tengu_serene_teacup
A Claude Code feature flag, read out of the shipped bundle. It has been in the build since v2.1.282, including the newest one read.
A new step at session start refreshes an internal setting called the atis pin
Not Anthropic's. This is the line from the earliest changelog entry here that named it, v2.1.282.
In the changelogs
2Releases whose published page names tengu_serene_teacup.
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v2.1.282
Sessions now refresh an internal setting when they start
A new step at session start refreshes an internal setting called the atis pin
gate cited by this entry
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v2.1.282
Feature-flag results can now depend on a stored pin value and refresh when it changes
Claude Code now sends a stored pin value when asking which features are switched on, keeps separate cached answers per pin, and re-asks when the pin changes
gate cited by this entry
Gate readings
1| Release | Resolved | This account | Anonymous | Compiled default |
|---|---|---|---|---|
| v2.1.282 read on another version | Not enough to say | no value returned | no value returned | on |
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.
First cited
2The earliest release whose published evidence quoted tengu_serene_teacup was v2.1.282, 24 Sep 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.
Presence across releases
1Build by build
2One 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.