I use:
- direnv (https://direnv.net) for project-specific environment variable management and more
- fzf (https://github.com/junegunn/fzf) for rifling through history and finding files quickly.
- z (https://github.com/agkozak/zsh-z) to partial-match on a frequency-weighted directory switch (eg, `z Proj <RET>` will move me to `$HOME/Code/Projects/`.