HTML Report Missing Detail Data - Only Summary Counts Displayed

[jbrinkman]

Problem Description

The HTML report generated by the Scriban formatter is displaying correct summary counts but missing detail data in the main content sections.

Observed Behavior

✅ Working correctly:

• Configuration section displays properly with collapsible details
• Summary cards show correct counts (139 Added, 132 Removed, 132 Breaking)
• Overall layout and styling render correctly

❌ Not working:

• Breaking Changes section shows count but no individual change details
• Added Items section shows count but no individual items listed
• Removed Items section shows count but no individual items listed
• Modified Items section (if any) would likely have the same issue

Expected Behavior

Each section should display:

• Individual change items grouped by type (Class, Method, Property, etc.)
• Element names and descriptions for each change
• Signature differences where applicable (old vs new)
• Breaking change indicators and severity levels

Technical Analysis

The issue appears to be in the data preparation or template rendering logic in HtmlFormatterScriban.cs:

1. Data Preparation: Methods like PrepareChangeSections() and GroupChanges() may not be properly formatting the data structure expected by the Scriban templates
2. Template Rendering: The Scriban templates (particularly change-group.scriban and breaking-changes.scriban) may not be receiving the correct data structure or may have syntax issues
3. Template Include Logic: The {{ include }} directives may not be working correctly with the CustomTemplateLoader

Impact

• Severity: High - The primary purpose of the HTML formatter is to display detailed change information
• User Experience: Users see summary counts but cannot access the actual details of what changed
• Functionality: Core feature is broken despite showing no errors during report generation

Files Likely Involved

• src/DotNetApiDiff/Reporting/HtmlFormatterScriban.cs - Data preparation methods
• src/DotNetApiDiff/Reporting/HtmlTemplates/change-group.scriban - Change item display template
• src/DotNetApiDiff/Reporting/HtmlTemplates/breaking-changes.scriban - Breaking changes template
• src/DotNetApiDiff/Reporting/HtmlTemplates/main-layout.scriban - Main template with include directives
• src/DotNetApiDiff/Reporting/CustomTemplateLoader.cs - Template include functionality

Steps to Reproduce

1. Run API comparison between two assemblies with differences
2. Generate HTML report: --output html --output-file report.html
3. Open generated HTML file
4. Observe that summary shows counts but detail sections are empty

Acceptance Criteria

• Breaking Changes section displays individual breaking changes with severity and descriptions
• Added Items section shows all newly added API members grouped by type
• Removed Items section shows all removed API members grouped by type
• Modified Items section shows changed API members with before/after details
• All sections properly expand/collapse and maintain responsive design
• Template include functionality works correctly for all partial templates