What qwen3.8-flash-next-strata did

Let me start by exploring the working directory.

Then build the game.

Let me plan the implementation carefully.

Key design:
- Canvas 960x600 CSS pixels, with devicePixelRatio scaling for crispness.
- Fixed timestep accumulator for frame-rate independence? The requirement says movement scaled by elapsed time. I'll use a fixed-timestep physics accumulator with substeps — that guarantees no tunneling and frame-rate independence. Use dt clamped.

Physics: ball speed increases as bricks destroyed, capped. Use swept collision via substeps: compute number of substeps based on max movement per substep relative to smallest dimension (brick height ~ 24, ball radius ~ 8). Use step size = min radius*0.5 etc.

Better approach: continuous collision detection with segment-vs-AABB sweep. But simpler robust approach: substepping with small steps (e.g., max movement per substep = 4 px) plus proper AABB circle collision resolution. That prevents tunneling through bricks (brick height 24, min dimension 24; step 4 px is fine). Also prevents sticking: after resolving a brick collision, push ball out of brick and mark that brick as hit, and remove brick from grid so no repeated collision.

Let me implement circle-vs-rect collision with closest point, and resolve by reflecting along the normal from closest point, and repositioning ball outside.

For robustness, I'll do a swept approach: within each substep, move ball in small increments.

Let me write the collision:

```
function collideBricks(ball) {
  // find candidate cells overlapping ball's AABB
  ...
}
```

Grid: bricks array of {x,y,w,h,hits,alive,color}.

Collision detection: compute closest point on rect to circle center; if dist < r, collision. Determine normal:
- If center is inside rect expanded... handle by finding minimal penetration axis.

Standard approach:
```
const cx = clamp(b.x, rx, rx+rw), cy = clamp(b.y, ry, ry+rh);
const dx = b.x - cx, dy = b.y - cy;
const d2 = dx*dx + dy*dy;
if (d2 > r*r) continue;
// collision
let nx, ny;
if (d2 > 0) { const d = Math.sqrt(d2); nx = dx/d; ny = dy/d; }
else {
  // center inside rect: push out along smallest overlap axis
  const left = b.x - rx, right = rx+rw - b.x, top = b.y - ry, bottom = ry+rh - b.y;
  const m = Math.min(left,right,top,bottom);
  if (m === left) { nx=-1; ny=0; } else if (m===right){nx=1;ny=0;} else if (m===top){nx=0;ny=-1;} else {nx=0;ny=1;}
}
// reposition
const pen = r - Math.sqrt(d2);
b.x += nx*(pen+0.01); b.y += ny*(pen+0.01);
// reflect
const dot = b.vx*nx + b.vy*ny;
if (dot < 0) { b.vx -= 2*dot*nx; b.vy -= 2*dot*ny; }
```

Only reflect if moving toward the surface. Also ensure after reflection the velocity has a component away from the surface: if dot after reflection is such that (v·n) <= 0, force it positive: `if (b.vx*nx + b.vy*ny < 0) { ... }`. Actually after reflection with dot<0, v·n becomes -dot > 0. Good.

Only one brick collision per substep to avoid weird double-bounce? Handle all overlapping but that's fine; better to break after first hit per substep to keep it simple and predictable. I'll break after first brick hit.

Paddle collision: paddle is a rect near bottom. If ball moving down and intersects paddle top: reflect with angle based on offset. Also handle sides.

Paddle: y = H - 34 - paddleH? Let's define: field 960x600. Paddle width 110, height 16, y = 600 - 16 - 10 = 574. Ball radius 8.

Ball off bottom: if b.y - r > H → lose life.

Walls: left x < r → x = r, vx = -vx. Right similar. Ceiling y < r → y=r, vy=-vy.

Paddle deflection: 
```
const hitPos = clamp((b.x - (paddle.x)) / paddle.w, 0, 1) → offset = (hitPos - 0.5)*2 in [-1,1]
angle = offset * maxAngle (e.g. 60 deg from vertical)
speed = current speed
b.vx = speed * sin(angle); b.vy = -speed*cos(angle)
```
Ensure vy is sufficiently negative (min |vy| to avoid near-horizontal infinite loops). Also enforce a minimum vertical component overall: after any bounce, clamp angle to be within e.g. 75° of horizontal? Standard: keep |vy| >= 0.3*speed maybe. Let's enforce min vertical component: if |vy| < 0.25*speed → set vy = sign*0.25*speed and renormalize vx.

Speed: base 380 px/s, +6 px/s per brick destroyed? 40 bricks → +240 → 620. Cap at 700. Let's do speed = min(base + destroyed*7, 720).

Substeps: maxStep = 3 px. steps = ceil(dist/maxStep) where dist = speed*dt. dt clamped to 1/30 s. At speed 720 and dt 1/30 → 24 px → 8 substeps. Fine.

Actually with substepping, I need to move in increments and check collisions each increment. Implement:

```
const remaining = dt;
const maxMove = 3;
while (remaining > 1e-6) {
  const speed = Math.hypot(vx,vy);
  const stepTime = Math.min(remaining, maxMove / Math.max(speed, 1));
  move(stepTime);
  remaining -= stepTime;
}
```

That's clean.

Also cap dt total per frame to avoid huge catch-up: dt = min(elapsed, 0.05).

Bricks: 8 cols x 5 rows. Field width 960. Margin: left/right 60 each? Let's compute: brick area from x=60 to 900 → width 840. gap 8. brick w = (840 - 7*8)/8 = (840-56)/8 = 98. Rows: top offset 70, brick h = 26, gap 8 → rows at 70, 104, 138, 172, 206. Bottom of last row = 232. Good.

Top two rows take 2 hits: rows 0 and 1. Damaged visual: draw with a crack / darker color / smaller inner rect.

Score: 10 per brick hit, 50 for destroying. So a 2-hit brick gives 10 + 10 + 50 = 70.

Lives: 3. Show hearts drawn on canvas? Score and lives visible during play — draw on canvas HUD (graphics drawn with canvas API) and also maybe in DOM. Requirement: "Draw all the graphics with the canvas API." HUD text on canvas is fine. Controls shown on page outside canvas in DOM.

Juice: 
- particles on brick destroy and on hit
- brick flash (white flash overlay fading)
- screen shake (translate canvas)
- ball trail (store previous positions)
- WebAudio synthesized blips
- maybe subtle background gradient, vignette.

Pause on P or window blur. Pause overlay drawn on canvas.

Restart: R key or button (DOM button outside canvas? "offer a restart" — I'll support both: click on canvas / press R / Enter, plus a DOM button). Let's add a DOM button "Restart" in the controls area, plus keyboard.

Mouse control: paddle follows cursor x. But arrow keys also control. Approach: if mouse moves over canvas, set target x = mouse; arrows set a velocity-based target. Implement: paddle.x follows targetX. Mouse sets targetX directly. Arrows move targetX at 900 px/s. Actually simpler: paddle.x directly set by mouse (with clamping), and arrows move paddle.x at speed. But then mouse and keys conflict only in that both move it — fine.

I'll do: `paddleTargetX` updated by mouse; arrows adjust paddleTargetX; paddle.x lerps toward target quickly (or set directly). Direct set for mouse feels responsive. Let's do: paddle.x = target, with target updated by mouse instantly and by arrows continuously. Lerp with factor 1 - exp(-dt*30) for smoothness. Hmm, mouse-following with lerp adds slight lag which is fine and feels good. But for arrow keys, lerp is fine too.

Actually for a breakout, direct mouse follow is best. I'll use a fast lerp (time constant ~ 1/40 s) — practically instant.

Also mouse move should launch? "launches on Space or a click" — click on canvas launches.

Also when ball is stuck, it sits on paddle at offset position.

Let me also handle: click anywhere on page launches? Use canvas click. Also prevent text selection.

devicePixelRatio: canvas.width = 960*dpr, style width 960px. ctx.scale(dpr,dpr). Handle resize? Keep simple: set once, and on dpr change re-setup. I'll implement setupCanvas() that reads dpr and sets sizes.

Screen shake: shake magnitude decays; apply ctx.translate(random offsets) before drawing world.

Trail: store last N positions with time; draw fading circles.

Sound: WebAudio; create AudioContext lazily on first user gesture (click/keydown). Functions: beep(freq, dur, type, gain). Brick hit: short square blip with pitch rising with combo/destroyed count. Destroy: noise burst + lower tone. Wall: short sine. Paddle: triangle. Lose life: descending saw. Win: arpeggio.

Mute toggle? Add 'M' key maybe. Keep it simple but nice: add a small sound indicator in DOM controls. Let's add mute button in DOM.

Also need to ensure AudioContext resume on gesture.

Let me also add a subtle "aim guide" line when ball is stuck? Nice juice: show launch direction indicator. Keep minimal.

Now let's think about the win/lose states: state machine: 'ready' (ball stuck, waiting launch), 'playing', 'paused', 'won', 'lost'. Also maybe 'life-lost' brief pause then back to 'ready'.

Full reset: rebuild bricks, score 0, lives 3, speed base, particles cleared, shake 0.

Let me write the code.

Structure:
- index.html: styles, canvas, controls panel, restart button, sound toggle.
- game.js: everything.

Let me write carefully.

```js
(() => {
'use strict';
const W = 960, H = 600;
const canvas = document.getElementById('game');
const ctx = canvas.getContext('2d');
let dpr = 1;

function setupCanvas() {
  dpr = Math.max(1, Math.min(window.devicePixelRatio || 1, 2));
  canvas.width = Math.round(W*dpr);
  canvas.height = Math.round(H*dpr);
  canvas.style.width = W+'px';
  canvas.style.height = H+'px';
  ctx.setTransform(dpr,0,0,dpr,0,0);
}
```

Colors: rows palette: ['#f6c445','#f2765f','#e05299','#7c6cf0','#4fc0f0'] maybe. Damaged bricks: draw darker + cracks.

Brick drawing: rounded rect with gradient, top highlight.

Let me write helper roundRect (implement manually for compatibility, though ctx.roundRect exists in modern browsers; implement own to be safe).

HUD: score left, lives hearts right, and level/bricks remaining maybe.

Let me write the code now.

Particles: array of {x,y,vx,vy,life,maxLife,color,size}. Update with gravity, fade.

Flash: bricks have `flash` value set to 1 on hit, decays; draw white overlay with alpha flash.

Screen shake: `shake` value; each frame shake *= exp(-dt*8); offset = (rand-0.5)*shake.

Ball trail: array of {x,y} pushed each substep? Better each frame push current pos, cap length 18. Draw as circles with decreasing alpha and radius.

Also glow: draw ball with radial gradient.

Let me handle the paddle drawing: rounded rect with gradient, slight glow.

Background: dark navy with subtle grid lines and vignette. Draw a border frame.

Now the collision ordering per substep:
1. move ball
2. check walls/ceiling
3. check paddle
4. check bricks (break after first)
5. check bottom out

Careful: check paddle before bricks (bricks are at top, no overlap issue).

Paddle collision detail: paddle rect (px, py, pw, ph). Use circle-rect closest point. If colliding and normal has ny < 0 (ball above paddle surface, normal pointing up), apply angle-based reflection. If normal is horizontal (hit the side), reflect horizontally only (vx = -vx) — classic behavior. Let's implement: compute nx, ny as in generic. If ny < -0.5 → top hit → angle-based. Else → side hit → vx = -vx, push out horizontally.

Also handle ball hitting paddle from below? Rare; treat as generic.

Bottom loss: if b.y - r > H + 4 → lose life.

Also guard: if ball somehow gets stuck with tiny vy, enforce min |vy| >= 0.35*speed when in play? Careful: near-horizontal ball bouncing between walls forever is a known stall. Enforce after paddle/brick/wall bounces: if |vy| < 0.3*speed, adjust. Let's implement a function `enforceAngle(spread)` that clamps the velocity direction so that |vy| >= 0.28*speed and |vx| <= 0.96*speed, preserving sign of vy (if vy == 0, set negative).

Apply after brick bounce and wall bounce. For wall bounce, if vy too small, adjust.

Let me write `normalizeVelocity()`:
```
function clampDirection() {
  const s = Math.hypot(b.vx, b.vy) || 1;
  let minVy = 0.30*s;
  if (Math.abs(b.vy) < minVy) {
    const sy = b.vy >= 0 ? 1 : -1;
    b.vy = sy*minVy;
    b.vx = (b.vx >= 0 ? 1 : -1) * Math.sqrt(Math.max(s*s - b.vy*b.vy, 1));
  }
  // recompute to keep speed constant
}
```
Hmm, this changes direction but keeps speed s. Good.

Also cap max angle from vertical for paddle: max 62°.

Speed management: store `speed` variable; after each bounce set velocity magnitude to speed. Actually simpler: keep speed as the canonical magnitude, and set vx = speed*sin(angle), vy = -speed*cos(angle) on paddle bounce. On wall bounce, reflect and renormalize to speed. On brick bounce, reflect and renormalize to speed.

Let me define `setSpeed()` that renormalizes velocity to `speed`.

Now lives lost: state 'ready', ball stuck. Also brief "life lost" flash message.

Let me write the code.

Also pause: on blur → if state playing/ready → paused with reason 'focus'. On focus, stay paused until user resumes (press P or click)? Requirement: "Pause on P or when the window loses focus." I'll auto-resume on focus? Safer: pause on blur; on focus, show "Paused — press P to resume". Hmm, that could be annoying but is explicit. I'll auto-resume on focus if it was auto-paused... Actually many implementations auto-resume. I'll show overlay "Paused" and resume on click/P/any key. Let's keep: on blur, pause. On focus, keep paused and show "click to resume" — clear and safe. Hmm, but if the user alt-tabs back and just clicks to launch... clicking resumes. Fine. Actually let me auto-resume on focus after a short delay only if the pause was due to focus loss. That's friendlier. I'll do: on focus, if pausedBy === 'blur', resume. And show overlay while blurred (though nothing renders while blurred... rAF may still run). I'll keep rAF running and draw the pause overlay.

Hmm — when window loses focus, rAF may be throttled. On return, dt would be huge but we clamp dt to 0.05, and we auto-resume. Fine.

Also document.visibilitychange → pause.

Let me now write files.

I'll write index.html first.

Design of page: dark background, centered canvas, title, controls list below. Use system fonts (no external fonts): font-family: ui-monospace, "SFMono-Regular", Menlo, Consolas, monospace — available locally.

Let me write.

For the DOM: 
```html
<main class="wrap">
  <header>...</header>
  <div class="stage"><canvas id="game" width="960" height="600" tabindex="0"></canvas></div>
  <section class="controls">...</section>
</main>
```

Buttons: Restart, Sound on/off.

Now write game.js. Let me be thorough.

```js
(function(){
'use strict';

const W = 960, H = 600;

// ---------- canvas setup ----------
const canvas = document.getElementById('game');
const ctx = canvas.getContext('2d');
let scale = 1;
function setupCanvas(){
  const dpr = Math.max(1, Math.min(window.devicePixelRatio || 1, 2));
  canvas.width = Math.round(W*dpr);
  canvas.height = Math.round(H*dpr);
  canvas.style.width = W + 'px';
  canvas.style.height = H + 'px';
  scale = dpr;
}
```
Then in render: ctx.setTransform(scale,0,0,scale, shakeX*scale, shakeY*scale).

Wait, translate in device pixels: setTransform(scale, 0, 0, scale, shakeX*scale, shakeY*scale) → translate by shakeX CSS px. Good.

Constants:
```
const BRICK_COLS = 8, BRICK_ROWS = 5;
const FIELD_PAD = 56; // left/right
const BRICK_TOP = 74, BRICK_GAP = 8, BRICK_H = 26;
const BRICK_W = (W - FIELD_PAD*2 - BRICK_GAP*(BRICK_COLS-1)) / BRICK_COLS; // (960-112-56)/8 = 792/8 = 99
```
99 wide, 26 tall. Good.

Paddle: PW=112, PH=16, PY = H - 40 = 560. Ball radius 8. Ball start y = PY - R - 1.

Ball off bottom when y - R > H? Let's use y - R > PY + PH + 6? No — the ball should be able to fall past the paddle. Loss when y - R > H.

Hmm, but the gap between paddle bottom (576) and H (600) is 24px — fine.

Colors per row:
row0: '#ff5d5d' (2 hits)
row1: '#ff9f43' (2 hits)
row2: '#ffd93d'
row3: '#6ee7b7'
row4: '#5aa9ff'

Damaged bricks: draw with cracks and reduced brightness.

Let me write the full code.

```js
const ROW_COLORS = [
  {fill:'#ff6b6b', light:'#ffa3a3', dark:'#c0392b', hits:2},
  ...
];
```

Brick object: {x,y,w,h,maxHits,hits,color index,alive,flash}.

hitBrick(brick): score += 10; brick.hits--; brick.flash = 1; if (brick.hits<=0){ alive=false; destroyed++; score+=50; speed up; particles burst; shake bigger; sound destroy } else { sound hit; shake small; few particles }.

Speed: `speed = Math.min(MAX_SPEED, BASE_SPEED + destroyed * SPEED_STEP)`. BASE 360, STEP 8, MAX 760. 40 bricks → 360+320=680. Good.

Now the render function.

Draw order: background, bricks, paddle, trail, ball, particles, HUD, overlays.

Background: fill '#0b1020'; subtle grid; border frame lines at edges (walls) so player sees boundaries.

Let me draw wall bands: left/right 4px accent lines and top band.

Actually the ball bounces at x=R and x=W-R, so the visual wall should be at x=0..? Let's define playfield inset: walls at x=0 and x=W visually, ball bounces at R from edge. Fine — draw a 3px neon border at the edges.

HUD: top area? Bricks start at y=74, so HUD at y=30. Score text left at x=24, lives hearts at right.

Hmm, ceiling bounce at y=R=8, HUD text at y ~ 30 would overlap ball path. Ball can travel above bricks in the region y 8..74. HUD text there could be overlapped by the ball — acceptable but slightly ugly. Alternative: put HUD in the bottom area near the paddle, e.g., y = 590? Paddle at 560-576, bottom band 576-600. Put HUD text at y=592 centered-ish. Let's put score at bottom-left (x=24, y=592) and lives at bottom-right. And "bricks remaining" maybe. That avoids overlap. Good.

Actually let me reserve a bottom HUD strip: paddle PY = H - 46 = 554, paddle bottom 570, HUD baseline at 590. Good.

Let me set PY = 548, PH = 16 → bottom 564. HUD text baseline 588.

Ball trail: array of positions; push in update each substep (limit by distance). Cap 24 entries.

Particles: cap ~400.

Sound:
```js
let audioCtx = null, masterGain, muted=false;
function ensureAudio(){ if(!audioCtx){ const AC = window.AudioContext||window.webkitAudioContext; if(!AC) return; audioCtx = new AC(); masterGain = audioCtx.createGain(); masterGain.gain.value = 0.35; masterGain.connect(audioCtx.destination);} if(audioCtx.state==='suspended') audioCtx.resume(); }
function tone({freq=440, freqEnd, dur=0.12, type='square', gain=0.3, delay=0}){...}
function noise({dur, gain}) { buffer noise + filter }
```

Brick hit: tone square 320 + destroyed*8 → freq ramp up. Destroy: noise burst + tone triangle low.
Wall: sine 220 short. Paddle: triangle 180 with pitch based on hit offset.
Life lost: sawtooth descending 300→80, 0.5s.
Win: sequence of notes.
Launch: short blip.

Now write it.

Also handle keyboard: prevent default for arrows/space to avoid page scroll.

Mouse: mousemove on canvas → compute x in CSS px relative to canvas rect: (e.clientX - rect.left) * (W / rect.width). Since rect.width = 960 normally, but if page is zoomed, ratio handles it.

Also mouse outside canvas? Only canvas. Also allow mousemove on window to keep paddle following? Restrict to canvas for clarity, but follow within stage. I'll attach to canvas and also to document for smoother feel? Just canvas.

Click on canvas: if state ready → launch; if won/lost → restart; if paused → resume.

Touch support: add touchmove for mobile? Not required but cheap. I'll add pointer events instead of mouse: use pointermove/pointerdown which covers mouse and touch. Good — use pointer events.

Keyboard: Space (launch), ArrowLeft/Right (move), P (pause toggle), R (restart), Enter (restart when game over), M (mute).

Key repeat for arrows: track keysDown set.

Now the update loop:

```js
let last = performance.now();
function frame(now){
  let dt = (now - last)/1000; last = now;
  if (dt > 0.05) dt = 0.05;
  if (dt < 0) dt = 0;
  update(dt);
  render();
  requestAnimationFrame(frame);
}
requestAnimationFrame(frame);
```

update(dt): always update particles/shake/flash decay (even when paused? no — freeze when paused). Update HUD animations.

When state is 'ready', paddle still moves, ball follows paddle.

Let me write update:
```js
function update(dt){
  time += dt;
  if (state === 'paused') return;
  updatePaddle(dt);
  if (state === 'playing') updateBall(dt);
  else if (state === 'ready') { ball.x = paddle.x + ball.stickOffset; ball.y = paddle.y - R - paddle.h/2 ... }
  updateParticles(dt);
  shake *= Math.exp(-dt*7); if (shake<0.05) shake=0;
  bricks flash decay
}
```

Wait, paddle.y: define paddle.y as top of paddle. Ball stuck: ball.y = paddle.y - R.

stickOffset: when ball is stuck, keep offset 0 (centered) or last offset? Centered is standard. I'll keep 0.

Launch: angle = random between -35° and 35° from vertical, biased toward center? Use offset based on nothing → random. Let's launch toward the side the paddle is moving, or just random ±30°. I'll use: dir = (Math.random()*0.6 - 0.3) → ±0.3 → ±17.4°... Let's do ±30° random. vy negative.

updateBall(dt) with substeps:

```js
function updateBall(dt){
  let remaining = dt;
  const maxStep = 3.0;
  let guard = 0;
  while (remaining > 1e-6 && guard++ < 500) {
    const sp = Math.hypot(ball.vx, ball.vy);
    const step = Math.min(remaining, maxStep / Math.max(sp, 1));
    stepMove(step);
    remaining -= step;
    if (state !== 'playing') break; // life lost
  }
}
```

stepMove(t): ball.x += vx*t; ball.y += vy*t; then collisions.

Collisions in stepMove:
```
// walls
if (ball.x - R < 0) { ball.x = R; ball.vx = Math.abs(ball.vx); sfx.wall(); addShake(2); }
else if (ball.x + R > W) { ball.x = W - R; ball.vx = -Math.abs(ball.vx); ... }
if (ball.y - R < 0) { ball.y = R; ball.vy = Math.abs(ball.vy); ... }
if (ball.y - R > H) { loseLife(); return; }
// paddle
if (ball.vy > 0 && circleRectHit(paddle)) { ... }
// bricks
```

Careful ordering: check bottom loss before paddle? If ball.y - R > H it's below the field; paddle is at 548..564, so ball would have hit paddle earlier if aligned. Fine.

Paddle check: only when moving downward and ball's bottom is near paddle top. Use generic circle-rect test.

Let me write circleRect(bx,by,r, rx,ry,rw,rh) returning {nx,ny,pen} or null.

Brick collision: iterate over bricks whose AABB overlaps ball AABB. To be efficient, compute grid indices from position:
```
const c0 = Math.floor((ball.x - R - BRICK_LEFT)/ (BRICK_W+GAP)) ... 
```
Not exact due to gaps. Simpler: loop over all alive bricks (40 max) — trivial cost. Do that.

Break after first hit.

After brick hit: reflect, renormalize speed to `speed`, clampDirection, add flash, particles at contact point, shake, score.

Contact point: ball position minus n*R.

Now, one subtlety: if the ball hits a brick and the brick is destroyed, the ball is pushed out so it won't re-hit. Good. If brick survives (2-hit), the ball is pushed out too, so no sticking.

Another subtlety: ball hitting the corner between two bricks — handled by breaking after first.

Potential issue: ball squeezed between two bricks in a gap of 8px with R=8 → could be pushed into the neighbor. With substeps of 3px and push-out, should be OK. The gap is 8px < 2R=16, so a ball entering a gap from below would collide with both sides. It gets pushed out along the closest-point normal, which for a ball in the gap moving up would be... Let's think: ball center at gap center, moving up. Closest point on left brick is its right edge → normal points left (dx negative) → push left, reflect vx. Then next substep it may hit the right brick. It could jitter but the substep loop handles each step separately, and after reflection vy is unchanged (still up) so it continues upward while being nudged sideways. It will pass through the gap since gap height is 26 (brick height) and the ball is 16 wide — it fits vertically but not horizontally in the 8px gap. Hmm, the ball would be pushed sideways into a brick repeatedly.

Wait: the gap between bricks is horizontal 8px. A ball of radius 8 (diameter 16) moving up into the gap: it can't fit. It will collide with the left brick's right face and the right brick's left face alternately, being pushed back and forth, while vy carries it up into the region above... but the bricks occupy y from BRICK_TOP to BRICK_TOP+26 for that row. If the ball is at the gap between two bricks in row 0 and moving up, it collides with side faces, gets vx flipped, but vy continues up. It will rise through the row's height (26px) while oscillating horizontally, and once above the row it's free. But it also hits the ceiling. Actually the ball would hit the brick faces and be pushed out horizontally by penetration amount each substep — penetration is small (3px max), so it climbs. It would end up damaging both bricks' side faces. That's acceptable behavior physically (the ball squeezes through the gap, hitting both bricks). It won't get stuck because vy is preserved. But could it get stuck if vy is small? clampDirection enforces |vy| >= 0.3*speed, so it always moves vertically enough. Good.

But there's a risk: reflection on a vertical normal flips vx, and if the ball is pushed left out of the right brick, then next substep it's overlapping the left brick, pushed right... net horizontal drift ~0 but it climbs. Fine. And each collision damages a brick, which is fine (score).

To reduce weirdness, I could make the gap bigger: 10px. Still < 16. Alternatively make ball radius 7 and gap 10. Whatever — it's fine and won't break the game.

Actually, a cleaner approach: when the ball hits a brick's side face while moving mostly vertically, prefer reflecting the dominant axis. My closest-point normal handles it correctly.

Let me also add: after brick collision, only one collision per substep (break). Good.

Now, "The ball must never tunnel through a brick" — maxStep 3px vs brick min dimension 26 → safe. Also vs brick gap: could the ball pass diagonally through the 8px gap without touching? It would touch the side faces. Fine.

Also paddle tunneling: paddle height 16 > 3. Safe.

Now let's also handle the case where the ball is moving up and hits the bottom face of a brick: normal points down → vy = +|vy| → ball goes back down. Good.

Let me write clampDirection to also prevent the ball from being too horizontal overall.

Now writing render.

drawBackground:
```
ctx.fillStyle = '#0d1224'; fillRect(0,0,W,H)
// subtle vertical gradient
const g = ctx.createLinearGradient(0,0,0,H); g.addColorStop(0,'#141a33'); g.addColorStop(1,'#080b18'); 
// grid lines
ctx.strokeStyle='rgba(120,150,255,0.06)'; for x every 40 ...
// border glow
ctx.strokeStyle='rgba(120,180,255,0.35)'; lineWidth 2; strokeRect(1,1,W-2,H-2)
```

drawBricks: for each alive brick: rounded rect with fill gradient, top highlight line, border, and if damaged (hits < maxHits) draw cracks (a few lines) and darken with rgba(0,0,0,0.28) overlay. Flash: white overlay alpha = flash*0.7.

Also draw a subtle shadow beneath.

drawPaddle: rounded rect, gradient from #dfe7ff to #9fb0d8, with a top highlight and a colored core line. Add glow shadow.

drawBall: trail first (circles with alpha), then glow radial gradient, then white ball with slight gradient.

drawParticles: squares/circles with alpha.

drawHUD: score text (monospace), lives as hearts drawn with canvas paths, remaining bricks count.

Overlays: 
- 'ready': text "Press SPACE or click to launch" centered lower area, pulsing alpha.
- 'paused': dim overlay + "PAUSED" + hint.
- 'won': dim + "YOU WIN" + score + "Press R / click to restart".
- 'lost': "GAME OVER".

Text drawing with ctx.font = '600 28px ui-monospace, monospace'.

Heart drawing: path with bezier.

Let me write a helper drawHeart(x,y,s,color).

Now DOM controls section: list of controls, restart button, sound button, and maybe a note.

Let me write the files now.

One more: "Score and lives are visible during play" — canvas HUD. Also maybe mirror in DOM. I'll keep canvas only (graphics via canvas API) but also add DOM status? Not needed. Keep canvas.

Let me write index.html.

```html
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>Breakout</title>
<style>
  :root { color-scheme: dark; }
  * { box-sizing: border-box; }
  html,body { margin:0; padding:0; background:#07090f; color:#e8ecf7; }
  body { font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, "Liberation Mono", monospace; display:flex; justify-content:center; padding:24px 16px 40px; min-height:100vh; }
  .wrap { width:960px; max-width:100%; }
  header { display:flex; align-items:baseline; gap:14px; margin-bottom:14px; }
  h1 { font-size:20px; letter-spacing:.28em; text-transform:uppercase; margin:0; font-weight:700; color:#cdd7ff;}
  .sub { font-size:12px; color:#7b86a8; letter-spacing:.12em;}
  .stage { position:relative; width:960px; max-width:100%; }
  canvas { display:block; width:960px; height:600px; max-width:100%; height:auto; border-radius:10px; background:#0d1224; box-shadow: 0 20px 60px rgba(0,0,0,.6), 0 0 0 1px rgba(120,160,255,.18); cursor: none? }
```
Hmm cursor: none over canvas would hide the cursor — but the paddle follows the cursor; hiding the cursor and showing the paddle is nice. But risky if the user gets lost. I'll use `cursor: crosshair`.

Responsive: canvas max-width 100%, height auto — but then the CSS pixel mapping via rect ratio handles scaling. Good, my pointer mapping uses rect ratio.

Controls panel: grid of kbd + description. Buttons.

Let me write it.

Now write game.js fully. I'll be careful with completeness.

Let me draft the code.

```js
(function () {
  'use strict';

  /* ------------------------------------------------------------------ *
   * Constants
   * ------------------------------------------------------------------ */
  const W = 960, H = 600;

  const COLS = 8, ROWS = 5;
  const SIDE_PAD = 56;
  const BRICK_GAP = 8;
  const BRICK_TOP = 74;
  const BRICK_H = 26;
  const BRICK_W = (W - SIDE_PAD * 2 - BRICK_GAP * (COLS - 1)) / COLS; // 99

  const PADDLE_W = 112, PADDLE_H = 16, PADDLE_Y = 548;
  const PADDLE_SPEED = 900;      // arrow keys, px/s
  const BALL_R = 8;

  const BASE_SPEED = 360, SPEED_PER_BRICK = 8, MAX_SPEED = 760;
  const MAX_BOUNCE_ANGLE = 62 * Math.PI / 180;
  const SUBSTEP_PX = 3;
  const MAX_DT = 1 / 20;

  const ROWS_DEF = [
    { hits: 2, fill: '#ff5f6d', light: '#ffb0b8', dark: '#8e1f2c' },
    { hits: 2, fill: '#ff9f43', light: '#ffd0a0', dark: '#93501a' },
    { hits: 1, fill: '#ffd93d', light: '#fff2ae', dark: '#8f7410' },
    { hits: 1, fill: '#5ce0a5', light: '#b6f5d7', dark: '#1c7a52' },
    { hits: 1, fill: '#5aa9ff', light: '#b9d9ff', dark: '#1a5a99' }
  ];
```

State variables.

Let me write the whole thing in one go and then review.

For particles I'll use a pool array.

Let me write out the code text.

Also: `document.activeElement` — canvas tabindex so keyboard focus works; but I'll attach key listeners to window, so no focus needed. Prevent default for space/arrows to stop page scroll.

Careful: if the user clicks the Restart button and then presses Space, the button would be re-triggered (space activates a focused button). To avoid, call `btn.blur()` after click, and in keydown handler, if e.target is a button, blur it. I'll handle: in keydown, `if (e.target instanceof HTMLButtonElement) e.target.blur();` then preventDefault for space.

Now write.

For the win check: after destroying a brick, if destroyedCount === total → state 'won', sfx.win().

loseLife(): lives--; shake 14; sfx.lifeLost(); if lives<=0 → state 'lost' else state 'ready' + resetBall().

resetBall(): ball stuck to paddle: ball.stuck = true; position at paddle center.

launch(): if state==='ready' → stuck=false; state='playing'; angle random; sfx.launch().

Also on 'ready' the ball should follow the paddle.

Let me write render for 'ready' state: draw a small dashed aim line from ball upward showing launch direction? The launch angle is random, so a fixed vertical hint line is misleading. I'll draw a subtle pulsing ring around the ball instead.

Now, code.

I also want a combo? Not required. Skip.

Let me write the file.

Regarding trail: push {x,y} every substep would be many entries per frame; instead push once per frame in updateBall after the loop, plus keep max 20. At 144Hz, trail of 20 frames = 0.14s; at 60Hz = 0.33s. Slight frame-rate dependence in appearance only — acceptable. Better: push based on distance traveled: accumulate distance and push every 6px, cap 22 entries. That's frame-rate independent. Let's do that.

Trail rendering: for i, alpha = (i+1)/n * 0.35, radius = R * (0.35 + 0.6*(i+1)/n). Draw with color '#8fd0ff'.

Particles: spawn count on destroy: 14; on hit: 5.

Particle update: p.vx *= drag? Add slight gravity 400 px/s². life -= dt. alpha = life/maxLife.

Screen shake: addShake(v) → shake = Math.min(18, shake + v).

Render shake offsets: sx = (Math.random()*2-1)*shake, sy likewise.

Sound functions — write carefully:

```js
function tone(opt) {
  if (!audioCtx || muted) return;
  const t0 = audioCtx.currentTime + (opt.delay || 0);
  const osc = audioCtx.createOscillator();
  const g = audioCtx.createGain();
  osc.type

Empty. Let's write index.html.

Now game.js in chunks.

Chunk 1: constants, state, canvas, audio, input, reset, physics.

Now part 2: rendering, HUD, overlays, main loop.

Note: in `loseLife` when lives <= 0, state='lost' and ball.stuck=true. In update, for 'lost' state we don't draw the ball? I'll draw the ball only when state is ready/playing/paused/won. For 'lost', skip ball.

Also `banner` timer decays.

Let me write rendering.

Also need `update(dt)`:
```js
function update(dt){
  time += dt;
  if (banner > 0) banner -= dt;
  // flash decay always
  for (b of bricks) if (b.flash>0) b.flash = Math.max(0, b.flash - dt*3.2);
  if (state === 'paused') return;
  updatePaddle(dt);
  if (state === 'ready') { ball.x = paddle.x; ball.y = PADDLE_Y - BALL_R; }
  else if (state === 'playing') updateBall(dt);
  updateParticles(dt);
  shake *= Math.exp(-dt*7); if (shake < 0.05) shake = 0;
}
```
Wait — brick flash decay should probably freeze during pause; minor. I'll decay only when not paused. Actually decay always is fine but pause should freeze. Let me freeze on pause (return early before decay except shake?). Simpler: return early on pause for everything except time.

Particles update:
```js
function updateParticles(dt){
  for (let i=particles.length-1;i>=0;i--){
    const p = particles[i];
    p.life -= dt;
    if (p.life<=0){ particles.splice(i,1); continue; }
    p.vy += 520*dt;
    p.x += p.vx*dt; p.y += p.vy*dt;
  }
}
```

Rendering functions. Let me write.

drawField background:
```js
function drawField(){
  // outer
  ctx.fillStyle = '#0b1020'; ctx.fillRect(0,0,W,H);
  // inner play area
  const g = ctx.createLinearGradient(0, CEIL, 0, FLOOR);
  g.addColorStop(0,'#141d3a'); g.addColorStop(1,'#0a1124');
  roundRect(WALL_L-4, CEIL-4, (WALL_R-WALL_L)+8, (FLOOR-CEIL)+8, 10);
  ctx.fillStyle = g; ctx.fill();
  // grid
  ctx.save(); ctx.clip();  // clip to the rounded rect path? path is consumed by fill; need re-create path for clip
```
Better: create path, fill, then re-create path for clip. Or just draw grid lines within bounds without clipping.

Grid: vertical lines every 40 from WALL_L to WALL_R, horizontal every 40.

Then border stroke with glow:
```js
ctx.save();
ctx.strokeStyle = 'rgba(120,170,255,0.35)';
ctx.lineWidth = 2;
roundRect(...); ctx.stroke();
ctx.shadowColor = 'rgba(90,150,255,0.5)'; ctx.shadowBlur = 12; ... 
```
Keep it simple: stroke twice with different alphas.

Also draw a floor line marker (danger zone) — a dashed red line at FLOOR.

HUD:
top strip: SCORE label + value at left; lives hearts at right; "BRICKS n" center.

Let me write text helper.

Overlays: dim rect over the play area with text.

Main loop.

Also draw the "ready" hint text near the paddle.

Let me write part 2 now.

For the win/lose overlay, also show final score and restart hint.

Also draw banner text (LIFE LOST etc.) fading.

Let me write.

One more thing: `roundRect` name conflicts with ctx.roundRect? It's a local function, fine.

Trail drawing: only when playing/paused.

Ball glow: radial gradient.

Let me write the code.

Also, the paddle should show a subtle marker at center for aiming.

Write it.

The edits array got mangled — there's a stray `\ ` in the text ("ctx.fill();\    }") which broke JSON parsing. Let me write part 2 to a separate temp file and concatenate, or just use write with the full file? Better approach: write part2 to a temp file and then use bash to concatenate. Actually simplest: write part 2 content into a file `part2.tmp.js` via write tool, then use bash to replace the placeholder.

Let me do: write part2 to /tmp/part2.js, then bash: head -n -1 game.js > tmp (removing last line `})();`), cat part2 >> game.js. Actually the placeholder is `/* __PART2__ */\n})();`. I'll use python or sed.

Let me write part2 file carefully.

Now splice: remove the last two lines of game.js (`/* __PART2__ */` and `})();`) and append part2.

game.js ends with:
```
/* __PART2__ */
})();
```
So remove the `/* __PART2__ */` line and the `})();` line, then append .part2.js (which ends with `})();`).

Use grep -n to find the placeholder line.

Wait, wc -l says 475 lines but grep says placeholder at 474. So line 474 = `/* __PART2__ */`, line 475 = `})();`. Good.

Splice: head -n 473 game.js > tmp; cat .part2.js >> tmp; mv.

Syntax is valid. Now let me review the whole file carefully for logic issues, and also run a headless simulation test of the physics to verify no tunneling/escaping and that the game is completable.

Let me read the file back.

One issue: keydown 'r'/'R'/'Enter' → restart() even during play. That's fine (R = restart documented). But pressing Enter during play also restarts — acceptable? Enter isn't documented as a control. It's fine but could surprise. I'll keep Enter only for game-over states. Let me adjust: `else if (k === 'r' || k === 'R') { restart(); } else if (k === 'Enter') { if (state==='paused') resume(); else if (state==='won'||state==='lost') restart(); }`.

Also: keydown for 'p' when state is won/lost → togglePause does nothing (pause only from playing/ready). Good.

Another issue: window blur pauses the game. When the user clicks the Restart button, the button gets focus... window blur isn't triggered by that. Fine.

Potential issue: `window.addEventListener('blur', ...)` fires when the canvas or window loses focus. Fine.

Another: after `restart()` from a 'lost' state via keydown space, state = 'ready'. Good.

Issue: in `loseLife` when lives hit 0, we set state='lost' and ball.stuck=true. Then `resume()` from paused would set state='ready' — but state is 'lost', not paused, so pause() won't apply. Good.

Now let me check the physics section and the rest.

Issues found:

1. **`updateBall` guard loop**: `while (remaining > 1e-6 && guard++ < 400 && state === 'playing')`. If state changes to 'won' mid-loop, we break. Good.

2. **Trail push**: `trailDist += s * step` where s is speed before the step. Fine.

3. **Paddle collision when the ball hits the paddle's side while moving down**: `hit.ny < -0.4` check — if the ball hits the top-left corner region, ny might be -0.7 → treated as top face. Fine.

4. **Paddle side collision when ball is beside the paddle and moving down**: hit.ny could be 0 (side) → side reflect. Fine.

5. **Potential problem**: `if (ball.vy > 0 && paddleCollision()) return;` — the `return` skips brickCollisions in that substep, which is fine (paddle is far from bricks).

6. **Ball resting on paddle in 'ready' state**: handled in update().

7. **A subtle bug**: in `stepMove`, after a brick collision the ball may be pushed below FLOOR? No, bricks are at the top.

8. **A real concern**: the ball can be pushed by `clampDirection` into a wall overlap. The safety net clamps x. Fine.

9. **Ball stuck inside a brick scenario**: after resolution, the ball is pushed out by pen+0.6 along the normal. Then clampDirection may rotate the velocity but not the position. Next substep, the ball moves away. Good.

10. **Corner case**: If the ball hits a brick exactly at the corner between two bricks and gets pushed into the neighbor, the neighbor gets hit next substep. Acceptable.

11. **`hitBrick` when destroyed >= TOTAL_BRICKS** sets state='won'. But `brickCollisions` returns true and `stepMove` returns; the updateBall loop exits due to state check. Good.

12. **Score for 2-hit bricks**: 10 + 10 + 50 = 70. Max score = 20*70 + 20*60 = 1400+1200 = 2600. padStart(5) fine.

13. **Enter key restarts during play** — I'll fix so Enter only restarts on game over.

14. **`pause()` on blur while state==='ready'** → paused; resume sets state based on ball.stuck → 'ready'. Good.

15. **Missing**: `window.addEventListener('blur')` fires when clicking outside... fine.

16. **Trail when state is 'won'**: trail remains drawn. Fine.

17. **`drawBall` when state==='lost'** returns early — good.

18. **HUD "the ball got past you N times"** — 3 - lives. On loss lives=0 → 3 times. Good.

19. **Potential issue with `paddle.vx * 0.18` added to vx then normalizeSpeed** — fine.

20. **`launch()` angle ±0.45 rad = ±25.8°.** Good.

21. **Frame-rate independence**: substep loop uses dt; total movement = speed*dt regardless of frame rate. Good.

22. One more: `MAX_DT = 1/20` means on a slow frame the game slows down in real time (no catch-up). That's standard and prevents tunneling. Fine.

23. **`setupCanvas()` called every frame** — cheap due to early return.

24. **`ctx.setTransform(dpr,...)` then clearRect(0,0,W,H)** — correct since transform scales.

25. In render, shake applies to world but HUD is drawn after resetting transform. Good.

Now, a real gameplay concern: **the ball can get into a state where it bounces between the ceiling and the paddle forever without hitting bricks** — that's fine, player moves the paddle.

Another concern: **ball trapped in the gap between two bricks** — discussed; it climbs because |vy| >= 0.3*speed.

Another: **the ball hitting the side of the brick wall region** — bricks start at x=56, walls at 14. Fine.

Let me now write a headless simulation test to verify: no tunneling, no escapes, game completable, and frame-rate independence (compare total distance traveled at 60Hz vs 144Hz).

I'll extract the physics into a test harness. Simplest approach: create a test HTML/JS? Node can't run canvas. Instead, I'll write a node test that re-implements... no, that tests different code.

Better: make game.js testable by extracting the physics core? That complicates the deliverable.

Alternative: run the actual game.js in Node with a stubbed DOM/canvas. I can create a small harness that defines global `document`, `window`, `canvas` with a no-op ctx, `requestAnimationFrame`, `performance`, then load game.js and drive frames manually. But game.js is an IIFE with no exports — I can't access internals.

Trick: I can load the file text, strip the IIFE wrapper, and eval it in a context where I capture internals. E.g., append a line exposing internals. Simpler: in the test harness, read game.js, replace `restart();\n  requestAnimationFrame(frame);` at the end with a test driver that calls the internal functions. Since it's inside the IIFE scope, I can append test code before the closing `})();`.

Let me do that: create test.js that reads game.js, inserts a test hook before the final `})();`, and evals it. The hook can use the internal functions (update, render, launch, state, ball, bricks, etc.) and expose them via a global.

Plan for the harness:
- Stub window/document/canvas/ctx/requestAnimationFrame/performance.
- Provide `document.getElementById` returning fake elements with addEventListener capturing handlers, and getContext returning a recording no-op ctx (all methods no-ops, createLinearGradient etc. returning objects with addColorStop).
- Then simulate: call the captured keydown handler to launch, then step frames at fixed dt for N frames, checking invariants each frame:
  - ball within [WALL_L+R - eps, WALL_R-R + eps] and y >= CEIL+R - eps, and y <= FLOOR + R + something (until lost).
  - ball never overlaps any alive brick by more than a tiny epsilon (no sticking/tunneling).
  - count destroyed bricks; with a "perfect" paddle that tracks the ball x (cheat: set paddle.target = ball.x each frame), the game should be completable → state 'won'.
- Also test frame-rate independence: run the same deterministic scenario (with Math.random seeded? Math.random used in launch angle and particles). I can override Math.random with a seeded PRNG for determinism. Then compare ball position after the same simulated elapsed time at 60Hz vs 144Hz — should be close.

Let me build this test.

For the ctx stub, I need methods used: fillRect, clearRect, beginPath, moveTo, lineTo, arcTo, closePath, fill, stroke, arc, save, restore, clip, setLineDash, setTransform, createLinearGradient, createRadialGradient, fillText, and properties fillStyle, strokeStyle, lineWidth, font, textAlign, textBaseline, globalAlpha, shadowColor, shadowBlur.

I'll use a Proxy for the ctx to auto-stub any method. That's easiest: 
```js
const ctxStub = new Proxy({}, { get: (t,p) => { if (p in t) return t[p]; return (...a)=>gradientStub; }, set: (t,p,v)=>{t[p]=v; return true;} });
```
But properties like fillStyle get would return a function... I need to distinguish. Use a target object pre-populated with known property names set to strings. Simpler: implement an explicit stub object with all needed methods. Let me just write it explicitly — safer.

Also `canvas.getBoundingClientRect`, `addEventListener`, `style`, `width`, `height`.

window: addEventListener capturing handlers, devicePixelRatio, AudioContext undefined (so ensureAudio returns early — good, avoids audio in tests).

document: getElementById returning stub with addEventListener/textContent, addEventListener, hidden=false.

performance.now — Node has global performance.

requestAnimationFrame: I'll capture the callback and drive it manually.

Let me write the harness.

Also need `Set`, `Math` — fine.

Let me write test.js.

For the "perfect paddle" autopilot: after each update, set paddle.target = ball.x (clamped). But paddle.x lerps. To make it truly track, set paddle.x directly too. I'll do: paddle.target = ball.x; paddle.x = ball.x (clamped). But paddle.x clamped to [PADDLE_MIN, PADDLE_MAX]; if the ball is near a wall, the paddle can't reach the ball exactly — fine, it'll still be under it mostly.

Hmm, but with the paddle centered on the ball, the ball always hits the paddle center → rel ≈ 0 → vertical bounce → the ball goes straight up and comes back down the same column, clearing one column only. It would eventually clear... Actually with rel≈0 the ball bounces nearly vertically, hitting bricks in that column, then falls back through the hole. It might never clear other columns. But paddle.vx adds spin (we set paddle.x directly so paddle.vx computed in updatePaddle... if I set paddle.x after update, then next updatePaddle computes prev = that x, so vx ≈ 0).

To make the test complete the game, I'll add a small offset: paddle.target = ball.x + something to give rel offset, e.g., set paddle.x = ball.x - 30 so the ball hits at rel = -30/56 = -0.54 → angle -33°, giving horizontal travel. Let's use a simple AI: paddle.x = ball.x - 0.45*(PADDLE_W/2)*sign(ball.vx)... Let's just do paddle.x = ball.x - 25*sign(ball.vx || 1). Hmm, simpler: paddle.x = ball.x - 28. That gives a consistent leftward deflection, so the ball drifts left, hits the left wall, and sweeps. Over time it should clear most bricks. Let's just try and see the destroyed count.

Alternatively, run many randomized trials and check that at least some reach 'won' — proving completability. And separately check invariants across all trials.

Let me write the test and iterate.

Also test: no brick overlap after each frame (ball not stuck inside a brick).

Let me write it.

Note: game.js uses `window.addEventListener('blur'...)` etc. My stub must accept those.

Also `document.addEventListener('visibilitychange')`.

Also `document.getElementById('restart').addEventListener`, `getElementById('sound')` with `.textContent` settable.

Let me write test.js now.

For determinism, override Math.random with a seeded LCG inside the sandbox.

Implementation: read game.js source, insert before the final `})();` a line: `globalThis.__hook = { get state(){return state;}, set state(v){state=v;}, ... }`. Simpler: expose an object with functions:

```js
  globalThis.__T = {
    restart, launch, update, frame,
    get ball(){return ball;}, get paddle(){return paddle;}, get bricks(){return bricks;},
    get state(){return state;}, set state(v){state=v;},
    get score(){return score;}, set score(v){score=v;},
    get lives(){return lives;}, get destroyed(){return destroyed;}, get speed(){return speed;},
    get keys(){return keys;}, get trail(){return trail;}, get particles(){return particles;},
    consts: { W, H, WALL_L, WALL_R, CEIL, FLOOR, BALL_R, PADDLE_W, PADDLE_MIN, PADDLE_MAX, PADDLE_Y, TOTAL_BRICKS }
  };
```

But `frame` uses `last` and requestAnimationFrame. I'll instead call `update(dt)` directly and skip render (render needs ctx stub anyway; I'll stub it so I can also verify render doesn't throw — good idea to call render too, to catch canvas API errors).

I'll insert the hook right before `restart();\n  requestAnimationFrame(frame);` — actually after restart() so state is initialized. Insert before `})();`.

Let me write the harness with `vm` module or just `new Function`? Use `vm.runInNewContext(src, sandbox)`.

Sandbox globals: window, document, performance, requestAnimationFrame, Math, Set, Math.random override, globalThis → in vm, `globalThis` refers to the context's global. Setting `globalThis.__T` works.

Let me write it.

Careful: game.js references `window.devicePixelRatio`, `window.AudioContext` (undefined → ensureAudio returns). Good.

Let me write the file.

Note: the hook references `T.speed` getter — I included `get speed(){return speed;}`. Good. But `T.speed = speed` in tunnelTest — there's no setter for speed. I'll remove that line or add a setter. Let me add a setter for speed in the hook. Actually I wrote `T.speed = speed;` in tunnelTest — with only a getter, assignment in non-strict vm context silently fails (the vm context code is non-strict? game.js is strict but the test file is separate). It would just be ignored... Actually assigning to an object with only a getter throws in strict mode; the test file isn't strict, so it silently fails. But then the ball speed would be reset by normalizeSpeed to the real speed anyway. Let me add a setter to the hook to make the tunnel test meaningful.

Let me update the hook to include `set speed(v){speed=v;}`.

Also `T.ball.vx = 0; T.ball.vy = -speed;` — then update() calls updateBall which uses hypot for substeps, and normalizeSpeed is only called on collisions. So the ball travels at `speed` until it hits something. Good.

Also in checkInvariants, `Math.abs(sp - T.speed) > 1e-6` — after a wall bounce normalizeSpeed keeps magnitude. But between collisions, magnitude stays constant. OK. However, after `launch()` with random angle, vx²+vy² = speed² exactly. Good.

But careful: in the fps test I set ball.vx=0, vy=-T.speed → magnitude = speed. Good.

In the tunnel test, I set vy=-speed where speed param may exceed T.speed (760 or 1500). With the setter, T.speed = speed. But `hitBrick` recomputes speed = min(MAX_SPEED, ...) after each destroy → speed drops back to ≤760. That's fine but then normalizeSpeed would reduce the ball's speed to 760. Still tests tunneling at 760+. For 1500, the first substep test: SUBSTEP_PX=3 → step = 3/1500 = 2ms; per 1/60s frame → 20 substeps of 3px. Good.

Let me add the setter and run.

Also `checkInvariants` requires `Math.abs(ball.vy) >= 0.29*speed` when playing — after tunnel test sets vy=-1500 and speed=1500, fine.

Hmm, but in the tunnel test after the first brick destroy, speed becomes min(760, 360+8) = 368, and normalizeSpeed is applied at the bounce → ball speed 368. Fine.

Another thing: `T.launch()` sets state='playing' and gives a random velocity; then I override vx/vy. Fine.

Also in playRun, `while (T.state === 'playing' || T.state === 'ready')` — after restart state is 'ready', then launch. Fine.

Let me add the speed setter and run the test.

Also fix the Enter-key restart-during-play issue in game.js first? Let me run tests first.

There's a parent package.json with type: module. Rename test to .test.cjs. Note: game.js is loaded via vm so it's unaffected by package.json. Good.

Also important: the parent package.json "type":"module" doesn't affect browser loading of game.js. Fine.

Rename to .test.cjs.

Great news: the game is completable (12/12 AI wins, max score 2560), lazy AI loses, no escape/tunnel failures reported other than "speed drift".

The "speed drift" is a real (minor) gameplay issue: when a brick is destroyed, `speed` increases but the ball's velocity magnitude isn't renormalized to the new speed until the *next* collision... wait, actually normalizeSpeed() is called BEFORE hitBrick in brickCollisions. So after the speed increase, the ball keeps the old magnitude until the next bounce. That means the speed increase only applies at the next bounce. That's acceptable behavior, but let's make it immediate and consistent: call normalizeSpeed() after hitBrick too. Let me restructure: in brickCollisions, do the reflection, then hitBrick (which may raise `speed`), then normalizeSpeed/clampDirection/normalizeSpeed. That makes speed changes immediate.

Also the paddle bounce: normalizeSpeed after paddleCollision uses the current speed — fine.

Wall bounces: normalizeSpeed uses current speed — if speed increased earlier and the ball kept the old magnitude, the wall bounce would snap it to the new speed. So the drift is transient. Let me fix by renormalizing after hitBrick.

Also the fps test: travelled differs — 2065 (60Hz) vs 2362 (240Hz). That's a 14% difference. Why? Because "travelled" is measured as the sum of per-frame position deltas, which underestimates when the ball bounces within a frame (the delta is the chord, not the path length). At higher fps, fewer bounces per frame → less chord shortening. So the measurement is biased, not the actual speed. Better test: measure the ball's position after a fixed simulated time in a scenario without collisions, or measure speed magnitude directly.

Better test: disable collisions by using a scenario where the ball just flies? Hard. Alternative: measure `Math.hypot(vx,vy)` — should equal speed at all times. And measure the total path length accounting for substeps... 

Simplest robust test: place the ball in an empty region far from bricks and paddle, give it a velocity, and integrate for a fixed simulated time with different dt, then compare the final position (with wall bounces it's messy). Let's instead measure the accumulated distance using the actual velocity * dt: sum over frames of speed*dt should equal speed*totalTime exactly for all fps. That verifies time scaling. Plus a separate check: final position after N seconds of bouncing should be identical across fps (within tolerance) — that tests determinism of the collision handling.

Let me redo: 
- test A: sum(speed_i * dt_i) == speed * 10 for each fps (exact).
- test B: final ball position after 10s of bouncing off walls only (no bricks? bricks are in the way). I could move the ball below the bricks: set ball.y = 400, vy = -speed... it will hit bricks. Instead, kill all bricks (set alive=false) and disable the paddle by setting state... hmm, the paddle is at 540 and the ball would hit it. I can set paddle.x far away (e.g., at PADDLE_MIN) and start the ball at x=900. Then the ball bounces off walls/ceiling/floor... floor → lose life. 

Alternative: run with only wall+ceiling bounces: start ball at y=300 moving up, x=900, paddle at far left. It bounces ceiling/walls and eventually falls to the floor → life lost. Over 10s it will lose lives. Not great.

Simplest: compare the ball's trajectory over a short window (e.g., 2 seconds) where it only bounces off walls/ceiling, starting from the middle. Compute final position across fps and compare with tolerance ~2px. Let's do: clear all bricks (alive=false), paddle parked at PADDLE_MIN, ball at x=900, y=400, vy=-speed, vx=+speed*0.5. Over 2s at speed 360: travels 720px. It will bounce off walls/ceiling but should not reach the paddle (paddle spans x 70..182; ball starts at x=900 moving right, bounces back...). Risky. Let me just cap the test at 1.2s and check the final position tolerance.

Actually a cleaner determinism test: count destroyed bricks and final position after a fixed number of simulated seconds with the tracking AI. Already done: destroyed matched across fps (3 for all). And final y=532, x=480 for all — wait, that's the fps test with paddle parked at 480 and the ball launched straight up at x=480 → it hits bricks, bounces back down onto the paddle at 480, bounces straight up again. Final y=532 x=480 for all four fps — identical! That's a strong determinism result. 

So the only "failure" was my flawed travelled-distance metric. Let me replace it with: sum(speed*dt) exactness + final position equality.

Let me also verify the ball's speed magnitude equals `speed` at all times after the fix.

Now let me fix the speed renormalization in game.js, and also fix the Enter key.

Changes to game.js:
1. In brickCollisions: move normalizeSpeed/clampDirection after hitBrick.
2. Enter key handling.

Let me apply.

For brickCollisions ordering: reflect → hitBrick (may change speed) → normalizeSpeed → clampDirection → normalizeSpeed. But hitBrick may set state='won'; that's fine.

Also the contact point for particles uses ball.x - nx*R computed after push-out; hitBrick is called with those coords. Keep computing contact before hitBrick.

Let me rewrite the block:

```js
      ball.x += hit.nx * (hit.pen + 0.6);
      ball.y += hit.ny * (hit.pen + 0.6);
      const dot = ball.vx * hit.nx + ball.vy * hit.ny;
      if (dot < 0) {
        ball.vx -= 2 * dot * hit.nx;
        ball.vy -= 2 * dot * hit.ny;
      }
      const cx = ball.x - hit.nx * BALL_R, cy = ball.y - hit.ny * BALL_R;
      hitBrick(b, cx, cy);
      normalizeSpeed();
      clampDirection();
      normalizeSpeed();
      return true;
```

Also for the paddle: `ball.vx = Math.sin(ang)*speed + paddle.vx*0.18;` then normalize. Fine.

Now update the test metric.

Now fix the fps test metric. Replace distanceAt with a proper test:

```js
function fpsTest(fps, seed) {
  const { T } = load(seed);
  T.restart(); T.launch();
  T.ball.vx = 0; T.ball.vy = -T.speed;
  T.paddle.target = T.paddle.x = 480;
  const dt = 1/fps;
  const n = Math.round(10*fps);
  let integrated = 0;
  for (let i=0;i<n;i++){
    T.update(dt);
    integrated += Math.hypot(T.ball.vx, T.ball.vy)*dt;
    checkInvariants(T, ...);
  }
  return { integrated, x:T.ball.x, y:T.ball.y, destroyed:T.destroyed, speed:T.speed };
}
```
integrated should equal ~speed*10 for all fps (speed grows as bricks are destroyed, so it's speed-dependent; compare across fps: should match closely since destroyed counts match).

Also add a pure time-scaling test: park the ball in a brick-free zone... Let me add a test where all bricks are removed (alive=false) and the paddle is parked far away, and the ball bounces only off walls/ceiling for a short window; compare final position across fps.

Setup: T.restart(); T.launch(); then set all bricks alive=false; place ball at x=480,y=300, vx = speed*0.6, vy=-speed*0.8 (magnitude speed). Park paddle at PADDLE_MIN (x=70). Ball at x=480 moving right/up. Over 1.5s at speed 360 → 540px path. Will it reach the paddle? Paddle spans 14+... PADDLE_MIN = 14+56 = 70 → paddle spans x 14..126. Ball starts at 480 moving right: hits right wall at 932-8=924, comes back left. Vertical: starts y=300 moving up at 0.8*360=288 px/s → reaches ceiling (y=62) in 0.83s, comes back down. After 1.5s, y = ? It'd be back down around y=300+... Let's compute: up 238px in 0.83s, then down 0.67s*288 = 193px → y ≈ 62+193 = 255. Not near the paddle (540). Good, 1.5s is safe. Let me use 1.5s and compare final positions across fps with tolerance 1px.

Let me rewrite that section of the test.

Also the tunnel test: `T.speed = speed;` then `T.ball.vy = -speed;` — order matters; I set vx/vy before T.speed. Since normalizeSpeed is called on collision using `speed`, setting T.speed first is better. Let me reorder in the test. Also add a tunnel test that aims at the *gap* between bricks and at corners, and a test with huge dt (e.g., 1/5 s frames) to ensure no tunneling with big frames.

Let me also add a test: run with dt = 1/10 (slow frames) and check invariants + completability.

Let me update the tunnel test section.

Note: in the slow test, MAX_DT = 1/20 clamps dt, so at 8Hz and 12Hz the game runs in slow motion (dt clamped to 0.05). That's intentional. The invariant check still applies.

Also `checkInvariants` requires speed magnitude == T.speed exactly. In the slow test after launch, magnitude = speed. OK.

Run.

Progress. Remaining issues:

1. **"ball inside brick d=6.38"** at fps60 f47 and fps30 f23 — the ball is 6.38 from the closest point of a brick (radius 8), i.e., 1.62px penetration, exceeding my 1.2 tolerance. This happens right after a collision: the ball hits brick A, gets pushed out, then... hmm. Actually the sequence: the ball collides with brick A (index i), gets pushed out. But then in the *same* substep we return. Next substep, the ball moves 3px and may now overlap brick B (a neighbor) — that's normal pre-collision overlap which is then resolved. My invariant checks after the whole frame (after update returns), so the ball may end a frame slightly overlapping a brick it's about to bounce off in the next substep... no wait, the loop continues until `remaining` is exhausted, so at the end of updateBall the last substep resolved any overlap. Hmm, but the resolution pushes out by pen+0.6, so d >= 8 - ... let me think.

Actually the overlap can occur when the ball ends a frame overlapping a brick *without* a collision being detected? No — if it overlaps, circleRect returns a hit and it's resolved.

Unless: the collision was resolved against brick A, pushing the ball into brick B (push direction away from A, into B). Then we return from brickCollisions (one brick per substep). If that was the last substep of the frame, the frame ends with the ball overlapping B. Next frame's first substep resolves it. So it's transient overlap of ≤1 substep, not "stuck". My check is too strict for a single frame boundary.

Where does this happen? brick(484,214) is row 4 (y=78+4*34=214), col 4 (x=56+4*107=484). The ball at x=480 moving straight up hits the left edge region of that brick → pushed left → into the gap → then hits the neighbor... Actually pushed left from brick at x=484 → ball at 484-8-0.6 = 475.4. Neighbor brick col3 spans x=377..476. So the ball at 475.4 is inside col3's brick by 0.6px horizontally! d would be ~0.6, not 6.38. Hmm, d=6.38 means the closest point distance is 6.38 → penetration 1.62.

Anyway: transient overlap at a frame boundary. Is it a real problem? The ball is not stuck; it resolves on the next frame. But "the ball must never tunnel through a brick, stick inside one" — a 1.6px overlap for one frame is invisible and self-correcting. Still, I can make it cleaner: in `brickCollisions`, loop until no collisions remain (resolve all overlaps in a substep), with a small iteration cap. Let me restructure: 

```js
function brickCollisions() {
  let resolved = 0;
  for (let pass = 0; pass < 4; pass++) {
    let hitAny = false;
    for (...) { ... if hit { resolve; hitBrick; hitAny = true; break; } }
    if (!hitAny) break;
    resolved++;
  }
  return resolved > 0;
}
```
But multiple brick hits in one substep could cause double-scoring on the same contact — that's fine/realistic (grazing two bricks).

Hmm, but there's a risk: the ball squeezed in an 8px gap gets resolved left then right then left... up to 4 passes, ending still overlapping. Then the next substep continues. Since vy carries it out, it's fine.

Actually a cleaner fix: after resolving a brick hit, don't push *into* the neighbor. The push is along the collision normal, which for a side hit pushes the ball horizontally into the gap. The gap is 8px and the ball radius is 8, so the ball can never fit in the gap — it will always overlap one of the two bricks. That's the root cause: the ball physically cannot be at rest in the gap; it must overlap one brick. So my invariant "ball must not overlap any brick" is unsatisfiable when the ball's center is in a gap.

Wait — is that right? The gap is 8px wide. The ball center at gap center: distance to each brick's face = 4 < 8. So yes, the ball center in the gap always overlaps both bricks. So the invariant is impossible to satisfy in the gap. The physics handles it by pushing out and reflecting, and the ball climbs through.

Hmm, but that produces jitter: the ball alternately bounces off the left and right faces of the gap while climbing, losing horizontal velocity each time (vx flips back and forth). Net effect: the ball passes through the gap vertically while damaging both bricks. Visually it looks like the ball grinding through the gap. Acceptable but not lovely.

Better design: make the gap wider than the ball diameter? BRICK_GAP = 8 → too narrow. If I set BRICK_GAP = 17 (> 2R = 16), the ball can pass through the gap cleanly. Let's check the layout: BRICK_W = (960 - 112 - 7*17)/8 = (960-112-119)/8 = 729/8 = 91.1. Bricks 91x26 with 17px gaps — that looks a bit gappy but fine. Hmm, visually 17px gaps between 91px bricks is chunky.

Alternative: keep the gap at 8 but make the ball radius smaller (R=7 → diameter 14 > 8, still doesn't fit).

Alternative: accept it. Real Breakout games have small gaps and the ball never really enters a gap head-on because it approaches from below and hits the bottom face of a brick first. The gap-entry case only happens when the ball's x lands exactly in an 8px window — rare, and when it happens the ball hits the bottom face of the brick above (the gap is only 8 wide, but the ball is 16 wide, so approaching from below, the closest point on either brick is a corner/face → normal is diagonal → the ball is deflected sideways and up/down. It never really "enters the gap" because it collides with the bottom faces first.

Let me reconsider the failing case: brick(484,214) is the bottom row (row 4). The ball at x=480 moving straight up. Brick col4 spans x=484..575, y=214..240. Ball center at x=480 → 4px left of the brick's left face. Ball center y approaching 240 (bottom face). Closest point = (484, 240) → the bottom-left corner. dx = -4, dy = -? When the ball center is at y=233 (say), closest point clamps y to [214,240] → py = 233, px = 484 → dx=-4, dy=0 → normal (-1, 0) → pure horizontal push left. So the ball gets pushed left and reflects vx — but vx was 0! So nothing changes except a position nudge left. Then it continues up, next substep closest point again (484, y) → pushed left again... The ball slides up along the left face of the brick, being nudged left each substep, and hits the brick to the left (col3 spans 377..476): when the ball center reaches x < 476+8 = 484... it's already at 480 < 484 → overlapping col3's right face by 4px. So the ball is wedged in the gap between col3 (right edge 476) and col4 (left edge 484): center at 480, distance 4 to each face. It's wedged.

Then the collision resolution: iterate bricks in order; col3 comes first (index 3 < 4). circleRect with col3: closest point (476, y) → dx = +4 → normal (+1,0) → push right by (pen+0.6) = (8-4)+0.6 = 4.6 → ball.x = 484.6. Reflect: vx=0, dot=0 → no reflection. normalizeSpeed: vy unchanged (still -speed), vx=0. Then hitBrick(col3) → score, particles. Next substep: ball at x=484.6, overlapping col4 (484..575): closest point (484, y) → dx=+0.6 → normal (+1,0) → push right by 8-0.6+0.6 = 8 → x = 492.6. Reflect vx=0 → nothing. hitBrick(col4). So the ball climbs through the gap, alternately damaging col3 and col4 each substep — scoring a lot and destroying bricks rapidly! That's the "grinding" behavior. With 3px substeps and 26px brick height, it would damage each brick ~9 times per pass... but each brick only needs 1-2 hits, so it destroys both quickly. Not a bug per se, but it's a scoring exploit and looks bad.

Better fix: prevent the ball from entering the gap in the first place by making the collision response handle "wedged" cases: if the ball overlaps two bricks on opposite sides, resolve by pushing along the axis of motion (reverse vy) rather than sideways.

Cleanest robust fix: **widen the gap so the ball can't wedge**. Gap must be > 2R = 16. Let's use BRICK_GAP = 10 and BALL_R = 5? Then diameter 10 = gap exactly — borderline. Use BALL_R = 5, gap 12: diameter 10 < 12 → the ball fits through the gap cleanly. But a 5px radius ball is small on a 960x600 field. Hmm, 10px diameter ball is small but playable. Typical breakout balls are ~10-12px.

Alternative: keep R=8 and gap 17. Bricks 91x26. Actually that's fine visually — chunky retro look. Let me compute: 8 bricks × 91 + 7 × 17 = 728 + 119 = 847 ≈ 848 available. Good.

But wait: with gap 17 > 16, the ball can pass through the gap without touching either brick. But it can still wedge against a single brick's corner. That's handled fine.

Hmm, but there's another consideration: with a 17px gap, the ball can pass between rows? Vertical gap = 17 too (BRICK_H + gap = 43). Fine.

Alternatively, keep the gap small and add anti-wedge logic: in brickCollisions, after resolving, check if the ball still overlaps another brick with an opposing normal; if so, reverse the velocity along that axis (push the ball out along its direction of travel). Complexity.

I think widening the gap is the cleanest, most robust solution. Let me pick gap = 12 and ball radius 6 (diameter 12 = gap → borderline, exactly fits). Use gap = 14, R = 7 (diameter 14 = gap → borderline). Use gap = 16, R = 7 (diameter 14 < 16, 2px clearance). BRICK_W = (960 - 112 - 7*16)/8 = (960-112-112)/8 = 736/8 = 92. Bricks 92x26 with 16px gaps. Ball radius 7.

Hmm, but also the ball must not wedge against the paddle/wall. Wall at x=14, first brick at x=56 → 42px clearance. Fine.

Let me also double check: with gap 16 and R 7, the ball center passing through the gap: to touch neither brick, the center must be within [476+7, 492-7]... wait with gap 16: col3 right edge = 56+3*108+92 = 56+324+92 = 472; col4 left edge = 56+4*108 = 488. Gap = 16 (472..488). Ball center must be in [479, 481] to avoid both — a 2px window. So the ball will still usually touch a brick when crossing the gap line, but it will never be *wedged* (pushed out one side into the other), because the push-out of 8px max moves it clear.

Hmm, is that enough? Consider the ball center at x=485 (3px from col4's left face at 488), overlapping col4 by 4px (8-... let me compute: closest point x=488, dx = 485-488 = -3, d=3 < 7 → normal (-1,0), pen = 7-3 = 4 → push left by 4.6 → x = 480.4. Now distance to col3's right face (472) = 8.4 > 7 → clear! Good, no wedge. Because gap 16 > 2R = 14, pushing out of one brick by pen+0.6 puts the center at least gap - R... let's verify generally: if the center is at distance d < R from the right face of brick A (at x=a) then center x = a - ... hmm, let me redo: brick A right edge at a, brick B left edge at b = a + gap. Center x < a (overlapping A from the left side? no). Let me set: center x in (a, b) (inside the gap region) but overlapping B (whose left edge is b) means b - x < R → x > b - R. Push out of B along normal (-1,0) by (R - (b-x)) + 0.6 → x' = x - (R - b + x) - 0.6 = b - R - 0.6. Distance from A's right edge: x' - a = b - R - 0.6 - a = gap - R - 0.6. For no overlap with A we need x' - a >= R → gap - R - 0.6 >= R → gap >= 2R + 0.6. With gap=16, R=7: 16 >= 14.6 ✓. 

So gap 16 with R 7 guarantees no wedging from horizontal pushes. Similarly for vertical: rows are separated by BRICK_GAP = 16 too, and brick height 26. Vertical pushes: gap >= 2R + 0.6 ✓.

Great — set BRICK_GAP = 16, BALL_R = 7. BRICK_W = (960 - 112 - 112)/8 = 92.

Hmm, but visually 16px gaps with 26px-tall bricks... rows: 78, 120, 162, 204, 246 → bottom 272. Play area 272..540 = 268px. Fine.

Actually, let me reconsider the aesthetics: 92×26 bricks with 16px gaps. That's a fairly airy grid. Alternatively reduce SIDE_PAD to 40: BRICK_W = (960 - 80 - 112)/8 = 768/8 = 96. Bricks 96×26, gaps 16. Better. Let me use SIDE_PAD = 40. Then bricks span 40..920. Wall at 14 → 26px clearance from the left wall to the first brick; the ball (R=7) can travel in that channel. Fine.

Hmm, but wait: could the ball get wedged between the wall and a brick? Wall at x=14, brick left edge at 40. Channel width 26 > 2R=14. Fine.

Let me also double check the vertical: CEIL=54, BRICK_TOP=78 → 24px channel between the ceiling and the top row; ball diameter 14 fits. Good.

Now, another consideration: with gap 16 the "grinding" exploit disappears.

2. **"integrated speed differs across frame rates"**: 1925 (60Hz) vs 2025 (240Hz), 5% difference. Why? Because `integrated += |v| * dt` where |v| = speed. Sum = Σ speed_i * dt_i. The speed changes when bricks are destroyed, and the timing of destructions differs slightly across fps (discrete collision events). Also at 240Hz, dt=1/240; the sum should be speed*10 exactly if speed were constant. With 3 bricks destroyed, speed goes 360→384 at slightly different simulated times → small differences. 5% seems large for that though. Let's compute: if speed changes at time t, integral = 360*t + 384*(10-t). Difference of 100 in the integral → Δt = 100/24 = 4.2s?? That can't be from 3 destroys.

Hmm wait — destroyed=3 for all, speed=384 for all. So the integral difference must come from something else. Let me reconsider: maybe the ball's speed magnitude isn't always equal to `speed` — e.g., during the substep loop, after a brick destroy the speed changes and normalizeSpeed applies immediately (I fixed that). But `integrated` is measured once per frame using the velocity at the END of the frame, so within a frame where speed changed mid-way, the integration is approximate. At 240Hz there are more frames, so finer sampling... but that should make it *more* accurate, not 5% off.

Hold on: maybe the ball lost lives / reset? No, lives=3.

Let me reconsider: is the ball's speed magnitude equal to `speed` at all times? checkInvariants verifies |v| == speed within 1e-6 for state 'playing' — and no speed-drift failures appeared this run. So |v| = speed always.

So Σ speed_i·dt_i where speed_i is the speed at the end of frame i. Total = 10 s. If speed = 360 for most of it and 384 after 3 destroys: 360*10 = 3600. But the measured integral is 1925?! That's way less than 3600. So the ball is NOT moving at `speed` for the whole time... 

Oh! The ball spends time in state 'ready' after losing a life? No, lives=3 unchanged. Hmm, but wait: `distanceAt` calls T.launch() then sets vx=0, vy=-speed. Then update... The ball bounces up, hits bricks, comes back down to the paddle at x=480, bounces up... The paddle collision sets vy = -cos(ang)*speed and vx = sin(ang)*speed + paddle.vx*0.18. paddle.x is fixed at 480 so paddle.vx ≈ 0. rel = (ball.x - 480)/56 ≈ 0 → ang ≈ 0 → vy = -speed. OK.

So why is the integral ~1925 instead of ~3600? Unless... `T.update(dt)` is called n = 10*fps times, but MAX_DT clamps dt to 1/20 — not relevant for 30-240Hz.

Hmm, 1925/10 = 192.5 average speed vs 360-384. So the ball's velocity magnitude is roughly half of what I think... 

OH WAIT. `integrated += Math.hypot(T.ball.vx, T.ball.vy) * dt` — but `T.ball` getter returns the ball object; fine.

Unless the ball is in state 'ready' for part of the time (after losing a life, lives would drop). lives=3 in the output... but `lives` is read at the end. If the ball lost a life and lives=2, the output would show 2. It shows 3.

Hmm, let me just instrument: print the integral per second. Actually, maybe the issue is that `T.launch()` is called, then I set vx/vy — but `launch()` sets state='playing'. Then update runs. Fine.

Let me debug: compute Σ|v|·dt for a single fps with no collisions (wallOnly) — should be speed*1.5 = 540.

Actually hold on, maybe the ball ends up stuck bouncing between the paddle and a brick at low effective speed? No, |v| = speed always per the invariant.

Unless the invariant check `Math.abs(sp - T.speed) > 1e-6` never triggers because... sp is computed from ball.vx/vy. Hmm, it passed.

So Σ speed·dt over 10 s with speed ∈ [360, 384] must be ≈ 3600-3840. Getting 1925 means dt is being halved somewhere... 

OH! I see it. In `updateBall`, the substep loop: `const step = Math.min(remaining, SUBSTEP_PX / Math.max(s, 1));` — with s = 360, SUBSTEP_PX/s = 0.00833 s. remaining = 1/60 = 0.01667. So 2 substeps. Fine, total = remaining. Unless the guard (400) cuts it off — no.

Hmm, but what if `state` changes to 'ready' mid-loop... no.

Wait — maybe the ball IS losing lives and the game restarts? No.

Let me just measure directly rather than speculate. I'll add a debug print of Σ dt and Σ|v|dt and the number of frames.

n = 10*60 = 600 frames, Σdt = 10 s. Σ|v|dt = 1925 → average |v| = 192.5.

Unless... `T.speed` getter returns `speed` = 384 at the end, but during the run speed was 360. And |v| = speed = 360 → Σ = 3600. Contradiction. So |v| must be much smaller than `speed` at times, meaning checkInvariants' speed check isn't catching it... 

AH — I bet the issue is that checkInvariants only checks when `T.state === 'playing'`, and the state might be 'ready' part of the time (ball stuck, v=0). If the ball lost a life, lives would be 2. But the printed lives=3... 

Hmm, unless `lives` printed is from `T.lives` — yes.

OK, let me just debug empirically.

3. **"wall trajectory diverges at 75Hz and 360Hz"** — small divergence (1.4-1.6px). This is because collisions are resolved discretely: the exact time of a wall bounce within a frame differs, so the position after a fixed time differs by up to one frame's travel (360/75 = 4.8px). That's inherent to discrete collision detection, not a speed bug. The *speed* is frame-rate independent (that's the requirement). I'll relax the tolerance to ~ (speed/fps) + 2, or better: compare the trajectory only for collisions-free motion... Actually the divergence at 75Hz is 1.44px and at 360Hz 1.6px — tiny. I'll set the tolerance to 3px and note that bounce-phase quantization is expected. Better: compare the *distance traveled* (which for wall-only motion = speed × time exactly) and the speed vector. vx/vy matched exactly (216, 288) across all fps. That's the real proof of frame-rate independence. I'll assert on the velocity vector and on total path length, and use a loose position tolerance.

4. **"restart did not restore 2-hit rows, hits=56"** — my test computed `hits` as the sum of `x.hits` over ALL bricks (including dead ones, whose hits are 0 after destruction). After restart, all bricks are rebuilt with hits = maxHits → sum should be 16*2 + 24*1 = 56! I mis-computed the expected value as 60. 16*2=32, 24*1=24 → 56. My test expectation was wrong. Fix the test.

Let me fix the test expectations and investigate the integral issue.

Let me write a quick debug script.

The ball lost a life (lives=2, state='ready') — so it sat stuck for the rest of the run, explaining the low integral. My test's `lives` print showed 3 earlier because... in the earlier run it printed lives? No, distanceAt didn't print lives. Right — it printed destroyed and speed only. So the low integral is because the ball died and sat stuck. Not a bug.

So the frame-rate test needs to keep the ball alive: use an AI paddle that tracks the ball. Let me update distanceAt to use the offset AI so the ball stays in play, and compare the integral across fps.

Also note: at frame 360 the ball is at y=532 = PADDLE_Y - BALL_R = 540-8 = 532. Good.

Now let me apply the geometry fix (gap 16, R 7, SIDE_PAD 40) and re-run.

Changes in game.js:
- SIDE_PAD 56 → 40
- BRICK_GAP 8 → 16
- BALL_R 8 → 7
- BRICK_W = (960 - 80 - 7*16)/8 = (960-80-112)/8 = 96

Check brick grid: x from 40 to 40+8*96+7*16 = 40+768+112 = 920. Right edge 920, WALL_R = 946 → 26px channel. Good.

Rows: BRICK_TOP 78, step 26+16 = 42 → 78,120,162,204,246; bottom 272.

Vertical channel between ceiling (54) and top row (78) = 24 > 14. Good.
Channel between last row (272) and paddle (540) = 268. Good.

Also update the comment "8 columns × 5 rows with a gap".

Also `PADDLE_W = 112` fine.

Now, with gap 16 the wedge problem is gone. Let me also re-verify the "ball inside brick" invariant passes.

Also update the test's expected hits sum to 56.

And relax the wall trajectory position tolerance while asserting velocity equality.

Let me make the changes.

Now update the tests: 
1. distanceAt: use AI to keep the ball alive.
2. wall trajectory tolerance: assert velocity equality and loose position.
3. hits sum expectation 56.
4. gap test x positions: with new geometry, gap between col0 (40..136) and col1 (152..248) → gap center 144. Corner test x=40.

Let me update.

Also the `wallOnly` test uses `T.C.PADDLE_MIN` — fine. And the checkInvariants tolerance for brick penetration is `BALL_R - 1.2`; with the new geometry it should hold.

Also `wallOnly` sets ball at x=480,y=300 — with new geometry bricks are alive=false so no bricks. Good.

Run.

All tests pass now. Notes:

- `integrated` = 3600 exactly for all fps → perfect frame-rate independence of speed.
- destroyed=0 in the fps test because the ball launched straight up at x=480 which is now a gap (col boundary)... x=480: bricks col4 spans 40+4*112=488..584; col3 spans 376..472. So 480 is in the gap 472..488 → the ball passes through the gap and never hits a brick, then falls back to the paddle at 480 forever. That's fine (it proves gap passage). But it means the fps test isn't exercising brick collisions. Let me change the launch x to 536 (center of col4) so it hits bricks. Actually the paddle is at 480 and the ball returns to 480... if I set the ball x=536 and the paddle at 536, it would hit bricks. Let me set paddle x = 536 and ball x = 536. Then it bounces straight up into col4. Good — that exercises brick collisions across fps.

Hmm, but with the ball hitting the paddle dead center, rel≈0 → straight up again. It'll destroy col4's 5 bricks (2 of them 2-hit) then fall through the cleared column. destroyed would grow. Fine for the test.

Let me update distanceAt to use x=536 for both ball and paddle.

- "fast into gap @1500: destroyed 0" — the ball passes cleanly through the gap at 1500 px/s without tunneling through a brick (it went up through the gap and hit the ceiling, then fell and lost a life). Good: no brick destroyed, no invariant violation. 

- The tunnel tests end in 'ready' (life lost) because the ball goes straight up and comes straight back down past the parked paddle. Fine.

Let me also add a test that specifically verifies the ball never passes *through* a brick: aim the ball at a brick center at very high speed and check that the brick was hit (destroyed=1) — already shown ("fast straight @1500: destroyed 1"). Good.

Now let me also add a stress test: many random runs with random paddle AI and random dt values, checking invariants over lots of frames. Let me add a randomized fuzz test with random dt between 1/240 and 1/20 and random paddle targets, 20 runs × 3000 frames.

Also I should double check the `won` state can be reached at high speed (MAX_SPEED 760) — the offset AI wins, and speed reaches 760 at the end (360+40*8=680 max actually: 360 + 40*8 = 680). So MAX_SPEED 760 is never reached; the cap is just a safety. Fine — "speed increases gradually with a cap".

Let me add the fuzz test and the brick-hitting fps test, then run.

Also: I should double-check the visual layout numbers by rendering to a PNG? Can't easily without canvas lib. I'll instead verify geometry arithmetic manually:
- BRICK_W = (960 - 80 - 112)/8 = 768/8 = 96 ✓
- last brick right edge = 40 + 7*(96+16) + 96 = 40 + 784 + 96 = 920 ✓ (WALL_R = 946)
- rows bottom = 78 + 4*42 + 26 = 78+168+26 = 272 ✓
- paddle 540..556, FLOOR 566 ✓
- HUD top strip 0..54: score text baseline 44, hearts at cy 36 (extends to ~44.6) ✓
- bottom strip 566..600: hint text baseline 590 ✓

One more: the "PRESS SPACE OR CLICK TO LAUNCH" text at y=470 — inside the play field, fine.

Banner text at y=330 — fine.

Now, let me also consider: the paddle at PADDLE_Y=540 and FLOOR=566; the ball is lost when ball.y - R > 566 → y > 573. The paddle bottom is 556. So the ball can travel 17px below the paddle before dying. Fine.

Let me add the fuzz test.

My placeholder edit was a mistake (I included a bogus edit). Edits 0 and 2 — but the whole call failed. Let me redo with just the two valid edits.

Note edits[0] and edits[2] both target text; edits[2] oldText "/* ---- 6. scoring maths ---- */" is unique. Let me resubmit without the bogus one.

The fuzz test uses `T.keys` — I exposed `get keys(){return keys;}`. Good. And `T.render()` needs the ctx stub — makeCtx is defined in makeSandbox? Actually makeEl returns getContext: () => makeCtx(). Yes.

Run.

Excellent:
- integrated path length identical across 30/60/144/240 Hz (3803.5–3804.0, <0.02% diff) → frame-rate independent.
- destroyed count identical across fps.
- worst brick penetration across 25 fuzz runs with random dt (20–240Hz) = 0.00px → the ball never penetrates a brick at a frame boundary. No escapes.
- Game completable (12/12 AI wins, also at 8Hz and 12Hz), max score 2600? Wait, "max possible score=2560" from my formula: 16*(10+10+50) + 24*(10+50) = 16*70 + 24*60 = 1120 + 1440 = 2560. And the AI achieved 2560. ✓
- Fuzz runs mostly lost (random paddle) — expected.

Now let me do a visual sanity check. I can't render canvas in Node without a library. But I can verify the layout numerically and also produce a quick SVG mock to eyeball the layout proportions. Let me generate a small SVG preview using the same constants to eyeball the layout — a nice sanity check (not shipped, or I could keep it out of the deliverable). I'll generate it in a temp file outside the deliverable... it must be in the current directory though. I'll generate it as a hidden file and delete it after.

Actually, better: I can verify visually by taking a screenshot with a headless browser if available. Let me check if chromium/puppeteer is available.

Let me check for chromium/google-chrome.

Chromium is available. I can take a screenshot of the page with `chromium --headless --screenshot`. But headless screenshots require the page to load; the game animates via rAF. A screenshot after some time should show the initial 'ready' state.

Let me run:
chromium --headless=new --disable-gpu --no-sandbox --screenshot=shot.png --window-size=1040,800 --virtual-time-budget=3000 file://.../index.html

Then read the PNG to look at it.

Also I can inject a query-driven state? Simpler: take a screenshot of the initial state, then a second one where I simulate play by... can't easily inject JS with --screenshot. But I can create a temporary test HTML that loads game.js and drives the game to a specific state, then screenshot it. Let's first do the basic screenshot.

Note: --virtual-time-budget advances virtual time so rAF runs. Good.

Let me do it.

Let me build a driver page that plays the game for a while and captures the canvas to a PNG data URL... but I can't read data URLs out of headless chrome easily. Alternative: use `--screenshot` with a driver HTML that runs the game with a scripted paddle for N virtual frames, so the screenshot shows mid-play with bricks broken, particles, trail, etc.

I'll create `.preview.html` that includes game.js but with an injected AI. Problem: game.js is an IIFE with no hooks. I can create a copy of game.js with the test hook appended (in a temp file) and a preview page that uses the hook. Let me do that: generate `.preview-game.js` = game.js with hook inserted, and `.preview.html` that loads it and drives the AI.

Then screenshot with --virtual-time-budget to advance frames.

Let me do it.

Wait — the hook is inserted before `restart(); requestAnimationFrame(frame);`? Let me check: `src.lastIndexOf("})();")` finds the final `})();`. The hook is inserted before that, so it comes after `restart(); requestAnimationFrame(frame);`. Good. But `globalThis.__T` is defined after the loop starts — fine since the AI runs on setInterval later.

Hmm, but `window.__T` vs `globalThis.__T` — in a browser, globalThis === window. Good.

Let me look at the screenshots.

I can't view images. I need another way to verify visuals. Options:
1. Use chromium headless with a script that dumps canvas pixel statistics (e.g., sample colors) — I can evaluate JS via `--headless --dump-dom`? Not enough. 
2. Use Chrome DevTools Protocol via a small Node script with `--remote-debugging-port` and the `chrome-remote-interface`? Not installed.
3. Simpler: write a Node script that reimplements... no.

Alternative approach: verify the canvas drawing by instrumenting the ctx stub in the Node harness to record draw calls and check that expected things are drawn (bricks count, HUD text, paddle, ball). That verifies the render code runs without errors and draws the right number of items. I already call T.render() in tests with a no-op ctx — no errors thrown.

Let me add a recording ctx to the harness that counts fill/stroke/arc/fillText calls and captures fillText strings, to confirm the HUD text and overlays appear, and that bricks are drawn (count of roundRect fills = 40 at start).

Also I can compute a crude "render map" by rasterizing the recorded draw calls myself... overkill.

Better idea: use chromium headless with `--virtual-time-budget` and a preview page that, instead of screenshotting, draws to the canvas and then outputs a text summary into the DOM, which I can read with `--dump-dom`. That gives real browser verification of the actual canvas rendering (e.g., getImageData statistics: count non-background pixels, colors present, etc.).

Let me do that: a preview page that runs the game for N frames, then uses ctx.getImageData to compute a histogram of colors and prints it into the document body; then `chromium --headless --dump-dom --virtual-time-budget=...`.

That's a solid verification: confirms bricks are drawn with the 5 row colors, the paddle, the ball, HUD text pixels, etc.

Let me write `.probe.html`:
- loads .preview-game.js (with hook)
- after a fixed number of frames (use a counter in the AI interval), stop and compute stats from the canvas: 
  - total pixels, count of pixels matching each row color (within tolerance), count of white-ish pixels (ball/paddle), count of text-ish pixels.
- write results into document.title / a <pre id="out">.

Then `chromium --headless --dump-dom --virtual-time-budget=8000 file://.../.probe.html` and grep the output.

Note: getImageData on a canvas with dpr scaling: canvas.width = 960 (dpr=1 in headless). Good.

Let me implement. I need the canvas element: document.getElementById('game').

Plan for probe:
```html
<script src=".preview-game.js"></script>
<script>
  const out = [];
  function log(s){ document.getElementById('out').textContent += s + "\n"; }
  // stop the AI after N frames and sample
  window.__probe = () => {...};
</script>
```
But the AI is in the hook with setInterval. Instead, let me generate a dedicated probe game file where I insert a probe driver instead of the AI driver.

Simpler: generate `.probe-game.js` with a driver that:
- counts frames in the rAF? I can't hook rAF easily... Actually I can wrap window.requestAnimationFrame before game.js runs? game.js captures the global requestAnimationFrame at call time (it calls requestAnimationFrame(frame) inside frame()). If I override window.requestAnimationFrame before loading game.js, the game will use my wrapper. In the probe HTML, I can put a script before the game script that wraps rAF to count frames and, after N frames, run the analysis. 

Let me do that:

```html
<script>
  window.__frames = 0;
  const raf = window.requestAnimationFrame.bind(window);
  window.requestAnimationFrame = (cb) => raf((t) => { window.__frames++; cb(t); });
</script>
<script src="game.js"></script>
<script>
  // drive: simulate keydown space to launch, and move the paddle with arrow keys / direct target? 
</script>
```
For the probe I mainly want a mid-play frame with some bricks broken, particles flying, and the ball in flight. I can:
1. dispatch a keydown ' ' to launch.
2. dispatch pointermove to move the paddle.
3. Let it run for N frames.
4. Analyze.

To break some bricks, just launch and let it bounce; after ~2s it will have hit a few bricks and produced particles.

Even better: dispatch keydown ' ' then run 120 frames (2s) → the ball will have hit bricks. Then sample.

Also test the 'won' state visuals: I can't easily reach 'won' without an AI. I could add a second probe page that cheats: after loading, use a hook... but game.js has no hooks. 

Alternative for probe: reuse `.preview-game.js` (which has the __T hook) and add the rAF wrapper + analysis in the probe page. The AI in the hook drives the paddle so bricks get destroyed. Then at frame N, analyze. And at frame M (large), the game should be 'won' → analyze the win overlay.

Let me build `.probe.html` using .preview-game.js with a frame-count-based analysis that logs at several checkpoints (e.g., frame 60, 600, 3000) into document body.

The hook's setInterval runs every 16ms of virtual time; with virtual-time-budget the intervals fire. Good.

Let me write the probe with analysis function:

```js
function analyze(label){
  const c = document.getElementById('game');
  const ctx = c.getContext('2d');
  const d = ctx.getImageData(0,0,c.width,c.height).data;
  const counts = {};
  let nonBg = 0;
  for(let i=0;i<d.length;i+=4){
    const r=d[i],g=d[i+1],b=d[i+2];
    const key = (r>>4)+','+(g>>4)+','+(b>>4);
    counts[key]=(counts[key]||0)+1;
  }
  ...
}
```
I'll check specific expected colors:
- brick colors: #ff5f6d, #ff9f43, #ffd93d, #5ce0a5, #5aa9ff → count pixels within tolerance 30 for each.
- paddle light #eaf1ff / #a9c0ea
- ball white #ffffff
- HUD text #f2f6ff

And report counts. Also report state via __T.

Let me write it.

Also verify the canvas is exactly 960x600 CSS px in the layout (check getBoundingClientRect).

Let me write the probe page.

The preview-game.js hook has `score:()=>score` etc. Good.

But the hook's AI uses `window.__T.state` (getter) — fine.

Also the probe's `T.score()` etc.

Note: the probe page doesn't include the canvas element — it references `document.getElementById('game')` but there's no canvas in .probe.html! game.js does `document.getElementById('game')` and would get null → crash. I need to include the canvas. Let me add `<canvas id="game" width="960" height="600"></canvas>`.

Let me fix.

The probe page has no CSS, so the canvas will be at its attribute size 960x600 (dpr 1 in headless). Good.

Run with dump-dom and virtual-time-budget large enough to reach 30000 frames? Virtual time budget of e.g. 60000ms → 60s of virtual time → ~3600 frames at 60fps. To reach 30000 frames I'd need 500s of virtual time. The AI won at ~5000 frames in Node at 1/60 dt. In the browser, dt is real elapsed virtual time. Let me set --virtual-time-budget=120000 (120s → ~7200 frames) and checkpoints up to 8000.

Let me adjust checkpoints to [30, 120, 400, 1200, 3000, 6000] and budget 120000.

Also setTimeout(tick, 30) — with virtual time these fire quickly.

Let me update checkpoints and run.

The hook is missing: `window.__T` is undefined → "missing hook". Why? Because `.preview-game.js` was generated from the *older* game.js? No — I regenerated it after the geometry edit? Let me check: I generated .preview-game.js in the command that created the preview; that was after the geometry edit. The hook there defines `globalThis.__T = {...}`.

But wait — the probe overrides `window.requestAnimationFrame` BEFORE loading .preview-game.js. That's fine.

Why is __T undefined? Possibly because game.js threw an error before reaching the hook. Or because `.preview-game.js` hook insertion used `src.lastIndexOf("})();")` — the last occurrence. In game.js the final line is `})();`. Yes.

Hmm, but maybe an error occurred. Let me check by dumping console output: chromium headless with --enable-logging=stderr --v=1 to capture JS errors. Let me just check .preview-game.js tail.

Also note the dump-dom shows the pre content only has the first two log lines, meaning the setTimeout(200) analysis never ran (or threw at `T.bricks` since T is undefined). Right — analyze() throws because T is undefined. And the INITIAL analyze... wait, INITIAL analyze isn't in the output, so it threw. Consistent with T undefined.

Let me check the tail of .preview-game.js.

The hook is there. So why is window.__T undefined in the probe page? Because the script src is `.preview-game.js` — a dotfile. Maybe Chromium refuses to load a file whose name starts with a dot? Unlikely... but the file:// URL should work.

Or: the script threw an error before reaching the hook. Let me capture console errors with --enable-logging=stderr.

Let me test with a simpler check: add a script after the game script that logs typeof window.__T... it already does (T ? 'ok' : 'missing hook').

Let me run chromium with --enable-logging=stderr --v=2 and grep for errors.

Line 250 in .preview-game.js: `document.getElementById('restart').addEventListener(...)` → null, because .probe.html has no restart/sound buttons. So game.js threw at that line, before defining __T and before starting the loop.

Important insight: **game.js requires the `restart` and `sound` buttons to exist**. In index.html they do, so the real page is fine. But this reveals a fragility. Let me make game.js defensive: guard the button lookups. That's good practice and lets the probe work.

Let me refactor:
```js
  const btnRestart = document.getElementById('restart');
  if (btnRestart) btnRestart.addEventListener('click', ...);
  const btnSound = document.getElementById('sound');
  ...
  function setMuted(v){ muted = v; if (btnSound) btnSound.textContent = ...; }
```

Also `canvas` could be null → guard? Not needed for the deliverable, but a null-canvas guard is cheap. I'll just guard the buttons.

Then regenerate .preview-game.js and re-run the probe.

Also update the Node test: it stubs getElementById for any id, so it worked.

Let me apply the guard.

The Node test checks `els.sound.textContent !== 'Sound: off'` — els.sound is created by getElementById stub, and btnSound is captured at load time. Since the stub caches elements, els.sound is the same object. Good.

Now regenerate .preview-game.js and re-run the probe.

At frame=0 nothing is drawn yet (litPixels=0) — the rAF hasn't run. And only the INITIAL checkpoint logged; the tick loop didn't produce more. Because `--virtual-time-budget` with setTimeout... The tick uses setTimeout(tick,30) and analyze at checkpoints based on __frames. Only INITIAL appeared, meaning __frames never advanced past 30? Or the tick loop threw.

Hmm, "INITIAL frame=0 state=playing" — state is 'playing' because the AI interval called launch. So timers run. But rAF frames: __frames=0 at INITIAL (200ms virtual). Then tick() at 30ms intervals... The dump-dom happens when the virtual time budget is exhausted (140s). So there should be thousands of frames.

Unless rAF is throttled in headless without a compositor... In headless=new, rAF should run. But `--dump-dom` may snapshot before rendering completes? Actually the output shows only INITIAL, so tick() either threw or __frames stayed 0.

Possibility: my rAF wrapper breaks the loop. `window.requestAnimationFrame = (cb) => raf((t) => { window.__frames++; cb(t); });` — game.js calls `requestAnimationFrame(frame)` — this resolves to window.requestAnimationFrame at call time. Fine.

But wait: game.js's first call is `requestAnimationFrame(frame)` at the end of the IIFE, which happens AFTER my wrapper is installed (the wrapper script is before the game script). Good.

Hmm, but maybe rAF in headless with virtual time doesn't fire at all, so __frames stays 0 and tick() keeps rescheduling without hitting checkpoint 30... but then `if (window.__frames < 40000) setTimeout(tick,30)` loops forever until the budget ends, and dump-dom shows the state at that time — which would still show only INITIAL. That matches: rAF never fired.

Actually, litPixels=0 at frame 0 confirms nothing was drawn yet. If rAF had fired even once, litPixels would be > 0 at the next checkpoint.

So rAF isn't running in this headless mode. Known issue: headless Chrome may not run rAF without a display... but headless=new usually does render. Let me test with a minimal page that counts rAF ticks.

Alternative: drive the game manually in the probe by calling the internal frame? I don't have access to `frame`. But I can add to the hook a manual step function: expose `update` and `render` and drive them from setInterval (which does work). Let me expose `step: (dt) => { update(dt); render(); }` in the hook and drive it from the interval at 16ms.

That's a reliable way to get real browser rendering for the probe. Let me do that.

Also, the screenshot earlier (.shot-play.png) was produced — but I can't view it. The pixel probe is the way.

Let me regenerate the preview game with a `step` hook and drive with setInterval.

Now update .probe.html to drive `__step` from a setInterval and analyze at frame checkpoints. Let me rewrite the probe script section.

Note: `window.__step()` calls `window.__T.step(1/60)` which calls update+render. But `render()` uses `ctx.clearRect` and setTransform — fine.

Also `analyze` uses `c.getContext('2d')` — returns the same context. getImageData works.

Run with virtual-time-budget=140000 so the 1ms interval can run ~12000 times (12000ms). Actually setInterval(1ms) with virtual time 140000ms → up to 140000 firings, but we stop at 12000 frames. Good.

Let's run.

Excellent — real browser rendering confirmed:
- Canvas is 960×600 CSS and backing (dpr 1 in headless).
- All 5 row colors present with ~4400-4850 px each (a 96×26 brick ≈ 2496 px; 8 bricks per row ≈ 19968 gross, but the gradient means only the mid-band matches the exact fill color within tolerance 26 → ~4500 plausible).
- Paddle color present (~4400 px; paddle 112×16 = 1792 px, plus glow/gradient — plausible).
- Ball white ~800 px (ball radius 7 → area 154; plus glow gradient and trail and HUD "00000" text white... hudText is separate at 1016). Hmm ballWhite=787 includes the ball's white core + glow + trail + paddle highlight (#eaf1ff is within 26 of 255,255,255? |255-234|=21 <26 → yes, the paddle's top gradient counts). Fine.
- HUD text pixels ~1000 → text is being drawn.
- Bricks decrease as destroyed; at the end all rows = 0 and state='won' with score 2560.
- lit pixels decrease as bricks vanish.

Everything renders. Now let me also verify the win overlay text and the 'lost' overlay render. The FINAL check shows state='won' and lit=12495 (overlay text + paddle + ball). Good enough.

Let me also verify the pause overlay renders and the 'lost' state. I'll add a second probe variant that forces pause and loss. Actually simpler: a probe that (a) pauses at frame 100 and analyzes, and (b) uses a bad AI so it loses.

Let me do a quick second probe: `.probe2.html` with a "lazy" step driver (no paddle movement) → should reach 'lost' and render GAME OVER. And a pause test: call T.pause? I didn't expose pause. I can dispatch a keydown event on window with key 'p' — game.js listens on window keydown. Let me dispatch `window.dispatchEvent(new KeyboardEvent('keydown',{key:'p'}))`.

Let me write probe2 to test: pause overlay pixels, resume, and the lost state.

Also test the 'ready' overlay text ("PRESS SPACE OR CLICK TO LAUNCH").

Let me write it.

The hook exposes `ball` getter returning the ball object → `T.ball.stuck` works.

Note: phase 2 waits for state 'ready' (life lost). The lazy paddle: T.step doesn't move the paddle toward the ball, but the paddle stays at center; the ball will eventually miss → life lost. Good.

Also `key('p')` dispatches keydown; game.js's handler checks `e.target.tagName` — for a dispatched KeyboardEvent on window, target is window, tagName undefined → `if (t && (t.tagName === ...))` → t is window object, truthy, tagName undefined → fine.

Also `ensureAudio()` is called on keydown — AudioContext exists in headless Chrome; creating it is fine.

Run.

Interesting problem! At f=60, state is 'ready' with stuck=true and destroyed=0 — the ball never launched! Because in this probe I never launch: the hook's `__step` (which auto-launches) isn't used here; I call `T.step()` directly, which only updates+renders. The ball stays stuck in 'ready' forever. So no life was lost and the game never progressed → TIMEOUT.

Also note: 'ready' state means the ball never falls → no life lost. That's correct behavior (the ball can't be lost while stuck).

I need to launch. Let me call `T.launch()` at the start.

Also the PAUSE-OVERLAY region shows lit=6480, darkOverlay=31235 → the dim overlay and text are rendering. Good. But bright=0 — the "PAUSED" text is #e8f0ff (232,240,255) which should count as bright (r>200,g>200,b>210) → 232>200 ✓, 240>200 ✓, 255>210 ✓. Hmm bright=0 means the PAUSED text isn't there? But lit=6480 counts r+g+b>200 which includes the dimmed bricks/paddle showing through the 0.62 alpha overlay.

Wait — the overlay is drawn with alpha 0.62 over everything, so the text drawn AFTER the dim should be bright. Unless... the region 300..660 x 250..360 contains the "PAUSED" text at y=285 centered at x=480. It should be bright.

Hmm, but `bright` requires b > 210 AND r>200 AND g>200. #e8f0ff = (232,240,255). Should match. Unless the text wasn't drawn because... Let me check: after `key('p')` at f=60, I immediately call `region(...)` — but the render for the paused state hasn't happened yet! The pause happened via the key event, but `render()` was last called during `T.step()` before the key. So the canvas still shows the pre-pause frame. That explains bright=0.

I need to call T.step() (or at least render) after the key press before sampling. Let me restructure: after key('p'), call T.step(0) — but step calls update(dt) with dt=0 then render. update with dt=0 while paused returns early. Good, so T.step(0) just renders. Let me use T.step(0).

Similarly for the READY-HINT and GAMEOVER regions.

Let me fix probe2: add T.launch() at the start, and call T.step(0) after state changes before sampling.

Also phase 2 → wait for state 'ready' after having lost a life. But after resume, state is 'ready' again (ball was stuck when paused). So phase 2 immediately triggers LIFE-LOST-READY incorrectly (it's just the initial ready state, not a life loss). Let me track lives: wait until T.lives() < 3.

Let me rewrite probe2 more carefully with an explicit sequence:
1. launch, run 60 frames with a tracking AI (so it doesn't die yet) → PLAYING snapshot.
2. key('p'), T.step(0) → PAUSED snapshot + region.
3. run 60 more steps → verify the ball didn't move while paused.
4. key('p') → resume → snapshot.
5. run with lazy paddle until lives<3 → LIFE LOST snapshot (state 'ready', lives 2) + READY-HINT region.
6. continue lazy until state 'lost' → GAME OVER snapshot + region.
7. key('r'), T.step(0) → verify full reset.

Let me implement with a state machine driven by a counter.

I'll add a tracking AI function for phase 1.

Let me rewrite.

Note: in phase 2 and 3, the paddle is lazy (not tracked) so the ball will be missed. But in phase 2 the ball may already be near the paddle... fine.

One concern: in phase 1, `key('p')` then `T.step(0)` — update(0) while paused returns early after time += 0, then render draws the pause overlay. Good.

Run.

Everything works in a real browser:
- PLAYING: bricks/paddle/ball rendered.
- P (pause): state=paused, dark overlay 31137 px, bright text 1916 px ("PAUSED" text) ✓
- Nothing moves while paused ✓
- Resume returns to 'playing' ✓
- Life lost: lives 3→2, state 'ready', ball stuck ✓ (READY-HINT lit=1918 — the hint text is drawn in a translucent color so brightText=0, expected since the color is rgba(200,225,255,~0.6) → r≈130 after blending... fine, lit=1918 shows text pixels present)
- GAME OVER: state 'lost', lives 0, dark overlay + bright text 1125 ✓
- R restart: score 0, lives 3, destroyed 0, alive 40, stuck, state 'ready' ✓

Now a few remaining polish items to verify in the real page:
1. Mouse control — verify pointermove moves the paddle. Let me probe: dispatch a PointerEvent with clientX and check paddle.x after a step.
2. Arrow keys move the paddle (already tested in Node).
3. Click to launch / restart (pointerdown) — test via dispatching pointerdown.
4. Blur/focus pause — tested in Node.
5. Sound: verify WebAudio nodes are created (no errors). I can check that AudioContext exists and no console errors occur when hitting a brick. The earlier probe ran with audio (ensureAudio called on keydown). No errors reported. Let me explicitly check for console errors in the probe run with audio enabled.

Let me write probe3 for pointer input + audio sanity.

Actually, let me combine: probe3 dispatches pointermove and checks paddle follows; dispatches pointerdown and checks launch; then runs a while and reports any window.onerror captures.

Let me add `window.onerror = (m) => log('JS ERROR: ' + m);` to the probes.

Let me write probe3.

T.speedNow isn't exposed. Let me add `speed` getter to the hook... the hook has no speed. Let me just regenerate the preview game with a `speedNow` accessor. Simpler: modify the probe to not print speed. Let me regenerate .preview-game.js with speed exposed, since it's useful.

Let me regenerate with `get speed(){return speed;}` and use T.speed in probe3.

All input paths verified in a real browser:
- Click launches ✓
- Mouse moves the paddle (with a fast lerp; 3 frames to reach 120 from 480 → 200.3, converging) ✓
- Clamped to [70, 890] ✓
- Arrow keys move the paddle (132.7px in 10 frames ≈ 796 px/s, close to 940 due to lerp lag) ✓
- Long run wins with speed 680 (cap 760 never reached, as designed) ✓
- No JS errors with audio active ✓

One consideration: the mouse lerp (rate 30/s) means the paddle reaches the cursor in ~3-5 frames (50-80ms). That's slightly laggy for a breakout. Let me increase the lerp rate to make mouse following snappier while keeping arrow keys smooth. With k = 1 - exp(-dt*30), at 60Hz k=0.393 per frame → 63% of the gap closed in 2 frames. Reaching 120 from 480 took 3 frames to get within 80px. Hmm, that's a 360px gap; after 3 frames it's at 200 (80px remaining). Time constant 1/30 s = 33ms. It's fine but let me bump to 45 for snappier feel: time constant 22ms.

Actually, for mouse control, direct assignment is the most responsive. A hybrid: if the target came from the mouse, snap more aggressively. Let me just raise the rate to 45 — still smooth, avoids jitter, and effectively instant.

Hmm, but there's a subtlety: with a high lerp rate, `paddle.vx` (used for spin) becomes large spikes. paddle.vx * 0.18 added to vx, then normalizeSpeed caps the magnitude to `speed`. A huge vx spike would dominate the direction → the ball could be launched nearly horizontally, but clampDirection fixes |vy| >= 0.3*speed. So it's bounded. But it could feel erratic. Let me clamp paddle.vx contribution: use `clamp(paddle.vx, -600, 600) * 0.15`.

Let me apply both tweaks: lerp rate 45, and clamp the paddle spin contribution.

Also, one more thing to double check: the arrow-key speed 940 px/s with lerp 45 → the paddle lags slightly behind the target; observed 796 px/s effective. With rate 45 it'll be closer to 940. Fine.

Let me also reconsider `MAX_BOUNCE = 62°` — at the paddle edge the ball leaves at 62° from vertical, i.e., 28° from horizontal. clampDirection requires |vy| >= 0.3*speed → angle <= 72.5° from vertical. So 62° is allowed. Good.

Now let me finalize:
1. Bump lerp to 45, clamp spin contribution.
2. Re-run the Node test suite to confirm nothing broke.
3. Clean up the temp files (.test.cjs, .preview-game.js, .probe*.html, .shot*.png). The task says everything lives in the current directory and index.html is the entry point; extra hidden test files are probably fine but cleaner to remove. I'll remove them to keep the deliverable clean. Actually, keeping a test file could be seen as clutter. I'll delete all the dot-files.

Let me also re-read the final game.js fully one more time for a careful review, and check index.html.

One more feature check from the spec: "A paddle on the bottom edge" ✓. "It cannot leave the field" ✓. "A ball that starts stuck to the paddle and launches on Space or a click" ✓. "3 lives" ✓. "Score: 10 points per brick hit, 50 for destroying one" ✓. "Win when every brick is gone, lose at zero lives. Both states show a clear message and offer a restart that fully resets" ✓. "requestAnimationFrame + frame-rate independent" ✓. "No tunneling/sticking/escaping" ✓. "Speed increases gradually with a cap" ✓. "Pause on P or when the window loses focus" ✓. "Juice: hit flash, particles, screen shake, trail, WebAudio sound" ✓. "All graphics via canvas API" ✓. "Controls shown outside the canvas" ✓.

One gap: the spec says the paddle is controlled by mouse AND arrow keys — done.

Another: "Bricks in the top two rows take two hits (visibly damaged after the first)" ✓ (cracks + darkening).

Let me apply the paddle tweaks and re-test.

Also: should I double check that `pointerdown` on the canvas doesn't prevent the arrow keys from working? No.

Another detail: `canvas.addEventListener('pointerdown', ... e.preventDefault())` — prevents text selection. Good.

Let me make the edits.

Wait — `clamp(paddle.vx, -600, 600) * 0.15` is added to vx, then normalizeSpeed() renormalizes to `speed`. But if the paddle is moving fast, the added term could dominate and make the ball nearly horizontal — clampDirection fixes that. OK.

Hmm, actually there's a subtle issue: `Math.sin(ang)*speed + spin` then `ball.vy = -Math.cos(ang)*speed`, then normalizeSpeed scales both to speed. If spin is large (90), the direction shifts a bit. Fine.

Now re-run the Node test suite.

All tests pass. Now let me re-run the browser probes once with the updated game to make sure nothing regressed, then do a final read-through of both files, then clean up temp files.

Let me regenerate .preview-game.js from the updated game.js and re-run probe1 and probe3 quickly.

probe1 shows "BUDGET-END f=0" — the interval-driven `__step` no longer exists in the new hook (I removed `__step` when regenerating). probe1 calls `window.__step()` which is now undefined → the interval threw. But the canvas still shows a fully rendered initial frame (rendered by the real rAF? No — rAF doesn't tick in headless... yet lit=110567 and all rows present).

Hmm, interesting: the canvas IS rendered. That means `render()` ran at least once. How? Because... hmm, `restart()` doesn't render. The first render happens in `frame()`. So rAF DID run at least once. Earlier probes showed rAF frames counting. In probe1, `window.__frames` was incremented only by my rAF wrapper — which I removed in the current .probe.html version. Right! The current .probe.html sets `window.__frames = 0` and never wraps rAF; it calls `window.__step()` which no longer exists → throws on the first interval tick. But the game's own rAF loop ran (rendering the field), so the canvas is fully drawn.

So rAF does work in headless after all — earlier the issue was my wrapper. Good: the game's own rAF loop renders in a real browser.

Anyway probe3 confirms the full win path with the game's own step driver.

Let me re-run probe1 with a fixed version that uses T.step to get the progression checkpoints, to double check the mid-play rendering after the tweaks. Actually probe3 already ran a full game to 'won' with no JS errors. And probe1's canvas shows all 5 rows + paddle + ball + HUD rendered.

Let me do one more quick probe1 variant using the game's own rAF loop and sampling at virtual-time checkpoints (based on a timer, not frames). Simpler: sample at virtual times 1s, 3s, 10s, 30s, 60s using setTimeout, and read T.state.

Let me just patch .probe.html to use setTimeout-based checkpoints and T.state.

Interesting: state='playing' but destroyed=0 forever and the canvas is static. The game rendered once (at 2000ms) and then... nothing changes. So rAF ran only a couple of times then stalled? destroyed stays 0 and score 0 — the ball isn't moving.

Hmm, `state=playing` means launch() was called by my interval. But the ball never hits anything. And the canvas is identical between 6000ms and 60000ms → the game isn't advancing.

This suggests rAF is NOT running in this headless configuration (the single render we see came from... hmm, if rAF never ran, render() would never be called and lit would be 0).

At AT 500ms: lit=0 → nothing rendered. At 2000ms: fully rendered. So exactly one frame ran between 500ms and 2000ms, then it stalled. That's consistent with headless rAF being throttled to a single frame when there's no compositor... but probe3 worked (it drove everything with its own setInterval calling T.step).

So in headless, rAF fires only once (or very few times). That's a headless quirk, not a game bug — probe3's manual stepping proved the game logic and rendering work.

But I want to be sure the real page animates in a real browser. Let me verify rAF actually loops by measuring frames over virtual time in a plain page. If headless throttles rAF, I can instead verify with `--run-all-compositor-stages-before-draw` or by using `google-chrome-stable --headless=old`? Let me test a minimal rAF counter page.

Actually, a simpler and more reliable check: use the screenshot approach with `--virtual-time-budget` — the earlier .shot-play.png was 69KB vs .shot-ready.png 75KB, suggesting different content, but I can't view them.

Let me test rAF ticking in headless with a counter page.

The dump-dom shows the pre content empty — the DOM dump happens before rAF runs (headless new dumps immediately after load). So this test is inconclusive; dump-dom snapshots too early.

Let me instead use a screenshot with a virtual time budget and check whether the canvas content changes between two different budgets — I already did that with .shot-play.png vs .shot-ready.png (different sizes). But I can't view images.

Better: compare pixel data between two screenshots programmatically. I can use Node to decode PNGs? No image lib. But I can compare file bytes/sizes — not conclusive.

Alternative: use `--virtual-time-budget` with a page that, at the end (via setTimeout at the budget), writes the canvas stats into the DOM. That's exactly what probe1 did — and it showed a rendered frame at 2000ms but no progression. The key question: did rAF run many times or just once?

In probe1, `window.__frames` stayed 0 because I removed the rAF wrapper. Let me re-add the rAF counter wrapper to probe1 and see if __frames advances with virtual time. Earlier with the wrapper, __frames stayed 0 too (the first probe run showed frame=0 at INITIAL and no checkpoints hit).

Hmm, but in that first probe the game crashed (missing buttons) so rAF never started. Then in the second probe version I used __step. So I never actually measured whether the game's rAF loop advances under virtual time.

Let me do a clean test: a page with the rAF wrapper + game.js (real one, with buttons present) and log __frames at virtual times.

Actually simpler: use `--virtual-time-budget` on a page that logs `__frames` at 1000ms and 5000ms via setTimeout.

Let me build a minimal test page using index.html's own structure? I'll create .probe4.html that includes the real index.html content? Easier: use the .preview.html (which is index.html with .preview-game.js) plus an injected counter script.

Let me create .probe4.html = index.html + rAF wrapper script (before game.js) + a script that logs frames at virtual times.

In headless Chrome with virtual time, rAF only fires ~2 frames (it's throttled without a real display/compositor). This is a headless artifact, not a game bug — the game's rAF loop is standard and correct.

To be extra safe and to prove the loop is correct, I can verify with a real-time (non-virtual) run using CDP... but no puppeteer. Alternatively use `--headless=old`? Let me try `--headless` (old) with `--virtual-time-budget` or with real time and a screenshot after a delay.

Actually, let me try `--headless=old` which uses the old headless mode with a proper compositor-ish behavior. Or use `--headless=new --disable-gpu=false`? Let me quickly test the raf.html counter with `--headless=old`.

Actually, a simpler decisive test: run chromium in real time (no virtual budget) with `--screenshot` after a delay... screenshots are taken after load, no delay control.

Let me try `--headless=old` on raf.html with dump-dom and a virtual budget.

Honestly, the rAF loop is textbook: `requestAnimationFrame(frame)` called at the end of `frame()`, started once. There's no doubt it animates in a real browser. The headless throttling is well-known (headless=new only produces frames when a screenshot/compositor commit happens).

Still, let me do one quick sanity test with --headless=old to see if frames advance; if yes, great.

Confirmed: headless Chrome (both modes) doesn't drive rAF in these dump-dom runs — a well-known headless artifact. The game's loop is standard and correct; probe3 proved the update+render pipeline works when driven.

To get one more piece of evidence that the shipped page animates, let me take two screenshots at different virtual-time budgets of the real index.html and compare their bytes with a simple hash — if the game advanced, the images differ. Earlier .shot-ready.png (75253) vs .shot-play.png (69297) vs .shot-late.png (69373) — those used .preview.html with the AI. Different sizes → different content → the game state changed over virtual time in screenshot mode (screenshots force a compositor commit, which drives rAF).

Let me do a definitive check: take screenshots of the real index.html at two budgets and compare hashes; also compare against a screenshot taken with a keydown... can't inject.

Actually a better definitive test: use the screenshot mode with the probe page that writes stats into the DOM — dump-dom won't show them, but the screenshot will show the canvas. I can compare the canvas pixels between two virtual-time budgets by hashing the PNGs. If the game advanced, the hashes differ.

Let me do: .probe5.html = index.html + a script that auto-launches after 300ms (dispatch keydown ' ') and drives the paddle with a timer. Screenshot at budget 2000 and budget 8000, compare md5. If they differ → the game advanced in real rAF-driven rendering.

Let me do that.

The live canvas pixel hash changes across virtual-time budgets (3802101317 → 4011086064 → 2985022834), and the screenshots differ. So the shipped index.html genuinely animates via its own rAF loop in a real browser, and the ball/paddle move (the hash changes because the game state advances).

Now let me do a final careful read-through of game.js and index.html, then clean up the temp files.

Let me read the full game.js once more in chunks to double-check for any leftover issues.

One issue I notice: `window.addEventListener('blur', () => pause('blur'))` — in browsers, clicking a button inside the page doesn't blur the window. But the `blur` event on `window` fires when the window loses focus. Fine.

Another: `window.addEventListener('focus', ...)` auto-resumes. But if the user paused with P and then the window gets focus events... pausedBy==='key' so no auto-resume. Good.

Potential annoyance: pressing the Restart button gives it focus; then pressing Space would activate the button again — but I blur the button on click and also blur BUTTON targets in keydown. Good.

Another consideration: `e.preventDefault()` on arrow keys and space globally prevents page scrolling — good, but it also prevents Space from activating a focused button (we blur anyway).

Now let me check the remaining part of the file (render + loop) once more, particularly the HUD text and the 'ready' overlay, and confirm the file ends properly.

Let me read 310-470 and 470-620 quickly... I already reviewed part 2 when writing it. Let me spot-check the region around the physics tail and the render start to ensure the splice is clean.

One thing to double-check: in `hitBrick`, when the last brick is destroyed, `state = 'won'` — but `brickCollisions` then calls normalizeSpeed etc. and returns true. `stepMove` returns. `updateBall`'s while loop checks `state === 'playing'` → exits. Good.

Another: when state becomes 'won', the ball keeps its velocity but is no longer updated. drawBall still draws it. Fine.

A subtle issue in `paddleCollision`: `if (hit.ny < -0.4)` then `if (ball.vy <= 0) return false;` — if the ball is overlapping the paddle while moving up (e.g., just after a bounce), we return false and skip brick collisions for that substep (since stepMove does `if (ball.vy > 0 && paddleCollision()) return;` — actually stepMove only calls paddleCollision when ball.vy > 0, so the `ball.vy <= 0` guard inside is redundant). Fine.

Another: after a paddle top-face bounce we set ball.y = PADDLE_Y - BALL_R - 0.01. Good.

Now, one gameplay concern: the ball can hit the paddle's *side* when the paddle is moved into the ball. That reflects horizontally — reasonable.

Another: the ball could get trapped between the paddle and a wall (paddle at min x=70, paddle spans 14..126; wall at 14). If the ball is at x=21 (WALL_L+R=21) and the paddle's left edge is at 14, the ball is above the paddle → top-face bounce. Fine.

Let me now check the last part of the file (render/loop) — I wrote it and verified via the browser probes. Let me read the tail to confirm the splice is clean and there's no leftover placeholder.

Clean: no placeholders, no external references.

One last check on index.html: the canvas has `width="960" height="600"` attributes and CSS `width:960px; height:600px; max-width:100%; height:auto;`. Wait — I have both `height: 600px` and `height: auto` in the CSS. Let me check the order:

```css
  canvas {
    display: block;
    width: 960px; height: 600px;
    max-width: 100%; height: auto;
    ...
  }
```
The later `height: auto` overrides `height: 600px`. So the CSS height is auto → determined by the aspect ratio from the width (since max-width:100% may shrink the width, height auto keeps the intrinsic aspect ratio 960:600). Good — that's what I want for responsiveness. But `width: 960px` with `max-width: 100%` → on narrow screens the width shrinks and height auto scales proportionally. Good.

However, game.js's setupCanvas sets `canvas.style.width = W + 'px'; canvas.style.height = H + 'px';` inline — inline styles override the stylesheet! That would force 960x600 CSS px even on narrow screens, breaking responsiveness (the canvas would overflow). The pointer mapping uses getBoundingClientRect so it'd still work, but the layout would overflow on small screens.

Fix: in setupCanvas, only set style width/height if they differ... Actually better: don't set inline styles at all; instead rely on CSS. But then the backing store size (canvas.width/height attributes) must match the CSS size × dpr. Since CSS controls the display size (960px max), setting the backing store to 960*dpr is right, and CSS `width:960px; max-width:100%; height:auto` handles display.

But if the CSS display width shrinks (e.g., 700px on a narrow viewport), the backing store stays 960*dpr and the browser scales it down — still crisp. Good.

So: remove the inline style assignments from setupCanvas. But then `canvas.style.width` is unset and the CSS rule governs. The CSS rule sets width:960px explicitly, so display size = min(960, container). Good.

Let me remove the inline style lines. Also, since the CSS already sets width/height, the `height:auto` in CSS keeps the aspect ratio.

Hmm, careful: with `height: auto` and the canvas element having a `height` attribute of 600, `height:auto` for a replaced element uses the intrinsic aspect ratio → 600 when width is 960. ✓ (verified by the probe: CANVAS css=960x600).

Let me remove the inline style setting.

Also, one more consideration: `setupCanvas()` is called every frame and compares `canvas.width === Math.round(W*d)`. Fine.

Let me make that edit and re-verify with a probe (canvas css size 960x600 at desktop width, and check a narrow viewport).

Let me also test a narrow viewport screenshot/probe: window-size=700 → the canvas should shrink to fit (max-width 100% of .wrap which is max-width 100%). Let me probe the rect at window-size 700.

Wait — there's a subtlety. The CSS sets `width: 960px; max-width: 100%; height: auto;`. With `height: auto` and the canvas's `height` attribute = 600, the intrinsic ratio is 960:600 = 1.6. But after setupCanvas sets canvas.width = 960*dpr (e.g., 1920 at dpr 2), the intrinsic ratio becomes 1920:1200 = 1.6 — same. Good.

But at dpr 2, canvas.width = 1920, canvas.height = 1200 → intrinsic ratio unchanged. Good.

Now verify with a probe at desktop and narrow widths.

Let me create a small probe that logs the canvas rect and the pointer mapping accuracy.

The canvas is exactly 960×600 CSS px at ≥1040px viewport width, and scales proportionally (aspect 1.600 preserved) on narrower viewports with no horizontal overflow. The pointer mapping uses getBoundingClientRect ratio so it stays correct when scaled.

Let me verify the pointer mapping at a scaled size quickly — probe3 verified at 960. The formula `(clientX - rect.left) * (W / rect.width)` is correct for any scale.

Now re-run the Node test suite one final time (after the setupCanvas change), then clean up temp files.

Also let me double check the dpr=2 case: `--force-device-scale-factor=2`.

At dpr=2 the backing store is 1920×1200 with CSS 960×600 → crisp rendering. All tests pass.

Final: clean up the temp/hidden files, then read back index.html fully one last time.

Files to remove: .test.cjs, .preview-game.js, .probe*.html, .shot*.png, .h*.png, .probe4/5/6. Keep .session (not mine).

Let me list first.

I need to remove .dbg.cjs too. Then read back index.html and game.js one final time.

The user hasn't asked anything substantive yet — the last message was just system instructions being acknowledged. There's no actual task. My previous turn had no meaningful reasoning content; I simply acknowledged the instructions.

index.html is complete and correct.

One last detail: the `.sub` says "40 bricks · 3 lives · 8 × 5 grid" ✓.

Let me do a final read of the render section of game.js (lines ~470-700) to make sure everything is consistent after the splice — particularly that `drawHUD` uses the right coordinates and there are no duplicated/missing functions.

Let me grep the function list.

All functions present, no duplicates. The file is coherent.

One final consideration: `drawHUD` bottom hint at y=590 and the FLOOR line at 566 — the hint sits in the bottom strip. Good.

I'm done. Let me write a brief summary.

Actually, one more consideration about the requirement "A paddle on the bottom edge". PADDLE_Y = 540, field floor 566 — the paddle is 26px above the field's bottom line, which is visually "on the bottom edge" of the play area. Fine.

Also "Score and lives are visible during play" — HUD top strip. ✓

Let me also double check the `banner` decay: `if (banner > 0) banner -= dt;` and drawBanner uses clamp(banner/1.1). For the win banner set to 1.4, alpha clamps to 1. Fine.

Final answer summary.