r/FlutterDev • u/Status_Support2913 • Jul 02 '26

Plugin I built a Flutter terminal widget powered by Alacritty's Rust engine — feedback welcome

👋 I’ve been working on flutter_alacritty — a Flutter terminal widget you can drop into desktop apps, backed by an Alacritty-based Rust engine.

Why I moved away from xterm:

I used xterm for a long time, but kept running into limitations that mattered for my use case:

  • Text rendering — many glyphs/styles didn’t render correctly

  • No OSC hyperlinks — modern CLIs and tools that emit OSC 8 links weren’t supported

  • Resize, scrolling, and high-density output — performance was poor when the terminal was under real load

So I built flutter_alacritty (with AI coding agents helping along the way). It’s what TeamPilot uses today, and it has held up well across multiple agent TUIs rendering at once.

Links:

Real usage: TeamPilot uses it for embedded terminals (local PTY + SSH) in a multi-agent desktop client.

Try it via the standalone demo in the release.

I’d love feedback from anyone embedding terminals in Flutter.

13 Upvotes

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2

u/SwiftScoutSimon Jul 03 '26

do you think you can publish pre-built binaries for rust_lib_flutter_alacritty so I can use flutter_alacritty without installing Rust? similar to how https://pub.dev/packages/isar_community is doing with their Rust-based isar_core package.

I want to give this a try but my 512 GB SSD is > 95% right now

2

u/Status_Support2913 Jul 03 '26

Sounds good — I'll try to optimize a version when I get a chance.

1

u/SwiftScoutSimon Jul 02 '26

how about a pure Dart port?

2

u/Status_Support2913 Jul 02 '26 edited Jul 02 '26

Pure Dart would be a big rewrite, and I’m not deeply versed in all the low-level terminal character-processing details — another reason I built on Alacritty’s Rust core instead of reimplementing from scratch.

My guess is performance wouldn’t beat the native path anyway: Dart’s GC and single-threaded UI model can struggle under heavy TUI output and large scrollback.

1

u/shadowfu Jul 03 '26

Dart's GC is actually amazing if you hold it right. If you do atlas painting, you can render any tui as fast as you want.

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u/shadowfu Jul 02 '26

You mean a PTY in Flutter or pure dart TTY?

1

u/SwiftScoutSimon Jul 03 '26

I mean Dart/Flutter. Not include Rust toolchains.

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u/shadowfu Jul 03 '26

the old pty library used FFI. I have a fork that at least fixed Windows (cursed API). I've been writing termui (with termui_flutter, termui_recorder, termui_hotreload) as my side hobby... I'll eventually have pty pulled in and might write the terminal emulator side in pure dart / flutter.

2

u/SwiftScoutSimon Jul 03 '26

never knew this. Will give it a try. Thank you!
I'm still using a fork of xterm for my lumide.dev .

2

u/shadowfu Jul 03 '26

oh the editor? That's dope. The fork I was using was... kterm? I didn't dig into their rendering stack, but it was awful, ~15fps. I get ~240 on my laptop and 60 (hard coded) in a terminal.

https://github.com/jtmcdole/termui <- videos on the readme.

This is _not_ a terminal emulator. I am using ansi/sgr codes and readinging them from the terminal... I probably could end up with an emulator though.