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Polyglot 2.0 does not expose a markdown-JSON response mode. In previous versions, OutputMode::MdJson instructed the model to wrap its JSON response in a Markdown code block (```json ... ```), and Polyglot would extract the JSON content automatically. This was useful as a compatibility fallback for providers that lacked native JSON output support.

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Why It Was Removed

Polyglot 2.0 is designed to model only native provider request fields. Since markdown-wrapped JSON is a prompt-based convention rather than a native API feature, it does not belong in Polyglot’s abstraction layer. The response shape in Polyglot 2.0 is controlled entirely by standard request parameters:
  • responseFormat for JSON object and JSON schema modes
  • tools and toolChoice for tool calling
There is no responseFormat type for “respond with JSON inside a Markdown code block” because no provider API supports that natively.

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What to Use Instead

If you need prompt-based JSON fallback strategies — for example, when working with providers that do not support native JSON output — use the Instructor layer above Polyglot. Instructor handles response format negotiation, prompt engineering for structured output, and extraction of JSON from various response formats, including Markdown-wrapped JSON. For providers that do support native JSON output, use JSON object mode or JSON Schema mode directly through Polyglot’s responseFormat field.

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Migration from 1.x

If your application previously used OutputMode::MdJson, you have two migration paths:
  1. Switch to native JSON. If your provider supports it, use responseFormat: ['type' => 'json_object'] for the same structured output with better reliability.
  2. Use Instructor. If you need the Markdown JSON fallback for providers without native JSON support, move that logic to the Instructor layer, which provides automatic format negotiation and extraction.