fix(storage-walker): honor <ol start> in storage → markdown

[pchuri]

Pull Request Template

Description

Storage → markdown now numbers ordered lists from <ol start> instead of always starting at 1.

<ol start="3"><li>three</li><li>four</li></ol>

now becomes 3. three\n4. four (it used to be 1. three\n2. four).

• Start validation: CommonMark ordered list markers are 1–9 digits. A start value that markdown cannot express falls back to 1. That covers negative, signed, non-integer and empty values, and runs whose last number would go past 999999999. Leading zeros and surrounding whitespace are ignored, and start="0" is kept. Empty <li> items still don't use up a number.
• Paragraph interruption: In CommonMark, only an ordered list that starts at 1 can interrupt a paragraph. Without a blank line, - Parent\n 3. Child is parsed as the single paragraph Parent 3. Child. A list with any other start is therefore separated by a blank line in three places:
  • after inline text (Steps:<ol start="3">…);
  • after a nested item's lead-in text;
  • after a callout header (> **INFO**\n>\n> 3. a). This uses a structural check that skips empty or comment nodes, looks through transparent wrappers (div, p, span, ac:layout*), and stops at leading prose, so a paragraph <p>3. a</p> or text like 3. fake is not affected.
• Where lists stay tight: after headings, thematic breaks and code fences, because those blocks can't absorb the next line.
• Marker width: since fix(storage-walker): preserve nested list structure in storage → markdown (#238) #239, the continuation indent comes from marker.length, so 9. → 10. indents nested content by 4 automatically.
• Markdown → storage: this already emits start, through markdown-it plus html-to-storage's attribute pass-through. Round trips md → storage → md → storage are now stable, and tests cover them.

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Performance improvement
• Code refactoring

Testing

• Tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes

npx jest: 39 suites and 1363 tests pass (after merging current main, including #247, #249 and #250). npx eslint lib tests is clean. The new tests in tests/macro-converter.test.js ("ordered list start (#241)") check exact output with toBe, including exact storage in the round-trip cases.

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• Any dependent changes have been merged and published in downstream modules

Additional Context

Follow-up to #238 / #239. The callout header separator is built on #249's quoteLines. These are known and left out of scope:

• Adjacent lists merge: <ol>…</ol><ol>…</ol> is read back as one markdown list, so the second list's start is lost. This already happens on main with plain <ol>s.
• reversed: markdown has no way to express this attribute.
• HTML → markdown path: lib/html-to-markdown.js, a separate converter, also ignores start. That is left for a follow-up.

Fixes #241

[github-actions]

🎉 This PR is included in version 2.25.6 🎉

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

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