tengu_slate_bittern

A Claude Code feature flag, read out of the shipped bundle. It has been in the build since v2.1.257, including the newest one read.

Releases whose published page names tengu_slate_bittern.

1. v2.1.301 15 Oct 2026
   System prompt gains an alternate layout that is not yet in use

   Claude Code's system prompt can now be built in an alternate layout with extra sections, but the prompt sent in ordinary use is unchanged

   gate cited by this entry

2. v2.1.286 30 Sep 2026
   System prompt parts are now labelled; detached sessions skip some setup

   Claude Code labels and groups each part of its system prompt, and a new detached mode skips a setup step; the prompt text is the same

   gate cited by this entry

3. v2.1.257 1 Sep 2026
   New system-prompt section for reduced delegation on Opus 5

   A new prompt section adds reduced-delegation guidance for Opus-class models, skipped if already cached in memory.

   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.

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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.