It means the development loop runs on your machine. Emolysis pulls a small sample of your data into DuckDB, fills templates, and runs golden tests locally, so iterating does not spend warehouse compute. Production still runs on your platform, under your account.
It does not mean that nothing leaves your machine. To write code, the agent sends prompts to the AI model provider you choose, and a prompt can include table and column names, schemas and sample values. With a paid plan's model usage, those prompts pass through Emolysis's metering service, which is designed not to store or log their content. Dashboards leave your machine when you publish them, and only then.
The full list is on the security page, under "What leaves your machine", and in the data handling docs. Our post why local-first data engineering explains the idea in more detail.