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Reading a new release v2.1.251 Analysing changes · 2/5 Sorting the findings · 1/4 steps 470 findings $18.91 so far

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 v2.1.62

Optimized prompt cache breakpoint placement

What

Cache breakpoints are now applied to the last two messages in a conversation instead of only the final message, potentially improving cache hit rates with the Anthropic API.

Details
  • Previously, only the very last message in a conversation received a cache breakpoint marker
  • Now the last two messages both receive cache breakpoints, increasing the likelihood of cache reuse when new messages are appended
  • The skipCacheWrite flag now only suppresses the breakpoint on the final message, leaving the second-to-last message always cached
  • This is an internal optimization; users may experience marginally faster response times due to improved cache utilization, but no action is required
Evidence

Cache breakpoint logic in message preparation (search for "tengu_api_cache_breakpoints") — K$z() at line ~519758

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

See this entry in the whole of v2.1.62 →