The preview browser is locked to the local server and refuses to run if the lock fails.
tengu_cobalt_plinth_aspen Not enough to sayNothing here resolved what this flag was doing on this version, so nothing here should be read as on or off.
This account: no value returned · anonymous baseline: no value returned · compiled default in v2.1.247: on
Read once, for one account on one subscription tier, against v2.1.247. It isn't a statement about your account. What a flag value here can and cannot tell you
What's wrong with this entry?
The Chrome instance spawned for artifact preview is confined to the loopback preview host plus Google Fonts. Every other name is black-holed by host-resolver rules, proxies are off, new web contents and the GPU are disabled, and a fresh profile directory is created under a claude-artifact-preview- prefix. Before the real page loads, preview navigates to a throwaway local name and requires the failure to be net::ERR_NAME_NOT_RESOLVED; if the browser resolved it anyway, the run stops.
- Debugger-level request interception fails anything that is not the page itself or a fonts.googleapis / gstatic stylesheet path.
- An injected script deletes
RTCPeerConnectionand related APIs and, via a mutation observer, stripspreconnect,dns-prefetchandprerenderlinks plus speculation-rules scripts. - Workers or worklets that attach without waiting for the debugger also abort the run.
- Behind the same preview gate,
tengu_cobalt_plinth_aspen, as the rest of preview.
this browser ignored the preview network lock-down; preview stopped before loading the page
Strings lifted out of the shipped bundle, so the claim above can be checked against them.