ratatui

# Ratatui Write current, compiling Ratatui code (pinned to **0.30.x**, Rust 2024) and refuse the stale tui-rs patterns the model remembers from training. The body is the load-bearing 20%: one mental model and one verified example per concept. Everything enumerable — the full widget catalog, every constraint, the streaming model, testing, migration — lives in `references/`. Open the matching reference before writing nontrivial code in that area. ## Mental model Ratatui is **immediate mode**: there are no retained widget objects. Every frame you build the whole UI from your own application state and throw it away. A render loop runs `terminal.draw(|frame| …)`; inside, you slice the area into rectangles and draw widgets into them. Ratatui keeps two `Buffer`s and **diffs** them, writing only the changed cells to the terminal — so redrawing the entire screen every frame is cheap and correct. You own the loop: read an event, update state, draw, repeat. Four nouns carry everything: - **Terminal** — owns the backend (crossterm by default) and the double buffers; gives you a `Frame`. - **Frame** — one frame's drawing surface; `frame.area()` is the full `Rect`, `frame.render_widget(w, rect)` draws. - **Buffer** — the grid of styled cells widgets write into. Dimensions are `u16` (max 65,535 per side). - **Rect** — an `x/y/width/height` region in `u16`. Layout is just splitting one `Rect` into more `Rect`s. ## Lifecycle: never hand-roll the terminal Ratatui sets up raw mode, the a...