Function bring_media 

fn bring_media(
    text: &mut Text,
    vault: &(PathBuf, [u8; 32]),
    budget: &mut u64,
) -> bool

Each part of a message that travels, copied from Android into the private folder, hashed, put in the sharing as a sealed blob (never inside a line), the copy deleted; within budget bytes, the first part of a step always. Whether every part was brought (else the message waits for the next step).