best-of-nlisted

# /best-of-n -- Parallel Implementation Tournament Implement a task multiple different ways in parallel, evaluate all candidates, and apply the best one. ## Usage `/best-of-n [N] <task>` - If the first token is a number 2-10, it sets the candidate count; the rest is the task. - If omitted, N defaults to 3. Examples: - `/best-of-n implement the login page` (3 candidates) - `/best-of-n 5 refactor the auth module` (5 candidates) ## Steps 1. Parse the user's message to extract **N** (candidate count, default 3) and the **task description**. 2. Spawn **N** subagents in a single message (parallel tool calls). Use the `task` tool for each with: - `subagent_type`: `"general-purpose"` - `isolation`: `"worktree"` - `run_in_background`: `true` - `description`: `"Candidate <number>"` - `prompt`: the task description, plus `"You are candidate <number> of <N> independent implementations. Implement the task fully. When done, summarize your approach and the changes you made."` 3. Wait for all candidates to complete using `get_task_output` with `block: true` or `wait_tasks` with `mode: "wait_all"`. 4. Evaluate and pick the winner using the criteria below. 5. Apply the winner's changes from its worktree to the main workspace. Review the changes in context and fix any remaining issues. 6. End your response with `WINNER: <number>` (1-N). ## Evaluation Criteria Evaluate each candidate on these axes, in order of importance: 1. **Correctness** -- Does