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Sweep 28 Aug 2026 · 00:00Z Build v2.1.250 478 read Stable v2.1.236 Latest v2.1.250 Next v2.1.251 Feeds RSS JSON llms.txt
Reading a new release v2.1.251 Analysing changes · 2/5 Sorting the findings · 1/4 steps 470 findings $18.91 so far

DisclaimerUnofficial, and not affiliated with Anthropic. Nearly all of this is read straight out of what ships: npm bundles, captured prompts, published docs. Anthropic's own notes go in verbatim, marked as theirs. The rest is my reading, and every entry carries the strings behind it. If one looks wrong, vote it down and say why.

Reference / Feature flags

tengu_kairos_brief_config

A Claude Code feature flag, read out of the shipped bundle. It has been in the build since v2.1.138, including the newest one read.

What it is

/brief is hidden by server config, but brief mode still works via an environment variable.

Not Anthropic's. This is the line from the earliest changelog entry here that named it, v2.1.248.

Presence across releases

ReleasesReadingDeclared typeDefault
2.1.245 – 2.1.250 5 releases never mined — —
2.1.138 – 2.1.243 95 releases in the build — unknown

A row reading never mined is a release with no archived bundle behind it. Nothing was read out of it, so nothing here says whether the name was in it. A declared type or a default is only ever what that release's own bundle stated.

Gate readings

No 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.

Changelog entries naming it

  1. v2.1.248/brief is hidden unless the server enables it

    /brief is hidden by server config, but brief mode still works via an environment variable.

    gate cited by this entry

Documentation pages

None of Anthropic's documentation pages this site has a copy of carries this name.

Names beside it

Every feature flag in the inventory starting tengu_kairos_brief, up to twelve of them.

tengu_kairos_briefNo description from anybody. 2.1.138 tengu_kairos_brief_stop_hook_textNo description from anybody. 2.1.138

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.