cube-js/cube ? reverse-engineered prompt

Build me a local open source semantic layer for analytics that I can point at my data warehouse and use to define metrics, dimensions, joins, and access rules in one place.

I want to be able to connect it to common SQL data sources like Postgres and cloud warehouses, then query the model through SQL, REST, and GraphQL so I can use it with BI tools, custom apps, or AI agents. It should feel headless, so no UI is needed beyond whatever basic setup or playground is necessary to get started.

Please make it easy to run locally with Docker, with clear setup instructions and sensible defaults for development. If you need to check the latest docs online while building, do that. Also make sure the model supports caching so queries stay fast and can handle lots of requests without falling over.