Shopify Admin Duplicate Customer Finder

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

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

# 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: user@example.com
      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:

{
  "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

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.