The "Thinking" (reasoning) block rendered with large vertical gaps: models
emit reasoning with a blank line (\n\n) between every list item and
paragraph, which `marked` turns into loose lists (each <li> wrapped in a
<p>) and separate <p> paragraphs, each carrying a margin.
- Add `collapseBlankLines(text)`: collapse 2+ newlines to one, EXCEPT inside
fenced code blocks (``` / ~~~) where blank lines are significant. Applied
in reasoning-block.tsx before renderChatMarkdown, so loose lists become
tight (no <li><p>) and paragraphs join; `breaks: true` keeps single \n as
<br>, preserving line breaks. Reasoning-only — the normal answer is
untouched.
- Drop `white-space: pre-wrap` from `.reasoningText`: on the rendered
markdown <div> it turned the newlines between block tags into visible
blank lines on top of the margins. The plain-text fallback <Text> that
needs pre-wrap already sets it inline.
Tests: collapseBlankLines unit (collapse, fence preservation incl. tilde and
unclosed fences) + rendered-HTML assertions that a blank-line-separated list
becomes a tight list and still parses as a list after a paragraph.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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