Function syncular_client_command 

#[unsafe(no_mangle)]
pub extern "C" fn syncular_client_command(
    handle: *mut Handle,
    command_json: *const c_char,
) -> *mut c_char

Run one JSON command ({"method","params"}) against the client. Returns a freshly-allocated {"result"|"error"} JSON string the caller frees with syncular_free_string. Returns null only on a null handle.

Safety

handle must be a live handle from syncular_client_new; command_json a valid NUL-terminated UTF-8 C string.