Migrates JS to strict TypeScript with proper types, interfaces, and JSDoc.
Convert the following JavaScript code to TypeScript. Requirements: 1. Add proper types for all variables, parameters, and return values 2. Use interfaces or type aliases for complex objects 3. Use enums where appropriate (don't overuse them) 4. Make it strict — no 'any' types unless absolutely necessary 5. Add JSDoc comments for exported functions 6. Note any type assertions you had to make and why JavaScript code: [PASTE JS CODE HERE]