Prompt input does not handle emoji grapheme clusters

Discord username (optional)

paperdave.net

Describe the bug

warp's input buffer is unusable when using certain multi-codepoint emojis. i dont seem to reproduce this for all grapheme cluster types, just emojis.

To reproduce

• paste one of "🏳️‍⚧️", "❤️", "❤️‍🔥" into a block input
• look at what is echoed

Expected behavior

i would like to see one grapheme, similar to other terminals

but ideally, the cursor is actually sticks at the end of the single grapheme, since this is a GUI app with a gui text input; this prompt does not need to abide by wcrules.

support for proper grapheme cluster support is opened in #4190, which covers this more broadly.

Screenshots

(this is 🏳️‍⚧️)

Operating system

MacOS

Operating system and version

MacOS 13.6

Shell Version

fish, version 3.6.1

Current Warp version

v0.2024.02.13.08.02.stable_00

Regression

No, this bug or issue has existed throughout my experience using Warp

Recent working Warp date

No response

Additional context

This seems distinct from #1995 as this issue is looking at prompt and not the output. when used in a non-warpify shell, this emoji kind of renders differently

i think resolving this is covered by that issue or a new issue.

Does this block you from using Warp daily?

No

Is this a Warp specific issue? (i.e. does it happen in Terminal, iTerm, Kitty, etc.)

Yes, this I confirmed this only happens in Warp, not other terminals.

Warp Internal (ignore): linear-label:b9d78064-c89e-4973-b153-5178a31ee54e

None

Start by reviewing the broader grapheme-cluster work referenced in issue #4190 and reproduce the prompt behavior with 🏳️‍⚧️, ❤️, and ❤️‍🔥 on macOS. Done means each pasted emoji is echoed as one grapheme and the cursor remains at its end, matching the expected terminal behavior.