Agent skill · product strategy · cursor
arena
Spawn N parallel candidates at the same task, pick a base, graft the strongest parts of the losers into it. Use for /arena, 'arena this', 'throw it in the arena', or when one attempt at a non-trivial artifact would lock in the wrong shape.
Why this skill is useful
Adds a detailed multi-phase workflow for parallel task execution and synthesis that enhances the AI's capability to generate and refine artifacts.
What it needs
About 3k tokens when loaded. Last updated 2026-08-06. 2,555 stars on the source repository.
What this skill does
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. Start Open a todolist with one entry per phase before launching anything. 1. Frame 2. Fan out 3. Cross-judge 4. Pick 5. Graft 6. Verify Phase A: Frame The N candidates will receive 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. 3. Pick the runners. Use the arena runners line in ~/.cursor/rules/pstack-models.mdc. If the rule or that line is missing, default to one each on claude-opus-5-5-xhigh and grok-4.7-xhigh-fast. An auto or inherit-parent entry in this line or the cross-judge line means the parent model, so omit model for it. If the Task tool rejects a configured entry, run that seat on its family's default and say so. Families go by prefix: claude- and grok-. With no family match, use claude-opus-5-5-xhigh. If it rejects a default, use the closest valid slug of the same family from its error message. Spawn more when the arena covers multiple design directions. Same model N times when the work is generation-bound rather than judgment-sensitive. 4. Assign output paths. Each candidate writes to its own location (a git worktree where possible, otherwise /tmp/arena-<slug>/candidate-<n>/), per the separate-before-serializing-shared-state principle skill. Phase B: Fan out Spawn all N subagents in one message with runinbackground: true, 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. …
How to use it
Reference it in AdaL, Claude Code, Cursor or any coding agent — nothing to install:
@skills cursor/arena