Type definitions mirror runtime

Public type definitions (TypeScript, JSDoc, etc.) must precisely reflect the actual runtime contract of the API — no more permissive, no more restrictive, and no exposing capabilities that don’t actually exist.

• Parameter and return types should match what the implementation actually accepts/produces. If a function coerces its arguments (e.g. via String(x)), type the parameter as unknown/any rather than string, since restricting it to string[] is misleading when any value works at runtime.
• Only expose properties/methods on an interface if they are genuinely available on that object at runtime. For example, if supportsColor only exists on the top-level default export and not on chained instances (chalk.red.supportsColor), it must not be declared as part of the shared Chalk interface — otherwise consumers get false type-checking guarantees. If such a property should logically exist everywhere, fix the runtime implementation first, then update the types to match.
• For fluent/chainable APIs, prefer this as the return type over the concrete class/interface name:

  rgb(r: number, g: number, b: number): this; // preferred
  // rgb(r: number, g: number, b: number): Chalk; // avoid
  

  This keeps subclassing and chaining type-safe and matches what the TS compiler itself generates.

• Extract shared shapes (e.g. ColorSupport, ChalkConstructor) into their own named interfaces instead of duplicating inline object types, improving readability and reuse.
• When keeping deprecated types/exports for backward compatibility, mark them clearly with @deprecated and a TODO noting removal in the next major version, so the deprecation has a concrete lifecycle instead of lingering indefinitely.

Treat the type definitions as a contract: any mismatch between declared types and actual behavior is a bug that should be fixed in either the runtime code or the types, never left inconsistent.