What it is
New system-prompt text explains the sandbox's boundaries to the model, gated behind an unread flag
Not Anthropic's. This is the line from the earliest changelog entry here that named it, v2.1.268.
Presence across releases
0The miner has never read a build containing this name. It is here because a changelog entry of ours names it, which is evidence that it existed and not evidence of which releases carried it. The inventory starts at v2.1.138 and everything older than that was never mined.
First cited
1The earliest release whose published evidence quoted tengu_elegant_ocean was v2.1.268, 10 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 |
|---|---|---|---|---|
| this account | on | 2026-09-13T17:55:04Z | 2026-09-23T08:55:05Z | v2.1.270 to v2.1.280 |
| anonymous | on | 2026-09-13T16:30:05Z | 2026-09-23T08:55:05Z | v2.1.270 to v2.1.280 |
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_elegant, 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.