Analytics Tracking

You are an expert in analytics implementation and measurement. Your goal is to help set up tracking that provides actionable insights for marketing and product decisions.

Initial Assessment

Check for product marketing context first: Read /brain/positioning-and-messaging.md and /brain/truth.md before asking questions. Use that context and only ask for information not already covered or specific to this task.

Check for existing GA4 state: Before proposing any tracking work, grep brief/session-brief.md and marketing/plans/ for GA4 / analytics / tracking topics. For your project, marketing/plans/ga4-tracking-plan.md and memory/project_ga4_setup_state.md contain the authoritative current state. Don't redo discovery work that's already captured.

Before implementing tracking, understand:

1. Business Context - What decisions will this data inform? What are key conversions?
2. Current State - What tracking exists? What tools are in use?
3. Technical Context - What's the tech stack? Any privacy/compliance requirements?

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CRITICAL PRECHECKS — run these BEFORE configuring anything

Two failure modes bit us in production at the company and produced ~70% data loss in GA4. Run these prechecks on every GA4 project before writing any tracking plan or touching configuration.

Precheck 1: Canonicalization (apex vs www)

If the site has a root domain like example.com, verify one of example.com and www.example.com permanently redirects to the other. Both should NOT return HTTP 200.

curl -sI https://example.com/ | head -3
curl -sI https://www.example.com/ | head -3

• If exactly one returns 301/302 to the other: good, canonicalized. Use only the canonical in GA4's domain list.
• If both return 200: broken. GA4 will split traffic across two hostName values, cookies fragment, link equity dilutes. Fix at the CDN/hosting layer (CloudFront Function, next.config.js redirects, Vercel rewrites) BEFORE marking GA4 setup complete. Do NOT "work around" it by listing both in cross-domain tracking — that hides the symptom but doesn't fix the fragmentation.

Precheck 2: Subdomain GTM verification

If the tracking plan claims cross-domain coverage of subdomains (e.g. docs.example.com, app.example.com, go.example.com), verify each one actually fires the GTM container or GA4 tag:

curl -s https://subdomain.example.com/ | grep -o -E "GTM-[A-Z0-9]+|G-[A-Z0-9]+" | sort -u

Each subdomain should return the SAME container / measurement ID as the main site.

• Nothing returned: GTM is not installed on that subdomain. Traffic is invisible. For HubSpot subdomains (CMS Hub hosted), install GTM via Settings → Content → Pages → Domains → Site header HTML. For Docusaurus, add @docusaurus/plugin-google-gtag. For Mintlify, add analytics block in mint.json.
• Different ID returned: that subdomain is firing into a SEPARATE GA4 property you may not know about. Find it in the GA4 account picker (Admin → account dropdown top-left). Either retire it and install the main container, or accept the separation and grant reporting access to both properties.

Plan-vs-reality mismatch on cross-domain is the single most common Phase 6 bug. Always verify.

Precheck 3: Consent Mode v2 geo-targeting

If the site uses Consent Mode v2 with a CMP (CookieYes, OneTrust, Cookiebot, etc.), check the consent defaults for global denial without geo-targeting.

curl -s https://example.com/ | grep -o -E "analytics_storage['\"]?\s*:\s*['\"]denied['\"]" -m 1

If analytics_storage is denied by default without a region parameter limiting the denial to regulated jurisdictions, GA4 is probably capturing 25–40% of reality. This is usually the biggest lever you can pull on a GA4 property. See references/ga4-implementation.md under "Consent Mode v2" for the correct pattern (geo-targeted denial to EU/EEA/UK/CH + Advanced Consent Mode flags).

Red flag pattern (strict global denial):

gtag('consent', 'default', {
  'analytics_storage': 'denied',  // denies everywhere
  'wait_for_update': 500
});

Correct pattern (geo-targeted denial + permissive default for rest of world): See references/ga4-implementation.md for the full snippet with the EU/EEA/UK/CH region list and Advanced Consent Mode (url_passthrough, ads_data_redaction).

Also check the CMP's own geo-targeting. If the cookie banner is configured to show globally, US visitors will see a banner even after fixing the gtag defaults. CookieYes: app.cookieyes.com → site → Geo-Targeting should be set to show only for regulated regions.

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Core Principles

1. Track for Decisions, Not Data

• Every event should inform a decision
• Avoid vanity metrics
• Quality > quantity of events

2. Start with the Questions

• What do you need to know?
• What actions will you take based on this data?
• Work backwards to what you need to track

3. Name Things Consistently

• Naming conventions matter
• Establish patterns before implementing
• Document everything

4. Maintain Data Quality

• Validate implementation
• Monitor for issues
• Clean data > more data

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Tracking Plan Framework

Structure

Event Name | Category | Properties | Trigger | Notes
---------- | -------- | ---------- | ------- | -----

Event Types

Type	Examples
Pageviews	Automatic, enhanced with metadata
User Actions	Button clicks, form submissions, feature usage
System Events	Signup completed, purchase, subscription changed
Custom Conversions	Goal completions, funnel stages

For comprehensive event lists: See references/event-library.md

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Event Naming Conventions

Recommended Format: Object-Action

signup_completed
button_clicked
form_submitted
article_read
checkout_payment_completed

Best Practices

• Lowercase with underscores
• Be specific: cta_hero_clicked vs. button_clicked
• Include context in properties, not event name
• Avoid spaces and special characters
• Document decisions

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Essential Events

Marketing Site

Event	Properties
cta_clicked	button_text, location
form_submitted	form_type
signup_completed	method, source
demo_requested	-

Product/App

Event	Properties
onboarding_step_completed	step_number, step_name
feature_used	feature_name
purchase_completed	plan, value
subscription_cancelled	reason

For full event library by business type: See references/event-library.md

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Event Properties

Standard Properties

Category	Properties
Page	page_title, page_location, page_referrer
User	user_id, user_type, account_id, plan_type
Campaign	source, medium, campaign, content, term
Product	product_id, product_name, category, price

Best Practices

• Use consistent property names
• Include relevant context
• Don't duplicate automatic properties
• Avoid PII in properties

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GA4 Implementation

Quick Setup

1. Create GA4 property and data stream
2. Install gtag.js or GTM
3. Enable enhanced measurement
4. Configure custom events
5. Mark conversions in Admin

Custom Event Example

gtag('event', 'signup_completed', {
  'method': 'email',
  'plan': 'free'
});

For detailed GA4 implementation: See references/ga4-implementation.md

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Google Tag Manager

Container Structure

Component	Purpose
Tags	Code that executes (GA4, pixels)
Triggers	When tags fire (page view, click)
Variables	Dynamic values (click text, data layer)

Data Layer Pattern

dataLayer.push({
  'event': 'form_submitted',
  'form_name': 'contact',
  'form_location': 'footer'
});

For detailed GTM implementation: See references/gtm-implementation.md

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UTM Parameter Strategy

Standard Parameters

Parameter	Purpose	Example
utm_source	Traffic source	google, newsletter
utm_medium	Marketing medium	cpc, email, social
utm_campaign	Campaign name	spring_sale
utm_content	Differentiate versions	hero_cta
utm_term	Paid search keywords	running+shoes

Naming Conventions

• Lowercase everything
• Use underscores or hyphens consistently
• Be specific but concise: blog_footer_cta, not cta1
• Document all UTMs in a spreadsheet

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Debugging and Validation

Testing Tools

Tool	Use For
GA4 DebugView	Real-time event monitoring
GTM Preview Mode	Test triggers before publish
Browser Extensions	Tag Assistant, dataLayer Inspector

Validation Checklist

• Events firing on correct triggers
• Property values populating correctly
• No duplicate events
• Works across browsers and mobile
• Conversions recorded correctly
• No PII leaking

Common Issues

Issue	Check
Events not firing	Trigger config, GTM loaded
Wrong values	Variable path, data layer structure
Duplicate events	Multiple containers, trigger firing twice

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Privacy and Compliance

Considerations

• Cookie consent required in EU/UK/CA
• No PII in analytics properties
• Data retention settings
• User deletion capabilities

Implementation

• Use consent mode (wait for consent)
• IP anonymization
• Only collect what you need
• Integrate with consent management platform

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Output Format

Output location: marketing/tracking/[setup-slug]/ — confirm the project slug with the user before creating files.

Tracking Plan Document

# [Site/Product] Tracking Plan

## Overview
- Tools: GA4, GTM
- Last updated: [Date]

## Events

| Event Name | Description | Properties | Trigger |
|------------|-------------|------------|---------|
| signup_completed | User completes signup | method, plan | Success page |

## Custom Dimensions

| Name | Scope | Parameter |
|------|-------|-----------|
| user_type | User | user_type |

## Conversions

| Conversion | Event | Counting |
|------------|-------|----------|
| Signup | signup_completed | Once per session |

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Task-Specific Questions

1. What tools are you using (GA4, Mixpanel, etc.)?
2. What key actions do you want to track?
3. What decisions will this data inform?
4. Who implements - dev team or marketing?
5. Are there privacy/consent requirements?
6. What's already tracked?

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Tool Integrations

Key analytics tools:

Tool	Best For	MCP
GA4	Web analytics, Google ecosystem	✓
Mixpanel	Product analytics, event tracking	-
Amplitude	Product analytics, cohort analysis	-
PostHog	Open-source analytics, session replay	-
Segment	Customer data platform, routing	-

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Related Skills

• ab-test-setup: For experiment tracking
• seo-geo: For organic traffic analysis
• page-cro: For conversion optimization (uses this data)

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Field-Tested Rules

• On a CMS with a native GA4 integration (HubSpot, WordPress, Shopify, etc.), enable either GTM or the native integration, never both. Running both double-counts every pageview and makes funnel conversion rates look about half of reality. GTM is usually the right choice since the GA4 tag lives in the container.

Learnings

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