My cd hook was filling Claude's context

My zsh config has a chpwd function that lists the directory after every cd. I like it in my own terminal:

function chpwd() {
  emulate -L zsh
  lh
}

lh is my alias for a long directory listing. Claude Code’s Bash tool loads the same zsh config, so each time the agent ran cd, the listing went into the tool output and used up context. Nothing failed. It was just noise on every directory change.

Claude Code sets CLAUDECODE=1 in the environment of the commands it runs, so the hook can skip the listing when that’s set:

function chpwd() {
  emulate -L zsh
  [[ -n $CLAUDECODE ]] && return
  lh
}

That covers Claude Code. Other agents set their own variables or none at all, so a check for a terminal, [[ -t 1 ]] || return, is the broader version. It skips the listing whenever output isn’t going to a terminal. The same goes for anything else in precmd or chpwd that prints. An agent’s shell runs those hooks too.