Measure traffic from AI assistants

lib/ai-referrers.ts answers one question: did this visit come from an AI assistant, and which one. It is a pure function with no dependencies. It sends nothing anywhere and sets no cookie, so wiring it to your analytics is your decision and stays your decision.

Why this needs its own dimension

Assistant referrals do not group with search traffic in any default report. chatgpt.com arrives as an ordinary referral, sitting in the same list as a forum link and a newsletter, and perplexity.ai sits three rows below it. The one number that tells you whether writing for retrieval is working is scattered across a dozen rows nobody totals.

Classifying at the source collapses those rows into one dimension you can chart over time. That chart is the only feedback loop available here, because AI answer engines send no query data, no impression counts, and no rank.

Wire it up

Three lines against whatever you already run. Put them in a client component that renders on the post route, or on the server against the Referer header.

const ai = classifyReferrer(document.referrer)
if (ai) gtag('event', 'ai_referral', { ai_source: ai.source, ai_host: ai.host })

const ai = classifyReferrer(document.referrer)
if (ai) track('ai_referral', { source: ai.source, host: ai.host })

const ai = classifyReferrer(document.referrer)
if (ai) posthog.capture('ai_referral', { source: ai.source, host: ai.host })

Chart ai_source as the dimension and ai_host as the drill-down. The host is kept alongside the source deliberately: it is how you notice a new subdomain sending traffic before it has a name of its own.

The API

import { classifyReferrer, isAiReferrer } from '@/lib/ai-referrers'

classifyReferrer('https://chatgpt.com/c/abc123')
// { source: 'chatgpt', host: 'chatgpt.com' }

classifyReferrer('https://news.ycombinator.com/item?id=1')
// null

isAiReferrer(document.referrer)
// boolean

null covers empty referrers, direct traffic, unparseable strings, and every ordinary referral, so you can branch on truthiness and be done.

The input may be a full URL or a bare hostname. document.referrer gives you a full URL and a Referer header usually does too, but log pipelines and tag managers hand over bare hosts often enough that it is handled here rather than at every call site.

It is safe in a client component

lib/ai-referrers.ts has no server-only import, no Node built-ins, no config import, and no I/O. That is deliberate, so it can be imported from a 'use client' component and read document.referrer on first paint.

It is the only file in lib/ with that property. Everything else that touches config imports server-only, and a build-time check fails if that ever changes.

What it recognises

Four matching strategies, in order.

Adding a host to the other-ai list is the low-risk edit. Make it freely.

Why the integration is not shipped

Shipping a Google Analytics integration would mean choosing Google Analytics for you, adding a dependency to a block whose pitch is that it adds none, and owning a consent surface nobody here can see.

The classifier is the part that is genuinely hard to get right, and it is the part where a mistake is silent: a subdomain that stops matching does not throw, it quietly stops appearing in your numbers.

Also worth watching

npx agentblog@latest audit --crawlers /path/to/access.log

That parses a server or CDN access log and reports crawler hits per bot per week, verifying each hit against the operators' published IP ranges. User agent strings are trivially spoofed, so any count that trusts the string alone is reporting noise.