We need to create index.html with piano keyboard, supporting mouse and keyboard, use Tone.js's synth and envelope. Each key press triggers a note. Provide visual feedback (e.g., highlight key). We'll use a simple synth: Tone.Synth with attack, decay, sustain, release. Use voices: we can create polyphonic via .triggerAttack.

We need to load tone.min.js via <script src="tone.min.js"></script>. Then code inside script tag to create keys, event listeners.

We'll need keyboard mapping: mapping PC keys to piano notes: e.g., from 'A' to 'K' for white keys? Standard mapping: maybe:

C4: 'A'
D4: 'S'
E4: 'D'
F4: 'F'
G4: 'G'
A4: 'H'
B4: 'J'

Also black keys: C#4: 'W'; D#4: 'E'; F#4: 'T'; G#4: 'Y'; A#4: 'U'.

Alternatively, we can use a more complete set spanning 2 octaves.

Also visual keys: create div elements positioned horizontally: use CSS grid or flex.

Outline:

- HTML: <div id="piano"></div>.

- CSS: style white keys: width 40px height 160px; display inline-block; border etc. Black keys: width 25px height 100px; position: absolute over white keys.

- Provide JS:

-- Create an array of notes for 1 octave: ['C4','C#4','D4','D#4','E4','F4','F#4','G4','G#4','A4','A#4','B4'].

-- For each note, create key element with data-note attribute, class 'key white' or 'key black'.

-- For mapping to keyboard: create a mapping object mapping key codes or key values to note strings. Use e.g., 'a'->'C4', 'w'->'C#4', 's'->'D4', etc.

-- Track active keys: for keyboard, on keydown, if key not already active, play note; on keyup, release note.

-- For mouse, on mousedown on key, play; on mouseup or mouseleave, release.

-- Use Tone.Synth({envelope:{attack:0.01, decay:0.3, sustain:0.7, release:1}}).connect(Tone.Destination);

-- For polyphonic, we could use a buffer of multiple instances; but synth can handle polyphonic. simplified: synth.triggerAttack and triggerRelease.

Actually Tone.Synth is polyphonic by default? It probably can play multiple notes simultaneously. Confirm: Tone.Synth uses PolySynth? Might be better to use Tone.PolySynth. But keep simple: Tone.Synth can handle, but we can also use PolySynth.

We'll create synth = new Tone.PolySynth().toDestination(); Or use Tone.Synth. We'll use PolySynth.

Implement keyDown: synth.triggerAttack(note). keyUp: synth.triggerRelease(note). We'll maintain activeNotes set to avoid retrigger when key held.

Also highlight: add CSS class 'active' to key when triggered.

Add event listener to document for keydown, keyup. Use .toLowerCase() for keys.

Implement mousedown and mouseup on each key.

Also consider: key repeat. For keydown, use event.repeat to ignore repeats. For keyup, also.

Important: For mouse, we need to handle mousedown, mouseup, mouseleave to release.

We'll need to use Tone.start() on first user interaction to unlock audio context? Use tone.min.js: requires user interaction to start. So on first click or keydown, call Tone.start().

We'll produce final answer: code with index.html file.

Let's write the code. We'll use pretty CSS. Ensure it's one file.

We'll call with write function.

We need to ensure key placement of black keys relative to white keys; current code places black keys absolute but no offset to align to correct position. We want correct layout. Also use ADSR envelope. Tone.PolySynth default? Use Tone.Synth with ADSR envelope. We should create a gain envelope or use Synth('sine', {envelope: ...}). Tone.PolySynth can accept a constructor with adsr. Provide envelope param. And use set ADSR. Also implement key feedback with active classes. Also synth maybe use Tone.Volume? For now okay.

Better: use Tone.Synth with ADSR envelope. Let's create polySynth = new Tone.PolySynth(Tone.Synth, {envelope: {attack:0.02, decay:0.1, sustain:0.7, release:0.5}}).toDestination()

Also visual keys: highlight on active.

Also arrangement: We should include a container relative to put blacks at correct positions. Currently using negative margin left -1px for whites, black has margin-left -20px relative to its parent. That might not align.

Simpler: Use CSS grid with 7 columns per octave. Complicate.

But requirement: playable keyboard with visual key feedback, no external resources.

Simpler: Create container with relative, white keys as inline-block, black keys as absolutely positioned relative to white keys.

We need to place black keys at positions: between C-D (#), D-E (#), F-G (#), G-A (#), A-B (#). We'll map index positions.

We can build each white key with data-index and then create black keys accordingly.

Let's produce simpler: generate 7 white keys per octave. For single octave.

Implement:

Notes array with pattern: ['C4','C#4','D4','D#4','E4','F4','F#4','G4','G#4','A4','A#4','B4']. Use whiteIndices = [0,2,4,5,7,9,11]; blackIndices follow.

Compute positions by adding left offset after each white key. For each white key, set style left: index * width.

Black keys: left: (index of preceding white) * width + (width*0.75?) Actually black key width 40, relative to white 60, offset to center of space: 60 - 20 = 40? Actually black key sits midpoint over space between two white keys. The left offset for black key relative to parent container: (indexOf preceding white * 60) + 40? Let's calculate: first white C at left:0. Then black C# should be at left: 60 - 20 = 40? Because from left of C, 60 width, black width 40, we need left: 20? Wait we need black overlapped half over C and half over D. Usually black key starts at 60 - 20 = 40? Actually if C width 60, black should start at 60 - (black width/2) = 60 -20 = 40. Yes.

Thus algorithm: For each black note at index i in notes array, find preceding white key index j (where j = index of white note just before it). Then left offset: j * whiteWidth + (whiteWidth - blackWidth/2). Where whiteWidth=60, blackWidth=40.

Simplify: We'll create container position:relative. Set each white key inline-block 60x220. For black keys, we create absolute positioned elements relative to container. Use computed left positions.

Let's code accordingly.

Also we need ensure multiple events: mouse down/up across keys: we need for black and white key listeners.

Also need to support multiple notes simultaneously (PolySynth). Css active class.

Let's modify file.

We'll read the file written to update.

We added default synth. But requirement: ADSR envelope. Use Tone.Adsr? likely need to create synth with envelope.

Let's read tone.min.js? but not necessary.

We can modify for ADSR: Use Tone.AMSynth? We can use Tone.Synth with envelope property.

Audio synth: const synth = new Tone.Synth({
  oscillator: { type: "sine" },
  envelope: { attack: 0.01, decay: 0.2, sustain: 0.5, release: 1 }
}).toDestination();

But also want PolySynth to play multiple notes. Use PolySynth with that synth.

const synth = new Tone.PolySynth(Tone.Synth, {
  oscillator: { type:"sine" },
  envelope: { attack:0.01, decay:0.2, sustain:0.5, release:1 }
}).toDestination();

Alright.

Also we need controlling with mouse and computer keys; we already do.

Visual key feedback: we added active class.

But missing some black key positioning resets: The CSS for black keys margin-left negative relative to the preceding white key.

But we didn't adjust order: The layout isn't correct because we didn't create proper structure. Better create with container for white keys and overlay black keys.

Simpler: Using CSS to position black keys absolute left relative to container.

Better: build white keys then black.

Will adjust.

Create container with relative position. In loop, create white keys. For each note, create key; if black, create after with position absolute.

But we need correct.

Simpler: Use array of objects: track if it's black and a get position index.

I'll modify.

Let's rewrite building keyboard:

const keyPositions = []; We'll compute positions: index 0 white C4, # etc. easier to just build manually: For each white key at index wIndex. For each black key compute left offset.

Simpler: Build all white keys first: notes array ignoring sharps.

let whiteNotes = ['C4','D4','E4','F4','G4','A4','B4'];

For each create element.

Also keep map note-> element.

After all white, for each sharp note create black key positioned absolute: relative to preceding white key left: e.g., C#4 left offset 50%? But approximate.

Simpler: we can leave as previous design but need proper CSS. In earlier code we appended black after white but doesn't handle absolute positions. Let's adjust.

I'll modify building loop separately.

Also adjust CSS: .key.white { width: 60px; height:220px; } .key.black { width:40px;height:140px; etc; position:absolute; left: x; top:0. } Hmm need left percentages.

Could compute left offset based on index.

Using 7 white keys repeated pattern. Let's refer to typical piano layout: black keys are between: C# (between C and D), D# (between D and E), F# (between F and G), G# (between G and A), A# (between A and B). They skip between E-F and B-C.

Hence placement: For each pair of white keys, black key placed with left: (whiteIndex + 1) * 60px - 20 (half of black width minus etc). For simplicity we can approximate: For each black note, compute position relative to left of first white base.

Let's implement:

const whiteKeyWidth = 60;
const blackKeyOffset = 40; // width

We'll create container relative width: whiteKeyWidth*7=420. For each white key we create.

Use mapping.

Implementation detail: Use array of objects with note and type.

But easier: build all white.

After creation of all white, loop over blackNotes object mapping to preceding white index.

Better create mapping:

const blackMap = {
 'C#4':0,
 'D#4':1,
 'F#4':3,
 'G#4':4,
 'A#4':5
};

Place accordingly: left = (precedingIndex+1)*whiteKeyWidth - blackKeyWidth/2;

Because preceding white key's left offset equals precedingIndex*whiteKeyWidth.

Hence left = precedingIndex*whiteKeyWidth + whiteKeyWidth - blackKeyWidth/2.

Let's compute.

Also we need to adjust container width: 7*60=420.

Set piano width accordingly.

Let's implement.

Update code.

Also adjust event binding: we need to add 'mouseup' and 'mouseleave' only to key added; no cross.

Also adjust style .active classes for colored.

Let's patch index.html accordingly.

It seems the edit is failing because oldText not found due to special characters? Let's open first few lines to confirm.{"path":"index.html","line_start":1,"line_end":80}