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Claude Code v2.1.239 ·

New modelSettings config key holds per-model effort

A new modelSettings config key stores an effort level per model, from low to xhigh.

Use it now Notable New Features
JSON All of v2.1.239
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4Useful: my rating, 1 to 5
4Signal: worth watching, 1 to 5
InternalsArea: what it touches
New FeaturesKind: in v2.1.239,
What probably matters to youSection of the release
What

Global config gained a modelSettings map keyed by model name, where each entry can carry an effortLevel of low, medium, high or xhigh. The existing single saved effort level stays alongside it.

Details
  • Keys are canonical model names; prototype-polluting keys such as __proto__ are stripped on read.
  • Values that do not parse fall back to undefined rather than erroring.
  • The schema accepts the key in this build; what writes it is a separate question.
Evidence

Per-model settings keyed by canonical model name.

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

Read from
Names in the bundlemodelSettingseffortLevelxhigh
Since it was published

The entry above is what we published on the day. These lines were added later, as Anthropic's own pages caught up, and they sit beside the original rather than replacing it.

Confirmed since Anthropic's documentation has since written up effortLevel, on Configuration reference. The effort level the default model (the first `inferenceModels` entry, or the first model your endpoint returns under discovery) starts at in Chat, Cowork and Code, in place of Anthropic's recommended level for that model: one of `low`, `m… third-party/claude-desktop/configuration see the edit
Confirmed since Anthropic's documentation has since written up xhigh, on Model configuration. * The model doesn't support `xhigh` effort model-config see the edit
Added since A small documentation edit on CLI reference touched a line naming modelSettings after this was published. | `--effort` | Set the [effort level](/docs/en/model-config#adjust-effort-level) for the current session. Options: `low`, `medium`, `high`, `xhigh`, `max`, or `ultracode`. Available levels depend on the model. `ultracode` requests `xhigh` … cli-reference see the edit
Added since A small documentation edit on Agent SDK reference - TypeScript touched a line naming xhigh after this was published. `effortLevel` accepts an [effort level](/docs/en/model-config#adjust-effort-level) name. It also accepts `"ultracode"`, which requests `xhigh` effort with [ultracode](/docs/en/workflows#let-claude-decide-with-ultracode) on. `applyFlagSetti… agent-sdk/typescript see the edit
Added since A small documentation edit on Agent SDK reference - TypeScript touched a line naming effortLevel after this was published. `effortLevel` accepts an [effort level](/docs/en/model-config#adjust-effort-level) name. It also accepts `"ultracode"`, which requests `xhigh` effort with [ultracode](/docs/en/workflows#let-claude-decide-with-ultracode) on. `applyFlagSetti… agent-sdk/typescript see the edit
How sure we are
Two sources agreeTwo things we can check say the same as this entry.
Anthropic's documentation agreesA small documentation edit on Agent SDK reference - TypeScript touched a line naming effortLevel after this was published.
The name it cites is new in this buildNew in this build: modelSettings

See this entry in the whole of v2.1.239 →

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