chatlas 0.18.0

New features

• New StreamController class for cooperative stream cancellation. Pass a controller to .stream() or .stream_async() and call controller.cancel() to stop the stream cleanly (e.g., from a Shiny "stop generating" button). The partial response is preserved in conversation history. (#279)

Improvements

• ChatAnthropic() and ChatBedrockAnthropic() now use Anthropic's native structured outputs API for Claude 4.5+ models, enabling streaming with data_model. Older models fall back to the tool-based approach. A new structured_output_mode parameter ("auto", "native", or "tool") lets you override the auto-detection. (#263)
• When a stream is interrupted (closed early, cancelled, or errors), the accumulated content is now saved as a partial AssistantTurn so conversation state isn't lost. Partial turns display [interrupted] (or the cancellation reason) in the Chat repr and are excluded from token/cost accounting. (#279)
• ChatBedrockAnthropic() now defaults to cache="5m", enabling prompt caching by default — matching ChatAnthropic()'s behavior. (#308)
• ChatOpenAI() now warns when base_url points to a non-OpenAI host, guiding users to ChatOpenAICompletions() for third-party backends like vLLM, Ollama, and LiteLLM. (#285)

Bug fixes

• Fixed thinking content being silently dropped during streaming for completions-based providers (DeepSeek, Groq, OpenRouter, etc.). The streaming path was returning finalized ContentThinking objects instead of ContentThinkingDelta fragments, which the TurnAccumulator didn't recognize. (#301)
• Fixed model_dump(mode="json") failing on Turns containing bytes fields (e.g., ContentPDF.data, thought_signature in ContentToolRequest/ContentThinking extras). Bytes values are now base64-encoded during serialization and decoded on validation, so JSON round-trips work correctly.
• batch_chat(), batch_chat_text(), and batch_chat_structured() now correctly return None when wait=False and the job is still incomplete. Previously they returned [], making it impossible to distinguish "all requests failed" from "job not done yet". (#306)
• ChatDatabricks() (and other ChatOpenAICompletions() providers) no longer fail with HTTP 400 when the conversation history contains empty assistant content, which can occur during tool calling. (#305)