@termless/alacritty

Alacritty backend for Termless -- headless terminal emulation using the alacritty_terminal Rust crate via napi-rs.

Status

Work in progress. The TypeScript wrapper and Rust native module source are complete, but the native binary needs to be compiled before the backend is functional.

Architecture

TypeScript (backend.ts)
  └── napi-rs bridge (native/src/lib.rs)
        └── alacritty_terminal 0.25 (Rust crate)
              └── vte 0.15 (VT parser)

The native module exposes AlacrittyTerminal as a napi class with methods for feeding data, reading cells/cursor/modes, resizing, and scrollback. The TypeScript layer wraps this to implement the TerminalBackend interface.

Characteristics

Compared to the xterm.js and Ghostty backends:

| Feature | alacritty | xterm.js | ghostty | | ---------------- | -------------------- | ----------- | ----------- | | Truecolor | Yes | Yes | Yes | | Kitty keyboard | Yes | No | Yes | | Kitty graphics | No | No | No | | Sixel | No | No | No | | Underline styles | All 5 | Single only | Single only | | Reflow | Yes | Yes | Yes | | Cursor styles | Block/Underline/Beam | Block only | Block only |

Building

Prerequisites

• Rust toolchain: curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh
• napi-rs CLI: bun add -g @napi-rs/cli

Compile

cd packages/alacritty/native
cargo build --release

# The output will be at:
#   target/release/libtermless_alacritty_native.dylib  (macOS)
#   target/release/libtermless_alacritty_native.so     (Linux)

# TODO: Use napi-rs CLI for proper .node binary generation:
# npx napi build --release

Test

bun vitest run packages/alacritty/tests/

Usage

import { createAlacrittyBackend } from "@termless/alacritty"

const backend = createAlacrittyBackend()
backend.init({ cols: 80, rows: 24 })
backend.feed(new TextEncoder().encode("Hello, Alacritty!"))
console.log(backend.getText()) // "Hello, Alacritty!"
backend.destroy()

TODO

• [ ] Set up napi-rs build pipeline (generates platform-specific .node binaries)
• [ ] Add to cross-backend.test.ts once native module builds
• [ ] CI: build native binaries for all target platforms
• [ ] Publish as npm package with prebuilt binaries