@type cost() :: %{
  input: float(),
  output: float(),
  cache_read: float(),
  cache_write: float()
}

Per-token cost in USD per million tokens.

@type model_type() :: :llm | :rlcd

Whether a model is a chat/agent model (:llm) or an RLCD decision model (:rlcd) — see Planck.AI.evaluate/4. RLCD models don't support chat, streaming, or tool calling.

@type provider() :: :anthropic | :openai | :google | :typesafe

Supported LLM provider backends.

@type t(type) :: %Planck.AI.Model{
  api_key: String.t() | nil,
  base_url: String.t() | nil,
  context_window: pos_integer(),
  cost: cost(),
  default_opts: keyword(),
  has_api_key: boolean(),
  id: String.t(),
  identifier: String.t() | nil,
  input_types: [:text | :image | :image_url | :file | :video_url],
  max_tokens: pos_integer(),
  model: String.t() | nil,
  name: String.t(),
  provider: provider(),
  supports_thinking: boolean(),
  type: type
}

An LLM model struct.

• id — user-facing alias (e.g. "sonnet"); used to look up the model in config.
• model — actual API identifier sent to the provider (e.g. "claude-sonnet-4-6"); falls back to id when nil (legacy flat-config path).
• identifier — uppercase env-var prefix for custom OpenAI-compat providers (e.g. "NVIDIA" → resolves NVIDIA_API_KEY).
• has_api_key — when false, the adapter skips env-var lookup and sends "not-needed" as the API key (for local servers like llama.cpp).
• api_key — not used at runtime; reserved for future in-memory overrides.
• type — :llm (chat/agent model) or :rlcd (decision model, see model_type/0). Defaults to :llm.

t/1 is parameterized on type — e.g. Model.t(:llm) narrows to a model known (by whatever produced it, not by anything Dialyzer infers from nothing) to be a chat/agent model; t/0 is the unnarrowed t(model_type()). Use t(:llm)/t(:rlcd) as a return type on a function whose own logic guarantees the narrower type — e.g. one that inspects model.type at runtime and only returns on one branch — so Dialyzer's inferred success typing matches the declared @spec instead of flagging it as an invalid_contract.