Paragraph "between" borders (w:pBdr/w:between)

[caio-pizzol]

Summary

Render w:between paragraph borders — the horizontal line drawn between consecutive paragraphs that share the same border group.

Current State

Basic paragraph borders (w:pBdr) for the 4 standard sides (top, bottom, left, right) are already implemented:

• Converter: pBdr-translator.js parses all 6 sides (including between and bar) and stores them in paragraphProperties.borders
• Style-engine: borders flow through the full cascade (docDefaults → styles → inline)
• pm-adapter: normalizeParagraphBorders() converts top, right, bottom, left to layout format
• DomPainter: renders borders as an absolutely-positioned overlay div with CSS border properties

However, between borders are parsed but silently dropped in normalizeParagraphBorders() — only ['top', 'right', 'bottom', 'left'] are processed. The between value never reaches the DomPainter.

Problem

When a Word document uses w:pBdr/w:between to draw horizontal separators between consecutive paragraphs in a border group (e.g., callout boxes, grouped list items), the separator lines don't render in SuperDoc.

What needs to change

1. pm-adapter (packages/layout-engine/pm-adapter/src/attributes/borders.ts): Include between in normalizeParagraphBorders() so it flows to the layout format.
2. Contracts (packages/layout-engine/contracts/src/index.ts): Add between to the ParagraphBorder type on ParagraphAttrs.
3. DomPainter (packages/layout-engine/painters/dom/src/renderer.ts): Render between borders. This is the trickiest part — between borders are drawn as a horizontal line at the bottom of each paragraph in the group except the last one. The renderer needs to know whether the next paragraph shares the same border group.

Notes

• OOXML spec §17.3.1.24 defines w:between behavior
• The bar border (vertical decorative bar) is a separate feature tracked in a different issue
• The existing test documents attached to this issue can be used for validation

Attachments

paragraph_borders_all_styles_0.5pt_TOP_ONLY.docx

paragraph_borders_2pt_single_colors.docx

paragraph_borders_all_styles_0.5pt.docx

paragraph_borders_all_styles_2pt.docx

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Ref: SD-1741

[linear]

IT-529

[gpardhivvarma]

can take this up