tengu_velvety_sprout
A Claude Code feature flag, read out of the shipped bundle. It has been in the build since v2.1.281, including the newest one read.
The Agent tool can now keep tool results inside subagents instead of stripping them, controlled by a server-side switch
Not Anthropic's. This is the line from the earliest changelog entry here that named it, v2.1.281.
In the changelogs
4Releases whose published page names tengu_velvety_sprout.
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v2.1.301
Groundwork for alternative Agent and Skill tool instructions; artifact publish edits recorded
The Agent and Skill tool instructions can now take extra options with no visible effect yet, and artifact publish edits are now recorded
gate cited by this entry
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v2.1.293
Agent tool text now knows whether a subagent can be continued
The text for the tool that starts subagents now receives a flag, worked out from the available tools, saying whether continuing is available
gate cited by this entry
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v2.1.290
Subagent tool now receives a budget note based on where a request came from
The tool Claude uses to start subagents now gets a budget note based on where the request came from, plus a remote switch for keeping tool results
gate cited by this entry
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v2.1.281
Agent tool: preserving tool results in subagents is dark-launched
The Agent tool can now keep tool results inside subagents instead of stripping them, controlled by a server-side switch
gate cited by this entry, found in this entry's text
Gate readings
4| Release | Resolved | This account | Anonymous | Compiled default |
|---|---|---|---|---|
| v2.1.301 read on another version | Not enough to say | no value returned | no value returned | off |
| v2.1.293 read on another version | Not enough to say | no value returned | no value returned | off |
| v2.1.290 read on another version | Not enough to say | no value returned | no value returned | off |
| v2.1.281 read on another version | Not enough to say | no value returned | no value returned | off |
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_velvety_sprout was v2.1.281, 23 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
38One 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.