Flatten / Transform a Nested Block Tree

Problem

Docs are trees of blocks. Given a nested block structure, flatten it to an ordered list (with depth), or move a block subtree to a new parent preserving order.

Example

blocks tree -> ordered [(block, depth)]; move(subtree, newParent)

Constraints

• Arbitrary nesting; preserve sibling order

What evaluators look for

Practical coding in JS/TS over a real data model. Handle edge cases (move into own descendant).