Gotcha: TypeScript satisfies operator vs type annotation

Type annotations (: Type) widen the inferred type, losing specific literal types. Need to validate a type without widening.

Use 'satisfies' to validate without widening:

type Colors = Record<string, [number, number, number]>;

// With type annotation - loses specific keys:
const colors: Colors = {
red: [255, 0, 0],
green: [0, 255, 0],
};
colors.red; // [number, number, number] - OK
colors.blue; // No error! string index allows any key

// With satisfies - keeps specific keys:
const colors2 = {
red: [255, 0, 0],
green: [0, 255, 0],
} satisfies Colors;
colors2.red; // [number, number, number] - OK
colors2.blue; // Error! Property 'blue' doesn't exist

// More examples:
type Route = { path: string; exact?: boolean };

const routes = {
home: { path: '/', exact: true },
about: { path: '/about' },
} satisfies Record<string, Route>;

// routes.home.path is string (not widened to Route)
// routes.home.exact is true (not boolean | undefined)
// routes.missing would be an error

// Use cases:
// 1. Config objects: validate shape, keep literal types
// 2. Enum-like objects: validate values, keep specific keys
// 3. Theme objects: validate structure, keep autocomplete

satisfies validates the type at the assignment site while preserving the narrowest possible inferred type, giving you both safety and precision.