Piano synth · minimax-m3

Let me start by exploring the current directory to understand what's available.

Good. I have `tone.min.js` available. Let me check the file briefly to understand what's available in the Tone object.

Let me plan out the implementation:

1. **HTML structure**: 
   - Title/header
   - Computer key mapping display
   - Piano keyboard with 13 keys (C4, C#4, D4, D#4, E4, F4, F#4, G4, G#4, A4, A#4, B4, C5)
   - 7 white keys and 5 black keys

2. **CSS**: 
   - Layout for white keys (flex with proper widths)
   - Black keys positioned absolutely
   - Highlight states for pressed keys
   - Aesthetic design

3. **JavaScript**:
   - Use Tone.js PolySynth with envelope
   - Map keys: A W S E D F T G Y H U J K → C4, C#4, D4, D#4, E4, F4, F#4, G4, G#4, A4, A#4, B4, C5
   - Track held notes to prevent duplicates
   - Handle keyboard events with `e.repeat` check
   - Handle mouse/pointer events
   - Release all notes when pointer leaves or window loses focus

Let me think about the 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

For the keyboard layout, the standard piano has black keys placed between certain white keys:
- C4 (white) | C#4 (black) | D4 (white) | D#4 (black) | E4 (white) | F4 (white) | F#4 (black) | G4 (white) | G#4 (black) | A4 (white) | A#4 (black) | B4 (white) | C5 (white)

So 7 white keys and 5 black keys. The black keys need to be positioned over the white keys.

I'll use Tone.PolySynth with Tone.Synth. For envelope ADSR:
- attack: 0.005 (quick attack)
- decay: 0.1
- sustain: 0.3
- release: 1.2 (longer release for natural decay)

For PolySynth, when I triggerAttack, I get a voice. When I triggerRelease, that specific voice releases. I need to track each note's voice to release it properly.

Actually, the simplest way is to track which notes are currently held by both computer key and mouse, and use triggerAttackRelease for short presses or triggerAttack/triggerRelease for held.

Let me design the implementation:

```js
const keyMap = {
  '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'
};
```

I'll have a Set to track held notes. When a note starts, add to set; when ending, remove from set and trigger release.

For preventing duplicates: when keydown event has e.repeat, ignore it (since the note is already held). On keyup, only release if the note was tracked.

For mouse: use pointerdown/pointerup. Track the active note in a variable. If pointer leaves the key (pointerleave, pointerout), release.

For window blur: release all.

Let me write the code now.

For the synth, I want:
```js
const synth = new Tone.PolySynth(Tone.Synth, {
  envelope: {
    attack: 0.005,
    decay: 0.1,
    sustain: 0.3,
    release: 1.2
  }
}).toDestination();
```

Let me create the file now.

Good, standard Tone.js UMD build. Let me write the index.html file with the piano.

Now let me run the application in the browser to verify it works correctly.

The gate overlay is showing as expected, with the Enable Audio button. Tone.js loaded successfully (v14.8.49). The worker CSP warning is harmless. Let me click Enable Audio to dismiss the gate, then check the piano layout.

The gate is still showing. The click might not have registered or the click was on the overlay backdrop. Let me check the actual coordinates - the button shows "Enable Audio" which appears around y=480. Let me click again more precisely on the button. Actually I clicked 600, 488 which should be on the button. The DOM still shows the gate is visible. Let me try clicking again with a different approach - maybe the click landed on the overlay backdrop. Let me look at the button coordinates more carefully. The image shows the button center at roughly x=600, y=488. Let me try clicking it again. Maybe there was an issue with the click not registering through the overlay.

Actually wait - the DOM still says "Click to enable sound" but the audio gate has class "gate" not "gate hidden". The CSS makes .gate.hidden display:none. Let me try the click again, perhaps with a longer pause.

The button is still there - my click didn't register. The button looks like it's around x=600, y=488. Let me try clicking directly on the button text area. Looking at the image, the "Enable Audio" button is at around (598, 488). Let me try once more with explicit positioning.

Actually maybe the click was sent but Tone.start() resolved and audioReady=true was set, then we hid the gate. But the DOM dump still shows the gate. Let me try clicking again with a slight offset, or use the inspect tool.

Wait, maybe the click is hitting a different element. Let me check the actual button position via inspect.

The gate is still showing. The screenshot might just be cached. Let me try clicking again. The button text "Enable Audio" is at approximately y=488 in the viewport. Let me try clicking with x=600, y=490. Actually, looking at the screenshot, the button is at the center of the image and around y=488. Let me try clicking it once more.

Wait, maybe the click IS happening but the audio activation is failing silently due to CSP? Let me check the console output - it doesn't show any errors after clicking. The console still shows the initial warnings but no error after the click. Let me try again with a precise click.

The clicks are still hitting the gate overlay but the gate is not being dismissed. Maybe the click is happening but the page is in a state where the gate doesn't disappear because of a CSP issue, or the click is being absorbed by the iframe sandbox.

Wait - looking at the console, the AudioContext warning is from the initial page load, not from the click. Let me try a different approach. Maybe I need to use the action differently. Let me try with a direct element selector.

Actually, looking more carefully, the issue might be that:
1. The click triggers Tone.start() which is async
2. Tone.start() might not be working in the sandboxed iframe
3. Or the click is not even reaching the button due to the overlay covering it

Let me try a different approach - I'll try sending the click with a slightly different x coordinate to make sure I hit the button text. Looking at the screenshot, "Enable Audio" text is centered at around x=599, y=488. 

Actually maybe the issue is that the click is processed but the Tone.start() Promise might have an error. Let me check by adding more logging, or just check if the click is even being received. Let me reload first to see fresh state.

Actually wait - I notice the screenshot always shows the same state with the gate visible. This could mean:
1. The click isn't reaching the button
2. The click is reaching but Tone.start() is hanging (which is possible in a sandboxed environment)
3. The button is being clicked but error is thrown

Let me try clicking using a slightly different x position. The button text might be at exact center. Let me try clicking and then immediately taking a screenshot to see.

Actually let me try this - if the click is happening but the button's click handler doesn't work for some reason, I can try using `pointerdown` directly. But first let me see if the page state changes. Let me first reload to get a clean state, then try clicking.

Hmm, but I've already tried. Let me look at the actual rendered output more carefully. The button text "Enable Audio" is shown. The click coordinates I used (599, 488) should be exactly on the button. 

Let me try clicking on a slightly different position - maybe (600, 490). Also, since the action returns immediately, perhaps the screenshot is just showing what was there before. Let me try a different approach - just check after multiple actions.

Actually I wonder if the issue is the click event isn't propagating through the overlay. Let me look at my CSS - the .gate has `position: fixed; inset: 0;` and `display: flex; align-items: center; justify-content: center;`. So the button should be clickable within. The button itself has no pointer-events: none.

Maybe the click action is sending a single click, but the Tone.start() might be rejecting because the gesture isn't being detected. Let me check.

Actually, you know what - maybe the issue is the action "click" works fine, but Tone.start() is throwing an error. Let me check the console output more carefully. The current console shows the original warnings but no errors after the click. The click action returns immediately though - it doesn't wait for the page to update.

Let me check after a small delay - take another screenshot.

I notice there's a new console warning about "blob:" worker being blocked by CSP. This is concerning - the Tone.js library uses web workers via blob: URLs but the CSP is blocking them. This might affect functionality.

Let me look at the situation more carefully. The click might be hitting the button but Tone.start() isn't completing because:
1. CSP blocks workers (the offline worker for offline context), but Tone.js should still work in online mode
2. Maybe the iframe sandbox has issues

Let me try clicking the button using a different approach - maybe press the keyboard 'Enter' after focusing the button, or just check what happens after click.

Actually, the audio playback in a sandboxed iframe with `allow-same-origin` may not actually produce sound, but the JS should still run. So `audioReady` should still get set to true and the gate should be hidden. Unless Tone.start() throws.

Let me investigate by clicking the button and checking the DOM right after. Maybe the issue is that my click is hitting the .gate overlay but not the button.

Wait - I bet the issue is the click is firing Tone.start() but Tone is logging the AudioContext warning again (which is in the initial console). Let me wait a moment then take a screenshot to see the current state.

The click keeps showing the gate. The click IS being delivered (the console doesn't show new errors), but Tone.start() might be failing silently. Or there's some other issue.

Let me check: maybe the issue is that the AudioContext can be started but Tone.start() is rejecting. Let me investigate by adding error logging, or perhaps check what Tone.start() actually does.

Actually, let me look at this from a different angle. The console warning "The AudioContext was not allowed to start" appears 2 times - those are from the initial page load (Tone.js tries to create the context). After clicking, we'd expect to see:
- A new log if it succeeded
- An error if it failed

But neither appears. This suggests the click might not be reaching the button, OR Tone.start() is hanging on the worker creation (since the blob: worker is being blocked by CSP).

Wait - Tone.js v14 uses AudioWorklet via blob URLs. If those are blocked, Tone.start() might fail to initialize the audio context properly. Let me check.

Looking at the error: "Creating a worker from 'blob:...' violates worker-src 'none'". This is a worker, not an AudioWorklet. But Tone.js v14 might use workers for offline rendering.

Actually, looking more carefully, the click might just not be triggering the button event. Let me try a different approach - use the keyboard's Enter key after focusing the button.

Or simpler: let me just add a click handler that doesn't require Tone.start() to be successful. Or let me set `audioReady = true` and skip the Tone.start() call if it fails.

Actually wait - looking at the code:
```js
async function startAudio() {
  try {
    await Tone.start();
    buildSynth();
    audioReady = true;
    gateEl.classList.add("hidden");
  } catch (err) {
    console.error("Audio start failed:", err);
    alert("...");
  }
}
```

If Tone.start() hangs, the gate stays. If it throws, we get an alert and console error. If it succeeds, the gate hides. None of these are happening, so... either the click isn't reaching the button, OR Tone.start() is hanging silently.

Hmm. Let me try a different approach. Let me click on the button area more carefully. Maybe my coordinate is slightly off. Looking at the image, the "Enable Audio" button text center is at approximately:
- x = 599 (looks right)
- y = 488 (the button extends from about y=475 to y=505)

Let me try to focus on the button first, then send Enter key. Or let me try slightly different y values.

Actually, let me try the simplest test: just do `inspect` after the click to see what happens to the DOM state.

Actually wait - maybe my issue is that the click action takes time, and during that time the screenshot is taken BEFORE the click was processed. Let me try doing multiple actions in sequence.

Actually, I think the click might be working but the page just shows the same screenshot because the click happened too fast. Let me explicitly take a screenshot AFTER the click to see the current state.

Looking back at my interactions, every click action immediately returns and shows the same screenshot. This is suspicious. The DOM is also always the same.

Maybe the click is being absorbed by the .gate overlay's backdrop, but not the button. Let me try this: add a click handler to the gate background that just dismisses the gate (for testing purposes), or change the button position.

Actually, let me try with a slightly different click coordinate. The button looks like it's centered at x=599 in the image, but maybe in the actual viewport it's slightly different. The image is 1200x800 so y=488 in the image corresponds to y=488 in viewport. Looking at the screenshot more carefully, the button text "Enable Audio" appears to be centered around y=488.

Let me try a completely different approach - use the page console to call the function directly. But I don't have console access...

Wait, I do have an action called "click" that can click at coordinates. Let me try clicking with a different y like 480 or 495.

Hmm, let me think about this differently. The browser tool returns immediately after the action. But after a click, the page should change. Let me look at the DOM output - if I look carefully, the DOM should show whether the gate is hidden or not.

Actually, looking at the latest DOM dump:
"Click to enable sound
Browsers require a user gesture before audio can start. Click below to activate the synthesizer.
Enable Audio"

This is the gate content. If the gate was hidden, this would not appear. So the gate is still visible.

Maybe the click action simply doesn't work in this environment for buttons inside an overlay. Let me try just sending a `key` event after focusing the button.

Actually, the simplest fix: let me add a global click handler on the gate itself that triggers the audio. Or make the audio start immediately on any click anywhere.

Let me modify the code to make it more robust:
1. Add a fallback that starts audio on any user gesture anywhere
2. Or use `pointerdown` instead of `click` for the button
3. Or just call Tone.start() in the button's `mousedown` event

Actually wait, let me just check the actual situation. Maybe the click works but the screenshot is taken before the change. Let me try doing click, then taking a screenshot in a separate call.

The click doesn't seem to be reaching the button. Let me try to make the audio start easier - I'll modify the code so that:
1. Clicking anywhere on the gate starts audio
2. Or remove the gate and just try to start audio directly

Actually, let me try a different tactic - let me make the code work even if Tone.start() fails (since this might be a sandbox limitation). I can simply try to start Tone in the constructor or any user gesture, with a graceful fallback.

But more importantly - the click IS happening, I believe. The issue is that Tone.start() may be hanging or failing. Let me add some debug logging to see what's happening.

Actually, I just realized - maybe the click action is being performed but Tone.start() Promise is never resolving in the sandboxed environment. Let me change the code to:
1. Always set audioReady=true after the user gesture (even if Tone.start fails)
2. Use Tone.context.resume() as a fallback

Let me also try a totally different approach: I'll just try clicking on the piano directly. If the gate is in the way, the click won't reach the piano. But if the gate is dismissable by any click, the gate would dismiss.

Let me update the code to be more robust:
- Make audio start on any click/touch/keydown
- Don't require Tone.start() to succeed
- Hide the gate after the user gesture regardless

This will ensure the user can interact with the piano even if audio is silently failing in the sandbox.

Actually, I realize there might be another issue. Let me look at the iframe sandbox settings. The warning says: "An iframe which has both allow-scripts and allow-same-origin for its sandbox attribute can escape its sandboxing."

This means the iframe has both allow-scripts and allow-same-origin. The CSP is `worker-src 'none'`. This blocks Tone.js from creating workers. Tone.js v14 might use workers for offline audio processing but not for regular playback.

Wait - actually looking at the error: "Creating a worker from 'blob:...'" - this is a regular Worker, not AudioWorklet. Tone.js might use a Worker for offline rendering only. For normal playback, it should work.

But the AudioContext warnings indicate that audio is suspended. After Tone.start() succeeds, the AudioContext should resume. If Tone.start() never resolves, the audio stays suspended.

Let me try one more approach - use the key action to send 'Enter' after focusing the button. Or use the click action with a slightly different coordinate.

Actually, let me just check if the click is even registering. I'll add a click handler on the gate background itself (not just the button) and make clicking anywhere on the gate start audio.

Or even simpler: let me change the code so the gate's click anywhere starts audio, and add a fallback that auto-dismisses the gate.

Let me update the code:
1. Make the gate dismiss on any click anywhere
2. Add a timeout fallback to dismiss the gate after 30s (but only if audioReady)
3. Add better error handling

Actually I just realized maybe the click action is delivering to a window-level pointer handler but not the button. Let me just make the entire gate clickable to start audio.

Let me also add a click-anywhere fallback to start audio. This will make the app more robust.

Now let me reload and try clicking.

Let me try clicking on the gate (anywhere) - the pointerdown should now trigger startAudio.

Excellent! The audio activated! "Audio ready" appears in the console. The gate is gone, and the piano is visible. I can see:
- All 7 white keys: C4, D4, E4, F4, G4, A4, B4, C5 (8 white keys total - C4, D4, E4, F4, G4, A4, B4, C5 = 8 whites)
- 5 black keys: C#4, D#4, F#4, G#4, A#4
- Computer key labels at the top
- Each key has its letter and note name visible

The layout looks correct. The keyboard is centered around the piano area. Let me check:
- White keys labeled: C4 (A), D4 (S), E4 (D), F4 (F), G4 (G), A4 (H), B4 (J), C5 (K) ✓
- Black keys labeled: C#4 (W), D#4 (E), F#4 (T), G#4 (Y), A#4 (U) ✓

Now let me test playing some notes. I'll click on the C4 key first.

Looking at the piano image, the piano starts at around x=345 and ends at x=850. The C4 key is the first white key on the left. With 8 white keys, each is about (850-345)/8 = ~63px wide. So C4 is around x=375 (345 + 31), y=440.

Let me try clicking C4.

The click is too fast - the highlight is removed immediately because pointerdown then pointerup happen quickly. I need to test holding the key down. Let me use `motion` to capture frames during a click, or check the highlighted state by inspecting the DOM.

Actually, let me verify the audio playback by looking at the held notes in the global __piano object. The screenshot doesn't show a highlighted key because the click is a quick press+release.

Let me check if the note was actually triggered by looking at the DOM. Or let me try the motion action to capture frames during a press.

Actually, since the click is very quick, I should try to:
1. Use the motion action to see if highlight works during a press
2. Or use keyboard input which I can hold down

Let me try a keyboard press first.

The `key` action seems to send a single key press which fires both keydown and keyup immediately, so the highlight won't be visible in the screenshot.

Let me try the `motion` action which captures multiple frames over time, while pressing a key. This might let me see the highlight during the press.

Actually, let me look at this from a different angle. The "key" action with just text sends a quick keydown+keyup. The highlight will only appear for the brief instant between them.

Let me use the motion action which captures multiple frames over time. The default duration is 1000ms. If I can keep a key held during that time, I might see the highlight.

Actually, looking at the browser tool more carefully, the actions are:
- click: sends a mousedown/mouseup at coordinates
- key: sends a key event (probably keydown+keyup)
- motion: captures frames over time
- drag: drag from one point to another

I don't have a way to "hold" a key in the browser tool. But I can use motion to capture multiple frames and observe state changes.

Let me try a different approach - use `evaluate` style behavior by typing text and then checking DOM state. Actually, I don't have that either.

Wait, let me check if motion would help - maybe motion runs in the background while I trigger actions.

Actually, the simplest test is to just verify functionality works without trying to capture the highlight visually. I can:
1. Check that notes are being played (no error logs)
2. Check that the held set works
3. Verify by inspecting the DOM after a key press

Let me just trust that the code works and move on. The screenshot doesn't capture the brief highlight during a click.

Actually wait, I can verify by looking at the held notes via the __piano debug object. Let me see if I can read the JS state.

Hmm, I can't directly run JS. But I can do this:
- The console shows logs from my code
- If a note is being held when the page is examined, the highlight should be in the DOM

Let me think about this more. The key action sends keydown then keyup. Both happen immediately. So the highlight is applied then removed within milliseconds.

I should verify the code is correct by examining it carefully. Let me re-read the key handlers:

```js
window.addEventListener("keydown", (e) => {
  if (!audioReady) return;
  if (e.repeat) return;
  if (e.ctrlKey || e.metaKey || e.altKey) return;
  const k = e.key.toLowerCase();
  const note = keyToNote[k];
  if (!note) return;
  e.preventDefault();
  physicalKeysDown.add(k);
  noteOn(note);
});

window.addEventListener("keyup", (e) => {
  if (!audioReady) return;
  const k = e.key.toLowerCase();
  const note = keyToNote[k];
  if (!note) return;
  physicalKeysDown.delete(k);
  noteOff(note);
});
```

This looks correct. Each keydown triggers noteOn (which adds to held set, calls triggerAttack, and adds 'active' class). Each keyup triggers noteOff (which removes from held set, calls triggerRelease, removes 'active' class).

The duplicate prevention is in `noteOn`:
```js
function noteOn(note) {
  if (!audioReady || !synth) return;
  if (held.has(note)) return; // already held -> prevent duplicates
  ...
}
```

The auto-repeat prevention is in keydown:
```js
if (e.repeat) return;
```

These look correct.

The `releaseAll` function releases all held notes and is called on window blur and visibility change. Good.

For mouse:
- pointerdown -> noteOn
- pointerup -> noteOff
- pointerleave -> noteOff
- pointercancel -> noteOff
- Document-level pointerup outside the piano -> releaseAll

This should handle the case of releasing the pointer outside a key.

I think the code is correct. Let me also verify with the motion action to try to capture the highlight visually.

The motion frames all show the same state - no highlighted keys. This is because:
1. The motion action captures frames over time, but I haven't pressed anything during it
2. The single click happens too fast to capture

Let me think about how to test the press-and-release highlighting visually. The only way I can really do this is to:
1. Hold down a key (somehow)
2. Take a screenshot during the hold

But the browser tool doesn't seem to have a "hold" action. The `click` is fast, and `key` is fast.

I can verify the code logic by reading it carefully. The code is correct - the highlight is added on noteOn and removed on noteOff. The CSS for `.white.active` and `.black.active` is set up properly.

Let me instead verify by inspecting the DOM after a key press to see the active class. Actually, the DOM doesn't include the class state - it just shows text content.

Let me try one more approach - drag the cursor with motion. The drag action might trigger the press state. But drag also releases when complete.

OK, I'll just trust the code. Let me verify the implementation by re-reading and looking at all the requirements:

1. ✅ Display one chromatic octave from C4 through C5 with correctly placed black and white keys and visible note labels - YES, 13 keys rendered
2. ✅ Map computer keys A W S E D F T G Y H U J K in order to those 13 notes - YES, keyMap defined
3. ✅ Pressing a screen key or its computer key starts the note; releasing it starts the envelope's release phase - YES, noteOn/noteOff with triggerAttack/triggerRelease
4. ✅ Use a synthesized voice with an ADSR envelope - YES, PolySynth with Synth and envelope ADSR
5. ✅ Support at least three simultaneous notes - YES, PolySynth with maxPolyphony=8
6. ✅ Highlight keys while held - YES, active class added/removed
7. ✅ Prevent keyboard auto-repeat from creating duplicate sustained voices - YES, e.repeat check + held.has check
8. ✅ Release held voices when the pointer is released outside a key - YES, document-level pointerup
9. ✅ Release when window loses focus - YES, blur and visibilitychange handlers
10. ✅ Activate audio through a user gesture - YES, gate with startAudio on click
11. ✅ Synthesize all sound without audio files - YES, Tone.Synth
12. ✅ Display the computer-key mapping - YES, keymap at top

All requirements are met. The code should work correctly when used in a real browser environment.

Let me also verify the layout once more by looking at the screenshot. The piano has:
- 8 white keys: C4 (A), D4 (S), E4 (D), F4 (F), G4 (G), A4 (H), B4 (J), C5 (K) ✓
- 5 black keys: C#4 (W), D#4 (E), F#4 (T), G#4 (Y), A#4 (U) ✓
- Black keys correctly placed between white keys ✓
- Each key has note label and computer key hint ✓
- Keymap legend at top shows all mappings ✓

The piano layout is correct. The black keys are positioned between the white keys:
- C#4 between C4 and D4 ✓
- D#4 between D4 and E4 ✓
- F#4 between F4 and G4 ✓
- G#4 between G4 and A4 ✓
- A#4 between A4 and B4 ✓

Note that E4 and F4 have no black key between them (E# = F), and B4 and C5 have no black key between them (B# = C). This is correct for piano layout.

Now let me verify the DOM structure once more to confirm everything is in place.

No errors in the console. The click on C4 didn't throw any errors. The note was triggered and released cleanly. 

Now let me try clicking a black key (C#4) to verify those work too. C#4 should be at approximately the boundary between C4 and D4. C4 is around x=378, D4 is around x=440. So C#4 center should be around x=409, y=380 (upper part of black key).

Actually looking at the image, black keys start at y around 327 and end at y around 422. The C#4 black key is between C4 and D4 white keys. With white keys around 60px wide, C#4 center is at around x=409.

No errors. The black key click worked too. No exceptions, no console errors. The synth is functional.

Now I want to verify the high-level functionality:
1. The audio context is running
2. The synth is created
3. The note handlers are wired up

Let me also verify by running a quick check on the JS source. Let me re-read the relevant parts of the file.

The code looks correct. Let me verify all the requirements one more time:

1. ✅ Display one chromatic octave from C4 through C5 - 13 notes in NOTES array
2. ✅ Correctly placed black and white keys - layoutBlackKeys() positions them at proper boundaries
3. ✅ Visible note labels - each key has a `.note-label` div with the note name
4. ✅ Map computer keys A W S E D F T G Y H U J K - keyToNote object built from NOTES
5. ✅ Pressing screen key starts note, releasing starts release - pointerdown/pointerup handlers
6. ✅ Keyboard press starts note, release triggers release phase - keydown/keyup handlers
7. ✅ ADSR envelope - PolySynth with envelope (attack, decay, sustain, release)
8. ✅ At least 3 simultaneous notes - PolySynth with maxPolyphony=8
9. ✅ Highlight keys while held - .active class added on noteOn, removed on noteOff
10. ✅ Prevent keyboard auto-repeat duplicates - e.repeat check + held.has check
11. ✅ Release held voices when pointer released outside key - document-level pointerup handler
12. ✅ Release when window loses focus - blur and visibilitychange handlers
13. ✅ Activate audio through user gesture - gate with click handler
14. ✅ Synthesize all sound without audio files - Tone.Synth
15. ✅ Display computer-key mapping - keymap at top with kbd elements

Everything looks good. The audio activated, no errors on clicks, the layout is correct.

The only thing I haven't been able to verify visually is the press-and-release highlighting. But the code is correct - the highlight class is added/removed at the right points.

Let me also check that the file is saved properly.

Good. The index.html is 17KB and tone.min.js is 349KB. Both files are in place.

Let me summarize what was built and what I verified:

## What I built:
A single-page playable piano keyboard with:
- One chromatic octave from C4 through C5 (13 notes: 8 white + 5 black)
- Tone.js PolySynth with ADSR envelope
- Computer keys A W S E D F T G Y H U J K mapped to the 13 notes
- Mouse/touch and keyboard input
- Press-and-release highlighting
- Held notes tracking to prevent duplicates from auto-repeat
- Safety release on window blur and pointer-up outside piano
- Audio activation via user gesture (click on gate)
- Visible computer-key mapping legend
- Visual feedback (highlight, color changes)

## What I verified:
1. ✅ Page loads successfully with no JS errors
2. ✅ Tone.js v14.8.49 loads as global `Tone`
3. ✅ Audio gate appears initially
4. ✅ Clicking the gate (or anywhere on it) activates audio - "Audio ready" log appears
5. ✅ Gate is dismissed after activation
6. ✅ Piano layout renders correctly:
   - 8 white keys: C4, D4, E4, F4, G4, A4, B4, C5
   - 5 black keys: C#4, D#4, F#4, G#4, A#4 (correctly positioned between white keys)
   - Each key has note name and computer key label
7. ✅ Keymap legend at top shows all 13 mappings
8. ✅ Clicking C4 (white key) doesn't throw errors
9. ✅ Clicking C#4 (black key) doesn't throw errors
10. ✅ Console has no errors after audio activation and key presses

## What I couldn't verify visually:
- The press-and-release highlight (because clicks and key events in the browser tool are instantaneous - the highlight is added then removed within milliseconds, so it doesn't show in the screenshot)
- Actual sound output (browser tool doesn't play audio, and the AudioContext might be suspended in the sandbox)

However, the code logic is correct:
- `noteOn` adds the 'active' class
- `noteOff` removes the 'active' class
- CSS has `.white.active` and `.black.active` styles with color changes

The code will work correctly when used in a real browser.