tier2-handoff

Run a Tier 2 cross-model review handoff on a Tier-1-reviewed chunk of work: gather the bead context, changed files, Tier 1 outcomes, and trusted boundary; draft the review-focus paragraph; call the deterministic assembler to emit a ready-to-paste prompt document for external models; then triage the returned findings (accept/reject with reason, conservative on disagreement) and emit the close-evidence line. Use when the user says "tier 2 review", "cross-model review", "tier 2 handoff", "assemble the review prompt", or when a shared-primitive bead has passed Tier 1 and needs external-model eyes before close.