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Sweep 02 Oct 2026 · 18:55Z Build v2.1.288 509 read Stable v2.1.285 Latest v2.1.287 Next v2.1.288 Feeds RSS JSON llms.txt llms-full.txt Unofficial
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tengu_violin_fhole

flag in the build JSON

A Claude Code feature flag, read out of the shipped bundle. It has been in the build since v2.1.287, including the newest one read.

Claude Code checks a new remote switch that is off unless turned on remotely, and what it controls is not visible

Not Anthropic's. This is the line from the earliest changelog entry here that named it, v2.1.287.

First seen v2.1.287 1 Oct 2026
Last seen v2.1.288 2 Oct 2026
Builds2 / 131on this box, as of v2.1.288
Written about v2.1.287 first named in a changelog, 1 Oct 2026
v2.1.287in the build not in the build never minedv2.1.288

In the changelogs

2

Releases whose published page names tengu_violin_fhole.

  1. v2.1.287
    A new off-by-default switch with no visible purpose yet

    Claude Code checks a new remote switch that is off unless turned on remotely, and what it controls is not visible

    gate cited by this entry, found in this entry's text

  2. v2.1.287
    Programs driving Claude Code can ask for a background task's output

    A new get_task_output request lets a program controlling Claude Code read a background task's output

    gate cited by this entry

Gate readings

1
ReleaseResolvedThis accountAnonymousCompiled default
v2.1.287 read on another version Off by default, switched on for this account on on 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.

Flag server, over time

4
Read asReadingFromUntilVersion installed
this account on 2026-09-30T19:15:05Z 2026-10-02T19:05:06Z v2.1.286 to v2.1.287
anonymous on 2026-09-30T16:45:05Z 2026-10-02T19:05:06Z v2.1.285 to v2.1.287
this account no longer carried 2026-09-30T17:30:08Z 2026-09-30T17:30:08Z v2.1.285
this account on 2026-09-30T17:26:32Z 2026-09-30T17:26:32Z v2.1.286

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

1

The earliest release whose published evidence quoted tengu_violin_fhole was v2.1.287, 1 Oct 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.

ReleaseDateThe span that was quoted
v2.1.2871 Oct 2026tengu_violin_fhole

Presence across releases

1
BuildsHow manyDatesReading
v2.1.287 – v2.1.2882 builds1 Oct 2026 → 2 Oct 2026 ◆in the build

Build by build

2

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.

BuildDateStateThe record behind it
v2.1.2871 Oct 2026·addedverdict: added · default bool:false
v2.1.2882 Oct 2026·presentverdict: present · default bool:false

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.

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