Perform exact-revision, read-only merge-gate reviews with explicit verdicts

When conducting correctness or security merge-gate reviews, use only the user-specified immutable BASE and HEAD revisions and verify their identities, trees, and patch integrity as requested. Never inspect or modify the worktree, substitute revisions, or mutate repository state; rely on immutable Git object commands and evidence. After restarts, resume the existing assignment while preserving all prior constraints and reverify the target when required. Produce a substantive, non-empty, findings-first report with precise file-and-line evidence, defects or blockers, regression guidance, scope, and residual risks. Treat empty reviewer output as invalid and replace it when instructed. Await active reviewers through completion notifications without polling or duplication. End every review report with exactly MERGE or DO-NOT-MERGE, and do not merge unless every specified review and repository-state gate passes.