Automatic whole-staff CSS/viewBox scaling must be the LAST resort after re-breaking is attempted, not the DEFAULT and only fallback

When content does not fit its allotted width, the professional engraving order of operations is: (1) tighten spacing within engraving-minimum limits, (2) re-break into more/shorter systems, (3) as a genuinely last resort, reduce staff size. Reducing staff size as the ONLY fallback is backwards.

Ross, The Art of Music Engraving (explicit ordering: spacing adjustment, then re-pagination/re-breaking, then size reduction, reserved for fitting a fixed page count); Gould, Behind Bars (implicitly agrees — discusses re-breaking and spacing before any mention of staff-size reduction).

This rule can be decided from pitches, durations and voices — no layout required. A validator can check it before anything is drawn.