cross-review — independent verification

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. Reuse the supplied diff file, or save the task's diff directly with a shell redirect (gh pr diff <pr> > <absolute shared diff path> or git -C .worktrees/<task_id> diff <base-sha>...<head-sha> > <absolute shared diff path>). Use a unique snapshot outside the implementer's worktree, record its base and head commit SHAs, and leave it unchanged until review finishes. The reviewer must be able to read that path. For a different host or sandbox, transfer the snapshot first or arrange access to both commits so it can compute the diff; never regenerate the diff through model output.
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, agy, or pi (e.g. Claude built it → any of codex / opencode / cursor / hermes / agy / 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"|"agy"|"pi", title="review-<task_slug>", args={purpose: "review", input: "Read the diff at <absolute shared diff path> (base <base-sha>, head <head-sha>). <The acceptance contract>. Review ONLY against the contract. Report blocking / non-blocking / suggestions. Do not edit code. If the snapshot is inaccessible, report that failure rather than reviewing from a summary."}). Pass the snapshot path, not its contents; do NOT point the reviewer at the implementer's worktree. Prepare the snapshot and emit the sys_session_send call in the SAME turn you decide to review — never end a turn having only announced "I'll load cross-review and fetch the diff" with no tool call (that dropped turn stalls the run; nothing dispatches and no inbox wake arrives). Once the reviewer dispatch is in flight, end your turn;