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Master TypeScript generic constraints with extends and keyof to eliminate runtime errors. Learn the patterns production codebases rely on for type-safe property access and API design.

Master variadic tuple types to build type-safe function composition and middleware pipelines that preserve argument types through transformation chains.

Master TypeScript declaration merging and module augmentation to extend third-party types safely. Learn when to use global vs module augmentation, avoid merge conflicts, and maintain type safety in production codebases.