tengu_swift_lynx
A Claude Code feature flag, read out of the shipped bundle. It was in the build from v2.1.275 and was gone by v2.1.319.
A hidden new tool lets Claude open the page for a startup promotional offer
Not Anthropic's. This is the line from the earliest changelog entry here that named it, v2.1.275.
In the changelogs
5Releases whose published page names tengu_swift_lynx.
-
v2.1.296
VS Code extension no longer receives the promo claim link setting at start-up
The remote setting behind promo claim links is no longer passed to the VS Code extension when it starts, but is still read elsewhere
gate cited by this entry
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v2.1.283
Promo claim link can include your organization
Opening a promo claim page can now add your organization's ID to the link, when a remote setting switches that on
gate cited by this entry
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v2.1.275
Hidden 'claim-credit' local tool tied to a startup promo
A hidden new tool lets Claude open the page for a startup promotional offer
gate cited by this entry, found in this entry's text
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v2.1.275
New "limit wall" promo option added to the rate-limit options menu
Rate-limit menu gains a new promotional "limit wall" option pointing to a claim page
gate cited by this entry
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v2.1.275
New hidden startup-promo command gated behind remote flag tengu_swift_lynx
A hidden command to reopen a startup promo's offer page appears, gated behind tengu_swift_lynx
gate cited by this entry, found in this entry's text, named in this entry
Gate readings
3| Release | Resolved | This account | Anonymous | Compiled default |
|---|---|---|---|---|
| v2.1.296 read on another version | Not enough to say | no value returned | no value returned | not a boolean we can read |
| v2.1.283 read on another version | Not enough to say | no value returned | no value returned | not a boolean we can read |
| v2.1.275 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
4| Read as | Reading | From | Until | Version installed |
|---|---|---|---|---|
| anonymous | null | 2026-10-17T05:30:04Z | 2026-11-06T13:45:04Z | v2.1.302 to v2.1.318 |
| this account | null | 2026-09-23T06:20:05Z | 2026-11-06T13:45:04Z | v2.1.280 to v2.1.318 |
| anonymous | no longer carried | 2026-10-17T05:25:57Z | 2026-10-17T05:25:57Z | v2.1.302 |
| anonymous | null | 2026-09-23T05:35:04Z | 2026-10-17T05:10:04Z | v2.1.280 to v2.1.302 |
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_swift_lynx was v2.1.296, 9 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.
Presence across releases
2Build by build
41One 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.