pub const MAGI_NOTE: &str = "magi: ";Expand description
Prefix on an agent turn that magi wrote rather than an agent.
A failed turn has to be visible, and the transcript is the only surface
the phone renders, so the failure goes in as an agent turn carrying this
marker. Two turn authors is what the wire shape allows (operator /
agent), and inventing a third would break every client written against
it; a stable prefix the UI can key on costs nothing and loses no
information.