Soft breaks in PR descriptions render as hard line breaks on desktop but not mobile

[ashleymcnamara]

Description

PR descriptions written with hard-wrapped lines (~80 columns) render differently on desktop vs. mobile. Single newlines inside paragraphs — which are soft breaks per CommonMark/GFM spec — are rendered as visible line breaks on desktop, but correctly collapsed to spaces on mobile.

Reproduction

1. Open feat(storage): add S3 Object Annotations backend (named annotations, base64-chunked items, AWS ships the SELECT) ExtendDB/extenddb#174 on desktop (Chrome, macOS)
2. Note the mid-sentence line breaks in the PR description body (e.g., "PR Sourcepos fixes #54 added a" breaks before "Route 53 storage backend...")
3. Open the same URL on mobile (iOS Safari) — the text flows as expected

The markdown source uses standard hard-wrapping at ~80 columns with no trailing spaces or backslashes. There are no intentional hard breaks. The source is valid CommonMark.

Desktop rendering (screenshot)

Expected behavior

Soft breaks should render consistently across desktop and mobile. Per CommonMark spec, a single newline in a paragraph should be treated as a space (or at minimum, both renderers should agree on how to handle it).

Actual behavior

Desktop renders soft breaks as <br> (hard line breaks). Mobile renders them as spaces. Same content, same context (PR description body), different output.

Related issues

• Update documentation to state GitHub's soft break parsing behavoir #344 (documenting the soft/hard break divergence between contexts)
• Is automatic line breaks a feature of GFM? #198 (asking whether auto line breaks in comments are per-spec)