Conciseness

The body is dense and assumes Claude's competence throughout, but Phase A item 3 inlines ~180 words of runner-selection fallback rules ("If the Task tool rejects a configured entry… A refused composer-* entry runs on… If it rejects a default, use the closest valid slug…") that could be trimmed or moved. Matches the 4 anchor (minor over-explanation that could be trimmed); not 3, since nothing explains concepts Claude already knows.

Actionability

Concrete specifics throughout — exact model slugs, the "arena runners" line in ~/.cursor/rules/pstack-models.mdc, output paths like /tmp/arena-<slug>/candidate-<n>/, and spawn parameters (run_in_background: true). Instruction-only without code, which the rubric does not penalize, but there is no example candidate prompt or judge prompt template — minor gaps matching 4, not the copy-paste-ready coverage of 5.

Workflow Clarity

Six clearly labeled phases (Frame, Fan out, Cross-judge, Pick, Graft, Verify) with a todolist-per-phase checklist instruction, dropout handling ("If a candidate produces no output, proceed with N-1"), disagreement resolution in Phase D, and Phase F verification with explicit feedback loops ("reframe and re-run rather than averaging the divergence", "go back to Phase E"). Matches the 5 anchor: explicit validation steps, feedback loops, and a checklist.

Progressive Disclosure

Sections are well-organized and all external references (the Claude Code adapter doc, pstack-models.mdc, poteto-mode, the principle skills) are one level deep and clearly signaled. The dense inline runner-fallback logic in Phase A is material that arguably belongs in a separate reference file — a minor organization gap matching 4 rather than 5.

Specificity

Lists three concrete actions covering the entire workflow — "Spawn N parallel candidates at the same task, pick a base, graft the strongest parts of the losers into it" — matching the comprehensive-coverage anchor. No coverage gaps to drop it to 4.

Completeness

Explicitly answers both what (spawn/pick/graft) and when ("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"). The "Use for" clause is an explicit trigger equivalent, so the missing-when cap at 3 does not apply.

Trigger Term Quality

"Use for /arena, 'arena this', 'throw it in the arena'" captures the natural user phrasings plus the command form, and the situational trigger "when one attempt at a non-trivial artifact would lock in the wrong shape" adds another natural entry point. Comprehensive synonym coverage for this domain, matching the 5 anchor rather than 4.

Distinctiveness Conflict Risk

"Arena" is a clear niche with distinct quoted trigger phrases unlikely to match any other skill's description. Minimal overlap risk, matching the 5 anchor; not 4 since no closely related skill would fire on these terms.