tengu_fennel_godwit

A Claude Code feature flag, read out of the shipped bundle. It was in the build from v2.1.219 and was gone by v2.1.302.

Releases whose published page names tengu_fennel_godwit.

1. v2.1.219 24 Jul 2026
   Opus 5 gets an extra system-prompt instruction restricting AgentTool, workflows and deep-research

   On Opus 5, Claude is told not to spawn subagents, workflows or deep research unless you ask.

   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.

No release's published evidence quotes this name. The ledger indexes the Evidence lines of every changelog on this site, so this says nobody here has ever quoted it; it says nothing about how old the name is.

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.