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From pm-skills
Documents edge cases, error states, boundary conditions, and recovery paths for a feature. Use during specification for failure coverage or QA planning for test scenarios.
npx claudepluginhub product-on-purpose/pm-skills --plugin pm-skillsHow this skill is triggered — by the user, by Claude, or both
Slash command
/pm-skills:deliver-edge-casesThe summary Claude sees in its skill listing — used to decide when to auto-load this skill
<!-- PM-Skills | https://github.com/product-on-purpose/pm-skills | Apache 2.0 -->
Identifies edge cases that disproportionately affect users with disabilities, including input, output, content, context, and timing scenarios. Use when reviewing designs for completeness or planning test cases.
Creates Given/When/Then acceptance criteria from a user story or feature slice, covering happy path, failure scenarios, and non-functional expectations for engineering and QA handoff.
Explores edge cases across 12 dimensions like invalid input, concurrency, and auth failures. Scores scenarios by likelihood x impact. Generates runnable tests for high-risk ones.
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An edge cases document systematically catalogs the unusual, boundary, and error scenarios for a feature. While happy-path flows are typically well-specified, edge cases often get discovered in production - causing bugs, poor user experience, and support burden. Documenting edge cases upfront ensures engineering handles them intentionally and QA knows what to test.
deliver-acceptance-criteria; this skill catalogs the whole feature's failure surfacedeliver-prd firstiterate-lessons-log, then update this catalog with the new casedeliver-launch-checklistWhen asked to document edge cases, follow these steps:
Define the Feature Scope Clearly describe what feature or flow you're analyzing. Edge cases are specific to context - the same input might be valid in one feature and invalid in another.
Walk Through Input Validation Consider every user input: What if it's empty? Too long? Wrong format? Contains special characters? What are the minimum and maximum valid values?
Explore Boundary Conditions Find the edges of acceptable ranges. If a field accepts 1-100, test 0, 1, 100, and 101. Consider pagination boundaries, timeout thresholds, and rate limits.
Map Error States Identify what can go wrong: network failures, permission denied, resource not found, concurrent modifications, expired sessions. Document both the scenario and expected behavior.
Consider Concurrency Issues What if two users act simultaneously? What if the user double-clicks? What if data changes between load and save? Race conditions often cause subtle bugs.
Define Recovery Paths For each error, specify how users recover. What message do they see? Can they retry? Is data preserved? Good error handling turns frustration into confidence.
Prioritize by Likelihood and Impact Not all edge cases need the same attention. High-likelihood + high-impact cases need robust handling; rare + low-impact cases might just need graceful failure.
Use the template in references/TEMPLATE.md to structure the output. A complete edge-case catalog fills every template section: Feature Overview; Edge Case Categories; Error Messages; Recovery Paths; and Test Scenarios.
Before finalizing, verify:
See references/EXAMPLE.md for a completed example.