code-reusabilitylisted

# Code Reusability Skill When active, scan the code in context for duplication and reusability gaps, then apply the appropriate pattern. For a full codebase-wide audit, use the `code-reviewer` or `architecture-reviewer` agents instead. ## What to Look For - Same logic copied in two or more places: extract to shared function or module - Same validation rule written per handler: extract to single validator - Same constants or thresholds defined in multiple files: move to single config or constants module - Similar functions differing only by one value or type: parameterize or generalize - Same object construction repeated inline: extract to factory or builder - Same error mapping repeated per handler: extract to shared mapper - Same test setup repeated per file: extract to shared factory or fixture ## Patterns to Apply | Signal | Pattern | |--------|---------| | Same logic in 2+ places | Extract function / Extract module | | Same logic with minor variation | Parameterize: add argument instead of copying | | Same group of values always together | Introduce value object or struct | | Same multi-step process repeated | Extract class or service | | Same conditional type-switching | Replace with polymorphism or strategy | | Same object built ad-hoc everywhere | Factory or builder function | | Same config value hardcoded in N places | Named constant or config key | ## Rules - Extract only when duplication is confirmed: two instances minimum before extracting - Do not over-abst