Documents edge cases, error states, boundary conditions, race conditions, and recovery paths for a feature - the systematic catalog of what can go wrong and the failure modes to design for. Use during specification to map the failure surface and ensure comprehensive coverage, or during QA planning to identify boundary and limit scenarios to test.
Install
npx skills add product-on-purpose/pm-skills --skill deliver-edge-casesnpx skills add product-on-purpose/pm-skills --skill deliver-edge-cases -a claude-code -gnpx skills add product-on-purpose/pm-skills --skill deliver-edge-cases -a codex -ggemini skills install https://github.com/product-on-purpose/pm-skills.git --path skills/deliver-edge-casesgh skill install product-on-purpose/pm-skills deliver-edge-casesgit clone --depth 1 https://github.com/product-on-purpose/pm-skills /tmp/product-on-purpose__pm-skills
mkdir -p ~/.claude/skills ~/.agents/skills
cp -R /tmp/product-on-purpose__pm-skills/skills/deliver-edge-cases ~/.claude/skills/deliver-edge-cases # Claude Code
cp -R /tmp/product-on-purpose__pm-skills/skills/deliver-edge-cases ~/.agents/skills/deliver-edge-cases # Codex, Cursor, Gemini CLI, Copilot, OpenCode