Allow multi-key keybinds

[pjz]

Currently all keybinds must be one single 'chord'.

I'd like support for a key sequence - that is, multiple keys pressed in a row.

This would allow me to emulate tmux/screen's keybindings

[gegoune]

That sounds similar to Wezterm's key_tables.

[pjz]

Point of reference: Kitty uses > to denote a sequence. Eg. ctrl+b>c is ctrl-b followed by the letter c.

[mitchellh]

I approve of the > syntax for sequences.

[pjz]

As discussed on discord, we don't have to have a timeout for the leader keys, which makes this significantly easier.

While @mitchellh has experience that vim does a timeout, none of tmux, screen, or kitty do - they seem to wait forever once the leader is pressed to see if it completes a keybind.

A keybind can be built to emit the leader, like: ctrl+a>a=ctrl+a or if that's confusing perhaps ctrl+a>a=text:\x01

A max sequence length (perhaps four, to keep emacs people happy?) should be put into a const in input/Binding.zig and use it in Surface.zig. The binding trigger parse code needn't use a statically allocated array but it can check if someone tries to do more than the max and error.

[bentay]

This issue is the only reason I still use tmux inside of Ghostty on my daily driver. Would love to have it! :)

[mitchellh]

From Discord, more details:

• If you define a bunch of sequences like ctrl+a>... and then do keybind = ctrl+a=scroll_up, all previous sequences are deleted.
• If you define a sequence ctrl+a>b and then type ctrl+a>c, then the encoded input for all leaders up to the final are sent to the pty.
• We should have some visual indication we're in the middle of sequence. A proposal was a URL-style overlay showing the currently pending sequence.

[mitchellh]

I've started working on this, and I've realized one downside of the already approved > syntax is that it requires quoting on the command line, which is potentially unfortunate. ☹️ First person to recommend a unicode arrow like → is uninvited from the beta. 🤣

For now I'm going to carry on with > because its very very easy to change this later (before merge at least), but I wanted to post this comment in case anyone had any other thoughts.

[nfejzic]

one downside of the already approved > syntax is that it requires quoting on the command line

Would a comma work well? Something like ctrl+a,b. Comma would nicely indicate a (short) pause between different key combos.

[mitchellh]

PR is up #2121.

The sequenced keybind PR somewhat dramatically overhauls how we do binding handling so even if you don't use sequences, I'd love if some folks who are comfortable building from source can bash on that PR a bit and see if they see anything wonky.