> ## Documentation Index
> Fetch the complete documentation index at: https://docs.instructorphp.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Upgrade

Polyglot 2.0 is centered around explicit request fields.

The main migration points are:

* remove old output mode usage
* set `responseFormat` for native JSON or JSON schema
* set `tools` and `toolChoice` for tool calling
* use `stream()->deltas()` for streaming

## Response Model

Polyglot is now explicitly the raw inference layer.

* `InferenceResponse` is the final raw provider response
* streaming yields `PartialInferenceDelta`
* structured value ownership belongs to higher-level packages such as Instructor

If older code assumed that Polyglot streaming yielded accumulated partial response snapshots, update that code to work from deltas instead.

## Before

```php theme={null}
<?php

$data = $inference
    ->with(
        messages: 'Return JSON.',
        mode: $oldMode,
    )
    ->asJsonData();
// @doctest id="8c57"
```

## After

```php theme={null}
<?php

use Cognesy\Messages\Messages;
use Cognesy\Polyglot\Inference\Data\ResponseFormat;
use Cognesy\Polyglot\Inference\Inference;

$data = Inference::using('openai')
    ->withMessages(Messages::fromString('Return JSON.'))
    ->withResponseFormat(new ResponseFormat(type: 'json_object'))
    ->asJsonData();
// @doctest id="3a6a"
```

Markdown-JSON fallback is no longer a Polyglot concern.
Use Instructor when you need higher-level structured output strategies.

## Streaming Migration

Update old streaming code like this:

* replace partial-response iteration with `stream()->deltas()`
* assemble final raw output with `final()`
* move partial structured parsing to Instructor or your own delta accumulator