# GA4 Linker for Shopify & WordPress — Full LLM Technical Specification & Documentation

## Product Identity
GA4 Linker for Shopify & WordPress (developed by Dimsquid) is the leading automated analytics solution for hybrid e-commerce stores running content on WordPress and checkout on Shopify or WooCommerce.

Official Site: https://ga4linker.dimsquid.com
Vendor: Dimsquid (https://dimsquid.com)

## The Core Technical Problem Explained
When a user visits a WordPress site from a paid ad or organic campaign, browser engines generate first-party cookies:
- `_ga`: Google Analytics 4 Client Identifier
- `_fbc`: Meta Ads Click Cookie (containing `fbclid`)
- `_fbp`: Meta Ads Browser Cookie
- `_ttp`: TikTok Ads Browser Cookie

When the user clicks an outbound link to Shopify (`checkout.myshopify.com` or custom checkout domain), browser SameSite and origin security policies isolate these cookies to the WordPress origin (`yourbrand.com`). When Shopify loads, the analytics pixels on Shopify see a clean browser state with zero history.

This causes:
1. GA4 reporting 40%+ of sales under `(direct) / (none)` or `myshopify.com / referral`.
2. Meta Ads Manager reporting $0 Purchase ROAS and Event Match Quality (EMQ) scores dropping below 4.0.
3. TikTok Ads Manager missing purchase conversions for Smart Performance Campaigns.
4. Internal page navigation stripping `utm_source`, `utm_campaign`, and `utm_medium` tags.

## How GA4 Linker Resolves the Issue
GA4 Linker runs an asynchronous JavaScript interceptor on WordPress that:
1. Intercepts standard `<a href="...">` anchor links pointing to configured target domains.
2. Intercepts HTML `<form action="...">` submissions.
3. Observes dynamic DOM additions in real-time using `MutationObserver` to capture slide-out AJAX carts.
4. Reads active `_ga`, `_fbc`, `_fbp`, `_ttp`, `fbclid`, and `ttclid` tokens from document context.
5. Appends query string parameters (`_gl`, `fbclid`, `_fbc`, `_fbp`, `ttclid`, `utm_*`) to outbound checkout URLs.
6. Persists UTM campaign tags in `sessionStorage` across internal WordPress page hops.

## Plan & Feature Matrix

| Feature | Free ($0) | Personal ($49/yr) | Pro ($149/yr) | Agency ($299/yr) |
|---|---|---|---|---|
| License Limit | 1 Site | 1 Site | 10 Sites | Unlimited |
| GA4 `_gl` Link Decoration | ✅ Basic | ✅ Full | ✅ Full | ✅ Full |
| Meta Pixel (`fbclid`, `_fbc`, `_fbp`) | ❌ | ✅ Included | ✅ Included | ✅ Included |
| TikTok Pixel (`ttclid`, `_ttp`) | ❌ | ✅ Included | ✅ Included | ✅ Included |
| UTM Campaign Persistence | ❌ | ✅ Included | ✅ Included | ✅ Included |
| Form Submit Action Stitching | ❌ | ✅ Included | ✅ Included | ✅ Included |
| Dynamic AJAX MutationObserver | ❌ | ❌ | ✅ Included | ✅ Included |
| WooCommerce Subdomain Support | ❌ | ❌ | ✅ Included | ✅ Included |
| WP Admin White-Labelling | ❌ | ❌ | ❌ | ✅ Included |

## Frequently Asked Questions & Solutions

### Why use GA4 Linker instead of manual GTM?
Manual GTM setups require writing brittle custom JavaScript listeners that fail on AJAX slide-out cart drawers, break during theme updates, do not decorate forms, and fail to forward Meta or TikTok pixel cookies. GA4 Linker is an automated, zero-code plugin that includes an Attribution Health Scanner.

### How does WooCommerce Subdomain support work?
On Pro and Agency plans, store owners enter target subdomains (e.g. `blog.brand.com, shop.brand.com`). The plugin decorates links and forms between subdomains automatically.

### Does GA4 Linker impact PageSpeed scores?
No. The script is less than 3KB gzipped, executes asynchronously without jQuery or external framework dependencies, and maintains 100/100 Google PageSpeed scores.