You'll notice
SDK control commands like get_context_usage no longer need a special environment variable to be recognized
What
Control-command message types used by the SDK and bridge integrations, including mcp_status, get_context_usage, list_models, mcp_toggle, and background_tasks, were previously only recognized when the environment variable CLAUDE_CODE_LARCH_CISTERN was set along with a flag. Now they are recognized unconditionally, just by checking whether the command type is in the known list.
Why
This removes a gate that previously restricted these SDK control commands, so they now work without needing that special environment variable set.