edge-cases_skill

Overview

This skill analyzes a Product Requirements Document (PRD) to find edge cases, failure modes, race conditions, and scenarios that might be missed. It turns each finding into concrete PRD updates: acceptance criteria, new user stories, functional requirement changes, or technical notes. Use it after drafting a PRD to harden scope and reduce surprises during implementation.

How this skill works

I read each user story and functional requirement, then apply a structured checklist across input, state, user behavior, error handling, data, security, and performance categories. For every identified edge case I rate severity (Critical/High/Medium/Low) and propose a specific PRD update: new acceptance criteria, a new story, or a technical consideration. The output is a prioritized list of edge cases with actionable recommendations ready to integrate back into the PRD.

When to use it

• After drafting a PRD to validate completeness
• Before handoff to engineering or sprint planning
• When preparing acceptance criteria for complex flows
• Prior to a design review or security assessment
• When migrating data or changing schemas

Best practices

• Apply the category checklist to every user story rather than ad-hoc reviewing
• Prefer specific examples (e.g., >255 chars, 10k items, network timeout of 30s) in acceptance criteria
• Rate severity and focus fixes on Critical/High first
• Group and deduplicate similar edge cases to avoid creating noise
• Include implementation notes (locking, retries, transactions) with any high-severity item

Example use cases

• Find race conditions in an edit/save workflow and add optimistic locking user story
• Identify validation holes (empty/null/invalid formats) and add server-side acceptance criteria
• Surface performance edge cases for large datasets and recommend pagination/streaming
• Detect security risks (XSS, auth expiry) and add sanitization and session-handling requirements
• Create new stories for data migration and legacy-data handling during schema changes