LocalGridScope

Carries the innermost Grid's Compose GridScope down the tree, or null when no ancestor Grid has provided one — read by Modifier.size() to resolve a child's Span sizing behavior (row/column span placement). Provided by GridTileRenderer; unlike LocalColumnScope/LocalRowScope/LocalLazyItemScope, no other container renderer resets this back to null, so it keeps propagating through any descendant subtree until another Grid provides a fresh value.