Function run_command_capture 

pub fn run_command_capture(
    command: &str,
    env: &[(String, String)],
    timeout: Duration,
) -> HookTestOutcome

Run command once with env, capturing stdout/stderr and exit code, killing it after timeout. Powers the Settings “Test” button. Like the fire path, no shell is involved — pipes/redirects need an explicit sh -c wrapper. The capture/spawn is the OS shim; the parsing (parse_command) and output handling (truncate_output) are pure and tested, and this whole function is exercised against real commands in the unit tests.