tengu_carved_slate
A Claude Code feature flag, read out of the shipped bundle. It was in the build from v2.1.251 and was gone by v2.1.268.
Claude Code now only re-sends changed CLAUDE.md/instruction files instead of the whole block each turn, saving tokens.
Not Anthropic's. This is the line from the earliest changelog entry here that named it, v2.1.252.
In the changelogs
7Releases whose published page names tengu_carved_slate.
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v2.1.265
Static system prompt mode (tengu_carved_slate) strips dynamic content from agent prompts when on
A new staticSystemPromptEnabled flag can strip dynamic content from agent system prompts
gate cited by this entry, found in this entry's text
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v2.1.252
Incremental CLAUDE.md / tool-description context diffing ('instructions' attachments)
Claude Code now only re-sends changed CLAUDE.md/instruction files instead of the whole block each turn, saving tokens.
gate cited by this entry
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v2.1.252
New "instructionFiles" context channel, gated behind carved-slate flag
A separate instruction-files context channel exists but is off by default, part of a static system prompt rework.
found in this entry's text, gate cited by this entry
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v2.1.252
Context/cost breakdown now counts tool descriptions from a recorded prompt snapshot
Context/cost breakdowns like /context now reuse the exact tool description text actually sent, for accuracy.
gate cited by this entry
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v2.1.252
Scratchpad directory: a new per-session temp-file location announced to the model
Claude may soon be told to use a per-session scratchpad directory for temp files instead of /tmp.
gate cited by this entry
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v2.1.252
Scratchpad directory tracked in environment-change diffs and telemetry schema
The scratchpad directory is now tracked in environment-change diffs and telemetry like other environment fields.
gate cited by this entry
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v2.1.252
claudeMd now explicitly emitted as empty string under carved-slate mode
Under an experimental mode, empty CLAUDE.md content is now sent as an explicit empty string to keep prompt caching stable.
gate cited by this entry
Gate readings
3| Release | Resolved | This account | Anonymous | Compiled default |
|---|---|---|---|---|
| v2.1.265 | Not enough to say | no value returned | on | not a boolean we can read |
| v2.1.252 | Off in both readings | off | off | not a boolean we can read |
| v2.1.251 | Off in both readings | off | off | 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
12| Read as | Reading | From | Until | Version installed |
|---|---|---|---|---|
| anonymous | on | 2026-10-17T05:30:04Z | 2026-11-12T09:10:04Z | v2.1.302 to v2.1.322 |
| this account | on | 2026-09-10T21:47:12Z | 2026-11-12T09:10:04Z | v2.1.268 to v2.1.322 |
| anonymous | no longer carried | 2026-10-17T05:25:57Z | 2026-10-17T05:25:57Z | v2.1.302 |
| anonymous | on | 2026-09-08T20:34:58Z | 2026-10-17T05:10:04Z | v2.1.265 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 | 2026-09-08T20:55:05Z | 2026-09-10T17:40:05Z | v2.1.265 to v2.1.267 |
| this account | off | 2026-09-08T20:36:15Z | 2026-09-08T20:45:05Z | v2.1.263 to v2.1.265 |
| this account | no longer carried | 2026-09-08T20:34:58Z | 2026-09-08T20:34:58Z | v2.1.265 |
| this account | off | 2026-09-06T02:40:05Z | 2026-09-08T18:45:05Z | v2.1.261 to v2.1.263 |
| anonymous | off | 2026-08-27T19:55:04Z | 2026-09-08T18:45:05Z | v2.1.246 to v2.1.263 |
| this account | no longer carried | 2026-09-06T02:36:19Z | 2026-09-06T02:36:19Z | v2.1.263 |
| this account | off | 2026-08-27T22:35:37Z | 2026-09-06T01:55:04Z | v2.1.246 to v2.1.261 |
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
0No release's published evidence quotes this name. The ledger indexes the Evidence lines of every changelog on this site, so this says nobody here has ever quoted it; it says nothing about how old the name is.
Presence across releases
2Build by build
61One 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.