feat: add syntax highlighting to code blocks - #84
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Highlight fenced code blocks server-side with syntect. Class-based output keeps a single pre-rendered copy of the HTML valid for all five themes; token colors are CSS vars redefined per data-theme, so theme switching stays client-side and instant. The markdown crate exposes no hook for code block output, so blocks are rewritten in the generated HTML. Mermaid blocks are skipped because the client-side renderer reads their textContent verbatim. Syntax set comes from two-face instead of syntect's defaults, which lack TypeScript, TOML, and Dockerfile. Costs 2.2MB of binary size and a one-time ~200ms SyntaxSet load on the first file containing a code block.
This was referenced Jul 27, 2026
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Closes #24.
Fenced code blocks are highlighted server-side with syntect. Output is class-based, so one pre-rendered copy of the HTML serves all five themes and theme switching stays client-side.
Approach
hl--prefixed scope classes instead of inline styles. Token colors are CSS vars (--hl-keyword,--hl-string, ...) redefined perdata-theme- GitHub light/dark palettes for those two themes, Catppuccin palettes for the other three.highlight_code_blocksrewrites<pre><code class="language-*">in the generated HTML.shell,golang,c++,yml,kt).Cost
regex-fancy, no oniguruma), so no C toolchain - the single-binary holds.Tests
44 pass, clippy
-D warningsclean, fmt clean. 7 new tests cover entitydecode/re-encode, alias resolution, scope classes, and the three skip cases.