arena · diff

git:20261017.8ef3dac to git:20261026.385852f

10 added, 22 removed. Audit A to A.

---

name: arena

description: "Run several candidates at one task, pick a base, graft in the best of the rest, and return one artifact. Use for /arena, \"경쟁시켜줘\", \"여러 버전 만들어서 비교해줘\", or a design where one attempt would lock in the wrong shape. Split-up work ending in a report is swarm."

---

# Arena

Fan out N parallel attempts at the same task. Read every candidate end to end. Pick the strongest as the base. Graft the best ideas from the others into it. Verify the synthesized result.

A **<name>** principle skill below is `references/principle-<name>.md` in the **principles** skill.

## Phase A: Frame

- The N candidates will receive the same prompt, so the prompt is the contract.

+ Every candidate gets the same prompt, so the prompt is the contract.

1. State the artifact each candidate is producing.

- 2. Derive the rubric. State what success looks like for *this* task, then turn it into 3-6 concrete gradeable criteria. The rubric is the picker's tool in Phase D. Candidates only see the task.

+ 2. Derive the rubric, 3-6 concrete gradeable criteria for what success looks like on *this* task. It is the picker's tool in Phase D. Candidates only see the task.

3. Pick available runners suited to the task and authorized environment. Independent attempts

may use the same model. Use the host's supported delegation API and configured defaults;

do not require a particular vendor, model family, plugin, or global installation path.

4. Assign output paths. Each candidate writes to its own location (a git worktree through `isolation: "worktree"` where the artifact lives in the repo, otherwise its own folder in the scratchpad), per the **separate-before-serializing-shared-state** principle skill.

## Phase B: Fan out

- Launch every candidate in one message, each with the task, the path to the shared grounding, its own output path, and instructions to produce both the artifact and a short rationale.

- Each rationale names the alternatives the candidate considered and what it rejected.

+ Launch every candidate in one message, each with the task, the path to the shared grounding, its own output path, and instructions to produce the artifact and a short rationale naming the alternatives it considered and what it rejected.

- If a candidate fails to produce output, proceed with N-1 and note the dropout in the synthesis record.

+ If a candidate produces no output, proceed with N-1 and note the dropout.

## Phase C: Cross-judge

After every Phase B candidate completes, spawn one read-only judge who did not produce the candidates. It sees the rubric and the candidates by path label, scores each criterion, and recommends a base with rationale, while you do your own reading in Phase D.

## Phase D: Pick a base

- Read every candidate end to end before picking.

- Score each candidate against the rubric criterion by criterion, not on holistic feel. Compare against the cross-judge. Agreement on the base confirms the pick. Disagreement means one of you is biased or the rubric was ambiguous. Read both rationales before deciding.

- Pick the base on which candidate a future maintainer can extend most easily without breaking invariants. Prefer the cleaner boundary or smaller API when two feel tied, per the **laziness-protocol** principle skill.

+ Read every candidate end to end before picking. Score each against the rubric criterion by criterion, not on holistic feel, and compare with the cross-judge. Agreement on the base confirms the pick. Disagreement means one of you is biased or the rubric was ambiguous. Read both rationales before deciding.

- Record the pick and the reason in a short synthesis note alongside the base artifact, including the cross-judge's verdict.

+ Pick the base a future maintainer can extend most easily without breaking invariants. When two feel tied, prefer the cleaner boundary or smaller API, per the **minimize-reader-load** principle skill.

## Phase E: Graft

- Walk each losing candidate once more and identify what is worth porting into the base. The signal is usually one or two things per candidate, not most of it.

- Fold each graft in by hand, per the **redesign-from-first-principles** principle skill. Don't paste mechanically. The result has to remain coherent under one mental model.

- Record what was grafted, from which candidate, and what was rejected and why.

+ Walk each losing candidate once more for what is worth porting into the base, usually one or two things per candidate, not most of it. Fold each graft in by hand, per the **redesign-from-first-principles** principle skill, so the result stays coherent under one mental model. Don't paste mechanically.

- When N candidates converge on the same shape, that is a strong agreement signal. Note the convergence in the record and ship the consensus shape. No graft is needed. When N candidates wildly diverge, Phase A was under-specified. Reframe and re-run rather than averaging the divergence.

+ If the candidates converge on one shape, that is strong agreement. Note it and ship the consensus shape. No graft is needed. If they wildly diverge, Phase A was under-specified. Reframe and re-run rather than averaging the divergence.

## Phase F: Verify

- The synthesized artifact has to hold up under the same scrutiny as any other output, per the **prove-it-works** principle skill.

- If verification surfaces a problem the arena did not catch, either Phase A was wrong (re-frame and re-run) or one candidate caught it and you missed the graft (go back to Phase E). Don't paper over.

+ Verify the synthesized artifact like any other output, per the **prove-it-works** principle skill. If verification finds a problem the arena missed, either Phase A was wrong (re-frame and re-run) or a candidate caught it and you missed the graft (go back to Phase E). Don't paper over it.

## Outputs

- One synthesized artifact. One short synthesis note alongside, naming the base, the grafts (with source candidate), the rejections, the dropouts if any, and the verification result.

+ One synthesized artifact, with a short synthesis note alongside naming the base and why, the cross-judge's verdict, each graft with its source candidate, what was rejected and why, any convergence or dropouts, and the verification result.