Constant INTERACTIVE_SELF_TERMINATE_INSTRUCTION 

pub const INTERACTIVE_SELF_TERMINATE_INSTRUCTION: &str = "\n\n\
    When you are finished with this session, exit cleanly by running \
    `zig self terminate` in your shell. Do not wait for the user to close \
    the session — self-terminate so the workflow can proceed to the next step.";

Instruction appended to interactive agents’ system prompts so they know how to exit the session when they finish. Exposed for tests in run_tests.rs and used from run::build_agent_config.