What probably matters to youSection of the release
What
A system turn is an instruction from Claude Code to the model, placed partway through a conversation rather than only at its start. The environment variable CLAUDE_CODE_FORCE_MID_CONVERSATION_SYSTEM can already force these turns on. A setting for each model, named mid_conv_system, can now force them on too.
The override now also applies when Claude Code first sets the format it uses to send the conversation to the model. If either the environment variable or the model setting is present, system turns stay on even when the saved starting record says they are off. Claude Code also records whether system turns were forced this way.
Why
This controls the format of the requests sent to the model. In practice, setting CLAUDE_CODE_FORCE_MID_CONVERSATION_SYSTEM now overrides the stored starting choice as well.
Something disagreesSomething we can check disagrees with this entry, or the writer said they could not settle it.
The writer flagged doubtOnly one extra use of the environment variable is confirmed, so this may be existing code that moved rather than new behaviour.
