Remove the leftover automated benchmark runner from the demo

[jowens]

The demo ships with debug scaffolding, commented // Automated benchmark runner for Antigravity agent, armed unconditionally on every page load:

setTimeout(runAutomatedBenchmark, 1000);

One second after the page opens it takes the demo over for roughly 45 seconds: waits 3s, runs a sort, forces the particle count to 50000 and sorts again, then to 100000 and sorts again — moving the slider, recreating every GPU buffer, and logging progress banners to the console as it goes.

For a visitor this means the demo rearranges itself unprompted, ignores the slider, and can't be interacted with normally until the sequence finishes. It also quietly ramps a first-time visitor's GPU to 100000 particles regardless of hardware.

This is also what made the demo look broken

While investigating the black screen in #51, I measured particles confined to a horizontal band across the middle ~40% of the canvas, and flagged it as a suspected projection bug.

It isn't a bug. That band is the sort visualization working exactly as designed. applySorted sets:

destination.y = layoutInset + (hash(rank) * 0.5 + 0.25) * usableHeight

which is the middle 50% by construction, with the horizontal gradient being destination.x = layoutInset + progress * usableWidth. Any screenshot taken more than ~4 seconds after load caught the auto-sort in progress rather than the demo's resting state. So my earlier note about a 40%-height rendering bug was a misdiagnosis — the render path is fine.

Verification

Density profile of the rendered canvas, 20 vertical buckets at 1200x800:

sample	result
800ms (before the timer fires)	all 20 buckets populated
5s, runner present	buckets outside 30–70% empty
5s, runner removed	all 20 buckets populated

Regression suite 31/31 and the demo smoke test still pass.

Note

This is independent of #51 (the maxTextureDimension2D clamp). They touch opposite ends of interactive_demo.mjs and merge cleanly in either order.

🤖 Generated with Claude Code