Add --tags CLI option for atomic tag wrapping mode

[jlevy]

Summary

• Add --tags CLI option to control how template tags (Markdoc/Jinja/HTML comments) are handled during line wrapping
• atomic (default): Tags are never broken across lines
• wrap: Tags can wrap like normal text (legacy behavior)

Key Changes

• Add TagWrapping enum with atomic and wrap values
• Add --tags CLI argument to flowmark command
• Thread tags parameter through fill_markdown() and related functions
• Apply multiline tag fix in both modes (Markdoc parser bug workaround from Line wrapping inside Markdoc tags breaks parser when closing tag is on same line #17)
• Update test_multiline_tag_through_pipeline for correct expectations

Implementation Notes

The implementation uses coalescing-based word splitting for both modes, allowing long tags to wrap at internal whitespace boundaries while keeping tag contents together where possible. Closing tags are placed on their own line when the opening tag spans multiple lines.

Specs:

• Plan Spec
• Validation Spec

Test Plan

Automated Testing (Completed)

• 160 tests pass (make test)
• Lint passes with 0 errors, 0 warnings (make lint)
• 26 tag formatting tests in test_tag_formatting.py cover:
  • Quote preservation in tag attributes
  • Multi-line tag handling
  • Paired tag adjacency
  • Closing tag placement
  • Various tag types (Jinja, HTML comments, etc.)
• Reference doc tests verify full formatting pipeline against comprehensive test document

Manual Validation

1. CLI Option Verification

   • Check flowmark --help | grep -A2 tags shows new option
   • Test atomic mode (default) with a long tag
   • Test wrap mode explicitly with --tags=wrap

2. Verify Testdoc Output

   • Spot-check tag formatting around line 1700 in testdoc output
   • Long tags should wrap at internal whitespace
   • Closing tags should be on their own line

3. Backward Compatibility - Format existing Markdown files with Markdoc tags and verify they format correctly

🤖 Generated with Claude Code

[jlevy]

Addresses #13