# `LlmComposer.StreamChunk`
[🔗](https://github.com/doofinder/llm_composer/blob/master/lib/llm_composer/stream_chunk.ex#L1)

Normalized representation of a streaming chunk emitted by any provider.

- `:provider` identifies the upstream provider (:open_ai | :open_router | :google | :ollama | :bedrock)
- `:type` categorizes the event (`:text_delta`, `:reasoning_delta`, `:tool_call_delta`, `:usage`, `:done`, `:error`, `:unknown`)
- `:text` is the accumulated text delta (if any)
- `:reasoning` is the accumulated reasoning delta (if any)
- `:reasoning_details` keeps structured reasoning detail fragments when providers emit them
- `:tool_calls` keeps normalized tool/function call fragments
- `:usage` stores the token usage payload when available
- `:cost_info` can surface cost data on the final chunk
- `:metadata` holds provider-specific attributes (finish reason, role, etc.)
- `:raw` retains the original decoded payload for inspection.

# `t`

```elixir
@type t() :: %LlmComposer.StreamChunk{
  cost_info: LlmComposer.CostInfo.t() | nil,
  metadata: map(),
  provider: atom(),
  raw: term(),
  reasoning: String.t() | nil,
  reasoning_details: list() | nil,
  text: String.t() | nil,
  tool_calls: [LlmComposer.FunctionCall.t() | map()] | nil,
  type:
    :text_delta
    | :reasoning_delta
    | :tool_call_delta
    | :usage
    | :done
    | :error
    | :unknown,
  usage: usage() | nil
}
```

# `usage`

```elixir
@type usage() :: %{
  input_tokens: non_neg_integer() | nil,
  output_tokens: non_neg_integer() | nil,
  total_tokens: non_neg_integer() | nil,
  cached_tokens: non_neg_integer() | nil,
  reasoning_tokens: non_neg_integer() | nil
}
```

---

*Consult [api-reference.md](api-reference.md) for complete listing*