Helix: The internal tool powering our Shopify app's native migration

Shopify rebuilds its mobile app with AI models in small steps, each checked by tests, a visual comparison and two reviewing agents before an engineer approves it.

Shopify is rebuilding its largest mobile app, which has more than 300 screens, in separate native code for iPhone and Android instead of shared React Native code. AI models can do the rewriting, but tools that rebuild a whole feature at once leave the engineer a large amount of code to test. Talha Naqvi of Shopify Engineering describes Helix, the internal tool the team built to break the work into small, checked steps.

• An engineer points Helix at a screen, and Helix proposes a sequence of small steps, each described in a few words, which the engineer approves in minutes.
• Each step passes four checks in order. Tests confirm the behaviour, an AI model compares screenshots with the old app, two separate AI reviewers check the code, and an engineer approves.
• The agent can retry a failed check as often as it needs, but it cannot override one. Engineer feedback is stored, so later steps need less oversight, and an engineer can let Helix run without approvals while the checks still apply.
• The team says the same method works for new features, with designs and product documents as the reference in place of an old app.

Checks that run before a person looks leave the reviewer small, tested pieces to judge instead of one large change. The author makes this point for engineers, and its application to design and product review is an inference.

Derived by Working Surface from the article. Source line: An attempt is allowed to be wrong. It is not allowed to ship until it isn't.

23 September 2026: people keep up with agent-built work when it arrives small and already checked, and when they have learned to judge it.