Loghound Beacon Signals - Automation Markers and Headless Tells

These are the codes the beacon reports about the browser it is running in. A code is an observation, not a verdict: the scorer correlates them with the transport and behaviour planes and owns the final number.

The weight column here is only this plane’s contribution to the client sub-score. The rules that turn them into a verdict are on How a visit is scored. This page has the automation markers and the headless tells; the browser claim probes and the consistency checks and human evidence have their own pages.

Only listed hostnames contribute signals

A beacon whose hostname is not in Settings › Measured sites still adds time on site, but none of the codes on these three pages is used. This stops a stranger’s page, loaded in a visitor’s browser, from reporting that visitor as automation.

01 · Definitive automation markers

Code	Weight	What it means
`automation_webdriver`	100	The navigator webdriver flag is true
`automation_cdc`	100	chromedriver’s marker property on window or document
`automation_playwright`	100	A Playwright binding
`automation_puppeteer`	100	A Puppeteer binding
`automation_selenium`	100	A Selenium, webdriver, driver or fxdriver binding
`automation_nightmare`	100	The Nightmare binding
`automation_phantom`	100	A PhantomJS binding
`automation_domauto`	100	A DOM automation controller

Presence is certainty. Absence means nothing at all.

Hiding these is a one-line patch that every serious scraper applies. They are cheap, they catch the lazy majority, and they are the reason the other planes exist.

02 · Headless-browser tells

Figure 1 — five families of observation, one scorer. The beacon reports raw measurements and the server does the comparing, because the server holds the authoritative User-Agent and a client cannot suppress a comparison it never performs.

headless_renderer

WebGL renderer is a software rasteriser

Weight: 90
Why the weight is what it is: A consumer desktop browser with no GPU is a container

headless_notif_contradiction

Notification permission says denied while the permissions API says prompt

Weight: 45
Why the weight is what it is: No real profile is in both states at once

headless_no_window_chrome

No browser-specific window object under a Chrome User-Agent

Weight: 40
Why the weight is what it is: Strong, but trivially faked

headless_zero_outer

The outer window width or height is zero

Weight: 40
Why the weight is what it is: Also legitimately zero in some cross-origin frames

headless_no_languages

The languages list is missing or empty

Weight: 25
Why the weight is what it is: Real browsers always populate it

headless_no_plugins

Zero plugins under a desktop Chrome User-Agent

Weight: 20
Why the weight is what it is: Modern Chrome exposes five PDF entries

headless_no_concurrency

Hardware concurrency is zero or absent under a Chrome User-Agent

Weight: 15
Why the weight is what it is: Some privacy-focused browsers clamp this value

headless_screen_eq_avail

Available screen size exactly equals screen size on a desktop User-Agent

Weight: 10
Why the weight is what it is: Also true of Linux kiosks and full-screen presentations

headless_no_chrome_runtime

No runtime object under a Chrome User-Agent

Weight: 10
Why the weight is what it is: Its presence on ordinary pages has changed across releases

Only the strong four — the renderer, the missing window object, the notification contradiction and the zero outer size — plus any automation marker set the headless boolean. The weak ones each have a real population of genuine humans behind them, and a boolean that is wrong for real visitors is worse than no boolean.

Automation & headless signals

Detection