Per-terminal Zsh history: use a separate HISTFILE for each terminal app (VS Code, iTerm, etc.) while keeping a common history for Apple Terminal and Ghostty on Linux/WSL.

zsh-per-app-history

set_app_history() {
  local app=${TERM_PROGRAM:-Apple_Terminal}
  local default_histfile="$HOME/.zsh_history"

  # Terminals that should use the shared/default history file
  local -a SHARED_HISTORY_TERMINALS=(
    Apple_Terminal
    iTerm.app
    Ghostty
  )

  local use_shared=false

  # If running inside tmux, always share history
  if [[ -n "$TMUX" ]] || [[ "$app" == "tmux" ]]; then
    use_shared=true
  else
    # Check if $app is in SHARED_HISTORY_TERMINALS
    local t
    for t in "${SHARED_HISTORY_TERMINALS[@]}"; do
      if [[ "$app" == "$t" ]]; then
        use_shared=true
        break
      fi
    done
  fi

  if [[ "$use_shared" == true ]]; then
    HISTFILE="$default_histfile"
  else
    # Everything else → per-app history
    local safe_app=${app//[^A-Za-z0-9]/_}
    HISTFILE="$HOME/.zsh_history_${safe_app}"
  fi

  export HISTFILE
}

set_app_history