Step Grid

The sequencer grid: steps across, lanes down, a page at a time. Tap a cell to toggle it, drag across a row to paint a whole stroke on or off, drag up or down on a lit cell to ride its velocity — with velocity drawn as fill height and brightness both, gate as the fill's width, ghost cells for computed previews, beat-group tinting, page tabs past 16 steps, and a playhead column driven by the host's clock, never by a display timer. Read-only it becomes a mini piano-roll, which is how the arpeggiator draws its computed line through the same cells a sequencer edits.