letui

demo.mp4

TUI library written using Rust and TypeScript

Since v0.0.11

• Added socket-based test driver for automated checks (ping, sleep, key, mouse, focused, snapshot, quit)
• Stopped sending full text payload on every paint() call
• Added Rust-side text registry keyed by node id + per-frame text diff sync
• Batched text upsert/delete operations into single sync_text_ops FFI call per frame
• Improved terminal flush batching to track terminal cells (not UTF-8 byte length) for cleaner multibyte rendering
• Added stronger quit cleanup path (stop test driver, clear text registry, free buffers, deinit terminal)

Core dependencies:

• crossterm - cross-platform terminal manipulation library
• taffy - UI layout engine

TODO:

• Scrollable containers: route wheel/touchpad events (deltaX/deltaY) to nearest scrollable container
• Scrollable containers: add overflow: "hidden" prop to trigger clipping during paint
• Scrollable containers: add scrollX/scrollY signals per scrollable node
• Scrollable containers: pass scissor rect to Rust paint to skip out-of-bounds cells
• Scrollable containers: implement horizontal scrolling first, then vertical
• Styled text chunks: add TextChunk type { text: string; fg?: number; bg?: number; bold?: boolean }
• Styled text chunks: update Text to accept TextChunk[] or plain string
• Styled text chunks: serialize chunks to Rust renderer
• Text input: improve single-line input (cursor position, selection)
• Text input: add multi-line editor (builds on scrollable + input)
• Syntax highlighting: integrate Tree-sitter (Rust bindings -> FFI)
• Syntax highlighting: load TextMate-compatible themes (like OpenTUI SyntaxStyle)
• Performance: define wall-of-text serialization strategy (thread)
• Performance: add render caching to skip serialize/layout when signals unchanged (pi-mono pattern)
• Performance: implement incremental tree updates instead of rebuilding Taffy tree each frame
• Performance: add visibility culling to skip paint() for off-screen nodes (OpenTUI _getVisibleChildren)
• Experiment: explore Neovim as text input (use Bun PTY support)
• Experiment: evaluate SIMD for tree diff / serialization comparisons
• Performance: refactor flush with BatchWriter pattern
• Tooling: add performance stats overlay that updates independently from app render

NPM publish notes:

1. push your changes
2. update versions in Cargo.toml and package.json
3. git tag v0.0.1 - tag a commit
4. git push origin v0.0.1 - push the tag
5. release action will build and deploy it as package

Benchmark Results (letui vs Rezi) - may not be accurate, just playing around right now

Latest run: 2026-02-20 (terminal-rerender, full profile, PTY mode)

Run config:

• warmup=100
• iterations=1000
• replicates=7 (first replicate discarded)
• command: bun run bench/run.ts --profile full --scenario terminal-rerender

Metric	letui	Rezi	Delta
Mean latency	20 us	259 us	letui 12.69x faster
p95 latency	21 us	260 us	letui lower
Throughput	48.6K ops/s	3.9K ops/s	letui 12.46x higher
Peak RSS	60.4 MB	128.2 MB	letui 2.12x lower
PTY bytes	43.2 KB	30.1 KB	letui 1.43x higher