I thought of what Hexano would evolve to so made a new prompt:
Create a single-file HTML application titled "Rolidy" that functions as a multi-instrument piano roll sequencer using the Web Audio API.
Layout & Styling:
The page should have a dark toolbar at the top and a scrollable main container taking up the rest of the viewport.
The main container (#pianoRollContainer) must hold an inner wrapper containing a label column and a canvas.
The Label Column (#labelsCol): Must be position: sticky and left: 0 so it stays fixed on the left side during horizontal scrolling. It should display pitch names (C1 to B7).
The Canvas (#rollCanvas): Should be large enough to hold a grid of 64 beats * 4 subdivisions (256 steps total) and 84 pitches (7 octaves).
Cell dimensions: 40px wide by 20px high.
Multi-Instrument Logic (Crucial):
There are 4 separate instruments, distinguished by color: Red, Blue, Green, and Yellow.
Interaction: Each grid cell on the canvas is subdivided into 4 quadrants (top-left, top-right, bottom-left, bottom-right). Clicking a specific quadrant toggles the note for the corresponding instrument at that step and pitch.
Data Structure: Use an array of Uint8Array to store the grid state, utilizing bitwise operations (bitmasking) to store the active state of the 4 instruments for every step/pitch.
The melody stops after the last note stops playing, meaning that a single note will only play one note, this is reset on Loop.
Toolbar Controls:
4 Dropdowns: Label them with colored squares (Red, Blue, Green, Yellow) to select the oscillator waveform (sine, square, sawtooth, triangle) for each instrument.
Checkboxes: "Hold" (to sustain consecutive notes) and "Loop" (to loop playback).
Buttons: Play (green), Stop (yellow), Export (blue), Clear (red).
Interaction Features:
Drawing: Left-click toggles notes on the canvas.
Panning: Two-finger touch should pan/scroll the view.
Highlighting: Hovering over the canvas should highlight the active row and column with a semi-transparent blue overlay.
Keyboard: Pressing the Spacebar should toggle Play/Stop.
Audio & Playback:
Initialize an AudioContext on play.
Draw a vertical playhead line that moves across the grid during playback.
Implement "Hold" mode: If active, consecutive notes for the same instrument should be scheduled as one long sustained note rather than rapid re-triggering.
Implement "Loop" mode: The playback should restart from the beginning when it reaches the end.
Export Feature:
Implement an "Export" button that uses OfflineAudioContext to render the current sequence to a WAV buffer, converts it to a Blob, and triggers a download of the .wav file.
I will likely change things to make it work more like its predecessor with that glorious panel that allows for importing and exporting.