Bug 515330

Summary:	Markdown code blocks are not syntax highlighted in rendered preview
Product:	[Frameworks and Libraries] markdownpart	Reporter:	Ricardo <zanetti>
Component:	general	Assignee:	Friedrich W. H. Kossebau <kossebau>
Status:	REPORTED ---
Severity:	normal	Keywords:	qt6, usability
Priority:	NOR
Version First Reported In:	unspecified
Target Milestone:	---
Platform:	Arch Linux
OS:	Linux
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:

Description Ricardo 2026-01-31 07:48:44 UTC

SUMMARY
Markdown code blocks are not syntax highlighted in rendered preview

STEPS TO REPRODUCE
1. Open any Markdown file containing fenced code blocks with language specifiers (e.g., ```bash, ```python, ```javascript)
2. View the rendered Markdown preview using markdownpart (in Kate, Ghostwriter, KleverNotes, ReText, or any KParts-based application)
3. Observe the code blocks in the preview

OBSERVED RESULT
Code blocks appear in monospace font but without any syntax highlighting. All code text is displayed in the same color regardless of the specified language.

EXPECTED RESULT
Code blocks should be syntax highlighted according to the language specified in the fence (```bash, ```python, etc.), using KSyntaxHighlighting framework or similar to apply appropriate colors to keywords, strings, comments, and other language elements.

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Arch Linux (kernel 6.12.10)
KDE Plasma Version: 6.5.5
KDE Frameworks Version: 6.11.0
Qt Version: 6.8.1
markdownpart Version: 25.12.1-1

ADDITIONAL INFORMATION
Investigation shows that markdownpart uses libmd4c for Markdown parsing but does not link against KSyntaxHighlighting or any other syntax highlighting library (verified with ldd). The generated HTML contains plain <code> tags without highlighting classes or inline styles.

KDE already has the necessary infrastructure for syntax highlighting (KSyntaxHighlighting framework with definitions in /usr/share/org.kde.syntax-highlighting/syntax-bundled/), which is used successfully in Kate's editor view. Integrating this into markdownpart would provide consistent, high-quality syntax highlighting for code blocks in Markdown previews across all KParts-based applications.

This affects user experience when viewing technical documentation, code snippets, or any Markdown content with code examples in Kate, Ghostwriter, KleverNotes, ReText, and other KDE applications that use markdownpart.

Related resources:
- KSyntaxHighlighting framework: https://api.kde.org/frameworks/syntax-highlighting/html/
- CommonMark spec on fenced code blocks: https://spec.commonmark.org/0.31.2/#fenced-code-blocks