Native fallback

Every neuro.* method has two modes, decided at the call site by the presence of a prompt key on the input object:

prompt field	Behaviour
Missing	Calls the native built-in directly.
Empty string ''	Treated as missing - calls the native built-in directly.
Non-empty string	Routes to the configured LLM.

The native fallback is not a fallback in the “the LLM failed, fall back” sense. It is the default. The LLM is opt-in per call.

import { neuro } from 'neuro-ts';

await neuro.array.map({ array: [1, 2, 3], callbackfn: (n) => n * 2 });
// [2, 4, 6]   <- native call, no client needed

await neuro.string.split({ string: 'a,b,c', separator: ',' });
// ['a', 'b', 'c']   <- native

await neuro.object.keys({ o: { a: 1, b: 2 } });
// ['a', 'b']   <- native

Why both?

The native path keeps neuro-ts a strict superset of the standard library. You can wire neuro into existing code, ship it without breaking anything, then sprinkle prompts in only where they help.

It also means neuro-ts works with no OPENAI_API_KEY configured: as long as the input lacks a prompt field, the library is just a typed Promise wrapper over the original built-ins.