Third line of the home screen: 'ParVagues' at rest; 'REC mm:ss' while the
gig-log k:'rec' stream says audio is landing on disk (tail-read of the newest
gig jsonl, same style as last_eval); '?REC' when the files and OSC lenses
disagree — a timer the performer must not trust blindly is marked, not hidden.
Stale or absent signal degrades to the plain footer, never crashes a redraw.
Pure decision function rec_line() + tests.