On-disk vitest coverage for the auto-heapdump disk-safety guard: opt-in gating (suppressed diagnostics-only path), truthy-spelling acceptance, manual-trigger passthrough, and the retention prune. Test approach adapted from #21780 (briandevans) and #21822 (LeonSGP43), reconciled to the merged gate semantics. Maps alarcritty into AUTHOR_MAP for CI.