cross-review

# cross-review — independent verification The implementer never signs off on its own work — a different model does, and review is a sub-agent that returns a structured report, not a transcript anyone needs to read through. ## Procedure 1. Get the task's diff — `sys_os_shell("gh pr diff <pr>")` (or `git -C .worktrees/<task_id> diff main...HEAD`). 2. Run the deterministic gates first — tests / lint / typecheck via `sys_os_shell`. If red, re-dispatch the implementer to drive it green first; don't involve the reviewer yet. If a pytest result's count must be recorded or reconciled, collect ground truth with `python -m pytest --collect-only -q <same files>` against the exact file set/command/commit the implementer reported. Never use `grep -c 'def test_'` as a pytest count: it counts functions, not collected cases, and misses parametrized case expansion. 3. Dispatch a DIFFERENT-vendor sub-agent as reviewer: pick any AVAILABLE worker whose vendor differs from the implementer's — `claude_code`, `codex`, `opencode`, `cursor`, `hermes`, or `pi` (e.g. Claude built it → any of `codex` / `opencode` / `cursor` / `hermes` / `pi`, and so on). Use a task-based title such as `review-auth-refactor`, never the raw vendor name: `sys_session_send(agent="claude_code"|"codex"|"opencode"|"cursor"|"hermes"|"pi", title="review-<task_slug>", args={purpose: "review", input: "<the diff> + <the acceptance contract>. Review ONLY against the contract. Report blo...