tengu_cobalt_plinth_yarrow

A Claude Code feature flag, read out of the shipped bundle. It was in the build from v2.1.239 and was gone by v2.1.242.

Releases whose published page names tengu_cobalt_plinth_yarrow.

1. v2.1.239 21 Aug 2026
   Three feature gates renamed, three retired

   Artifact syntax highlighting and mermaid diagrams are now always on; three other gates were renamed and stay off.

   gate cited by this entry, found in this entry's text

Two arms, because they disagree: this account is the one account this site reads and anonymous is a baseline with no identity attached. A reading says nothing about your account, and off cannot rule out a rollout both readings sit outside of. What these readings can and cannot show.

One row per unbroken stretch of one reading, newest first, from snapshots taken every twenty-five minutes or so. No longer carried is not off: it means the flag server stopped returning the gate at all, which is what a retired experiment looks like. The version column is what was installed when the reading was taken, not what caused it.

The earliest release whose published evidence quoted tengu_cobalt_plinth_yarrow was v2.1.239, 21 Aug 2026. That is the oldest release this project wrote about it, so it is a floor on the name's age and not the release that introduced it. It is not a presence reading: which builds carried the name is the table below.

One row per release since the first build this name was read out of. Absent means the build was read and the name was not in it, never mined means no bundle for that release was ever archived, and a declared type or a default is only ever what that release's own bundle stated.

Read out of the published npm bundle release by release, and out of Anthropic's own documentation as this site captured it. Nothing on this page is a description anybody here wrote about what the feature flag does. All feature flags.