Reuse the shared validated XML document for depth and prototype-key preflight, preventing recovery-only values from being projected as observations. Preserve OpenStep and valid XML source semantics.
Validation: 46 focused checks; 5 final syntax controls; 10 encoding and public CLI/MCP overlap checks; check:fast. Public malformed-entity CLI changed from success to typed format failure. Generated inert artifacts only; no real Apple application or native engine execution.
Refs #4714