[BUG] The current implementation of Zsh completion installation may have unexpected side effects in some shell configurations

[j-g00da]

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Example Code

N/A

Description

The current implementation of Zsh completion installation adds following lines to .zshrc.

fpath+=~/.zfunc; autoload -Uz compinit; compinit
zstyle ':completion:*' menu select

This has some unintended consequences, especially if user uses a shell framework such as Oh My Zsh.

1. There is a noticable slowdown in Zsh startup in some configurations, including OMZ.
   This happens because OMZ runs compinit and caches it ($ZSH/oh-my-zsh.sh file sourced in .zshrc), then fpath is modified (this invalidates the cache) and compinit runs again, but now takes more time. This problem is not exclusive to OMZ and can happen in other Zsh configurations.
2. This can probably break some other installed completions (untested)
   Source 1:

   I think doing a second compinit after OMZ is loaded will break non-autoloaded completion definitions.

   Source 2:

   Many Zsh frameworks & plugin managers include a call to compinit on startup. Calling compinit more than once increases startup time significantly and erases completion functions added programmatically. You might want to make your users aware of this, to save yourself needless bug reports.

3. zstyle ':completion:*' menu select changes completion style for all CLI programs run from Zsh.
   This was actually acknowledged in the comment

   # TODO: consider setting the style only for the current program
   # style_line = f"zstyle ':completion:*:*:{prog_name}:*' menu select"
   

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Additional Issues with install_zsh Function:

1. It assumes $HOME as a location of .zshrc, this is not always true: [BUG] typer doesn't respect ZDOTDIR env var when adding autocompletion for zsh  #171 Almost fixed in: Support ZDOTDIR in zsh completion #870.
2. It uses naive checks that leave room for edge cases, eg.: if "zstyle" not in zshrc_content.
3. .zfunc is not a standard place for zsh completion functions - this clutters home directory.
4. Modifying .zshrc can probably be avoided.

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I’m opening this discussion to request permission to create an issue and contribute fixes.

Operating System

macOS

Operating System Details

No response

Typer Version

0.15.1

Python Version

3.13.1

Additional Context

This bug was found during research for implementation of Zsh completions in duty: pawamoy/duty#34. During discussion there, an idea was born for astral-sh/uv#11354 and pypa/pipx#1604.