scrollback — scrollback snapshot writer

Types for capturing a solid component tree into a scrollback snapshot — the rendered output preserved above the visible terminal area. Port status: scaffolded. The types and signatures are in place, but the writer produces an empty snapshot and the main entry point is a no-op.

Types

pub struct SolidScrollbackWriterOptions {
    pub width: Option<u16>,
    pub height: Option<u16>,
    pub row_columns: Option<u16>,
    pub start_on_new_line: Option<bool>,
    pub trailing_newline: Option<bool>,
}
// Default: start_on_new_line = Some(true), everything else None.

pub struct ScrollbackSnapshot {
    pub root: RootRenderable,
    pub width: u16,
    pub height: u16,
    pub row_columns: Option<u16>,
    pub start_on_new_line: bool,
    pub trailing_newline: bool,
}

pub struct ScrollbackRenderContext {
    pub width: u16,
    pub tail_column: u16,     // where the current line tail starts
}

pub type ScrollbackWriter = Box<dyn Fn(ScrollbackRenderContext) -> ScrollbackSnapshot>;

Functions

pub fn create_scrollback_writer(
    _node: Box<dyn Fn(&ScrollbackRenderContext)>,
    _options: SolidScrollbackWriterOptions,
) -> ScrollbackWriter

pub fn write_solid_to_scrollback(
    _renderer: (),
    _node: Box<dyn Fn(&ScrollbackRenderContext)>,
    _options: SolidScrollbackWriterOptions,
)

• create_scrollback_writer currently returns a writer that always produces an empty snapshot: root: RootRenderable::new(), height: 1, trailing_newline: false, sized from the context’s width.
• write_solid_to_scrollback is a no-op stub.

The design intent (per the source comments): integrate with the ratatui backend and the LayoutTree once the renderer exposes a scrollback surface API equivalent to the original OptimizedBuffer path — i.e. render the component tree into an off-screen buffer and hand it to the terminal’s scrollback.

Practical guidance

Scrollback capture is not yet functional; treat these as forward-compatible API scaffolding. To render content off-screen today, render widgets into an in-memory ratatui::buffer::Buffer yourself (the same approach the core example uses).

Next: time_to_first_draw — TTFD marker.