input-validation-preconditions

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.