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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 v2.1.219

Prompt-caching doc rewrites the minimum-cacheable-prompt table and adds cache-preserving escape hatches

You'll notice
Useful3 Signal0
Prompt Caching

Caching docs now list per-model minimums and which request changes keep your cache alive.

What

The per-model minimum table was regrouped and a new table lists which top-level request changes can be made without dropping the cache.

Details
  • Minimums run from 512 tokens for the newest models up to 4096 for Opus 4.6/4.5 and Haiku 4.5, with an explicit note that the value is not monotonic across generations.
  • The old Amazon Bedrock override is documented as removed.
  • Cache-preserving forms: tool definitions via tool_addition/tool_removal (beta), and system-prompt content via a role: "system" message with no beta header.
  • Model switch has no escape hatch.
  • Mid-conversation system-message availability widens from one model to four, with a caveat that sources conflict on Sonnet.
Evidence

The minimum is not monotonic across generations

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 v2.1.219 →