tengu_slate_lantern_ember
A Claude Code feature flag, read out of the shipped bundle. It has been in the build since v2.1.236, including the newest one read.
Re-armed artifact watches could reuse an existing connection instead of starting over, but the flag is off.
Not Anthropic's. This is the line from the earliest changelog entry here that named it, v2.1.236.
In the changelogs
6Releases whose published page names tengu_slate_lantern_ember.
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v2.1.257
New reconnect-jitter spread for artifact re-arm, gated behind tengu_slate_lantern_ember
Re-arming an artifact watch can add a computed delay to spread reconnect attempts, behind a gate.
found in this entry's text, gate cited by this entry
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v2.1.250
Long-stall backoff band and randomised give-up window for live watches
Stalled watches now wait 2-4 minutes between retries and give up at a random point between 30 and 45 minutes.
named in this entry, gate cited by this entry, found in this entry's text
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v2.1.250
Which stall backoff tier is used depends on the lease-mode flag
Repeat stalls take the long 2-4 minute retry tier because lease mode is off in a stock build.
named in this entry, gate cited by this entry, found in this entry's text
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v2.1.236
Live artifact watches can reuse a subscription instead of re-subscribing
Re-armed artifact watches could reuse an existing connection instead of starting over, but the flag is off.
gate cited by this entry, found in this entry's text
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v2.1.236
New flag tengu_slate_lantern_ember for lease-based artifact auto-replies
One new switch controls both early artifact comment reads and a lease-based auto-reply mode, off by default.
gate cited by this entry, found in this entry's text
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v2.1.236
Early artifact comment read is behind two flags, both off
The early artifact comment read needs two separate switches, both of which default off.
gate cited by this entry, found in this entry's text
Gate readings
3| Release | Resolved | This account | Anonymous | Compiled default |
|---|---|---|---|---|
| v2.1.257 read on another version | Off by default, switched on for this account | on | on | off |
| v2.1.250 | Off by default, switched on for this account | on | on | off |
| v2.1.236 | Off in both readings | off | off | 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
16| Read as | Reading | From | Until | Version installed |
|---|---|---|---|---|
| anonymous | on | 2026-10-17T05:30:04Z | 2026-10-22T23:05:05Z | v2.1.302 to v2.1.309 |
| this account | on | 2026-09-10T21:47:12Z | 2026-10-22T23:05:05Z | v2.1.268 to v2.1.309 |
| anonymous | no longer carried | 2026-10-17T05:25:57Z | 2026-10-17T05:25:57Z | v2.1.302 |
| anonymous | on | 2026-08-21T17:05:13Z | 2026-10-17T05:10:04Z | v2.1.233 to v2.1.302 |
| this account | no longer carried | 2026-09-10T21:46:45Z | 2026-09-10T21:46:45Z | v2.1.268 |
| this account | on | 2026-09-08T20:36:15Z | 2026-09-10T17:40:05Z | v2.1.263 to v2.1.267 |
| this account | no longer carried | 2026-09-08T20:34:58Z | 2026-09-08T20:34:58Z | v2.1.265 |
| this account | on | 2026-09-06T02:40:05Z | 2026-09-08T18:45:05Z | v2.1.261 to v2.1.263 |
| this account | no longer carried | 2026-09-06T02:36:19Z | 2026-09-06T02:36:19Z | v2.1.263 |
| this account | on | 2026-08-21T18:05:04Z | 2026-09-06T01:55:04Z | v2.1.233 to v2.1.261 |
| this account | off | 2026-08-18T19:25:04Z | 2026-08-21T17:05:13Z | v2.1.233 |
| anonymous | off | 2026-08-19T04:25:04Z | 2026-08-21T16:35:14Z | v2.1.233 |
| anonymous | no longer carried | 2026-08-19T04:20:14Z | 2026-08-19T04:20:14Z | v2.1.233 |
| anonymous | off | 2026-08-18T17:30:05Z | 2026-08-19T03:45:04Z | v2.1.233 |
| this account | no longer carried | 2026-08-18T18:55:06Z | 2026-08-18T18:55:06Z | v2.1.233 |
| this account | off | 2026-08-18T18:50:25Z | 2026-08-18T18:50:25Z | v2.1.235 |
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_slate_lantern_ember was v2.1.236, 19 Aug 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
63One 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.