Source Intelligence
Follow Discord

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 v2.1.219 Home All releases ←olderv2.1.218 v2.1.220newer→
Claude Code v2.1.219

Fast mode advertised on Opus 5 in the environment prompt

Under the hood
Useful1 Signal0
Models

Claude is now told Fast mode applies to Opus 5 as well as earlier models.

What

The two environment-info prompt builders that describe Fast mode now list Opus 5 alongside 4.8 and 4.7, so the model is told Fast mode applies to the new default.

Details
  • Applies to both environment-info prompt builders.
  • No gate; the line is emitted for everyone.
Evidence

It can be toggled with /fast and is available on Opus 5/4.8/4.7.

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

Related

Other releases about the same thing. Found by shared names or similar wording; neither means one caused the other.

See this entry in the whole of v2.1.219 →