No debugger client attached to this tab after it loaded
The counter is 0: no DevTools-protocol client enabled Runtime on this tab after it loaded. Information only, because DevTools opened by a person counts too (severity: info).
What a detector infers
V8 keeps the console messages a page logs, which is why DevTools can show messages logged before it was opened. When any DevTools-protocol client enables the Runtime domain, the stored messages are replayed to it, and to describe a stored Error argument V8 formats its stack — which calls the page's Error.prepareStackTrace hook if there is one. An inline script at the top of the page installs a counting hook and logs one Error at load, and the audit reads the counter later.
Any client that enabled Runtime on this tab at any point since load has left a mark, including one that disabled it again immediately — the enable-then-disable sequence some modified automation libraries use so that live probes find nothing attached.
Measured 0 on Chrome, Edge and Linux Chrome with nothing attached, and 1 under a Playwright launch, under Playwright attaching with connectOverCDP after the page had loaded, under puppeteer-extra-plugin-stealth, and after a bare Runtime.enable followed by Runtime.disable. It is information only, like runtime-enable-leak and console-preview-proxy-trap, because a person who opens DevTools trips it too, as do extensions that use chrome.debugger.
Those rows ask whether a client is attached now; this one asks whether one ever was.
How to resolve it
Nothing to fix for a person with DevTools open. For an automation client, the mark is made at the moment Runtime is enabled, so disabling it afterwards does not remove it; only a client that never enables Runtime on the tab leaves the counter at 0.
Nearby checks in Automation surface
- The user agent names no headless product
headless-ua-tokenBoth of Chrome's headless modes name themselves in the user agent. - navigator.webdriver does not assert WebDriver control
webdriver-offThis check is intentionally one-way. The WebDriver specification defines navigator.webdriver as the browser's assertion that it is under… - navigator.webdriver is a native prototype getter returning false
webdriver-descriptor-integrityRather than reading the value, this check inspects the property's shape: it requires a getter on Navigator.prototype whose… - No Selenium / Puppeteer / Playwright globals
automation-globalsThis check tests a fixed list of roughly two dozen known names against both window and document (Selenium's __webdriver_evaluate /… - No anti-detect fingerprint setters left on window
antidetect-fingerprint-settersAnti-detect browsers in the Camoufox family apply a per-context fingerprint through helper functions published on the window object… - DevTools Runtime serialization is not active
runtime-enable-leakAn attached DevTools Runtime domain serialises console arguments and reads an Error stack accessor. - No console preview enumerated a prototype-chain Proxy
console-preview-proxy-trapDevTools has to look inside an object to show it to you, and in JavaScript looking inside an object is an observable act. - No Puppeteer / Playwright sourceURL marker
sourceurl-leakPuppeteer and Playwright evaluation labels can appear in main-world Error stacks.
Clearcote is a browser built for fingerprint coherence
It is a Chromium fork, maintained by the same people who wrote this reference. It ships as a compiled browser rather than as a stealth script injected into someone else's — which is a description of how it is built, and is not an argument about how it behaves on this check.
This audit takes no position on how Clearcote scores on Automation surface checks, on this one, or anywhere else. It has no baseline corpus of other people's fingerprints to rank you against and no vendor scoreboard — nearly every check is self-referential, asking one browser the same question through two independent APIs and reporting whether both answers can be true at once. It runs identically on any browser, including ours. Run it on yours and read the result yourself.
See the other checks in Automation surface — the family console-replay-trap belongs to.