Source Intelligence
Follow Discord
Sweep 28 Aug 2026 · 00:00Z Build v2.1.250 478 read Stable v2.1.236 Latest v2.1.250 Next v2.1.250 Feeds RSS JSON llms.txt

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_prompt_cache_diagnostics

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

Cache diagnostics know when the baseline came from disk and skip misleading difference reports.

Not Anthropic's. This is the line from the earliest changelog entry here that named it, v2.1.232.

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 — bool:false

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

ReleaseResolvedThis accountAnonymousCompiled default
v2.1.246 On for this account, and not off by default on on not a boolean we can read
v2.1.232 read on another version On for this account, and not off by default on on on

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.

Changelog entries naming it

  1. v2.1.246Prompt and context experiment renamed to tengu_expressive_whistle, four other switches retired

    A prompt-and-context experiment switch was renamed and four other switches disappeared entirely.

    gate cited by this entry

  2. v2.1.232Cache-break diagnostics note when the baseline was loaded from disk

    Cache diagnostics know when the baseline came from disk and skip misleading difference reports.

    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_prompt_cache, up to twelve of them.

tengu_prompt_cache_1h_configWhether a one-hour prompt cache is allowed can now be overridden per agent and can ignore overage. 2.1.138 tengu_prompt_cache_breakCache diagnostics know when the baseline came from disk and skip misleading difference reports. never mined tengu_prompt_cache_diagnosis_receivedMCP server error lines are escaped before display, plus minor telemetry and version-string cleanups. never mined

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.