AI & Technical question
You inherit a public API used by enterprise customers and partners, and a cleaner resource model would require a breaking change to both response schemas and webhook payloads. How would you decide whether to make that breaking change at all, and if you did, what versioning, deprecation window, migration tooling, and customer communication plan would you put in place?
- Glean
- AI & Technical
- Hard
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What this question tests
Whether you can weigh a breaking API change against real customer and partner cost, and if you proceed, design the versioning and migration plan that protects existing integrations.
How to approach it
- Decide whether the breaking change is truly necessary first: quantify the cost of not making it, like ongoing engineering burden from workarounds, versus the cost of making it, like partner integration rework and support load.
- Consider a non-breaking alternative before committing to a break: an additive new resource model alongside the old one might solve the underlying cleanliness problem without forcing a hard migration.
- If proceeding, version explicitly, for example a new API version namespace, keeping the old version fully functional in parallel rather than a hard cutover.
- Set a deprecation window long enough for typical enterprise release cycles, and build migration tooling, like a schema-diff tool or a compatibility shim for the webhook payload, to reduce partner engineering burden.
- Communicate proactively and specifically: notify affected customers and partners early with a clear timeline, concrete migration guide, and a support channel for the transition, rather than a generic changelog note.
What a strong answer includes
- Considers a non-breaking alternative before defaulting to the breaking change, showing real discipline about API stability for external partners.
- Proposes concrete migration tooling, like a compatibility shim, not just documentation, which is what actually reduces partner burden.
- Ties the deprecation window to typical enterprise release cycles, reflecting how partners actually plan migrations, rather than picking an arbitrary timeframe.
Common mistakes
- Commits to the breaking change without first evaluating a non-breaking alternative.
- Plans a hard cutover with a short deprecation window, underestimating the real burden on enterprise partners.
Likely follow-up questions
- How would you handle a partner who cannot migrate within the deprecation window.
- What would you do if usage data shows many customers still on the old version near the cutoff date.
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Learn the skill behind it
Chapters of the AI PM course that teach what this question tests.
- Chapter 1: Foundations: the model and the decisions it forces on you
- Chapter 8: Evals: define good and make the number defensible
- Chapter 6: Agents and agentic architecture