A Claude session generates a database migration, then in the same session is asked to "carefully review the migration for bugs." The review rarely finds anything, but subtle bugs keep reaching staging. What change most improves the review?

Answer: A — Have a separate instance with none of the generator's context review it

A session that generated the code retains its reasoning and is less likely to question its own decisions. An independent instance without that context is more effective at catching subtle issues. Extended thinking (b), a persona instruction (c), and repeated self-review (d) all run over the same anchored context.