Interrogate

Adversaries try to break a change or a design. A finding survives only when a run proves it. Report the findings. Do not apply fixes.

Frame

The scope is what the user names. Otherwise it is the branch diff from its merge base with the base branch, through the working tree. State the intent with the in-your-own-words skill, from the user's message, the commits, and the PR description. Ask the user when the intent is unclear.

Fan out

Run Phase A steps 3 and 4 and Phase B of the arena skill, with four changes. Read the interrogate reviewers line in place of arena runners. With no such line the panel defaults to opus, fable, sonnet, codex. Leave a codex entry for the lane below. Copy the scope's uncommitted changes into each worktree. Spawn each Claude adversary as general-purpose with isolation: "worktree". keel:critic cannot do this, because adversaries write repros and keel:critic cannot edit or write files. In place of the arena task and rationale, give each adversary the scope, the intent, and this brief:

Break this change. Prove each finding with a run against the real code, such as a failing test, a repro script, or command output that shows the wrong behavior. For a design or plan, run a prototype or probe the current tree. Keep repros in your own worktree. Report each finding with a title, the exact command, the output it printed, and the output the intent requires. Leave out anything you did not run. That covers style, naming, structure, and risks that need a future change to matter. No findings is a valid result.

The codex entry is a cross-vendor lane, not a subagent. Run command -v codex first. If it fails, skip the lane and name it as skipped under Dropped. Otherwise start it in the same message as the Claude adversaries, in the background, in its own worktree under $tmp, a scratch directory you create with mktemp -d. Its workspace-write sandbox lets it write there. Write the brief to a file and pipe it in on stdin so every adversary gets the same brief.

git worktree add --detach "$tmp/codex" HEAD
git diff HEAD --binary | git -C "$tmp/codex" apply --allow-empty
codex exec --sandbox workspace-write --ephemeral --cd "$tmp/codex" \
  --output-last-message "$tmp/codex-findings.md" - < "$tmp/adversary-brief.md"

Copy untracked files in the scope by hand, because git diff leaves them out. When the command finishes, read $tmp/codex-findings.md, treat it like any other adversary's report, and remove the worktree with git worktree remove --force "$tmp/codex".

Verify

Verify each finding per arena Phase F by rerunning its command. Keep a finding when the output shows the failure and the failure breaks the intent. Drop the rest. Merge findings that share a root cause.

Skip arena Phases C, D, and E. Adversaries find different failures, so the verdict keeps every verified finding, not one adversary's list.

Output

• Intent: the restatement.
• Findings: for each verified finding, the command, its output, how it breaks the intent, and the adversaries that found it. Say "no verified findings" when none survive.
• Dropped: for each adversary, the count of dropped findings and why.