Benchmark: work-with-pr (Iteration 1)

Summary

Metric	With Skill	Without Skill	Delta
Pass Rate	96.8% (30/31)	51.6% (16/31)	+45.2%
Mean Duration	340.2s	303.0s	+37.2s
Duration Stddev	169.3s	77.8s	+91.5s

Per-Eval Breakdown

Eval	With Skill	Without Skill	Delta
happy-path-feature-config-option	100% (10/10)	40% (4/10)	+60%
bugfix-atlas-null-check	100% (6/6)	67% (4/6)	+33%
refactor-split-constants	100% (5/5)	40% (2/5)	+60%
new-mcp-arxiv-casual	100% (5/5)	60% (3/5)	+40%
regex-fix-false-positive	80% (4/5)	60% (3/5)	+20%

Key Discriminators

• three-gates (CI + review-work + Cubic): 5/5 vs 0/5 — strongest signal
• worktree-isolation: 5/5 vs 1/5
• atomic-commits: 2/2 vs 0/2
• cubic-check-method: 1/1 vs 0/1

Non-Discriminating Assertions

• References actual files: passes in both conditions
• PR targets dev: passes in both conditions
• Runs local checks before pushing: passes in both conditions

Only With-Skill Failure

• eval-5 minimal-change: Skill-guided agent proposed config schema changes and Go binary update for a minimal regex fix. The skill may encourage over-engineering in fix scenarios.

Analyst Notes

• The skill adds most value for procedural knowledge (verification gates, worktree workflow) that agents cannot infer from codebase alone.
• Duration cost is modest (+12%) and acceptable given the +45% pass rate improvement.
• Consider adding explicit "fix-type tasks: stay minimal" guidance in iteration 2.