---
name: shopify-admin-duplicate-sku-barcode-detector
role: merchandising
description: "Read-only: finds duplicate SKUs or barcodes across all product variants."
toolkit: shopify-admin, shopify-admin-execution
api_version: "2025-01"
graphql_operations:
  - productVariants:query
status: stable
compatibility: Claude Code, Cursor, Codex, Gemini CLI
---

## Purpose
Scans all product variants and identifies duplicate SKUs or barcodes — two or more variants sharing the same identifier. Duplicate SKUs cause inventory sync failures, incorrect order routing, and accounting mismatches. Read-only — no mutations.

## Prerequisites
- Authenticated Shopify CLI session: `shopify store auth --store <domain> --scopes read_products`
- API scopes: `read_products`

## Parameters

| Parameter | Type | Required | Default | Description |
|-----------|------|----------|---------|-------------|
| store | string | yes | — | Store domain (e.g., mystore.myshopify.com) |
| check_skus | bool | no | true | Check for duplicate SKUs |
| check_barcodes | bool | no | true | Check for duplicate barcodes |
| include_blank | bool | no | false | Flag variants with blank/null SKU |
| format | string | no | human | Output format: `human` or `json` |

## Safety

> ℹ️ Read-only skill — no mutations are executed. Safe to run at any time.

## Workflow Steps

1. **OPERATION:** `productVariants` — query
   **Inputs:** `first: 250`, select `sku`, `barcode`, `product { title }`, pagination cursor
   **Expected output:** All variants with SKU and barcode values; paginate until `hasNextPage: false`

2. Build in-memory map of `sku → [variants]` and `barcode → [variants]`

3. Report all keys with more than one variant (duplicates)

4. If `include_blank`: additionally flag variants where `sku` is null or empty string

## GraphQL Operations

```graphql
# productVariants:query — validated against api_version 2025-01
query VariantIdentifiers($after: String) {
  productVariants(first: 250, after: $after) {
    edges {
      node {
        id
        sku
        barcode
        title
        product {
          id
          title
          handle
          status
        }
      }
    }
    pageInfo {
      hasNextPage
      endCursor
    }
  }
}
```

## Session Tracking

**Claude MUST emit the following output at each stage. This is mandatory.**

**On start**, emit:
```
╔══════════════════════════════════════════════╗
║  SKILL: Duplicate SKU/Barcode Detector       ║
║  Store: <store domain>                       ║
║  Started: <YYYY-MM-DD HH:MM UTC>             ║
╚══════════════════════════════════════════════╝
```

**After each step**, emit:
```
[N/TOTAL] <QUERY|MUTATION>  <OperationName>
          → Params: <brief summary of key inputs>
          → Result: <count or outcome>
```

**On completion**, emit:

For `format: human` (default):
```
══════════════════════════════════════════════
DUPLICATE SKU / BARCODE REPORT
  Variants scanned:      <n>
  Duplicate SKUs found:  <n> groups
  Duplicate barcodes:    <n> groups
  Blank SKUs:            <n>

  Duplicate SKU groups:
    SKU "ABC-123"  — used by 2 variants:
      Product A / Blue / L
      Product B / Navy / XL
  Output: duplicates_<date>.csv
══════════════════════════════════════════════
```

For `format: json`, emit:
```json
{
  "skill": "duplicate-sku-barcode-detector",
  "store": "<domain>",
  "variants_scanned": 0,
  "duplicate_sku_groups": 0,
  "duplicate_barcode_groups": 0,
  "blank_skus": 0,
  "output_file": "duplicates_<date>.csv"
}
```

## Output Format
CSV file `duplicates_<YYYY-MM-DD>.csv` with columns:
`issue_type`, `duplicate_value`, `variant_id`, `product_title`, `variant_title`, `sku`, `barcode`

## Error Handling
| Error | Cause | Recovery |
|-------|-------|----------|
| `THROTTLED` | API rate limit exceeded | Wait 2 seconds, retry up to 3 times |
| No duplicates found | Clean catalog | Exit with ✅ no issues found |

## Best Practices
- Run this skill after every bulk product import — imports are the most common source of duplicate SKUs.
- A shared SKU across products is only valid if you intentionally use the same SKU for reprints or variants — most cases are data errors.
- Blank SKUs are not duplicates but can cause problems with 3PLs and fulfillment systems that require a SKU for every variant — use `include_blank: true` to surface them.
- After identifying duplicates, use the Shopify Admin UI or the `productVariantsBulkUpdate` mutation to correct SKU values.