New release of LLM adds support for reasoning traces, OpenAI Responses, server-side tools, and smarter logging

Simon Willison: The bigger challenge with that kind of API concerns logging. If we're going to support the pattern where the message sequence is appended to on every request, ideally we can avoid logging all of that duplicate JSON for every turn. The solution is the new content-addressable message store, modeled after Git. You can see the new schema for that in the documentation, but the llm logs and llm logs --json commands have both been upgraded to convert that format back into something that's easy to consume.

Simon Willison: Quite a few of the lower-level tools changes in this release were driven by the needs of Datasette Agent. When I started work on LLM, the term "agent" had such a vague definition that I refused to use it. In September 2025 I came around to the idea that "An LLM agent runs tools in a loop to achieve a goal" is well established enough now that I could stop avoiding the term entirely. Tool chains can now pause for human approval and resume from a stored message history - both needed by Datasette Agent. Looking at LLM today it's beginning to look very agent-shaped to me. There's something neat about having a CLI utility that can mix and match different tools from different sources with different models all as a one-liner, and that includes a Python library powerful enough to build systems like Datasette Agent and llm-coding-agent. Maybe the next version of LLM will bake the concept of an "agent" into the core library. I'm still trying to figure out what that would look like.

Simon Willison: LLM's Python API previously required you to create a conversation and then send messages to it one at a time. This was an abstraction over the true nature of LLMs, where each request carries a complete history of the messages that came before it. That abstraction started to get in the way for some more advanced cases, so the new release introduces a model.prompt(messages=[]) parameter... LLM previously returned an iterable sequence of strings from each prompt. This worked great when models returned a string response, but failed to predict the weird shape that models would evolve towards. Today many models return a mix of reasoning text, output strings, tool calls, and even image attachments. With LLM 0.32 you can do this instead: for event in model.prompt("Explain cats").stream_events(): if event.type == "reasoning": print(f"[thinking] {event.chunk}", end="", flush=True) elif event.type == "text": print(event.chunk, end="", flush=True) else: print(f"Other event: {event}")