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Refactor vs Rewrite Decision

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Your question is Refactor vs Rewrite Decision. Take a moment with it on the right.

Talk me through your thinking if you like. When you're confident, submit your answer and I'll grade it like a real screen (7/10 or better passes).

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Problem

Scenario

You are evaluating an aging core service that still powers an important part of a B2B SaaS platform. The system has accumulated technical debt, delivery speed is slowing, and reliability issues are starting to affect adjacent teams, but it also contains years of business logic that would be expensive to rediscover. You need to decide whether to refactor incrementally, rewrite the system, or continue investing in the current architecture for now.

Question

How do you decide whether to refactor, rewrite, or keep investing in an existing system?

What Makes This Hard

  • Technical debt is real, but so is the risk of losing embedded business logic.
  • The system is business-critical, so disruption costs are high.
  • Different stakeholders will prefer different answers for valid reasons.
  • The right choice depends on evidence, not engineering instinct alone.