Piano synth · gemma-4-26b-a4b-it

The user wants me to build a playable piano keyboard using `tone.min.js`.
The application must be a single-page web app in `index.html` with inline CSS and JS.
No external resources/CDNs.
Use the provided `tone.min.js` via a script tag.

Requirements:
- Chromatic octave C4 to C5 (C4, C#4, D4, D#4, E4, F4, F#4, G4, G#4, A4, A#4, B4, C5).
- Keys: A W S E D F T G Y H U J K.
- Mouse/Touch: Click/Press starts note, release stops note.
- Keyboard: Pressing/releasing keys starts/stops notes. Prevent auto-repeat.
- Voice: Synthesized (Tone.js), ADSR envelope.
- Concurrency: At least 3 simultaneous notes.
- UI: Highlight keys while held.
- Safety: Release held voices when pointer is released outside or window loses focus.
- UI: Display computer-key mapping.
- Audio Activation: User gesture required.

Plan:
1.  Check if `tone.min.js` is present.
2.  Create `index.html` with the required structure.
3.  Implement the Piano UI (HTML/CSS).
4.  Implement the Piano Logic (JS/Tone.js).
5.  Verify functionality.

Step 1: Check for `tone.min.js`.

Okay, `tone.min.js` is present.

Step 2: Design the HTML/CSS/JS structure.

HTML:
- Container for the piano.
- A way to display the key mappings.
- Audio start button (to comply with browser audio policy).

CSS:
- Flexbox/Grid for the piano keys.
- White keys and black keys (overlapping/absolute positioning).
- Highlighting states.
- Labels.

JS:
- `Tone.Synth` or `Tone.PolySynth`. Since we need multiple notes, `Tone.PolySynth` is better.
- Key mapping:
  - A -> C4
  - W -> C#4
  - S -> D4
  - E -> D#4
  - D -> E4
  - F -> F4
  - T -> F#4
  - G -> G4
  - Y -> G#4
  - H -> A4
  - U -> A#4
  - J -> B4
  - K -> C5
Wait, let me re-read the mapping:
"A W S E D F T G Y H U J K in order to those 13 notes."
Wait, 13 notes:
1. C4
2. C#4
3. D4
4. D#4
5. E4
6. F4
7. F#4
8. G4
9. G#4
10. A4
11. A#4
12. B4
13. C5

Let's map them:
A -> C4
W -> C#4
S -> D4
E -> D#4
D -> E4
F -> F4
T -> F#4
G -> G4
Y -> G#4
H -> A4
U -> A#4
J -> B4
K -> C5

Wait, the requirement says: "A W S E D F T G Y H U J K in order to those 13 notes."
Let's count them:
A(1) W(2) S(3) E(4) D(5) F(6) T(7) G(8) Y(9) H(10) U(11) J(12) K(13).
Total 13 keys.
The chromatic octave from C4 to C5:
C4, C#4, D4, D#4, E4, F4, F#4, G4, G#4, A4, A#4, B4, C5.
Total 13 notes.

Wait, let me re-check the mapping for standard piano layout.
Usually:
C4, D4, E4, F4, G4, A4, B4 are white keys.
C#4, D#4, F#4, G#4, A#4 are black keys.
Total 12 notes in an octave.
C4 to C5 is 13 notes (C4 to B4 is 12, plus C5 makes 13).

Mapping:
A -> C4
W -> C#4
S -> D4
E -> D#4
D -> E4
F -> F4
T -> F#4
G -> G4
Y -> G#4
H -> A4
U -> A#4
J -> B4
K -> C5

Wait, let's check the keys again.
A - W - S - E - D - F - T - G - Y - H - U - J - K
If A is C4, then W is C#4, S is D4...
Wait, E is D#4?
Let's look at standard keyboard layouts.
A-S-D-F-G-H-J-K is usually white keys.
W-E-T-Y-U is usually black keys.
Let's look at the prompt's requested mapping again: "A W S E D F T G Y H U J K in order to those 13 notes".
This is a bit unusual.
A (C4)
W (C#4)
S (D4)
E (D#4)
D (E4)
F (F4)
T (F#4)
G (G4)
Y (G#4)
H (A4)
U (A#4)
J (B4)
K (C5)

Okay, I will follow this exactly.

Implementation details:
- `PolySynth` with ADSR.
- `keydown` and `keyup` handlers.
- Use a `Map` to keep track of active notes to prevent auto-repeat issues.
- UI: A wrapper for the piano, and keys.
- Key mapping UI: A small table or list.

Let's write the code.

The code has a small syntax error in the `map-item` creation: `mapItem.className = ''map-item';` (double single quotes). I need to fix that.

Also, I should double check the piano key layout.
The way I'm appending black keys might be problematic if I just append them in order.
Standard piano:
White keys are siblings.
Black keys are positioned between certain white keys.
Wait, my implementation appends them in order.
C4, C#4, D4, D#4, E4, F4, F#4, G4, G#4, A4, A#4, B4, C5.
If I just append them, they will all be next to each other.
I need to use absolute positioning for black keys or a specific container structure.

Let's refine the HTML structure.
White keys should be in one container.
Black keys should be in a separate container with absolute positioning, or I can use a different layout.

Actually, a common way to do this with CSS:
The piano container is a relative container.
White keys are inline-block or flex.
Black keys are positioned absolutely.

Let's redo the `index.html`.

Wait, let's look at the `NOTES` array.
C4, C#4, D4, D#4, E4, F4, F#4, G4, G#4, A4, A#4, B4, C5.
If I append them in order:
- C4 (white)
- C#4 (black)
- D4 (white)
-...

If I want them to look like a piano, the black keys should sit between the white keys.
The white keys: C4, D4, E4, F4, G4, A4, B4, C5.
The black keys: C#4, D#4, F#4, G#4, A#4.

Let's structure the piano:
```html
<div class="piano-container">
  <div class="white-key" data-note="C4"></div>
  <div class="black-key" data-note="C#4"></div>
  <div class="white-key" data-note="D4"></div>
  <div class="black-key" data-note="D#4"></div>
  <div class="white-key" data-note="E4"></div>
  <div class="white-key" data-note="F4"></div>
  <div class="black-key" data-note="F#4"></div>
  <div class="white-key" data-note="G4"></div>
  <div class="black-key" data-note="G#4"></div>
  <div class="white-key" data-note="A4"></div>
  <div class="black-key" data-note="A#4"></div>
  <div class="white-key" data-note="B4"></div>
  <div class="white-key" data-note="C5"></div>
</div>
```

Wait, I need to ensure the order of events.
If I use the `NOTES` array, I should handle the rendering differently.
Actually, I can just hardcode the keys in the HTML to make it easier, or render them more carefully.

Let's re-examine the `NOTES` list.
C4, C#4, D4, D#4, E4, F4, F#4, G4, G#4, A4, A#4, B4, C5.
Total 13.
White: C4, D4, E4, F4, G4, A4, B4, C5.
Black: C#4, D#4, F#4, G#4, A#4.

Let's adjust the implementation.
I'll use a container for white keys and a container for black keys.
The black keys will be positioned relative to the white keys.

Or, better:
A container for the piano.
White keys as `display: flex`.
Black keys as `position: absolute`.

Let's rethink the layout.
White keys: `display: flex; width: 60px; height: 200px;`
Black keys: `position: absolute; width: 40px; height: 120px;`
We need to calculate the left position for black keys.

Wait, I can use a simpler approach.
I'll just create a single div and use `position: relative` for the piano.
The white keys will be in a flexbox.
The black keys will be placed at specific offsets.

Let's try this:
White keys: 7 keys (C4, D4, E4, F4, G4, A4, B4) + 1 key (C5). Total 8 white keys.
Wait, C4 to C5 is 8 white keys if we include both Cs.
C, D, E, F, G, A, B, C.
Black keys: C#, D#, F#, G#, A#.

Actually, let's just write the HTML/CSS carefully.

I need to fix the `mapItem.className = ''map-item';` error (double single quotes) which I missed in the previous attempt. I'll also check the piano layout logic.

Wait, my previous `write` command had a typo in the content: `mapItem.className = ''map-item';` (actually it was `mapItem.className = ''map-item';` in the text, which is not valid JS).

Let's fix the `index.html` content. I'll also improve the piano layout slightly to ensure it's perfect.
White keys:
- C4 (A)
- D4 (S)
- E4 (D)
- F4 (F)
- G4 (G)
- A4 (H)
- B4 (J)
- C5 (K)

Black keys:
- C#4 (W)
- D#4 (E)
- F#4 (T)
- G#4 (Y)
- A#4 (U)

I'll use `position: absolute` for black keys and `position: relative` for the piano container.
The white keys will be children of the piano container.

Let's refine the `index.html` one last time.
I'll use `write` to overwrite it.
I will also fix the `mapItem.className` error.
I'll also fix the `<span>` tags in the HTML. I used `</span` instead of `</span>`.

Looking at the previous `write` output:
`...<span>A</span><span>C4</span>...` (Wait, I wrote `</span` in my thought process but the `write` tool output shows `</span>` correctly).
Let me re-read the `write` output.
`...<span>A</span><span>C4</span>...`
Actually, it looks okay.

Wait, I see a potential issue:
`mapItem.className = ''map-item';` -> This will definitely cause a syntax error.

Let's try to run the application.

The user wants me to build a playable piano keyboard using `tone.min.js`.
The user has provided an initial image, which seems to be the output of a previous attempt (or a template) that I need to improve or implement from scratch based on the requirements.
Wait, looking at the prompt, it seems I am supposed to *build* it. The image might be from a previous run or a failed attempt by a different model/process, but I should just follow the instructions.

Requirements:
1.  **File**: `index.html` in the current directory.
2.  **Content**: Single-page web app (CSS in `<style>`, JS in `<script>`, inline).
3.  **Libraries**: Use `tone.min.js` via `<script src="tone.min.js"></script>`. No external CDNs.
4.  **Functionality**:
    -   One chromatic octave (C4 to C5).
    -   Correct black/white key layout with labels.
    -   Keyboard mapping: `A W S E D F T G Y H U J K` for 13 notes.
    -   Mouse/Touch support (Press to start, release to release).
    -   Synthesized voice with ADSR envelope.
    -   Support at least 3 simultaneous notes (polyphony).
    -   Highlight keys while held.
    -   Prevent keyboard auto-repeat issues.
    -   Release notes on mouse leave or window focus loss.
    -   Audio activation via user gesture (Start Audio button).
    -   Display key mapping.
    -   No audio files.

Plan:
1.  Check if `tone.min.js` exists in the current directory.
2.  Create `index.html` with:
    -   HTML structure: A container, a "Start Audio" button, a piano container with keys, and a legend for key mapping.
    -   CSS: Styling for the piano (white and black keys), highlighting, and layout.
    -   JS:
        -   Initialize `Tone.PolySynth` with an ADSR envelope.
        -   Handle "Start Audio" click.
        -   Map keys (A, W, S, E, D, F, T, G, Y, H, U, J, K) to notes (C4, C#4, D4, D#4, E4, F4, F#4, G4, G#4, A4, A#4, B4, C5).
        -   Keep track of active notes (to prevent duplicates and handle releases).
        -   Implement `keydown`, `keyup`, `mousedown`, `mouseup`, `mouseleave`, and `blur` events.
        -   Handle key presses and releases.

Let's start by checking the directory.