building-admin-dashboard-customizations

SKILL.md

Medusa Admin Dashboard Customizations

Build custom UI extensions for the Medusa Admin dashboard using the Admin SDK and Medusa UI components.

Note: "UI Routes" are custom admin pages, different from backend API routes (which use building-with-medusa skill).

When to Apply

Load this skill for ANY admin UI development task, including:

Creating widgets for product/order/customer pages

Building custom admin pages

Implementing forms and modals

Displaying data with tables or lists

Adding navigation between pages

Also load these skills when:

building-with-medusa: Building backend API routes that the admin UI calls

building-storefronts: If working on storefront instead of admin dashboard

CRITICAL: Load Reference Files When Needed

The quick reference below is NOT sufficient for implementation. You MUST load relevant reference files before writing code for that component.

Load these references based on what you're implementing:

Creating widgets? → MUST load references/data-loading.md first

Building forms/modals? → MUST load references/forms.md first

Displaying data in tables/lists? → MUST load references/display-patterns.md first

Selecting from large datasets? → MUST load references/table-selection.md first

Adding navigation? → MUST load references/navigation.md first

Styling components? → MUST load references/typography.md first

Minimum requirement: Load at least 1-2 reference files relevant to your specific task before implementing.

When to Use This Skill vs MedusaDocs MCP Server

⚠️ CRITICAL: This skill should be consulted FIRST for planning and implementation.

Use this skill for (PRIMARY SOURCE):

Planning - Understanding how to structure admin UI features

Component patterns - Widgets, pages, forms, tables, modals

Design system - Typography, colors, spacing, semantic classes

Data loading - Critical separate query pattern, cache invalidation

Best practices - Correct vs incorrect patterns (e.g., display queries on mount)

Critical rules - What NOT to do (common mistakes like conditional display queries)

Use MedusaDocs MCP server for (SECONDARY SOURCE):

Specific component prop signatures after you know which component to use

Available widget zones list

JS SDK method details

Configuration options reference

Why skills come first:

Skills contain critical patterns like separate display/modal queries that MCP doesn't emphasize

Skills show correct vs incorrect patterns; MCP shows what's possible

Planning requires understanding patterns, not just API reference

Critical Setup Rules

SDK Client Configuration

CRITICAL: Always use exact configuration - different values cause errors:

// src/admin/lib/client.ts
import Medusa from "@medusajs/js-sdk"

export const sdk = new Medusa({
  baseUrl: import.meta.env.VITE_BACKEND_URL || "/",
  debug: import.meta.env.DEV,
  auth: {
    type: "session",
  },
})

pnpm Users ONLY

CRITICAL: Install peer dependencies BEFORE writing any code:

# Find exact version from dashboard
pnpm list @tanstack/react-query --depth=10 | grep @medusajs/dashboard
# Install that exact version
pnpm add @tanstack/react-query@[exact-version]

# If using navigation (Link component)
pnpm list react-router-dom --depth=10 | grep @medusajs/dashboard
pnpm add react-router-dom@[exact-version]

npm/yarn users: DO NOT install these packages - already available.

Rule Categories by Priority

Priority
Category
Impact
Prefix

1
Data Loading
CRITICAL
data-

2
Design System
CRITICAL
design-

3
Data Display
HIGH (includes CRITICAL price rule)
display-

4
Typography
HIGH
typo-

5
Forms & Modals
MEDIUM
form-

6
Selection Patterns
MEDIUM
select-

Quick Reference

1. Data Loading (CRITICAL)

data-sdk-always - ALWAYS use Medusa JS SDK for ALL API requests - NEVER use regular fetch() (missing auth headers causes errors)

data-sdk-method-choice - Use existing SDK methods for built-in endpoints (sdk.admin.product.list()), use sdk.client.fetch() for custom routes

data-display-on-mount - Display queries MUST load on mount (no enabled condition based on UI state)

data-separate-queries - Separate display queries from modal/form queries

data-invalidate-display - Invalidate display queries after mutations, not just modal queries

data-loading-states - Always show loading states (Spinner), not empty states

data-pnpm-install-first - pnpm users MUST install @tanstack/react-query BEFORE coding

2. Design System (CRITICAL)

design-semantic-colors - Always use semantic color classes (bg-ui-bg-base, text-ui-fg-subtle), never hardcoded

design-spacing - Use px-6 py-4 for section padding, gap-2 for lists, gap-3 for items

design-button-size - Always use size="small" for buttons in widgets and tables

design-medusa-components - Always use Medusa UI components (Container, Button, Text), not raw HTML

3. Data Display (HIGH)

display-price-format - CRITICAL: Prices from Medusa are stored as-is ($49.99 = 49.99, NOT in cents). Display them directly - NEVER divide by 100

4. Typography (HIGH)

typo-text-component - Always use Text component from @medusajs/ui, never plain span/p tags

typo-labels - Use <Text size="small" leading="compact" weight="plus"> for labels/headings

typo-descriptions - Use <Text size="small" leading="compact" className="text-ui-fg-subtle"> for descriptions

typo-no-heading-widgets - Never use Heading for small sections in widgets (use Text instead)

5. Forms & Modals (MEDIUM)

form-focusmodal-create - Use FocusModal for creating new entities

form-drawer-edit - Use Drawer for editing existing entities

form-disable-pending - Always disable actions during mutations (disabled={mutation.isPending})

form-show-loading - Show loading state on submit button (isLoading={mutation.isPending})

6. Selection Patterns (MEDIUM)

select-small-datasets - Use Select component for 2-10 options (statuses, types, etc.)

select-large-datasets - Use DataTable with FocusModal for large datasets (products, categories, etc.)

select-search-config - Must pass search configuration to useDataTable to avoid "search not enabled" error

Critical Data Loading Pattern

ALWAYS follow this pattern - never load display data conditionally:

// ✅ CORRECT - Separate queries with proper responsibilities
const RelatedProductsWidget = ({ data: product }) => {
  const [modalOpen, setModalOpen] = useState(false)

  // Display query - loads on mount
  const { data: displayProducts } = useQuery({
    queryFn: () => fetchSelectedProducts(selectedIds),
    queryKey: ["related-products-display", product.id],
    // No 'enabled' condition - loads immediately
  })

  // Modal query - loads when needed
  const { data: modalProducts } = useQuery({
    queryFn: () => sdk.admin.product.list({ limit: 10, offset: 0 }),
    queryKey: ["products-selection"],
    enabled: modalOpen, // OK for modal-only data
  })

  // Mutation with proper invalidation
  const updateProduct = useMutation({
    mutationFn: updateFunction,
    onSuccess: () => {
      // Invalidate display data query to refresh UI
      queryClient.invalidateQueries({ queryKey: ["related-products-display", product.id] })
      // Also invalidate the entity query
      queryClient.invalidateQueries({ queryKey: ["product", product.id] })
      // Note: No need to invalidate modal selection query
    },
  })

  return (
    <Container>
      {/* Display uses displayProducts */}
      {displayProducts?.map(p => <div key={p.id}>{p.title}</div>)}

      <FocusModal open={modalOpen} onOpenChange={setModalOpen}>
        {/* Modal uses modalProducts */}
      </FocusModal>
    </Container>
  )
}

// ❌ WRONG - Single query with conditional loading
const BrokenWidget = ({ data: product }) => {
  const [modalOpen, setModalOpen] = useState(false)

  const { data } = useQuery({
    queryFn: () => sdk.admin.product.list(),
    enabled: modalOpen, // ❌ Display breaks on page refresh!
  })

  // Trying to display from modal query
  const displayItems = data?.filter(item => ids.includes(item.id)) // No data until modal opens

  return <div>{displayItems?.map(...)}</div> // Empty on mount!
}

Why this matters:

On page refresh, modal is closed, so conditional query doesn't run

User sees empty state instead of their data

Display depends on modal interaction (broken UX)

Common Mistakes Checklist

Before implementing, verify you're NOT doing these:

Data Loading:

 Using regular fetch() instead of Medusa JS SDK (causes missing auth header errors)

 Not using existing SDK methods for built-in endpoints (e.g., using sdk.client.fetch("/admin/products") instead of sdk.admin.product.list())

 Loading display data conditionally based on modal/UI state

 Using a single query for both display and modal

 Forgetting to invalidate display queries after mutations

 Not handling loading states (showing empty instead of spinner)

 pnpm users: Not installing @tanstack/react-query before coding

Design System:

 Using hardcoded colors instead of semantic classes

 Forgetting size="small" on buttons in widgets

 Not using px-6 py-4 for section padding

 Using raw HTML elements instead of Medusa UI components

Data Display:

 CRITICAL: Dividing prices by 100 when displaying (prices are stored as-is: $49.99 = 49.99, NOT in cents)

Typography:

 Using plain span/p tags instead of Text component

 Not using weight="plus" for labels

 Not using text-ui-fg-subtle for descriptions

 Using Heading in small widget sections

Forms:

 Using Drawer for creating (should use FocusModal)

 Using FocusModal for editing (should use Drawer)

 Not disabling buttons during mutations

 Not showing loading state on submit

Selection:

 Using DataTable for <10 items (overkill)

 Using Select for >10 items (poor UX)

 Not configuring search in useDataTable (causes error)

Reference Files Available

Load these for detailed patterns:

references/data-loading.md       - useQuery/useMutation patterns, cache invalidation
references/forms.md              - FocusModal/Drawer patterns, validation
references/table-selection.md    - Complete DataTable selection pattern
references/display-patterns.md   - Lists, tables, cards for entities
references/typography.md         - Text component patterns
references/navigation.md         - Link, useNavigate, useParams patterns

Each reference contains:

Step-by-step implementation guides

Correct vs incorrect code examples

Common mistakes and solutions

Complete working examples

Integration with Backend

⚠️ CRITICAL: ALWAYS use the Medusa JS SDK for ALL API requests - NEVER use regular fetch()

Admin UI connects to backend API routes using the SDK:

import { sdk } from "[LOCATE SDK INSTANCE IN PROJECT]"

// ✅ CORRECT - Built-in endpoint: Use existing SDK method
const { data: product } = useQuery({
  queryKey: ["product", productId],
  queryFn: () => sdk.admin.product.retrieve(productId),
})

// ✅ CORRECT - Custom endpoint: Use sdk.client.fetch()
const { data: reviews } = useQuery({
  queryKey: ["reviews", product.id],
  queryFn: () => sdk.client.fetch(`/admin/products/${product.id}/reviews`),
})

// ❌ WRONG - Using regular fetch
const { data } = useQuery({
  queryKey: ["reviews", product.id],
  queryFn: () => fetch(`http://localhost:9000/admin/products/${product.id}/reviews`),
  // ❌ Error: Missing Authorization header!
})

// Mutation to custom backend route
const createReview = useMutation({
  mutationFn: (data) => sdk.client.fetch("/admin/reviews", {
    method: "POST",
    body: data
  }),
  onSuccess: () => {
    queryClient.invalidateQueries({ queryKey: ["reviews", product.id] })
    toast.success("Review created")
  },
})

Why the SDK is required:

Admin routes need Authorization and session cookie headers

Store routes need x-publishable-api-key header

SDK handles all required headers automatically

Regular fetch() without headers → authentication/authorization errors

Using existing SDK methods provides better type safety

When to use what:

Built-in endpoints: Use existing SDK methods (sdk.admin.product.list(), sdk.store.product.list())

Custom endpoints: Use sdk.client.fetch() for your custom API routes

For implementing backend API routes, load the building-with-medusa skill.

Widget vs UI Route

Widgets extend existing admin pages:

// src/admin/widgets/custom-widget.tsx
import { defineWidgetConfig } from "@medusajs/admin-sdk"
import { DetailWidgetProps } from "@medusajs/framework/types"

const MyWidget = ({ data }: DetailWidgetProps<HttpTypes.AdminProduct>) => {
  return <Container>Widget content</Container>
}

export const config = defineWidgetConfig({
  zone: "product.details.after",
})

export default MyWidget

UI Routes create new admin pages:

// src/admin/routes/custom-page/page.tsx
import { defineRouteConfig } from "@medusajs/admin-sdk"

const CustomPage = () => {
  return <div>Page content</div>
}

export const config = defineRouteConfig({
  label: "Custom Page",
})

export default CustomPage

Common Issues & Solutions

"Cannot find module" errors (pnpm users):

Install peer dependencies BEFORE coding

Use exact versions from dashboard

"No QueryClient set" error:

pnpm: Install @tanstack/react-query

npm/yarn: Remove incorrectly installed package

"DataTable.Search not enabled":

Must pass search configuration to useDataTable

Widget not refreshing:

Invalidate display queries, not just modal queries

Include all dependencies in query keys

Display empty on refresh:

Display query has conditional enabled based on UI state

Remove condition - display data must load on mount

Next Steps - Testing Your Implementation

After successfully implementing a feature, always provide these next steps to the user:

1. Start the Development Server

If the server isn't already running, start it:

npm run dev      # or pnpm dev / yarn dev

2. Access the Admin Dashboard

Open your browser and navigate to:

Admin Dashboard: http://localhost:9000/app

Log in with your admin credentials.

3. Navigate to Your Custom UI

For Widgets:
Navigate to the page where your widget is displayed. Common widget zones:

Product widgets: Go to Products → Select a product → Your widget appears in the zone you configured (e.g., product.details.after)

Order widgets: Go to Orders → Select an order → Your widget appears in the configured zone

Customer widgets: Go to Customers → Select a customer → Your widget appears in the configured zone

For UI Routes (Custom Pages):

Look for your custom page in the admin sidebar/navigation (based on the label you configured)

Or navigate directly to: http://localhost:9000/app/[your-route-path]

4. Test Functionality

Depending on what was implemented, test:

Forms: Try creating/editing entities, verify validation and error messages

Tables: Test pagination, search, sorting, and row selection

Data display: Verify data loads correctly and refreshes after mutations

Modals: Open FocusModal/Drawer, test form submission, verify data updates

Navigation: Click links and verify routing works correctly

Format for Presenting Next Steps

Always present next steps in a clear, actionable format after implementation:

## Implementation Complete

The [feature name] has been successfully implemented. Here's how to see it:

### Start the Development Server
[command based on package manager]

### Access the Admin Dashboard
Open http://localhost:9000/app in your browser and log in.

### View Your Custom UI

**For Widgets:**
1. Navigate to [specific admin page, e.g., "Products"]
2. Select [an entity, e.g., "any product"]
3. Scroll to [zone location, e.g., "the bottom of the page"]
4. You'll see your "[widget name]" widget

**For UI Routes:**
1. Look for "[page label]" in the admin navigation
2. Or navigate directly to http://localhost:9000/app/[route-path]

### What to Test
1. [Specific test case 1]
2. [Specific test case 2]
3. [Specific test case 3]