markdown: reflow soft line breaks instead of rendering them as hard breaks - #2947
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mdast hands the line ending over exactly as the source wrote it, so a CRLF document keeps its carriage return inside the `Node::Text` value. Replacing only the newline left the CR stranded in the middle of the reflowed line, where it reaches the text run — visible to copy, to measurement, and to whatever the shaper makes of a bare control character. Before this arm existed the CR sat against the line break and stayed out of the way, so the reflow is what exposed it. Take the CR with the newline, and cover the arm: - `test_soft_break_reflows_to_space` over LF, CRLF and a lone CR. - `test_soft_break_reflows_while_hard_break_survives`, which pins the invariant the collapse rests on — a hard break arrives as `Node::Break` and never as a newline inside `Node::Text`. Also drop the claim that the swap has to be length-preserving for inline mark offsets. `parse_paragraph`'s return value is discarded at every call site; the offsets are recomputed from `merged_text.len()` in `merge_children_with_mark`. Nothing downstream depends on the length, and saying otherwise would rule out this fix, which turns two bytes into one. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01AEg8SEHNEgRDcZ9mDj1p6r
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enabled auto-merge (squash)
September 4, 2026 11:30
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A CommonMark soft break lives inside a
Node::Textvalue as a plain\n. Therenderer treats any
\nin a text run as a line break, so a paragraph that ishard-wrapped in the source renders one visual line per source line instead of
reflowing to the available width.
Reproduction
Renders as two lines even with 1 200 px of free width. Expected one wrapped
line.
Measured on a 3 874-note vault: 10.9 % of notes (421) contain hard-wrapped
prose and rendered wrong.
Fix
Collapse
\nto a space in theNode::Textarm. Hard breaks are unaffected:they arrive as their own
Node::Breakand never reach this arm. The swap islength-preserving, so inline mark offsets computed against the text stay valid.
crates/base/src/text/format/markdown.rs, +11 −2. Best reviewed after thehard-break PR, which adds the
Node::Breakarm this one relies on for thedistinction.