tengu_iridescent_gem
A Claude Code feature flag, read out of the shipped bundle. It has been in the build since v2.1.261, including the newest one read.
New sampled telemetry records detailed hashes around cache-prefix breaks.
Not Anthropic's. This is the line from the earliest changelog entry here that named it, v2.1.261.
In the changelogs
2Releases whose published page names tengu_iridescent_gem.
-
v2.1.261
New telemetry: prefix-break diagnostics with sampled hashing
New sampled telemetry records detailed hashes around cache-prefix breaks.
gate cited by this entry
-
v2.1.261
Detailed prompt-cache-break diagnostics (message0 shape/section diffing) sampled off by default
Detailed prompt-cache-break diffing telemetry exists but is sampled at zero by default.
found in this entry's text, named in this entry, gate cited by this entry
Gate readings
0No release here has a gate table behind it for this flag. Most published releases have none at all: the readings exist only for versions the pipeline captured flag state on.
Flag server, over time
18| Read as | Reading | From | Until | Version installed |
|---|---|---|---|---|
| this account | 0.01 | 2026-11-02T13:05:04Z | 2026-11-12T09:35:04Z | v2.1.316 to v2.1.322 |
| anonymous | 0.01 | 2026-10-17T05:30:04Z | 2026-11-12T09:35:04Z | v2.1.302 to v2.1.322 |
| this account | null | 2026-11-02T12:55:05Z | 2026-11-02T12:55:05Z | v2.1.316 |
| this account | 0.01 | 2026-11-01T20:45:05Z | 2026-11-02T12:40:07Z | v2.1.316 |
| this account | null | 2026-11-01T20:40:05Z | 2026-11-01T20:40:05Z | v2.1.316 |
| this account | 0.01 | 2026-11-01T20:25:04Z | 2026-11-01T20:30:06Z | v2.1.316 |
| this account | null | 2026-11-01T20:20:05Z | 2026-11-01T20:20:05Z | v2.1.316 |
| this account | 0.01 | 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 | 0.01 | 2026-09-05T05:20:04Z | 2026-10-17T05:10:04Z | v2.1.261 to v2.1.302 |
| this account | null | 2026-10-07T17:59:34Z | 2026-10-07T17:59:34Z | v2.1.293 |
| this account | 0.01 | 2026-09-10T21:47:12Z | 2026-10-07T17:10:05Z | v2.1.268 to v2.1.292 |
| this account | no longer carried | 2026-09-10T21:46:45Z | 2026-09-10T21:46:45Z | v2.1.268 |
| this account | 0.01 | 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 | 0.01 | 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 | 0.01 | 2026-09-05T07:25:04Z | 2026-09-06T01:55:04Z | 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
1The earliest release whose published evidence quoted tengu_iridescent_gem was v2.1.261, 4 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
5Build by build
55One 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.