What it is
Auto-mode's safety classifier gained a new 'arbiter' mode that can skip some server checks
Not Anthropic's. This is the line from the earliest changelog entry here that named it, v2.1.269.
Presence across releases
1Build by build
10One 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.
First cited
1The earliest release whose published evidence quoted tengu_iridescent_crystal 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 above.
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
2| Read as | Reading | From | Until | Version installed |
|---|---|---|---|---|
| anonymous | off | 2026-09-15T01:05:04Z | 2026-09-22T14:20:05Z | v2.1.272 to v2.1.278 |
| this account | off | 2026-09-15T01:05:04Z | 2026-09-22T14:20:05Z | v2.1.272 to v2.1.278 |
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.
Names beside it
Every feature flag in the inventory starting tengu_iridescent, up to twelve of them.
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.