Summary

• Fix incorrect multi-level list numbering when items continue a flat sequence at different indentation levels
• Documents with items like 1., 2., 3. at level 0 followed by item at level 1 (with start=4) now render as "4." instead of "3.4"
• Fix inconsistent indentation across list items at the same level
• Add documentation for OOXML corner cases

The Problem

In the NVCA-Model-COI document, a numbered list had:

• Items 1-3 at ilvl=0 with format %1. → displayed correctly as "1.", "2.", "3."
• Item 4 at ilvl=1 with format %1.%2 and start=4 → was displaying as "3.4" instead of "4."

Microsoft Word shows "4." because it detects this as a "continuation pattern" - a flat list that happens to use different indentation levels.

Additionally, items 2-4 had different indentation than item 1 (0.5in vs 0.25in wrapper width) due to a mutation bug.

The Fix

1. Continuation Pattern Detection

Added "continuation pattern" detection in ListItemRetriever.cs:

1. Detection: A paragraph at ilvl > 0 is in a continuation pattern when:

   • It's the first paragraph at this level AND
   • The level's start value equals the parent level's counter + 1
   • OR it inherits continuation status from a previous paragraph at the same level

2. Handling: When detected, uses level 0's format string with the current level's counter value

2. Numbering Definition Mutation Fix

Fixed mutation bug in FormattingAssembler.cs:

• The code was modifying the original numbering definition's pPr element by calling .Remove() on its child elements
• This caused subsequent list items using the same numbering level to lose their tab definitions
• Fixed by cloning numberingParaProps before modifying

3. Tab Width Calculation Fix

Updated WmlToHtmlConverter.cs to check accumulated properties (pt:pPr) first for indentation and tabs, falling back to direct properties (w:pPr) if not found.

Changes

• Docxodus/ListItemRetriever.cs - Added ContinuationInfo class and detection/handling logic
• Docxodus/FormattingAssembler.cs - Clone numberingParaProps before mutation; use effective level for properties
• Docxodus/WmlToHtmlConverter.cs - Check pt:pPr first for tabs and indentation
• docs/ooxml_corner_cases.md - New documentation for OOXML edge cases
• CLAUDE.md - Added section on documenting corner cases
• CHANGELOG.md - Added entry for this fix

Test plan

• Build succeeds with no warnings
• All 1178 tests pass
• NVCA document now renders item 4 as "4." instead of "3.4"
• All 4 list items have consistent 0.25in wrapper width