@type t() :: %GEPA.LLM.Response{
  adapter: module() | nil,
  cost: map() | number() | nil,
  messages: [term()] | nil,
  metadata: map(),
  model: String.t() | nil,
  object: map() | nil,
  provider: atom() | nil,
  raw: term(),
  session_ref: term(),
  stop_reason: atom() | String.t() | nil,
  text: String.t() | nil,
  tool_calls: [term()],
  tool_results: [term()],
  usage: map() | nil
}