Snake · qwen3.8-flash

Let me start by looking at the working directory.

Let me write the index.html file with a complete Snake game.

Design:
- Canvas 20x20 board, cell size 24px => 480x480 canvas. Use devicePixelRatio scaling maybe. Keep simple.
- Game loop with setInterval-ish using requestAnimationFrame and accumulated time for step timing (speed maybe 110ms per step).
- Direction queue: pending turns buffered, ignoring reversal into neck. Process queue one turn per step.
- Food placement in unoccupied cell.
- Wall collision, body collision (allow moving into tail cell that vacates on non-growing step).
- Start, Pause/Resume, Restart buttons. Keyboard: Space for pause/resume, Enter to start, R restart maybe. Arrow keys preventDefault.
- Score display, controls display, status display (Ready / Running / Paused / Game Over / You Win).
- Win state: when snake fills board, show win and don't place food.

Implementation details:

snake = array of {x,y}, head at index 0. dir = {x,y}.

Queue logic: keep `queue` of directions. On keydown arrow: compute candidate dir; compare against last effective direction in queue (or current dir if queue empty) — if candidate is opposite or same as that, ignore (same -> ignore to avoid duplicates? Requirement only says ignore reversal; ignoring same-dir duplicates is fine and harmless). Then push to queue with max length ~3.

On step: if queue.length, dir = queue.shift(). Then compute new head = head + dir. Check wall. Check body collision: cells occupied by snake except the tail (last element) if not growing. Growing means new head position === food position.

Logic:
```
const willGrow = (newHead.x === food.x && newHead.y === food.y);
const bodyToCheck = willGrow ? snake : snake.slice(0, snake.length-1);
// check if any cell in bodyToCheck equals newHead -> dead
```
Actually careful: if not growing, the tail cell vacates so moving into it is allowed. If growing, tail doesn't vacate so moving into tail is death. Also moving into head-to-neck cell (length>=2, index1) is death by body collision (though reversal is prevented). Note: snake length 1 - special case, moving into itself at index 0? newHead can't equal head since dir nonzero. Fine.

Then: snake.unshift(newHead); if willGrow { score++; place food or win } else { snake.pop(); }

Win: if snake.length === 400 -> win state. Also after eating, if no free cells -> win.

Pause: state 'paused'. Start button: if state 'ready' or 'over'/'won' -> start fresh? Let's define buttons: Start (starts from ready, or resumes from over? no). I'll make three buttons: Start, Pause/Resume, Restart. Start begins from ready state (initial length 3). If game over, Start acts like starting a new game too (or disabled). Simpler: Start → if state==='ready' start running; if 'over'/'won' reset & start; if 'paused' resume. Pause/Resume toggles. Restart always resets to a fresh running game.

Rendering: draw grid, food (circle), snake (rounded rects, head different color), overlay text for states (Ready, Paused, Game Over, You Win) drawn as DOM overlay or on canvas. I'll draw on canvas with translucent veil.

Also prevent arrow keys scrolling: preventDefault on ArrowUp/Down/Left/Right and Space when handled, always for arrows regardless of focus.

Add touch/wrap UI? Not needed. Maybe add note about WASD? Keep to arrow keys as required (I'll also support WASD optionally... The spec says use arrow keys; adding WASD is harmless. I'll include it but display arrow keys. Actually keep minimal ambiguity — I'll support arrows plus WASD, displayed controls mention arrows.)

Let me also handle high-DPI: canvas width = 480 * dpr, style width 480px. And responsive scaling via CSS max-width 100%.

Let's write the file.

Score display: current score, and best score (in-memory, no localStorage to avoid network? localStorage is fine locally but sandboxed environments may throw; I'll use try/catch). Keep simple: just show Score and Length maybe.

Let me write it.

Also need a food "spawned in another unoccupied cell" — choose random from free cells list to guarantee uniform and unoccupied.

Also handle when board full at start? not needed.

Game loop: requestAnimationFrame with accumulator; step interval ~100ms, maybe speed up slightly with score (min 60ms). Keep constant-ish: interval = max(60, 110 - floor(score/5)*5). Fine.

Write the code.

Now let's run in the browser and check.

It renders. The ready overlay shows "Snake / Press Start or Enter" — good, though the "Restart (R) to play again" line on the ready screen is a bit odd. Let me fix overlay so the ready screen shows a different third line.

Also the keys layout in "How to play" is a bit off (grid arrangement shows ↑ ← on row 1, ↓ → on row 2). My CSS intended a cross layout: 4 kbds in a 3-col grid; nth-child(1) col 2, nth-child(4) col 2 — but nth-child(2) is in row 1 col 1... Actually with 3 columns: item1 (col2 forced, row1), item2 auto-placed... it went row1 col3? Hmm, output shows ↑ and ← on row 1, ↓ and → on row 2. Let me just simplify: use explicit grid areas.

Let me now test behavior with the browser tool. First check the game logic via console-driven steps. The browser tool doesn't have an "evaluate" action though — only reload/inspect/screenshot/motion/click/drag/key/type/scroll. Hmm, no JS evaluation. So I need to verify visually via screenshots and key presses.

I can click Start, press arrow keys, take screenshots, and read the DOM (score/length/status text). The inspect action returns DOM text, which includes score and length — great for verification.

Let me also verify reversal ignoring: I can't easily inspect internals without eval. But I can test observable behavior: press Up then Left quickly (before next step) — the second should be ignored if it reverses... Actually to test reversal: while moving right, press Left → ignored (no reversal). Then snake keeps moving right. Hard to observe directly but a rapid Up then Left should turn up then left.

Better: I could write a separate headless test using node to simulate the logic? Not necessary but a good verification. Actually, I can extract the script and run the game logic in node with a stub canvas to test the rules thoroughly. That's a nice approach: use jsdom? Not available. I could stub document/window minimally. That's some effort but feasible.

Alternative: use the browser's key actions and screenshots. Let's do the interactive pass first.

Let me fix the keys CSS and the ready overlay line, then test.

Also note: `if (state !== READY && state !== RUNNING && (message || state === READY))` — that condition's second clause never triggers when first is true... it's fine because the else-if handles READY. Simplify.

Also a potential issue: on OVER/WON, arrow keys are prevented from scrolling — good.

Another: `startBtn.disabled = state === RUNNING` — during pause, Start says "Resume". Fine.

Let me also double-check the frame loop: `rafId = requestAnimationFrame(frame); if (state !== RUNNING) { rafId = null; return; }` — but startLoop sets rafId and frame also sets rafId. If state isn't RUNNING at first frame, rafId set to null while a rAF is pending — the pending callback will still run once and return early (setting rafId=null again). Minor leak but harmless. Actually there's a bug: startLoop checks `if (rafId !== null) return;` — if a stale pending frame exists with rafId null, we'd get two chains. Let's restructure: use a single persistent rAF loop that always requests the next frame and only steps when RUNNING. Simpler and no double-chain risk.

Let me rewrite the loop:

```
function frame(ts){
  rafId = requestAnimationFrame(frame);
  if(state !== RUNNING){ lastStep = 0; return; }
  if(!lastStep) lastStep = ts;
  var dt = ts - lastStep; lastStep = ts;
  acc += dt;
  ...
}
```
And start once at init, never cancel. Then pauseLoop only resets timing. That removes double chains.

Let me apply edits.

Wait, I made a mess with the overlay function: I renamed the signature to `function overlay(title, sub, third) {` and then also created `function overlayBody(title, sub) {` from the old body start. Let me read the current draw/overlay section to fix.

There's a duplicate: line 556 `function overlay(title, sub, third) {` followed by an unclosed body? Let me read lines 545-580.

Fix: remove the stray `function overlay(title, sub, third) {` line and rename overlayBody to overlay.

Also for the WON state, message is "You win! Board full." which duplicates. Let me change win() message to "Board completely filled". Also the `if (state !== RUNNING) { rafId...}` — I removed rafId usage but the variable is still declared; fine.

Also startLoop/pauseLoop now just reset timing; but pauseLoop is called in win/gameOver — fine.

Now let me also verify: in `start()`, when state is READY, we set state=RUNNING and startLoop() (resets lastStep). Good.

Let me run a headless logic test in node to verify the rules thoroughly. I can extract the script and stub DOM. Let's do that — it's a good verification of reversal ignoring, tail-follow, win, etc.

Approach: write a node test that reads index.html, extracts the <script> content, and evaluates it with stubs for document/window/canvas ctx/requestAnimationFrame. Then use window.__snake hook to drive steps.

Stubs needed:
- document.getElementById returns fake elements with textContent, setAttribute, addEventListener, style, disabled, tagName.
- canvas.getContext("2d") returns a proxy object with no-op methods and settable props.
- window.addEventListener, requestAnimationFrame no-op.
- devicePixelRatio.

Let me write it.

The reversal-into-neck check works: queue after up,left,right,down = [up,left,down]? Wait, "right" was rejected (reverse of left ✓), "down" accepted because it's relative to last queued = left, and down isn't opposite of left ✓. So queue = [up,left,down]. Correct.

Hmm, but note: after up then left, then down — down is a valid turn from left. Good.

Now test: eating food grows + respawns in free cell; wall death; tail-follow allowed; self-collision death; win state. Let me write a more thorough test by manipulating internals — I don't have setters. I can test by simulating: place food manually? Not exposed. Let me add a test hook? Better: I can test tail-follow and wall-hit by driving steps.

Simplest: drive the snake to run into the wall and check state becomes 'over'. Then test tail-follow: create a scenario where snake turns into a tight loop (a 4-cell loop) — with length ≥ 5, moving right, then up, left, down: the down move targets the tail cell which vacates → allowed. Let's simulate: snake length 3 initially; after eating it grows. Let me just run a spiral-driving script: repeatedly turn clockwise in a small square and see if it dies or survives.

Actually a cleaner test: I'll add a hidden test hook to __snake allowing me to set snake/food for verification. That's extra API surface in the shipped file... acceptable? It's a debug hook; I already expose __snake. I'll add `set` helpers: `debugSet(snakeArr, dirName, food)`. Hmm, keeping it is fine but let me instead do the tests through driving real steps.

Test tail-follow: start game, grow snake to length ≥5 by teleporting? Without setters I'd need many food eats. Alternatively test the collision loop logic directly: simulate a snake where head moves into tail index. I can test by using the exposed `turn`/`step` with a longer snake obtained by eating. To eat reliably I'd need to know food position and steer there — doable with a pathfinding loop: greedy step toward food avoiding walls/self. Let me write a driver in node: while state running, choose direction toward food using simple greedy (prefer axis with larger delta, avoid immediate reversal and avoid cells occupied by body except tail), step manually. This tests eating, growth, score, food-free-cell invariant, and eventually long snake/tail-follow behavior.

Let me do that with a cap of, say, 5000 steps and report max length and any invariant violations (food on occupied cell, food off board, duplicates in snake).

Also test win: greedy driver may fill board? Unlikely with greedy. Instead, test win by making the snake fill the board: I could set up a serpentine path driver that eats all food — with greedy-follow-serpentine it's plausible but complex. Alternative: verify win logic by reasoning + a targeted unit test of placeFood when free.length===0. I can simulate: drive snake to length 400? Hmm.

Better: add a debug hook `__snake.debugFill(n)` that grows the snake artificially for testing? That's shipping test code. I think a small, honest approach: write the serpentine autopilot that follows a Hamiltonian-ish cycle (snake covers board in a boustrophedon path). With food placed randomly, following the Hamiltonian cycle of a 20x20 board guarantees eating all food and eventually filling the board (classic snake perfect strategy uses cycle with shortcuts, but pure cycle-follow works: it fills the board and wins). Implementing a cycle follower: precompute the boustrophedon cycle path over all 400 cells, at each step choose direction that follows the cycle from the head. Since the snake follows a Hamiltonian cycle, it never collides with itself (tail is next in cycle) and it will eventually reach every food. Wall hit never happens. This tests win state and tail-follow allowance too.

Boustrophedon cycle on even-width grid: columns 0..19, rows 0..19. Path: go right along row 0 from x=0..19? Standard cycle: start (0,0), go down column 0 to (0,19), then right to (1,19), up column 1 to (1,1)... hmm need a proper cycle. Classic: for a grid with even number of rows: 
- Path: (0,0) → (1,0) [row 0 rightwards] ... Actually simplest known Hamiltonian cycle on even-row grid: go along row 0 from x=0 to x=W-1, then serpentine down columns... Let me construct:

Use cycle: for y in 0..H-1, for x in ... hmm. Let me define: 
cycle order: start at (0,0). Move right along the top row to (W-1, 0)? Then serpentine: from (W-1,0) go down to (W-1,1), left to (1,1), down to (1,2), right to (W-1,2)... using columns 1..W-1 serpentine for rows 1..H-1, then finally at (1,H-1) or (?,H-1), then go left to (0,H-1) and up column 0 back to (0,0). 

So: column 0 is reserved for the return path (going up from (0,H-1) to (0,0)). Rows 1..H-1 serpentine across columns 1..W-1. Since H-1 = 19 rows, odd number... let's check: serpentine over rows 1..19 in the sub-board columns 1..19 (19 wide, 19 tall). For a serpentine covering all cells of sub-board: row1: left→right (x=1..19), then down to row2: right→left (x=19..1), etc. Row 19 (odd index counting from 1: rows 1..19, that's 19 rows; row 19 is the 19th, odd → direction left→right? Let's compute: row1 L→R ends at x=19; row2 R→L ends at x=1; row3 L→R ends at 19; ... odd rows end at x=19, even rows end at x=1. Row 19 (odd) ends at x=19. Then we need to get to (0,19) and go up column 0. But ending at (19,19) — need to travel left along row 19 to (0,19), but those cells (1..19,19) were already visited in row 19 traversal. Conflict.

Fix: make the last row traversed only from x=19 down to x=1 and then... Standard trick: reserve column 0 for return, and serpentine rows 1..H-1 over columns 1..W-1 such that the final cell is (1, H-1), then step to (0,H-1), then up column 0 to (0,0). Final cell (1,H-1) means last row traversed R→L ending at x=1 → row H-1=19 must be even-indexed in the sequence starting row1 L→R: rows 1,3,5... L→R; rows 2,4,... R→L. Row 19 is odd → L→R ending at x=19. Not what we want. So instead start row1 as R→L: (19,1)→(1,1)? But we need to enter the sub-board from (0,0)... 

Alternative simpler: reserve the return column and start the cycle at (0,0)→(0,1)? Let me just define the cycle explicitly and verify Hamiltonian-ness programmatically in the test (check 400 distinct cells and consecutive adjacency + closing edge). I'll generate: 
path = []
// down column 0: (0,0),(0,1),...,(0,H-1)
// then row H-1: from x=1..W-1? then up... 
Hmm let me think of the classic: for even W (width), serpentine by columns:
- Start (0,0). Go right along row 0 to (W-1,0)? 

Let me try: cycle = 
1. (0,0) → down column 0 → (0,H-1)  [H cells]
2. then from (0,H-1) serpentine rows H-1 down to row 1 across columns 1..W-1:
   row H-1: x=1..W-1 (rightwards), end (W-1,H-1)
   row H-2: x=W-1..1 (leftwards), end (1,H-2)
   ... each row covers W-1 cells.
   Number of rows in this serpentine: rows 1..H-1 = H-1 = 19 rows. Last row is row 1. Direction: row H-1 (index 19 → 1st in list) rightwards; row 18 leftwards; ... row y direction depends on (H-1-y) parity: even → rightwards, odd → leftwards. For y=1: H-1-y = 18 → even → rightwards, ending at (W-1,1) = (19,1).
3. Then from (19,1) go up to (19,0), and row 0 from x=19 down to x=1 → (1,0), then left to (0,0) closing the cycle. But row 0 cells x=1..19 need to be included: step 3 covers (19,0) then (18,0)...(1,0) — wait, (19,1)→(19,0) then leftwards along row 0 to (1,0), then (1,0)→(0,0) closes. 

Total cells: column 0 has H=20 cells (y=0..19). Serpentine rows 1..19 over x=1..19: 19*19=361. Row 0 over x=1..19: 19. Total = 20+361+19 = 400 ✓. All distinct? Column 0 all rows; rows 1..19 x≥1; row 0 x≥1. Yes distinct. Adjacency: (0,H-1)→(1,H-1) ✓ adjacent. Serpentine row transitions adjacent ✓. Last serpentine cell (19,1) → (19,0) ✓. Then row 0 leftwards to (1,0) → (0,0) ✓ closing. And (0,0)→(0,1) ✓ start. Great, it's a Hamiltonian cycle.

Now verify direction of row 1: rows list = [19,18,...,1], index i (0-based) = 19-y. Direction rightwards if i even. For y=1: i=18 even → rightwards → ends at x=19 ✓. 

Now the autopilot: at each step, the head must move to the next cell in the cycle. But the snake's initial position isn't on the cycle in cycle order... any cell is on the cycle, so just compute next cell in cycle from head and turn accordingly. Since the snake body initially occupies consecutive cells moving right (mid-1,mid),(mid,mid),(mid+1... wait head at (10,10), body (9,10),(8,10). Are these consecutive along the cycle? Not necessarily, but following the cycle is safe as long as the body cells lie "behind" the head in cycle order... Not guaranteed initially, but transient collisions could kill it. Risk: head moves to next cycle cell; if that cell is occupied by body (because body isn't aligned along cycle), we die. Initial body: (10,10),(9,10),(8,10) — cycle order: y=10 row serpentine; row 10: i = 19-10 = 9 odd → leftwards, so cells in cycle order go (19,10)...(1,10)? Wait row 10 is in the serpentine rows (1..19) covering x=1..19. Direction leftwards means cycle order: (1,10) first? For leftwards rows, the traversal starts at x=19 and ends at x=1. So cycle order within row 10: (19,10), (18,10), ..., (1,10). So (10,10) → (9,10) → (8,10) is exactly forward in the cycle! And the body occupies (10,10) head, (9,10), (8,10) — those are the cells ahead in the cycle, meaning the head would move into (9,10) which is its own neck → collision. Hmm. But the tail (8,10) vacates... (9,10) is body index 1 → death.

So I need to reverse: the body occupies cells behind the head in cycle order for safety. Here body is ahead. So instead let the autopilot initially just drive forward until the body is "behind" the head in cycle order. Simpler: start the snake facing left in the test? Or just let the autopilot: if the next cycle cell is occupied by own body (not tail), then skip a step (move forward in current direction) — risky.

Alternative simpler win test: just verify the win logic by a targeted unit test — I can call the internal placeFood path indirectly... Hmm.

Alternative: use a different autopilot: BFS shortest path to food avoiding body (except tail), move along it. This grows the snake and can play quite long, but filling 400 cells with BFS-greedy usually self-traps.

Practical compromise: test the win condition by directly evaluating the logic in isolation: extract the source and check that when snake.length reaches 400, win() is called (code path: `if (snake.length >= CELLS*CELLS) { food=null; win(); }`) and placeFood's empty-free-cells branch. I could also test with a smaller board by overriding CELLS — not exposed.

Actually, I can make the cycle autopilot work: the issue is only the initial 3-cell orientation. I can first take one manual step right (away) and then... let's think: after stepping right, head at (11,10), body (10,10),(9,10) — still body behind head in the "leftwards cycle" sense: cycle order goes ... (12,10),(11,10),(10,10),(9,10)... so head at (11,10), next cycle cell is (10,10) = body. Always the case because the body trails to the right of the head in x, and the cycle in row 10 goes in decreasing x. So following the cycle = reversing into itself. Instead, follow the cycle BACKWARD: previous cell in cycle = (12,10), which is forward of the head's current direction (right). So drive the snake following the cycle in reverse direction! Then the head's next cell is (12,10) and body is behind. Following the cycle in reverse is also a valid Hamiltonian cycle traversal (reverse of a cycle is a cycle). And the body cells (10,10),(9,10) are behind the head in reverse-cycle order ✓.

So: next = prevInCycle(head). And direction deltas computed accordingly. But careful: the head must currently be moving in a direction consistent; turn() only accepts perpendicular turns, not reversal. prevInCycle(head) from (11,10) is (12,10) → delta (+1,0) = current dir right → sameDir → turn() drops it (fine, dir already right). Good — turns are only needed at cycle corners, and cycle never reverses (no 180°), so turn() will accept them.

Let me implement: build cycle array `cyc` of 400 cells in order, map key→index. Each step: target = cyc[(idx(head)-1+400)%400]; delta = target - head; call G.turnDir(delta) — my exposed turn only takes names; I can map delta to name. Then G.step(). Repeat until state != running or 2000 steps; report final length/score/state. This exercises eating, growth, food invariants, tail-follow (in reverse-cycle, the tail is at prev... the head moving to target which is where the tail will vacate — allowed case happens), and win at 400.

Also need to check food invariant each step: food is unoccupied, on board, integer.

Let me write this test.

The autopilot ran 6000 steps, snake length 31, score 28 — it's looping around the cycle but food at (0,19)... wait, it should eat every food since it covers all cells. Length 31 after 6000 steps means it ate only 28 foods?? That means it's not traversing the whole cycle — probably because when food is eaten, the snake grows and the head... hmm. Oh I see the bug: following the cycle in reverse means the head visits cells; but the initial condition: the head's next target is (12,10)... wait, actually the issue is my turn() drops "same direction" — fine. But there's a subtler problem: when the head reaches a corner, the turn is queued and applied on the next step. Since I call turn then step immediately, and the queue is applied at the start of step, that's fine.

But why only 28 foods in 6000 steps? A full cycle lap is 400 steps and should eat every food (food is somewhere on the cycle). Unless the snake keeps dying... no, state running. Unless it's not following the cycle — maybe the queue has stale turns. Let me debug: print head positions over time and check whether the head follows the reverse cycle.

Possible bug: `G.turn` is `function (name) { turn(DIRS[name]); }` — if name is undefined (delta 0, i.e., target === head?) no. Hmm.

Wait — maybe the issue: when the snake eats food, the food respawns randomly, possibly right behind the head, and the cycle-follow continues. That's fine, it should still eat it on the next lap.

Let me instrument: track head sequence and count how many distinct cycle indices visited over 400 steps.

Another possibility: my reverse-cycle target computation gives a delta that equals the reverse of the current dir at some points... e.g., at the transition from column 0 (moving down) to row 19 (moving right): head at (0,19), prev in cycle = (1,19)? Let's see cyc order: index 19 = (0,19), index 20 = (1,19). prev of (1,19) is (0,19). So when head is at (1,19), target = (0,19) → delta (-1,0) left. And when head at (0,19), target = prev = (0,18) → delta (0,-1) up. So reverse traversal: column 0 traversed upward, rows serpentine... consistent.

Hmm, so why so few foods? Let me actually check: does the head revisit? Let me log positions for the first 60 steps and see the pattern, and also check the dir/queue.

Actually! I bet the problem is that the snake's body is longer than the tail-vacating assumption at the very start: initial head (10,10) moving right, body (9,10),(8,10). Reverse-cycle target from (10,10) is (11,10) — that's fine. But wait, G.start() sets state running; the first step I compute target from head (10,10) → prev in cycle. Row 10 direction: i=(19-10)=9 odd → leftwards, so cyc order in row 10 goes x=19,18,...,1. So prev of (10,10) in cycle = (11,10) ✓ delta right ✓ same as dir → dropped, step moves right to (11,10) ✓. Consistent.

So the head should trace the reverse cycle. Let me verify empirically with logging.

The trace shows the head is following the reverse cycle correctly, but note the turn lag: at "19,10->19,11 dir:{1,0}" — the turn to down is applied at the next step (when head is at 19,10, we compute target 19,11 and turn down, then step → head moves down). Yes, correct.

But wait: "1,11->1,12 dir:{-1,0}" then next trace shows head at 1,12 with dir down. Hmm, but the turn from left to down happens at (1,11) → target (1,12). Good.

So the head follows the cycle. But then why only 31 foods in 6000 steps? 6000 steps ≈ 15 laps of 400 → should eat ~15 foods minimum... Actually each lap eats exactly 1 food (the food is eaten when the head reaches it, then a new food spawns somewhere; the head continues and will reach the new food within the same lap if it's ahead, or next lap). So ~15 laps → ~15-31 foods. Consistent! Score 31 in 6000 steps ≈ 2 laps/food. That's expected behavior for cycle-following, not a bug.

So to reach a win I'd need ~400 foods × ~2 laps = ~160,000 steps. That's fine in a headless test — steps are cheap (each step is O(400) work → 160k*400 = 64M ops, a few seconds). Let me run the loop until state != running with a cap of 400,000 steps and see if it wins. That will thoroughly test growth, food invariants, tail-following, and the win state.

Note: my autopilot doesn't call `draw`, so no canvas cost. Let's run it.

OOM — the test itself leaks because `G.snake` getter maps to a new array each call, and `G.snake.some(...)` per step is O(n) allocations... but that shouldn't leak 2GB. Hmm, `idx.get(h.x+','+h.y)` creates strings — GC should handle. Something is retaining memory. Possibly my Proxy ctx2d `set` stores everything into the target object — draw() isn't called during steps... Actually step() calls draw()! Yes, `step()` ends with `if (state === RUNNING) { syncUI(); draw(); }`. draw() calls ctx methods; my Proxy stores props. Also `occupiedSet()` creates objects each placeFood — fine.

The leak: probably the Proxy's get returns a new function `noop` each time — no. Hmm, `ctx.setTransform(dpr,0,0,dpr,0,0)` fine.

Actually maybe the leak is in the real game: `requestAnimationFrame` stub is noop, so no loop. Hmm.

Wait — maybe it's an infinite... no, it ran 500k steps? It OOM'd. Let me count: what's allocating per step and never released? `G.snake` getter creates a new array of new objects each access — I access G.snake up to 3 times per step, plus inside step... these are garbage-collectable.

Unless... the Proxy target `t` accumulates: `set` handler sets t[k]=v — only a handful of keys.

Hmm, maybe the OOM is from `message`? no.

Let me check: does `draw()` push anything to an array? No.

Could the leak be in my test's `NAME` lookups? No.

Let me investigate with a smaller cap and measure heap, e.g., 50k steps with --max-old-space-size and log memory. Actually maybe the issue is that the game logic itself leaks: `queue` bounded to 3. `snake` bounded to 400.

Oh! I see it — in the test, `while(G.state==='running' ...)` — G.state getter is fine. Hmm.

Let me just test with a cap of 20000 steps and print memory to see growth rate.

Straightforward: without turning, the snake hits the right wall → "over". Good, that verifies wall death. No memory growth here.

So the OOM in the previous test must come from my test loop... `idx.get(h.x+','+h.y)` — h from G.snake[0] getter (new array each time). Hmm, that's collectable.

Wait — maybe the game never ends and the loop ran 500k steps, and each step allocates ~? 500k steps × (snake array of up to 400 objects ×3 getters) = lots of short-lived garbage but GC handles it. Unless... `NAME[(t.x-h.x)+','+(t.y-h.y)]` returns undefined when target == head? No.

Hmm, actually: `G.turn(undefined)` → `turn(DIRS[name])` where name is undefined → DIRS[undefined] → undefined → `if(!nd) return;` fine.

Let me instrument the win test with periodic memory logs and a smaller cap to find where it blows up.

Actually — I bet the real culprit: when the snake dies (state='over'), my loop `while(G.state==='running')` exits... fine.

Let me run the win test with cap 50000 and memory logging.

Still OOM at 60k steps. Something is genuinely leaking or infinitely recursing. Let me add progress logging every 5000 steps with memory, to see.

Possible culprit: `draw()` → `ctx.fillText` etc. via Proxy — the Proxy `get` returns `noop` for unknown keys, but for `canvas` key... fine.

Hmm wait: `ctx.setTransform` etc. But there's `rr()` which uses ctx.beginPath, moveTo, arcTo, closePath, fill — all noop.

OH. I see it! In `frame()` I call `requestAnimationFrame(frame)` at the top — in the game code, `requestAnimationFrame` is the noop param passed in. But at init I call `requestAnimationFrame(frame)` — noop. Fine.

Let me look for recursion: `step()` → `win()` → `syncUI(); draw();` → nothing recursive. `placeFood()` → `win()` → ... `win()` doesn't call placeFood. OK.

Hmm, but `gameOver()`/`win()` call `pauseLoop()` and `draw()`. draw() → overlay(). Fine.

Let me check `step()`: after `if (snake.length >= CELLS*CELLS) { food=null; win(); syncUI(); draw(); return; }` — fine.

Let me just log.

No progress output at all before OOM (2000 steps not reached!). So it OOMs within the first 2000 steps of this driver. But the earlier test ran 6000 steps fine. Difference: this one logs memory... no. The earlier test_snake.js ran 6000 steps and completed. Hmm, but earlier test_win.js with 500000 OOM'd, and with 60000 OOM'd. Now 20000 OOMs before the first log at 2000.

Wait — maybe the OOM happens during `G.start()`? No, earlier test worked.

Difference from test_snake.js: it had `checkFood`/`checkBody` with try/catch... and the loop broke? No, it completed 6000 steps.

Hmm, actually in this script the memory log uses `mem()` only at 2000-step intervals. It OOM'd before any output. Something is different... `const idx=new Map(...)` same.

OH WAIT. I see it: `const h=G.snake[0]` — G.snake getter returns mapped array. `idx.get(h.x+','+h.y)` — if head is not in idx (impossible) → i undefined → `cyc[(undefined-1+400)%400]` = cyc[NaN] = undefined → `t.x` throws TypeError. That would throw, not OOM.

So where's the OOM? Let me test step by step with output flushing. Maybe the issue is that stdout is buffered and lost on abort! Yes — console.log output may be lost when the process aborts (stdout to a pipe is async-buffered). With `| tail -20`, output is piped → buffered → lost on crash. That explains "no progress output". So the loop probably ran far.

So the OOM is real but happens somewhere. Let me write logs to a file with fs.writeSync (synchronous) to see progress.

My sed produced broken syntax. Let me just rewrite that line properly with a python or edit the file directly.

Interesting! A SyntaxError from my broken sed — and note the earlier OOM runs used the *previous* version of test_win3.js? No — the OOM run happened with the broken sed already applied? Let me check order: I ran sed then `node /tmp/test_win3.js 2>&1 | tail -20` → that had the broken syntax → should have been a SyntaxError, not OOM! But it showed OOM... because the OOM output shown was from... hmm, confusing. Actually the sed and node ran in the same command; the output showed OOM messages. That means the file was valid then? The grep output shows the broken line — so node should have failed with SyntaxError. Unless the OOM came from... whatever.

Wait, maybe the OOM output was from the previous command's leftover? No.

Hmm, actually the sed replacement: `s|'state',G.state);|'state',G.state+'\\n');|` — the resulting line is broken. So node would exit with SyntaxError quickly. But we saw OOM. Strange... unless `node --stack-size` ... no, that was the prior command.

Whatever. Let me rewrite the test file cleanly with the write tool, using appendFileSync for progress.

I made a typo: `{ x, y: 0 }` should be `{ x, y: 0 }` — actually that's valid: shorthand x plus y:0. Fine.

Run it.

The full-game test passes: 38,703 steps, snake reached length 400, score 397, state = 'won', food = null, no food invariant violations, no memory leak. So the earlier OOM was caused by my broken test scripts (probably the earlier `while(G.state==='running' && steps<500000)` with `console.log` piped... hmm, whatever — actually earlier test_win.js had `G.turn(NAME[...])` where NAME could be undefined and turn(undefined→DIRS[undefined]=undefined) fine... The difference: earlier test used `G.snake.some` inside the loop AND `checkFood` — no. Never mind, the earlier OOM was likely stdout buffering through `tail` on a pipe combined with... no. Anyway, this run is clean and proves the win state works.

Wait, actually earlier test_win.js differed: it computed `t=cyc[(i-1+400)%400]` — same. And it broke on bad food. Hmm, one difference: earlier scripts had `if(f && (...))` same. Odd. Possibly the OOM came from console.log buffering into a pipe with huge... no logs. Whatever — the current test is authoritative and passes.

Now let me also verify:
1. Wall death ✓ (test_mem showed state 'over' after hitting right wall).
2. Self-collision death: drive a spiral to hit own body.
3. Tail-follow allowed: the cycle-follow test implicitly relies on it (head moving into the cell that the tail vacates when the snake is long? Actually in cycle-follow, the head's target is always the cell right before it in cycle order, and the tail is somewhere behind — for a snake of length L following a cycle of 400, the tail is L cells behind the head in cycle order... the head moves to the cell before the head, which is where... hmm, in reverse-cycle traversal, the body occupies cells *after* the head in reverse order, i.e., the tail is the farthest. The cell the head moves into is the next in reverse cycle, which is the cell the tail occupied L steps ago... For L=400 (full board) the head's target = tail cell exactly. But at 400 the game ends. Anyway, tail-vacating is exercised: when the snake is long, the head's target cell is occupied by the tail only when L=400. Hmm, so maybe not exercised.

Let me write a targeted test for tail-follow: I need control over the snake. Since I can't set internals, I'll test via a scenario: build a long-ish snake via the cycle driver, then... complicated.

Alternative: test the collision rule logic directly by constructing a mini harness that reimplements? No — better to test the real code path. 

Idea: A U-turn trap: with a snake of length ≥5, moving right, turn up, left, down — the "down" move enters the cell that was the tail at the time of the "left"? Let's simulate a 5-long snake: cells (in order head..tail): (5,5),(4,5),(3,5),(2,5),(1,5) moving right. Turn up: head (5,4); body (5,5),(4,5),(3,5),(2,5) [tail (1,5) popped]. Turn left: head (4,4); body (5,4),(5,5),(4,5),(3,5). Turn down: head (4,5) — is (4,5) in body? body before removal: (5,4),(5,5),(4,5),(3,5) — (4,5) is index 2, not the tail → death. Right, a 90-90-90 turn into a 3x3 box requires length ≥ 5 to be safe: for the classic "chase your tail" you need a loop where the head enters the tail cell. With a square loop of side 3 (perimeter 8 cells), a snake of length 5+ can loop: head goes around the 8-cell loop; the tail is 4 cells back → moving into the tail cell that vacates is allowed only if the body doesn't occupy the target. Let's simulate: snake length 5 on loop of perimeter 8: positions along loop indices head=0, body=7,6,5,4 (going backwards). Target = index 1 (moving forward)... hmm, wait: if the head moves forward along the loop, the cell ahead (index 1) — is it occupied? Body occupies 7,6,5,4 → index 1 free. Next step: head=1, body=0,7,6,5. Then head=2, body=1,0,7,6. head=3, body=2,1,0,7. head=4, body=3,2,1,0. head=5, body=4,3,2,1. ... head=7, body=6,5,4,3. head=0 (target 0 — body has 7? Let's recount: when head=6, body=5,4,3,2; target 7 free. head=7,body=6,5,4,3; target 0 free. head=0,body=7,6,5,4; target 1 free. So with length 5 on perimeter 8, it never enters an occupied cell. It never enters the tail cell exactly either... at head=7→target 0, tail is 4. Hmm.

To test the specific "moving into tail cell that vacates is allowed" rule, I need length such that target == tail. On a loop of perimeter P with length L, the head's target is L cells behind... The tail is at loop index (head - L) mod P. Target = head+1. Equal when L ≡ -1 mod P, i.e., L = P-1. So a snake of length 7 on a perimeter-8 loop: head's target = tail cell → allowed (non-growing step). If we incorrectly disallowed it, the game would end.

So: get a snake to length 7 and drive it around a 3x3 loop. That requires eating 4 foods, which I can't force without setters... but the cycle driver eats food naturally. Hmm, but I'd need to then steer into a small loop.

Alternative simpler approach: expose a test-only setter in __snake? I already expose internals for checks; adding a `__snake.debugSet(snakeArr, dirName, food)` would let me construct exact scenarios. Is it acceptable in the shipped file? It's a hidden debug hook, harmless. But it adds surface. Alternatively, I can verify the rule by reading the code (the `if (!eats && i === last) continue;` line) — clear and reviewed.

Middle ground: write a separate node test that patches the source code before eval — e.g., replace `reset(READY);\n  requestAnimationFrame(frame);` with a version that lets me set state. Actually easier: I can inject a helper by string-replacing in the *test copy* of the code: add to the __snake object a line `dbg: function(s,d,f){ snake=s; dir=d; food=f; }`. In the test I can do `code.replace('start: start, pause: pause', 'dbg:function(s,d,f){snake=s;dir=d;food=f;},start: start, pause: pause')`. That keeps the shipped file clean while testing the real logic. 

Let me do that: 
Test A (tail vacate allowed, non-growing): snake = 7 cells forming part of a 3x3 loop perimeter, food placed far away (not on the target), dir set; step around the loop several times → should stay alive.
Test B (tail NOT allowed when growing): place food exactly on the tail cell, snake length 7 on loop, head target = tail cell with food there → eating grows → collision with the (now non-vacating) tail → over.
Test C (self-collision death): snake length 5 moving right, turn up, left, down → hits body index 2 → over with "Bit yourself".
Test D (restart resets): after some steps and growth, restart → len 3, score 0, state running, food on a free cell.
Test E (pause/resume): pause → state paused, step() no-ops (my step guard: `step: function(){ if (state===RUNNING) step(); }`), dir preserved.

Let me write these.

For test A: define loop cells (perimeter of 3x3 box from (2,2) to (4,4)):
perimeter order: (2,2),(3,2),(4,2),(4,3),(4,4),(3,4),(2,4),(2,3) → P=8. Snake length 7: head = loop[0]=(2,2), body = loop[7],loop[6],...,loop[1]? Body follows behind head in traversal direction: if moving forward (head→loop[1] next), body = loop[7],loop[6],loop[5],loop[4],loop[3],loop[2] (6 cells) → total 7. Then head's target loop[1] is free. After step: head=loop[1], body=loop[0],loop[7],...,loop[3]. Target loop[2] free. ... eventually head=loop[0] again with body loop[7..2]? Let's see: at some point target = loop[k] where k = head index+1, and body = previous 6 cells → target is free always. Hmm, so target==tail never happens in steady state with L=P-1? Let's check: L=7, P=8. head at index h, body at h-1,...,h-6 (mod 8). Target = h+1. Tail = h-6 = h+2 mod 8. So target h+1 ≠ tail h+2. Hmm. So the head never enters the tail cell exactly in steady state.

For target == tail: need h+1 ≡ h-L+1 mod P → L ≡ 0 mod P... wait tail index = h-(L-1). Set h+1 ≡ h-(L-1) mod P → 1 ≡ -(L-1) → L ≡ -1+... let me redo: 1 ≡ -(L-1) mod P → L-1 ≡ -1 mod P → L ≡ 0 mod P → L = P = 8. But L=8 means the snake fills the loop entirely — then head's target is the tail cell (which vacates) → allowed! That's exactly the classic "snake coils tightly and keeps moving". So test A: snake length 8 = full 3x3 perimeter, food elsewhere, step 8+ times → must survive (each step moves into the vacated tail cell). If the rule were wrong, it dies on the first step.

Great, that's a clean discriminating test. And test B: same but with food on the tail cell → growing → collision → over.

Let me write it.

Note: score doesn't reset in restart? My reset() sets score=0 ✓. But `best` persists.

Also test C: `G.dbg` sets state='running' — good.

One issue in test A: LOOP with dir NEXTDIR[0] = right at head (2,2) → target (3,2) which is body index 7? No: body = LOOP[7],LOOP[6],...  wait I set snake = LOOP.map(...) in order, so snake[0]=LOOP[0]=(2,2) head, snake[1]=(3,2), ..., snake[7]=(2,3). But the body must trail *behind* the head, i.e., snake[1] should be the cell the head came from = LOOP[7]=(2,3) if moving right. I passed snake in loop order, so snake[1]=(3,2) is the *neck* ahead of the head — that's an invalid configuration (moving right into its own neck).

Fix: snake should be [LOOP[0], LOOP[7], LOOP[6], ..., LOOP[1]] for head moving forward to LOOP[1]. Let me define snake = [LOOP[0]].concat(LOOP.slice(1).reverse()).

Then head=LOOP[0]=(2,2), body=LOOP[7]=(2,3), LOOP[6]=(2,4), LOOP[5]=(3,4), LOOP[4]=(4,4), LOOP[3]=(4,3), LOOP[2]=(4,2), LOOP[1]=(3,2). Target = (3,2) = LOOP[1] = tail index 7 → the vacating tail → allowed ✓. 

For test B: food on the tail cell = LOOP[1] = (3,2) = snake[7]. Growing → tail doesn't vacate → death ✓. So set food = LOOP[1] rather than LOOP[7].

Let me fix those.

Also NEXTDIR[0] = {1,0} right ✓ from (2,2) to (3,2).

Test D: snake [5,5],[4,5],[3,5],[2,5],[1,5] moving right; turn up → head (5,4), body [5,5],[4,5],[3,5],[2,5] (popped (1,5)); turn left → head (4,4), body [5,4],[5,5],[4,5],[3,5]; turn down → head (4,5) which is snake index 2 → death ✓.

Test F: dbg with snake [5,5],[4,5],[3,5] dir right, food far (15,15). turn('left') → reversal vs dir right → dropped. turn('down') → queued. turn('up') → opposite of last queued (down) → dropped. turn('left') → not opposite of down → queued. Queue = [down,left] ✓. Then step applies down.

But careful: after steps, does the snake hit a wall? Starting head (5,5): down to (5,6), then left to (4,6). Fine.

Test G: pause() then step() — my exposed step checks state==='running' so no-op ✓. Also the real loop won't step. Good.

Test H: dbg with head (5,5) dir right, food (6,5): step → eats → len 7, score 1; step → moves to (7,5). Then restart → len 3, score 0 ✓.

Let me apply the fixes to test A/B.

Wait, for test A: COIL's tail (index 7) = LOOP[1] = (3,2). Head (2,2) moving right → target (3,2) = tail → vacates → allowed. But my rule check: `if (!eats && i === last) continue;` — the tail is index 7 = last ✓ skipped → allowed. 

But hold on: is the target also occupied by any other cell? No.

Also test A's "coil keeps grid positions" check: after 16 steps, the snake occupies the 8 loop cells ✓ (it stays coiled).

Also NEXTDIR is unused now except index 0. Fine.

Run.

The one failure is my test's fault: after 16 steps around the loop, the coil travels — wait, head at (2,2) moving right into the tail cell... after 8 steps the coil should return to the same positions. Hmm, the result shows the snake at y=2, x=11..18 — moving right along row 2! That means the coil didn't turn; it just went straight right. Because in test A I only set the initial dir and never call turn() — the snake goes straight right along row y=2 and eventually hits the right wall at x=19... but state is 'running' and len 8, head at x=18 after 16 steps: start head (2,2) → 16 steps → (18,2). It didn't die at the wall because it stopped at 16 steps (would die at step 17).

So test A actually verified: the coil moved right, with the tail cell being vacated each step... wait, no: the snake moved straight right, so the target cell was never occupied. Hmm, that means test A didn't verify the tail-vacate rule at all!

But it did pass 8 steps... Let me redo test A properly: use the COIL and drive it around the loop with turn() calls each step (like the cycle driver). I need to turn at each corner: from head LOOP[0] moving right, target LOOP[1]=(3,2) which is the tail → allowed. After that step, head=(3,2) and dir=right; next target LOOP[2]=(4,2) → dir right, no turn needed. Then (4,3): turn down. Then (4,4): down. Then (3,4): turn left. (2,4): left. (2,3): turn up. (2,2): up. Then (3,2): turn right... 

So I need a turn schedule. Let me compute target from the loop index each step and call G.turn with the delta name. That's the right test: 16 steps around the loop, verifying it survives (tail-vacate rule) and returns to the same coil.

Test B already passed with the food-on-tail variant? In test B, I used COIL and food at LOOP[1]=(3,2) with dir right, no turn → the head moves right into (3,2) which is the tail cell and also the food → growing → must be fatal ✓. That passed and it's a valid discriminating test of the tail rule (since without the "growing" exception it would have been allowed). Good — B confirms the rule works in one direction.

Now fix A to actually turn.

Wait: the coil's head is at LOOP[0] and body occupies LOOP[7..1] (trailing backwards). Moving forward to LOOP[1] = the tail cell → allowed. After the step, head=LOOP[1], body = LOOP[0],LOOP[7],...,LOOP[2] — so the coil rotates. Good, and it stays on the loop.

But careful: my loop uses `hi = index of head in LOOP` and target = LOOP[hi+1]. Initially hi=0, target LOOP[1] ✓.

Run again.

All 23 logic tests pass, plus the 400-length win test. 

Now let's do the interactive browser verification: click Start, press arrow keys, screenshot, check DOM score/length, pause/resume, restart.

Note: the game loop uses requestAnimationFrame; the browser tool's `motion` action may capture frames. Let's do:
1. reload → screenshot (already seen).
2. click Start (button at ~517,325 in the earlier screenshot — but layout changed slightly; use inspect to find coordinates? The click action takes x,y). Let me click Start.
3. press arrow keys with a small wait? The tool has no wait; but each action presumably takes real time, so steps occur between actions (stepMs ~120ms).
4. screenshot to see snake moved/turned.
5. Press Space → paused; inspect DOM shows "Paused".
6. Click Resume → running.
7. Click Restart → length 3, score 0.

Let's go.

Keys layout fixed. Now click Start (at ~517, 325) and take a motion capture to see movement.

The click didn't register (still Ready, Start not disabled). Maybe the coordinates are off — the screenshot is 1200x800 but the page may be scaled. The DOM says "Start" button. The screenshot shows Start at approximately (858, 532)? Wait, the image is displayed at 1200x800 presumably... The image shows the Start button around x=858, y=532 in image coordinates. Hmm, but the tool says coordinates use a 1200×800 viewport, and the image appears to be 1200x800. My earlier estimate of (517,325) was based on a different scale (I misread). Let me click (858, 532).

Actually looking at the image: "Start" button center is around x=858, y=532. Yes.

Still "Ready" and the DOM text hasn't changed. Either the click isn't hitting the button, or the DOM snapshot is taken at frame 1 (+0ms) before the click effect. The reported DOM might be pre-action. Hmm, the status shows "Ready" — if the click worked, the status would be "Running" and Start disabled.

Let me try the keyboard: press Enter (my handler starts the game when not focused on a button). Use action "key" with text "Enter"? The key action takes `text`. Let me try `key` with "Enter", then screenshot.

Alternatively, the click coordinates might need to be in CSS pixels of the page (viewport 1200x800 with device scale?). The screenshot image is 1200x800 and the button is at ~(858,532) in that image. Should be right.

Maybe the DOM snapshot is captured before the click handler runs (sync). Let me take a screenshot to see the current state.

Still Ready. So the click didn't take effect. Possibly the sandbox iframe blocks clicks? Or the click coordinates are in a different space (the page might be rendered at a different viewport width, e.g., the actual page is 1200x800 but with the body centered... the screenshot shows the layout, so coordinates should map).

Let me try the `key` action with "Enter" to start.

Enter started the game: status Running, Pause enabled, Start appears dimmed (disabled). The snake is at the center with head facing right (eyes visible), food above-left.

Interesting: the snake head is at about x=500,y=348 and the body cells at 458,480 → grid-aligned, 22px spacing in the screenshot... The canvas is 480 CSS px wide displayed at ~480? The canvas element spans from ~250 to ~730 = 480px, cell = 24px. But in the screenshot the cells look ~22px apart, close enough (the screenshot may be scaled ~0.92? Actually the image is 1200 wide; if the viewport were 1280 wide, scale 0.9375 → 24*0.9375 = 22.5 ✓. That explains why my click at (858,532) missed: the click coordinate space is the viewport (1280x853?) while the screenshot is 1200x800. So multiply screenshot coords by ~1.0667. Start button in screenshot at (858,532) → viewport (915, 567).

Now let me use motion capture to verify movement and turning. First press arrow keys (Down, then Left) and use `motion` to see frames.

Let me do: key ArrowDown, then motion to capture frames.

Actually, the important checks: grid-aligned movement (visible), direction response, pause/resume, restart. Let me capture motion frames now while running.

The snake ran into the right wall (game over) — it had been running for a while between my actions (each action takes real time, ~120ms/step, 9 cells to the wall ≈ 1.1s). So the wall collision works in the browser. Good.

Note the overlay "Game over / Game over / Restart (R)..." duplicates the message. Let me improve: for OVER, sub = message ("Hit the wall" / "Bit yourself"), title "Game over". Here the message was "Hit the wall" — but the sub shows "Game over"?? Because `message` was set to... hmm, in this case the game-over came from the wall → message = "Hit the wall". But the overlay shows "Game over" as sub. That means message was empty/overwritten? Let's see: gameOver() sets message = "Game over" AFTER `message = "Hit the wall"` was set in step() then gameOver() overwrites it! Yes: step() sets `message = "Hit the wall"; gameOver();` and gameOver() sets `message = "Game over"`. Oops. Fix: gameOver() should only set message if not already set. I'll change gameOver to accept a reason param.

Now let's restart and do a proper turn test with motion capture. Press R to restart, then quickly press arrows and capture motion frames.

Let me fix the message bug first, then reload and test.

I need to finalize quickly. Let me reload and do one quick verification pass (restart, turn, pause, resume, restart), plus re-run the logic tests to ensure the message refactor didn't break anything.

Do them in parallel: run node tests and reload browser.

All logic tests pass (23/23) and full game → win state.

Now a quick browser check of pause/resume/restart. Enter (start) → Space (pause) → inspect → Space (resume) → R (restart) → inspect. Do it fast.

Running. Now press Space to pause, then Space to resume, then R to restart, checking DOM each time. Combine: I must do sequential calls. Let me press Space (pause) and check the DOM.

The snake moved (head is now at x≈500, previously 500? it moved right and the food moved? no, the food is at a different place because the game restarted with a new food... Actually the snake head is at the same spot as before; the DOM still says "Running". The Space key may not have been delivered (the tool's key name "Space" may not map). The snake appears frozen at the same position as the previous screenshot though — hmm, both show head at ~500,348. That suggests the game is paused (Space worked) but the status text snapshot was taken before the handler? The DOM says "Running" and the button still says "Pause" (not "Resume"), so pause didn't register. But the snake position is identical to the previous frame... suspicious — maybe the screenshots are taken at the same animation time.

Let me try the key with " " (space char) instead. Or click the Pause button at screenshot coords (858, 378) → viewport coords ×1.0667 ≈ (915, 403).

The game hit the wall (the snake advanced right off the board while I was clicking) — overlay now correctly shows "Game over / Hit the wall". The click at (915,403) hit the Pause button but the game had already ended (Pause disabled). So coordinates map ~1.0667× — good.

Now: press R to restart and verify length/score reset, then quickly pause/resume with the buttons.

Time is short (~4 min). Let me do: key "r" → check DOM (should be Running, len 3, score 0), then click Pause (915,403) → check "Paused"/"Resume", then click Resume → "Running".

Restart (R) worked: Running, length 3, score 0, snake back at center, new food in a free cell (different position). 

Now quickly: press ArrowDown then click Pause fast to catch "Paused". The snake has ~1.1s before hitting the right wall. Let me click Pause (915,403) immediately and check status = Paused, then click Resume.

Better: first turn Down (arrow) so it doesn't die, then pause. Two sequential calls. Let's do ArrowDown then click Pause.

It died on the wall again before the arrow key arrived (each tool call takes >1.1s of wall time, so the snake reaches the wall between actions). The pause check via keyboard/click is timing-constrained. I already verified pause/resume logic in the headless tests (test G: "paused: step is a no-op", "resumed: moves again"), and the Pause button label toggling is driven by syncUI.

Let me do one final quick attempt to see the Paused overlay in the browser: click Restart button (viewport ~ (915, 487)), then immediately click Pause (915,403). Two calls — the restart→pause gap may exceed 1.1s again. Alternatively click Restart then Pause; if it dies first, Pause is disabled.

Better idea: click Pause first? no.

Try: click Restart (915,487) → then click Pause (915,403). Even if the snake dies in between... the gap per call seemed ~1-2s. Risky but let's try once; if the status shows Paused, great.

Actually, a smarter approach: press Enter to start... same issue.

Let me just try the two clicks.

The Restart click didn't register (still Game over) — my y coordinate for Restart may be off (screenshot y=427 → viewport 427*1.0667=455, not 487). Let me recompute: screenshot→viewport scale factor = 1200/1125? Earlier: Start button in screenshot at y=325 and Pause at y=378, Restart at y=427. I clicked Pause at viewport y=403 and it did hit... hmm, did it? The status changed to "Game over" after that click, which could have been the natural death. Unclear.

Given the time limit (~2 min left), I'll stop browser poking. Pause/resume is verified headlessly (state transitions, no-op steps, resume continues) and the buttons are wired to the same functions.

Let me do a final sanity check that the file is valid (no syntax errors) — the browser loaded it fine after the last edits (the reload earlier showed the game running with the fixed overlay text "Hit the wall"), so yes, the final edits are in place and working.

One last check: the file ends properly and no leftover debug code. Run a quick grep + node syntax check.

Everything is in place. Final report.

Summary of what I checked:
- Browser: page loads with no console errors (only a sandbox iframe warning from the harness), Ready state, Start via Enter → Running with grid-aligned 3-cell snake and food, wall death overlay ("Game over / Hit the wall"), Restart via R → length 3, score 0, new food in a free cell, Running state.
- Headless (real game code driven through a debug hook): 23 assertions — tail-vacate allowed on non-growing step, fatal when growing into own tail, eat grows +1 & score +1, food respawn free/on-board, body bite death, all four walls kill, reversal dropped from the turn queue including rapid multi-input buffering, queued turns applied one per step, pause freezes steps, resume continues, restart resets length/dir/queue/score/food/state; plus a full autopilot game that filled all 400 cells → win state with food=null.

Unverified in-browser: clicking the Pause/Resume buttons (my click coordinates missed / the snake died of wall collision between tool calls) — pause/resume was verified headlessly and via the Space-key handler code, and the button label toggling logic is in syncUI. Arrow-key page-scroll prevention is implemented with preventDefault but I didn't measure page scroll (page fits the viewport anyway).

Done.