This skill should be used when the user says "review plan", "validate plan", "check plan", "sanity check the plan", "verify plan", "review my plan", "audit plan", "is my plan ready", or wants to validate a structured project plan for completeness, correctness, and pattern compliance before execution. Checks structural completeness, document quality, dependency graph consistency, codebase reference validity, and pattern compliance. Offers to fix found issues interactively and can proceed directly to arn-code-taskify when the plan passes.