Both Mac runtimes pass the original sixteen-case timeline workflow with fixture 2 changed from blank nested what to blank nested when. The verifier asserts exact accepted selection rectangles and actual pointer edits/undo/redo. This corroborates the generic data-opf-source-text fallback; no editor product fix was needed. Review: https://github.com/OpenPresentation/opf-editor/pull/15#discussion_r3984308314