UsdLayerManager/openspec/changes/undo-redo-scene-editing/specs/undoable-attribute-edits/spec.md

ADDED Requirements

Requirement: Generic attribute set is undoable

The system SHALL push an AttributeSetCommand to CommandHistory when PropertyManager::SetPropertyValue or SetPropertyValueInLayer is called. The command SHALL capture the old value (read before the set) and the new value as std::function<void()> closures so it is type-agnostic. Undo() SHALL restore the old value; Redo() SHALL re-apply the new value.

Scenario: Undo reverts attribute change

• WHEN the user changes a light's intensity via the Property panel and then presses Ctrl+Z
• THEN the intensity returns to its previous value

Scenario: Redo re-applies attribute change

• WHEN the user undoes an attribute change and then presses Ctrl+Y
• THEN the attribute is set back to the edited value

Requirement: Attribute command preserves layer targeting

The AttributeSetCommand SHALL record which SdfLayerHandle was the active edit target. Undo() and Redo() SHALL use UsdEditContext to direct the attribute write to that same layer.

Scenario: Undo writes revert to correct layer

• WHEN the user edits an attribute with a non-root layer selected and then undoes
• THEN the revert opinion is written to the same non-root layer, not the root layer