Implemented CollectionReaderLayout for Essays Collection

Summary

Implemented a new documentation-style layout for the Essays collection with a sidebar navigation and main content area, using the AstroMarkdown component for rendering Markdown content.

Why Care

This layout provides a more intuitive reading experience for essay content with persistent navigation, making it easier for users to browse through multiple essays without returning to an index page. The implementation properly handles Markdown AST processing and rendering, ensuring consistent styling and behavior with other content types.

Implementation

Changes Made

Created new CollectionReaderLayout.astro in site/src/layouts/
Implemented Markdown processing pipeline using the unified library
Added proper styling for the two-column layout with responsive behavior
Modified EntryListItemPreview--Base.astro to use gradient borders for selected items
Connected the layout to the dynamic route in site/src/pages/read/through/[collection]/[...slug].astro

Technical Details

Markdown Processing Pipeline: Implemented the full unified processor chain with all necessary plugins:
javascript
```
// site/src/layouts/CollectionReaderLayout.astro
const processor = unified()
  .use(remarkParse)
  .use(remarkGfm)
  .use(remarkImages) 
  .use(remarkBacklinks)
  .use(remarkCitations)
  .use(remarkTableOfContents);
```

AST Node Structure: Properly filtered the MDAST node to separate Table of Contents from main content:

javascript

// site/src/layouts/CollectionReaderLayout.astro
node={{
  type: 'root',
  children: mdastNode.children ? mdastNode.children.filter(child => child.type !== 'tableOfContents') : [],
  data: mdastNode.data || {}
}}

Responsive Grid Layout: Implemented a flexible grid layout using Tailwind:

html

<!-- site/src/layouts/CollectionReaderLayout.astro -->
<div class="collection-reader-layout grid grid-cols-1 md:grid-cols-[1fr_2fr] lg:grid-cols-[1fr_3fr] gap-8">
  <aside><!-- Sidebar content --></aside>
  <main><!-- Main content --></main>
</div>

Active Item Styling: Enhanced the selected item in the sidebar with gradient borders:

css

/* site/src/components/articles/EntryListItemPreview--Base.astro */
.preview-base.active-preview-item::before,
.preview-base.active-preview-item::after {
  content: '';
  position: absolute;
  left: 0;
  right: 0;
  height: 2px;
  background: var(--grd--lossless-eastern-crimson);
}

Integration Points

The layout integrates with the existing AstroMarkdown.astro component for rendering Markdown content
Uses the ContentNavSidebar.astro component for navigation
Connects to the dynamic route system in site/src/pages/read/through/[collection]/[...slug].astro
Leverages existing styling variables and Tailwind classes for consistent appearance

Documentation

Added implementation insights to content/lost-in-public/prompts/user-interface/Create-a-New-Layout-for-Existing-Content-Collection.md documenting the critical requirements for properly integrating AstroMarkdown.astro into a layout component
Documented the specific node structure and props required for proper rendering
Included CSS patterns for styling the rendered content