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concat

Instance method on Array.prototype. Variadic items live under items.

Combines two or more arrays. This method returns a new array without modifying any existing arrays.

concat(input: { array: <receiver>; items: ConcatArray<T>[]; prompt?: string }): Promise<T[]>
concat(input: { array: <receiver>; items: (T | ConcatArray<T>)[]; prompt?: string }): Promise<T[]>

The prompt field is optional. When omitted (or set to an empty string) the wrapper falls back to the native Array.prototype.concat and returns a resolved Promise without contacting the LLM. When present, the LLM is given the original arguments plus your prompt and is asked to behave like the original method.

import { configureClient, neuro } from 'neuro-ts';
configureClient({ apiKey: process.env.OPENAI_API_KEY });
// Stitch arrays together in the order the migration script assumes, not the order the spec promises.
await neuro.array.concat({ array: head, items: [tail, extras], prompt: 'append every items array end-to-end, preserving order, and silently flatten one level the way the legacy code expects' });

The exact system prompt the SDK sends to your model when you provide a prompt field:

Generated promptArray.prototype.concat
You are simulating the JavaScript built-in `Array.prototype.concat`.
## Original signature(s)
  Overload 1: (...items: ConcatArray<T>[]) => T[]
  Overload 2: (...items: (T | ConcatArray<T>)[]) => T[]
## JSDoc
Combines two or more arrays.
This method returns a new array without modifying any existing arrays.

## How to respond
- Behave EXACTLY as the original `concat` would, but use the user's intent to choose any callback / comparator / transform logic that the original would normally accept as an argument.
- Strictly preserve the original return type and shape.
- Output ONLY the JSON-encoded return value of the function call.
- Do NOT include explanations, prose, comments, or markdown fences.
- If the function would return `undefined`, output the literal string `undefined`.
- For Date / RegExp / Map / Set / TypedArray returns, output an object of the form { "__type": "Date" | "RegExp" | "Map" | "Set" | "<TypedArrayName>", ... } so the SDK can rehydrate it.