Arena: Build It Several Ways, Keep the Best

Outcome Contract

• Outcome: one artifact built from the strongest candidate, improved with the best parts of the others.
• Done when: every candidate is scored on the same rubric, the base and each graft are named with the rubric point they win, and the merged artifact passes its check.
• Evidence: each candidate's output path, the score table, the judge's pick, and the final check output.
• Writes: candidates go to scratch paths outside the repo; only the merged artifact lands in the repo.

Process

1. Frame. Name the artifact, a 3–6 point rubric, the runners (2–4) and each runner's model, and one output location per runner. Mixing model families widens the spread.
2. Fan out. Spawn every runner in one message, in the background, on an identical brief built per work work-fanout.md; only the output path differs.
3. Cross-judge. Score each candidate yourself, then ask a judge for its pick and reasons; a judge on a different model family from the runners is recommended.
4. Pick a base. The highest rubric total wins; on a tie, the simpler candidate.
5. Graft by hand. Copy the best part of each loser into the base, one rubric point at a time; never merge whole candidates.
6. Verify. Run the artifact's check on the merged result.

Candidates that diverge wildly mean the brief was under-specified: reframe the rubric or the brief and re-run; never average them.

Output

Base:     [runner, model, total score]
Grafts:   [from runner → part, rubric point it wins]
Scores:   [table: runner × rubric point]
Judge:    [pick, model, one-line reason]
Check:    [command and result]

Defer to: work (fan-out core and integration), think (when the question is a decision, not an artifact), check (gating the merged result).