shopify-admin-duplicate-customer-finder

What this skill does

## Purpose
Scans the customer database for likely duplicate records using email, phone, and name matching. Duplicate customer records cause split order history, incorrect LTV calculations, and incorrect marketing segmentation. Read-only — no mutations.

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

## Parameters

| Parameter | Type | Required | Default | Description |
|-----------|------|----------|---------|-------------|
| store | string | yes | — | Store domain (e.g., mystore.myshopify.com) |
| match_on | string | no | email | Match strategy: `email`, `phone`, `name`, or `all` |
| min_orders | integer | no | 0 | Only flag duplicates where at least one record has this many orders |
| format | string | no | human | Output format: `human` or `json` |

## Safety

> ℹ️ Read-only skill — no mutations are executed. Safe to run at any time. Duplicate merging is not supported by the Shopify Admin API — flagged duplicates must be merged manually in Shopify Admin.

## Workflow Steps

1. **OPERATION:** `customers` — query
   **Inputs:** `first: 250`, select `email`, `phone`, `firstName`, `lastName`, `numberOfOrders`, `totalSpentV2`, pagination cursor
   **Expected output:** All customers with contact and order data; paginate until `hasNextPage: false`

2. Build in-memory lookup maps:
   - `email → [customer_ids]`
   - `phone → [customer_ids]` (if `match_on` includes phone)
   - `"firstName lastName" → [customer_ids]` (if `match_on` includes name)

3. Report groups with > 1 customer per key as likely duplicates

## GraphQL Operations

```graphql
# customers:query — validated against api_version 2025-01
query CustomersForDeduplication($after: String) {
  customers(first: 250, after: $after) {
    edges {
      node {
        id
        displayName
        firstName
        lastName
        defaultEmailAddress {
          emailAddress
        }
        phone
        numberOfOrders
        amountSpent {
          amount
          currencyCode
        }
        createdAt
      }
    }
    pageInfo {
      hasNextPage
      endCursor
    }
  }
}
```

## Session Tracking

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

**On start**, emit:
```
╔══════════════════════════════════════════════╗
║  SKILL: Duplicate Customer Finder            ║
║  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 CUSTOMER REPORT
  Customers scanned:       <n>
  Duplicate groups found:  <n>
  Customers affected:      <n>

  Duplicate groups (sample):
    Email: [email protected]
      Customer A — <n> orders, $<n> spent, created <date>
      Customer B — <n> orders, $<n> spent, created <date>
  Output: duplicate_customers_<date>.csv
══════════════════════════════════════════════
```

For `format: json`, emit:
```json
{
  "skill": "duplicate-customer-finder",
  "store": "<domain>",
  "customers_scanned": 0,
  "duplicate_groups": 0,
  "customers_affected": 0,
  "output_file": "duplicate_customers_<date>.csv"
}
```

## Output Format
CSV file `duplicate_customers_<YYYY-MM-DD>.csv` with columns:
`duplicate_group_id`, `match_key`, `match_type`, `customer_id`, `name`, `email`, `phone`, `number_of_orders`, `total_spent`, `created_at`

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

## Best Practices
- Shopify does not provide a native merge API — flagged duplicates must be resolved manually in Shopify Admin (Customers → Merge).
- `match_on: email` finds the most reliable duplicates; `match_on: name` produces more false positives (common names).
- Prioritize duplicates where at least one record has orders — these affect LTV and marketing segmentation most.
- Common causes of duplicates: guest checkout followed by account creation, manual customer imports, or customers using multiple email addresses.