defmodule LLM.Stream.Thinking do
  @moduledoc """
  A thinking/reasoning chunk from a streaming response.

  Emitted by providers that support extended thinking (Anthropic, Gemini, OpenAI o-series).
  Thinking chunks contain the model's internal reasoning process, separate from the
  final response text.

  ## Fields

  - `:text` — the reasoning text fragment
  - `:signature` — optional cryptographic signature (Anthropic) for thinking block verification

  ## Example

      %LLM.Stream.Thinking{text: "Let me consider the user's question...", signature: nil}

      # Anthropic includes a signature for verification
      %LLM.Stream.Thinking{
        text: "The user is asking about...",
        signature: "EqQBCgIYAhIM..."
      }
  """

  @type t :: %__MODULE__{
          text: String.t(),
          signature: String.t() | nil
        }

  defstruct [:text, :signature]
end