Fix environment variables not updating in tmux sessions

[Copilot]

When starting tmux from a vfox-activated shell, environment variables like GOPATH were not updated because tmux inherits __VFOX_PID from the parent shell, causing vfox to skip re-initialization despite running in a different process.

Changes

• bash/zsh hooks: Check PID match instead of just existence
  • Old: if [[ -z "$__VFOX_PID" || -z "$__VFOX_SHELL" ]]
  • New: if [[ -z "$__VFOX_PID" || "$__VFOX_PID" != "$$" || "$__VFOX_SHELL" != "bash|zsh" ]]

This ensures re-initialization when:

• PID differs (tmux, new shell sessions)
• Shell type changes (switching between bash/zsh)
• First activation (variables unset)

Note: Fish shell unchanged - uses process-event-based hooks that don't exhibit this issue.

Original prompt

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This section details on the original issue you should resolve

<issue_title>[BUG]: vfox golang env GOPATH in tmux not working</issue_title>
<issue_description>Version
The version you are currently using
OS
macOS、Linux

Describe the bug
GOPATH in tmux not working

Screenshots[optional]

❯ echo $GOROOT;echo $GOPATH
/home/vb/.version-fox/temp/1724860800-47300/golang
/home/vb/.version-fox/temp/1724860800-47300/golang/packages
❯ tmux
❯ echo $GOROOT;echo $GOPATH
/home/vb/.version-fox/temp/1724860800-47300/golang
/home/vb/go

Then I try to source ~/.zshrc
But it still doesn't work

❯ source ~/.zshrc
❯ echo $GOROOT;echo $GOPATH
/home/vb/.version-fox/temp/1724860800-47300/golang
/home/vb/go

❯ vfox activate zsh

if [[ -z "$__VFOX_PID" ]]; then
  export GOROOT=$'/home/vb/.version-fox/temp/1724860800-47300/golang';export GOPATH=$'/home/vb/.version-fox/temp/1724860800-47300/golang/packages';export __VFOX_SHELL=$'zsh';export PATH=$'/home/vb/.version-fox/temp/1724860800-47300/golang/bin:/home/vb/.version-fox/temp/1724860800-47300/golang/packages/bin:/home/vb/.local/share/zinit/polaris/bin:/usr/local/bin:/usr/bin:/bin:/usr/games:/home/vb/go/bin';export __VFOX_CURTMPPATH=$'/home/vb/.version-fox/temp/1724860800-47300';

  export __VFOX_PID=$$;

  _vfox_hook() {
    trap -- '' SIGINT;
    eval "$("/usr/local/bin/vfox" env -s zsh)";
    trap - SIGINT;
  }
  typeset -ag precmd_functions;
  if [[ -z "${precmd_functions[(r)_vfox_hook]+1}" ]]; then
    precmd_functions=( _vfox_hook ${precmd_functions[@]} )
  fi
  typeset -ag chpwd_functions;
  if [[ -z "${chpwd_functions[(r)_vfox_hook]+1}" ]]; then
    chpwd_functions=( _vfox_hook ${chpwd_functions[@]} )
  fi

  trap 'vfox env --cleanup' EXIT
fi


❯ eval "$(vfox activate zsh)"

vb@debian ~
❯ echo $GOROOT;echo $GOPATH
/home/vb/.version-fox/temp/1724860800-47300/golang
/home/vb/go

</issue_description>

Comments on the Issue (you are @copilot in this section)

@jan-bar Create a new terminal and immediately execute: `env | grep __VFOX`. Let me see if it is consistent with the problem I encountered

• Fixes [BUG]: vfox golang env GOPATH in tmux not working #342

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