nodeData"]
     }
   },
   {
     name: "update_menu_translation",
-    description: "Update 6-language translations for a specific node in the Mega Menu",
+    description: `Update localized text for a specific node in the Mega Menu. Accepts only supported locale keys: ${SUPPORTED_MENU_LOCALES.join(", ")}. This updates label for root/link nodes or title for column nodes.`,
     inputSchema: {
       type: "object",
       properties: {
         nodeId: { type: "string", description: "UUID of the node" },
         dryRun: { type: "boolean", description: "Preview the mutation without saving it" },
         translations: {
-          type: "object",
-          description: "Object containing language codes as keys (th, en, etc.) and translated strings as values."
+          ...localizedTextSchema,
+          description: "Object containing locale codes as keys and translated strings as values. Unsupported keys are rejected."
         }
       },
       required: ["nodeId", "translations"]
@@ -359,6 +444,39 @@ export async function handleMenuTool(api: AxiosInstance, name: string, params: a
       }
       return { content: [{ type: "text", text: JSON.stringify(normalized.payload, null, 2) }] };
     }
+    case "validate_mega_menu_tree": {
+      const res = await api.get(`/menus/main`);
+      const menu = res.data;
+      const normalized = normalizeMenuPayloadForWrite(menu.payload);
+      if (normalized.modified) {
+        await api.put(`/menus/main`, { payload: normalized.payload, items: menu.items || [] });
+      }
+      const validation = validateMenuTreeSnapshot(normalized.payload);
+      return {
+        content: [
+          {
+            type: "text",
+            text: JSON.stringify(
+              {
+                success: validation.issues.length === 0,
+                operation: "validate_mega_menu_tree",
+                menuName: "main",
+                supportedLocales: validation.supportedLocales,
+                summary: validation.summary,
+                issueCount: validation.issues.length,
+                warningCount: validation.warnings.length,
+                issues: validation.issues,
+                warnings: validation.warnings,
+                diagnostics: validation.diagnostics,
+                tree: params.includeTree ? normalized.payload : undefined,
+              },
+              null,
+              2
+            )
+          }
+        ]
+      };
+    }
     case "capture_menu_snapshot": {
       const res = await api.get(`/menus/${params.name}`);
       const snapshot = createMenuSnapshot(res.data);
@@ -413,7 +531,9 @@ export async function handleMenuTool(api: AxiosInstance, name: string, params: a
 
       const res = await api.get(`/menus/${params.name}`);
       const menu = res.data;
-      const result = applyBulkMenuOperations(Array.isArray(menu.payload) ? menu.payload : [], params.operations);
+      const beforePayload = Array.isArray(menu.payload) ? menu.payload : [];
+      const result = applyBulkMenuOperations(beforePayload, params.operations);
+      const validation = validateMenuTreeSnapshot(result.payload);
 
       if (dryRun) {
         return {
@@ -421,7 +541,17 @@ export async function handleMenuTool(api: AxiosInstance, name: string, params: a
             {
               type: "text",
               text: JSON.stringify(
-                { success: true, dryRun: true, operation: "bulk_menu_operations", menuName: params.name, warnings: result.warnings, applied: result.applied, preview: { nodeCount: result.payload.length } },
+                {
+                  success: validation.issues.length === 0,
+                  dryRun: true,
+                  operation: "bulk_menu_operations",
+                  menuName: params.name,
+                  warnings: [...result.warnings, ...validation.warnings],
+                  issues: validation.issues,
+                  diagnostics: validation.diagnostics,
+                  applied: result.applied,
+                  preview: buildMenuMutationPreview(beforePayload, result.payload),
+                },
                 null,
                 2
               )
@@ -436,11 +566,23 @@ export async function handleMenuTool(api: AxiosInstance, name: string, params: a
         writeBody.isActive = menu.isActive;
       }
       const writeRes = await api.put(`/menus/${params.name}`, writeBody);
+      const writtenCheck = validateMenuTreeSnapshot(normalized.payload);
       return {
         content: [
           {
             type: "text",
-            text: JSON.stringify({ success: true, operation: "bulk_menu_operations", menuName: params.name, warnings: result.warnings, applied: result.applied, nodeCount: normalized.payload.length }, null, 2)
+            text: JSON.stringify(
+              {
+                success: true,
+                operation: "bulk_menu_operations",
+                menuName: params.name,
+                warnings: [...result.warnings, ...writtenCheck.warnings],
+                applied: result.applied,
+                summary: writtenCheck.summary,
+              },
+              null,
+              2
+            )
           }
         ]
       };
@@ -454,21 +596,36 @@ export async function handleMenuTool(api: AxiosInstance, name: string, params: a
       if (validation.issues.length > 0) {
         throw new Error(`Invalid menu node: ${validation.issues.join("; ")}`);
       }
-      const result = applyMenuAddNode(Array.isArray(menu.payload) ? menu.payload : [], parentId, nodeData);
+      const beforePayload = Array.isArray(menu.payload) ? menu.payload : [];
+      const result = applyMenuAddNode(beforePayload, parentId, nodeData);
+      const treeCheck = validateMenuTreeSnapshot(result.payload);
 
       if (dryRun) {
         return {
           content: [
             {
               type: "text",
-              text: JSON.stringify({ success: true, dryRun: true, operation: "add_menu_node", nodeId: result.nodeId, warnings: validation.warnings, preview: { nodeCount: result.payload.length } }, null, 2)
+              text: JSON.stringify(
+                {
+                  success: treeCheck.issues.length === 0,
+                  dryRun: true,
+                  operation: "add_menu_node",
+                  nodeId: result.nodeId,
+                  warnings: [...validation.warnings, ...treeCheck.warnings],
+                  issues: treeCheck.issues,
+                  diagnostics: treeCheck.diagnostics,
+                  preview: buildMenuMutationPreview(beforePayload, result.payload, result.nodeId),
+                },
+                null,
+                2
+              )
             }
           ]
         };
       }
 
       await api.put(`/menus/main`, { payload: result.payload, items: menu.items || [] });
-      return { content: [{ type: "text", text: JSON.stringify({ success: true, nodeId: result.nodeId, nodeCount: result.payload.length }, null, 2) }] };
+      return { content: [{ type: "text", text: JSON.stringify({ success: true, operation: "add_menu_node", nodeId: result.nodeId, summary: validateMenuTreeSnapshot(result.payload).summary }, null, 2) }] };
     }
     case "update_menu_translation": {
       const { nodeId, translations } = params;
@@ -479,63 +636,108 @@ export async function handleMenuTool(api: AxiosInstance, name: string, params: a
       }
       const res = await api.get(`/menus/main`);
       const menu = res.data;
-      const result = applyMenuUpdateTranslation(Array.isArray(menu.payload) ? menu.payload : [], nodeId, translations);
+      const beforePayload = Array.isArray(menu.payload) ? menu.payload : [];
+      const result = applyMenuUpdateTranslation(beforePayload, nodeId, translations);
+      const treeCheck = validateMenuTreeSnapshot(result.payload);
 
       if (dryRun) {
         return {
           content: [
             {
               type: "text",
-              text: JSON.stringify({ success: true, dryRun: true, operation: "update_menu_translation", warnings: validation.warnings, preview: { nodeCount: result.payload.length } }, null, 2)
+              text: JSON.stringify(
+                {
+                  success: treeCheck.issues.length === 0,
+                  dryRun: true,
+                  operation: "update_menu_translation",
+                  nodeId,
+                  warnings: [...validation.warnings, ...treeCheck.warnings],
+                  issues: treeCheck.issues,
+                  diagnostics: treeCheck.diagnostics,
+                  preview: buildMenuMutationPreview(beforePayload, result.payload, nodeId),
+                },
+                null,
+                2
+              )
             }
           ]
         };
       }
 
       await api.put(`/menus/main`, { payload: result.payload, items: menu.items || [] });
-      return { content: [{ type: "text", text: JSON.stringify({ success: true, nodeId, nodeCount: result.payload.length }, null, 2) }] };
+      return { content: [{ type: "text", text: JSON.stringify({ success: true, operation: "update_menu_translation", nodeId, summary: validateMenuTreeSnapshot(result.payload).summary }, null, 2) }] };
     }
     case "move_menu_node": {
       const { nodeId, newParentId, orderIndex } = params;
       const dryRun = !!params.dryRun;
       const res = await api.get(`/menus/main`);
       const menu = res.data;
-      const result = applyMenuMoveNode(Array.isArray(menu.payload) ? menu.payload : [], nodeId, newParentId, orderIndex);
+      const beforePayload = Array.isArray(menu.payload) ? menu.payload : [];
+      const result = applyMenuMoveNode(beforePayload, nodeId, newParentId, orderIndex);
+      const treeCheck = validateMenuTreeSnapshot(result.payload);
 
       if (dryRun) {
         return {
           content: [
             {
               type: "text",
-              text: JSON.stringify({ success: true, dryRun: true, operation: "move_menu_node", preview: { nodeCount: result.payload.length } }, null, 2)
+              text: JSON.stringify(
+                {
+                  success: treeCheck.issues.length === 0,
+                  dryRun: true,
+                  operation: "move_menu_node",
+                  nodeId,
+                  warnings: treeCheck.warnings,
+                  issues: treeCheck.issues,
+                  diagnostics: treeCheck.diagnostics,
+                  preview: buildMenuMutationPreview(beforePayload, result.payload, nodeId),
+                },
+                null,
+                2
+              )
             }
           ]
         };
       }
 
       await api.put(`/menus/main`, { payload: result.payload, items: menu.items || [] });
-      return { content: [{ type: "text", text: JSON.stringify({ success: true, nodeCount: result.payload.length }, null, 2) }] };
+      return { content: [{ type: "text", text: JSON.stringify({ success: true, operation: "move_menu_node", nodeId, summary: validateMenuTreeSnapshot(result.payload).summary }, null, 2) }] };
     }
     case "remove_menu_node": {
       const { nodeId } = params;
       const dryRun = !!params.dryRun;
       const res = await api.get(`/menus/main`);
       const menu = res.data;
-      const result = applyMenuRemoveNode(Array.isArray(menu.payload) ? menu.payload : [], nodeId);
+      const beforePayload = Array.isArray(menu.payload) ? menu.payload : [];
+      const result = applyMenuRemoveNode(beforePayload, nodeId);
+      const treeCheck = validateMenuTreeSnapshot(result.payload);
 
       if (dryRun) {
         return {
           content: [
             {
               type: "text",
-              text: JSON.stringify({ success: true, dryRun: true, operation: "remove_menu_node", removedNode: result.removedNode, preview: { nodeCount: result.payload.length } }, null, 2)
+              text: JSON.stringify(
+                {
+                  success: treeCheck.issues.length === 0,
+                  dryRun: true,
+                  operation: "remove_menu_node",
+                  removedNode: result.removedNode,
+                  warnings: treeCheck.warnings,
+                  issues: treeCheck.issues,
+                  diagnostics: treeCheck.diagnostics,
+                  preview: buildMenuMutationPreview(beforePayload, result.payload, nodeId),
+                },
+                null,
+                2
+              )
             }
           ]
         };
       }
 
       await api.put(`/menus/main`, { payload: result.payload, items: menu.items || [] });
-      return { content: [{ type: "text", text: JSON.stringify({ success: true, nodeCount: result.payload.length }, null, 2) }] };
+      return { content: [{ type: "text", text: JSON.stringify({ success: true, operation: "remove_menu_node", removedNode: result.removedNode, summary: validateMenuTreeSnapshot(result.payload).summary }, null, 2) }] };
     }
     default:
       return null;
diff --git a/apps/mcp-server/menu-tools.ts b/apps/mcp-server/menu-tools.ts
index e41d099..626c830 100644
--- a/apps/mcp-server/menu-tools.ts
+++ b/apps/mcp-server/menu-tools.ts
@@ -2,6 +2,11 @@ import crypto from "crypto";
 
 const MENU_NODE_ARRAY_KEYS = ["columns", "links", "items", "children"] as const;
 const MENU_NODE_VALUE_KEYS = ["label", "title", "url", ...MENU_NODE_ARRAY_KEYS] as const;
+const SUPPORTED_MENU_LOCALES = ["th", "en", "ja", "zh", "vi", "ko", "lo", "it"] as const;
+const PLACEHOLDER_TEXTS = new Set(["Badge", "Card title", "CTA label", "Section title", "Card subtitle", "New Menu", "New Column", "New Link"]);
+const MAX_DESKTOP_COLUMNS = 2;
+const MAX_DESKTOP_TOP_LEVEL_LINKS = 5;
+const MAX_DESKTOP_INLINE_CHILD_LINKS = 3;
 
 function isPlainObject(value: any) {
   return !!value && typeof value === "object" && !Array.isArray(value);
@@ -95,6 +100,196 @@ function describeMenuNode(node: any) {
   return "menu node";
 }
 
+function getMenuNodeType(node: any, parentType?: string) {
+  if (!isPlainObject(node)) return "invalid";
+  if (Array.isArray(node.columns)) return "root";
+  if (parentType === "root") return "column";
+  if (parentType === "column" || parentType === "link") return "link";
+  if (Array.isArray(node.links)) return "column";
+  if (typeof node.url === "string") return "link";
+  return "node";
+}
+
+function listLocalizedIssues(value: any, path: string, requiredBase = true) {
+  const issues: string[] = [];
+  const warnings: string[] = [];
+
+  if (value === undefined) {
+    issues.push(`${path}: missing localized text`);
+    return { issues, warnings };
+  }
+
+  if (typeof value === "string") {
+    if (!value.trim()) issues.push(`${path}: text must not be empty`);
+    return { issues, warnings };
+  }
+
+  if (!isPlainObject(value)) {
+    issues.push(`${path}: text must be a string or localized object`);
+    return { issues, warnings };
+  }
+
+  for (const key of Object.keys(value)) {
+    if (!(SUPPORTED_MENU_LOCALES as readonly string[]).includes(key)) {
+      issues.push(`${path}.${key}: unsupported key; allowed locale keys are ${SUPPORTED_MENU_LOCALES.join(", ")}`);
+    } else if (typeof value[key] !== "string" || !value[key].trim()) {
+      issues.push(`${path}.${key}: translation must be a non-empty string`);
+    } else if (PLACEHOLDER_TEXTS.has(value[key].trim())) {
+      warnings.push(`${path}.${key}: placeholder text "${value[key]}" should be replaced`);
+    }
+  }
+
+  if (requiredBase && !value.th && !value.en) {
+    issues.push(`${path}: provide at least th or en so website fallback has a stable label`);
+  }
+
+  for (const locale of SUPPORTED_MENU_LOCALES) {
+    if (!value[locale]) {
+      warnings.push(`${path}: missing ${locale} translation`);
+    }
+  }
+
+  return { issues, warnings };
+}
+
+function normalizeUrlIssue(url: any, path: string) {
+  if (typeof url !== "string" || !url.trim()) {
+    return `${path}: url must be a non-empty string`;
+  }
+  const trimmed = url.trim();
+  if (
+    !trimmed.startsWith("/") &&
+    !trimmed.startsWith("https://") &&
+    !trimmed.startsWith("http://") &&
+    !trimmed.startsWith("mailto:") &&
+    !trimmed.startsWith("tel:")
+  ) {
+    return `${path}: url must start with /, http(s)://, mailto:, or tel:`;
+  }
+  return null;
+}
+
+function getNodePath(payload: any[], nodeId?: string) {
+  if (!nodeId) return null;
+  const found = findNodeAndParent(payload, nodeId);
+  if (!found) return null;
+  const segments: string[] = [];
+  let current: any = found.node;
+
+  const findPath = (list: any[], target: any, base: string): boolean => {
+    for (let i = 0; i < list.length; i++) {
+      const item = list[i];
+      const currentPath = `${base}[${i}]`;
+      if (item === target) {
+        segments.push(currentPath);
+        return true;
+      }
+      for (const key of MENU_NODE_ARRAY_KEYS) {
+        if (Array.isArray(item?.[key]) && findPath(item[key], target, `${currentPath}.${key}`)) return true;
+      }
+    }
+    return false;
+  };
+
+  findPath(payload, current, "payload");
+  return segments[0] || null;
+}
+
+function summarizeMenuTree(payload: any[]) {
+  let totalNodes = 0;
+  let rootCount = 0;
+  let columnCount = 0;
+  let linkCount = 0;
+  let featuredCount = 0;
+  let hiddenDesktopColumns = 0;
+  let hiddenDesktopLinks = 0;
+  let hiddenDesktopChildLinks = 0;
+
+  const walk = (nodes: any[], parentType?: string) => {
+    nodes.forEach((node) => {
+      if (!isPlainObject(node)) return;
+      const type = getMenuNodeType(node, parentType);
+      totalNodes += 1;
+      if (type === "root") {
+        rootCount += 1;
+        if (isPlainObject(node.featured) && node.featured.enabled !== false) featuredCount += 1;
+        const columns = Array.isArray(node.columns) ? node.columns : [];
+        hiddenDesktopColumns += Math.max(columns.length - MAX_DESKTOP_COLUMNS, 0);
+        walk(columns, "root");
+      } else if (type === "column") {
+        columnCount += 1;
+        const links = Array.isArray(node.links) ? node.links : [];
+        hiddenDesktopLinks += Math.max(links.length - MAX_DESKTOP_TOP_LEVEL_LINKS, 0);
+        walk(links, "column");
+      } else if (type === "link") {
+        linkCount += 1;
+        const childLinks = Array.isArray(node.links) ? node.links : [];
+        hiddenDesktopChildLinks += Math.max(childLinks.length - MAX_DESKTOP_INLINE_CHILD_LINKS, 0);
+        walk(childLinks, "link");
+      }
+    });
+  };
+
+  walk(payload);
+  return {
+    rootCount,
+    columnCount,
+    linkCount,
+    totalNodes,
+    featuredCount,
+    desktopLimits: {
+      maxVisibleColumnsPerRoot: MAX_DESKTOP_COLUMNS,
+      maxVisibleLinksPerColumn: MAX_DESKTOP_TOP_LEVEL_LINKS,
+      maxVisibleChildLinksPerLink: MAX_DESKTOP_INLINE_CHILD_LINKS,
+      hiddenColumns: hiddenDesktopColumns,
+      hiddenLinks: hiddenDesktopLinks,
+      hiddenChildLinks: hiddenDesktopChildLinks,
+    },
+  };
+}
+
+function buildMenuDiff(before: any, after: any, basePath = "payload", limit = 80) {
+  const diff: any[] = [];
+
+  const walk = (a: any, b: any, path: string) => {
+    if (diff.length >= limit) return;
+    if (JSON.stringify(a) === JSON.stringify(b)) return;
+
+    if (Array.isArray(a) || Array.isArray(b)) {
+      const aArr = Array.isArray(a) ? a : [];
+      const bArr = Array.isArray(b) ? b : [];
+      const max = Math.max(aArr.length, bArr.length);
+      for (let i = 0; i < max; i++) walk(aArr[i], bArr[i], `${path}[${i}]`);
+      return;
+    }
+
+    if (isPlainObject(a) || isPlainObject(b)) {
+      const keys = new Set([...Object.keys(isPlainObject(a) ? a : {}), ...Object.keys(isPlainObject(b) ? b : {})]);
+      for (const key of keys) walk(a?.[key], b?.[key], `${path}.${key}`);
+      return;
+    }
+
+    diff.push({ path, before: a ?? null, after: b ?? null });
+  };
+
+  walk(before, after, basePath);
+  return { entries: diff, truncated: diff.length >= limit };
+}
+
+function buildMenuMutationPreview(before: any[], after: any[], changedNodeId?: string) {
+  const beforePayload = ensureMenuPayloadArray(before);
+  const afterPayload = ensureMenuPayloadArray(after);
+  const diff = buildMenuDiff(beforePayload, afterPayload);
+  const changedPath = getNodePath(afterPayload, changedNodeId) || getNodePath(beforePayload, changedNodeId);
+  return {
+    before: summarizeMenuTree(beforePayload),
+    after: summarizeMenuTree(afterPayload),
+    changedNodeId: changedNodeId || null,
+    changedPath,
+    diff,
+  };
+}
+
 function validateMenuNodeData(nodeData: any, parentId?: string | null) {
   const issues: string[] = [];
   const warnings: string[] = [];
@@ -110,13 +305,18 @@ function validateMenuNodeData(nodeData: any, parentId?: string | null) {
 
   for (const key of ["label", "title"] as const) {
     const value = nodeData[key];
-    if (value !== undefined && !isPlainObject(value) && typeof value !== "string") {
-      issues.push(`${key} must be a string or localized object`);
+    if (value !== undefined) {
+      const textCheck = listLocalizedIssues(value, key, false);
+      issues.push(...textCheck.issues);
+      warnings.push(...textCheck.warnings);
     }
   }
 
   if (nodeData.url !== undefined && typeof nodeData.url !== "string") {
     issues.push("url must be a string when provided");
+  } else if (nodeData.url !== undefined) {
+    const urlIssue = normalizeUrlIssue(nodeData.url, "url");
+    if (urlIssue) issues.push(urlIssue);
   }
 
   for (const key of MENU_NODE_ARRAY_KEYS) {
@@ -148,8 +348,14 @@ function validateMenuTranslations(translations: any) {
     return { issues, warnings };
   }
   for (const [key, value] of Object.entries(translations)) {
+    if (!(SUPPORTED_MENU_LOCALES as readonly string[]).includes(key)) {
+      issues.push(`unsupported locale "${key}"; allowed locale keys are ${SUPPORTED_MENU_LOCALES.join(", ")}`);
+      continue;
+    }
     if (typeof value !== "string") {
       issues.push(`translation for "${key}" must be a string`);
+    } else if (!value.trim()) {
+      issues.push(`translation for "${key}" must not be empty`);
     }
   }
   return { issues, warnings };
@@ -229,44 +435,102 @@ function ensureMenuPayloadArray(value: any) {
 function validateMenuTreeSnapshot(payload: any[]) {
   const issues: string[] = [];
   const warnings: string[] = [];
+  const diagnostics: Array<{ severity: "critical" | "high" | "medium" | "low"; path: string; nodeId?: string; message: string; recommendedFix: string }> = [];
   const seenNodeIds = new Set<string>();
 
-  const walk = (value: any, path: string) => {
+  const addIssue = (severity: "critical" | "high" | "medium" | "low", path: string, nodeId: string | undefined, message: string, recommendedFix: string) => {
+    const text = `${path}: ${message}`;
+    if (severity === "critical" || severity === "high") issues.push(text);
+    else warnings.push(text);
+    diagnostics.push({ severity, path, nodeId, message, recommendedFix });
+  };
+
+  const walk = (value: any, path: string, parentType?: string) => {
     if (Array.isArray(value)) {
-      value.forEach((child, index) => walk(child, `${path}[${index}]`));
+      value.forEach((child, index) => walk(child, `${path}[${index}]`, parentType));
       return;
     }
 
     if (!isPlainObject(value)) return;
 
     if (!isStructuralMenuNode(value)) {
-      warnings.push(`${path}: non-structural object present in menu tree`);
+      addIssue("low", path, undefined, "non-structural object present in menu tree", "Remove this object or convert it into a root, column, or link node.");
       return;
     }
 
+    const nodeId = typeof value.nodeId === "string" ? value.nodeId : undefined;
+    const nodeType = getMenuNodeType(value, parentType);
+
     if (value.nodeId && typeof value.nodeId === "string") {
       if (seenNodeIds.has(value.nodeId)) {
-        issues.push(`${path}: duplicate nodeId ${value.nodeId}`);
+        addIssue("critical", path, value.nodeId, `duplicate nodeId ${value.nodeId}`, "Assign a unique nodeId or let get_mega_menu_tree normalize IDs.");
       }
       seenNodeIds.add(value.nodeId);
     } else {
-      warnings.push(`${path}: missing nodeId`);
+      addIssue("medium", path, undefined, "missing nodeId", "Run get_mega_menu_tree once or update this node through MCP so a nodeId is generated.");
+    }
+
+    if (nodeType === "root") {
+      const labelCheck = listLocalizedIssues(value.label, `${path}.label`);
+      labelCheck.issues.forEach((message) => addIssue("high", path, nodeId, message.replace(`${path}.label: `, ""), "Provide a localized root label with at least th or en."));
+      labelCheck.warnings.forEach((message) => addIssue("low", path, nodeId, message.replace(`${path}.label: `, ""), "Fill missing locale labels, especially lo and it."));
+
+      const urlIssue = normalizeUrlIssue(value.url, `${path}.url`);
+      if (urlIssue) addIssue("high", path, nodeId, urlIssue.replace(`${path}.url: `, ""), "Set a valid root URL such as /shop.");
+
+      const columns = Array.isArray(value.columns) ? value.columns : [];
+      if (columns.length === 0 && isPlainObject(value.featured) && value.featured.enabled !== false) {
+        addIssue("medium", path, nodeId, "featured card is enabled on a root item with no columns", "Disable featured.enabled or add at least one column.");
+      }
+      if (columns.length > MAX_DESKTOP_COLUMNS) {
+        addIssue("medium", path, nodeId, `${columns.length - MAX_DESKTOP_COLUMNS} columns are hidden on desktop`, "Keep the most important columns first or reduce to two columns.");
+      }
+      if (isPlainObject(value.featured)) {
+        for (const key of ["sectionTitle", "badge", "title", "subtitle", "ctaLabel"] as const) {
+          if (value.featured[key] !== undefined) {
+            const check = listLocalizedIssues(value.featured[key], `${path}.featured.${key}`, false);
+            check.issues.forEach((message) => addIssue("medium", path, nodeId, message.replace(`${path}.featured.${key}: `, `featured.${key}: `), "Use only supported locale keys and non-empty strings."));
+            check.warnings.forEach((message) => addIssue("low", path, nodeId, message.replace(`${path}.featured.${key}: `, `featured.${key}: `), "Fill missing featured-card locales or remove placeholder text."));
+          }
+        }
+      }
+    } else if (nodeType === "column") {
+      const titleCheck = listLocalizedIssues(value.title, `${path}.title`);
+      titleCheck.issues.forEach((message) => addIssue("high", path, nodeId, message.replace(`${path}.title: `, ""), "Provide a localized column title with at least th or en."));
+      titleCheck.warnings.forEach((message) => addIssue("low", path, nodeId, message.replace(`${path}.title: `, ""), "Fill missing locale titles, especially lo and it."));
+      const links = Array.isArray(value.links) ? value.links : [];
+      if (links.length === 0) {
+        addIssue("medium", path, nodeId, "column has no links", "Add at least one link or remove the column.");
+      }
+      if (links.length > MAX_DESKTOP_TOP_LEVEL_LINKS) {
+        addIssue("medium", path, nodeId, `${links.length - MAX_DESKTOP_TOP_LEVEL_LINKS} links are hidden on desktop`, "Keep the most important links in the first five positions.");
+      }
+    } else if (nodeType === "link") {
+      const labelCheck = listLocalizedIssues(value.label, `${path}.label`);
+      labelCheck.issues.forEach((message) => addIssue("high", path, nodeId, message.replace(`${path}.label: `, ""), "Provide a localized link label with at least th or en."));
+      labelCheck.warnings.forEach((message) => addIssue("low", path, nodeId, message.replace(`${path}.label: `, ""), "Fill missing locale labels, especially lo and it."));
+      const urlIssue = normalizeUrlIssue(value.url, `${path}.url`);
+      if (urlIssue) addIssue("high", path, nodeId, urlIssue.replace(`${path}.url: `, ""), "Set a valid link URL.");
+      const childLinks = Array.isArray(value.links) ? value.links : [];
+      if (childLinks.length > MAX_DESKTOP_INLINE_CHILD_LINKS) {
+        addIssue("medium", path, nodeId, `${childLinks.length - MAX_DESKTOP_INLINE_CHILD_LINKS} child links are collapsed behind '+ more' on desktop`, "Keep the most important child links in the first three positions.");
+      }
     }
 
     const hasChildren = MENU_NODE_ARRAY_KEYS.some((key) => Array.isArray(value[key]));
     if (!hasChildren && !value.url) {
-      warnings.push(`${path}: container node has no children and no url`);
+      addIssue("medium", path, nodeId, "container node has no children and no url", "Add children, set a url, or remove the node.");
     }
 
     for (const key of MENU_NODE_ARRAY_KEYS) {
       if (Array.isArray(value[key])) {
-        walk(value[key], `${path}.${key}`);
+        walk(value[key], `${path}.${key}`, nodeType);
       }
     }
   };
 
   walk(payload, "payload");
-  return { issues, warnings };
+  return { issues, warnings, diagnostics, summary: summarizeMenuTree(payload), supportedLocales: SUPPORTED_MENU_LOCALES };
 }
 
 function applyMenuAddNode(tree: any[], parentId: string | undefined, nodeData: any): MenuTreeMutationResult {
@@ -464,6 +728,7 @@ function applyBulkMenuOperations(tree: any[], operations: any[]) {
 export {
   MENU_NODE_ARRAY_KEYS,
   MENU_NODE_VALUE_KEYS,
+  SUPPORTED_MENU_LOCALES,
   type MenuTreeMutationResult,
   applyBulkMenuOperations,
   applyMenuAddNode,
@@ -474,6 +739,7 @@ export {
   collectMenuLinksFromTree,
   createMenuSnapshot,
   describeMenuNode,
+  buildMenuMutationPreview,
   ensureMenuPayloadArray,
   findNodeAndParent,
   getChildrenArray,