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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.

← All of v2.1.251 Home All releases ←olderv2.1.250

Claude Code v2.1.251 28 Aug 2026

Model picker can now set an effort level and ultracode

Use it now

Useful4 Signal4

Models Notable

Picking a model can now also set effort level and ultracode for the session.

/model

What

Choosing a model in the picker can now also set a per-session effort level and an "ultracode" flag, when the entry you pick carries a level. The switch runs through a hook-based confirmation that can block it or ask you to confirm first, and the picker no longer writes settings itself; the surrounding code does.

Details

Effort and ultracode are only set for entries that come with a level; plain model entries behave as before.

Evidence

sessionEffort: IC(wr.level)

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

See this entry in the whole of v2.1.251 →