What problem does it solve? When you build a web artifact (Three.js game, Canvas2D simulation, dashboard, UI mockup) but cannot see the screen — vision is unavailable, the model is text-only, or the run is headless — you cannot confirm whether it actually renders. This Skill replaces guessing with programmatic proof by reading the browser's real state, pixels, and errors. ## Core Features & Use Cases - Pixel-level WebGL verification: Sample canvas pixels via gl.readPixels or 2D canvas readback with preserveDrawingBuffer to prove content is drawn, not a black screen. - Error and state introspection: Hook pageerror events, expose debug handles on window, and read scene/DOM state to distinguish logic bugs from input bugs. - Syntax hunting for large scripts: Use the acorn tokenizer to locate the first unclosed brace in huge single-file <script> blobs that naive counters miss. - Use Case: A user reports your single-file Three.js game shows a blank screen. You serve it over HTTP, hook pageerror, evaluate the debug handle, sample pixels to confirm distinctColors > 1, and drive a behavior to verify the subsystem works — all without seeing anything. ## Quick Start Serve my HTML file over HTTP and use Playwright to verify it renders by checking page errors, reading the debug state, and sampling canvas pixels.
