tengu_fizzy_wren
A Claude Code feature flag, read out of the shipped bundle. No mined inventory carries it: everything below comes from what this site has written about it.
The switch behind an unidentified feature was replaced by a new one that stays off unless Anthropic's servers turn it on
Not Anthropic's. This is the line from the earliest changelog entry here that named it, v2.1.323.
In the changelogs
2Releases whose published page names tengu_fizzy_wren.
-
v2.1.323
An unidentified feature moves to a new switch that is off by default
The switch behind an unidentified feature was replaced by a new one that stays off unless Anthropic's servers turn it on
gate cited by this entry, found in this entry's text
-
v2.1.323
The set of server-controlled experiments has changed
Claude Code dropped four server-controlled experiment switches and added many others, nearly all off unless switched on remotely
gate cited by this entry
Gate readings
1| Release | Resolved | This account | Anonymous | Compiled default |
|---|---|---|---|---|
| v2.1.323 read on another version | Not enough to say | no value returned | 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
8| Read as | Reading | From | Until | Version installed |
|---|---|---|---|---|
| this account | on | 2026-11-13T02:10:04Z | 2026-11-13T03:40:04Z | v2.1.323 |
| anonymous | on | 2026-11-12T21:05:04Z | 2026-11-13T03:40:04Z | v2.1.322 to v2.1.323 |
| this account | no longer carried | 2026-11-13T00:05:05Z | 2026-11-13T00:05:05Z | v2.1.323 |
| this account | on | 2026-11-12T23:20:05Z | 2026-11-12T23:55:05Z | v2.1.323 |
| this account | no longer carried | 2026-11-12T22:25:04Z | 2026-11-12T22:25:04Z | v2.1.323 |
| this account | on | 2026-11-12T22:10:05Z | 2026-11-12T22:20:07Z | v2.1.322 to v2.1.323 |
| this account | off | 2026-11-10T18:40:05Z | 2026-11-12T21:35:04Z | v2.1.322 |
| anonymous | off | 2026-11-10T16:30:07Z | 2026-11-12T20:35:04Z | v2.1.322 |
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
1The earliest release whose published evidence quoted tengu_fizzy_wren was v2.1.323, 12 Nov 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
0The miner has never read a build containing this name. It is here because a changelog entry of ours names it, which is evidence that it existed and not evidence of which releases carried it. The inventory starts at v2.1.138 and everything older than that was never mined.
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.