What plugin would you build if writing it once worked across Claude Code, Codex, OpenCode, and Pi?

[espetro]

I keep asking myself this. Some candidates I have been mulling:

• Conventional commits — slash command that drafts commit messages from staged diff
• PR description generator — slash command that writes PR titles + bodies from branch diff
• Test runner — hook that auto-runs the right test command per file type before commit
• Dependency auditor — slash command that flags outdated/vulnerable deps
• Docstring synthesizer — slash command that fills missing docstrings from function bodies

What is the plugin you would write if writing it once was enough? Curious what pain points I am missing.