Source Intelligence

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.

All of v2.1.246 Home All releases olderv2.1.245 v2.1.247newer
Claude Code v2.1.246

Prompt and context experiment renamed to tengu_expressive_whistle, four other switches retired

Under the hood
Useful1 Signal0
Internals

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

The guarded prompt and context work now reads tengu_expressive_whistle, off by default, and four older switch names were removed.

Feature flag
tengu_expressive_whistle Not enough to say

Nothing here resolved what this flag was doing on this version, so nothing here should be read as on or off.

This account: no value returned · anonymous baseline: no value returned · compiled default in v2.1.246: on

tengu_saffron_anchor On for this account, and not off by default

The flag server returned on for the one account this site reads, and nothing in this release compiles it off by default. The compiled default is shown below, and says which it is when we cannot read one: a fifth of gates compile in a string or a number rather than on or off, and most published releases have no gate table behind them at all. No client can see what the server returns for your account.

This account: on · anonymous baseline: on · compiled default in v2.1.246: not a boolean we can read

tengu_prompt_cache_diagnostics On for this account, and not off by default

The flag server returned on for the one account this site reads, and nothing in this release compiles it off by default. The compiled default is shown below, and says which it is when we cannot read one: a fifth of gates compile in a string or a number rather than on or off, and most published releases have no gate table behind them at all. No client can see what the server returns for your account.

This account: on · anonymous baseline: on · compiled default in v2.1.246: not a boolean we can read

tengu_dazzling_floyd Gate removed from the code

This release deleted the gate from the code while it was still reading on for the account this site reads, so the code path no longer asks a flag before running.

This account: on · anonymous baseline: on · compiled default in v2.1.246: not a boolean we can read

tengu_cobalt_plinth_reader_persist On for this account, and not off by default

The flag server returned on for the one account this site reads, and nothing in this release compiles it off by default. The compiled default is shown below, and says which it is when we cannot read one: a fifth of gates compile in a string or a number rather than on or off, and most published releases have no gate table behind them at all. No client can see what the server returns for your account.

This account: on · anonymous baseline: on · compiled default in v2.1.246: not a boolean we can read

Read once, for one account on one subscription tier, against v2.1.246. It isn't a statement about your account. What a flag value here can and cannot tell you

What

A remotely controlled switch guarding unreleased prompt and context work now goes by tengu_expressive_whistle instead of tengu_saffron_anchor, keeping the same reader function behind the new name. It defaults to off when the server sends no value, and the code it guards returns immediately while off, so nothing changes for you in this build. Four unrelated switch names that existed in v2.1.245 are gone from this build along with the functions that read them, meaning whatever they controlled is now either permanently on or removed.

Details
  • tengu_saffron_anchor no longer appears anywhere in the build; only the new name is read.
  • With the switch unset or off, the guarded prompt and context path exits at once and takes no other action.
  • The four fully retired switches are tengu_prompt_cache_diagnostics, which guarded prompt-cache diagnostics, tengu_dazzling_floyd, which was read as a negated gate so that its absence enabled the behaviour, tengu_cobalt_plinth_reader_persist, and tengu_bg_retire_grace_bridged_min, which supplied a 480 minute grace period converted to milliseconds.
  • No user-facing setting, command-line flag or environment variable is attached to any of these; they are server-controlled experiment switches only.
Evidence

tengu_expressive_whistle, tengu_bg_retire_grace_bridged_min

Strings lifted out of the shipped bundle, so the claim above can be checked against them.

See this entry in the whole of v2.1.246 →