Systematic Code Review Skill

Systematic 4-phase code review: UNDERSTAND changes, VERIFY claims against actual behavior, ASSESS security/performance/architecture risks, DOCUMENT findings with severity classification. Each phase has an explicit gate that must pass before proceeding because skipping phases causes missed context, incorrect conclusions, and incomplete risk assessment.

Instructions

Phase 1: UNDERSTAND

Goal: Map all changes and their relationships before forming any opinions.

Step 1: Read CLAUDE.md

• Read and follow repository CLAUDE.md files first because project conventions override default review criteria and may define custom severity rules, approved patterns, or scope constraints.

Step 2: Read every changed file

• Use Read tool on EVERY changed file completely because reviewing summaries or reading partial files misses dependencies between changes and leads to incorrect conclusions.
• Map what each file does and how changes affect it.
• Check affected dependencies and identify ripple effects because changes in one file can break consumers that aren't in the diff.

Step 3: Identify dependencies