Arpeggiator pad · gemma-4-26b-a4b-it

The user wants a pentatonic synthesizer pad grid and arpeggiator using `tone.min.js`.

Key requirements:
Two octaves of C-major pentatonic scale (C, D, E, G, A).
10 pads (5 notes * 2 octaves).
Clicking a pad plays the note, provides visual feedback, and toggles its selection in the arpeggiator.
A synthesized voice with reverb.
Play, Stop, Tempo control (60-180 BPM).
Plays selected notes in ascending pitch order, one eighth-note step.
User gesture to start audio.
One `index.html` file, all CSS/JS inline. Use `tone.min.js` via `<script src="tone.min.js"></script>`.

Plan:
1. Check if `tone.min.js` is present.
2. Create `index.html`.
3. Implement the UI (grid of pads, controls).
4. Implement the audio logic (Tone.js: Synth, Reverb, Transport/Sequence).
5. Implement the arpeggiator logic (iterating through selected notes).
6. Implement visual feedback.
7. Verify.

Let's start by checking the environment.

`tone.min.js` is present.

I will now create `index.html`.

Plan for `index.html`:
- HTML structure:
    - Controls: Play/Stop buttons, Tempo slider.
    - Grid: 10 pads. Each pad contains:
        - Label (e.g., "C3").
        - Toggle button (to select/deselect for arpeggiation).
        - Visual indicator (the pad itself).
- CSS:
    - Flexbox/Grid for layout.
    - Styling for pads (active, selected, inactive).
    - Responsive design (though not strictly required, good practice).
- JS:
    - Tone.js setup: `Tone.Synth`, `Tone.Reverb`, `Tone.MasterVolume`.
    - State: `selectedNotes` (Set of note names), `tempo` (BPM), `isPlaying` (boolean).
    - Note names for C-major pentatonic: C3, D3, E3, G3, A3, C4, D4, E4, G4, A4.
    - Event listeners:
        - Pad click -> Play sound + toggle selection.
        - Play/Stop buttons -> Toggle `Tone.Transport`.
        - Tempo slider -> `Tone.Transport.bpm.value`.
    - Arpeggiator:
        - `Tone.Sequence` or `Tone.loop`?
        - Since we want to iterate through selected notes in ascending order, a `Tone.Loop` or `Tone.Sequence` on the Transport is better.
        - `Tone.Sequence` is usually for fixed patterns. A `Tone.Loop` that plays the next selected note every 8th note is more flexible for dynamic selections.
        - Actually, `Tone.Sequence` is fine if we update it or just use a `Tone.Loop` with a logic that finds the next selected note.
        - Let's use `Tone.Loop` running on the `Transport`.

Let's refine the notes:
C3, D3, E3, G3, A3 (5 notes)
C4, D4, E4, G4, A4 (5 notes)
Total 10.

Wait, the requirement says: "Provide a separate sequence-selection toggle for each pad. Start with a nonempty selection. The arpeggiator repeatedly plays selected notes in ascending pitch order, one note per eighth-note step."

Implementation details:
- `Tone.Synth` with `Tone.Reverb`.
- `Tone.Transport.bpm.value = tempo`.
- `Tone.Transport.start()` and `Tone.Transport.stop()`.
- `Tone.Loop` at 8th notes.
- State: `selectedNotes` (Set of note indices or note names).
- `currentNoteIndex` for the arpeggiator.

Wait, if I use `Tone.Loop`, I need to make sure that when I stop, it doesn't create overlapping schedulers.
I should use `Tone.Transport.stop()` and `Tone.Transport.start()`.

Let's write the code.

I have created the `index.html` file. Now I need to test it.
The requirements are:
- Show ten labeled pads for two octaves of a C-major pentatonic scale.
- Clicking a pad plays its note and visibly marks the active pad.
- Provide a separate sequence-selection toggle for each pad.
- Start with a nonempty selection.
- The arpeggiator repeatedly plays selected notes in ascending pitch order, one note per eighth-note step.
- Play, Stop, and tempo control (60-180 BPM).
- Activate audio through a user gesture.
- Stop prevents new arpeggiator notes.
- Synthesize every sound.

I'll use the `browser` tool to inspect the application.
First, I need to make sure the file is actually running and visible. I'll use the `browser` tool to open it.
Wait, I can't "open" it directly like a browser, but I can use `browser` which is designed for this.
Actually, I should just run it. The `browser` tool is for inspecting the output.
I'll use `browser` to check the functionality.
Wait, I'll first try to run it.