per directory zsh config

Put this lines in your .zshrc file

function chpwd() {
  if [ -r $PWD/.zsh_config ]; then
    source $PWD/.zsh_config
  else
    source $HOME/.zshrc
  fi
}

With that now you can make .zsh_config file for each directory you want, and when you cd to that directory, zsh will read the .zsh_config file and use any configuration found in there. So for example if I have this .zsh_config in $HOME/rails_app:

alias rc='./script/rails c'

Now everytime I cd into $HOME/rails_app I will have rc command to open a rails console, and when I cd into other directory that doesn't have .zsh_config file zsh will use the original config file (or read .zsh_config file if it's found in the new directory).