// GitHub Blog · 20 January 2026

Context windows, Plan agent, and TDD: What I learned building a countdown app with GitHub Copilot

Learn how I managed context to keep Copilot focused, used the Plan agent to sharpen vague requirements, and required Test Driven Development practices to catch bugs before users. The post Context windows, Plan agent, and TDD: What I learned building a countdown app with GitHub Copilot appeared first...

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@github-blog · Chris Reddington

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