Code migration is one of the toughest challenges engineers face at scale. In this episode, we dive deep into a real-world code migration that powered millions of queries daily.

You’ll hear how Sourcegraph rebuilt their core parser, the testing strategies that prevented disasters, and why “unglamorous engineering” is often the work that matters most. From differential testing to temporary safety nets, this story shows how code migration can be done without breaking everything.

Whether you’re planning a refactor, facing a large-scale rewrite, or just curious about engineering under pressure, the lessons here will help you approach your next code migration with confidence.

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