tengu_umber_lattice
A Claude Code feature flag, read out of the shipped bundle. It was in the build from v2.1.224 and was gone by v2.1.267.
Published artifacts can gain a document database Claude reads and writes, off unless you set the env var.
Not Anthropic's. This is the line from the earliest changelog entry here that named it, v2.1.224.
In the changelogs
8Releases whose published page names tengu_umber_lattice.
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v2.1.267
Artifact feature: env var and gate renamed (artifact DB -> artifact type catalog)
The artifact type catalog's override variable and internal flag were renamed
gate cited by this entry, found in this entry's text
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v2.1.265
Artifact DB str_replace action is built but flagged off
A new str_replace write action for the artifact database is built but not yet exposed to users
gate cited by this entry
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v2.1.265
Artifact-database write gains a string-replace op and optimistic versioning
Artifact database writes gain a string-replace operation and version-checked writes
gate cited by this entry
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v2.1.257
Artifact database write/read tool respects the read-block setting
Artifact database reads and writes now honor the setting that confines file access to your working directories.
gate cited by this entry
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v2.1.228
Artifact database reports a rejected session credential
A rejected artifact credential now reports a distinct "report this" outcome rather than a permission answer.
gate cited by this entry, found in this entry's text
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v2.1.224
Artifact tool gains a document database, off by default
Published artifacts can gain a document database Claude reads and writes, off unless you set the env var.
gate cited by this entry, found in this entry's text
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v2.1.224
Permission prompts for artifact database access
Artifact database access asks permission first, with reads and writes scoped differently.
gate cited by this entry, found in this entry's text
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v2.1.224
Artifact database access must be declared when publishing
An artifact must declare database capability when published, or database calls fail and ask you to republish.
gate cited by this entry, found in this entry's text
Gate readings
5| Release | Resolved | This account | Anonymous | Compiled default |
|---|---|---|---|---|
| v2.1.267 | On for this account, and not off by default | on | on | not a boolean we can read |
| v2.1.265 | Not enough to say | no value returned | on | off |
| v2.1.257 read on another version | Off in both readings | off | off | off |
| v2.1.228 read on another version | Off by default, switched on for this account | on | on | off |
| v2.1.224 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
14| Read as | Reading | From | Until | Version installed |
|---|---|---|---|---|
| anonymous | on | 2026-10-17T05:30:04Z | 2026-10-23T15:45:04Z | v2.1.302 to v2.1.309 |
| this account | on | 2026-09-10T21:47:12Z | 2026-10-23T15:45:04Z | 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 | 2026-09-01T19:45:06Z | 2026-10-17T05:10:04Z | v2.1.257 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 | 2026-09-01T20:10:05Z | 2026-09-06T01:55:04Z | v2.1.257 to v2.1.261 |
| this account | off | 2026-08-14T22:10:05Z | 2026-09-01T19:45:06Z | v2.1.232 to v2.1.257 |
| anonymous | off | 2026-08-19T04:25:04Z | 2026-09-01T19:40:05Z | v2.1.233 to v2.1.257 |
| anonymous | no longer carried | 2026-08-19T04:20:14Z | 2026-08-19T04:20:14Z | v2.1.233 |
| anonymous | off | 2026-08-14T22:10:05Z | 2026-08-19T03:45:04Z | v2.1.232 to v2.1.233 |
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_umber_lattice was v2.1.257, 1 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
2Build by build
74One 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.