I can't deal with first party anthropic clients because they're not open source. Think about how long it took them to relent on supporting AGENTS.md. Being subject to that kind of hostile imposition is a non starter for me when such excellent open source alternatives exist.

I don't use the first party codex clients because they don't offer the same level of control as Pi. I just can't live without `/tree` and the ability to use headless neovim as my prompt editor. Maybe there's a decent plug-in system for codex at this point but it would have to actually be superior to pi's for me to consider switching, since I prefer to keep a single harness for all my agents (both OAI's and actually open AI like Kimi), but I might if the product were compelling enough.

As for well-designed open-source third-party harnesses; I'm not at all opposed to GUI. I used conductor and liked it, but again was disappointed by the level of control it provided. And once you get comfortable enough in tmux, it's actually pretty difficult to get a better user experience from a GUI. For instance, scrolling and using the clipboard in tmux are both far more powerful and convenient for me than dragging the mouse or spinning it's wheel. But I anticipate there being a really excellent GUI harness at some point!