Harness Designing Plugin helps design teams turn their scattered AI setup — Notion prompts, Figma comments, AGENTS.md rules, chat histories — into a five-layer design harness that compounds across sessions and rotations. Four skills walk you through the assembly: • /hd:learn — Q&A about the five-layer concept (Context Engineering, Skill Curation, Workflow Orchestration, Rubric Setting, Knowledge Compounding) • /hd:setup — detects existing harness artifacts, pre-analyzes all five layers in parallel (5× harness-auditor + rubric-recommender), then walks you through link / critique / scaffold / skip per layer • /hd:maintain — captures lessons and promotes them to team rules in AGENTS.md with SHA-256 plan-hash proof-of-consent • /hd:review — audits harness health in a 2-batch parallel dispatch (5 layer-specialist agents + 2–3 context agents); critiques harness artifacts against quality rubrics Ships 9 sub-agents and 14 starter rubrics (distilled from pbakaus/impeccable, Nielsen's 10 heuristics, Material 3, Fluent 2). Each rubric carries a Scope & Grounding section with personas, user stories, realistic scenarios, and anti-scenarios. Validated across a six-repo pilot matrix. This plug-in is the companion toolkit to Bill Guo's Substack series on design harnessing. Structural inspiration: EveryInc/compound-engineering-plugin.