Module cells_render 

B2.4 (2026-06-04): DisplayMatrix → ratatui span conversion.

The TUI consumes the canonical lattice_host::display_matrix::DisplayMatrix published by the cells worker and emits a Vec<Span<'static>> ready for ratatui’s text widgets. This module is the substrate→TUI translation layer.

Why a separate module

A DisplayLine carries style-tagged byte runs (lattice_host::display_matrix::DisplayRun: a lattice_syntax::Style enum + non-style flag bits), NOT resolved colours — the renderer resolves style → fg + modifiers against the host theme at paint (truecolor Color::Rgb, or ratatui’s nearest-named downsample in low-colour terminals). display_line_to_source_spans walks the runs, drops INLAY runs so the spans cover source bytes one-to-one with the rope line (the overlay pipeline positions overlays by source-byte offset), groups consecutive runs with the same resolved style, and emits one [ratatui::text::Span] per group.

Pre-B2.4 this module converted the projected per-character cell grid (cell_row_to_source_spans); B2.4a cut the TUI over to the DisplayMatrix and B2.4b deleted the cell→span path. The remaining cell path (worker projection, GPU reader) goes away in B3/B4.

Functions

display_line_to_source_spans

B2.4 (2026-06-04): the DisplayLine analogue of [cell_row_to_source_spans] — the TUI’s source of document-body spans once it consumes the canonical DisplayMatrix directly instead of the projected cell grid. Walks line.runs, drops INLAY runs (so the spans cover source bytes one-to-one with the rope line — overlays positioned by source byte work unchanged), and resolves each run’s syntax style + flags → a ratatui [Style] via the host theme.