tengu_mellow_hollerith

A Claude Code feature flag, read out of the shipped bundle. It was in the build from v2.1.274 and was gone by v2.1.296.

Releases whose published page names tengu_mellow_hollerith.

1. v2.1.300 14 Oct 2026
   Six server-controlled switches are now checked early at startup

   Six features controlled from Anthropic's servers are now checked early at startup, and five are off unless switched on remotely

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

2. v2.1.274 16 Sep 2026
   New built-in "Claude Test" plugin for browser-based spec testing

   New built-in 'Claude Test' plugin runs plain-language specs against your local dev server in a real browser and reports PASS/FAIL

   gate cited by this entry

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_mellow_hollerith was v2.1.300, 14 Oct 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.