Comparison with other TUI frameworks

Verum's TUI stack is a late-comer to an industry with mature options. It borrows freely from all of them, and differs in a few opinionated ways.

At a glance

Aspect	Verum core.term	Ratatui (Rust)	Textual (Python)	Ink (Node)	Bubble Tea (Go)
Architecture	TEA — Elm	Immediate	Reactive / CSS	React + hooks	TEA — Elm
Rendering	Double-buffer + diff + row-skip + sync-output	Double-buffer + diff	Diff + dirty regions	VDOM diff	Double-buffer + diff
Layout	Constraint + Flex + Grid	Constraint only	CSS Grid / Flex	Yoga flex	Lip Gloss manual
Widgets	20 built-in	~20	~40	~15 via Ink UI	Bubbles set (~15)
Async	Command.task(future) native	tokio you wire yourself	async def, native	async/await	tea.Cmd = func() Msg
Subscriptions	First-class Subscription	Manual	CSS watchers, reactive	useEffect	tea.Sub (deprecated — now Cmd)
Cancellation	Structured, automatic	Manual	Automatic	Manual	Manual
Unicode	Grapheme-aware; ZWJ emoji, flags	Via unicode-width	Full	Full	runewidth
Mouse	SGR 1006	SGR 1006	SGR 1006	SGR 1006	SGR 1006
Graphics	Kitty + Sixel + iTerm2 + Braille fallback	Via third-party	Limited	No	No
Clipboard	OSC 52 built-in	Via third-party	Via pyperclip	clipboardy	clipboard-go
Accessibility	OSC 133 zones	No	Partial	No	No
Colour profile	Auto-detect + CIELAB downsampling	Auto-detect (naive)	CSS variables	Truecolor only	Auto-detect
Testing	Pure update, snapshot Buffer	Mock terminal	pytest snapshots	ink-testing-library	Model testing

What Verum does better

• Out-of-box graphics. Kitty + Sixel + iTerm + Braille fallback is one function call (create_graphics_renderer(caps, writer)).
• Structured async. Command.task(future) is spawned on the same runtime that backs core.async; cancellation is wired automatically.
• Perceptual colour adaptation. CIELAB distance gives the right fallback on 16-colour shells; naive RGB distance (Ratatui, Bubble Tea) does not.
• Full Flex + Grid. Ratatui ships only Constraint; Verum has CSS Flex Level 1 plus CSS Grid Level 1 with fr units and minmax().
• Strong typing end-to-end. Verum's Command<Msg> is parameterised; Bubble Tea's is func() tea.Msg with interface{} payloads.

What Textual does better (today)

• Declarative CSS. Textual's TCSS is the most ergonomic terminal styling language. Verum's Theme + Style builder is equivalent in expressive power but not in terseness for static skins. This is on the roadmap — see the theming guide.
• 40+ widgets. Textual's widget library is the biggest in the industry. Verum ships 20 production-grade widgets; most missing ones (DataTable, Switch, TabbedContent, Markdown, DirectoryTree) can be assembled from existing primitives in < 200 lines.
• Web deployment. Textual apps can run in a browser via textual serve. Verum's path here goes through WASM + xterm.js; not yet shipped.

What Ink/React-style does better

• Component reuse. React hooks make per-widget state trivial to share between components. Verum's StatefulWidget with an associated State type is equivalent but more boilerplate.

Migration notes

• From Ratatui. The rendering layer (Buffer, Frame, Widget) is almost 1:1 — Cell, set_string, set_style, get_mut — so porting widgets is mostly a syntax exercise. The app layer is different (TEA vs immediate); but if your Ratatui app used tokio + a state machine you're halfway to TEA already.
• From Bubble Tea. The Elm architecture maps straight across. tea.Cmd ↔ Command; tea.Sub ↔ Subscription; tea.Model.Update ↔ Model.update; tea.Model.View ↔ Model.view. The biggest difference: Verum commands are typed by Msg, not interface{}.
• From Textual. Reactive attributes become explicit Msg transitions in update. CSS rules become Theme + Style at render time. Timer watchers become Subscription.interval.