Check Code Block Highlights

Verify that hl_lines attributes in markdown code blocks are correctly set to highlight the intended lines.

See ../shared/repo-conventions.md for file conventions.

Critical Understanding

hl_lines is snippet-relative, NOT related to linenums:

• linenums="21" sets the displayed starting line number
• hl_lines="3" highlights the 3rd line of the snippet (which displays as line 23)
• These are completely independent attributes

Example: