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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.

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Claude Code v2.1.242

Prompt snippet for cutting Opus 5's time to first token

You'll notice
Useful3 Signal4
Model Docs

Model guidance adds a one-line instruction to cut Opus 5's delay before its first visible output.

What

The bundled model guidance adds a note that Opus 5 sometimes thinks before emitting its first visible block, which raises the delay before anything appears in chat and voice, along with a one-line system instruction to reduce it.

Details
  • The suggested line is Latency-sensitive; begin your visible answer immediately.
  • The advice is to apply it only where first-token latency is visible to a person, not everywhere.
  • It also appears as a new tuning item in the Opus 5 checklist.
Evidence

Latency-sensitive; begin your visible answer immediately.

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 v2.1.242 →