Function validate_tree_delta 

pub fn validate_tree_delta(
    value: &Value,
    limits: &Limits,
) -> Result<(), ValidationError>

Validate the SHAPE of a tree-delta message.

Only the shape is checkable here. A delta carries no columns/rows, so whether a parent exists, whether the tree stays acyclic and inside the depth ceiling, and whether bounds or the cursor fall within the viewport can only be judged once the delta is applied to its base — put the assembled tree through validate_snapshot for that.

What is checkable without the base: sizes, node shape, unique ids, a revision that moves forward, and the same id never both upserted and removed by one delta.

Errors

Returns a ValidationError whose code matches the reference.