tmux + helix + Alt-[ key not registered

[patrick-kidger]

I've bound Alt-[ and Alt-] for scrolling through Helix buffers (goto_previous_buffer and goto_next_buffer). The fundamental issue I'm getting is that when running under macOS->iTerm2->fish->tmux->Helix, then Alt-[ will not change buffers.

However, curiously:

• Alt-] (scrolling the other way) does work, so Alt is working fine.
• If I rebind goto_previous_buffer to just [ then that works, so [ is working fine.
• When running Helix without tmux, then Alt-[ works, so Helix is working fine.
• When running fish_key_reader within tmux then Alt-[ correctly produces \e\[, so tmux is working fine.

It seems to be specifically some combination of all parts of the stack, along with this one particular key-combo, that results in the key combo getting swallowed.

(For the record in iTerm2->Settings->Profiles->Keys, I have already set Left Option Key: Esc+, as I know that's sometimes the root cause for issues of this nature. Helix version is 23.10 (98ebeeeb); tmux version 3.4.)

This is an odd one, so I thought I'd ask here in case anyone has any ideas?

[phgz]

Have you found a workaround? I have the exact same problem.

[patrick-kidger]

I have not. I ended up needing to redesign my key bindings instead.

[phgz]

I use Wezterm and a workaround I found was to redirect the "Alt-[" in the terminal config to something dummy. And using this dummy mapping in the Helix config. So when I physically press "Alt-[" in Helix it indeed does what I want.

[phgz]

For future readers: In the end I found out that I had to add enable_kitty_keyboard = true (Wezterm) in my terminal configuration. More info here about Enhanced Keyboard Protocol https://github.com/helix-editor/helix/wiki/Terminal-Support#enhanced-keyboard-protocol.