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Sweep 22 Oct 2026 · 21:04Z Build v2.1.309 528 read Stable v2.1.308 Latest v2.1.308 Next v2.1.309 Feeds RSS JSON llms.txt llms-full.txt Unofficial
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Claude Code v2.1.251 ·

Effort cap when thinking is off, tied to a specific model

Some models cap reasoning effort when thinking is off, matched by name or capability.

Under the hood In Development
JSON All of v2.1.251
Under the hoodTier: how much it should matter to you
2Useful: my rating, 1 to 5
5Signal: worth watching, 1 to 5
ModelsArea: what it touches
In DevelopmentKind: in v2.1.251,
What probably matters to youSection of the release
What

A check now identifies models that cap reasoning effort when thinking is disabled, matching claude-opus-5 by name or any model whose capability list carries a thinking_disabled_effort_cap entry.

Details
  • The capability lookup means the cap can apply to future models without a code change.
  • Reworked in this release rather than introduced.
Evidence

claude-opus-5

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 →

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