Own decoded node columns, attributes and parent validity once for web, Electron and SVG interpretation. Reject dangling, self and cyclic parent facts; preserve source positions and independently unknown fields. Remove fallback conversions and duplicated string/attribute interpretation.
Validation: baseline public CLI controls failed for four malformed cases with valid control passing; final 103 focused checks, 5 final built CLI controls, 1 late-detach cancellation control (20 skipped), check:fast and docs:check passed. Fake CDP producers and generated local files; no real browser/Electron or Windows qualification.
Refs #4709