What stays
Campaign data, transcripts, characters, world state, dice and their seeds, in one SQLite file in your application data directory. The engine binds to loopback only, so it is not reachable from your network. A cloned voice is recorded on your machine and never uploaded, and deleting a campaign deletes its synthesised speech from the cache.
What leaves
Only what you configure, and only to where you point it. A local model: nothing. Your own key: directly from your machine to that provider, under their terms, with no middle step. Your key lives in your operating system's secret store, never in a config file. One honest exception: bringing a rulebook can send pages of your own copy, once, to the model endpoint you configured, so the engine can propose its system. Switch that pass off and the book is read entirely on your machine. An ingested book is never redistributed either way.
Telemetry
None ships today and none is enabled by default. If it is ever added it will be opt-in and carry counts only: never transcript content, never character names, never anything you typed.