tengu_cosmic_shore
A Claude Code feature flag, read out of the shipped bundle. It has been in the build since v2.1.285, including the newest one read.
Default true. When on, a shell command running in the background is stopped once it passes a deadline, capped at 2 hours (or BASH_MAX_TIMEOUT_MS if larger): a command started with run_in_background uses its timeout if given, and otherwise, or when a command is moved to the background later, the deadline is 30 minutes (or BASH_DEFAULT_TIMEOUT_MS if larger); the message telling Claude a command moved to the background can then say when it will be stopped. When off, or when the background deadline is disabled for the session, backgrounded commands get no such deadline, and commands started by Monitor never get it.
Not Anthropic's. Written by Claude Opus 5.5 from reading the v2.1.286 bundle, and it can be wrong.
In the changelogs
0No changelog entry here has ever named it. That is a statement about what has been written, not about the name: it has been in the build since v2.1.285 without anybody writing a line about it.
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 | 2026-09-29T04:05:04Z | 2026-10-09T01:05:07Z | v2.1.284 to v2.1.295 |
| anonymous | on | 2026-09-29T04:00:06Z | 2026-10-09T01:05:07Z | v2.1.284 to v2.1.295 |
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
0No release's published evidence quotes this name. The ledger indexes the Evidence lines of every changelog on this site, so this says nobody here has ever quoted it; it says nothing about how old the name is.
Presence across releases
1Build by build
11One 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.