input-validation-preconditionslisted

## Activation Contract Load this skill when reviewing refactor plans for: input validation, preconditions, boundary validation. ## Hard Rules - Validate at system and module boundaries. - Flag implicit assumptions that can fail at runtime. - Centralize duplicated validation only when it represents one business rule. - Do not scatter defensive checks inside pure internals without need. - Preserve observable behavior; label functional changes as follow-up. - Require evidence for every recommendation, or mark it as a hypothesis. ## Decision Gates | Signal | Action | |---|---| | Concrete evidence exists | Create a finding with file, lines, symbol, benefit, validation, and rollback. | | Evidence is incomplete | Mark as hypothesis and lower confidence. | | Recommendation is cosmetic or speculative | Omit it unless maintainability benefit is clear. | ## Execution Steps 1. Inspect the target and nearby tests only as needed for this lens. 2. Identify findings that match this skill's responsibility. 3. Recommend the smallest safe behavior-preserving refactor. 4. Add validation and rollback steps for each recommendation. ## Output Contract Return structured findings for the calling reviewer. Return `no_findings` when this lens has no material issue. ## References None.