harness-design

name	harness-design
description	Produce a slice-level detailed design doc at <work_item_dir>/design/<slice_slug>.md by mapping slice responsibilities, interfaces, edge cases, and tests to the work item requirements.
examples	["$harness-design docs/exec-plans/current/gradebook-overrides slice=late-penalty-ui","$harness-design docs/exec-plans/current/platform-modernization/gradebook-overrides slice=late-penalty-ui"]
when_to_use	["PRD/FDD exist and one implementation slice needs deeper design.","A planned phase needs concrete signatures and edge-case handling before coding."]
when_not_to_use	["Task is feature-level architecture (use $harness-architect).","Task is immediate implementation (use $harness-develop)."]

Required Resources

Always load before writing:

• references/design_checklist.md
• references/definition_of_done.md
• references/validation.md
• assets/templates/design_slice_template.md
• <work_item_dir>/prd.md
• <work_item_dir>/fdd.md
• <work_item_dir>/plan.md when present

Workflow

1. Resolve the work item directory.
2. Create or update <work_item_dir>/design/<slice_slug>.md.
3. Use assets/templates/design_slice_template.md as the structure.
4. Map the slice back to the work item requirements and implementation plan.
5. Use repository-local testing and operations docs plus harness.yml to decide which cross-cutting concerns need to be called out.
6. Resolve <skills_root> as the directory that contains the installed harness skills (design/, validate/, etc.). Do not resolve script paths relative to the repository or current working directory.
7. Run python3 <skills_root>/validate/scripts/validate_work_item.py <work_item_dir> --check design --file <work_item_dir>/design/<slice_slug>.md.