docs: improvements and additions to admin customization chapters (medusajs#13049)

Author: shahednasser

www/apps/book/app/learn/fundamentals/admin/page.mdx

@@ -6,17 +6,17 @@ export const metadata = {
 
 In this chapter, you'll learn about the Medusa Admin dashboard and the possible ways to customize it.
 
-## What is the Medusa Admin?
-
-The Medusa Admin is an intuitive dashboard that allows merchants to manage their ecommerce store. It provides management features related to products, orders, customers, and more.
-
 <Note title="Tip">
 
-To explore more what you can do with the Medusa Admin, check out the [User Guide](!user-guide!). These user guides are designed for merchants and provide the steps to perform any task within the Medusa Admin.
+To explore the Medusa Admin's commerce features, check out the [User Guide](!user-guide!). These user guides are designed for merchants and provide the steps to perform any task within the Medusa Admin.
 
 </Note>
 
-The Medusa Admin is built with [Vite](https://vite.dev/). When you [install the Medusa application](../../installation/page.mdx), you also install the Medusa Admin. Then, when you start the Medusa application, you can access the Medusa Admin at `http://localhost:9000/app`.
+## What is the Medusa Admin?
+
+The Medusa Admin is an intuitive dashboard that allows merchants to manage their ecommerce store. It provides management features related to products, orders, customers, and more.
+
+The Medusa Admin is built with [Vite v5](https://v5.vite.dev/). When you [install the Medusa application](../../installation/page.mdx), you also install the Medusa Admin. Then, when you start the Medusa application, you can access the Medusa Admin at `http://localhost:9000/app`.
 
 <Note title="Tip">
 
@@ -37,7 +37,7 @@ The next chapters will cover these two topics in detail.
 
 ### What You Can't Customize in the Medusa Admin
 
-You can't customize the admin dashboard's layout, design, or the content of the existing pages (aside from injecting widgets).
+You can't customize the admin dashboard's layout, design, or the content of the existing pages (aside from injecting widgets). You also can't customize the login page, the authentication flow, or change the Medusa logo used in the admin dashboard.
 
 If your use case requires heavy customization of the admin dashboard, you can build a custom admin dashboard using Medusa's [Admin API routes](!api!/admin).
 

www/apps/book/app/learn/fundamentals/admin/widgets/page.mdx

@@ -139,3 +139,48 @@ Refer to [this reference](!resources!/admin-widget-injection-zones) for the full
 ## Admin Components List
 
 To build admin customizations that match the Medusa Admin's designs and layouts, refer to [this guide](!resources!/admin-components) to find common components.
+
+---
+
+## Show Widgets Conditionally
+
+In some cases, you may want to show a widget only if certain conditions are met. For example, you may want to show a widget only if the product has a brand.
+
+To disable the widget from showing, return an empty fragment from the widget component:
+
+```tsx title="src/admin/widgets/product-widget.tsx"
+import { defineWidgetConfig } from "@medusajs/admin-sdk"
+import { Container, Heading } from "@medusajs/ui"
+import { 
+  DetailWidgetProps, 
+  AdminProduct,
+} from "@medusajs/framework/types"
+
+// The widget
+const ProductWidget = ({ 
+  data,
+}: DetailWidgetProps<AdminProduct>) => {
+  if (!data.metadata?.brand) {
+    return <></> // Don't show the widget if the product has no brand
+  }
+
+  return (
+    <Container className="divide-y p-0">
+      <div className="flex items-center justify-between px-6 py-4">
+        <Heading level="h2">
+          Brand: {data.metadata.brand}
+        </Heading>
+      </div>
+    </Container>
+  )
+}
+
+// The widget's configurations
+export const config = defineWidgetConfig({
+  zone: "product.details.before",
+})
+
+export default ProductWidget
+```
+
+In the above example, you return an empty fragment if the product has no brand. Otherwise, you show the brand name in the widget.

www/apps/book/generated/edit-dates.mjs

@@ -19,7 +19,7 @@ export const generatedEditDates = {
   "app/learn/fundamentals/modules/container/page.mdx": "2025-05-21T15:07:12.059Z",
   "app/learn/fundamentals/workflows/execute-another-workflow/page.mdx": "2024-12-09T15:56:22.895Z",
   "app/learn/fundamentals/modules/loaders/page.mdx": "2025-06-16T13:34:16.462Z",
-  "app/learn/fundamentals/admin/widgets/page.mdx": "2024-12-09T16:43:24.260Z",
+  "app/learn/fundamentals/admin/widgets/page.mdx": "2025-07-25T12:55:14.744Z",
   "app/learn/fundamentals/data-models/page.mdx": "2025-03-18T07:55:56.252Z",
   "app/learn/fundamentals/modules/remote-link/page.mdx": "2024-09-30T08:43:53.127Z",
   "app/learn/fundamentals/api-routes/protected-routes/page.mdx": "2025-06-19T16:04:36.064Z",
@@ -29,7 +29,7 @@ export const generatedEditDates = {
   "app/learn/fundamentals/events-and-subscribers/emit-event/page.mdx": "2025-06-02T14:47:54.394Z",
   "app/learn/fundamentals/workflows/conditions/page.mdx": "2025-01-27T08:45:19.027Z",
   "app/learn/fundamentals/modules/module-link-directions/page.mdx": "2024-07-24T09:16:01+02:00",
-  "app/learn/fundamentals/admin/page.mdx": "2025-04-18T10:28:47.328Z",
+  "app/learn/fundamentals/admin/page.mdx": "2025-07-25T12:46:15.466Z",
   "app/learn/fundamentals/workflows/long-running-workflow/page.mdx": "2025-07-14T10:32:21.640Z",
   "app/learn/fundamentals/workflows/constructor-constraints/page.mdx": "2025-04-24T13:18:24.184Z",
   "app/learn/fundamentals/data-models/write-migration/page.mdx": "2025-07-23T15:32:18.008Z",