Spec: ../F11-eyes-ahead.md · Later phase; mocked now so renderer/generator carry the right metadata from day 1. Both mechanics, both stages. Notation engraved by embedded VexFlow.
disappearing measures lookahead 1 → 2 bars
READING · vanish · 1 bar · 2/3PerformanceFP-30X · USB
gone
♩ = 72 · bar 2
Lookahead 1. Read Ahead's core mechanic, MIDI-graded (a market first): each bar vanishes at the first onset played in it, so the hands work from the buffer while the eyes read the next bar. Bar 1 is gone; hesitations at bar boundaries are the signature diagnostic — they mark lookahead failure precisely.
READING · vanish · 2 bars · 3/3PerformanceFP-30X · USB
gonegone
♩ = 72 · bar 3
Lookahead 2. The vanish now trails the eyes by two bars — the buffer requirement doubles as skill grows. This is the professional eye-hand span (~4 notes) being trained directly.
memory flash memorize → play from memory
READING · memory flash · 2/3RehearsalFP-30X · USB
3s
memorize — 2 bars
Memorize stage — the staff then blanks and both bars are played from memory. F8's mechanic scaled to musical context, the purest eye-hand-span measure (candidate minor input to the 07 Reading rating). Needs per-bar bounding boxes from <StaffView>.
READING · memory flash · 3/3RehearsalFP-30X · USB
Play it — both bars
from memory…
9 of 10 notes · contour intact Good
Recall stage. Blank staff, play from the buffer. "Show me" reveals the score with the played take overlaid — the reveal is the teaching moment.