- Merge: defensive copy `new List<ElementInfo>(derived.Children)` so a
later mutation of the merged result or the input can't corrupt the other
- Merge: add comment on Width/Height 0-sentinel (Plan-1 safe; Plan-2
limitation and float?-upgrade path documented inline)
- Test: replace mid-sentence "Wait —" authoring trace in
EdgeFlagsToAnchors_ValueThree_FallsBackToTopLeft with a clean
conclusion-first summary of the value-3 mapping rule
9/9 ElementReaderTests pass; 0 build errors.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
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