Module damage 

Damage + LineDelta — the typed dirty-region boundary.

The second node of escriba’s sealed refresh tree (theory/ESCRIBA.md §X), below EditGen: where EditGen answers did anything change?, Damage answers what region changed? so the renderer can scope its work (re-shape / scissored present) to that region instead of the whole document.

The invariant it seals (S3): Damage ⊇ the actually-changed region. The type only ever widens (the join is a join-semilattice with Full as top), so the producer can be conservative and a consumer that repaints Damage never misses a changed cell. An under-approximation — a changed line the renderer skips — has no constructible path: there is no operation that narrows Damage.

Structs

LineDelta

How the line count changed under one edit — the scope signal a buffer mutation reports up to the refresh tree. start is the first line the edit touched; the counts let a consumer tell an in-place edit (old == new, damage is local) from one that shifted every line below (old != new, damage runs to the end of the document).

Enums

Damage

The dirty region of the document to refresh. A join-semilattice ordered None ⊑ Lines ⊑ Viewport ⊑ Full, so combining two damages always yields one that covers both (never less). Line ranges are inclusive [from, to]; to == u32::MAX means “to the end of the document” (used when an edit shifted every line below it).