LLM 0.32a0 alpha refactors Python library to handle diverse input and output types via messages and typed streaming parts

Simon Willison released LLM 0.32a0 on 29th April 2026, an alpha version of his LLM Python library and CLI tool. The release introduces two key changes: model inputs can now be represented as a sequence of messages (matching the conversational turn format used by major vendor APIs), and model responses can be composed of a stream of differently typed parts rather than plain text.

Previously, LLM modeled prompts and responses as simple text-in/text-out. The new interface supports feeding in previous conversations at the start using `model.prompt(messages=[user(...), assistant(...), ...])`, and responses can now stream mixed content types—reasoning output, text, JSON tool calls, tool outputs, and other formats—allowing the library to represent capabilities like OpenAI's code interpreter or Anthropic's web search.

The CLI tool can now display "thinking" text in a different color from final response text, with thinking text sent to stderr so it does not affect piped results. The prior `prompt=` option still works but is upgraded to a single-item messages array behind the scenes.