What probably matters to youSection of the release
What
A cache breakpoint is a marker that tells the API which part of a request it can reuse from an earlier one. When the environment variable CLAUDE_CODE_SIMULATE_PROXY_USAGE is set, Claude Code now also leaves these markers off system messages sent to the API. Before, only an existing check controlled that.
The step that places these markers also now accepts a message from which the conversation branches off.
Why
This mostly matters to people testing how Claude Code behaves behind a proxy.
