Complex sibling list-unit fragments can still round-trip as one wrapper list when each unit stays proved

What happened

After proving one complex list-item unit at a time, the next honest step was:

• two sibling list-item units
• each unit containing:
  • a paragraph
  • a nested list
  • a quote

The question was whether selection across both sibling units still extracts and round-trips as one coherent wrapper-list fragment.

What fixed it

It did not need a new seam.

The current model already held:

• each list-item still behaves as one proved wrapper unit
• selection across the sibling units extracts a bulleted-list fragment that contains those sibling units
• real clipboard paste round-trips that wrapper list through DOM and Chromium

Why this works

The decisive boundary is still the wrapper unit.

If each sibling unit is already a proved shape, crossing multiple sibling units does not automatically create a new architecture seam.

The fragment simply lifts one level:

• one proved unit becomes one proved sibling
• multiple proved siblings become one proved wrapper-list fragment

Reusable rule

Before inventing a new multi-unit transform seam, ask:

• are the sibling units themselves already proved?
• does the fragment simply become a wrapper list of those units?

If yes, prove it through DOM and browser before reaching for new machinery.

Related issues

• 2026-04-05-list-unit-fragment-proofs-should-treat-list-item-fragments-as-sibling-units-and-assert-real-paste-landings.md
• 2026-04-05-wrapper-units-can-expand-from-paragraph-plus-list-or-quote-to-paragraph-plus-list-plus-quote-without-a-new-insert-seam.md