chibicco published a hands-on test of fm, the command macOS 27 includes for Apple's Foundation Model. The model runs on the Mac itself. No app to install, no API key. On an eligible machine, opening Terminal and typing fm chat starts a conversation. Apple's own naming is "on-device model" or "Apple Foundation Model", and he is careful that fm is the command line tool that calls it, not the model.
First run trips a legal notice. fm available reports that the CLI license has not been agreed, and the acceptance applies to every user on the machine, so it must be run once as a privileged user: sudo fm license. That is the only sudo in the workflow.
The usage surface is small. fm respond takes a question and prints the answer in the terminal. fm chat keeps a session going with context. --image accepts a screenshot, which surprised him; he had expected a text-only model. fm schema builds a JSON output shape, and fm respond --schema returns that structure; his example fed a screenshot showing Messages, Mail, and Calendar and got back {"app_names":["Messages","Mail","Calendar"]}. fm serve exposes the model as a local API, which he notes will be the familiar shape for anyone who has run Ollama.
What is actually running? A one-line Swift script against the Foundation Models framework printed the variant and the context size: AFM 3 Core Advanced, 8,192 tokens. Apple's support page puts the Mac guideline for AFM Core Advanced at M3 or later with 12GB of unified memory, though he recommends checking the real machine rather than trusting the docs.
The context window is the real limit. The 8,192 tokens cover the question, the conversation history, and the answers together, not just input. Short questions, summaries of a few hundred to a few thousand characters, small code snippets, a few turns of chat all fit. Meeting transcripts, large design documents, and whole repositories do not.
He probes it twice. Asked why the Roman Empire used smartphones, it flagged the false premise. Asked for the plot of a novel that does not exist, Natsume Soseki's "Monday Penguin", it invented one, dated to 1916, with a penguin that wanders into a human household and becomes part of the family. He calls the result adequate for a current local model, with room to improve.
He verified everything on 17 Sep 2026 and notes that features can change with macOS or model updates. One of the support pages he cites for the hardware guideline is titled "How to get Siri AI".