AIが生成したコードにレビューが必要な理由

AI assistants produce code that reads cleanly and runs on the happy path. That polish is exactly the danger: fluency is not correctness.

An advanced vibe coder treats every generated block as a draft from a fast but unaccountable junior. The code compiles, the demo works, and a subtle off-by-one or missing auth check ships to production.

Review is not optional friction. It is the step that converts plausible output into trustworthy software.

Models invent APIs, import non-existent packages, and call methods that were renamed two versions ago. They also confidently mix patterns from incompatible framework versions.

Because the surrounding code looks idiomatic, these errors hide well. A function that calls db.fetchAllUsers() may look fine until you learn that method never existed.

Your first review pass is a reality check against the actual library surface, not the model's imagined one.

Generated functions handle the example you described and ignore the inputs you forgot to mention: empty arrays, null fields, negative numbers, unicode, concurrent writes.

The model optimizes for matching your prompt, not for the full domain of possible inputs. That gap is where production bugs live.

Ask the assistant to surface its own blind spots before you trust the output.

Reviewers are slower to catch bugs in AI code than in human code, because the explanation alongside it sounds authoritative. The model narrates its choices with confidence even when they are wrong.

Train yourself to read the code, not the commentary. A convincing rationale for a flawed approach is still a flawed approach.

Separate what the code does from what the assistant claims it does.

Models reproduce the average of their training data, and the average web tutorial is insecure. Expect string-concatenated SQL, secrets in source, missing authorization, and permissive CORS.

Unless you explicitly ask for hardened code, you get demonstration-grade code. The default is convenience, not safety.

Make security a stated requirement in every prompt that touches data, auth, or user input.

Each AI request optimizes locally. Over many sessions, the codebase accumulates duplicated helpers, inconsistent error handling, and three competing ways to call the database.

No single change looks wrong, yet the system slowly loses coherence. The model has no memory of the conventions it agreed to yesterday.

Periodic architectural review keeps the codebase from fragmenting into a pile of locally-optimal snippets.

The deepest review question is not "does this run?" but "does this do what I actually meant?" Models satisfy the literal prompt, including your imprecise wording.

If you said "delete old records" without defining old, the model picks a threshold. That guess becomes business logic.

Verify that every implicit decision the model made matches your real intent.

A repeatable checklist beats ad-hoc reading. For each generated change, confirm: inputs validated, errors handled, auth enforced, secrets externalized, edge cases covered, and behavior matches intent.

You can delegate part of the checklist to the assistant itself, then verify its answers independently.

Consistency is what turns review from a vibe into a discipline.

When the assistant edits existing code, review the diff, not just the final file. Models sometimes "refactor" by silently dropping a validation, a log line, or a feature flag.

A small requested change can come bundled with unrequested edits. The narrower the diff you accept, the fewer surprises ship.

Insist on minimal, scoped changes and read every removed line.

Review scales when you encode your expectations as tests. Once a behavior is pinned by an assertion, the model cannot quietly break it without the suite turning red.

Generated tests are themselves drafts that need review, but a flawed test caught by a passing-but-wrong run still beats no test.

The next lessons turn this leverage into a workflow.

The assistant has no stake in the outcome. When the app leaks data or charges the wrong card, the responsibility is yours, not the model's.

Mature vibe coding means owning the output as if you typed every character. The AI accelerates you; it does not absolve you.

Review is how you earn the right to ship what you did not write.

Test your understanding of why AI-generated code demands review.

AI code is a confident draft: fluent but unaccountable. It hallucinates APIs, skips edge cases, defaults to insecure patterns, and drifts architecturally over time.

Counter this with disciplined review: read for intent, diff don't trust, run a checklist, and pin behavior with tests. Accountability for what ships stays with you.

Next, you will turn expectations into generated test suites.