What it is
Claude Code adds three new internal feature gates: typed_koala, zinc_harbor, tranquil_crescent
Not Anthropic's. This is the line from the earliest changelog entry here that named it, v2.1.275.
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_tranquil_crescent was v2.1.275, 17 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
1| Release | Resolved | This account | Anonymous | Compiled default |
|---|---|---|---|---|
| v2.1.275 read on another version | 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
2| Read as | Reading | From | Until | Version installed |
|---|---|---|---|---|
| anonymous | off | 2026-09-16T19:25:04Z | 2026-09-22T05:45:05Z | v2.1.273 to v2.1.278 |
| this account | off | 2026-09-16T19:25:04Z | 2026-09-22T05:45:05Z | v2.1.273 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_tranquil, up to twelve of them.
tengu_tranquil_cloudClaude Code now strips invisible characters like zero-width marks from pasted or typed text before sending it v2.1.277
tengu_tranquil_fernResuming a session that was in plan mode now puts you back in plan mode. v2.1.239
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.