tengu_quiet_heron
A Claude Code feature flag, read out of the shipped bundle. It has been in the build since v2.1.269, including the newest one read.
Continuing a server-side conversation thread can now skip resending the system prompt and tools list, with a fallback if the server disagrees
Not Anthropic's. This is the line from the earliest changelog entry here that named it, v2.1.269.
In the changelogs
2Releases whose published page names tengu_quiet_heron.
-
v2.1.269
'Tether' thread-continuation requests can omit system prompt/tools when continuing, behind two off-by-default flags, with a fingerprint-mismatch circuit breaker
Continuing a server-side conversation thread can now skip resending the system prompt and tools list, with a fallback if the server disagrees
gate cited by this entry, found in this entry's text
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v2.1.269
New heron gate feeds an unused-looking breaker-tripped check
New tengu_quiet_heron gate feeds a breaker-tripped check with no found caller in this code
gate cited by this entry, found in this entry's text
Gate readings
1| Release | Resolved | This account | Anonymous | Compiled default |
|---|---|---|---|---|
| v2.1.269 | Not enough to say | no value returned | no value returned | 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 |
|---|---|---|---|---|
| this account | on | 2026-11-02T13:05:04Z | 2026-11-12T05:55:04Z | v2.1.316 to v2.1.322 |
| anonymous | on | 2026-10-17T05:30:04Z | 2026-11-12T05:55:04Z | v2.1.302 to v2.1.322 |
| this account | off | 2026-11-02T12:55:05Z | 2026-11-02T12:55:05Z | v2.1.316 |
| this account | on | 2026-11-01T20:45:05Z | 2026-11-02T12:40:07Z | v2.1.316 |
| this account | off | 2026-11-01T20:40:05Z | 2026-11-01T20:40:05Z | v2.1.316 |
| this account | on | 2026-11-01T20:25:04Z | 2026-11-01T20:30:06Z | v2.1.316 |
| this account | off | 2026-11-01T20:20:05Z | 2026-11-01T20:20:05Z | v2.1.316 |
| this account | on | 2026-10-07T18:00:12Z | 2026-11-01T19:30:06Z | v2.1.292 to v2.1.316 |
| anonymous | no longer carried | 2026-10-17T05:25:57Z | 2026-10-17T05:25:57Z | v2.1.302 |
| anonymous | on | 2026-09-17T17:15:05Z | 2026-10-17T05:10:04Z | v2.1.274 to v2.1.302 |
| this account | off | 2026-10-07T17:59:34Z | 2026-10-07T17:59:34Z | v2.1.293 |
| this account | on | 2026-09-16T23:35:05Z | 2026-10-07T17:10:05Z | v2.1.273 to v2.1.292 |
| anonymous | off | 2026-09-14T21:05:04Z | 2026-09-17T16:45:05Z | v2.1.270 to v2.1.274 |
| this account | off | 2026-09-16T23:32:48Z | 2026-09-16T23:32:48Z | v2.1.274 |
| this account | on | 2026-09-14T23:35:04Z | 2026-09-16T22:45:04Z | v2.1.271 to v2.1.273 |
| this account | off | 2026-09-14T21:40:04Z | 2026-09-14T23:25:04Z | v2.1.270 to v2.1.271 |
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_quiet_heron was v2.1.269, 11 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
1Build by build
49One 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.