Feature: Support @mentions and HTML formatting

[steveclarke]

Summary

Port the {{@Username}} mention syntax and HTML formatting support from the MCP server to the Ruby CLI.

Background

The TypeScript MCP server (mcp-superthread-plus) already implements this feature. SuperThread comments and checklist items support:

1. HTML formatting - <strong>, <em>, <code>, <ul>, <blockquote>, etc.
2. @mentions - Using {{@Username}} syntax that converts to <user-mention> HTML tags

Applies To

• Comments (content)
• Replies (content)
• Checklist item titles

Implementation

The MCP server has a formatMentions() utility in src/utils.ts that:

1. Looks up workspace members by name
2. Converts {{@Username}} to <user-mention data-type="mention" user-id="..." ...>
3. Supports escaping with \{{@Name}} for literal output

References

• MCP server implementation: mcp-superthread-plus/src/utils.ts (lines 135-239)
• Item 16 in notes/manual-integration-testing.md

[steveclarke]

Note: HTML-to-text utility needed

While working on checklist display (#18 fixes), discovered that checklist item titles can contain HTML (e.g., <p>Foo</p>). Currently using Nokogiri inline to strip tags:

title = Nokogiri::HTML.fragment(item.title).text.strip

Recommendation: Create a standardized HtmlUtils module or similar with:

• strip_tags(html) - Convert HTML to plain text (for CLI display)
• format_mentions(text, members) - Convert {{@Username}} to HTML mentions

This would centralize HTML handling and ensure consistent behavior across:

• Checklist item titles
• Comment content
• Card content previews
• Any other API responses containing HTML

Related: The truncate_content method in lib/superthread/cli/base.rb:515 also does basic HTML stripping with regex - should be updated to use the shared utility.