Slice it vertically and ship in stages rather than building three layers in parallel. Start with the data model and an additive migration, then the API with contract tests, then the UI behind a feature flag. Get one narrow case working end to end early, because that is where wrong assumptions surface cheaply. Keep pull requests small enough that someone can review them properly in one sitting.
Why interviewers ask this
The interviewer wants to know how you decompose work and collaborate, since most delivery problems are sequencing problems rather than coding problems. They are listening for a thin end to end slice first, for how you avoid blocking a teammate on an API contract, and for how you keep changes reviewable. This also predicts whether you will disappear for two weeks and return with an unreviewable pull request.
How to structure your answer
- Clarify the requirement and the smallest useful version.
- Sequence the work bottom up but ship a thin slice end to end first.
- Explain how you unblock parallel work with a contract.
- Describe how you split it into reviewable pull requests.
Example answer
Before writing anything I want the smallest version that is genuinely useful, because half of what gets specced is not needed in the first release. Then I do a thin vertical slice: one field, one endpoint, one screen, working end to end in a day or two. That is where you find out the data model is wrong, and finding it on day two costs nothing compared to day nine. Migrations go first and are always additive so they can ship ahead of the code that uses them. If someone else is building the UI, we agree the API contract early and they work against a mock or a typed schema so nobody is blocked waiting on me. Pull request wise, I aim for changes a reviewer can hold in their head: migration and model in one, endpoint and tests in another, UI in a third, all merged behind a flag that is off. Then we turn it on internally, then for a small percentage. Shipping dark like that has saved me more than once when the load was worse than expected.
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See how it worksFollow-up questions to expect
- What do you do when the requirements change halfway through?
- How do you handle a migration that another team depends on?
- How do you keep a two week feature from becoming one giant pull request?
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