Function remove_device_files 

pub fn remove_device_files(
    folder: &Path,
    key: &[u8; 32],
    memory: &Path,
    computer: &str,
    stores: &[Store],
    device: &str,
    now_ms: i64,
) -> Result<DeviceFiles, String>

“Remove its files” for a device that no longer counts here (it left, you forgot it, another replaces it: sealed facts and your own word only; a live one is forgotten first, by the window): every round of its records (its last full round too), its entry, its claims, its texts to send, its note of how far it read once it left or was replaced, and its notes’ and papers’ sealed files that no record known here names, taken out of the folder here and of what was fetched beside it; the sending takes them out of the server (remote::Departed), and none is fetched again. Each device keeps what it already read; a device joining later never gets its records unless another device’s records carry them (texts restored on a new phone). A device that counts here is refused (“share-device-counts”).