6 Software Migration Lessons from Shopify's 12-Week AI-Assisted Rewrite

Описание и применение

Shopify в 12 недель перенес мобильное приложение на новый стек, используя AI‑агентов, доказав, что AI может сократить сроки миграции, если соблюдать дисциплину: использовать старую систему как спецификацию, проверять поведенческую параллельность, контролировать планы и держать людей в процессе проверки.

Задача

Legacy systems often remain unmodernized due to perceived high cost and complexity, delaying necessary upgrades.

Результат

Shopify completed a major app rewrite in 12 weeks, achieving behavioral parity, reducing duplication, and simplifying the codebase, all while maintaining human oversight.

Рабочий процесс

• Revisit shelved migrations to reassess cost
• Document legacy behavior as the spec
• Build parity checks between old and new systems
• Obtain human approvals tied to content hashes
• Run AI agents in parallel lanes with fast feedback loops
• Simplify and retire unused features during migration
• Plan gradual rollout with feature flags and rollback

Доказательства

A team of six at Shopify moved a major production app to a new stack in 12 weeks, with AI coding agents doing most of the porting.

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Shopify found that agents work best when there's an existing implementation to use as a reference.

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Shopify built an internal tool that captured outputs from both the old and new systems at named checkpoints.

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Engineers reviewed requirements and plans before any code was written, and each approval was tied to a content hash.

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Shopify ran many agent sessions at once, each in its own git worktree, instead of making one change at a time.

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