tengu_sleepy_shore
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.
The web search tool has a built-in choice between a quick, cheap search and a slower, thorough one, but it stays off unless configured
Not Anthropic's. This is the line from the earliest changelog entry here that named it, v2.1.282.
In the changelogs
4Releases whose published page names tengu_sleepy_shore.
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v2.1.283
Setting the web-search proxy variable no longer turns off fast web search
CLAUDE_CODE_WEBSEARCH_USE_CCR_PROXYno longer forces fast web search off, andCLAUDE_CODE_WEBSEARCH_CCR_PROXY_FASTis gonegate cited by this entry
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v2.1.282
Web search can offer a quick "standard" mode and a thorough "extended" mode, off by default
The web search tool has a built-in choice between a quick, cheap search and a slower, thorough one, but it stays off unless configured
gate cited by this entry
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v2.1.282
Fast web search can add an extra hint to Claude's instructions
When fast web search is on and a web search tool is available, Claude's system prompt gets an extra hint
gate cited by this entry
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v2.1.282
Web search instructions can be extended remotely, and a stray option is ignored
When fast web search is enabled, extra WebSearch tool instructions can be supplied remotely, and a
modevalue sent while it is off is droppedgate cited by this entry
Gate readings
2| Release | Resolved | This account | Anonymous | Compiled default |
|---|---|---|---|---|
| v2.1.283 read on another version | Not enough to say | no value returned | no value returned | not a boolean we can read |
| v2.1.282 read on another version | Not enough to say | no value returned | no value returned | not a boolean we can read |
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.
Flag server, over time
6| Read as | Reading | From | Until | Version installed |
|---|---|---|---|---|
| anonymous | {"enabled":true} | 2026-10-17T05:30:04Z | 2026-11-12T17:30:05Z | v2.1.302 to v2.1.322 |
| this account | {"enabled":true} | 2026-10-06T20:40:05Z | 2026-11-12T17:30:05Z | v2.1.292 to v2.1.322 |
| anonymous | no longer carried | 2026-10-17T05:25:57Z | 2026-10-17T05:25:57Z | v2.1.302 |
| anonymous | {"enabled":true} | 2026-10-06T20:20:07Z | 2026-10-17T05:10:04Z | v2.1.292 to v2.1.302 |
| this account | [] | 2026-09-28T20:40:07Z | 2026-10-06T20:20:07Z | v2.1.284 to v2.1.292 |
| anonymous | [] | 2026-09-28T20:30:06Z | 2026-10-06T20:10:06Z | v2.1.284 to v2.1.292 |
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.
First cited
2The earliest release whose published evidence quoted tengu_sleepy_shore 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
37One 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.