How to Keep Amazon Kiro Specs in Sync as a Project Grows

The first spec is easy. The failure mode comes three sprints later, when the code has moved and the spec has not. Then Amazon Kiro starts generating against a document that no longer describes your app.

Why do specs drift?

Because code gets urgent and docs get skipped. A hotfix ships without a spec edit, then another, and within weeks the requirements file describes version one while the repo runs version four. Kiro uses the spec as context, so stale specs quietly produce worse code — it is not a loud error, just a slow decline in relevance.

How do you keep a spec current?

• Edit the spec first: when a requirement changes, update the spec before the code.
• Review specs in the PR: treat the requirements file as reviewable as any source file.
• Version the spec: keep it in the repo so its history matches the code’s.
• Trim ruthlessly: delete requirements that no longer apply rather than leaving them as noise.

How do you structure specs for a large project?

Do not keep one giant spec. Split by feature area — auth, billing, search — each with its own requirements, design, and task list. Smaller specs stay readable, are easier to review, and give the agent tighter context. When a feature is done, archive its spec rather than letting it bloat the active set.

What does this cost in practice?

Maintaining specs is a real overhead — budget a fixed slice of each sprint for doc updates, not an infinite polish. The payoff is that AI-generated code stays aligned with intent, which cuts rework. Teams that skip maintenance and then blame the AI for producing irrelevant code have usually let the spec rot, not hit a model limit.

When is a spec not worth it?

Prototypes, throwaway scripts, and spike work do not need a maintained spec. If the code will be deleted in a week, write it directly. Kiro rewards planning on durable systems and slows you down on disposable ones — pick the mode to match the work. If your project is a quick tool, a chat-based editor like Cursor is the lighter choice.

Quick Summary

• Stale specs silently degrade the code Kiro generates.
• Update the spec before the code and review it in pull requests.
• Keep specs in the repo and version them alongside source.
• Split large projects into per-feature specs; archive finished ones.
• Skip specs for prototypes; maintain them for durable systems.