One-shot second-opinion diff review by a different-model seat, advisory only

Notes & tips

• Same-diff runs across two seats are cheap comparative evidence — the T3 dogfood used exactly that pairing to test the default.
• The board thread id (review-<branch-slug>-<stamp>) is in every result; findings worth keeping go through the roundtable promotion flow, since board threads are TTL'd and the ledger row is what endures.
• Reviewing another branch: check it out in a detached scratch worktree and pass that worktree as repo_root — the resolver reviews whatever HEAD is.