.Net: Support reasoning/thinking as first-class content in ChatMessage abstraction

[PrathamAditya]

Problem

Several LLM providers (e.g., Ollama, OpenAI reasoning models) return structured reasoning data (e.g., thinking, reasoning, or similar fields).

Currently, this information is not represented in the Microsoft.Extensions.AI / Semantic Kernel abstraction model and is therefore lost or requires workarounds.

---

Current Limitation

• ChatMessage only supports:

  • Contents (text, image, function calls, etc.)

• There is no standardized way to represent:

  • reasoning / thinking
  • intermediate model traces

As a result:

• Providers like Ollama expose reasoning via RawRepresentation
• Consumers must rely on provider-specific parsing

---

Impact

• Loss of useful model output (reasoning/debugging)
• Inconsistent behavior across providers
• Harder to build advanced tooling (debugging, tracing, explainability)

---

Proposed Directions

Possible approaches:

Option 1: New Content Type

Introduce a new content type:

ReasoningContent : AIContent

Option 2: Metadata-based

Expose reasoning via standardized metadata:

content.Metadata["reasoning"]

Option 3: Extended ChatMessage

Add optional structured fields for reasoning

---

Context

A recent fix for Ollama required extracting reasoning from RawRepresentation, which works but highlights this abstraction gap.

---

Goal

Provide a consistent, provider-agnostic way to expose reasoning/thinking content across all supported LLM providers.

---

Happy to contribute to design/discussion if helpful.