Line breaks were always placed by songtrace, midway between lines and
recomputed around edited ones, so a break could not be put where a singer
breathes. The sheet now draws the breaks either side of a line as markers
that drag along the beat grid, kept between the lines they separate, and
double-click back to automatic. Break moves share the line's undo history
and SAVE LINE, which saves the notes only if they changed, so moving a
break never locks either line's notes.
Moved breaks are stored in edits.json keyed by the line each comes before,
follow their lines when the lyrics change, and win over the computed break
on every rebuild, clamped so a break never lands inside a line's notes.
The review lists each break with that line and whether it was moved, and
PUT /api/jobs/{id}/breaks takes {line: seconds | null}. merge now passes
untouched notes through as they are rather than rebuilding them, which
added float noise to their durations.
branderson