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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 v2.1.238

Model and effort switch warning now checks whether the cache is actually warm

You'll notice
Useful3 Signal2
Models

The warm-cache warning when switching model or effort only appears when a warm cache actually exists.

What

The confirmation shown when switching model or reasoning effort now depends on whether prompt caching is on for the current model and the last main-thread request is still within the cache lifetime, rather than a stored flag. The warning about discarding a warm cache appears only when there is one.

Details
  • Setting DISABLE_PROMPT_CACHING (or the per-model equivalents) suppresses the warning entirely, since caching is off.
Evidence

repl_main_thread

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 v2.1.238 →