Missing support for bracketed paste

[knz]

Bracketed paste is an optional feature that modifies how the terminal handles a "paste from clipboard" action by a user. (e.g. middle mouse click in xterm, ctrl+shift+v in vte, etc)

The feature must first be enabled by sending CSI ? 2004 h to the terminal. After bracketed paste is enabled, each pasted text gets enclosed between CSI 200~ and CSI 201~.

The reason why this feature exist is well explained in the wikipedia page:

Likewise, in the Bubbline library, which we intend to use for CockroachDB's SQL shell, we also want to interpret a manually entered newline as a special "run" command, but we also want to give users the option to paste a SQL text containing newline characters without running them.

Prototype implementation

These 3 PRs:

• [ ] termenv: https://github.com/muesli/termenv/pull/84
• [ ] bubbletea: https://github.com/charmbracelet/bubbletea/pull/397
• [ ] bubbles: https://github.com/charmbracelet/bubbles/pull/214

Terminal support

Terminal	Bracketed Paste
alacritty	✅
foot	✅
kitty	✅
Konsole	✅
rxvt	✅
screen	❌ [^screen]
st	✅
tmux	✅
vte-based	✅
wezterm	✅
xterm	✅
Linux Console	❌
Apple Terminal	✅
iTerm	✅
Windows cmd	❌
Windows Terminal	✅

[^screen]: A patch is available here https://gist.github.com/saitoha/2977889

[knz]

See public slack discussion here: https://charmbracelet.slack.com/archives/CQ2E9CGTV/p1660812723955889

[knz]

There's a couple implementation questions here:

1. do we try to enable BP always in termenv?

   • this seems safe and unlikely to confuse terminals. If a terminal does not support BP, it will ignore the CSI code.
   • however, once we do this we must also ensure that all the bubble widgets know how to handle text pasted this way.

2. how to represent bracketed pastes in bubbletea?

   • the proposed implementation re-uses the existing KeyRunes message type.
     • Pro: this makes it possible to immediately support any widget code that handle rune sequences.
     • Con: we need to patch a few widgets to handle newlines inside KeyRunes properly
   • we could introduce a new, separate message type.
     • Pro: no surprise in widgets unless someone explicitly supports the new message type
     • Con 1: pasting text from clipboard will appear to "do nothing" until the developer actually does the work. This might confuse users.
     • Con 2: it will likely cause redundant logic with the handling of KeyRunes in input handlers (since both will usually need the same behavior)

[knz]

Two real-world consequences:

• https://github.com/cockroachdb/cockroach/issues/93135
• https://github.com/cockroachdb/cockroach/issues/93346

[knz]

More: https://github.com/cockroachdb/cockroach/issues/94341